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Sample records for bipolar mitotic spindle

  1. Mitotic spindle proteomics in Chinese hamster ovary cells.

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    Mary Kate Bonner

    Full Text Available Mitosis is a fundamental process in the development of all organisms. The mitotic spindle guides the cell through mitosis as it mediates the segregation of chromosomes, the orientation of the cleavage furrow, and the progression of cell division. Birth defects and tissue-specific cancers often result from abnormalities in mitotic events. Here, we report a proteomic study of the mitotic spindle from Chinese Hamster Ovary (CHO cells. Four different isolations of metaphase spindles were subjected to Multi-dimensional Protein Identification Technology (MudPIT analysis and tandem mass spectrometry. We identified 1155 proteins and used Gene Ontology (GO analysis to categorize proteins into cellular component groups. We then compared our data to the previously published CHO midbody proteome and identified proteins that are unique to the CHO spindle. Our data represent the first mitotic spindle proteome in CHO cells, which augments the list of mitotic spindle components from mammalian cells.

  2. Smurf2 as a novel mitotic regulator: From the spindle assembly checkpoint to tumorigenesis

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    Moore Finola E

    2009-07-01

    Full Text Available Abstract The execution of the mitotic program with high fidelity is dependent upon precise spatiotemporal regulation of posttranslational protein modifications. For example, the timely polyubiquitination of critical mitotic regulators by Anaphase Promoting Complex/Cyclosome (APC/C is essential for the metaphase to anaphase transition and mitotic exit. The spindle assembly checkpoint prevents unscheduled activity of APC/C-Cdc20 in early mitosis, allowing bipolar attachment of kinetochores to mitotic spindle and facilitating equal segregation of sister chromatids. The critical effector of the spindle checkpoint, Mitotic arrest deficient 2 (Mad2, is recruited to unattached kinetochores forming a complex with other regulatory proteins to efficiently and cooperatively inhibit APC/C-Cdc20. A weakened and/or dysfunctional spindle checkpoint has been linked to the development of genomic instability in both cell culture and animal models, and evidence suggests that aberrant regulation of the spindle checkpoint plays a critical role in human carcinogenesis. Recent studies have illuminated a network of both degradative and non-degradative ubiquitination events that regulate the metaphase to anaphase transition and mitotic exit. Within this context, our recent work showed that the HECT (Homologous to E6-AP C-terminus-family E3 ligase Smurf2 (Smad specific ubiquitin regulatory factor 2, known as a negative regulator of transforming growth factor-beta (TGF-β signaling, is required for a functional spindle checkpoint by promoting the functional localization and stability of Mad2. Here we discuss putative models explaining the role of Smurf2 as a new regulator in the spindle checkpoint. The dynamic mitotic localization of Smurf2 to the centrosome and other critical mitotic structures provides implications about mitotic checkpoint control dependent on various ubiquitination events. Finally, deregulated Smurf2 activity may contribute to carcinogenesis by

  3. Axin localizes to mitotic spindles and centrosomes in mitotic cells

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    Kim, Shi-Mun; Choi, Eun-Jin; Song, Ki-Joon; Kim, Sewoon; Seo, Eunjeong; Jho, Eek-Hoon; Kee, Sun-Ho

    2009-01-01

    Wnt signaling plays critical roles in cell proliferation and carcinogenesis. In addition, numerous recent studies have shown that various Wnt signaling components are involved in mitosis and chromosomal instability. However, the role of Axin, a negative regulator of Wnt signaling, in mitosis has remained unclear. Using monoclonal antibodies against Axin, we found that Axin localizes to the centrosome and along mitotic spindles. This localization was suppressed by siRNA specific for Aurora A kinase and by Aurora kinase inhibitor. Interestingly, Axin over-expression altered the subcellular distribution of Plk1 and of phosphorylated glycogen synthase kinase (GSK3β) without producing any notable changes in cellular phenotype. In the presence of Aurora kinase inhibitor, Axin over-expression induced the formation of cleavage furrow-like structures and of prominent astral microtubules lacking midbody formation in a subset of cells. Our results suggest that Axin modulates distribution of Axin-associated proteins such as Plk1 and GSK3β in an expression level-dependent manner and these interactions affect the mitotic process, including cytokinesis under certain conditions, such as in the presence of Aurora kinase inhibitor

  4. Interaction between Poly(ADP-ribose) and NuMA contributes to mitotic spindle pole assembly.

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    Chang, Paul; Coughlin, Margaret; Mitchison, Timothy J

    2009-11-01

    Poly(ADP-ribose) (pADPr), made by PARP-5a/tankyrase-1, localizes to the poles of mitotic spindles and is required for bipolar spindle assembly, but its molecular function in the spindle is poorly understood. To investigate this, we localized pADPr at spindle poles by immuno-EM. We then developed a concentrated mitotic lysate system from HeLa cells to probe spindle pole assembly in vitro. Microtubule asters assembled in response to centrosomes and Ran-GTP in this system. Magnetic beads coated with pADPr, extended from PARP-5a, also triggered aster assembly, suggesting a functional role of the pADPr in spindle pole assembly. We found that PARP-5a is much more active in mitosis than interphase. We used mitotic PARP-5a, self-modified with pADPr chains, to capture mitosis-specific pADPr-binding proteins. Candidate binding proteins included the spindle pole protein NuMA previously shown to bind to PARP-5a directly. The rod domain of NuMA, expressed in bacteria, bound directly to pADPr. We propose that pADPr provides a dynamic cross-linking function at spindle poles by extending from covalent modification sites on PARP-5a and NuMA and binding noncovalently to NuMA and that this function helps promote assembly of exactly two poles.

  5. Reconstitution of basic mitotic spindles in spherical emulsion droplets

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    Vleugel, M.; Roth, S.C.A.; Groenendijk, Celebrity F.; Dogterom, A.M.

    2016-01-01

    Mitotic spindle assembly, positioning and orientation depend on the combined forces generated by microtubule dynamics, microtubule motor proteins and cross-linkers. Growing microtubules can generate pushing forces, while depolymerizing microtubules can convert the energy from microtubule

  6. In-silico modeling of the mitotic spindle assembly checkpoint.

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    Bashar Ibrahim

    2008-02-01

    Full Text Available The Mitotic Spindle Assembly Checkpoint ((MSAC is an evolutionary conserved mechanism that ensures the correct segregation of chromosomes by restraining cell cycle progression from entering anaphase until all chromosomes have made proper bipolar attachments to the mitotic spindle. Its malfunction can lead to cancer.We have constructed and validated for the human (MSAC mechanism an in silico dynamical model, integrating 11 proteins and complexes. The model incorporates the perspectives of three central control pathways, namely Mad1/Mad2 induced Cdc20 sequestering based on the Template Model, MCC formation, and APC inhibition. Originating from the biochemical reactions for the underlying molecular processes, non-linear ordinary differential equations for the concentrations of 11 proteins and complexes of the (MSAC are derived. Most of the kinetic constants are taken from literature, the remaining four unknown parameters are derived by an evolutionary optimization procedure for an objective function describing the dynamics of the APC:Cdc20 complex. MCC:APC dissociation is described by two alternatives, namely the "Dissociation" and the "Convey" model variants. The attachment of the kinetochore to microtubuli is simulated by a switching parameter silencing those reactions which are stopped by the attachment. For both, the Dissociation and the Convey variants, we compare two different scenarios concerning the microtubule attachment dependent control of the dissociation reaction. Our model is validated by simulation of ten perturbation experiments.Only in the controlled case, our models show (MSAC behaviour at meta- to anaphase transition in agreement with experimental observations. Our simulations revealed that for (MSAC activation, Cdc20 is not fully sequestered; instead APC is inhibited by MCC binding.

  7. Regulation of mitotic progression by the spindle assembly checkpoint

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    Lischetti, Tiziana; Nilsson, Jakob

    2015-01-01

    Equal segregation of sister chromatids during mitosis requires that pairs of kinetochores establish proper attachment to microtubules emanating from opposite poles of the mitotic spindle. The spindle assembly checkpoint (SAC) protects against errors in segregation by delaying sister separation...... in response to improper kinetochore-microtubule interactions, and certain checkpoint proteins help to establish proper attachments. Anaphase entry is inhibited by the checkpoint through assembly of the mitotic checkpoint complex (MCC) composed of the 2 checkpoint proteins, Mad2 and BubR1, bound to Cdc20...

  8. Nuclear Mitotic Apparatus (NuMA) Interacts with and Regulates Astrin at the Mitotic Spindle.

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    Chu, Xiaogang; Chen, Xuanyu; Wan, Qingwen; Zheng, Zhen; Du, Quansheng

    2016-09-16

    The large nuclear mitotic apparatus (NuMA) protein is an essential player in mitotic spindle assembly and maintenance. We report here the identification of Astrin, a spindle- and kinetochore-associated protein, as a novel interactor of NuMA. We show that the C-terminal tail of NuMA can directly bind to the C terminus of Astrin and that this interaction helps to recruit Astrin to microtubules. Knockdown of NuMA by RNA interference dramatically impaired Astrin recruitment to the mitotic spindle. Overexpression of the N terminus of mammalian homologue of Drosophila Pins (LGN), which blocks the microtubule binding of NuMA and competes with Astrin for NuMA binding, also led to similar results. Furthermore, we found that cytoplasmic dynein is required for the spindle pole accumulation of Astrin, and dynein-mediated transport is important for balanced distribution of Astrin between spindle poles and kinetochores. On the other hand, if Astrin levels are reduced, then NuMA could not efficiently concentrate at the spindle poles. Our findings reveal a direct physical link between two important regulators of mitotic progression and demonstrate the critical role of the NuMA-Astrin interaction for accurate cell division. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Pattern formation in stochastic systems: Magnetized billiards and mitotic spindles

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    Schaffner, Stuart C.

    Physical systems that exhibit chaotic behavior or are subject to thermal noise are treated as random processes, especially if the state of the system cannot be measured precisely. Here we examine two such systems. The first is a single electron confined to a wedge-shaped section of a disk, called a billiard, in the presence of a uniform transverse magnetic field. The system exhibits a mixture of chaotic and nonchaotic behavior at different values of the magnetic field strength. If the size of the billiard is on the order of micrometers, as in a quantum dot, both quantum and classical analyses are necessary. The second system is a collection of stiff fibers, called microtubules, suspended in a fluid called the cytoplasm, and lying over chromosomes in a cell. The cytoplasm supplies molecular motors and fuel for the motors. The chromosomes supply motor attachment points. The combination causes the microtubules to self-assemble into a coherent structure called the mitotic spindle. This structure is vital to cell division in plants and animals. Elements of the mitotic spindle have sizes ranging from nanometers to micrometers, and all are subject to considerable thermal agitation. Mitotic spindle self-assembly occurs despite the randomizing effect of this thermal motion. We studied both systems by constructing physical models described by mathematical equations. From these we were able to perform computer simulations. For the billiard problem, we made innovative use of geometric symmetries. These symmetries allowed us to construct efficient representations of both classical and quantum systems. We found a new region of integrable trajectories for a magnetic field above that required to produce completely chaotic orbits. For the mitotic spindle, we were the first to demonstrate spindle self-assembly in a model that matches conditions reported by experimental biologists. Our simulations have shed significant light on which of the many elements in this complex system are

  10. Physical Limits on the Precision of Mitotic Spindle Positioning by Microtubule Pushing forces: Mechanics of mitotic spindle positioning.

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    Howard, Jonathon; Garzon-Coral, Carlos

    2017-11-01

    Tissues are shaped and patterned by mechanical and chemical processes. A key mechanical process is the positioning of the mitotic spindle, which determines the size and location of the daughter cells within the tissue. Recent force and position-fluctuation measurements indicate that pushing forces, mediated by the polymerization of astral microtubules against- the cell cortex, maintain the mitotic spindle at the cell center in Caenorhabditis elegans embryos. The magnitude of the centering forces suggests that the physical limit on the accuracy and precision of this centering mechanism is determined by the number of pushing microtubules rather than by thermally driven fluctuations. In cells that divide asymmetrically, anti-centering, pulling forces generated by cortically located dyneins, in conjunction with microtubule depolymerization, oppose the pushing forces to drive spindle displacements away from the center. Thus, a balance of centering pushing forces and anti-centering pulling forces localize the mitotic spindles within dividing C. elegans cells. © 2017 The Authors. BioEssays published by Wiley Periodicals, Inc.

  11. CENP-W plays a role in maintaining bipolar spindle structure.

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    Agnieszka Kaczmarczyk

    Full Text Available The CENP-W/T complex was previously reported to be required for mitosis. HeLa cells depleted of CENP-W displayed profound mitotic defects, with mitotic timing delay, disorganized prometaphases and multipolar spindles as major phenotypic consequences. In this study, we examined the process of multipolar spindle formation induced by CENP-W depletion. Depletion of CENP-W in HeLa cells labeled with histone H2B and tubulin fluorescent proteins induced rapid fragmentation of originally bipolar spindles in a high proportion of cells. CENP-W depletion was associated with depletion of Hec1 at kinetochores. The possibility of promiscuous centrosomal duplication was ruled out by immunofluorescent examination of centrioles. However, centrioles were frequently observed to be abnormally split. In addition, a large proportion of the supernumerary poles lacked centrioles, but were positively stained with different centrosomal markers. These observations suggested that perturbation in spindle force distribution caused by defective kinetochores could contribute to a mechanical mechanism for spindle pole disruption. 'Spindle free' nocodazole arrested cells did not exhibit pole fragmentation after CENP-W depletion, showing that pole fragmentation is microtubule dependent. Inhibition of centrosome separation by monastrol reduced the incidence of spindle pole fragmentation, indicating that Eg5 plays a role in spindle pole disruption. Surprisingly, CENP-W depletion rescued the monopolar spindle phenotype of monastrol treatment, with an increased frequency of bipolar spindles observed after CENP-W RNAi. We overexpressed the microtubule cross-linking protein TPX2 to create spindle poles stabilized by the microtubule cross-linking activity of TPX2. Spindle pole fragmentation was suppressed in a TPX2-dependent fashion. We propose that CENP-W, by influencing proper kinetochore assembly, particularly microtubule docking sites, can confer spindle pole resistance to traction

  12. Nup98 regulates bipolar spindle assembly through association with microtubules and opposition of MCAK.

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    Cross, Marie K; Powers, Maureen A

    2011-03-01

    During mitosis, the nuclear pore complex is disassembled and, increasingly, nucleoporins are proving to have mitotic functions when released from the pore. We find a contribution of the nucleoporin Nup98 to mitotic spindle assembly through regulation of microtubule dynamics. When added to Xenopus extract spindle assembly assays, the C-terminal domain of Nup98 stimulates uncontrolled growth of microtubules. Conversely, inhibition or depletion of Nup98 leads to formation of stable monopolar spindles. Spindle bipolarity is restored by addition of purified, recombinant Nup98 C-terminus. The minimal required region of Nup98 corresponds to a portion of the C-terminal domain lacking a previously characterized function. We show association between this region of the C-terminus of Nup98 and both Taxol-stabilized microtubules and the microtubule-depolymerizing mitotic centromere-associated kinesin (MCAK). Importantly, we demonstrate that this domain of Nup98 inhibits MCAK depolymerization activity in vitro. These data support a model in which Nup98 interacts with microtubules and antagonizes MCAK activity, thus promoting bipolar spindle assembly.

  13. Multisite Phosphorylation of NuMA-Related LIN-5 Controls Mitotic Spindle Positioning in C. elegans

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    Portegijs, Vincent; Fielmich, Lars-Eric; Galli, Matilde; Schmidt, Ruben; Munoz Peralta, Javier; van Mourik, Tim; Akhmanova, Anna; Heck, Albert J R; Boxem, Mike; van den Heuvel, Sander

    2016-01-01

    During cell division, the mitotic spindle segregates replicated chromosomes to opposite poles of the cell, while the position of the spindle determines the plane of cleavage. Spindle positioning and chromosome segregation depend on pulling forces on microtubules extending from the centrosomes to the

  14. A LCMT1-PME-1 methylation equilibrium controls mitotic spindle size.

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    Xia, Xiaoyu; Gholkar, Ankur; Senese, Silvia; Torres, Jorge Z

    2015-01-01

    Leucine carboxyl methyltransferase-1 (LCMT1) and protein phosphatase methylesterase-1 (PME-1) are essential enzymes that regulate the methylation of the protein phosphatase 2A catalytic subunit (PP2AC). LCMT1 and PME-1 have been linked to the regulation of cell growth and proliferation, but the underlying mechanisms have remained elusive. We show here an important role for an LCMT1-PME-1 methylation equilibrium in controlling mitotic spindle size. Depletion of LCMT1 or overexpression of PME-1 led to long spindles. In contrast, depletion of PME-1, pharmacological inhibition of PME-1 or overexpression of LCMT1 led to short spindles. Furthermore, perturbation of the LCMT1-PME-1 methylation equilibrium led to mitotic arrest, spindle assembly checkpoint activation, defective cell divisions, induction of apoptosis and reduced cell viability. Thus, we propose that the LCMT1-PME-1 methylation equilibrium is critical for regulating mitotic spindle size and thereby proper cell division.

  15. Rae1 interaction with NuMA is required for bipolar spindle formation.

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    Wong, Richard W; Blobel, Günter; Coutavas, Elias

    2006-12-26

    In eukaryotic cells, the faithful segregation of daughter chromosomes during cell division depends on formation of a microtubule (MT)-based bipolar spindle apparatus. The Nuclear Mitotic Apparatus protein (NuMA) is recruited from interphase nuclei to spindle MTs during mitosis. The carboxy terminal domain of NuMA binds MTs, allowing a NuMA dimer to function as a "divalent" crosslinker that bundles MTs. The messenger RNA export factor, Rae1, also binds to MTs. Lowering Rae1 or increasing NuMA levels in cells results in spindle abnormalities. We have identified a mitotic-specific interaction between Rae1 and NuMA and have explored the relationship between Rae1 and NuMA in spindle formation. We have mapped a specific binding site for Rae1 on NuMA that would convert a NuMA dimer to a "tetravalent" crosslinker of MTs. In mitosis, reducing Rae1 or increasing NuMA concentration would be expected to alter the valency of NuMA toward MTs; the "density" of NuMA-MT crosslinks in these conditions would be diminished, even though a threshold number of crosslinks sufficient to stabilize aberrant multipolar spindles may form. Consistent with this interpretation, we found that coupling NuMA overexpression to Rae1 overexpression or coupling Rae1 depletion to NuMA depletion prevented the formation of aberrant spindles. Likewise, we found that overexpression of the specific Rae1-binding domain of NuMA in HeLa cells led to aberrant spindle formation. These data point to the Rae1-NuMA interaction as a critical element for normal spindle formation in mitosis.

  16. A mammalian Partner of inscuteable binds NuMA and regulates mitotic spindle organization.

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    Du, Q; Stukenberg, P T; Macara, I G

    2001-12-01

    Asymmetric cell division requires the orientation of mitotic spindles along the cell-polarity axis. In Drosophila neuroblasts, this involves the interaction of the proteins Inscuteable (Insc) and Partner of inscuteable (Pins). We report here that a human Pins-related protein, called LGN, is instead essential for the assembly and organization of the mitotic spindle. LGN is cytoplasmic in interphase cells, but associates with the spindle poles during mitosis. Ectopic expression of LGN disrupts spindle-pole organization and chromosome segregation. Silencing of LGN expression by RNA interference also disrupts spindle-pole organization and prevents normal chromosome segregation. We found that LGN binds the nuclear mitotic apparatus protein NuMA, which tethers spindles at the poles, and that this interaction is required for the LGN phenotype. Anti-LGN antibodies and the LGN-binding domain of NuMA both trigger microtubule aster formation in mitotic Xenopus egg extracts, and the NuMA-binding domain of LGN blocks aster assembly in egg extracts treated with taxol. Thus, we have identified a mammalian Pins homologue as a key regulator of spindle organization during mitosis.

  17. The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

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    Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

    2013-01-01

    Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs. PMID:23593258

  18. The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

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    Zhang, Gang; Beati, Hamze; Nilsson, Jakob; Wodarz, Andreas

    2013-01-01

    Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

  19. The Drosophila microtubule-associated protein mars stabilizes mitotic spindles by crosslinking microtubules through its N-terminal region.

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    Gang Zhang

    Full Text Available Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs have been reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function. Here we show that Mars is able to stabilize the mitotic spindle in vivo. Both in vivo and in vitro data reveal that the N-terminal region of Mars functions in the stabilization of the mitotic spindle by crosslinking adjacent MTs.

  20. The Drosophila Microtubule-Associated Protein Mars Stabilizes Mitotic Spindles by Crosslinking Microtubules through Its N-Terminal Region

    DEFF Research Database (Denmark)

    Zhang, Gang; Beati, Hamze; Nilsson, Jakob

    2013-01-01

    Correct segregation of genetic material relies on proper assembly and maintenance of the mitotic spindle. How the highly dynamic microtubules (MTs) are maintained in stable mitotic spindles is a key question to be answered. Motor and non-motor microtubule associated proteins (MAPs) have been...... reported to stabilize the dynamic spindle through crosslinking adjacent MTs. Mars, a novel MAP, is essential for the early development of Drosophila embryos. Previous studies showed that Mars is required for maintaining an intact mitotic spindle but did not provide a molecular mechanism for this function...

  1. Exclusive destruction of mitotic spindles in human cancer cells.

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    Visochek, Leonid; Castiel, Asher; Mittelman, Leonid; Elkin, Michael; Atias, Dikla; Golan, Talia; Izraeli, Shai; Peretz, Tamar; Cohen-Armon, Malka

    2017-03-28

    We identified target proteins modified by phenanthrenes that cause exclusive eradication of human cancer cells. The cytotoxic activity of the phenanthrenes in a variety of human cancer cells is attributed by these findings to post translational modifications of NuMA and kinesins HSET/kifC1 and kif18A. Their activity prevented the binding of NuMA to α-tubulin and kinesins in human cancer cells, and caused aberrant spindles. The most efficient cytotoxic activity of the phenanthridine PJ34, caused significantly smaller aberrant spindles with disrupted spindle poles and scattered extra-centrosomes and chromosomes. Concomitantly, PJ34 induced tumor growth arrest of human malignant tumors developed in athymic nude mice, indicating the relevance of its activity for cancer therapy.

  2. Downregulation of Protein 4.1R impairs centrosome function,bipolar spindle organization and anaphase

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    Spence, Jeffrey R.; Go, Minjoung M.; Bahmanyar, S.; Barth,A.I.M.; Krauss, Sharon Wald

    2006-03-17

    Centrosomes nucleate and organize interphase MTs and areinstrumental in the assembly of the mitotic bipolar spindle. Here wereport that two members of the multifunctional protein 4.1 family havedistinct distributions at centrosomes. Protein 4.1R localizes to maturecentrioles whereas 4.1G is a component of the pericentriolar matrixsurrounding centrioles. To selectively probe 4.1R function, we used RNAinterference-mediated depletion of 4.1R without decreasing 4.1Gexpression. 4.1R downregulation reduces MT anchoring and organization atinterphase and impairs centrosome separation during prometaphase.Metaphase chromosomes fail to properly condense/align and spindleorganization is aberrant. Notably 4.1R depletion causes mislocalizationof its binding partner NuMA (Nuclear Mitotic Apparatus Protein),essential for spindle pole focusing, and disrupts ninein. Duringanaphase/telophase, 4.1R-depleted cells have lagging chromosomes andaberrant MT bridges. Our data provide functional evidence that 4.1R makescrucial contributions to centrosome integrity and to mitotic spindlestructure enabling mitosis and anaphase to proceed with the coordinatedprecision required to avoid pathological events.

  3. Automated high-throughput quantification of mitotic spindle positioning from DIC movies of Caenorhabditis embryos.

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    David Cluet

    Full Text Available The mitotic spindle is a microtubule-based structure that elongates to accurately segregate chromosomes during anaphase. Its position within the cell also dictates the future cell cleavage plan, thereby determining daughter cell orientation within a tissue or cell fate adoption for polarized cells. Therefore, the mitotic spindle ensures at the same time proper cell division and developmental precision. Consequently, spindle dynamics is the matter of intensive research. Among the different cellular models that have been explored, the one-cell stage C. elegans embryo has been an essential and powerful system to dissect the molecular and biophysical basis of spindle elongation and positioning. Indeed, in this large and transparent cell, spindle poles (or centrosomes can be easily detected from simple DIC microscopy by human eyes. To perform quantitative and high-throughput analysis of spindle motion, we developed a computer program ACT for Automated-Centrosome-Tracking from DIC movies of C. elegans embryos. We therefore offer an alternative to the image acquisition and processing of transgenic lines expressing fluorescent spindle markers. Consequently, experiments on large sets of cells can be performed with a simple setup using inexpensive microscopes. Moreover, analysis of any mutant or wild-type backgrounds is accessible because laborious rounds of crosses with transgenic lines become unnecessary. Last, our program allows spindle detection in other nematode species, offering the same quality of DIC images but for which techniques of transgenesis are not accessible. Thus, our program also opens the way towards a quantitative evolutionary approach of spindle dynamics. Overall, our computer program is a unique macro for the image- and movie-processing platform ImageJ. It is user-friendly and freely available under an open-source licence. ACT allows batch-wise analysis of large sets of mitosis events. Within 2 minutes, a single movie is processed

  4. Computational analysis of the spatial distribution of mitotic spindle angles in mouse developing airway

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    Tang, Nan; Marshall, Wallace F.

    2013-02-01

    Investigating the spatial information of cellular processes in tissues during mouse embryo development is one of the major technical challenges in development biology. Many imaging methods are still limited to the volumes of tissue due to tissue opacity, light scattering and the availability of advanced imaging tools. For analyzing the mitotic spindle angle distribution in developing mouse airway epithelium, we determined spindle angles in mitotic epithelial cells on serial sections of whole airway of mouse embryonic lungs. We then developed a computational image analysis to obtain spindle angle distribution in three dimensional airway reconstructed from the data obtained from all serial sections. From this study, we were able to understand how mitotic spindle angles are distributed in a whole airway tube. This analysis provides a potentially fast, simple and inexpensive alternative method to quantitatively analyze cellular process at subcellular resolution. Furthermore, this analysis is not limited to the size of tissues, which allows to obtain three dimensional and high resolution information of cellular processes in cell populations deeper inside intact organs.

  5. The role of p53 in the response to mitotic spindle damage

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    Meek, D.W.

    2000-01-01

    The p53 tumour suppressor protein has defined roles in G1/S and G2/M cell cycle checkpoint in response to a range of cellular stresses including DNA damage, dominant oncogene expression, hypoxia, metabolic changes and viral infection. In addition to these responses, p53 can also be activated when damage occurs to the mitotic spindle. Initially, spindle damage activates a p53-independent checkpoint which functions at the metaphase-anaphase transition and prevents cells from progressing through mitosis until the completion of spindle formation. Cells eventually escape from this block (a process termed 'mitotic slippage'), and an aberrant mitosis ensues in which sister chromatids fail to segregate properly. After a delay period, p53 responds to this mitotic failure by instituting a G1-like growth arrest, with an intact nucleus containing 4N DNA, but without the cells undergoing division. Cells lacking wild-type p53 are still able to arrest transiently at mitosis, and also fail to undergo division, underscoring that the delay in mitosis is p53-independent. However, these cells are not prevented from re-entering the cell cycle and can reduplicate their DNA unchecked, leading to polyploidy. Additionally, p53-null cells which experience spindle failure often show the appearance of micronuclei arising from poorly segregated chromosomes which have de-condensed and been enclosed in a nuclear envelope. The ability of p53 to prevent their formation suggests an additional G2 involvement which prevents nuclear breakdown prior to mitosis. The molecular mechanism by which p53 is able to sense mitotic failure is still unknown, but may be linked to the ability of p53 to regulate duplication of the centrosome, the organelle which nucleates spindle formation. (authors)

  6. A gene encoding the major beta tubulin of the mitotic spindle in Physarum polycephalum plasmodia

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    Burland, T.G.; Paul, E.C.A.; Oetliker, M.; Dove, W.F.

    1988-03-01

    The multinucleate plasmodium of Physarum polycephalum is unusual among eucaryotic cells in that it uses tubulins only in mitotic-spindle microtubules; cytoskeletal, flagellar, and centriolar microtubules are absent in this cell type. The authors identified a ..beta..-tubulin cDNA clone, ..beta..105, which is shown to correspond to the transcript of the betC ..beta..-tubulin locus and to encode ..beta..2 tubulin, the ..beta.. tubulin expressed specifically in the plasmodium and used exclusively in the mitotic spindle. Physarum amoebae utilize tubulins in the cytoskeleton, centrioles, and flagella, in addition to the mitotic spindle. Sequence analysis shows that ..beta..2 tubulin is only 83% identical to the two ..beta.. tubulins expressed in amoebae. This compares with 70 to 83% identity between Physarum ..beta..2 tubulin and the ..beta.. tubulins of yeasts, fungi, alga, trypanosome, fruit fly, chicken, and mouse. On the other hand, Physarum ..beta..2 tubulin is no more similar to, for example, Aspergillus ..beta.. tubulins than it is to those of Drosophila melanogaster or mammals. Several eucaryotes express at least one widely diverged ..beta.. tubulin as well as one or more ..beta.. tubulins that conform more closely to a consensus ..beta..-tubulin sequence. The authors suggest that ..beta..-tubulins diverge more when their expression pattern is restricted, especially when this restriction results in their use in fewer functions. This divergence among ..beta.. tubulins could have resulted through neutral drift. For example, exclusive use of Physarum ..beta..2 tubulin in the spindle may have allowed more amino acid substitutions than would be functionally tolerable in the ..beta.. tubulins that are utilized in multiple microtubular organelles. Alternatively, restricted use of ..beta.. tubulins may allow positive selection to operate more freely to refine ..beta..-tubulin function.

  7. Multisite Phosphorylation of NuMA-Related LIN-5 Controls Mitotic Spindle Positioning in C. elegans.

    Science.gov (United States)

    Portegijs, Vincent; Fielmich, Lars-Eric; Galli, Matilde; Schmidt, Ruben; Muñoz, Javier; van Mourik, Tim; Akhmanova, Anna; Heck, Albert J R; Boxem, Mike; van den Heuvel, Sander

    2016-10-01

    During cell division, the mitotic spindle segregates replicated chromosomes to opposite poles of the cell, while the position of the spindle determines the plane of cleavage. Spindle positioning and chromosome segregation depend on pulling forces on microtubules extending from the centrosomes to the cell cortex. Critical in pulling force generation is the cortical anchoring of cytoplasmic dynein by a conserved ternary complex of Gα, GPR-1/2, and LIN-5 proteins in C. elegans (Gα-LGN-NuMA in mammals). Previously, we showed that the polarity kinase PKC-3 phosphorylates LIN-5 to control spindle positioning in early C. elegans embryos. Here, we investigate whether additional LIN-5 phosphorylations regulate cortical pulling forces, making use of targeted alteration of in vivo phosphorylated residues by CRISPR/Cas9-mediated genetic engineering. Four distinct in vivo phosphorylated LIN-5 residues were found to have critical functions in spindle positioning. Two of these residues form part of a 30 amino acid binding site for GPR-1, which we identified by reverse two-hybrid screening. We provide evidence for a dual-kinase mechanism, involving GSK3 phosphorylation of S659 followed by phosphorylation of S662 by casein kinase 1. These LIN-5 phosphorylations promote LIN-5-GPR-1/2 interaction and contribute to cortical pulling forces. The other two critical residues, T168 and T181, form part of a cyclin-dependent kinase consensus site and are phosphorylated by CDK1-cyclin B in vitro. We applied a novel strategy to characterize early embryonic defects in lethal T168,T181 knockin substitution mutants, and provide evidence for sequential LIN-5 N-terminal phosphorylation and dephosphorylation in dynein recruitment. Our data support that phosphorylation of multiple LIN-5 domains by different kinases contributes to a mechanism for spatiotemporal control of spindle positioning and chromosome segregation.

  8. Semaphorin-Plexin Signaling Controls Mitotic Spindle Orientation during Epithelial Morphogenesis and Repair

    DEFF Research Database (Denmark)

    Xia, Jingjing; Swiercz, Jakub M.; Bañón-Rodríguez, Inmaculada

    2015-01-01

    show that this alignment depends on epithelial cell-cell communication via semaphorin-plexin signaling. During kidney morphogenesis and repair, renal tubular epithelial cells lacking the transmembrane receptor Plexin-B2 or its semaphorin ligands fail to correctly orient the mitotic spindle, leading...... to severe defects in epithelial architecture and function. Analyses of a series of transgenic and knockout mice indicate that Plexin-B2 controls the cell division axis by signaling through its GTPase-activating protein (GAP) domain and Cdc42. Our data uncover semaphorin-plexin signaling as a central...

  9. The GTPase Gem and its partner Kif9 are required for chromosome alignment, spindle length control, and mitotic progression.

    Science.gov (United States)

    Andrieu, Guillaume; Quaranta, Muriel; Leprince, Corinne; Hatzoglou, Anastassia

    2012-12-01

    Within the Ras superfamily, Gem is a small GTP-binding protein that plays a role in regulating Ca(2+) channels and cytoskeletal remodeling in interphase cells. Here, we report for the first time that Gem is a spindle-associated protein and is required for proper mitotic progression. Functionally, loss of Gem leads to misaligned chromosomes and prometaphase delay. On the basis of different experimental approaches, we demonstrate that loss of Gem by RNA interference induces spindle elongation, while its enforced expression results in spindle shortening. The spindle length phenotype is generated through deregulation of spindle dynamics on Gem depletion and requires the expression of its downstream effector, the kinesin Kif9. Loss of Kif9 induces spindle abnormalities similar to those observed when Gem expression is repressed by siRNA. We further identify Kif9 as a new regulator of spindle dynamics. Kif9 depletion increases the steady-state levels of spindle α-tubulin by increasing the rate of microtubule polymerization. Overall, this study demonstrates a novel mechanism by which Gem contributes to the mitotic progression by maintaining correct spindle length through the kinesin Kif9.

  10. Interaction of NuMA protein with the kinesin Eg5: its possible role in bipolar spindle assembly and chromosome alignment.

    Science.gov (United States)

    Iwakiri, Yuko; Kamakura, Sachiko; Hayase, Junya; Sumimoto, Hideki

    2013-04-15

    Bipolar spindle assembly in mitotic cells is a prerequisite to ensure correct alignment of chromosomes for their segregation to each daughter cell; spindle microtubules are tethered at plus ends to chromosomes and focused at minus ends to either of the two spindle poles. NuMA (nuclear mitotic apparatus protein) is present solely in the nucleus in interphase cells, but relocalizes during mitosis to the spindle poles to play a crucial role in spindle assembly via focusing spindle microtubules to each pole. In the present study we show that the kinesin-5 family motor Eg5 is a protein that directly interacts with NuMA, using a proteomics approach and various binding assays both in vivo and in vitro. During mitosis Eg5 appears to interact with NuMA in the vicinity of the spindle poles, whereas the interaction does not occur in interphase cells, where Eg5 is distributed throughout the cytoplasm but NuMA exclusively localizes to the nucleus. Slight, but significant, depletion of Eg5 in HeLa cells by RNA interference results in formation of less-focused spindle poles with misaligned chromosomes in metaphase; these phenotypes are similar to those induced by depletion of NuMA. Since NuMA is less accumulated at the spindle poles in Eg5-depleted cells, Eg5 probably contributes to spindle assembly via regulating NuMA localization. Furthermore, depletion of cytoplasmic dynein induces mislocalization of NuMA and phenotypes similar to those observed in NuMA-depleted cells, without affecting Eg5 localization to the spindles. Thus dynein appears to control NuMA function in conjunction with Eg5.

  11. Regulation of mitotic spindle assembly factor NuMA by Importin-β.

    Science.gov (United States)

    Chang, Chih-Chia; Huang, Tzu-Lun; Shimamoto, Yuta; Tsai, Su-Yi; Hsia, Kuo-Chiang

    2017-11-06

    Ran-guanosine triphosphatase orchestrates mitotic spindle assembly by modulation of the interaction between Importin-α/-β and spindle assembly factors (SAFs). The inhibition of SAFs performed by importins needs to be done without much sequestration from abundant nuclear localization signal (NLS) -containing proteins. However, the molecular mechanisms that determine NLS-binding selectivity and that inhibit activity of Importin-β-regulated SAFs (e.g., nuclear mitotic apparatus protein [NuMA]) remain undefined. Here, we present a crystal structure of the Importin-α-NuMA C terminus complex showing a novel binding pattern that accounts for selective NLS recognition. We demonstrate that, in the presence of Importin-α, Importin-β inhibits the microtubule-binding function of NuMA. Further, we have identified a high-affinity microtubule-binding region that lies carboxyl-terminal to the NLS, which is sterically masked by Importin-β on being bound by Importin-α. Our study provides mechanistic evidence of how Importin-α/-β regulates the NuMA functioning required for assembly of higher-order microtubule structures, further illuminating how Ran-governed transport factors regulate diverse SAFs and accommodate various cell demands. © 2017 Chang et al.

  12. NuMA interacts with phosphoinositides and links the mitotic spindle with the plasma membrane.

    Science.gov (United States)

    Kotak, Sachin; Busso, Coralie; Gönczy, Pierre

    2014-08-18

    The positioning and the elongation of the mitotic spindle must be carefully regulated. In human cells, the evolutionary conserved proteins LGN/Gαi1-3 anchor the coiled-coil protein NuMA and dynein to the cell cortex during metaphase, thus ensuring proper spindle positioning. The mechanisms governing cortical localization of NuMA and dynein during anaphase remain more elusive. Here, we report that LGN/Gαi1-3 are dispensable for NuMA-dependent cortical dynein enrichment during anaphase. We further establish that NuMA is excluded from the equatorial region of the cell cortex in a manner that depends on the centralspindlin components CYK4 and MKLP1. Importantly, we reveal that NuMA can directly associate with PtdInsP (PIP) and PtdInsP2 (PIP2) phosphoinositides in vitro. Furthermore, chemical or enzymatic depletion of PIP/PIP2 prevents NuMA cortical localization during mitosis, and conversely, increasing PIP2 levels augments mitotic cortical NuMA. Overall, our study uncovers a novel function for plasma membrane phospholipids in governing cortical NuMA distribution and thus the proper execution of mitosis. © 2014 The Authors.

  13. LOX is a novel mitotic spindle-associated protein essential for mitosis.

    Science.gov (United States)

    Boufraqech, Myriem; Wei, Darmood; Weyemi, Urbain; Zhang, Lisa; Quezado, Martha; Kalab, Petr; Kebebew, Electron

    2016-05-17

    LOX regulates cancer progression in a variety of human malignancies. It is overexpressed in aggressive cancers and higher expression of LOX is associated with higher cancer mortality. Here, we report a new function of LOX in mitosis. We show that LOX co-localizes to mitotic spindles from metaphase to telophase, and p-H3(Ser10)-positive cells harbor strong LOX staining. Further, purification of mitotic spindles from synchronized cells show that LOX fails to bind to microtubules in the presence of nocodazole, whereas paclitaxel treated samples showed enrichment in LOX expression, suggesting that LOX binds to stabilized microtubules. LOX knockdown leads to G2/M phase arrest; reduced p-H3(Ser10), cyclin B1, CDK1, and Aurora B. Moreover, LOX knockdown significantly increased sensitivity of cancer cells to chemotherapeutic agents that target microtubules. Our findings suggest that LOX has a role in cancer cell mitosis and may be targeted to enhance the activity of microtubule inhibitors for cancer therapy.

  14. Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

    International Nuclear Information System (INIS)

    Yu, Yueyang; Munger, Karl

    2012-01-01

    The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore–microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

  15. Human papillomavirus type 16 E7 oncoprotein engages but does not abrogate the mitotic spindle assembly checkpoint

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Yueyang [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States); Munger, Karl, E-mail: kmunger@rics.bwh.harvard.edu [Division of Infectious Diseases, Brigham and Women' s Hospital and Biological and Biomedical Sciences Program, Harvard Medical School, Boston, MA 02115 (United States)

    2012-10-10

    The mitotic spindle assembly checkpoint (SAC) ensures faithful chromosome segregation during mitosis by censoring kinetochore-microtubule interactions. It is frequently rendered dysfunctional during carcinogenesis causing chromosome missegregation and genomic instability. There are conflicting reports whether the HPV16 E7 oncoprotein drives chromosomal instability by abolishing the SAC. Here we report that degradation of mitotic cyclins is impaired in cells with HPV16 E7 expression. RNAi-mediated depletion of Mad2 or BubR1 indicated the involvement of the SAC, suggesting that HPV16 E7 expression causes sustained SAC engagement. Mutational analyses revealed that HPV16 E7 sequences that are necessary for retinoblastoma tumor suppressor protein binding as well as sequences previously implicated in binding the nuclear and mitotic apparatus (NuMA) protein and in delocalizing dynein from the mitotic spindle contribute to SAC engagement. Importantly, however, HPV16 E7 does not markedly compromise the SAC response to microtubule poisons.

  16. The SUMO protease SENP1 is required for cohesion maintenance and mitotic arrest following spindle poison treatment

    Energy Technology Data Exchange (ETDEWEB)

    Era, Saho [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Abe, Takuya; Arakawa, Hiroshi [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Kobayashi, Shunsuke [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Szakal, Barnabas [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy); Yoshikawa, Yusuke; Motegi, Akira; Takeda, Shunichi [Radiation Genetics, Graduate School of Medicine, Kyoto University, Yoshida-Konoe, Sakyo-ku, Kyoto 606-8501 (Japan); Branzei, Dana, E-mail: dana.branzei@ifom.eu [Fondazione IFOM, Istituto FIRC di Oncologia Molecolare, IFOM-IEO campus, Via Adamello 16, 20139 Milan (Italy)

    2012-09-28

    Highlights: Black-Right-Pointing-Pointer SENP1 knockout chicken DT40 cells are hypersensitive to spindle poisons. Black-Right-Pointing-Pointer Spindle poison treatment of SENP1{sup -/-} cells leads to increased mitotic slippage. Black-Right-Pointing-Pointer Mitotic slippage in SENP1{sup -/-} cells associates with apoptosis and endoreplication. Black-Right-Pointing-Pointer SENP1 counteracts sister chromatid separation during mitotic arrest. Black-Right-Pointing-Pointer Plk1-mediated cohesion down-regulation is involved in colcemid cytotoxicity. -- Abstract: SUMO conjugation is a reversible posttranslational modification that regulates protein function. SENP1 is one of the six SUMO-specific proteases present in vertebrate cells and its altered expression is observed in several carcinomas. To characterize SENP1 role in genome integrity, we generated Senp1 knockout chicken DT40 cells. SENP1{sup -/-} cells show normal proliferation, but are sensitive to spindle poisons. This hypersensitivity correlates with increased sister chromatid separation, mitotic slippage, and apoptosis. To test whether the cohesion defect had a causal relationship with the observed mitotic events, we restored the cohesive status of sister chromatids by introducing the TOP2{alpha}{sup +/-} mutation, which leads to increased catenation, or by inhibiting Plk1 and Aurora B kinases that promote cohesin release from chromosomes during prolonged mitotic arrest. Although TOP2{alpha} is SUMOylated during mitosis, the TOP2{alpha}{sup +/-} mutation had no obvious effect. By contrast, inhibition of Plk1 or Aurora B rescued the hypersensitivity of SENP1{sup -/-} cells to colcemid. In conclusion, we identify SENP1 as a novel factor required for mitotic arrest and cohesion maintenance during prolonged mitotic arrest induced by spindle poisons.

  17. A lateral belt of cortical LGN and NuMA guides mitotic spindle movements and planar division in neuroepithelial cells.

    Science.gov (United States)

    Peyre, Elise; Jaouen, Florence; Saadaoui, Mehdi; Haren, Laurence; Merdes, Andreas; Durbec, Pascale; Morin, Xavier

    2011-04-04

    To maintain tissue architecture, epithelial cells divide in a planar fashion, perpendicular to their main polarity axis. As the centrosome resumes an apical localization in interphase, planar spindle orientation is reset at each cell cycle. We used three-dimensional live imaging of GFP-labeled centrosomes to investigate the dynamics of spindle orientation in chick neuroepithelial cells. The mitotic spindle displays stereotypic movements during metaphase, with an active phase of planar orientation and a subsequent phase of planar maintenance before anaphase. We describe the localization of the NuMA and LGN proteins in a belt at the lateral cell cortex during spindle orientation. Finally, we show that the complex formed of LGN, NuMA, and of cortically located Gαi subunits is necessary for spindle movements and regulates the dynamics of spindle orientation. The restricted localization of LGN and NuMA in the lateral belt is instructive for the planar alignment of the mitotic spindle, and required for its planar maintenance.

  18. Regulation of mitotic spindle formation by the RhoA guanine nucleotide exchange factor ARHGEF10

    Directory of Open Access Journals (Sweden)

    Satoh Takaya

    2009-07-01

    Full Text Available Abstract Background The Dbl family guanine nucleotide exchange factor ARHGEF10 was originally identified as the product of the gene associated with slowed nerve-conduction velocities of peripheral nerves. However, the function of ARHGEF10 in mammalian cells is totally unknown at a molecular level. ARHGEF10 contains no distinctive functional domains except for tandem Dbl homology-pleckstrin homology and putative transmembrane domains. Results Here we show that RhoA is a substrate for ARHGEF10. In both G1/S and M phases, ARHGEF10 was localized in the centrosome in adenocarcinoma HeLa cells. Furthermore, RNA interference-based knockdown of ARHGEF10 resulted in multipolar spindle formation in M phase. Each spindle pole seems to contain a centrosome consisting of two centrioles and the pericentriolar material. Downregulation of RhoA elicited similar phenotypes, and aberrant mitotic spindle formation following ARHGEF10 knockdown was rescued by ectopic expression of constitutively activated RhoA. Multinucleated cells were not increased upon ARHGEF10 knockdown in contrast to treatment with Y-27632, a specific pharmacological inhibitor for the RhoA effector kinase ROCK, which induced not only multipolar spindle formation, but also multinucleation. Therefore, unregulated centrosome duplication rather than aberration in cytokinesis may be responsible for ARHGEF10 knockdown-dependent multipolar spindle formation. We further isolated the kinesin-like motor protein KIF3B as a binding partner of ARHGEF10. Knockdown of KIF3B again caused multipolar spindle phenotypes. The supernumerary centrosome phenotype was also observed in S phase-arrested osteosarcoma U2OS cells when the expression of ARHGEF10, RhoA or KIF3B was abrogated by RNA interference. Conclusion Collectively, our results suggest that a novel RhoA-dependent signaling pathway under the control of ARHGEF10 has a pivotal role in the regulation of the cell division cycle. This pathway is not involved in

  19. EFHC1, a protein mutated in juvenile myoclonic epilepsy, associates with the mitotic spindle through its N-terminus

    International Nuclear Information System (INIS)

    Nijs, Laurence de; Lakaye, Bernard; Coumans, Bernard; Leon, Christine; Ikeda, Takashi; Delgado-Escueta, Antonio V.; Grisar, Thierry; Chanas, Grazyna

    2006-01-01

    A novel gene, EFHC1, mutated in juvenile myoclonic epilepsy (JME) encodes a protein with three DM10 domains of unknown function and one putative EF-hand motif. To study the properties of EFHC1, we expressed EGFP-tagged protein in various cell lines. In interphase cells, the fusion protein was present in the cytoplasm and in the nucleus with specific accumulation at the centrosome. During mitosis EGFP-EFHC1 colocalized with the mitotic spindle, especially at spindle poles and with the midbody during cytokinesis. Using a specific antibody, we demonstrated the same distribution of the endogenous protein. Deletion analyses revealed that the N-terminal region of EFHC1 is crucial for the association with the mitotic spindle and the midbody. Our results suggest that EFHC1 could play an important role during cell division

  20. NUP98 fusion oncoproteins promote aneuploidy by attenuating the mitotic spindle checkpoint.

    Science.gov (United States)

    Salsi, Valentina; Ferrari, Silvia; Gorello, Paolo; Fantini, Sebastian; Chiavolelli, Francesca; Mecucci, Cristina; Zappavigna, Vincenzo

    2014-02-15

    NUP98 is a recurrent fusion partner in chromosome translocations that cause acute myelogenous leukemia. NUP98, a nucleoporin, and its interaction partner Rae1, have been implicated in the control of chromosome segregation, but their mechanistic contributions to tumorigenesis have been unclear. Here, we show that expression of NUP98 fusion oncoproteins causes mitotic spindle defects and chromosome missegregation, correlating with the capability of NUP98 fusions to cause premature securin degradation and slippage from an unsatisfied spindle assembly checkpoint (SAC). NUP98 fusions, unlike wild-type NUP98, were found to physically interact with the anaphase promoting complex/cyclosome (APC/C)(Cdc20) and to displace the BubR1 SAC component, suggesting a possible mechanistic basis for their interference with SAC function. In addition, NUP98 oncoproteins displayed a prolonged half-life in cells. We found that NUP98 stability is controlled by a PEST sequence, absent in NUP98 oncoproteins, whose deletion reproduced the aberrant SAC-interfering activity of NUP98 oncoproteins. Together, our findings suggest that NUP98 oncoproteins predispose myeloid cells to oncogenic transformation or malignant progression by promoting whole chromosome instability. ©2013 AACR.

  1. Mitotic Spindle Positioning in the EMS Cell of Caenorhabditis elegans Requires LET-99 and LIN-5/NuMA.

    Science.gov (United States)

    Liro, Małgorzata J; Rose, Lesilee S

    2016-11-01

    Asymmetric divisions produce daughter cells with different fates, and thus are critical for animal development. During asymmetric divisions, the mitotic spindle must be positioned on a polarized axis to ensure the differential segregation of cell fate determinants into the daughter cells. In many cell types, a cortically localized complex consisting of Gα, GPR-1/2, and LIN-5 (Gαi/Pins/Mud, Gαi/LGN/NuMA) mediates the recruitment of dynactin/dynein, which exerts pulling forces on astral microtubules to physically position the spindle. The conserved PAR polarity proteins are known to regulate both cytoplasmic asymmetry and spindle positioning in many cases. However, spindle positioning also occurs in response to cell signaling cues that appear to be PAR-independent. In the four-cell Caenorhabditis elegans embryo, Wnt and Mes-1/Src-1 signaling pathways act partially redundantly to align the spindle on the anterior/posterior axis of the endomesodermal (EMS) precursor cell. It is unclear how those extrinsic signals individually contribute to spindle positioning and whether either pathway acts via conserved spindle positioning regulators. Here, we genetically test the involvement of Gα, LIN-5, and their negative regulator LET-99, in transducing EMS spindle positioning polarity cues. We also examined whether the C. elegans ortholog of another spindle positioning regulator, DLG-1, is required. We show that LET-99 acts in the Mes-1/Src-1 pathway for spindle positioning. LIN-5 is also required for EMS spindle positioning, possibly through a Gα- and DLG-1-independent mechanism. Copyright © 2016 by the Genetics Society of America.

  2. Ric-8A and Gi alpha recruit LGN, NuMA, and dynein to the cell cortex to help orient the mitotic spindle.

    Science.gov (United States)

    Woodard, Geoffrey E; Huang, Ning-Na; Cho, Hyeseon; Miki, Toru; Tall, Gregory G; Kehrl, John H

    2010-07-01

    In model organisms, resistance to inhibitors of cholinesterase 8 (Ric-8), a G protein alpha (G alpha) subunit guanine nucleotide exchange factor (GEF), functions to orient mitotic spindles during asymmetric cell divisions; however, whether Ric-8A has any role in mammalian cell division is unknown. We show here that Ric-8A and G alpha(i) function to orient the metaphase mitotic spindle of mammalian adherent cells. During mitosis, Ric-8A localized at the cell cortex, spindle poles, centromeres, central spindle, and midbody. Pertussis toxin proved to be a useful tool in these studies since it blocked the binding of Ric-8A to G alpha(i), thus preventing its GEF activity for G alpha(i). Linking Ric-8A signaling to mammalian cell division, treatment of cells with pertussis toxin, reduction of Ric-8A expression, or decreased G alpha(i) expression similarly affected metaphase cells. Each treatment impaired the localization of LGN (GSPM2), NuMA (microtubule binding nuclear mitotic apparatus protein), and dynein at the metaphase cell cortex and disturbed integrin-dependent mitotic spindle orientation. Live cell imaging of HeLa cells expressing green fluorescent protein-tubulin also revealed that reduced Ric-8A expression prolonged mitosis, caused occasional mitotic arrest, and decreased mitotic spindle movements. These data indicate that Ric-8A signaling leads to assembly of a cortical signaling complex that functions to orient the mitotic spindle.

  3. A mitotic kinesin-6, Pav-KLP, mediates interdependent cortical reorganization and spindle dynamics in Drosophila embryos.

    Science.gov (United States)

    Sommi, Patrizia; Ananthakrishnan, Revathi; Cheerambathur, Dhanya K; Kwon, Mijung; Morales-Mulia, Sandra; Brust-Mascher, Ingrid; Mogilner, Alex

    2010-06-01

    We investigated the role of Pav-KLP, a kinesin-6, in the coordination of spindle and cortical dynamics during mitosis in Drosophila embryos. In vitro, Pav-KLP behaves as a dimer. In vivo, it localizes to mitotic spindles and furrows. Inhibition of Pav-KLP causes defects in both spindle dynamics and furrow ingression, as well as causing changes in the distribution of actin and vesicles. Thus, Pav-KLP stabilizes the spindle by crosslinking interpolar microtubule bundles and contributes to actin furrow formation possibly by transporting membrane vesicles, actin and/or actin regulatory molecules along astral microtubules. Modeling suggests that furrow ingression during cellularization depends on: (1) a Pav-KLP-dependent force driving an initial slow stage of ingression; and (2) the subsequent Pav-KLP-driven transport of actin- and membrane-containing vesicles to the furrow during a fast stage of ingression. We hypothesize that Pav-KLP is a multifunctional mitotic motor that contributes both to bundling of interpolar microtubules, thus stabilizing the spindle, and to a biphasic mechanism of furrow ingression by pulling down the furrow and transporting vesicles that deliver new material to the descending furrow.

  4. Taxifolin enhances andrographolide-induced mitotic arrest and apoptosis in human prostate cancer cells via spindle assembly checkpoint activation.

    Directory of Open Access Journals (Sweden)

    Zhong Rong Zhang

    Full Text Available Andrographolide (Andro suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC, alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

  5. Taxifolin Enhances Andrographolide-Induced Mitotic Arrest and Apoptosis in Human Prostate Cancer Cells via Spindle Assembly Checkpoint Activation

    Science.gov (United States)

    Wong, Matthew Man-Kin; Chiu, Sung-Kay; Cheung, Hon-Yeung

    2013-01-01

    Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC. PMID:23382917

  6. Taxifolin enhances andrographolide-induced mitotic arrest and apoptosis in human prostate cancer cells via spindle assembly checkpoint activation.

    Science.gov (United States)

    Zhang, Zhong Rong; Al Zaharna, Mazen; Wong, Matthew Man-Kin; Chiu, Sung-Kay; Cheung, Hon-Yeung

    2013-01-01

    Andrographolide (Andro) suppresses proliferation and triggers apoptosis in many types of cancer cells. Taxifolin (Taxi) has been proposed to prevent cancer development similar to other dietary flavonoids. In the present study, the cytotoxic and apoptotic effects of the addition of Andro alone and Andro and Taxi together on human prostate carcinoma DU145 cells were assessed. Andro inhibited prostate cancer cell proliferation by mitotic arrest and activation of the intrinsic apoptotic pathway. Although the effect of Taxi alone on DU145 cell proliferation was not significant, the combined use of Taxi with Andro significantly potentiated the anti-proliferative effect of increased mitotic arrest and apoptosis by enhancing the cleavage of poly(ADP-ribose) polymerase, and caspases-7 and -9. Andro together with Taxi enhanced microtubule polymerization in vitro, and they induced the formation of twisted and elongated spindles in the cancer cells, thus leading to mitotic arrest. In addition, we showed that depletion of MAD2, a component in the spindle assembly checkpoint (SAC), alleviated the mitotic block induced by the two compounds, suggesting that they trigger mitotic arrest by SAC activation. This study suggests that the anti-cancer activity of Andro can be significantly enhanced in combination with Taxi by disrupting microtubule dynamics and activating the SAC.

  7. aPKC phosphorylates NuMA-related LIN-5 to position the mitotic spindle during asymmetric division.

    Science.gov (United States)

    Galli, Matilde; Muñoz, Javier; Portegijs, Vincent; Boxem, Mike; Grill, Stephan W; Heck, Albert J R; van den Heuvel, Sander

    2011-08-21

    The position of the mitotic spindle controls the plane of cell cleavage and determines whether polarized cells divide symmetrically or asymmetrically. In animals, an evolutionarily conserved pathway of LIN-5 (homologues: Mud and NuMA), GPR-1/2 (homologues: Pins, LGN, AGS-3) and Gα mediates spindle positioning, and acts downstream of the conserved PAR-3-PAR-6-aPKC polarity complex. However, molecular interactions between polarity proteins and LIN-5-GPR-Gα remain to be identified. Here we describe a quantitative mass spectrometry approach for in vivo identification of protein kinase substrates. Applying this strategy to Caenorhabditis elegans embryos, we found that depletion of the polarity kinase PKC-3 results in markedly decreased levels of phosphorylation of a cluster of four LIN-5 serine residues. These residues are directly phosphorylated by PKC-3 in vitro. Phospho-LIN-5 co-localizes with PKC-3 at the anterior cell cortex and temporally coincides with a switch from anterior- to posterior-directed spindle movements in the one-cell embryo. LIN-5 mutations that prevent phosphorylation increase the extent of anterior-directed spindle movements, whereas phosphomimetic mutations decrease spindle migration. Our results indicate that anterior-located PKC-3 inhibits cortical microtubule pulling forces through direct phosphorylation of LIN-5. This molecular interaction between polarity and spindle-positioning proteins may be used broadly in cell cleavage plane determination.

  8. Inhibition of TRIP1/S8/hSug1, a component of the human 19S proteasome, enhances mitotic apoptosis induced by spindle poisons.

    Science.gov (United States)

    Yamada, Hiroshi Y; Gorbsky, Gary J

    2006-01-01

    Mitotic spindle poisons (e.g., Taxol and vinblastine), used as chemotherapy drugs, inhibit mitotic spindle function, activate the mitotic spindle checkpoint, arrest cells in mitosis, and then cause cell death by mechanisms that are poorly understood. By expression cloning, we identified a truncated version of human TRIP1 (also known as S8, hSug1), an AAA (ATPases associated with diverse cellular activities) family ATPase subunit of the 19S proteasome regulatory complex, as an enhancer of spindle poison-mediated apoptosis. Stable expression of the truncated TRIP1/S8/hSug1 in HeLa cells [OP-TRIP1(88-406)] resulted in a decrease of measurable cellular proteasome activity, indicating that OP-TRIP1(88-406) had a dominant-negative effect on proteasome function. OP-TRIP1(88-406) revealed an increased apoptotic response after treatment with spindle poisons or with proteasome inhibitors. The increased apoptosis coincided with a significant decrease in expression of BubR1, a kinase required for activation and maintenance of the mitotic spindle checkpoint in response to treatment with spindle poisons. Small interfering RNA (siRNA)-mediated knockdown of TRIP1/S8/hSug1 resulted in a reduction of general proteasome activity and an increase in mitotic index. The siRNA treatment also caused increased cell death after spindle poison treatment. These results indicate that inhibition of TRIP1/S8/hSug1 function by expression of a truncated version of the protein or by siRNA-mediated suppression enhances cell death in response to spindle poison treatment. Current proteasome inhibitor drugs in trial as anticancer agents target elements of the 20S catalytic subcomplex. Our results suggest that targeting the ATPase subunits in 19S regulatory complex in the proteasome may enhance the antitumor effects of spindle poisons.

  9. LGN blocks the ability of NuMA to bind and stabilize microtubules. A mechanism for mitotic spindle assembly regulation.

    Science.gov (United States)

    Du, Quansheng; Taylor, Laura; Compton, Duane A; Macara, Ian G

    2002-11-19

    LGN is closely related to a Drosophila protein, Partner of inscuteable (Pins), which is required for polarity establishment and asymmetric cell divisions during embryonic development. In mammalian cells, LGN binds with high affinity to the C-terminal tail of NuMA, a large nuclear protein that is required for spindle organization, and accumulates at the spindle poles during mitosis. LGN also regulates spindle organization, possibly through inhibition of NuMA function, but the mechanism of this effect has not yet been understood. Using mammalian cells, frog egg extracts, and in vitro assays, we now show that a small domain within the C terminus of NuMA stabilizes microtubules (MTs), and that LGN blocks stabilization. The nuclear localization signal adjacent to this domain is not involved in stabilization. NuMA can interact directly with MTs, and the MT binding domain on NuMA overlaps by ten amino acid residues with the LGN binding domain. We therefore propose that a simple steric exclusion model can explain the inhibitory effect of LGN on NuMA-dependent mitotic spindle organization.

  10. Antibodies to mitotic spindle apparatus: clinical significance of NuMA and HsEg5 autoantibodies.

    Science.gov (United States)

    Mozo, Lourdes; Gutiérrez, Carmen; Gómez, Jesús

    2008-07-01

    The clinical associations of NuMA and HsEg5 antibodies, the main anti-mitotic spindle apparatus autoantibodies, remain unclear due to their extremely low prevalence. We have analysed the clinical data of 40 anti-NuMA- (0.87 per thousand) and 7 anti-HsEg5- (0.15 per thousand) positive patients detected during routine immunofluorescence examination of 45,804 sera. NuMA reactivity was further confirmed by immunoblotting. Antibodies to HsEg5 did not associate with any specific pathology. NuMA positivity associated with a diagnosis of connective tissue disease (CTD) in 18 patients (45%), primary Sjögren or sicca syndrome and undifferentiated connective tissue disease being the most represented. Seven patients (17.5%) were diagnosed with different organ-specific autoimmune diseases, whereas in the other 15 patients (37.5%), no autoimmune pathology could be documented. Therefore, although both anti-mitotic spindle apparatus antibodies are not associated to a defined autoimmune pathology, the presence of NuMA antibodies, mainly at high titers, may be an indication for a more extensive screening of CTD.

  11. The small molecule SI113 synergizes with mitotic spindle poisons in arresting the growth of human glioblastoma multiforme

    Science.gov (United States)

    Abbruzzese, Claudia; Catalogna, Giada; Gallo, Enzo; di Martino, Simona; Mileo, Anna M.; Carosi, Mariantonia; Dattilo, Vincenzo; Schenone, Silvia; Musumeci, Francesca; Lavia, Patrizia; Perrotti, Nicola; Amato, Rosario; Paggi, Marco G.

    2017-01-01

    Glioblastoma multiforme (GBM) is the deadliest brain tumor. State-of-art GBM therapy often fails to ensure control of a disease characterized by high frequency of recurrences and progression. In search for novel therapeutic approaches, we assayed the effect of compounds from a cancer drug library on the ADF GBM cell line, establishing their elevated sensitivity to mitotic spindle poisons. Our previous work showed that the effectiveness of the spindle poison paclitaxel in inhibiting cancer cell growth was dependent on the expression of RANBP1, a regulatory target of the serine/threonine kinase SGK1. Recently, we developed the small molecule SI113 to inhibit SGK1 activity. Therefore, we explored the outcome of the association between SI113 and selected spindle poisons, finding that these drugs generated a synergistic cytotoxic effect in GBM cells, drastically reducing their viability and clonogenic capabilities in vitro, as well as inhibiting tumor growth in vivo. We also defined the molecular bases of such a synergistic effect. Because SI113 displays low systemic toxicity, yet strong activity in potentiating the effect of radiotherapy in GBM cells, we believe that this drug could be a strong candidate for clinical trials, with the aim to add it to the current GBM therapeutic approaches. PMID:29340013

  12. The small molecule SI113 synergizes with mitotic spindle poisons in arresting the growth of human glioblastoma multiforme.

    Science.gov (United States)

    Abbruzzese, Claudia; Catalogna, Giada; Gallo, Enzo; di Martino, Simona; Mileo, Anna M; Carosi, Mariantonia; Dattilo, Vincenzo; Schenone, Silvia; Musumeci, Francesca; Lavia, Patrizia; Perrotti, Nicola; Amato, Rosario; Paggi, Marco G

    2017-12-19

    Glioblastoma multiforme (GBM) is the deadliest brain tumor. State-of-art GBM therapy often fails to ensure control of a disease characterized by high frequency of recurrences and progression. In search for novel therapeutic approaches, we assayed the effect of compounds from a cancer drug library on the ADF GBM cell line, establishing their elevated sensitivity to mitotic spindle poisons. Our previous work showed that the effectiveness of the spindle poison paclitaxel in inhibiting cancer cell growth was dependent on the expression of RANBP1, a regulatory target of the serine/threonine kinase SGK1. Recently, we developed the small molecule SI113 to inhibit SGK1 activity. Therefore, we explored the outcome of the association between SI113 and selected spindle poisons, finding that these drugs generated a synergistic cytotoxic effect in GBM cells, drastically reducing their viability and clonogenic capabilities in vitro , as well as inhibiting tumor growth in vivo . We also defined the molecular bases of such a synergistic effect. Because SI113 displays low systemic toxicity, yet strong activity in potentiating the effect of radiotherapy in GBM cells, we believe that this drug could be a strong candidate for clinical trials, with the aim to add it to the current GBM therapeutic approaches.

  13. Nup62, associated with spindle microtubule rather than spindle matrix, is involved in chromosome alignment and spindle assembly during mitosis.

    Science.gov (United States)

    Wu, Zhige; Jin, Zhihua; Zhang, Xinhong; Shen, Na; Wang, Jinbo; Zhao, Yingxian; Mei, Lehe

    2016-09-01

    An increasing number of the active mitotic functions of nucleoporins in the distinct steps of mitosis have been assigned over the past few years. As one of FG-repeats containing nucleoporins, Nup62 has been found to be involved in nuclear transport, cell migration, virus infection, and cell cycle regulation. However, the role and mechanism of Nup62 in mitotic regulation have not been fully revealed. In this paper, it was revealed that a fraction of Nup62 was associated with mitotic spindle microtubule instead of spindle matrix, and the localization of Nup62 in the mitotic spindle depended on its three coiled-coil domains rather than Crm1, although Nup62 strongly interacted with Crm1 during mitosis. Moreover, depletion of Nup62 by small interference of RNA seriously induced the defects of chromosome alignment and spindle assembly although the bipolar spindle was observed in most of the Nup62 knock-down cells. Notably, congression of polar chromosome defect was observed in more than 30% of Nup62 knock-down cells. These findings revealed that Nup62 was a novel mitotic spindle associated nucleoporin and involved in chromosome alignment and spindle assembly. © 2016 International Federation for Cell Biology.

  14. Cross-talk between Aurk-A and Plk1 in mitotic entry and spindle assembly

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    Italia Anna Asteriti

    2015-12-01

    Full Text Available The Aurk-A kinase is involved in different aspects of mitotic control, from mitotic entry to cytokinesis. Consistent with its pleiotropic roles, several Aurk-A interactors are able to modulate its activity, the best characterised being the microtubule binding protein TPX2, the centrosomal protein Cep192 and Bora. Bora has been described as an essential cofactor of Aurk-A for phosphorylation-mediated activation of the mitotic kinase Plk1 at the G2/M transition. A complex Aurk-A/Plk1 signalling axis is emerging, with multiple involved actors; recent data suggest that this control network is not restricted to mitotic entry only, but operates throughout mitosis. Here, we integrate available data from the literature to depict the complex interplay between Aurk-A and Plk1 in G2 and mitosis and how it contributes to their mitotic functions. We will particularly focus on how the activity of specifically localized Aurk-A/Plk1 pools is modulated in time and space by their reciprocal regulation, to ensure the timely and coordinated unfolding of downstream mitotic events.

  15. SAP-like domain in nucleolar spindle associated protein mediates mitotic chromosome loading as well as interphase chromatin interaction

    Energy Technology Data Exchange (ETDEWEB)

    Verbakel, Werner, E-mail: werner.verbakel@chem.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium); Carmeliet, Geert, E-mail: geert.carmeliet@med.kuleuven.be [Laboratory of Experimental Medicine and Endocrinology, Katholieke Universiteit Leuven, Herestraat 49, Bus 902, 3000 Leuven (Belgium); Engelborghs, Yves, E-mail: yves.engelborghs@fys.kuleuven.be [Laboratory of Biomolecular Dynamics, Katholieke Universiteit Leuven, Celestijnenlaan 200G, Bus 2403, 3001 Heverlee (Belgium)

    2011-08-12

    Highlights: {yields} The SAP-like domain in NuSAP is a functional DNA-binding domain with preference for dsDNA. {yields} This SAP-like domain is essential for chromosome loading during early mitosis. {yields} NuSAP is highly dynamic on mitotic chromatin, as evident from photobleaching experiments. {yields} The SAP-like domain also mediates NuSAP-chromatin interaction in interphase nucleoplasm. -- Abstract: Nucleolar spindle associated protein (NuSAP) is a microtubule-stabilizing protein that localizes to chromosome arms and chromosome-proximal microtubules during mitosis and to the nucleus, with enrichment in the nucleoli, during interphase. The critical function of NuSAP is underscored by the finding that its depletion in HeLa cells results in various mitotic defects. Moreover, NuSAP is found overexpressed in multiple cancers and its expression levels often correlate with the aggressiveness of cancer. Due to its localization on chromosome arms and combination of microtubule-stabilizing and DNA-binding properties, NuSAP takes a special place within the extensive group of spindle assembly factors. In this study, we identify a SAP-like domain that shows DNA binding in vitro with a preference for dsDNA. Deletion of the SAP-like domain abolishes chromosome arm binding of NuSAP during mitosis, but is not sufficient to abrogate its chromosome-proximal localization after anaphase onset. Fluorescence recovery after photobleaching experiments revealed the highly dynamic nature of this NuSAP-chromatin interaction during mitosis. In interphase cells, NuSAP also interacts with chromatin through its SAP-like domain, as evident from its enrichment on dense chromatin regions and intranuclear mobility, measured by fluorescence correlation spectroscopy. The obtained results are in agreement with a model where NuSAP dynamically stabilizes newly formed microtubules on mitotic chromosomes to enhance chromosome positioning without immobilizing these microtubules. Interphase Nu

  16. SAP-like domain in nucleolar spindle associated protein mediates mitotic chromosome loading as well as interphase chromatin interaction

    International Nuclear Information System (INIS)

    Verbakel, Werner; Carmeliet, Geert; Engelborghs, Yves

    2011-01-01

    Highlights: → The SAP-like domain in NuSAP is a functional DNA-binding domain with preference for dsDNA. → This SAP-like domain is essential for chromosome loading during early mitosis. → NuSAP is highly dynamic on mitotic chromatin, as evident from photobleaching experiments. → The SAP-like domain also mediates NuSAP-chromatin interaction in interphase nucleoplasm. -- Abstract: Nucleolar spindle associated protein (NuSAP) is a microtubule-stabilizing protein that localizes to chromosome arms and chromosome-proximal microtubules during mitosis and to the nucleus, with enrichment in the nucleoli, during interphase. The critical function of NuSAP is underscored by the finding that its depletion in HeLa cells results in various mitotic defects. Moreover, NuSAP is found overexpressed in multiple cancers and its expression levels often correlate with the aggressiveness of cancer. Due to its localization on chromosome arms and combination of microtubule-stabilizing and DNA-binding properties, NuSAP takes a special place within the extensive group of spindle assembly factors. In this study, we identify a SAP-like domain that shows DNA binding in vitro with a preference for dsDNA. Deletion of the SAP-like domain abolishes chromosome arm binding of NuSAP during mitosis, but is not sufficient to abrogate its chromosome-proximal localization after anaphase onset. Fluorescence recovery after photobleaching experiments revealed the highly dynamic nature of this NuSAP-chromatin interaction during mitosis. In interphase cells, NuSAP also interacts with chromatin through its SAP-like domain, as evident from its enrichment on dense chromatin regions and intranuclear mobility, measured by fluorescence correlation spectroscopy. The obtained results are in agreement with a model where NuSAP dynamically stabilizes newly formed microtubules on mitotic chromosomes to enhance chromosome positioning without immobilizing these microtubules. Interphase NuSAP-chromatin interaction

  17. Cohesion fatigue explains why pharmacological inhibition of the APC/C induces a spindle checkpoint-dependent mitotic arrest.

    Directory of Open Access Journals (Sweden)

    Pablo Lara-Gonzalez

    Full Text Available The Spindle Assembly Checkpoint (SAC delays the onset of anaphase in response to unattached kinetochores by inhibiting the activity of the Anaphase-Promoting Complex/Cyclosome (APC/C, an E3 ubiquitin ligase. Once all the chromosomes have bioriented, SAC signalling is somehow silenced, which allows progression through mitosis. Recent studies suggest that the APC/C itself participates in SAC silencing by targeting an unknown factor for proteolytic degradation. Key evidence in favour of this model comes from the use of proTAME, a small molecule inhibitor of the APC/C. In cells, proTAME causes a mitotic arrest that is SAC-dependent. Even though this observation comes at odds with the current view that the APC/C acts downstream of the SAC, it was nonetheless argued that these results revealed a role for APC/C activity in SAC silencing. However, we show here that the mitotic arrest induced by proTAME is due to the induction of cohesion fatigue, a phenotype that is caused by the loss of sister chromatid cohesion following a prolonged metaphase. Under these conditions, the SAC is re-activated and APC/C inhibition is maintained independently of proTAME. Therefore, these results provide a simpler explanation for why the proTAME-induced mitotic arrest is also dependent on the SAC. While these observations question the notion that the APC/C is required for SAC silencing, we nevertheless show that APC/C activity does partially contribute to its own release from inhibitory complexes, and importantly, this does not depend on proteasome-mediated degradation.

  18. Mitotic Spindle Asymmetry: A Wnt/PCP-Regulated Mechanism Generating Asymmetrical Division in Cortical Precursors

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    Delphine Delaunay

    2014-01-01

    Full Text Available The regulation of asymmetric cell division (ACD during corticogenesis is incompletely understood. We document that spindle-size asymmetry (SSA between the two poles occurs during corticogenesis and parallels ACD. SSA appears at metaphase and is maintained throughout division, and we show it is necessary for proper neurogenesis. Imaging of spindle behavior and division outcome reveals that neurons preferentially arise from the larger-spindle pole. Mechanistically, SSA magnitude is controlled by Wnt7a and Vangl2, both members of the Wnt/planar cell polarity (PCP-signaling pathway, and relayed to the cell cortex by P-ERM proteins. In vivo, Vangl2 and P-ERM downregulation promotes early cell-cycle exit and prevents the proper generation of late-born neurons. Thus, SSA is a core component of ACD that is conserved in invertebrates and vertebrates and plays a key role in the tight spatiotemporal control of self-renewal and differentiation during mammalian corticogenesis.

  19. Taxane-mediated radiosensitization derives from chromosomal missegregation on tripolar mitotic spindles orchestrated by AURKA and TPX2.

    Science.gov (United States)

    Orth, M; Unger, K; Schoetz, U; Belka, C; Lauber, K

    2018-01-04

    Taxane-based radiochemotherapy is a central treatment option for various cancer entities in locally advanced stages. The therapeutic synergism of this combined modality approach due to taxane-mediated radiosensitization of cancer cells is well-known. However, the underlying molecular mechanisms remain largely elusive, and mechanism-derived predictive markers of taxane-based radiochemotherapy are currently not available. Here, we show that clinically relevant doses of Paclitaxel, the prototype taxane, stimulate a tripolar mode of mitosis leading to chromosomal missegregation and aneuploidization rather than interfering with cell cycle progression. This distinct mitotic phenotype was interlinked with Paclitaxel-mediated radiosensitization via overexpression of mitotic Aurora kinase A (AURKA) and its cofactor TPX2 whose knockdown rescued the bipolar mode of cell division and largely attenuated the radiosensitizing effects of Paclitaxel. In the cancer genome atlas (TCGA) lung adenocarcinoma cohort, high expression levels of AURKA and TPX2 were associated with specifically improved overall survival upon taxane-based radiochemotherapy, but not in case of non-taxane-based radiochemotherapy, chemo- or radiotherapy only. Thus, our data provide insights into Paclitaxel-mediated radiosensitization on a mechanistic and molecular level and identify AURKA and TPX2 as the first potential mechanism-based, predictive markers of taxane-based radiochemotherapy.

  20. Hydrogen peroxide prolongs mitotic arrest in a dose dependent manner and independently of the spindle assembly checkpoint activity in Saccharomyces cerevisiae.

    Science.gov (United States)

    Atalay, Pinar Buket; Asci, Oyku; Kaya, Fatih Oner; Tuna, Bilge Guvenc

    2017-12-01

    Oxidative stress and chromosome missegregation are important factors that are linked to aneuploidy. A major reason for chromosome missegragation is the inappropriate activity of the spindle assembly checkpoint (SAC), a conserved surveillance mechanism that monitors the state of kinetochore-microtubule attachments to ensure equal chromosome segregation in mitosis. SAC-activation induces a prolonged mitotic arrest. Mitosis is considered the most vulnerable cell cycle phase to several external signals, therefore increasing the time cells spent in this phase via mitotic arrest induction by SAC-activating agents is favorable for cancer therapy. Cancer cells also display elevated oxidative stress due to abnormally high production of reactive oxygen species (ROS). However, the effect of increased oxidative stress on the duration of mitotic arrest remains largely unknown. In this study, we investigated the effect of H 2 O 2 -induced oxidative stress on the mitotic arrest induced by a SAC-activating agent (nocodazole) in Saccharomyces cerevisiae. Our data suggest that oxidative stress prolongs SAC-activation induced mitotic arrest in a dose dependent manner. We, in addition, investigated the effect of H 2 O 2 treatment on the mitotic arrest induced independently of SAC-activation by using a conditional mutant (cdc23) and showed that the effect of H 2 O 2 -induced oxidative stress on mitotic arrest is independent of the SAC activity.

  1. Coordination of Cell Cycle Progression and Mitotic Spindle Assembly Involves Histone H3 Lysine 4 Methylation by Set1/COMPASS

    Science.gov (United States)

    Beilharz, Traude H.; Harrison, Paul F.; Miles, Douglas Maya; See, Michael Ming; Le, Uyen Minh Merry; Kalanon, Ming; Curtis, Melissa Jane; Hasan, Qambar; Saksouk, Julie; Margaritis, Thanasis; Holstege, Frank; Geli, Vincent; Dichtl, Bernhard

    2017-01-01

    Methylation of histone H3 lysine 4 (H3K4) by Set1 complex/COMPASS is a hallmark of eukaryotic chromatin, but it remains poorly understood how this post-translational modification contributes to the regulation of biological processes like the cell cycle. Here, we report a H3K4 methylation-dependent pathway in Saccharomyces cerevisiae that governs toxicity toward benomyl, a microtubule destabilizing drug. Benomyl-sensitive growth of wild-type cells required mono- and dimethylation of H3K4 and Pho23, a PHD-containing subunit of the Rpd3L complex. Δset1 and Δpho23 deletions suppressed defects associated with ipl1-2 aurora kinase mutant, an integral component of the spindle assembly checkpoint during mitosis. Benomyl resistance of Δset1 strains was accompanied by deregulation of all four tubulin genes and the phenotype was suppressed by tub2-423 and Δtub3 mutations, establishing a genetic link between H3K4 methylation and microtubule function. Most interestingly, sine wave fitting and clustering of transcript abundance time series in synchronized cells revealed a requirement for Set1 for proper cell-cycle-dependent gene expression and Δset1 cells displayed delayed entry into S phase. Disruption of G1/S regulation in Δmbp1 and Δswi4 transcription factor mutants duplicated both benomyl resistance and suppression of ipl1-2 as was observed with Δset1. Taken together our results support a role for H3K4 methylation in the coordination of cell-cycle progression and proper assembly of the mitotic spindle during mitosis. PMID:28049706

  2. Mammalian neurogenesis requires Treacle-Plk1 for precise control of spindle orientation, mitotic progression, and maintenance of neural progenitor cells.

    Science.gov (United States)

    Sakai, Daisuke; Dixon, Jill; Dixon, Michael J; Trainor, Paul A

    2012-01-01

    The cerebral cortex is a specialized region of the brain that processes cognitive, motor, somatosensory, auditory, and visual functions. Its characteristic architecture and size is dependent upon the number of neurons generated during embryogenesis and has been postulated to be governed by symmetric versus asymmetric cell divisions, which mediate the balance between progenitor cell maintenance and neuron differentiation, respectively. The mechanistic importance of spindle orientation remains controversial, hence there is considerable interest in understanding how neural progenitor cell mitosis is controlled during neurogenesis. We discovered that Treacle, which is encoded by the Tcof1 gene, is a novel centrosome- and kinetochore-associated protein that is critical for spindle fidelity and mitotic progression. Tcof1/Treacle loss-of-function disrupts spindle orientation and cell cycle progression, which perturbs the maintenance, proliferation, and localization of neural progenitors during cortical neurogenesis. Consistent with this, Tcof1(+/-) mice exhibit reduced brain size as a consequence of defects in neural progenitor maintenance. We determined that Treacle elicits its effect via a direct interaction with Polo-like kinase1 (Plk1), and furthermore we discovered novel in vivo roles for Plk1 in governing mitotic progression and spindle orientation in the developing mammalian cortex. Increased asymmetric cell division, however, did not promote increased neuronal differentiation. Collectively our research has therefore identified Treacle and Plk1 as novel in vivo regulators of spindle fidelity, mitotic progression, and proliferation in the maintenance and localization of neural progenitor cells. Together, Treacle and Plk1 are critically required for proper cortical neurogenesis, which has important implications in the regulation of mammalian brain size and the pathogenesis of congenital neurodevelopmental disorders such as microcephaly.

  3. Mammalian neurogenesis requires Treacle-Plk1 for precise control of spindle orientation, mitotic progression, and maintenance of neural progenitor cells.

    Directory of Open Access Journals (Sweden)

    Daisuke Sakai

    Full Text Available The cerebral cortex is a specialized region of the brain that processes cognitive, motor, somatosensory, auditory, and visual functions. Its characteristic architecture and size is dependent upon the number of neurons generated during embryogenesis and has been postulated to be governed by symmetric versus asymmetric cell divisions, which mediate the balance between progenitor cell maintenance and neuron differentiation, respectively. The mechanistic importance of spindle orientation remains controversial, hence there is considerable interest in understanding how neural progenitor cell mitosis is controlled during neurogenesis. We discovered that Treacle, which is encoded by the Tcof1 gene, is a novel centrosome- and kinetochore-associated protein that is critical for spindle fidelity and mitotic progression. Tcof1/Treacle loss-of-function disrupts spindle orientation and cell cycle progression, which perturbs the maintenance, proliferation, and localization of neural progenitors during cortical neurogenesis. Consistent with this, Tcof1(+/- mice exhibit reduced brain size as a consequence of defects in neural progenitor maintenance. We determined that Treacle elicits its effect via a direct interaction with Polo-like kinase1 (Plk1, and furthermore we discovered novel in vivo roles for Plk1 in governing mitotic progression and spindle orientation in the developing mammalian cortex. Increased asymmetric cell division, however, did not promote increased neuronal differentiation. Collectively our research has therefore identified Treacle and Plk1 as novel in vivo regulators of spindle fidelity, mitotic progression, and proliferation in the maintenance and localization of neural progenitor cells. Together, Treacle and Plk1 are critically required for proper cortical neurogenesis, which has important implications in the regulation of mammalian brain size and the pathogenesis of congenital neurodevelopmental disorders such as microcephaly.

  4. The mesh is a network of microtubule connectors that stabilizes individual kinetochore fibers of the mitotic spindle.

    Science.gov (United States)

    Nixon, Faye M; Gutiérrez-Caballero, Cristina; Hood, Fiona E; Booth, Daniel G; Prior, Ian A; Royle, Stephen J

    2015-06-19

    Kinetochore fibers (K-fibers) of the mitotic spindle are force-generating units that power chromosome movement during mitosis. K-fibers are composed of many microtubules that are held together throughout their length. Here, we show, using 3D electron microscopy, that K-fiber microtubules (MTs) are connected by a network of MT connectors. We term this network 'the mesh'. The K-fiber mesh is made of linked multipolar connectors. Each connector has up to four struts, so that a single connector can link up to four MTs. Molecular manipulation of the mesh by overexpression of TACC3 causes disorganization of the K-fiber MTs. Optimal stabilization of K-fibers by the mesh is required for normal progression through mitosis. We propose that the mesh stabilizes K-fibers by pulling MTs together and thereby maintaining the integrity of the fiber. Our work thus identifies the K-fiber meshwork of linked multipolar connectors as a key integrator and determinant of K-fiber structure and function.

  5. The accuracy of survival time prediction for patients with glioma is improved by measuring mitotic spindle checkpoint gene expression.

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    Li Bie

    Full Text Available Identification of gene expression changes that improve prediction of survival time across all glioma grades would be clinically useful. Four Affymetrix GeneChip datasets from the literature, containing data from 771 glioma samples representing all WHO grades and eight normal brain samples, were used in an ANOVA model to screen for transcript changes that correlated with grade. Observations were confirmed and extended using qPCR assays on RNA derived from 38 additional glioma samples and eight normal samples for which survival data were available. RNA levels of eight major mitotic spindle assembly checkpoint (SAC genes (BUB1, BUB1B, BUB3, CENPE, MAD1L1, MAD2L1, CDC20, TTK significantly correlated with glioma grade and six also significantly correlated with survival time. In particular, the level of BUB1B expression was highly correlated with survival time (p<0.0001, and significantly outperformed all other measured parameters, including two standards; WHO grade and MIB-1 (Ki-67 labeling index. Measurement of the expression levels of a small set of SAC genes may complement histological grade and other clinical parameters for predicting survival time.

  6. Antagonistic spindle motors and MAPs regulate metaphase spindle length and chromosome segregation.

    Science.gov (United States)

    Syrovatkina, Viktoriya; Fu, Chuanhai; Tran, Phong T

    2013-12-02

    Metaphase describes a phase of mitosis where chromosomes are attached and oriented on the bipolar spindle for subsequent segregation at anaphase. In diverse cell types, the metaphase spindle is maintained at characteristic constant length [1-3]. Metaphase spindle length is proposed to be regulated by a balance of pushing and pulling forces generated by distinct sets of spindle microtubules (MTs) and their interactions with motors and MT-associated proteins (MAPs). Spindle length is further proposed to be important for chromosome segregation fidelity, as cells with shorter- or longer-than-normal metaphase spindles, generated through deletion or inhibition of individual mitotic motors or MAPs, showed chromosome segregation defects. To test the force-balance model of spindle length control and its effect on chromosome segregation, we applied fast microfluidic temperature control with live-cell imaging to monitor the effect of deleting or switching off different combinations of antagonistic force contributors in the fission yeast metaphase spindle. We show that the spindle midzone proteins kinesin-5 cut7p and MT bundler ase1p contribute to outward-pushing forces and that the spindle kinetochore proteins kinesin-8 klp5/6p and dam1p contribute to inward-pulling forces. Removing these proteins individually led to aberrant metaphase spindle length and chromosome segregation defects. Removing these proteins in antagonistic combination rescued the defective spindle length and in some combinations also partially rescued chromosome segregation defects. Copyright © 2013 Elsevier Ltd. All rights reserved.

  7. Phyllanthus emblica Fruit Extract Activates Spindle Assembly Checkpoint, Prevents Mitotic Aberrations and Genomic Instability in Human Colon Epithelial NCM460 Cells

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    Xihan Guo

    2016-09-01

    Full Text Available The fruit of Phyllanthus emblica Linn. (PE has been widely consumed as a functional food and folk medicine in Southeast Asia due to its remarkable nutritional and pharmacological effects. Previous research showed PE delays mitotic progress and increases genomic instability (GIN in human colorectal cancer cells. This study aimed to investigate the similar effects of PE by the biomarkers related to spindle assembly checkpoint (SAC, mitotic aberrations and GIN in human NCM460 normal colon epithelial cells. Cells were treated with PE and harvested differently according to the biomarkers observed. Frequencies of micronuclei (MN, nucleoplasmic bridge (NPB and nuclear bud (NB in cytokinesis-block micronucleus assay were used as indicators of GIN. Mitotic aberrations were assessed by the biomarkers of chromosome misalignment, multipolar division, chromosome lagging and chromatin bridge. SAC activity was determined by anaphase-to- metaphase ratio (AMR and the expression of core SAC gene budding uninhibited by benzimidazoles related 1 (BubR1. Compared with the control, PE-treated cells showed (1 decreased incidences of MN, NPB and NB (p < 0.01; (2 decreased frequencies of all mitotic aberration biomarkers (p < 0.01; and (3 decreased AMR (p < 0.01 and increased BubR1 expression (p < 0.001. The results revealed PE has the potential to protect human normal colon epithelial cells from mitotic and genomic damages partially by enhancing the function of SAC.

  8. Role of mitotic motors, dynein and kinesin, in the induction of abnormal centrosome integrity and multipolar spindles in cultured V79 cells exposed to dimethylarsinic acid.

    Science.gov (United States)

    Ochi, Takafumi

    2002-01-29

    The role of microtubule-based motors in the induction of abnormal centrosome integrity by dimethylarsinic acid (DMAA) was investigated with the use of monastrol, a specific inhibitor of mitotic kinesin, and vanadate, an inhibitor of dynein ATPase. Cytoplasmic dynein co-localized with multiple foci of gamma-tubulin in mitotic cells arrested by DMAA. Disruption of microtubules caused dispersion of dynein while multiple foci of gamma-tubulin were coalesced to a single dot. Vanadate also caused dispersion of dynein, which had been co-localized with multiple foci of gamma-tubulin by DMAA, without affecting spindle organization. However, the dispersion of dynein did not prohibit the induction of abnormal centrosome integrity by DMAA. Inhibition of mitotic kinesin by monastrol resulted in monoastral cells with non-migrated centrosomes in the cell center. Monastrol, when applied to mitotic cells with abnormal centrosome integrity, rapidly reduced the incidence of cells with the centrosome abnormality. Moreover, monastrol completely inhibited reorganization of abnormal centrosomes that had been coalesced to a single dot by microtubule disruption. These results suggest that abnormal centrosome integrity caused by DMAA is not simply due to dispersion of fragments of microtubule-organizing centers, but is dependent on the action of kinesin. In addition, the results suggest that kinesin plays a role not only in the induction of mitotic centrosome abnormality, but also in maintenance.

  9. The NIMA Kinase Is Required To Execute Stage-Specific Mitotic Functions after Initiation of Mitosis

    Science.gov (United States)

    Govindaraghavan, Meera; Lad, Alisha A.

    2014-01-01

    The G2-M transition in Aspergillus nidulans requires the NIMA kinase, the founding member of the Nek kinase family. Inactivation of NIMA results in a late G2 arrest, while overexpression of NIMA is sufficient to promote mitotic events independently of cell cycle phase. Endogenously tagged NIMA-GFP has dynamic mitotic localizations appearing first at the spindle pole body and then at nuclear pore complexes before transitioning to within nuclei and the mitotic spindle and back at the spindle pole bodies at mitotic exit, suggesting that it functions sequentially at these locations. Since NIMA is indispensable for mitotic entry, it has been difficult to determine the requirement of NIMA for subaspects of mitosis. We show here that when NIMA is partially inactivated, although mitosis can be initiated, a proportion of cells fail to successfully generate two daughter nuclei. We further define the mitotic defects to show that normal NIMA function is required for the formation of a bipolar spindle, nuclear pore complex disassembly, completion of chromatin segregation, and the normal structural rearrangements of the nuclear envelope required to generate two nuclei from one. In the remaining population of cells that enter mitosis with inadequate NIMA, two daughter nuclei are generated in a manner dependent on the spindle assembly checkpoint, indicating highly penetrant defects in mitotic progression without sufficient NIMA activity. This study shows that NIMA is required not only for mitotic entry but also sequentially for successful completion of stage-specific mitotic events. PMID:24186954

  10. Mitotic spindle function in Saccharomyces cerevisiae requires a balance between different types of kinesin-related motors.

    Science.gov (United States)

    Saunders, W; Lengyel, V; Hoyt, M A

    1997-06-01

    Two Saccharomyces cerevisiae kinesin-related motors, Cin8p and Kip1p, perform an essential role in the separation of spindle poles during spindle assembly and a major role in spindle elongation. Cin8p and Kip1p are also required to prevent an inward spindle collapse prior to anaphase. A third kinesin-related motor, Kar3p, may act antagonistically to Cin8p and Kip1p since loss of Kar3p partially suppresses the spindle collapse in cin8 kip1 mutants. We have tested the relationship between Cin8p and Kar3p by overexpressing both motors using the inducible GAL1 promoter. Overexpression of KAR3 results in a shrinkage of spindle size and a temperature-dependent inhibition of the growth of wild-type cells. Excess Kar3p has a stronger inhibitory effect on the growth of cin8 kip1 mutants and can completely block anaphase spindle elongation in these cells. In contrast, overexpression of CIN8 leads to premature spindle elongation in all cells tested. This is the first direct demonstration of antagonistic motors acting on the intact spindle and suggests that spindle length is determined by the relative activity of Kar3p-like and Cin8p/Kip1p-like motors.

  11. Fission yeast cells undergo nuclear division in the absence of spindle microtubules.

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    Stefania Castagnetti

    2010-10-01

    Full Text Available Mitosis in eukaryotic cells employs spindle microtubules to drive accurate chromosome segregation at cell division. Cells lacking spindle microtubules arrest in mitosis due to a spindle checkpoint that delays mitotic progression until all chromosomes have achieved stable bipolar attachment to spindle microtubules. In fission yeast, mitosis occurs within an intact nuclear membrane with the mitotic spindle elongating between the spindle pole bodies. We show here that in fission yeast interference with mitotic spindle formation delays mitosis only briefly and cells proceed to an unusual nuclear division process we term nuclear fission, during which cells perform some chromosome segregation and efficiently enter S-phase of the next cell cycle. Nuclear fission is blocked if spindle pole body maturation or sister chromatid separation cannot take place or if actin polymerization is inhibited. We suggest that this process exhibits vestiges of a primitive nuclear division process independent of spindle microtubules, possibly reflecting an evolutionary intermediate state between bacterial and Archeal chromosome segregation where the nucleoid divides without a spindle and a microtubule spindle-based eukaryotic mitosis.

  12. Gamma-tubulin is required for bipolar spindle assembly and for proper kinetochore microtubule attachments during prometaphase I in Drosophila oocytes.

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    Stacie E Hughes

    2011-08-01

    Full Text Available In many animal species the meiosis I spindle in oocytes is anastral and lacks centrosomes. Previous studies of Drosophila oocytes failed to detect the native form of the germline-specific γ-tubulin (γTub37C in meiosis I spindles, and genetic studies have yielded conflicting data regarding the role of γTub37C in the formation of bipolar spindles at meiosis I. Our examination of living and fixed oocytes carrying either a null allele or strong missense mutation in the γtub37C gene demonstrates a role for γTub37C in the positioning of the oocyte nucleus during late prophase, as well as in the formation and maintenance of bipolar spindles in Drosophila oocytes. Prometaphase I spindles in γtub37C mutant oocytes showed wide, non-tapered spindle poles and disrupted positioning. Additionally, chromosomes failed to align properly on the spindle and showed morphological defects. The kinetochores failed to properly co-orient and often lacked proper attachments to the microtubule bundles, suggesting that γTub37C is required to stabilize kinetochore microtubule attachments in anastral spindles. Although spindle bipolarity was sometimes achieved by metaphase I in both γtub37C mutants, the resulting chromosome masses displayed highly disrupted chromosome alignment. Therefore, our data conclusively demonstrate a role for γTub37C in both the formation of the anastral meiosis I spindle and in the proper attachment of kinetochore microtubules. Finally, multispectral imaging demonstrates the presences of native γTub37C along the length of wild-type meiosis I spindles.

  13. Intercentrosomal angular separation during mitosis plays a crucial role for maintaining spindle stability

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    Sutradhar, S.; Basu, S.; Paul, R.

    2015-10-01

    Cell division through proper spindle formation is one of the key puzzles in cell biology. In most mammalian cells, chromosomes spontaneously arrange to achieve a stable bipolar spindle during metaphase which eventually ensures proper segregation of the DNA into the daughter cells. In this paper, we present a robust three-dimensional mechanistic model to investigate the formation and maintenance of a bipolar mitotic spindle in mammalian cells under different physiological constraints. Using realistic parameters, we test spindle viability by measuring the spindle length and studying the chromosomal configuration. The model strikingly predicts a feature of the spindle instability arising from the insufficient intercentrosomal angular separation and impaired sliding of the interpolar microtubules. In addition, our model successfully reproduces chromosomal patterns observed in mammalian cells, when activity of different motor proteins is perturbed.

  14. Phyllanthus emblica Fruit Extract Activates Spindle Assembly Checkpoint, Prevents Mitotic Aberrations and Genomic Instability in Human Colon Epithelial NCM460 Cells.

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    Guo, Xihan; Wang, Xu

    2016-09-03

    The fruit of Phyllanthus emblica Linn. (PE) has been widely consumed as a functional food and folk medicine in Southeast Asia due to its remarkable nutritional and pharmacological effects. Previous research showed PE delays mitotic progress and increases genomic instability (GIN) in human colorectal cancer cells. This study aimed to investigate the similar effects of PE by the biomarkers related to spindle assembly checkpoint (SAC), mitotic aberrations and GIN in human NCM460 normal colon epithelial cells. Cells were treated with PE and harvested differently according to the biomarkers observed. Frequencies of micronuclei (MN), nucleoplasmic bridge (NPB) and nuclear bud (NB) in cytokinesis-block micronucleus assay were used as indicators of GIN. Mitotic aberrations were assessed by the biomarkers of chromosome misalignment, multipolar division, chromosome lagging and chromatin bridge. SAC activity was determined by anaphase-to- metaphase ratio (AMR) and the expression of core SAC gene budding uninhibited by benzimidazoles related 1 (BubR1). Compared with the control, PE-treated cells showed (1) decreased incidences of MN, NPB and NB (p genomic damages partially by enhancing the function of SAC.

  15. The G-protein regulatory (GPR) motif-containing Leu-Gly-Asn-enriched protein (LGN) and Gialpha3 influence cortical positioning of the mitotic spindle poles at metaphase in symmetrically dividing mammalian cells.

    Science.gov (United States)

    Blumer, Joe B; Kuriyama, Ryoko; Gettys, Thomas W; Lanier, Stephen M

    2006-12-01

    We addressed the role of the G-protein regulatory (GPR) motif-containing Leu-Gly-Asn-enriched protein (LGN) and G-proteins (Gialpha3) in the positioning of the spindle pole during mammalian cell division. Immunocytochemistry indicated that both LGN and Gialpha3 co-localized at the spindle pole and at the midbody and the cell cortex during the different phases of mitosis. In marked contrast to the positioning of the spindle pole at metaphase midway between the cell cortex and the metaphase plate, the spindle pole was juxtaposed with the cell cortex at metaphase following increased expression of Gialpha3 and LGN. This repositioning of the spindle pole required the interaction of LGN with Gialpha. The influence of LGN and Gialpha3 on the cortical positioning of the spindle pole likely reflects either stronger pulling forces on the spindle pole exerted from the cell cortex or increased pushing forces exerted on the spindle pole from the mitotic spindle indicating that these events are regulated by GPR motif-containing proteins and G-proteins independent of asymmetry.

  16. Mitotic spindle defects and chromosome mis-segregation induced by LDL/cholesterol-implications for Niemann-Pick C1, Alzheimer's disease, and atherosclerosis.

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    Antoneta Granic

    Full Text Available Elevated low-density lipoprotein (LDL-cholesterol is a risk factor for both Alzheimer's disease (AD and Atherosclerosis (CVD, suggesting a common lipid-sensitive step in their pathogenesis. Previous results show that AD and CVD also share a cell cycle defect: chromosome instability and up to 30% aneuploidy-in neurons and other cells in AD and in smooth muscle cells in atherosclerotic plaques in CVD. Indeed, specific degeneration of aneuploid neurons accounts for 90% of neuronal loss in AD brain, indicating that aneuploidy underlies AD neurodegeneration. Cell/mouse models of AD develop similar aneuploidy through amyloid-beta (Aß inhibition of specific microtubule motors and consequent disruption of mitotic spindles. Here we tested the hypothesis that, like upregulated Aß, elevated LDL/cholesterol and altered intracellular cholesterol homeostasis also causes chromosomal instability. Specifically we found that: 1 high dietary cholesterol induces aneuploidy in mice, satisfying the hypothesis' first prediction, 2 Niemann-Pick C1 patients accumulate aneuploid fibroblasts, neurons, and glia, demonstrating a similar aneugenic effect of intracellular cholesterol accumulation in humans 3 oxidized LDL, LDL, and cholesterol, but not high-density lipoprotein (HDL, induce chromosome mis-segregation and aneuploidy in cultured cells, including neuronal precursors, indicating that LDL/cholesterol directly affects the cell cycle, 4 LDL-induced aneuploidy requires the LDL receptor, but not Aß, showing that LDL works differently than Aß, with the same end result, 5 cholesterol treatment disrupts the structure of the mitotic spindle, providing a cell biological mechanism for its aneugenic activity, and 6 ethanol or calcium chelation attenuates lipoprotein-induced chromosome mis-segregation, providing molecular insights into cholesterol's aneugenic mechanism, specifically through its rigidifying effect on the cell membrane, and potentially explaining why ethanol

  17. Drosophila parthenogenesis: A tool to decipher centrosomal vs acentrosomal spindle assembly pathways

    International Nuclear Information System (INIS)

    Riparbelli, Maria Giovanna; Callaini, Giuliano

    2008-01-01

    Development of unfertilized eggs in the parthenogenetic strain K23-O-im of Drosophila mercatorum requires the stochastic interactions of self-assembled centrosomes with the female chromatin. In a portion of the unfertilized eggs that do not assemble centrosomes, microtubules organize a bipolar anastral mitotic spindle around the chromatin like the one formed during the first female meiosis, suggesting that similar pathways may be operative. In the cytoplasm of eggs in which centrosomes do form, monastral and biastral spindles are found. Analysis by laser scanning confocal microscopy suggests that these spindles are derived from the stochastic interaction of astral microtubules directly with kinetochore regions or indirectly with kinetochore microtubules. Our findings are consistent with the idea that mitotic spindle assembly requires both acentrosomal and centrosomal pathways, strengthening the hypothesis that astral microtubules can dictate the organization of the spindle by capturing kinetochore microtubules

  18. Nuclear inner membrane fusion facilitated by yeast Jem1p is required for spindle pole body fusion but not for the first mitotic nuclear division during yeast mating.

    Science.gov (United States)

    Nishikawa, Shuh-ichi; Hirata, Aiko; Endo, Toshiya

    2008-11-01

    During mating of budding yeast, Saccharomyces cerevisiae, two haploid nuclei fuse to produce a diploid nucleus. The process of nuclear fusion requires two J proteins, Jem1p in the endoplasmic reticulum (ER) lumen and Sec63p, which forms a complex with Sec71p and Sec72p, in the ER membrane. Zygotes of mutants defective in the functions of Jem1p or Sec63p contain two haploid nuclei that were closely apposed but failed to fuse. Here we analyzed the ultrastructure of nuclei in jem1 Delta and sec71 Delta mutant zygotes using electron microscope with the freeze-substituted fixation method. Three-dimensional reconstitution of nuclear structures from electron microscope serial sections revealed that Jem1p facilitates nuclear inner-membrane fusion and spindle pole body (SPB) fusion while Sec71p facilitates nuclear outer-membrane fusion. Two haploid SPBs that failed to fuse could duplicate, and mitotic nuclear division of the unfused haploid nuclei started in jem1 Delta and sec71 Delta mutant zygotes. This observation suggests that nuclear inner-membrane fusion is required for SPB fusion, but not for SPB duplication in the first mitotic cell division.

  19. Live imaging of spindle pole disorganization in docetaxel-treated multicolor cells

    International Nuclear Information System (INIS)

    Sakaushi, Shinji; Nishida, Kumi; Minamikawa, Harumi; Fukada, Takashi; Oka, Shigenori; Sugimoto, Kenji

    2007-01-01

    Treatment of cells with docetaxel at low concentrations induces aberrant bipolar spindles of which two centrosomes stay at only one pole, and also induces multipolar spindles. To gain insight into the relations between centrosome impairment and structural defects of the spindle, live-cell imaging was performed on a human MDA Auro/imp/H3 cell line in which centrosomes/mitotic spindles, nuclear membrane and chromatin were simultaneously visualized by fluorescent proteins. In the presence of docetaxel at IC 50 concentration, the centrosomes did not segregate, and multiple aster-like structures ectopically arose around the disappearing nuclear membrane. Those ectopic structures formed an acentrosomal pole opposing to the two-centrosomes-containing pole. In late metaphase, one pole often fragmented into multiple spindle poles, leading multipolar division. These results suggest that spindle pole fragility may be induced by centrosome impairment, and collapse of the pole may contribute to induction of aneuploid daughter cells

  20. ATP-competitive inhibitors of the mitotic kinesin KSP that function via an allosteric mechanism.

    Science.gov (United States)

    Luo, Lusong; Parrish, Cynthia A; Nevins, Neysa; McNulty, Dean E; Chaudhari, Amita M; Carson, Jeffery D; Sudakin, Valery; Shaw, Antony N; Lehr, Ruth; Zhao, Huizhen; Sweitzer, Sharon; Lad, Latesh; Wood, Kenneth W; Sakowicz, Roman; Annan, Roland S; Huang, Pearl S; Jackson, Jeffrey R; Dhanak, Dashyant; Copeland, Robert A; Auger, Kurt R

    2007-11-01

    The mitotic kinesin KSP (kinesin spindle protein, or Eg5) has an essential role in centrosome separation and formation of the bipolar mitotic spindle. Its exclusive involvement in the mitotic spindle of proliferating cells presents an opportunity for developing new anticancer agents with reduced side effects relative to antimitotics that target tubulin. Ispinesib is an allosteric small-molecule KSP inhibitor in phase 2 clinical trials. Mutations that attenuate ispinesib binding to KSP have been identified, which highlights the need for inhibitors that target different binding sites. We describe a new class of selective KSP inhibitors that are active against ispinesib-resistant forms of KSP. These ATP-competitive KSP inhibitors do not bind in the nucleotide binding pocket. Cumulative data from generation of resistant cells, site-directed mutagenesis and photo-affinity labeling suggest that they compete with ATP binding via a novel allosteric mechanism.

  1. Complex Commingling: Nucleoporins and the Spindle Assembly Checkpoint

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    Ikram Mossaid

    2015-11-01

    Full Text Available The segregation of the chromosomes during mitosis is an important process, in which the replicated DNA content is properly allocated into two daughter cells. To ensure their genomic integrity, cells present an essential surveillance mechanism known as the spindle assembly checkpoint (SAC, which monitors the bipolar attachment of the mitotic spindle to chromosomes to prevent errors that would result in chromosome mis-segregation and aneuploidy. Multiple components of the nuclear pore complex (NPC, a gigantic protein complex that forms a channel through the nuclear envelope to allow nucleocytoplasmic exchange of macromolecules, were shown to be critical for faithful cell division and implicated in the regulation of different steps of the mitotic process, including kinetochore and spindle assembly as well as the SAC. In this review, we will describe current knowledge about the interconnection between the NPC and the SAC in an evolutional perspective, which primarily relies on the two mitotic checkpoint regulators, Mad1 and Mad2. We will further discuss the role of NPC constituents, the nucleoporins, in kinetochore and spindle assembly and the formation of the mitotic checkpoint complex during mitosis and interphase.

  2. Diverse mitotic functions of the cytoskeletal cross-linking protein Shortstop suggest a role in Dynein/Dynactin activity

    Science.gov (United States)

    Dewey, Evan B.; Johnston, Christopher A.

    2017-01-01

    Proper assembly and orientation of the bipolar mitotic spindle is critical to the fidelity of cell division. Mitotic precision fundamentally contributes to cell fate specification, tissue development and homeostasis, and chromosome distribution within daughter cells. Defects in these events are thought to contribute to several human diseases. The underlying mechanisms that function in spindle morphogenesis and positioning remain incompletely defined, however. Here we describe diverse roles for the actin-microtubule cross-linker Shortstop (Shot) in mitotic spindle function in Drosophila. Shot localizes to mitotic spindle poles, and its knockdown results in an unfocused spindle pole morphology and a disruption of proper spindle orientation. Loss of Shot also leads to chromosome congression defects, cell cycle progression delay, and defective chromosome segregation during anaphase. These mitotic errors trigger apoptosis in Drosophila epithelial tissue, and blocking this apoptotic response results in a marked induction of the epithelial–mesenchymal transition marker MMP-1. The actin-binding domain of Shot directly interacts with Actin-related protein-1 (Arp-1), a key component of the Dynein/Dynactin complex. Knockdown of Arp-1 phenocopies Shot loss universally, whereas chemical disruption of F-actin does so selectively. Our work highlights novel roles for Shot in mitosis and suggests a mechanism involving Dynein/Dynactin activation. PMID:28747439

  3. Formation of spindle poles by dynein/dynactin-dependent transport of NuMA.

    Science.gov (United States)

    Merdes, A; Heald, R; Samejima, K; Earnshaw, W C; Cleveland, D W

    2000-05-15

    NuMA is a large nuclear protein whose relocation to the spindle poles is required for bipolar mitotic spindle assembly. We show here that this process depends on directed NuMA transport toward microtubule minus ends powered by cytoplasmic dynein and its activator dynactin. Upon nuclear envelope breakdown, large cytoplasmic aggregates of green fluorescent protein (GFP)-tagged NuMA stream poleward along spindle fibers in association with the actin-related protein 1 (Arp1) protein of the dynactin complex and cytoplasmic dynein. Immunoprecipitations and gel filtration demonstrate the assembly of a reversible, mitosis-specific complex of NuMA with dynein and dynactin. NuMA transport is required for spindle pole assembly and maintenance, since disruption of the dynactin complex (by increasing the amount of the dynamitin subunit) or dynein function (with an antibody) strongly inhibits NuMA translocation and accumulation and disrupts spindle pole assembly.

  4. From meiosis to mitosis - the sperm centrosome defines the kinetics of spindle assembly after fertilization in Xenopus.

    Science.gov (United States)

    Cavazza, Tommaso; Peset, Isabel; Vernos, Isabelle

    2016-07-01

    Bipolar spindle assembly in the vertebrate oocyte relies on a self-organization chromosome-dependent pathway. Upon fertilization, the male gamete provides a centrosome, and the first and subsequent embryonic divisions occur in the presence of duplicated centrosomes that act as dominant microtubule organizing centres (MTOCs). The transition from meiosis to embryonic mitosis involves a necessary adaptation to integrate the dominant chromosome-dependent pathway with the centrosomes to form the bipolar spindle. Here, we took advantage of the Xenopus laevis egg extract system to mimic in vitro the assembly of the first embryonic spindle and investigate the respective contributions of the centrosome and the chromosome-dependent pathway to the kinetics of the spindle bipolarization. We found that centrosomes control the transition from the meiotic to the mitotic spindle assembly mechanism. By defining the kinetics of spindle bipolarization, the centrosomes ensure their own positioning to each spindle pole and thereby their essential correct inheritance to the two first daughter cells of the embryo for the development of a healthy organism. © 2016. Published by The Company of Biologists Ltd.

  5. Asymmetric Centriole Numbers at Spindle Poles Cause Chromosome Missegregation in Cancer

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    Marco R. Cosenza

    2017-08-01

    Full Text Available Chromosomal instability is a hallmark of cancer and correlates with the presence of extra centrosomes, which originate from centriole overduplication. Overduplicated centrioles lead to the formation of centriole rosettes, which mature into supernumerary centrosomes in the subsequent cell cycle. While extra centrosomes promote chromosome missegregation by clustering into pseudo-bipolar spindles, the contribution of centriole rosettes to chromosome missegregation is unknown. We used multi-modal imaging of cells with conditional centriole overduplication to show that mitotic rosettes in bipolar spindles frequently harbor unequal centriole numbers, leading to biased chromosome capture that favors binding to the prominent pole. This results in chromosome missegregation and aneuploidy. Rosette mitoses lead to viable offspring and significantly contribute to progeny production. We further show that centrosome abnormalities in primary human malignancies frequently consist of centriole rosettes. As asymmetric centriole rosettes generate mitotic errors that can be propagated, rosette mitoses are sufficient to cause chromosome missegregation in cancer.

  6. Cell and molecular biology of spindle poles and NuMA.

    Science.gov (United States)

    Fant, Xavier; Merdes, Andreas; Haren, Laurence

    2004-01-01

    Mitotic and meiotic cells contain a bipolar spindle apparatus of microtubules and associated proteins. To arrange microtubules into focused spindle poles, different mechanisms are used by various organisms. Principally, two major pathways have been characterized: nucleation and anchorage of microtubules at preexisting centers such as centrosomes or spindle pole bodies, or microtubule growth off the surface of chromosomes, followed by sorting and focusing into spindle poles. These two mechanisms can even be found in cells of the same organism: whereas most somatic animal cells utilize the centrosome as an organizing center for spindle microtubules, female meiotic cells build an acentriolar spindle apparatus. Most interestingly, the molecular components that drive acentriolar spindle pole formation are also present in cells containing centrosomes. They include microtubule-dependent motor proteins and a variety of structural proteins that regulate microtubule orientation, anchoring, and stability. The first of these spindle pole proteins, NuMA, had already been identified more than 20 years ago. In addition, several new proteins have been characterized more recently. This review discusses their role during spindle formation and their regulation in the cell cycle.

  7. Cooperation Between Kinesin Motors Promotes Spindle Symmetry and Chromosome Organization in Oocytes.

    Science.gov (United States)

    Radford, Sarah J; Go, Allysa Marie M; McKim, Kim S

    2017-02-01

    The oocyte spindle in most animal species is assembled in the absence of the microtubule-organizing centers called centrosomes. Without the organization provided by centrosomes, acentrosomal meiotic spindle organization may rely heavily on the bundling of microtubules by kinesin motor proteins. Indeed, the minus-end directed kinesin-14 NCD, and the plus-end directed kinesin-6 Subito are known to be required for oocyte spindle organization in Drosophila melanogaster How multiple microtubule-bundling kinesins interact to produce a functional acentrosomal spindle is not known. In addition, there have been few studies on the meiotic function of one of the most important microtubule-bundlers in mitotic cells, the kinesin-5 KLP61F. We have found that the kinesin-5 KLP61F is required for spindle and centromere symmetry in oocytes. The asymmetry observed in the absence of KLP61F depends on NCD, the kinesin-12 KLP54D, and the microcephaly protein ASP. In contrast, KLP61F and Subito work together in maintaining a bipolar spindle. We propose that the prominent central spindle, stabilized by Subito, provides the framework for the coordination of multiple microtubule-bundling activities. The activities of several proteins, including NCD, KLP54D, and ASP, generate asymmetries within the acentrosomal spindle, while KLP61F and Subito balance these forces, resulting in the capacity to accurately segregate chromosomes. Copyright © 2017 by the Genetics Society of America.

  8. PTEN regulates EG5 to control spindle architecture and chromosome congression during mitosis

    Science.gov (United States)

    He, Jinxue; Zhang, Zhong; Ouyang, Meng; Yang, Fan; Hao, Hongbo; Lamb, Kristy L.; Yang, Jingyi; Yin, Yuxin; Shen, Wen H.

    2016-01-01

    Architectural integrity of the mitotic spindle is required for efficient chromosome congression and accurate chromosome segregation to ensure mitotic fidelity. Tumour suppressor PTEN has multiple functions in maintaining genome stability. Here we report an essential role of PTEN in mitosis through regulation of the mitotic kinesin motor EG5 for proper spindle architecture and chromosome congression. PTEN depletion results in chromosome misalignment in metaphase, often leading to catastrophic mitotic failure. In addition, metaphase cells lacking PTEN exhibit defects of spindle geometry, manifested prominently by shorter spindles. PTEN is associated and co-localized with EG5 during mitosis. PTEN deficiency induces aberrant EG5 phosphorylation and abrogates EG5 recruitment to the mitotic spindle apparatus, leading to spindle disorganization. These data demonstrate the functional interplay between PTEN and EG5 in controlling mitotic spindle structure and chromosome behaviour during mitosis. We propose that PTEN functions to equilibrate mitotic phosphorylation for proper spindle formation and faithful genomic transmission. PMID:27492783

  9. Multipolar spindle pole coalescence is a major source of kinetochore mis-attachment and chromosome mis-segregation in cancer cells.

    Directory of Open Access Journals (Sweden)

    William T Silkworth

    Full Text Available Many cancer cells display a CIN (Chromosome Instability phenotype, by which they exhibit high rates of chromosome loss or gain at each cell cycle. Over the years, a number of different mechanisms, including mitotic spindle multipolarity, cytokinesis failure, and merotelic kinetochore orientation, have been proposed as causes of CIN. However, a comprehensive theory of how CIN is perpetuated is still lacking. We used CIN colorectal cancer cells as a model system to investigate the possible cellular mechanism(s underlying CIN. We found that CIN cells frequently assembled multipolar spindles in early mitosis. However, multipolar anaphase cells were very rare, and live-cell experiments showed that almost all CIN cells divided in a bipolar fashion. Moreover, fixed-cell analysis showed high frequencies of merotelically attached lagging chromosomes in bipolar anaphase CIN cells, and higher frequencies of merotelic attachments in multipolar vs. bipolar prometaphases. Finally, we found that multipolar CIN prometaphases typically possessed gamma-tubulin at all spindle poles, and that a significant fraction of bipolar metaphase/early anaphase CIN cells possessed more than one centrosome at a single spindle pole. Taken together, our data suggest a model by which merotelic kinetochore attachments can easily be established in multipolar prometaphases. Most of these multipolar prometaphase cells would then bi-polarize before anaphase onset, and the residual merotelic attachments would produce chromosome mis-segregation due to anaphase lagging chromosomes. We propose this spindle pole coalescence mechanism as a major contributor to chromosome instability in cancer cells.

  10. Pten regulates spindle pole movement through Dlg1-mediated recruitment of Eg5 to centrosomes.

    Science.gov (United States)

    van Ree, Janine H; Nam, Hyun-Ja; Jeganathan, Karthik B; Kanakkanthara, Arun; van Deursen, Jan M

    2016-07-01

    Phosphatase and tensin homologue (Pten) suppresses neoplastic growth by negatively regulating PI(3)K signalling through its phosphatase activity. To gain insight into the actions of non-catalytic Pten domains in normal physiological processes and tumorigenesis, we engineered mice lacking the PDZ-binding domain (PDZ-BD). Here, we show that the PDZ-BD regulates centrosome movement and that its heterozygous or homozygous deletion promotes aneuploidy and tumour formation. We found that Pten is recruited to pre-mitotic centrosomes in a Plk1-dependent fashion to create a docking site for protein complexes containing the PDZ-domain-containing protein Dlg1 (also known as Sap97) and Eg5 (also known as Kif11), a kinesin essential for centrosome movement and bipolar spindle formation. Docking of Dlg1-Eg5 complexes to Pten depended on Eg5 phosphorylation by the Nek9-Nek6 mitotic kinase cascade and Cdk1. PDZ-BD deletion or Dlg1 ablation impaired loading of Eg5 onto centrosomes and spindle pole motility, yielding asymmetrical spindles that are prone to chromosome missegregation. Collectively, these data demonstrate that Pten, through the Dlg1-binding ability of its PDZ-BD, accumulates phosphorylated Eg5 at duplicated centrosomes to establish symmetrical bipolar spindles that properly segregate chromosomes, and suggest that this function contributes to tumour suppression.

  11. New mitotic regulators released from chromatin

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    Hideki eYokoyama

    2013-12-01

    Full Text Available Faithful action of the mitotic spindle segregates duplicated chromosomes into daughter cells. Perturbations of this process result in chromosome mis-segregation, leading to chromosomal instability and cancer development. Chromosomes are not simply passengers segregated by spindle microtubules but rather play a major active role in spindle assembly. The GTP bound form of the Ran GTPase (RanGTP, produced around chromosomes, locally activates spindle assembly factors. Recent studies have uncovered that chromosomes organize mitosis beyond spindle formation. They distinctly regulate other mitotic events, such as spindle maintenance in anaphase, which is essential for chromosome segregation. Furthermore, the direct function of chromosomes is not only to produce RanGTP but, in addition, to release key mitotic regulators from chromatin. Chromatin-remodeling factors and nuclear pore complex proteins, which have established functions on chromatin in interphase, dissociate from mitotic chromatin and function in spindle assembly or maintenance. Thus, chromosomes actively organize their own segregation using chromatin-releasing mitotic regulators as well as RanGTP.

  12. Requirements for NuMA in maintenance and establishment of mammalian spindle poles.

    Science.gov (United States)

    Silk, Alain D; Holland, Andrew J; Cleveland, Don W

    2009-03-09

    Microtubules of the mitotic spindle in mammalian somatic cells are focused at spindle poles, a process thought to include direct capture by astral microtubules of kinetochores and/or noncentrosomally nucleated microtubule bundles. By construction and analysis of a conditional loss of mitotic function allele of the nuclear mitotic apparatus (NuMA) protein in mice and cultured primary cells, we demonstrate that NuMA is an essential mitotic component with distinct contributions to the establishment and maintenance of focused spindle poles. When mitotic NuMA function is disrupted, centrosomes provide initial focusing activity, but continued centrosome attachment to spindle fibers under tension is defective, and the maintenance of focused kinetochore fibers at spindle poles throughout mitosis is prevented. Without centrosomes and NuMA, initial establishment of spindle microtubule focusing completely fails. Thus, NuMA is a defining feature of the mammalian spindle pole and functions as an essential tether linking bulk microtubules of the spindle to centrosomes.

  13. The chromosomal basis of meiotic acentrosomal spindle assembly and function in oocytes.

    Science.gov (United States)

    Radford, Sarah J; Nguyen, Alexandra L; Schindler, Karen; McKim, Kim S

    2017-06-01

    Several aspects of meiosis are impacted by the absence of centrosomes in oocytes. Here, we review four aspects of meiosis I that are significantly affected by the absence of centrosomes in oocyte spindles. One, microtubules tend to assemble around the chromosomes. Two, the organization of these microtubules into a bipolar spindle is directed by the chromosomes. Three, chromosome bi-orientation and attachment to microtubules from the correct pole require modification of the mechanisms used in mitotic cells. Four, chromosome movement to the poles at anaphase cannot rely on polar anchoring of spindle microtubules by centrosomes. Overall, the chromosomes are more active participants during acentrosomal spindle assembly in oocytes, compared to mitotic and male meiotic divisions where centrosomes are present. The chromosomes are endowed with information that can direct the meiotic divisions and dictate their own behavior in oocytes. Processes beyond those known from mitosis appear to be required for their bi-orientation at meiosis I. As mitosis occurs without centrosomes in many systems other than oocytes, including all plants, the concepts discussed here may not be limited to oocytes. The study of meiosis in oocytes has revealed mechanisms that are operating in mitosis and will probably continue to do so.

  14. The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis

    International Nuclear Information System (INIS)

    Salmela, Anna-Leena; Pouwels, Jeroen; Kukkonen-Macchi, Anu; Waris, Sinikka; Toivonen, Pauliina; Jaakkola, Kimmo; Mäki-Jouppila, Jenni; Kallio, Lila; Kallio, Marko J.

    2012-01-01

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule–kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3′,5-dihydroxy-4′,6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule–kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

  15. The flavonoid eupatorin inactivates the mitotic checkpoint leading to polyploidy and apoptosis

    Energy Technology Data Exchange (ETDEWEB)

    Salmela, Anna-Leena [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Graduate School of Biomedical Sciences, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Pouwels, Jeroen; Kukkonen-Macchi, Anu [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Waris, Sinikka; Toivonen, Pauliina [Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Jaakkola, Kimmo [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Maeki-Jouppila, Jenni [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Drug Discovery Graduate School, University of Turku (Finland); Kallio, Lila, E-mail: lila.kallio@vtt.fi [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Kallio, Marko J. [VTT Technical Research Centre of Finland, Medical Biotechnology, P.O. Box 106, Turku (Finland); Turku Centre for Biotechnology, P.O. Box 123, University of Turku (Finland); Centre of Excellence for Translational Genome-Scale Biology, P.O. Box 106, Academy of Finland (Finland)

    2012-03-10

    The spindle assembly checkpoint (SAC) is a conserved mechanism that ensures the fidelity of chromosome distribution in mitosis by preventing anaphase onset until the correct bipolar microtubule-kinetochore attachments are formed. Errors in SAC function may contribute to tumorigenesis by inducing numerical chromosome anomalies (aneuploidy). On the other hand, total disruption of SAC can lead to massive genomic imbalance followed by cell death, a phenomena that has therapeutic potency. We performed a cell-based high-throughput screen with a compound library of 2000 bioactives for novel SAC inhibitors and discovered a plant-derived phenolic compound eupatorin (3 Prime ,5-dihydroxy-4 Prime ,6,7-trimethoxyflavone) as an anti-mitotic flavonoid. The premature override of the microtubule drug-imposed mitotic arrest by eupatorin is dependent on microtubule-kinetochore attachments but not interkinetochore tension. Aurora B kinase activity, which is essential for maintenance of normal SAC signaling, is diminished by eupatorin in cells and in vitro providing a mechanistic explanation for the observed forced mitotic exit. Eupatorin likely has additional targets since eupatorin treatment of pre-mitotic cells causes spindle anomalies triggering a transient M phase delay followed by impaired cytokinesis and polyploidy. Finally, eupatorin potently induces apoptosis in multiple cancer cell lines and suppresses cancer cell proliferation in organotypic 3D cell culture model.

  16. Cytoplasmic MTOCs control spindle orientation for asymmetric cell division in plants.

    Science.gov (United States)

    Kosetsu, Ken; Murata, Takashi; Yamada, Moé; Nishina, Momoko; Boruc, Joanna; Hasebe, Mitsuyasu; Van Damme, Daniël; Goshima, Gohta

    2017-10-17

    Proper orientation of the cell division axis is critical for asymmetric cell divisions that underpin cell differentiation. In animals, centrosomes are the dominant microtubule organizing centers (MTOC) and play a pivotal role in axis determination by orienting the mitotic spindle. In land plants that lack centrosomes, a critical role of a microtubular ring structure, the preprophase band (PPB), has been observed in this process; the PPB is required for orienting (before prophase) and guiding (in telophase) the mitotic apparatus. However, plants must possess additional mechanisms to control the division axis, as certain cell types or mutants do not form PPBs. Here, using live imaging of the gametophore of the moss Physcomitrella patens , we identified acentrosomal MTOCs, which we termed "gametosomes," appearing de novo and transiently in the prophase cytoplasm independent of PPB formation. We show that gametosomes are dispensable for spindle formation but required for metaphase spindle orientation. In some cells, gametosomes appeared reminiscent of the bipolar MT "polar cap" structure that forms transiently around the prophase nucleus in angiosperms. Specific disruption of the polar caps in tobacco cells misoriented the metaphase spindles and frequently altered the final division plane, indicating that they are functionally analogous to the gametosomes. These results suggest a broad use of transient MTOC structures as the spindle orientation machinery in plants, compensating for the evolutionary loss of centrosomes, to secure the initial orientation of the spindle in a spatial window that allows subsequent fine-tuning of the division plane axis by the guidance machinery. Copyright © 2017 the Author(s). Published by PNAS.

  17. Phosphorylation by Cdk1 increases the binding of Eg5 to microtubules in vitro and in Xenopus egg extract spindles.

    Directory of Open Access Journals (Sweden)

    Julie Cahu

    Full Text Available Motor proteins from the kinesin-5 subfamily play an essential role in spindle assembly during cell division of most organisms. These motors crosslink and slide microtubules in the spindle. Kinesin-5 motors are phosphorylated at a conserved site by Cyclin-dependent kinase 1 (Cdk1 during mitosis. Xenopus laevis kinesin-5 has also been reported to be phosphorylated by Aurora A in vitro.We investigate here the effect of these phosphorylations on kinesin-5 from Xenopus laevis, called Eg5. We find that phosphorylation at threonine 937 in the C-terminal tail of Eg5 by Cdk1 does not affect the velocity of Eg5, but strongly increases its binding to microtubules assembled in buffer. Likewise, this phosphorylation promotes binding of Eg5 to microtubules in Xenopus egg extract spindles. This enhancement of binding elevates the amount of Eg5 in spindles above a critical level required for bipolar spindle formation. We find furthermore that phosphorylation of Xenopus laevis Eg5 by Aurora A at serine 543 in the stalk is not required for spindle formation.These results show that phosphorylation of Eg5 by Cdk1 has a direct effect on the interaction of this motor with microtubules. In egg extract, phosphorylation of Eg5 by Cdk1 ensures that the amount of Eg5 in the spindle is above a level that is required for spindle formation. This enhanced targeting to the spindle appears therefore to be, at least in part, a direct consequence of the enhanced binding of Eg5 to microtubules upon phosphorylation by Cdk1. These findings advance our understanding of the regulation of this essential mitotic motor protein.

  18. Evidence for dynein and astral microtubule-mediated cortical release and transport of Gαi/LGN/NuMA complex in mitotic cells.

    Science.gov (United States)

    Zheng, Zhen; Wan, Qingwen; Liu, Jing; Zhu, Huabin; Chu, Xiaogang; Du, Quansheng

    2013-04-01

    Spindle positioning is believed to be governed by the interaction between astral microtubules and the cell cortex and involve cortically anchored motor protein dynein. How dynein is recruited to and regulated at the cell cortex to generate forces on astral microtubules is not clear. Here we show that mammalian homologue of Drosophila Pins (Partner of Inscuteable) (LGN), a Gαi-binding protein that is critical for spindle positioning in different systems, associates with cytoplasmic dynein heavy chain (DYNC1H1) in a Gαi-regulated manner. LGN is required for the mitotic cortical localization of DYNC1H1, which, in turn, also modulates the cortical accumulation of LGN. Using fluorescence recovery after photobleaching analysis, we show that cortical LGN is dynamic and the turnover of LGN relies, at least partially, on astral microtubules and DYNC1H1. We provide evidence for dynein- and astral microtubule-mediated transport of Gαi/LGN/nuclear mitotic apparatus (NuMA) complex from cell cortex to spindle poles and show that actin filaments counteract such transport by maintaining Gαi/LGN/NuMA and dynein at the cell cortex. Our results indicate that astral microtubules are required for establishing bipolar, symmetrical cortical LGN distribution during metaphase. We propose that regulated cortical release and transport of LGN complex along astral microtubules may contribute to spindle positioning in mammalian cells.

  19. Cell death by mitotic catastrophe: a molecular definition

    NARCIS (Netherlands)

    Castedo, M.; Perfettini, J.-L.; Roumier, T.; Andreau, K.; Medema, R.H.; Kroemer, G.

    2004-01-01

    The current literature is devoid of a clearcut definition of mitotic catastrophe, a type of cell death that occurs during mitosis. Here, we propose that mitotic catastrophe results from a combination of deficient cell-cycle checkpoints (in particular the DNA structure checkpoints and the spindle

  20. Targeting TAO Kinases Using a New Inhibitor Compound Delays Mitosis and Induces Mitotic Cell Death in Centrosome Amplified Breast Cancer Cells.

    Science.gov (United States)

    Koo, Chuay-Yeng; Giacomini, Caterina; Reyes-Corral, Marta; Olmos, Yolanda; Tavares, Ignatius A; Marson, Charles M; Linardopoulos, Spiros; Tutt, Andrew N; Morris, Jonathan D H

    2017-11-01

    Thousand-and-one amino acid kinases (TAOK) 1 and 2 are activated catalytically during mitosis and can contribute to mitotic cell rounding and spindle positioning. Here, we characterize a compound that inhibits TAOK1 and TAOK2 activity with IC 50 values of 11 to 15 nmol/L, is ATP-competitive, and targets these kinases selectively. TAOK inhibition or depletion in centrosome-amplified SKBR3 or BT549 breast cancer cell models increases the mitotic population, the percentages of mitotic cells displaying amplified centrosomes and multipolar spindles, induces cell death, and inhibits cell growth. In contrast, nontumorigenic and dividing bipolar MCF-10A breast cells appear less dependent on TAOK activity and can complete mitosis and proliferate in the presence of the TAOK inhibitor. We demonstrate that TAOK1 and TAOK2 localize to the cytoplasm and centrosomes respectively during mitosis. Live cell imaging shows that the TAOK inhibitor prolongs the duration of mitosis in SKBR3 cells, increases mitotic cell death, and reduces the percentages of cells exiting mitosis, whereas MCF-10A cells continue to divide and proliferate. Over 80% of breast cancer tissues display supernumerary centrosomes, and tumor cells frequently cluster extra centrosomes to avoid multipolar mitoses and associated cell death. Consequently, drugs that stimulate centrosome declustering and induce multipolarity are likely to target dividing centrosome-amplified cancer cells preferentially, while sparing normal bipolar cells. Our results demonstrate that TAOK inhibition can enhance centrosome declustering and mitotic catastrophe in cancer cells, and these proteins may therefore offer novel therapeutic targets suitable for drug inhibition and the potential treatment of breast cancers, where supernumerary centrosomes occur. Mol Cancer Ther; 16(11); 2410-21. ©2017 AACR . ©2017 American Association for Cancer Research.

  1. Cell Division: NuMA Bears the Load in the Spindle.

    Science.gov (United States)

    Maiato, Helder; Pereira, António J

    2017-08-07

    The mitotic spindle bears the load of chromosomes during mitosis, but how this load is distributed across the spindle is unclear. A new study shows that load distribution in the spindle is confined and requires the microtubule cross-linking protein NuMA. Copyright © 2017 Elsevier Ltd. All rights reserved.

  2. Mitotic regulation by NIMA-related kinases

    Directory of Open Access Journals (Sweden)

    Blot Joelle

    2007-08-01

    Full Text Available Abstract The NIMA-related kinases represent a family of serine/threonine kinases implicated in cell cycle control. The founding member of this family, the NIMA kinase of Aspergillus nidulans, as well as the fission yeast homologue Fin1, contribute to multiple aspects of mitotic progression including the timing of mitotic entry, chromatin condensation, spindle organization and cytokinesis. Mammals contain a large family of eleven NIMA-related kinases, named Nek1 to Nek11. Of these, there is now substantial evidence that Nek2, Nek6, Nek7 and Nek9 also regulate mitotic events. At least three of these kinases, as well as NIMA and Fin1, have been localized to the microtubule organizing centre of their respective species, namely the centrosome or spindle pole body. Here, they have important functions in microtubule organization and mitotic spindle assembly. Other Nek kinases have been proposed to play microtubule-dependent roles in non-dividing cells, most notably in regulating the axonemal microtubules of cilia and flagella. In this review, we discuss the evidence that NIMA-related kinases make a significant contribution to the orchestration of mitotic progression and thereby protect cells from chromosome instability. Furthermore, we highlight their potential as novel chemotherapeutic targets.

  3. Activity of the kinesin spindle protein inhibitor ispinesib (SB-715992) in models of breast cancer

    Energy Technology Data Exchange (ETDEWEB)

    Purcell, James W; Davis, Jefferson; Reddy, Mamatha; Martin, Shamra; Samayoa, Kimberly; Vo, Hung; Thomsen, Karen; Bean, Peter; Kuo, Wen Lin; Ziyad, Safiyyah; Billig, Jessica; Feiler, Heidi S; Gray, Joe W; Wood, Kenneth W; Cases, Sylvaine

    2009-06-10

    Ispinesib (SB-715992) is a potent inhibitor of kinesin spindle protein (KSP), a kinesin motor protein essential for the formation of a bipolar mitotic spindle and cell cycle progression through mitosis. Clinical studies of ispinesib have demonstrated a 9% response rate in patients with locally advanced or metastatic breast cancer, and a favorable safety profile without significant neurotoxicities, gastrointestinal toxicities or hair loss. To better understand the potential of ispinesib in the treatment of breast cancer we explored the activity of ispinesib alone and in combination several therapies approved for the treatment of breast cancer. We measured the ispinesib sensitivity and pharmacodynamic response of breast cancer cell lines representative of various subtypes in vitro and as xenografts in vivo, and tested the ability of ispinesib to enhance the anti-tumor activity of approved therapies. In vitro, ispinesib displayed broad anti-proliferative activity against a panel of 53 breast cell-lines. In vivo, ispinesib produced regressions in each of five breast cancer models, and tumor free survivors in three of these models. The effects of ispinesib treatment on pharmacodynamic markers of mitosis and apoptosis were examined in vitro and in vivo, revealing a greater increase in both mitotic and apoptotic markers in the MDA-MB-468 model than in the less sensitive BT-474 model. In vivo, ispinesib enhanced the anti-tumor activity of trastuzumab, lapatinib, doxorubicin, and capecitabine, and exhibited activity comparable to paclitaxel and ixabepilone. These findings support further clinical exploration of KSP inhibitors for the treatment of breast cancer.

  4. Structures of actin-like ParM filaments show architecture of plasmid-segregating spindles.

    Science.gov (United States)

    Bharat, Tanmay A M; Murshudov, Garib N; Sachse, Carsten; Löwe, Jan

    2015-07-02

    Active segregation of Escherichia coli low-copy-number plasmid R1 involves formation of a bipolar spindle made of left-handed double-helical actin-like ParM filaments. ParR links the filaments with centromeric parC plasmid DNA, while facilitating the addition of subunits to ParM filaments. Growing ParMRC spindles push sister plasmids to the cell poles. Here, using modern electron cryomicroscopy methods, we investigate the structures and arrangements of ParM filaments in vitro and in cells, revealing at near-atomic resolution how subunits and filaments come together to produce the simplest known mitotic machinery. To understand the mechanism of dynamic instability, we determine structures of ParM filaments in different nucleotide states. The structure of filaments bound to the ATP analogue AMPPNP is determined at 4.3 Å resolution and refined. The ParM filament structure shows strong longitudinal interfaces and weaker lateral interactions. Also using electron cryomicroscopy, we reconstruct ParM doublets forming antiparallel spindles. Finally, with whole-cell electron cryotomography, we show that doublets are abundant in bacterial cells containing low-copy-number plasmids with the ParMRC locus, leading to an asynchronous model of R1 plasmid segregation.

  5. Spatial signals link exit from mitosis to spindle position.

    Science.gov (United States)

    Falk, Jill Elaine; Tsuchiya, Dai; Verdaasdonk, Jolien; Lacefield, Soni; Bloom, Kerry; Amon, Angelika

    2016-05-11

    In budding yeast, if the spindle becomes mispositioned, cells prevent exit from mitosis by inhibiting the mitotic exit network (MEN). The MEN is a signaling cascade that localizes to spindle pole bodies (SPBs) and activates the phosphatase Cdc14. There are two competing models that explain MEN regulation by spindle position. In the 'zone model', exit from mitosis occurs when a MEN-bearing SPB enters the bud. The 'cMT-bud neck model' posits that cytoplasmic microtubule (cMT)-bud neck interactions prevent MEN activity. Here we find that 1) eliminating cMT- bud neck interactions does not trigger exit from mitosis and 2) loss of these interactions does not precede Cdc14 activation. Furthermore, using binucleate cells, we show that exit from mitosis occurs when one SPB enters the bud despite the presence of a mispositioned spindle. We conclude that exit from mitosis is triggered by a correctly positioned spindle rather than inhibited by improper spindle position.

  6. The nuclear mitotic apparatus (NuMA) protein: localization and dynamics in human oocytes, fertilization and early embryos.

    Science.gov (United States)

    Alvarez Sedó, Cristian; Schatten, Heide; Combelles, Catherine M; Rawe, Vanesa Y

    2011-06-01

    The oocyte's meiotic spindle is a dynamic structure that relies on microtubule organization and regulation by centrosomes. Disorganization of centrosomal proteins, including the nuclear mitotic apparatus (NuMA) protein and the molecular motor complex dynein/dynactin, can lead to chromosomal instability and developmental abnormalities. The present study reports the distribution and function of these proteins in human oocytes, zygotes and early embryos. A total of 239 oocytes, 90 zygotes and discarded embryos were fixed and analyzed with confocal microscopy for NuMA and dynactin distribution together with microtubules and chromatin. Microtubule-associated dynein-dependent transport functions were explored by inhibiting phosphatase and ATPase activity with sodium-orthovanadate (SOV). At germinal vesicle (GV) stages, NuMA was dispersed across the nucleoplasm. After GV breaks down, NuMA became cytoplasmic before localizing at the spindle poles in metaphase I and II oocytes. Aberrant NuMA localization patterns were found during oocyte in vitro maturation. After fertilization, normal and abnormal pronuclear stage zygotes and embryos displayed translocation of NuMA to interphase nuclei. SOV treatment for up to 2 h induced lower maturation rates with chromosomal scattering and ectopic localization of NuMA. Accurate distribution of NuMA is important for oocyte maturation, zygote and embryo development in humans. Proper assembly of NuMA is likely necessary for bipolar spindle organization and human oocyte developmental competence.

  7. CYLD regulates spindle orientation by stabilizing astral microtubules and promoting dishevelled-NuMA-dynein/dynactin complex formation.

    Science.gov (United States)

    Yang, Yunfan; Liu, Min; Li, Dengwen; Ran, Jie; Gao, Jinmin; Suo, Shaojun; Sun, Shao-Cong; Zhou, Jun

    2014-02-11

    Oriented cell division is critical for cell fate specification, tissue organization, and tissue homeostasis, and relies on proper orientation of the mitotic spindle. The molecular mechanisms underlying the regulation of spindle orientation remain largely unknown. Herein, we identify a critical role for cylindromatosis (CYLD), a deubiquitinase and regulator of microtubule dynamics, in the control of spindle orientation. CYLD is highly expressed in mitosis and promotes spindle orientation by stabilizing astral microtubules and deubiquitinating the cortical polarity protein dishevelled. The deubiquitination of dishevelled enhances its interaction with nuclear mitotic apparatus, stimulating the cortical localization of nuclear mitotic apparatus and the dynein/dynactin motor complex, a requirement for generating pulling forces on astral microtubules. These findings uncover CYLD as an important player in the orientation of the mitotic spindle and cell division and have important implications in health and disease.

  8. JMJD5 (Jumonji Domain-containing 5) Associates with Spindle Microtubules and Is Required for Proper Mitosis.

    Science.gov (United States)

    He, Zhimin; Wu, Junyu; Su, Xiaonan; Zhang, Ye; Pan, Lixia; Wei, Huimin; Fang, Qiang; Li, Haitao; Wang, Da-Liang; Sun, Fang-Lin

    2016-02-26

    Precise mitotic spindle assembly is a guarantee of proper chromosome segregation during mitosis. Chromosome instability caused by disturbed mitosis is one of the major features of various types of cancer. JMJD5 has been reported to be involved in epigenetic regulation of gene expression in the nucleus, but little is known about its function in mitotic process. Here we report the unexpected localization and function of JMJD5 in mitotic progression. JMJD5 partially accumulates on mitotic spindles during mitosis, and depletion of JMJD5 results in significant mitotic arrest, spindle assembly defects, and sustained activation of the spindle assembly checkpoint (SAC). Inactivating SAC can efficiently reverse the mitotic arrest caused by JMJD5 depletion. Moreover, JMJD5 is found to interact with tubulin proteins and associate with microtubules during mitosis. JMJD5-depleted cells show a significant reduction of α-tubulin acetylation level on mitotic spindles and fail to generate enough interkinetochore tension to satisfy the SAC. Further, JMJD5 depletion also increases the susceptibility of HeLa cells to the antimicrotubule agent. Taken together, these results suggest that JMJD5 plays an important role in regulating mitotic progression, probably by modulating the stability of spindle microtubules. © 2016 by The American Society for Biochemistry and Molecular Biology, Inc.

  9. Phylogenomics-guided discovery of a novel conserved cassette of short linear motifs in bubr1 essential for the spindle checkpoint

    NARCIS (Netherlands)

    Tromer, Eelco; Bade, Debora; Snel, Berend; Kops, Geert J P L

    2016-01-01

    The spindle assembly checkpoint (SAC) maintains genomic integrity by preventing progression of mitotic cell division until all chromosomes are stably attached to spindle microtubules. The SAC critically relies on the paralogues Bub1 and BubR1/Mad3, which integrate kinetochore-spindle attachment

  10. Phylogenomics-guided discovery of a novel conserved cassette of short linear motifs in BubR1 essential for the spindle checkpoint

    NARCIS (Netherlands)

    Tromer, Eelco; Bade, Debora; Snel, Berend; Kops, Geert J P L

    2016-01-01

    The spindle assembly checkpoint (SAC) maintains genomic integrity by preventing progression of mitotic cell division until all chromosomes are stably attached to spindle microtubules. The SAC critically relies on the paralogues Bub1 and BubR1/Mad3, which integrate kinetochore-spindle attachment

  11. Cytological effects of oxytocic agents on mitotic chromosomes of ...

    African Journals Online (AJOL)

    These include disturbed prophase, spindle inhibition, star metaphase, chromatid bridge, precocious chromosome and even nuclear disintegration. The percentage of abnormal cells increased with increase in concentration of treatment drugs and duration of treatment. The possible reasons for the low mitotic index, ...

  12. The spindle assembly checkpoint: progress and persistent puzzles.

    Science.gov (United States)

    Hauf, Silke

    2013-12-01

    The spindle assembly checkpoint is a conserved mitotic signalling pathway that ensures the equal segregation of chromosomes to daughter cells. Despite intensive work in many model organisms, key features of this safety mechanism remain unexplained. In the present review, I briefly summarize advances made in the last few years, and then focus on unexplored corners of this signalling pathway.

  13. SLK-dependent activation of ERMs controls LGN-NuMA localization and spindle orientation.

    Science.gov (United States)

    Machicoane, Mickael; de Frutos, Cristina A; Fink, Jenny; Rocancourt, Murielle; Lombardi, Yannis; Garel, Sonia; Piel, Matthieu; Echard, Arnaud

    2014-06-23

    Mitotic spindle orientation relies on a complex dialog between the spindle microtubules and the cell cortex, in which F-actin has been recently implicated. Here, we report that the membrane-actin linkers ezrin/radixin/moesin (ERMs) are strongly and directly activated by the Ste20-like kinase at mitotic entry in mammalian cells. Using microfabricated adhesive substrates to control the axis of cell division, we found that the activation of ERMs plays a key role in guiding the orientation of the mitotic spindle. Accordingly, impairing ERM activation in apical progenitors of the mouse embryonic neocortex severely disturbed spindle orientation in vivo. At the molecular level, ERM activation promotes the polarized association at the mitotic cortex of leucine-glycine-asparagine repeat protein (LGN) and nuclear mitotic apparatus (NuMA) protein, two essential factors for spindle orientation. We propose that activated ERMs, together with Gαi, are critical for the correct localization of LGN-NuMA force generator complexes and hence for proper spindle orientation. © 2014 Machicoane et al.

  14. NuMA is required for proper spindle assembly and chromosome alignment in prometaphase.

    Science.gov (United States)

    Haren, Laurence; Gnadt, Nicole; Wright, Michel; Merdes, Andreas

    2009-04-28

    NuMA is a protein that has been previously shown to play a role in focusing microtubules at the mitotic spindle poles. However, most previous work relies on experimental methods that might cause dominant side effects on spindle formation, such as microinjection of antibodies, overexpression of mutant protein, or immunodepletion of NuMA-containing protein complexes. To circumvent these technical problems, we performed siRNA experiments in which we depleted the majority of NuMA in human cultured cells. Depleted mitotic cells show a prolonged duration of prometaphase, with spindle pole defects and with unattached, unaligned chromosomes. Our data confirm that NuMA is important for spindle pole formation, and for cohesion of centrosome-derived microtubules with the bulk of spindle microtubules. Our findings of NuMA-dependent defects in chromosome alignment suggest that NuMA is involved in stabilizing kinetochore fibres.

  15. Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning

    OpenAIRE

    Kojo, Kei H; Yasuhara, Hiroki; Hasezawa, Seiichiro

    2014-01-01

    Precise division plane determination is essential for plant development. At metaphase, a dense actin microfilament meshwork appears on both sides of the cell center, forming a characteristic cortical actin microfilament twin peak pattern in BY-2 cells. We previously reported a strong correlation between altered cortical actin microfilament patterning and an oblique mitotic spindle orientation, implying that these actin microfilament twin peaks play a role in the regulation of mitotic spindle ...

  16. Inhibition of clathrin by pitstop 2 activates the spindle assembly checkpoint and induces cell death in dividing HeLa cancer cells

    Directory of Open Access Journals (Sweden)

    Smith Charlotte M

    2013-01-01

    Full Text Available Abstract Background During metaphase clathrin stabilises the mitotic spindle kinetochore(K-fibres. Many anti-mitotic compounds target microtubule dynamics. Pitstop 2™ is the first small molecule inhibitor of clathrin terminal domain and inhibits clathrin-mediated endocytosis. We investigated its effects on a second function for clathrin in mitosis. Results Pitstop 2 did not impair clathrin recruitment to the spindle but disrupted its function once stationed there. Pitstop 2 trapped HeLa cells in metaphase through loss of mitotic spindle integrity and activation of the spindle assembly checkpoint, phenocopying clathrin depletion and aurora A kinase inhibition. Conclusions Pitstop 2 is therefore a new tool for investigating clathrin spindle dynamics. Pitstop 2 reduced viability in dividing HeLa cells, without affecting dividing non-cancerous NIH3T3 cells, suggesting that clathrin is a possible novel anti-mitotic drug target.

  17. APC/C-Cdh1-dependent anaphase and telophase progression during mitotic slippage

    Directory of Open Access Journals (Sweden)

    Toda Kazuhiro

    2012-02-01

    Full Text Available Abstract Background The spindle assembly checkpoint (SAC inhibits anaphase progression in the presence of insufficient kinetochore-microtubule attachments, but cells can eventually override mitotic arrest by a process known as mitotic slippage or adaptation. This is a problem for cancer chemotherapy using microtubule poisons. Results Here we describe mitotic slippage in yeast bub2Δ mutant cells that are defective in the repression of precocious telophase onset (mitotic exit. Precocious activation of anaphase promoting complex/cyclosome (APC/C-Cdh1 caused mitotic slippage in the presence of nocodazole, while the SAC was still active. APC/C-Cdh1, but not APC/C-Cdc20, triggered anaphase progression (securin degradation, separase-mediated cohesin cleavage, sister-chromatid separation and chromosome missegregation, in addition to telophase onset (mitotic exit, during mitotic slippage. This demonstrates that an inhibitory system not only of APC/C-Cdc20 but also of APC/C-Cdh1 is critical for accurate chromosome segregation in the presence of insufficient kinetochore-microtubule attachments. Conclusions The sequential activation of APC/C-Cdc20 to APC/C-Cdh1 during mitosis is central to accurate mitosis. Precocious activation of APC/C-Cdh1 in metaphase (pre-anaphase causes mitotic slippage in SAC-activated cells. For the prevention of mitotic slippage, concomitant inhibition of APC/C-Cdh1 may be effective for tumor therapy with mitotic spindle poisons in humans.

  18. Carbamazepine induces mitotic arrest in mammalian Vero cells

    International Nuclear Information System (INIS)

    Perez Martin, J.M.; Fernandez Freire, P.; Labrador, V.; Hazen, M.J.

    2008-01-01

    We reported recently that the anticonvulsant drug carbamazepine, at supratherapeutic concentrations, exerts antiproliferative effects in mammalian Vero cells, but the underlying mechanism has not been elucidated. This motivates us to examine rigorously whether growth arrest was associated with structural changes in cellular organization during mitosis. In the present work, we found that exposure of the cells to carbamazepine led to an increase in mitotic index, mainly due to the sustained block at the metaphase/anaphase boundary, with the consequent inhibition of cell proliferation. Indirect immunofluorescence, using antibodies directed against spindle apparatus proteins, revealed that mitotic arrest was associated with formation of monopolar spindles, caused by impairment of centrosome separation. The final consequence of the spindle defects induced by carbamazepine, depended on the duration of cell cycle arrest. Following the time course of accumulation of metaphase and apoptotic cells during carbamazepine treatments, we observed a causative relationship between mitotic arrest and induction of cell death. Conversely, cells released from the block of metaphase by removal of the drug, continued to progress through mitosis and resume normal proliferation. Our results show that carbamazepine shares a common antiproliferative mechanism with spindle-targeted drugs and contribute to a better understanding of the cytostatic activity previously described in Vero cells. Additional studies are in progress to extend these initial findings that define a novel mode of action of carbamazepine in cultured mammalian cells

  19. Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA)

    International Nuclear Information System (INIS)

    Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa; Yoon, Hyun-Joo; Yoo, Hae Yong; Choi, Cheol Yong

    2014-01-01

    Highlights: •NuMA is modified by SUMO-1 in a cell cycle-dependent manner. •NuMA lysine 1766 is the primary target site for SUMOylation. •SUMOylation-deficient NuMA induces multiple spindle poles during mitosis. •SUMOylated NuMA induces microtubule bundling. -- Abstract: Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis

  20. Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA)

    Energy Technology Data Exchange (ETDEWEB)

    Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa [Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yoon, Hyun-Joo [TissueGene Inc. 9605 Medical Center Dr., Rockville, MD 20850 (United States); Yoo, Hae Yong [Department of Health Sciences and Technology, Samsung Advanced Institute for Health Sciences and Technology, Samsung Medical Center, Sungkyunkwan University, Seoul 135-710 (Korea, Republic of); Choi, Cheol Yong, E-mail: choicy@skku.ac.kr [Department of Biological Sciences, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2014-01-03

    Highlights: •NuMA is modified by SUMO-1 in a cell cycle-dependent manner. •NuMA lysine 1766 is the primary target site for SUMOylation. •SUMOylation-deficient NuMA induces multiple spindle poles during mitosis. •SUMOylated NuMA induces microtubule bundling. -- Abstract: Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis.

  1. NUP98 fusion oncoproteins interact with the APC/CCdc20 as a pseudosubstrate and prevent mitotic checkpoint complex binding

    OpenAIRE

    Salsi, Valentina; Fantini, Sebastian; Zappavigna, Vincenzo

    2016-01-01

    NUP98 is a recurrent partner gene in translocations causing acute myeloid leukemias and myelodisplastic syndrome. The expression of NUP98 fusion oncoproteins has been shown to induce mitotic spindle defects and chromosome missegregation, which correlate with the capability of NUP98 fusions to cause mitotic checkpoint attenuation. We show that NUP98 oncoproteins physically interact with the APC/CCdc20 in the absence of the NUP98 partner protein RAE1, and prevent the binding of the mitotic chec...

  2. NuMA phosphorylation by CDK1 couples mitotic progression with cortical dynein function.

    Science.gov (United States)

    Kotak, Sachin; Busso, Coralie; Gönczy, Pierre

    2013-09-11

    Spindle positioning and spindle elongation are critical for proper cell division. In human cells, an evolutionary conserved ternary complex (NuMA/LGN/Gαi) anchors dynein at the cortex during metaphase, thus ensuring correct spindle positioning. Whether this complex contributes to anaphase spindle elongation is not known. More generally, the mechanisms coupling mitotic progression with spindle behaviour remain elusive. Here, we uncover that levels of cortical dynein markedly increase during anaphase in a NuMA-dependent manner. We demonstrate that during metaphase, CDK1-mediated phosphorylation at T2055 negatively regulates NuMA cortical localization and that this phosphorylation is counteracted by PPP2CA phosphatase activity. We establish that this tug of war is essential for proper levels of cortical dynein and thus spindle positioning during metaphase. Moreover, we find that upon CDK1 inactivation in anaphase, the rise in dephosphorylated NuMA at the cell cortex leads to cortical dynein enrichment, and thus to robust spindle elongation. Our findings uncover a mechanism whereby the status of NuMA phosphorylation coordinates mitotic progression with proper spindle function.

  3. Mitotic chromosome condensation in vertebrates

    Energy Technology Data Exchange (ETDEWEB)

    Vagnarelli, Paola, E-mail: P.Vagnarelli@ed.ac.uk

    2012-07-15

    Work from several laboratories over the past 10-15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292-301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories-a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307-316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119-1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579-589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different classes

  4. Mitotic chromosome condensation in vertebrates

    International Nuclear Information System (INIS)

    Vagnarelli, Paola

    2012-01-01

    Work from several laboratories over the past 10–15 years has revealed that, within the interphase nucleus, chromosomes are organized into spatially distinct territories [T. Cremer, C. Cremer, Chromosome territories, nuclear architecture and gene regulation in mammalian cells, Nat. Rev. Genet. 2 (2001) 292–301 and T. Cremer, M. Cremer, S. Dietzel, S. Muller, I. Solovei, S. Fakan, Chromosome territories—a functional nuclear landscape, Curr. Opin. Cell Biol. 18 (2006) 307–316]. The overall compaction level and intranuclear location varies as a function of gene density for both entire chromosomes [J.A. Croft, J.M. Bridger, S. Boyle, P. Perry, P. Teague,W.A. Bickmore, Differences in the localization and morphology of chromosomes in the human nucleus, J. Cell Biol. 145 (1999) 1119–1131] and specific chromosomal regions [N.L. Mahy, P.E. Perry, S. Gilchrist, R.A. Baldock, W.A. Bickmore, Spatial organization of active and inactive genes and noncoding DNA within chromosome territories, J. Cell Biol. 157 (2002) 579–589] (Fig. 1A, A'). In prophase, when cyclin B activity reaches a high threshold, chromosome condensation occurs followed by Nuclear Envelope Breakdown (NEB) [1]. At this point vertebrate chromosomes appear as compact structures harboring an attachment point for the spindle microtubules physically recognizable as a primary constriction where the two sister chromatids are held together. The transition from an unshaped interphase chromosome to the highly structured mitotic chromosome (compare Figs. 1A and B) has fascinated researchers for several decades now; however a definite picture of how this process is achieved and regulated is not yet in our hands and it will require more investigation to comprehend the complete process. From a biochemical point of view a vertebrate mitotic chromosomes is composed of DNA, histone proteins (60%) and non-histone proteins (40%) [6]. I will discuss below what is known to date on the contribution of these two different

  5. When the genome plays dice: circumvention of the spindle assembly checkpoint and near-random chromosome segregation in multipolar cancer cell mitoses.

    Directory of Open Access Journals (Sweden)

    David Gisselsson

    Full Text Available BACKGROUND: Normal cell division is coordinated by a bipolar mitotic spindle, ensuring symmetrical segregation of chromosomes. Cancer cells, however, occasionally divide into three or more directions. Such multipolar mitoses have been proposed to generate genetic diversity and thereby contribute to clonal evolution. However, this notion has been little validated experimentally. PRINCIPAL FINDINGS: Chromosome segregation and DNA content in daughter cells from multipolar mitoses were assessed by multiphoton cross sectioning and fluorescence in situ hybridization in cancer cells and non-neoplastic transformed cells. The DNA distribution resulting from multipolar cell division was found to be highly variable, with frequent nullisomies in the daughter cells. Time-lapse imaging of H2B/GFP-labelled multipolar mitoses revealed that the time from the initiation of metaphase to the beginning of anaphase was prolonged and that the metaphase plates often switched polarity several times before metaphase-anaphase transition. The multipolar metaphase-anaphase transition was accompanied by a normal reduction of cellular cyclin B levels, but typically occurred before completion of the normal separase activity cycle. Centromeric AURKB and MAD2 foci were observed frequently to remain on the centromeres of multipolar ana-telophase chromosomes, indicating that multipolar mitoses were able to circumvent the spindle assembly checkpoint with some sister chromatids remaining unseparated after anaphase. Accordingly, scoring the distribution of individual chromosomes in multipolar daughter nuclei revealed a high frequency of nondisjunction events, resulting in a near-binomial allotment of sister chromatids to the daughter cells. CONCLUSION: The capability of multipolar mitoses to circumvent the spindle assembly checkpoint system typically results in a near-random distribution of chromosomes to daughter cells. Spindle multipolarity could thus be a highly efficient

  6. When the genome plays dice: circumvention of the spindle assembly checkpoint and near-random chromosome segregation in multipolar cancer cell mitoses.

    Science.gov (United States)

    Gisselsson, David; Håkanson, Ulf; Stoller, Patrick; Marti, Dominik; Jin, Yuesheng; Rosengren, Anders H; Stewénius, Ylva; Kahl, Fredrik; Panagopoulos, Ioannis

    2008-04-02

    Normal cell division is coordinated by a bipolar mitotic spindle, ensuring symmetrical segregation of chromosomes. Cancer cells, however, occasionally divide into three or more directions. Such multipolar mitoses have been proposed to generate genetic diversity and thereby contribute to clonal evolution. However, this notion has been little validated experimentally. Chromosome segregation and DNA content in daughter cells from multipolar mitoses were assessed by multiphoton cross sectioning and fluorescence in situ hybridization in cancer cells and non-neoplastic transformed cells. The DNA distribution resulting from multipolar cell division was found to be highly variable, with frequent nullisomies in the daughter cells. Time-lapse imaging of H2B/GFP-labelled multipolar mitoses revealed that the time from the initiation of metaphase to the beginning of anaphase was prolonged and that the metaphase plates often switched polarity several times before metaphase-anaphase transition. The multipolar metaphase-anaphase transition was accompanied by a normal reduction of cellular cyclin B levels, but typically occurred before completion of the normal separase activity cycle. Centromeric AURKB and MAD2 foci were observed frequently to remain on the centromeres of multipolar ana-telophase chromosomes, indicating that multipolar mitoses were able to circumvent the spindle assembly checkpoint with some sister chromatids remaining unseparated after anaphase. Accordingly, scoring the distribution of individual chromosomes in multipolar daughter nuclei revealed a high frequency of nondisjunction events, resulting in a near-binomial allotment of sister chromatids to the daughter cells. The capability of multipolar mitoses to circumvent the spindle assembly checkpoint system typically results in a near-random distribution of chromosomes to daughter cells. Spindle multipolarity could thus be a highly efficient generator of genetically diverse minority clones in transformed cell

  7. Cell cycle-dependent SUMO-1 conjugation to nuclear mitotic apparatus protein (NuMA).

    Science.gov (United States)

    Seo, Jae Sung; Kim, Ha Na; Kim, Sun-Jick; Bang, Jiyoung; Kim, Eun-A; Sung, Ki Sa; Yoon, Hyun-Joo; Yoo, Hae Yong; Choi, Cheol Yong

    2014-01-03

    Covalent conjugation of proteins with small ubiquitin-like modifier 1 (SUMO-1) plays a critical role in a variety of cellular functions including cell cycle control, replication, and transcriptional regulation. Nuclear mitotic apparatus protein (NuMA) localizes to spindle poles during mitosis, and is an essential component in the formation and maintenance of mitotic spindle poles. Here we show that NuMA is a target for covalent conjugation to SUMO-1. We find that the lysine 1766 residue is the primary NuMA acceptor site for SUMO-1 conjugation. Interestingly, SUMO modification of endogenous NuMA occurs at the entry into mitosis and this modification is reversed after exiting from mitosis. Knockdown of Ubc9 or forced expression of SENP1 results in impairment of the localization of NuMA to mitotic spindle poles during mitosis. The SUMOylation-deficient NuMA mutant is defective in microtubule bundling, and multiple spindles are induced during mitosis. The mitosis-dependent dynamic SUMO-1 modification of NuMA might contribute to NuMA-mediated formation and maintenance of mitotic spindle poles during mitosis. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Single-walled carbon nanotube-induced mitotic disruption⋆

    OpenAIRE

    Sargent, L.M.; Hubbs, A.F.; Young, S.-H.; Kashon, M.L.; Dinu, C.Z.; Salisbury, J.L.; Benkovic, S.A.; Lowry, D.T.; Murray, A.R.; Kisin, E.R.; Siegrist, K.J.; Battelli, L.; Mastovich, J.; Sturgeon, J.L.; Bunker, K.L.

    2011-01-01

    Carbon nanotubes were among the earliest products of nanotechnology and have many potential applications in medicine, electronics, and manufacturing. The low density, small size, and biological persistence of carbon nanotubes create challenges for exposure control and monitoring and make respiratory exposures to workers likely. We have previously shown mitotic spindle aberrations in cultured primary and immortalized human airway epithelial cells exposed to 24, 48 and 96 μg/cm2 single-walled c...

  9. Cyclin B degradation leads to NuMA release from dynein/dynactin and from spindle poles.

    Science.gov (United States)

    Gehmlich, Katja; Haren, Laurence; Merdes, Andreas

    2004-01-01

    The protein NuMA localizes to mitotic spindle poles where it contributes to the organization of microtubules. In this study, we demonstrate that NuMA loses its stable association with the spindle poles after anaphase onset. Using extracts from Xenopus laevis eggs, we show that NuMA is dephosphorylated in anaphase and released from dynein and dynactin. In the presence of a nondegradable form of cyclin B (Delta90), NuMA remains phosphorylated and associated with dynein and dynactin, and remains localized to stable spindle poles that fail to disassemble at the end of mitosis. Inhibition of NuMA or dynein allows completion of mitosis, despite inducing spindle pole abnormalities. We propose that NuMA functions early in mitosis during the formation of spindle poles, but is released from the spindle after anaphase, to allow spindle disassembly and remodelling of the microtubule network.

  10. Multiple mechanisms regulate NuMA dynamics at spindle poles.

    Science.gov (United States)

    Kisurina-Evgenieva, Olga; Mack, Gary; Du, Quansheng; Macara, Ian; Khodjakov, Alexey; Compton, Duane A

    2004-12-15

    The large coiled-coil protein NuMA plays an essential role in organizing microtubule minus ends at spindle poles in vertebrate cells. Here, we use both in vivo and in vitro methods to examine NuMA dynamics at mitotic spindle poles. Using fluorescence recovery after photobleaching, we show that an exogenously expressed green-fluorescent-protein/NuMA fusion undergoes continuous exchange between soluble and spindle-associated pools in living cells. These dynamics require cellular energy and display an average half-time for fluorescence recovery of approximately 3 minutes. To explore how NuMA dynamics at spindle poles is regulated, we exploited the association of NuMA with microtubule asters formed in mammalian mitotic extracts. Using a monoclonal antibody specific for human NuMA, we followed the fate of human NuMA associated with microtubule asters upon dilution with a hamster mitotic extract. Consistent with in vivo data, this assay shows that NuMA can be displaced from the core of pre-assembled asters into the soluble pool. The half-time of NuMA displacement from asters under these conditions is approximately 5 minutes. Using this assay, we show that protein kinase activity and the NuMA-binding protein LGN regulate the dynamic exchange of NuMA on microtubule asters. Thus, the dynamic properties of NuMA are regulated by multiple mechanisms including protein phosphorylation and binding to the LGN protein, and the rate of exchange between soluble and microtubule-associated pools suggests that NuMA associates with an insoluble matrix at spindle poles.

  11. NuMA: a nuclear protein involved in mitotic centrosome function.

    Science.gov (United States)

    Zeng, C

    2000-06-01

    Nuclear mitotic apparatus protein, NuMA, is an abundant 240 kDa protein with microtubule (MT) binding capacity via its carboxyl terminal region. Structurally, it has been shown to be a double-strand coiled-coil that has a high potential to form filamentous polymers. During interphase, NuMA locates within the nucleus but rapidly redistributes to the separating centrosomes during early mitosis. Xenopus NuMA associates with MT minus end-directed motor cytoplasmic dynein and its motility-activating complex dynactin at mitotic centrosomal regions. This NuMA-motor complex binds the free ends of MTs, converging and tethering spindle MT ends to the poles. A similar scenario appears to be true in higher vertebrates as well. As a mitotic centrosomal component, NuMA is essential for the organization and stabilization of spindle poles from early mitosis until at least the onset of anaphase. The cell cycle-dependent distribution and function of NuMA is regulated by phosphorylation and dephosphorylation, and p34/CDC2 activity is important to the mitotic role of NuMA. This review summarizes data about the structural features and mitotic function of NuMA with particular emphasis on the newly discovered NuMA-motor complex in spindle organization. Furthermore, NuMA may represent a large group of proteins whose mitotic function is sequestered in the nucleus during interphase. Copyright 2000 Wiley-Liss, Inc.

  12. Timeless links replication termination to mitotic kinase activation.

    Directory of Open Access Journals (Sweden)

    Jayaraju Dheekollu

    2011-05-01

    Full Text Available The mechanisms that coordinate the termination of DNA replication with progression through mitosis are not completely understood. The human Timeless protein (Tim associates with S phase replication checkpoint proteins Claspin and Tipin, and plays an important role in maintaining replication fork stability at physical barriers, like centromeres, telomeres and ribosomal DNA repeats, as well as at termination sites. We show here that human Tim can be isolated in a complex with mitotic entry kinases CDK1, Auroras A and B, and Polo-like kinase (Plk1. Plk1 bound Tim directly and colocalized with Tim at a subset of mitotic structures in M phase. Tim depletion caused multiple mitotic defects, including the loss of sister-chromatid cohesion, loss of mitotic spindle architecture, and a failure to exit mitosis. Tim depletion caused a delay in mitotic kinase activity in vivo and in vitro, as well as a reduction in global histone H3 S10 phosphorylation during G2/M phase. Tim was also required for the recruitment of Plk1 to centromeric DNA and formation of catenated DNA structures at human centromere alpha satellite repeats. Taken together, these findings suggest that Tim coordinates mitotic kinase activation with termination of DNA replication.

  13. Spindle cell carcinoma of the conjunctiva: A rare entity

    Directory of Open Access Journals (Sweden)

    Muge Coban-Karatas

    2016-01-01

    Full Text Available An 85-year-old male presented with painless bulging lesion over the cornea. Clinical history, diagnostic imaging studies, and histopathologic sections were evaluated. The patient clinically displayed an vascularized conjunctival lesion located at the superior bulbar conjunctiva with extension onto cornea covering 2/3 of his pupillary aperture superiorly. His visual acuity was counting fingers at 4 m. The patient underwent a total excision of the lesion including conjunctival and corneal parts. Histopathologic evaluation revealed spindle cell carcinoma which involves the whole conjunctival squamous epithelium with significant polarity loss, nuclear enlargement with hyperchromasia and pleomorphism, and mitotic activity. Diagnosis of spindle cell carcinoma is challenging because of overlapping histopathological features with other spindle cell tumors. The detailed pathologic examination is very important for the decision of proper treatment.

  14. Structure of a Blinkin-BUBR1 complex reveals an interaction crucial for kinetochore-mitotic checkpoint regulation via an unanticipated binding Site

    DEFF Research Database (Denmark)

    Bolanos-Garcia, Victor M; Lischetti, Tiziana; Matak-Vinković, Dijana

    2011-01-01

    The maintenance of genomic stability relies on the spindle assembly checkpoint (SAC), which ensures accurate chromosome segregation by delaying the onset of anaphase until all chromosomes are properly bioriented and attached to the mitotic spindle. BUB1 and BUBR1 kinases are central for this proc...

  15. Cenp-meta is required for sustained spindle checkpoint

    Directory of Open Access Journals (Sweden)

    Thomas Rubin

    2014-05-01

    Full Text Available Cenp-E is a kinesin-like motor protein required for efficient end-on attachment of kinetochores to the spindle microtubules. Cenp-E immunodepletion in Xenopus mitotic extracts results in the loss of mitotic arrest and massive chromosome missegregation, whereas its depletion in mammalian cells leads to chromosome segregation defects despite the presence of a functional spindle assembly checkpoint (SAC. Cenp-meta has previously been reported to be the Drosophila homolog of vertebrate Cenp-E. In this study, we show that cenp-metaΔ mutant neuroblasts arrest in mitosis when treated with colchicine. cenp-metaΔ mutant cells display a mitotic delay. Yet, despite the persistence of the two checkpoint proteins Mad2 and BubR1 on unattached kinetochores, these cells eventually enter anaphase and give rise to highly aneuploid daughter cells. Indeed, we find that cenp-metaΔ mutant cells display a slow but continuous degradation of cyclin B, which eventually triggers the mitotic exit observed. Thus, our data provide evidence for a role of Cenp-meta in sustaining the SAC response.

  16. NuMA-microtubule interactions are critical for spindle orientation and the morphogenesis of diverse epidermal structures.

    Science.gov (United States)

    Seldin, Lindsey; Muroyama, Andrew; Lechler, Terry

    2016-01-14

    Mitotic spindle orientation is used to generate cell fate diversity and drive proper tissue morphogenesis. A complex of NuMA and dynein/dynactin is required for robust spindle orientation in a number of cell types. Previous research proposed that cortical dynein/dynactin was sufficient to generate forces on astral microtubules (MTs) to orient the spindle, with NuMA acting as a passive tether. In this study, we demonstrate that dynein/dynactin is insufficient for spindle orientation establishment in keratinocytes and that NuMA's MT-binding domain, which targets MT tips, is also required. Loss of NuMA-MT interactions in skin caused defects in spindle orientation and epidermal differentiation, leading to neonatal lethality. In addition, we show that NuMA-MT interactions are also required in adult mice for hair follicle morphogenesis and spindle orientation within the transit-amplifying cells of the matrix. Loss of spindle orientation in matrix cells results in defective differentiation of matrix-derived lineages. Our results reveal an additional and direct function of NuMA during mitotic spindle positioning, as well as a reiterative use of spindle orientation in the skin to build diverse structures.

  17. Autocatalytic microtubule nucleation determines the size and mass of Xenopus laevis egg extract spindles.

    Science.gov (United States)

    Decker, Franziska; Oriola, David; Dalton, Benjamin; Brugués, Jan

    2018-01-11

    Regulation of size and growth is a fundamental problem in biology. A prominent example is the formation of the mitotic spindle, where protein concentration gradients around chromosomes are thought to regulate spindle growth by controlling microtubule nucleation. Previous evidence suggests that microtubules nucleate throughout the spindle structure. However, the mechanisms underlying microtubule nucleation and its spatial regulation are still unclear. Here, we developed an assay based on laser ablation to directly probe microtubule nucleation events in Xenopus laevis egg extracts. Combining this method with theory and quantitative microscopy, we show that the size of a spindle is controlled by autocatalytic growth of microtubules, driven by microtubule-stimulated microtubule nucleation. The autocatalytic activity of this nucleation system is spatially regulated by the limiting amounts of active microtubule nucleators, which decrease with distance from the chromosomes. This mechanism provides an upper limit to spindle size even when resources are not limiting. © 2018, Decker et al.

  18. Noninvasive three-dimensional live imaging methodology for the spindles at meiosis and mitosis

    Science.gov (United States)

    Zheng, Jing-gao; Huo, Tiancheng; Tian, Ning; Chen, Tianyuan; Wang, Chengming; Zhang, Ning; Zhao, Fengying; Lu, Danyu; Chen, Dieyan; Ma, Wanyun; Sun, Jia-lin; Xue, Ping

    2013-05-01

    The spindle plays a crucial role in normal chromosome alignment and segregation during meiosis and mitosis. Studying spindles in living cells noninvasively is of great value in assisted reproduction technology (ART). Here, we present a novel spindle imaging methodology, full-field optical coherence tomography (FF-OCT). Without any dye labeling and fixation, we demonstrate the first successful application of FF-OCT to noninvasive three-dimensional (3-D) live imaging of the meiotic spindles within the mouse living oocytes at metaphase II as well as the mitotic spindles in the living zygotes at metaphase and telophase. By post-processing of the 3-D dataset obtained with FF-OCT, the important morphological and spatial parameters of the spindles, such as short and long axes, spatial localization, and the angle of meiotic spindle deviation from the first polar body in the oocyte were precisely measured with the spatial resolution of 0.7 μm. Our results reveal the potential of FF-OCT as an imaging tool capable of noninvasive 3-D live morphological analysis for spindles, which might be useful to ART related procedures and many other spindle related studies.

  19. Mitotic slippage and the subsequent cell fates after inhibition of Aurora B during tubulin-binding agent-induced mitotic arrest.

    Science.gov (United States)

    Tsuda, Yasuo; Iimori, Makoto; Nakashima, Yuichiro; Nakanishi, Ryota; Ando, Koji; Ohgaki, Kippei; Kitao, Hiroyuki; Saeki, Hiroshi; Oki, Eiji; Maehara, Yoshihiko

    2017-12-01

    Tubulin-binding agents (TBAs) are designed to target microtubule (MT) dynamics, resulting in compromised mitotic spindles and an unsatisfied spindle assembly checkpoint. The activity of Aurora B kinase is indispensable for TBA-induced mitotic arrest, and its inhibition causes mitotic slippage and postmitotic endoreduplication. However, the precise phenomenon underlying mitotic slippage, which is caused by treatment with both Aurora B inhibitors and TBAs, and the cell fate after postmitotic slippage are not completely understood. Here, we found that HeLa and breast cancer cells treated with the different types of TBAs, such as paclitaxel and eribulin (MT-stabilizing and MT-destabilizing agents, respectively), exhibited distinct behaviors of mitotic slippage on inhibition of Aurora B. In such conditions, the cell fates after postmitotic slippage vastly differed with respect to cell morphology, cell proliferation, and cytotoxicity in short-term culture; that is, the effects of inhibition of Aurora B were beneficial for cytotoxicity enhancement in eribulin treatment but not in paclitaxel. However, in long-term culture, the cells that survived after mitotic slippage underwent endoreduplication and became giant cells in both cases, resulting in cellular senescence. We propose that MT-destabilizing agents may be more appropriate than MT-stabilizing agents for treating cancer cells with a weakened Aurora B kinase activity.

  20. A SUMOylation Motif in Aurora-A: Implications in Spindle Dynamics and Oncogenesis

    Directory of Open Access Journals (Sweden)

    Ignacio ePérez de Castro

    2011-12-01

    Full Text Available Aurora-A is a serine/threonine kinase that plays critical roles in centrosome maturation, spindle dynamics and chromosome orientation and is frequently found overexpressed in human cancers. In this work, we show that Aurora-A interacts with the SUMO conjugating enzyme UBC9 and co-localizes with SUMO-1 in mitotic cells. Aurora-A can be SUMOylated in vitro and mutation in the highly conserved SUMOylation residue lysine 249 results in the induction of mitotic defects characterized by defective and multipolar spindles. The Aurora-AK249R mutant has normal kinase activity but it displays altered dynamics at the mitotic spindle. In addition, ectopic expression of the Aurora-AK249R mutant results in a significant increase in the susceptibility to malignant transformation induced by the Ras oncogene and an increased protection against apoptosis in tumor cells treated with mitotic poisons. These data suggest that modification by SUMO residues may control Aurora-A function at the spindle and suggest that deficient SUMOylation of this kinase may have relevant implications in tumor development or cancer therapy.

  1. Interaction between RB protein and NuMA is required for proper alignment of spindle microtubules.

    Science.gov (United States)

    Uchida, Chiharu; Hattori, Takayuki; Takahashi, Hirotaka; Yamamoto, Naoki; Kitagawa, Masatoshi; Taya, Yoichi

    2014-02-01

    Retinoblastoma protein (pRB) controls cell cycle progression and cell cycle exit through interactions with cellular proteins. Many pRB-binding proteins, which function in gene transcription or modulation of chromatin structure, harbor LXCXE motifs in their binding domain for pRB. In this study, we found that nuclear mitotic apparatus protein (NuMA), a mitotic spindle organizer, interacts with pRB through LSCEE sequences located in its C-terminal region. siRNA-mediated down-regulation of pRB caused aberrant distribution of NuMA and alignment of spindle microtubules in mitotic cells. Abnormal organization of spindle microtubules was also accompanied by misalignment of an over-expressed NuMA mutant (mut-NuMA) with a defect in pRB binding caused by an LSGEK mutation. The mut-NuMA-over-expressing cells showed lower potency for survival than wild-type NuMA (wt-NuMA)-over-expressing cells during 2 weeks of culture. Interestingly, knockdown of pRB reduced the population of wt-NuMA-over-expressing cells to the same level as mut-NuMA cells after 2 weeks. Taken together, pRB may have a novel function in regulating the mitotic function of NuMA and spindle organization, which are required for proper cell cycle progression. © 2013 The Authors Genes to Cells © 2013 by the Molecular Biology Society of Japan and Wiley Publishing Asia Pty Ltd.

  2. Spindle orientation bias in gut epithelial stem cell compartments is lost in precancerous tissue

    NARCIS (Netherlands)

    Quyn, A.J.; Appleton, P.L.; Carey, F.A.; Steele, R.J.; Barker, N.; Clevers, H.; Ridgway, R.A.; Sansom, O.J.; Nathke, I.S.

    2010-01-01

    The importance of asymmetric divisions for stem cell function and maintenance is well established in the developing nervous system and the skin; however, its role in gut epithelium and its importance for tumorigenesis is still debated. We demonstrate alignment of mitotic spindles perpendicular to

  3. Regulation of cell cycle by the anaphase spindle midzone

    Directory of Open Access Journals (Sweden)

    Sluder Greenfield

    2004-12-01

    Full Text Available Abstract Background A number of proteins accumulate in the spindle midzone and midbody of dividing animal cells. Besides proteins essential for cytokinesis, there are also components essential for interphase functions, suggesting that the spindle midzone and/or midbody may play a role in regulating the following cell cycle. Results We microsurgically severed NRK epithelial cells during anaphase or telophase, such that the spindle midzone/midbody was associated with only one of the daughter cells. Time-lapse recording of cells severed during early anaphase indicated that the cell with midzone underwent cytokinesis-like cortical contractions and progressed normally through the interphase, whereas the cell without midzone showed no cortical contraction and an arrest or substantial delay in the progression of interphase. Similar microsurgery during telophase showed a normal progression of interphase for both daughter cells with or without the midbody. Microsurgery of anaphase cells treated with cytochalasin D or nocodazole indicated that interphase progression was independent of cortical ingression but dependent on microtubules. Conclusions We conclude that the mitotic spindle is involved in not only the separation of chromosomes but also the regulation of cell cycle. The process may involve activation of components in the spindle midzone that are required for the cell cycle, and/or degradation of components that are required for cytokinesis but may interfere with the cell cycle.

  4. The Drosophila NuMA Homolog Mud regulates spindle orientation in asymmetric cell division.

    Science.gov (United States)

    Bowman, Sarah K; Neumüller, Ralph A; Novatchkova, Maria; Du, Quansheng; Knoblich, Juergen A

    2006-06-01

    During asymmetric cell division, the mitotic spindle must be properly oriented to ensure the asymmetric segregation of cell fate determinants into only one of the two daughter cells. In Drosophila neuroblasts, spindle orientation requires heterotrimeric G proteins and the G alpha binding partner Pins, but how the Pins-G alphai complex interacts with the mitotic spindle is unclear. Here, we show that Pins binds directly to the microtubule binding protein Mud, the Drosophila homolog of NuMA. Like NuMA, Mud can bind to microtubules and enhance microtubule polymerization. In the absence of Mud, mitotic spindles in Drosophila neuroblasts fail to align with the polarity axis. This can lead to symmetric segregation of the cell fate determinants Brat and Prospero, resulting in the mis-specification of daughter cell fates and tumor-like over proliferation in the Drosophila nervous system. Our data suggest a model in which asymmetrically localized Pins-G alphai complexes regulate spindle orientation by directly binding to Mud.

  5. Antiproliferative Fate of the Tetraploid Formed after Mitotic Slippage and Its Promotion; A Novel Target for Cancer Therapy Based on Microtubule Poisons.

    Science.gov (United States)

    Nakayama, Yuji; Inoue, Toshiaki

    2016-05-19

    Microtubule poisons inhibit spindle function, leading to activation of spindle assembly checkpoint (SAC) and mitotic arrest. Cell death occurring in prolonged mitosis is the first target of microtubule poisons in cancer therapies. However, even in the presence of microtubule poisons, SAC and mitotic arrest are not permanent, and the surviving cells exit the mitosis without cytokinesis (mitotic slippage), becoming tetraploid. Another target of microtubule poisons-based cancer therapy is antiproliferative fate after mitotic slippage. The ultimate goal of both the microtubule poisons-based cancer therapies involves the induction of a mechanism defined as mitotic catastrophe, which is a bona fide intrinsic oncosuppressive mechanism that senses mitotic failure and responds by driving a cell to an irreversible antiproliferative fate of death or senescence. This mechanism of antiproliferative fate after mitotic slippage is not as well understood. We provide an overview of mitotic catastrophe, and explain new insights underscoring a causal association between basal autophagy levels and antiproliferative fate after mitotic slippage, and propose possible improved strategies. Additionally, we discuss nuclear alterations characterizing the mitotic catastrophe (micronuclei, multinuclei) after mitotic slippage, and a possible new type of nuclear alteration (clustered micronuclei).

  6. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the P...

  7. BRCA1 interaction of centrosomal protein Nlp is required for successful mitotic progression.

    Science.gov (United States)

    Jin, Shunqian; Gao, Hua; Mazzacurati, Lucia; Wang, Yang; Fan, Wenhong; Chen, Qiang; Yu, Wei; Wang, Mingrong; Zhu, Xueliang; Zhang, Chuanmao; Zhan, Qimin

    2009-08-21

    Breast cancer susceptibility gene BRCA1 is implicated in the control of mitotic progression, although the underlying mechanism(s) remains to be further defined. Deficiency of BRCA1 function leads to disrupted mitotic machinery and genomic instability. Here, we show that BRCA1 physically interacts and colocalizes with Nlp, an important molecule involved in centrosome maturation and spindle formation. Interestingly, Nlp centrosomal localization and its protein stability are regulated by normal cellular BRCA1 function because cells containing BRCA1 mutations or silenced for endogenous BRCA1 exhibit disrupted Nlp colocalization to centrosomes and enhanced Nlp degradation. Its is likely that the BRCA1 regulation of Nlp stability involves Plk1 suppression. Inhibition of endogenous Nlp via the small interfering RNA approach results in aberrant spindle formation, aborted chromosomal segregation, and aneuploidy, which mimic the phenotypes of disrupted BRCA1. Thus, BRCA1 interaction of Nlp might be required for the successful mitotic progression, and abnormalities of Nlp lead to genomic instability.

  8. PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma.

    Science.gov (United States)

    Restall, Ian J; Parolin, Doris A E; Daneshmand, Manijeh; Hanson, Jennifer E L; Simard, Manon A; Fitzpatrick, Megan E; Kumar, Ritesh; Lavictoire, Sylvie J; Lorimer, Ian A J

    2015-01-01

    Cellular senescence is a tumor suppressor mechanism where cells enter a permanent growth arrest following cellular stress. Oncogene-induced senescence (OIS) is induced in non-malignant cells following the expression of an oncogene or inactivation of a tumor suppressor. Previously, we have shown that protein kinase C iota (PKCι) depletion induces cellular senescence in glioblastoma cells in the absence of a detectable DNA damage response. Here we demonstrate that senescent glioblastoma cells exhibit an aberrant centrosome morphology. This was observed in basal levels of senescence, in p21-induced senescence, and in PKCι depletion-induced senescence. In addition, senescent glioblastoma cells are polyploid, Ki-67 negative and arrest at the G1/S checkpoint, as determined by expression of cell cycle regulatory proteins. These markers are all consistent with cells that have undergone mitotic slippage. Failure of the spindle assembly checkpoint to function properly can lead to mitotic slippage, resulting in the premature exit of mitotic cells into the G1 phase of the cell cycle. Although in G1, these cells have the replicated DNA and centrosomal phenotype of a cell that has entered mitosis and failed to divide. Overall, we demonstrate that PKCι depletion initiates mitotic slippage-induced senescence in glioblastoma cells. To our knowledge, this is the first evidence of markers of mitotic slippage directly in senescent cells by co-staining for senescence-associated β-galactosidase and immunofluorescence markers in the same cell population. We suggest that markers of mitotic slippage be assessed in future studies of senescence to determine the extent of mitotic slippage in the induction of cellular senescence.

  9. Mcl-1 dynamics influence mitotic slippage and death in mitosis.

    Science.gov (United States)

    Sloss, Olivia; Topham, Caroline; Diez, Maria; Taylor, Stephen

    2016-02-02

    Microtubule-binding drugs such as taxol are frontline treatments for a variety of cancers but exactly how they yield patient benefit is unclear. In cell culture, inhibiting microtubule dynamics prevents spindle assembly, leading to mitotic arrest followed by either apoptosis in mitosis or slippage, whereby a cell returns to interphase without dividing. Myeloid cell leukaemia-1 (Mcl-1), a pro-survival member of the Bcl-2 family central to the intrinsic apoptosis pathway, is degraded during a prolonged mitotic arrest and may therefore act as a mitotic death timer. Consistently, we show that blocking proteasome-mediated degradation inhibits taxol-induced mitotic apoptosis in a Mcl-1-dependent manner. However, this degradation does not require the activity of either APC/C-Cdc20, FBW7 or MULE, three separate E3 ubiquitin ligases implicated in targeting Mcl-1 for degradation. This therefore challenges the notion that Mcl-1 undergoes regulated degradation during mitosis. We also show that Mcl-1 is continuously synthesized during mitosis and that blocking protein synthesis accelerates taxol induced death-in-mitosis. Modulating Mcl-1 levels also influences slippage; overexpressing Mcl-1 extends the time from mitotic entry to mitotic exit in the presence of taxol, while inhibiting Mcl-1 accelerates it. We suggest that Mcl-1 competes with Cyclin B1 for binding to components of the proteolysis machinery, thereby slowing down the slow degradation of Cyclin B1 responsible for slippage. Thus, modulating Mcl-1 dynamics influences both death-in-mitosis and slippage. However, because mitotic degradation of Mcl-1 appears not to be under the control of an E3 ligase, we suggest that the notion of network crosstalk is used with caution.

  10. Integrin-linked kinase regulates interphase and mitotic microtubule dynamics.

    Directory of Open Access Journals (Sweden)

    Simin Lim

    Full Text Available Integrin-linked kinase (ILK localizes to both focal adhesions and centrosomes in distinct multiprotein complexes. Its dual function as a kinase and scaffolding protein has been well characterized at focal adhesions, where it regulates integrin-mediated cell adhesion, spreading, migration and signaling. At the centrosomes, ILK regulates mitotic spindle organization and centrosome clustering. Our previous study showed various spindle defects after ILK knockdown or inhibition that suggested alteration in microtubule dynamics. Since ILK expression is frequently elevated in many cancer types, we investigated the effects of ILK overexpression on microtubule dynamics. We show here that overexpressing ILK in HeLa cells was associated with a shorter duration of mitosis and decreased sensitivity to paclitaxel, a chemotherapeutic agent that suppresses microtubule dynamics. Measurement of interphase microtubule dynamics revealed that ILK overexpression favored microtubule depolymerization, suggesting that microtubule destabilization could be the mechanism behind the decreased sensitivity to paclitaxel, which is known to stabilize microtubules. Conversely, the use of a small molecule inhibitor selective against ILK, QLT-0267, resulted in suppressed microtubule dynamics, demonstrating a new mechanism of action for this compound. We further show that treatment of HeLa cells with QLT-0267 resulted in higher inter-centromere tension in aligned chromosomes during mitosis, slower microtubule regrowth after cold depolymerization and the presence of a more stable population of spindle microtubules. These results demonstrate that ILK regulates microtubule dynamics in both interphase and mitotic cells.

  11. Clathrin is spindle-associated but not essential for mitosis.

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    Joana Borlido

    Full Text Available Clathrin is a multimeric protein involved in vesicle coat assembly. Recently clathrin distribution was reported to change during the cell cycle and was found to associate with the mitotic spindle. Here we test whether the recruitment of clathrin to the spindle is indicative of a critical functional contribution to mitosis.Previously a chicken pre-B lymphoma cell line (DKO-R was developed in which the endogenous clathrin heavy chain alleles were replaced with the human clathrin heavy chain under the control of a tetracycline-regulatable promoter. Receptor-mediated and fluid-phase endocytosis were significantly inhibited in this line following clathrin knockout, and we used this to explore the significance of clathrin heavy chain expression for cell cycle progression. We confirmed using confocal microscopy that clathrin colocalised with tubulin at mitotic spindles. Using a propidium iodide flow cytometric assay we found no statistical difference in the cell cycle distribution of the knockout cells versus the wild-type. Additionally, we showed that the ploidy and the recovery kinetics following cell cycle arrest with nocodazole were unchanged by repressing clathrin heavy chain expression.We conclude that the association of clathrin with the mitotic spindle and the contribution of clathrin to endocytosis are evolutionarily conserved. However we find that the contribution of clathrin to mitosis is less robust and dependent on cellular context. In other cell-lines silencing RNA has been used by others to knockdown clathrin expression resulting in an increase in the mitotic index of the cells. We show an effect on the G2/M phase population of clathrin knockdown in HEK293 cells but show that repressing clathrin expression in the DKO-R cell-line has no effect on the size of this population. Consequently this work highlights the need for a more detailed molecular understanding of the recruitment and function of clathrin at the spindle, since the

  12. Establishment and mitotic characterization of new Drosophila acentriolar cell lines from DSas-4 mutant

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    Nicolas Lecland

    2013-01-01

    In animal cells the centrosome is commonly viewed as the main cellular structure driving microtubule (MT assembly into the mitotic spindle apparatus. However, additional pathways, such as those mediated by chromatin and augmin, are involved in the establishment of functional spindles. The molecular mechanisms involved in these pathways remain poorly understood, mostly due to limitations inherent to current experimental systems available. To overcome these limitations we have developed six new Drosophila cell lines derived from Drosophila homozygous mutants for DSas-4, a protein essential for centriole biogenesis. These cells lack detectable centrosomal structures, astral MT, with dispersed pericentriolar proteins D-PLP, Centrosomin and γ-tubulin. They show poorly focused spindle poles that reach the plasma membrane. Despite being compromised for functional centrosome, these cells could successfully undergo mitosis. Live-cell imaging analysis of acentriolar spindle assembly revealed that nascent MTs are nucleated from multiple points in the vicinity of chromosomes. These nascent MTs then grow away from kinetochores allowing the expansion of fibers that will be part of the future acentriolar spindle. MT repolymerization assays illustrate that acentriolar spindle assembly occurs “inside-out” from the chromosomes. Colchicine-mediated depolymerization of MTs further revealed the presence of a functional Spindle Assembly Checkpoint (SAC in the acentriolar cells. Finally, pilot RNAi experiments open the potential use of these cell lines for the molecular dissection of anastral pathways in spindle and centrosome assembly.

  13. Reverse engineering of the spindle assembly checkpoint.

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    Andreas Doncic

    Full Text Available The Spindle Assembly Checkpoint (SAC is an intracellular mechanism that ensures proper chromosome segregation. By inhibiting Cdc20, a co-factor of the Anaphase Promoting Complex (APC, the checkpoint arrests the cell cycle until all chromosomes are properly attached to the mitotic spindle. Inhibition of Cdc20 is mediated by a conserved network of interacting proteins. The individual functions of these proteins are well characterized, but understanding of their integrated function is still rudimentary. We here describe our attempts to reverse-engineer the SAC network based on gene deletion phenotypes. We begun by formulating a general model of the SAC which enables us to predict the rate of chromosomal missegregation for any putative set of interactions between the SAC proteins. Next the missegregation rates of seven yeast strains are measured in response to the deletion of one or two checkpoint proteins. Finally, we searched for the set of interactions that correctly predicted the observed missegregation rates of all deletion mutants. Remarkably, although based on only seven phenotypes, the consistent network we obtained successfully reproduces many of the known properties of the SAC. Further insights provided by our analysis are discussed.

  14. Spindle and kinetochore associated complex subunit 1 regulates the proliferation of oral adenosquamous carcinoma CAL-27 cells in vitro

    OpenAIRE

    Zhang, Bin; Li, Ke Yi; Chen, Hai Ying; Pan, Shao Dong; Jiang, Li Cheng; Wu, Ya Ping; Liu, Shu Wei

    2013-01-01

    Background The prognosis of oral squamous cell carcinoma is very poor due to local recurrence and metastasis. This study explores the molecular events involved in oral carcinoma with the goal of developing novel therapeutic strategies. The mitotic spindle is a complex mechanical apparatus required for the accurate segregation of sister chromosomes during mitosis. Spindle and kinetochore associated complex subunit 1 (SKA1) is a microtubule-binding subcomplex of the outer kinetochore that is es...

  15. The Spindle Assembly Checkpoint Is Not Essential for Viability of Human Cells with Genetically Lowered APC/C Activity

    DEFF Research Database (Denmark)

    Wild, Thomas; Larsen, Marie Sofie Yoo; Narita, Takeo

    2016-01-01

    The anaphase-promoting complex/cyclosome (APC/C) and the spindle assembly checkpoint (SAC), which inhibits the APC/C, are essential determinants of mitotic timing and faithful division of genetic material. Activation of the APC/C is known to depend on two APC/C-interacting E2 ubiquitin-conjugatin......The anaphase-promoting complex/cyclosome (APC/C) and the spindle assembly checkpoint (SAC), which inhibits the APC/C, are essential determinants of mitotic timing and faithful division of genetic material. Activation of the APC/C is known to depend on two APC/C-interacting E2 ubiquitin...

  16. Mitotic bookmarking by transcription factors.

    Science.gov (United States)

    Kadauke, Stephan; Blobel, Gerd A

    2013-04-02

    Mitosis is accompanied by dramatic changes in chromatin organization and nuclear architecture. Transcription halts globally and most sequence-specific transcription factors and co-factors are ejected from mitotic chromatin. How then does the cell maintain its transcriptional identity throughout the cell division cycle? It has become clear that not all traces of active transcription and gene repression are erased within mitotic chromatin. Many histone modifications are stable or only partially diminished throughout mitosis. In addition, some sequence-specific DNA binding factors have emerged that remain bound to select sites within mitotic chromatin, raising the possibility that they function to transmit regulatory information through the transcriptionally silent mitotic phase, a concept that has been termed "mitotic bookmarking." Here we review recent approaches to studying potential bookmarking factors with regards to their mitotic partitioning, and summarize emerging ideas concerning the in vivo functions of mitotically bound nuclear factors.

  17. PLK1 regulates spindle formation kinetics and APC/C activation in mouse zygote.

    Science.gov (United States)

    Baran, Vladimir; Brzakova, Adela; Rehak, Pavol; Kovarikova, Veronika; Solc, Petr

    2016-06-01

    Polo-like kinase 1 (PLK1) is involved in essential events of cell cycle including mitosis in which it participates in centrosomal microtubule nucleation, spindle bipolarity establishment and cytokinesis. Although PLK1 function has been studied in cycling cancer cells, only limited data are known about its role in the first mitosis of mammalian zygotes. During the 1-cell stage of mouse embryo development, the acentriolar spindle is formed and the shift from acentriolar to centrosomal spindle formation progresses gradually throughout the preimplantation stage, thus providing a unique possibility to study acentriolar spindle formation. We have shown previously that PLK1 activity is not essential for entry into first mitosis, but is required for correct spindle formation and anaphase onset in 1-cell mouse embryos. In the present study, we extend this knowledge by employing quantitative confocal live cell imaging to determine spindle formation kinetics in the absence of PLK1 activity and answer the question whether metaphase arrest at PLK1-inhibited embryos is associated with low anaphase-promoting complex/cyclosome (APC/C) activity and consequently high securin level. We have shown that inhibition of PLK1 activity induces a delay in onset of acentriolar spindle formation during first mitosis. Although these PLK1-inhibited 1-cell embryos were finally able to form a bipolar spindle, not all chromosomes were aligned at the metaphase equator. PLK1-inhibited embryos were arrested in metaphase without any sign of APC/C activation with high securin levels. Our results document that PLK1 controls the onset of spindle assembly and spindle formation, and is essential for APC/C activation before anaphase onset in mouse zygotes.

  18. Aurora A's functions during mitotic exit: the Guess Who game

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    David eReboutier

    2015-12-01

    Full Text Available Until recently, the knowledge of Aurora A kinase functions during mitosis was limited to pre-metaphase events, particularly centrosome maturation, G2/M transition, and mitotic spindle assembly. However, an involvement of Aurora A in post-metaphase events was also suspected, but not clearly demonstrated due to the technical difficulty to perform the appropriate experiments. Recent developments of both an analog specific version of Aurora A, and of small molecule inhibitors have led to the first demonstration that Aurora A is required for the early steps of cytokinesis. As in pre-metaphase, Aurora A plays diverse functions during anaphase, essentially participating in astral microtubules dynamics and central spindle assembly and functioning. The present review describes the experimental systems used to decipher new functions of Aurora A during late mitosis and situate these functions into the context of cytokinesis mechanisms.

  19. Involvement of CNOT3 in mitotic progression through inhibition of MAD1 expression

    International Nuclear Information System (INIS)

    Takahashi, Akinori; Kikuguchi, Chisato; Morita, Masahiro; Shimodaira, Tetsuhiro; Tokai-Nishizumi, Noriko; Yokoyama, Kazumasa; Ohsugi, Miho; Suzuki, Toru; Yamamoto, Tadashi

    2012-01-01

    Highlights: ► CNOT3 depletion increases the mitotic index. ► CNOT3 inhibits the expression of MAD1. ► CNOT3 destabilizes the MAD1 mRNA. ► MAD1 knockdown attenuates the CNOT3 depletion-induced mitotic arrest. -- Abstract: The stability of mRNA influences the dynamics of gene expression. The CCR4–NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4–NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4–NOT complex, is involved in the regulation of the spindle assembly checkpoint, suggesting that the CCR4–NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.

  20. Involvement of CNOT3 in mitotic progression through inhibition of MAD1 expression

    Energy Technology Data Exchange (ETDEWEB)

    Takahashi, Akinori [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Kikuguchi, Chisato [Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, Okinawa 904-0412 (Japan); Morita, Masahiro; Shimodaira, Tetsuhiro; Tokai-Nishizumi, Noriko; Yokoyama, Kazumasa; Ohsugi, Miho; Suzuki, Toru [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Yamamoto, Tadashi, E-mail: tyamamot@ims.u-tokyo.ac.jp [Division of Oncology, Department of Cancer Biology, Institute of Medical Science, University of Tokyo, Minato-ku, Tokyo 108-8639 (Japan); Cell Signal Unit, Okinawa Institute of Science and Technology, Kunigami, Okinawa 904-0412 (Japan)

    2012-03-09

    Highlights: Black-Right-Pointing-Pointer CNOT3 depletion increases the mitotic index. Black-Right-Pointing-Pointer CNOT3 inhibits the expression of MAD1. Black-Right-Pointing-Pointer CNOT3 destabilizes the MAD1 mRNA. Black-Right-Pointing-Pointer MAD1 knockdown attenuates the CNOT3 depletion-induced mitotic arrest. -- Abstract: The stability of mRNA influences the dynamics of gene expression. The CCR4-NOT complex, the major deadenylase in mammalian cells, shortens the mRNA poly(A) tail and contributes to the destabilization of mRNAs. The CCR4-NOT complex plays pivotal roles in various physiological functions, including cell proliferation, apoptosis, and metabolism. Here, we show that CNOT3, a subunit of the CCR4-NOT complex, is involved in the regulation of the spindle assembly checkpoint, suggesting that the CCR4-NOT complex also plays a part in the regulation of mitosis. CNOT3 depletion increases the population of mitotic-arrested cells and specifically increases the expression of MAD1 mRNA and its protein product that plays a part in the spindle assembly checkpoint. We showed that CNOT3 depletion stabilizes the MAD1 mRNA, and that MAD1 knockdown attenuates the CNOT3 depletion-induced increase of the mitotic index. Basing on these observations, we propose that CNOT3 is involved in the regulation of the spindle assembly checkpoint through its ability to regulate the stability of MAD1 mRNA.

  1. MAPK-activated protein kinase 2 is required for mouse meiotic spindle assembly and kinetochore-microtubule attachment.

    Directory of Open Access Journals (Sweden)

    Ju Yuan

    Full Text Available MAPK-activated protein kinase 2 (MK2, a direct substrate of p38 MAPK, plays key roles in multiple physiological functions in mitosis. Here, we show for the first time the unique distribution pattern of MK2 in meiosis. Phospho-MK2 was localized on bipolar spindle minus ends and along the interstitial axes of homologous chromosomes extending over centromere regions and arm regions at metaphase of first meiosis (MI stage in mouse oocytes. At metaphase of second meiosis (MII stage, p-MK2 was localized on the bipolar spindle minus ends and at the inner centromere region of sister chromatids as dots. Knockdown or inhibition of MK2 resulted in spindle defects. Spindles were surrounded by irregular nondisjunction chromosomes, which were arranged in an amphitelic or syntelic/monotelic manner, or chromosomes detached from the spindles. Kinetochore-microtubule attachments were impaired in MK2-deficient oocytes because spindle microtubules became unstable in response to cold treatment. In addition, homologous chromosome segregation and meiosis progression were inhibited in these oocytes. Our data suggest that MK2 may be essential for functional meiotic bipolar spindle formation, chromosome segregation and proper kinetochore-microtubule attachments.

  2. Bacterial mitotic machineries

    DEFF Research Database (Denmark)

    Gerdes, Kenn; Møller-Jensen, Jakob; Ebersbach, Gitte

    2004-01-01

    Here, we review recent progress that yields fundamental new insight into the molecular mechanisms behind plasmid and chromosome segregation in prokaryotic cells. In particular, we describe how prokaryotic actin homologs form mitotic machineries that segregate DNA before cell division. Thus, the Par......M protein of plasmid R1 forms F actin-like filaments that separate and move plasmid DNA from mid-cell to the cell poles. Evidence from three different laboratories indicate that the morphogenetic MreB protein may be involved in segregation of the bacterial chromosome....

  3. Dlg1 controls planar spindle orientation in the neuroepithelium through direct interaction with LGN.

    Science.gov (United States)

    Saadaoui, Mehdi; Machicoane, Mickaël; di Pietro, Florencia; Etoc, Fred; Echard, Arnaud; Morin, Xavier

    2014-09-15

    Oriented cell divisions are necessary for the development of epithelial structures. Mitotic spindle orientation requires the precise localization of force generators at the cell cortex via the evolutionarily conserved LGN complex. However, polarity cues acting upstream of this complex in vivo in the vertebrate epithelia remain unknown. In this paper, we show that Dlg1 is localized at the basolateral cell cortex during mitosis and is necessary for planar spindle orientation in the chick neuroepithelium. Live imaging revealed that Dlg1 is required for directed spindle movements during metaphase. Mechanistically, we show that direct interaction between Dlg1 and LGN promotes cortical localization of the LGN complex. Furthermore, in human cells dividing on adhesive micropatterns, homogenously localized Dlg1 recruited LGN to the mitotic cortex and was also necessary for proper spindle orientation. We propose that Dlg1 acts primarily to recruit LGN to the cortex and that Dlg1 localization may additionally provide instructive cues for spindle orientation. © 2014 Saadaoui et al.

  4. Expression and function analysis of mitotic checkpoint genes identifies TTK as a potential therapeutic target for human hepatocellular carcinoma.

    Directory of Open Access Journals (Sweden)

    Xiao-Dong Liang

    Full Text Available The mitotic spindle checkpoint (SAC genes have been considered targets of anticancer therapies. Here, we sought to identify the attractive mitotic spindle checkpoint genes appropriate for human hepatocellular carcinoma (HCC therapies. Through expression profile analysis of 137 selected mitotic spindle checkpoint genes in the publicly available microarray datasets, we showed that 13 genes were dramatically up-regulated in HCC tissues compared to normal livers and adjacent non-tumor tissues. A role of the 13 genes in proliferation was evaluated by knocking them down via small interfering RNA (siRNA in HCC cells. As a result, several mitotic spindle checkpoint genes were required for maintaining the proliferation of HCC cells, demonstrated by cell viability assay and soft agar colony formation assay. Then we established sorafenib-resistant sublines of HCC cell lines Huh7 and HepG2. Intriguingly, increased TTK expression was significantly associated with acquired sorafenib-resistance in Huh7, HepG2 cells. More importantly, TTK was observably up-regulated in 46 (86.8% of 53 HCC specimens. A series of in vitro and in vivo functional experiment assays showed that TTK overexpression promoted cell proliferation, anchor-dependent colony formation and resistance to sorafenib of HCC cells; TTK knockdown restrained cell growth, soft agar colony formation and resistance to sorafenib of HCC cells. Collectively, TTK plays an important role in proliferation and sorafenib resistance and could act as a potential therapeutic target for human hepatocellular carcinoma.

  5. WDR62 is associated with the spindle pole and is mutated in human microcephaly

    OpenAIRE

    Nicholas, Adeline K; Khurshid, Maryam; Désir, Julie; Carvalho, Ofélia P; Cox, James J; Thornton, Gemma; Kausar, Rizwana; Ansar, Muhammad; Ahmad, Wasim; Verloes, Alain; Passemard, Sandrine; Misson, Jean-Paul; Lindsay, Susan; Gergely, Fanni; Dobyns, William B

    2010-01-01

    Autosomal recessive primary microcephaly (MCPH) is a disorder of neurodevelopment resulting in a small brain1,2. We identified WDR62 as the second most common cause of MCPH after finding homozygous missense and frame-shifting mutations in seven MCPH families. In human cell lines, we found that WDR62 is a spindle pole protein, as are ASPM and STIL, the MCPH7 and MCHP7 proteins3–5. Mutant WDR62 proteins failed to localize to the mitotic spindle pole. In human and mouse embryonic brain, we found...

  6. Identification of Drosophila mitotic genes by combining co-expression analysis and RNA interference.

    Directory of Open Access Journals (Sweden)

    Maria Patrizia Somma

    2008-07-01

    Full Text Available RNAi screens have, to date, identified many genes required for mitotic divisions of Drosophila tissue culture cells. However, the inventory of such genes remains incomplete. We have combined the powers of bioinformatics and RNAi technology to detect novel mitotic genes. We found that Drosophila genes involved in mitosis tend to be transcriptionally co-expressed. We thus constructed a co-expression-based list of 1,000 genes that are highly enriched in mitotic functions, and we performed RNAi for each of these genes. By limiting the number of genes to be examined, we were able to perform a very detailed phenotypic analysis of RNAi cells. We examined dsRNA-treated cells for possible abnormalities in both chromosome structure and spindle organization. This analysis allowed the identification of 142 mitotic genes, which were subdivided into 18 phenoclusters. Seventy of these genes have not previously been associated with mitotic defects; 30 of them are required for spindle assembly and/or chromosome segregation, and 40 are required to prevent spontaneous chromosome breakage. We note that the latter type of genes has never been detected in previous RNAi screens in any system. Finally, we found that RNAi against genes encoding kinetochore components or highly conserved splicing factors results in identical defects in chromosome segregation, highlighting an unanticipated role of splicing factors in centromere function. These findings indicate that our co-expression-based method for the detection of mitotic functions works remarkably well. We can foresee that elaboration of co-expression lists using genes in the same phenocluster will provide many candidate genes for small-scale RNAi screens aimed at completing the inventory of mitotic proteins.

  7. Bipolar Disorder

    Science.gov (United States)

    Bipolar disorder is a serious mental illness. People who have it go through unusual mood changes. They go ... The down feeling is depression. The causes of bipolar disorder aren't always clear. It runs in families. ...

  8. A Role for the Chaperone Complex BAG3-HSPB8 in Actin Dynamics, Spindle Orientation and Proper Chromosome Segregation during Mitosis

    Science.gov (United States)

    Fuchs, Margit; Lambert, Herman; Jetté, Alexandra; Elowe, Sabine; Landry, Jacques; Lavoie, Josée N.

    2015-01-01

    The co-chaperone BAG3, in complex with the heat shock protein HSPB8, plays a role in protein quality control during mechanical strain. It is part of a multichaperone complex that senses damaged cytoskeletal proteins and orchestrates their seclusion and/or degradation by selective autophagy. Here we describe a novel role for the BAG3-HSPB8 complex in mitosis, a process involving profound changes in cell tension homeostasis. BAG3 is hyperphosphorylated at mitotic entry and localizes to centrosomal regions. BAG3 regulates, in an HSPB8-dependent manner, the timely congression of chromosomes to the metaphase plate by influencing the three-dimensional positioning of the mitotic spindle. Depletion of BAG3 caused defects in cell rounding at metaphase and dramatic blebbing of the cortex associated with abnormal spindle rotations. Similar defects were observed upon silencing of the autophagic receptor p62/SQSTM1 that contributes to BAG3-mediated selective autophagy pathway. Mitotic cells depleted of BAG3, HSPB8 or p62/SQSTM1 exhibited disorganized actin-rich retraction fibres, which are proposed to guide spindle orientation. Proper spindle positioning was rescued in BAG3-depleted cells upon addition of the lectin concanavalin A, which restores cortex rigidity. Together, our findings suggest the existence of a so-far unrecognized quality control mechanism involving BAG3, HSPB8 and p62/SQSTM1 for accurate remodelling of actin-based mitotic structures that guide spindle orientation. PMID:26496431

  9. Phospho-Bcl-xL(Ser62) influences spindle assembly and chromosome segregation during mitosis.

    Science.gov (United States)

    Wang, Jianfang; Beauchemin, Myriam; Bertrand, Richard

    2014-01-01

    Functional analysis of a series of phosphorylation mutants reveals that Bcl-xL(Ser62Ala) influences cell entry into anaphase and mitotic exit in taxol-exposed cells compared with cells expressing wild-type Bcl-xL or a series of other phosphorylation mutants, an effect that appears to be independent of its anti-apoptotic activity. During normal mitosis progression, Bcl-xL(Ser62) is strongly phosphorylated by PLK1 and MAPK14/SAPKp38α at the prometaphase, metaphase, and the anaphase boundaries, while it is de-phosphorylated at telophase and cytokinesis. Phospho-Bcl-xL(Ser62) localizes in centrosomes with γ-tubulin and in the mitotic cytosol with some spindle-assembly checkpoint signaling components, including PLK1, BubR1, and Mad2. In taxol- and nocodazole-exposed cells, phospho-Bcl-xL(Ser62) also binds to Cdc20- Mad2-, BubR1-, and Bub3-bound complexes, while Bcl-xL(Ser62Ala) does not. Silencing Bcl-xL expression and expressing the phosphorylation mutant Bcl-xL(Ser62Ala) lead to an increased number of cells harboring mitotic spindle defects including multipolar spindle, chromosome lagging and bridging, aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h. Together, the data indicate that during mitosis, Bcl-xL(Ser62) phosphorylation impacts on spindle assembly and chromosome segregation, influencing chromosome stability. Observations of mitotic cells harboring aneuploidy with micro-, bi-, or multi-nucleated cells, and cells that fail to resolve undergo mitosis within 6 h were also made with cells expressing the phosphorylation mutant Bcl-xL(Ser49Ala) and dual mutant Bcl-xL(Ser49/62Ala).

  10. Drosophila melanogaster mini spindles TOG3 utilizes unique structural elements to promote domain stability and maintain a TOG1- and TOG2-like tubulin-binding surface.

    Science.gov (United States)

    Howard, Amy E; Fox, Jaime C; Slep, Kevin C

    2015-04-17

    Microtubule-associated proteins regulate microtubule (MT) dynamics spatially and temporally, which is essential for proper formation of the bipolar mitotic spindle. The XMAP215 family is comprised of conserved microtubule-associated proteins that use an array of tubulin-binding tumor overexpressed gene (TOG) domains, consisting of six (A-F) Huntingtin, elongation factor 3, protein phosphatase 2A, target of rapamycin (HEAT) repeats, to robustly increase MT plus-end polymerization rates. Recent work showed that TOG domains have differentially conserved architectures across the array, with implications for position-dependent TOG domain tubulin binding activities and function within the XMAP215 MT polymerization mechanism. Although TOG domains 1, 2, and 4 are well described, structural and mechanistic information characterizing TOG domains 3 and 5 is outstanding. Here, we present the structure and characterization of Drosophila melanogaster Mini spindles (Msps) TOG3. Msps TOG3 has two unique features as follows: the first is a C-terminal tail that stabilizes the ultimate four HEAT repeats (HRs), and the second is a unique architecture in HR B. Structural alignments of TOG3 with other TOG domain structures show that the architecture of TOG3 is most similar to TOG domains 1 and 2 and diverges from TOG4. Docking TOG3 onto recently solved Stu2 TOG1· and TOG2·tubulin complex structures suggests that TOG3 uses similarly conserved tubulin-binding intra-HEAT loop residues to engage α- and β-tubulin. This indicates that TOG3 has maintained a TOG1- and TOG2-like TOG-tubulin binding mode despite structural divergence. The similarity of TOG domains 1-3 and the divergence of TOG4 suggest that a TOG domain array with polarized structural diversity may play a key mechanistic role in XMAP215-dependent MT polymerization activity. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. The NuMA-related Mud protein binds Pins and regulates spindle orientation in Drosophila neuroblasts.

    Science.gov (United States)

    Siller, Karsten H; Cabernard, Clemens; Doe, Chris Q

    2006-06-01

    Asymmetric cell division generates cell diversity during development and regulates stem-cell self-renewal in Drosophila and mammals. In Drosophila, neuroblasts align their spindle with a cortical Partner of Inscuteable (Pins)-G alpha i crescent to divide asymmetrically, but the link between cortical polarity and the mitotic spindle is poorly understood. Here, we show that Pins directly binds, and coimmunoprecipitates with, the NuMA-related Mushroom body defect (Mud) protein. Pins recruits Mud to the neuroblast apical cortex, and Mud is also strongly localized to centrosome/spindle poles, in a similar way to NuMA. In mud mutants, cortical polarity is normal, but the metaphase spindle frequently fails to align with the cortical polarity axis. When spindle orientation is orthogonal to cell polarity, symmetric division occurs. We propose that Mud is a functional orthologue of mammalian NuMA and Caenorhabditis elegans Lin-5, and that Mud coordinates spindle orientation with cortical polarity to promote asymmetric cell division.

  12. Spatial Reorganization of the Endoplasmic Reticulum during Mitosis Relies on Mitotic Kinase Cyclin A in the Early Drosophila Embryo

    Science.gov (United States)

    Bergman, Zane J.; Mclaurin, Justin D.; Eritano, Anthony S.; Johnson, Brittany M.; Sims, Amanda Q.; Riggs, Blake

    2015-01-01

    Mitotic cyclin-dependent kinase with their cyclin partners (cyclin:Cdks) are the master regulators of cell cycle progression responsible for regulating a host of activities during mitosis. Nuclear mitotic events, including chromosome condensation and segregation have been directly linked to Cdk activity. However, the regulation and timing of cytoplasmic mitotic events by cyclin:Cdks is poorly understood. In order to examine these mitotic cytoplasmic events, we looked at the dramatic changes in the endoplasmic reticulum (ER) during mitosis in the early Drosophila embryo. The dynamic changes of the ER can be arrested in an interphase state by inhibition of either DNA or protein synthesis. Here we show that this block can be alleviated by micro-injection of Cyclin A (CycA) in which defined mitotic ER clusters gathered at the spindle poles. Conversely, micro-injection of Cyclin B (CycB) did not affect spatial reorganization of the ER, suggesting CycA possesses the ability to initiate mitotic ER events in the cytoplasm. Additionally, RNAi-mediated simultaneous inhibition of all 3 mitotic cyclins (A, B and B3) blocked spatial reorganization of the ER. Our results suggest that mitotic ER reorganization events rely on CycA and that control and timing of nuclear and cytoplasmic events during mitosis may be defined by release of CycA from the nucleus as a consequence of breakdown of the nuclear envelope. PMID:25689737

  13. WDR62 is associated with the spindle pole and is mutated in human microcephaly.

    Science.gov (United States)

    Nicholas, Adeline K; Khurshid, Maryam; Désir, Julie; Carvalho, Ofélia P; Cox, James J; Thornton, Gemma; Kausar, Rizwana; Ansar, Muhammad; Ahmad, Wasim; Verloes, Alain; Passemard, Sandrine; Misson, Jean-Paul; Lindsay, Susan; Gergely, Fanni; Dobyns, William B; Roberts, Emma; Abramowicz, Marc; Woods, C Geoffrey

    2010-11-01

    Autosomal recessive primary microcephaly (MCPH) is a disorder of neurodevelopment resulting in a small brain. We identified WDR62 as the second most common cause of MCPH after finding homozygous missense and frame-shifting mutations in seven MCPH families. In human cell lines, we found that WDR62 is a spindle pole protein, as are ASPM and STIL, the MCPH7 and MCHP7 proteins. Mutant WDR62 proteins failed to localize to the mitotic spindle pole. In human and mouse embryonic brain, we found that WDR62 expression was restricted to neural precursors undergoing mitosis. These data lend support to the hypothesis that the exquisite control of the cleavage furrow orientation in mammalian neural precursor cell mitosis, controlled in great part by the centrosomes and spindle poles, is critical both in causing MCPH when perturbed and, when modulated, generating the evolutionarily enlarged human brain.

  14. Phosphatase-regulated recruitment of the spindle- and kinetochore-associated (Ska complex to kinetochores

    Directory of Open Access Journals (Sweden)

    Sushama Sivakumar

    2017-11-01

    Full Text Available Kinetochores move chromosomes on dynamic spindle microtubules and regulate signaling of the spindle checkpoint. The spindle- and kinetochore-associated (Ska complex, a hexamer composed of two copies of Ska1, Ska2 and Ska3, has been implicated in both roles. Phosphorylation of kinetochore components by the well-studied mitotic kinases Cdk1, Aurora B, Plk1, Mps1, and Bub1 regulate chromosome movement and checkpoint signaling. Roles for the opposing phosphatases are more poorly defined. Recently, we showed that the C terminus of Ska1 recruits protein phosphatase 1 (PP1 to kinetochores. Here we show that PP1 and protein phosphatase 2A (PP2A both promote accumulation of Ska at kinetochores. Depletion of PP1 or PP2A by siRNA reduces Ska binding at kinetochores, impairs alignment of chromosomes to the spindle midplane, and causes metaphase delay or arrest, phenotypes that are also seen after depletion of Ska. Artificial tethering of PP1 to the outer kinetochore protein Nuf2 promotes Ska recruitment to kinetochores, and it reduces but does not fully rescue chromosome alignment and metaphase arrest defects seen after Ska depletion. We propose that Ska has multiple functions in promoting mitotic progression and that kinetochore-associated phosphatases function in a positive feedback cycle to reinforce Ska complex accumulation at kinetochores.

  15. Mitotic cells contract actomyosin cortex and generate pressure to round against or escape epithelial confinement

    Science.gov (United States)

    Sorce, Barbara; Escobedo, Carlos; Toyoda, Yusuke; Stewart, Martin P.; Cattin, Cedric J.; Newton, Richard; Banerjee, Indranil; Stettler, Alexander; Roska, Botond; Eaton, Suzanne; Hyman, Anthony A.; Hierlemann, Andreas; Müller, Daniel J.

    2015-01-01

    Little is known about how mitotic cells round against epithelial confinement. Here, we engineer micropillar arrays that subject cells to lateral mechanical confinement similar to that experienced in epithelia. If generating sufficient force to deform the pillars, rounding epithelial (MDCK) cells can create space to divide. However, if mitotic cells cannot create sufficient space, their rounding force, which is generated by actomyosin contraction and hydrostatic pressure, pushes the cell out of confinement. After conducting mitosis in an unperturbed manner, both daughter cells return to the confinement of the pillars. Cells that cannot round against nor escape confinement cannot orient their mitotic spindles and more likely undergo apoptosis. The results highlight how spatially constrained epithelial cells prepare for mitosis: either they are strong enough to round up or they must escape. The ability to escape from confinement and reintegrate after mitosis appears to be a basic property of epithelial cells. PMID:26602832

  16. Spindle frequency activity in the sleep EEG: individual differences and topographic distribution.

    Science.gov (United States)

    Werth, E; Achermann, P; Dijk, D J; Borbély, A A

    1997-11-01

    The brain topography of EEG power spectra in the frequency range of sleep spindles was investigated in 34 sleep recordings from 20 healthy young men. Referential (F3-A2, C3-A2, P3-A2 and O1-A2) and bipolar derivations (F3-C3, C3-P3 and P3-O1) along the anteroposterior axis were used. Sleep spindles gave rise to a distinct peak in the EEG power spectrum. The distribution of the peak frequencies pooled over subjects and derivations showed a bimodal pattern with modes at 11.5 and 13.0 Hz, and a trough at 12.25 Hz. The large inter-subject variation in peak frequency (range: 1.25 Hz) contrasted with the small intra-subject variation between derivations, non-REM sleep episodes and different nights. In some individuals and/or some derivations, only a single spindle peak was present. The topographic distributions from referential and bipolar recordings showed differences. The power showed a declining trend over consecutive non-REM sleep episodes in the low range of spindle frequency activity and a rising trend in the high range. The functional and topographic heterogeneity of sleep spindles in conjunction with the intra-subject stability of their frequency are important characteristics for the analysis of sleep regulation on the basis of the EEG.

  17. Spindle pole cohesion requires glycosylation-mediated localization of NuMA.

    Science.gov (United States)

    Magescas, Jérémy; Sengmanivong, Lucie; Viau, Amandine; Mayeux, Adeline; Dang, Tien; Burtin, Martine; Nilsson, Ulf J; Leffler, Hakon; Poirier, Françoise; Terzi, Fabiola; Delacour, Delphine

    2017-05-03

    Glycosylation is critical for the regulation of several cellular processes. One glycosylation pathway, the unusual O-linked β-N-acetylglucosamine glycosylation (O-GlcNAcylation) has been shown to be required for proper mitosis, likely through a subset of proteins that are O-GlcNAcylated during metaphase. As lectins bind glycosylated proteins, we asked if specific lectins interact with mitotic O-GlcNAcylated proteins during metaphase to ensure correct cell division. Galectin-3, a small soluble lectin of the Galectin family, is an excellent candidate, as it has been previously described as a transient centrosomal component in interphase and mitotic epithelial cells. In addition, it has recently been shown to associate with basal bodies in motile cilia, where it stabilizes the microtubule-organizing center (MTOC). Using an experimental mouse model of chronic kidney disease and human epithelial cell lines, we investigate the role of Galectin-3 in dividing epithelial cells. Here we find that Galectin-3 is essential for metaphase where it associates with NuMA in an O-GlcNAcylation-dependent manner. We provide evidence that the NuMA-Galectin-3 interaction is important for mitotic spindle cohesion and for stable NuMA localization to the spindle pole, thus revealing that Galectin-3 is a novel contributor to epithelial mitotic progress.

  18. Phosphorylated ERK5/BMK1 transiently accumulates within division spindles in mouse oocytes and preimplantation embryos

    Directory of Open Access Journals (Sweden)

    Maria A. Ciemerych

    2011-10-01

    Full Text Available MAP kinases of the ERK family play important roles in oocyte maturation, fertilization, and early embryo development. The role of the signaling pathway involving ERK5 MAP kinase during meiotic and mitotic M-phase of the cell cycle is not well known. Here, we studied the localization of the phosphorylated, and thus potentially activated, form of ERK5 in mouse maturing oocytes and mitotically dividing early embryos. We show that phosphorylation/dephosphorylation, i.e. likely activation/inactivation of ERK5, correlates with M-phase progression. Phosphorylated form of ERK5 accumulates in division spindle of both meiotic and mitotic cells, and precisely co-localizes with spindle microtubules at metaphase. This localization changes drastically in the anaphase, when phospho-ERK5 completely disappears from microtubules and transits to the cytoplasmic granular, vesicle-like structures. In telophase oocytes it becomes incorporated into the midbody. Dynamic changes in the localization of phospho-ERK5 suggests that it may play an important role both in meiotic and mitotic division. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 3, 528–534

  19. NuMA Phosphorylation by Aurora-A Orchestrates Spindle Orientation.

    Science.gov (United States)

    Gallini, Sara; Carminati, Manuel; De Mattia, Fabiola; Pirovano, Laura; Martini, Emanuele; Oldani, Amanda; Asteriti, Italia Anna; Guarguaglini, Giulia; Mapelli, Marina

    2016-02-22

    Spindle positioning is essential for tissue morphogenesis and homeostasis. The signaling network synchronizing spindle placement with mitotic progression relies on timely recruitment at the cell cortex of NuMA:LGN:Gαi complexes, in which NuMA acts as a receptor for the microtubule motor Dynein. To study the implication of Aurora-A in spindle orientation, we developed protocols for the partial inhibition of its activity. Under these conditions, in metaphase NuMA and Dynein accumulate abnormally at the spindle poles and do not reach the cortex, while the cortical distribution of LGN remains unperturbed. FRAP experiments revealed that Aurora-A governs the dynamic exchange between the cytoplasmic and the spindle pole-localized pools of NuMA. We show that Aurora-A phosphorylates directly the C terminus of NuMA on three Ser residues, of which Ser1969 determines the dynamic behavior and the spindle orientation functions of NuMA. Most interestingly, we identify a new microtubule-binding domain of NuMA, which does not overlap with the LGN-binding motif. Our study demonstrates that in metaphase the direct phosphorylation of NuMA by Aurora-A controls its cortical enrichment, and that this is the major event underlying the spindle orientation functions of Aurora-A in transformed and non-transformed cells in culture. Phosphorylation of NuMA by Aurora-A does not affect its affinity for microtubules or for LGN but rather determines the mobility of the protein at the spindle poles. The finding that NuMA can associate concomitantly with LGN and microtubules suggests that its microtubule-binding activity contributes to anchor Dynein-loaded microtubule +TIPs at cortical sites with LGN. Copyright © 2016 Elsevier Ltd. All rights reserved.

  20. Multiple Duties for Spindle Assembly Checkpoint Kinases in Meiosis.

    Science.gov (United States)

    Marston, Adele L; Wassmann, Katja

    2017-01-01

    Cell division in mitosis and meiosis is governed by evolutionary highly conserved protein kinases and phosphatases, controlling the timely execution of key events such as nuclear envelope breakdown, spindle assembly, chromosome attachment to the spindle and chromosome segregation, and cell cycle exit. In mitosis, the spindle assembly checkpoint (SAC) controls the proper attachment to and alignment of chromosomes on the spindle. The SAC detects errors and induces a cell cycle arrest in metaphase, preventing chromatid separation. Once all chromosomes are properly attached, the SAC-dependent arrest is relieved and chromatids separate evenly into daughter cells. The signaling cascade leading to checkpoint arrest depends on several protein kinases that are conserved from yeast to man. In meiosis, haploid cells containing new genetic combinations are generated from a diploid cell through two specialized cell divisions. Though apparently less robust, SAC control also exists in meiosis. Recently, it has emerged that SAC kinases have additional roles in executing accurate chromosome segregation during the meiotic divisions. Here, we summarize the main differences between mitotic and meiotic cell divisions, and explain why meiotic divisions pose special challenges for correct chromosome segregation. The less-known meiotic roles of the SAC kinases are described, with a focus on two model systems: yeast and mouse oocytes. The meiotic roles of the canonical checkpoint kinases Bub1, Mps1, the pseudokinase BubR1 (Mad3), and Aurora B and C (Ipl1) will be discussed. Insights into the molecular signaling pathways that bring about the special chromosome segregation pattern during meiosis will help us understand why human oocytes are so frequently aneuploid.

  1. Impaired mitotic progression and preimplantation lethality in mice lacking OMCG1, a new evolutionarily conserved nuclear protein

    DEFF Research Database (Denmark)

    Artus, Jérôme; Vandormael-Pournin, Sandrine; Frödin, Morten

    2005-01-01

    -type-specific function, indicating that many aspects of cell cycle regulation during mammalian embryo development remain to be elucidated. Here, we report on the characterization of a new gene, Omcg1, which codes for a nuclear zinc finger protein. Embryos lacking Omcg1 die by the end of preimplantation development....... In vitro cultured Omcg1-null blastocysts exhibit a dramatic reduction in the total cell number, a high mitotic index, and the presence of abnormal mitotic figures. Importantly, we found that Omcg1 disruption results in the lengthening of M phase rather than in a mitotic block. We show that the mitotic...... delay in Omcg1-/- embryos is associated with neither a dysfunction of the spindle checkpoint nor abnormal global histone modifications. Taken together, these results suggest that Omcg1 is an important regulator of the cell cycle in the preimplantation embryo....

  2. NuMA-related LIN-5, ASPM-1, calmodulin and dynein promote meiotic spindle rotation independently of cortical LIN-5/GPR/Galpha.

    Science.gov (United States)

    van der Voet, Monique; Berends, Christian W H; Perreault, Audrey; Nguyen-Ngoc, Tu; Gönczy, Pierre; Vidal, Marc; Boxem, Mike; van den Heuvel, Sander

    2009-03-01

    The spindle apparatus dictates the plane of cell cleavage, which is critical in the choice between symmetric or asymmetric division. Spindle positioning is controlled by an evolutionarily conserved pathway, which involves LIN-5/GPR-1/2/Galpha in Caenorhabditis elegans, Mud/Pins/Galpha in Drosophila and NuMA/LGN/Galpha in humans. GPR-1/2 and Galpha localize LIN-5 to the cell cortex, which engages dynein and controls the cleavage plane during early mitotic divisions in C. elegans. Here we identify ASPM-1 (abnormal spindle-like, microcephaly-associated) as a novel LIN-5 binding partner. ASPM-1, together with calmodulin (CMD-1), promotes meiotic spindle organization and the accumulation of LIN-5 at meiotic and mitotic spindle poles. Spindle rotation during maternal meiosis is independent of GPR-1/2 and Galpha, yet requires LIN-5, ASPM-1, CMD-1 and dynein. Our data support the existence of two distinct LIN-5 complexes that determine localized dynein function: LIN-5/GPR-1/2/Galpha at the cortex, and LIN-5/ASPM-1/CMD-1 at spindle poles. These functional interactions may be conserved in mammals, with implications for primary microcephaly.

  3. Premature Sister Chromatid Separation Is Poorly Detected by the Spindle Assembly Checkpoint as a Result of System-Level Feedback

    Directory of Open Access Journals (Sweden)

    Mihailo Mirkovic

    2015-10-01

    Full Text Available Sister chromatid cohesion, mediated by the cohesin complex, is essential for faithful mitosis. Nevertheless, evidence suggests that the surveillance mechanism that governs mitotic fidelity, the spindle assembly checkpoint (SAC, is not robust enough to halt cell division when cohesion loss occurs prematurely. The mechanism behind this poor response is not properly understood. Using developing Drosophila brains, we show that full sister chromatid separation elicits a weak checkpoint response resulting in abnormal mitotic exit after a short delay. Quantitative live-cell imaging approaches combined with mathematical modeling indicate that weak SAC activation upon cohesion loss is caused by weak signal generation. This is further attenuated by several feedback loops in the mitotic signaling network. We propose that multiple feedback loops involving cyclin-dependent kinase 1 (Cdk1 gradually impair error-correction efficiency and accelerate mitotic exit upon premature loss of cohesion. Our findings explain how cohesion defects may escape SAC surveillance.

  4. Using Oscillating Sounds to Manipulate Sleep Spindles.

    Science.gov (United States)

    Antony, James W; Paller, Ken A

    2017-03-01

    EEG oscillations known as sleep spindles have been linked with various aspects of cognition, but the specific functions they signal remain controversial. Two types of EEG sleep spindles have been distinguished: slow spindles at 11-13.5 Hz and fast spindles at 13.5-16 Hz. Slow spindles exhibit a frontal scalp topography, whereas fast spindles exhibit a posterior scalp topography and have been preferentially linked with memory consolidation during sleep. To advance understanding beyond that provided from correlative studies of spindles, we aimed to develop a new method to systematically manipulate spindles. We presented repeating bursts of oscillating white noise to people during a 90-min afternoon nap. During stage 2 and slow-wave sleep, oscillations were embedded within contiguous 10-s stimulation intervals, each comprising 2 s of white noise amplitude modulated at 12 Hz (targeting slow spindles), 15 Hz (targeting fast spindles), or 50 Hz followed by 8 s of constant white noise. During oscillating stimulation compared to constant stimulation, parietal EEG recordings showed more slow spindles in the 12-Hz condition, more fast spindles in the 15-Hz condition, and no change in the 50-Hz control condition. These effects were topographically selective, and were absent in frontopolar EEG recordings, where slow spindle density was highest. Spindles during stimulation were similar to spontaneous spindles in standard physiological features, including duration and scalp distribution. These results define a new method to selectively and noninvasively manipulate spindles through acoustic resonance, while also providing new evidence for functional distinctions between the 2 types of EEG spindles. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e-mail journals.permissions@oup.com.

  5. A functional relationship between NuMA and kid is involved in both spindle organization and chromosome alignment in vertebrate cells.

    Science.gov (United States)

    Levesque, Aime A; Howard, Louisa; Gordon, Michael B; Compton, Duane A

    2003-09-01

    We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of Kid and NuMA function. In addition, chromosomes failed to align efficiently at the spindle equator after simultaneous perturbation of Kid and NuMA despite appropriate kinetochore-microtubule interactions that generated chromosome movement at normal velocities. These data indicate that a functional relationship between the chromokinesin Kid and the spindle pole organizing protein NuMA influences spindle morphology, and we propose that this occurs because NuMA forms functional linkages between kinetochore and nonkinetochore microtubules at spindle poles. In addition, these data show that both Kid and NuMA contribute to chromosome alignment in mammalian cells.

  6. A Functional Relationship between NuMA and Kid Is Involved in Both Spindle Organization and Chromosome Alignment in Vertebrate CellsV⃞

    Science.gov (United States)

    Levesque, Aime A.; Howard, Louisa; Gordon, Michael B.; Compton, Duane A.

    2003-01-01

    We examined spindle morphology and chromosome alignment in vertebrate cells after simultaneous perturbation of the chromokinesin Kid and either NuMA, CENP-E, or HSET. Spindle morphology and chromosome alignment after simultaneous perturbation of Kid and either HSET or CENP-E were no different from when either HSET or CENP-E was perturbed alone. However, short bipolar spindles with organized poles formed after perturbation of both Kid and NuMA in stark contrast to splayed spindle poles observed after perturbation of NuMA alone. Spindles were disorganized if Kid, NuMA, and HSET were perturbed, indicating that HSET is sufficient for spindle organization in the absence of Kid and NuMA function. In addition, chromosomes failed to align efficiently at the spindle equator after simultaneous perturbation of Kid and NuMA despite appropriate kinetochore-microtubule interactions that generated chromosome movement at normal velocities. These data indicate that a functional relationship between the chromokinesin Kid and the spindle pole organizing protein NuMA influences spindle morphology, and we propose that this occurs because NuMA forms functional linkages between kinetochore and nonkinetochore microtubules at spindle poles. In addition, these data show that both Kid and NuMA contribute to chromosome alignment in mammalian cells. PMID:12972545

  7. Misato Controls Mitotic Microtubule Generation by Stabilizing the TCP-1 Tubulin Chaperone Complex [corrected].

    Science.gov (United States)

    Palumbo, Valeria; Pellacani, Claudia; Heesom, Kate J; Rogala, Kacper B; Deane, Charlotte M; Mottier-Pavie, Violaine; Gatti, Maurizio; Bonaccorsi, Silvia; Wakefield, James G

    2015-06-29

    Mitotic spindles are primarily composed of microtubules (MTs), generated by polymerization of α- and β-Tubulin hetero-dimers. Tubulins undergo a series of protein folding and post-translational modifications in order to fulfill their functions. Defects in Tubulin polymerization dramatically affect spindle formation and disrupt chromosome segregation. We recently described a role for the product of the conserved misato (mst) gene in regulating mitotic MT generation in flies, but the molecular function of Mst remains unknown. Here, we use affinity purification mass spectrometry (AP-MS) to identify interacting partners of Mst in the Drosophila embryo. We demonstrate that Mst associates stoichiometrically with the hetero-octameric Tubulin Chaperone Protein-1 (TCP-1) complex, with the hetero-hexameric Tubulin Prefoldin complex, and with proteins having conserved roles in generating MT-competent Tubulin. We show that RNAi-mediated in vivo depletion of any TCP-1 subunit phenocopies the effects of mutations in mst or the Prefoldin-encoding gene merry-go-round (mgr), leading to monopolar and disorganized mitotic spindles containing few MTs. Crucially, we demonstrate that Mst, but not Mgr, is required for TCP-1 complex stability and that both the efficiency of Tubulin polymerization and Tubulin stability are drastically compromised in mst mutants. Moreover, our structural bioinformatic analyses indicate that Mst resembles the three-dimensional structure of Tubulin monomers and might therefore occupy the TCP-1 complex central cavity. Collectively, our results suggest that Mst acts as a co-factor of the TCP-1 complex, playing an essential role in the Tubulin-folding processes required for proper assembly of spindle MTs. Copyright © 2015 The Authors. Published by Elsevier Ltd.. All rights reserved.

  8. Nap sleep spindle correlates of intelligence.

    Science.gov (United States)

    Ujma, Péter P; Bódizs, Róbert; Gombos, Ferenc; Stintzing, Johannes; Konrad, Boris N; Genzel, Lisa; Steiger, Axel; Dresler, Martin

    2015-11-26

    Sleep spindles are thalamocortical oscillations in non-rapid eye movement (NREM) sleep, that play an important role in sleep-related neuroplasticity and offline information processing. Several studies with full-night sleep recordings have reported a positive association between sleep spindles and fluid intelligence scores, however more recently it has been shown that only few sleep spindle measures correlate with intelligence in females, and none in males. Sleep spindle regulation underlies a circadian rhythm, however the association between spindles and intelligence has not been investigated in daytime nap sleep so far. In a sample of 86 healthy male human subjects, we investigated the correlation between fluid intelligence and sleep spindle parameters in an afternoon nap of 100 minutes. Mean sleep spindle length, amplitude and density were computed for each subject and for each derivation for both slow and fast spindles. A positive association was found between intelligence and slow spindle duration, but not any other sleep spindle parameter. As a positive correlation between intelligence and slow sleep spindle duration in full-night polysomnography has only been reported in females but not males, our results suggest that the association between intelligence and sleep spindles is more complex than previously assumed.

  9. Cardiac spindle cell hemangioma: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ju Young; Lee, In Jae; Min, Kwang Sun; Jeon, Eui Yong; Lee, Yul; Bae, Sang Hoon [Hallym University College of Medicine, Anyang (Korea, Republic of)

    2007-04-15

    Spindle cell hemangioma is an uncommon vascular lesion histologically resembling a cavernous hemangioma and Kaposi's sarcoma with a predilection for the extremities. There are no radiologic reports concerning cardiac spindle cell hemangioma in the current literature. We report here a case of cardiac spindle cell hemangioma.

  10. Ki-67 acts as a biological surfactant to disperse mitotic chromosomes

    Science.gov (United States)

    Cuylen, Sara; Blaukopf, Claudia; Politi, Antonio Z.; Müller-Reichert, Thomas; Neumann, Beate; Poser, Ina; Ellenberg, Jan; Hyman, Anthony A.; Gerlich, Daniel W.

    2016-01-01

    Summary Eukaryotic genomes are partitioned into chromosomes, which during mitosis form compact and spatially well-separated mechanical bodies1–3.This enables chromosomes to move independently of each other for segregation of precisely one copy of the genome to each of the nascent daughter cells. Despite insights into the spatial organization of mitotic chromosomes4 and the discovery of proteins at the chromosome surface3,5,6, the molecular and biophysical basis of mitotic chromosome individuality have remained unclear. We report that Ki-67, a component of the mitotic chromosome periphery, prevents chromosomes from collapsing into a single chromatin mass after nuclear envelope disassembly, thus enabling independent chromosome motility and efficient interactions with the mitotic spindle. The chromosome separation function of Ki-67 is not confined within a specific protein domain but correlates with size and net charge of truncation mutants that apparently lack secondary structure. This suggests that Ki-67 forms a steric and electrical barrier, similar to surface-active agents (surfactants) that disperse particles or phase-separated liquid droplets in solvents. Fluorescence correlation spectroscopy showed a high surface density of Ki-67 and dual-color labeling of both protein termini revealed an extended molecular conformation, indicating brush-like arrangements that are characteristic for polymeric surfactants. Our study thus elucidates a biomechanical role of the mitotic chromosome periphery and suggests that natural proteins can function as surfactants in intracellular compartmentalization. PMID:27362226

  11. Profiling DNA damage response following mitotic perturbations

    DEFF Research Database (Denmark)

    Pedersen, Ronni Sølvhøi; Karemore, Gopal; Gudjonsson, Thorkell

    2016-01-01

    Genome integrity relies on precise coordination between DNA replication and chromosome segregation. Whereas replication stress attracted much attention, the consequences of mitotic perturbations for genome integrity are less understood. Here, we knockdown 47 validated mitotic regulators to show t...

  12. Theory of meiotic spindle assembly

    Science.gov (United States)

    Furthauer, Sebastian; Foster, Peter; Needleman, Daniel; Shelley, Michael

    2016-11-01

    The meiotic spindle is a biological structure that self assembles from the intracellular medium to separate chromosomes during meiosis. It consists of filamentous microtubule (MT) proteins that interact through the fluid in which they are suspended and via the associated molecules that orchestrate their behavior. We aim to understand how the interplay between fluid medium, MTs, and regulatory proteins allows this material to self-organize into the spindle's highly stereotyped shape. To this end we develop a continuum model that treats the spindle as an active liquid crystal with MT turnover. In this active material, molecular motors, such as dyneins which collect MT minus ends and kinesins which slide MTs past each other, generate active fluid and material stresses. Moreover nucleator proteins that are advected with and transported along MTs control the nucleation and depolymerization of MTs. This theory captures the growth process of meiotic spindles, their shapes, and the essential features of many perturbation experiments. It thus provides a framework to think about the physics of this complex biological suspension.

  13. Dishevelled binds the Discs large 'Hook' domain to activate GukHolder-dependent spindle positioning in Drosophila.

    Directory of Open Access Journals (Sweden)

    Joshua D Garcia

    Full Text Available Communication between cortical cell polarity cues and the mitotic spindle ensures proper orientation of cell divisions within complex tissues. Defects in mitotic spindle positioning have been linked to various developmental disorders and have recently emerged as a potential contributor to tumorigenesis. Despite the importance of this process to human health, the molecular mechanisms that regulate spindle orientation are not fully understood. Moreover, it remains unclear how diverse cortical polarity complexes might cooperate to influence spindle positioning. We and others have demonstrated spindle orientation roles for Dishevelled (Dsh, a key regulator of planar cell polarity, and Discs large (Dlg, a conserved apico-basal cell polarity regulator, effects which were previously thought to operate within distinct molecular pathways. Here we identify a novel direct interaction between the Dsh-PDZ domain and the alternatively spliced "I3-insert" of the Dlg-Hook domain, thus establishing a potential convergent Dsh/Dlg pathway. Furthermore, we identify a Dlg sequence motif necessary for the Dsh interaction that shares homology to the site of Dsh binding in the Frizzled receptor. Expression of Dsh enhanced Dlg-mediated spindle positioning similar to deletion of the Hook domain. This Dsh-mediated activation was dependent on the Dlg-binding partner, GukHolder (GukH. These results suggest that Dsh binding may regulate core interdomain conformational dynamics previously described for Dlg. Together, our results identify Dlg as an effector of Dsh signaling and demonstrate a Dsh-mediated mechanism for the activation of Dlg/GukH-dependent spindle positioning. Cooperation between these two evolutionarily-conserved cell polarity pathways could have important implications to both the development and maintenance of tissue homeostasis in animals.

  14. Evidence of Selection against Complex Mitotic-Origin Aneuploidy during Preimplantation Development

    Science.gov (United States)

    McCoy, Rajiv C.; Demko, Zachary P.; Ryan, Allison; Banjevic, Milena; Hill, Matthew; Sigurjonsson, Styrmir; Rabinowitz, Matthew; Petrov, Dmitri A.

    2015-01-01

    Whole-chromosome imbalances affect over half of early human embryos and are the leading cause of pregnancy loss. While these errors frequently arise in oocyte meiosis, many such whole-chromosome abnormalities affecting cleavage-stage embryos are the result of chromosome missegregation occurring during the initial mitotic cell divisions. The first wave of zygotic genome activation at the 4–8 cell stage results in the arrest of a large proportion of embryos, the vast majority of which contain whole-chromosome abnormalities. Thus, the full spectrum of meiotic and mitotic errors can only be detected by sampling after the initial cell divisions, but prior to this selective filter. Here, we apply 24-chromosome preimplantation genetic screening (PGS) to 28,052 single-cell day-3 blastomere biopsies and 18,387 multi-cell day-5 trophectoderm biopsies from 6,366 in vitro fertilization (IVF) cycles. We precisely characterize the rates and patterns of whole-chromosome abnormalities at each developmental stage and distinguish errors of meiotic and mitotic origin without embryo disaggregation, based on informative chromosomal signatures. We show that mitotic errors frequently involve multiple chromosome losses that are not biased toward maternal or paternal homologs. This outcome is characteristic of spindle abnormalities and chaotic cell division detected in previous studies. In contrast to meiotic errors, our data also show that mitotic errors are not significantly associated with maternal age. PGS patients referred due to previous IVF failure had elevated rates of mitotic error, while patients referred due to recurrent pregnancy loss had elevated rates of meiotic error, controlling for maternal age. These results support the conclusion that mitotic error is the predominant mechanism contributing to pregnancy losses occurring prior to blastocyst formation. This high-resolution view of the full spectrum of whole-chromosome abnormalities affecting early embryos provides insight

  15. Evidence of Selection against Complex Mitotic-Origin Aneuploidy during Preimplantation Development.

    Directory of Open Access Journals (Sweden)

    Rajiv C McCoy

    2015-10-01

    Full Text Available Whole-chromosome imbalances affect over half of early human embryos and are the leading cause of pregnancy loss. While these errors frequently arise in oocyte meiosis, many such whole-chromosome abnormalities affecting cleavage-stage embryos are the result of chromosome missegregation occurring during the initial mitotic cell divisions. The first wave of zygotic genome activation at the 4-8 cell stage results in the arrest of a large proportion of embryos, the vast majority of which contain whole-chromosome abnormalities. Thus, the full spectrum of meiotic and mitotic errors can only be detected by sampling after the initial cell divisions, but prior to this selective filter. Here, we apply 24-chromosome preimplantation genetic screening (PGS to 28,052 single-cell day-3 blastomere biopsies and 18,387 multi-cell day-5 trophectoderm biopsies from 6,366 in vitro fertilization (IVF cycles. We precisely characterize the rates and patterns of whole-chromosome abnormalities at each developmental stage and distinguish errors of meiotic and mitotic origin without embryo disaggregation, based on informative chromosomal signatures. We show that mitotic errors frequently involve multiple chromosome losses that are not biased toward maternal or paternal homologs. This outcome is characteristic of spindle abnormalities and chaotic cell division detected in previous studies. In contrast to meiotic errors, our data also show that mitotic errors are not significantly associated with maternal age. PGS patients referred due to previous IVF failure had elevated rates of mitotic error, while patients referred due to recurrent pregnancy loss had elevated rates of meiotic error, controlling for maternal age. These results support the conclusion that mitotic error is the predominant mechanism contributing to pregnancy losses occurring prior to blastocyst formation. This high-resolution view of the full spectrum of whole-chromosome abnormalities affecting early embryos

  16. Time-sequential observation of spindle and phragmoplast orientation in BY-2 cells with altered cortical actin microfilament patterning.

    Science.gov (United States)

    Kojo, Kei H; Yasuhara, Hiroki; Hasezawa, Seiichiro

    2014-06-18

    Precise division plane determination is essential for plant development. At metaphase, a dense actin microfilament meshwork appears on both sides of the cell center, forming a characteristic cortical actin microfilament twin peak pattern in BY-2 cells. We previously reported a strong correlation between altered cortical actin microfilament patterning and an oblique mitotic spindle orientation, implying that these actin microfilament twin peaks play a role in the regulation of mitotic spindle orientation. In the present study, time-sequential observation was used to reveal the progression from oblique phragmoplast to oblique cell plate orientation in cells with altered cortical actin microfilament patterning. In contrast to cells with normal actin microfilament twin peaks, oblique phragmoplast reorientation was rarely observed in cells with altered cortical actin microfilament patterning. These results support the important roles of cortical actin microfilament patterning in division plane orientation.

  17. BRCA1 Interaction of Centrosomal Protein Nlp Is Required for Successful Mitotic Progression*♦

    Science.gov (United States)

    Jin, Shunqian; Gao, Hua; Mazzacurati, Lucia; Wang, Yang; Fan, Wenhong; Chen, Qiang; Yu, Wei; Wang, Mingrong; Zhu, Xueliang; Zhang, Chuanmao; Zhan, Qimin

    2009-01-01

    Breast cancer susceptibility gene BRCA1 is implicated in the control of mitotic progression, although the underlying mechanism(s) remains to be further defined. Deficiency of BRCA1 function leads to disrupted mitotic machinery and genomic instability. Here, we show that BRCA1 physically interacts and colocalizes with Nlp, an important molecule involved in centrosome maturation and spindle formation. Interestingly, Nlp centrosomal localization and its protein stability are regulated by normal cellular BRCA1 function because cells containing BRCA1 mutations or silenced for endogenous BRCA1 exhibit disrupted Nlp colocalization to centrosomes and enhanced Nlp degradation. Its is likely that the BRCA1 regulation of Nlp stability involves Plk1 suppression. Inhibition of endogenous Nlp via the small interfering RNA approach results in aberrant spindle formation, aborted chromosomal segregation, and aneuploidy, which mimic the phenotypes of disrupted BRCA1. Thus, BRCA1 interaction of Nlp might be required for the successful mitotic progression, and abnormalities of Nlp lead to genomic instability. PMID:19509300

  18. Xenopus laevis Kif18A is a highly processive kinesin required for meiotic spindle integrity

    Directory of Open Access Journals (Sweden)

    Martin M. Möckel

    2017-04-01

    Full Text Available The assembly and functionality of the mitotic spindle depends on the coordinated activities of microtubule-associated motor proteins of the dynein and kinesin superfamily. Our current understanding of the function of motor proteins is significantly shaped by studies using Xenopus laevis egg extract as its open structure allows complex experimental manipulations hardly feasible in other model systems. Yet, the Kinesin-8 orthologue of human Kif18A has not been described in Xenopus laevis so far. Here, we report the cloning and characterization of Xenopus laevis (Xl Kif18A. Xenopus Kif18A is expressed during oocyte maturation and its depletion from meiotic egg extract results in severe spindle defects. These defects can be rescued by wild-type Kif18A, but not Kif18A lacking motor activity or the C-terminus. Single-molecule microscopy assays revealed that Xl_Kif18A possesses high processivity, which depends on an additional C-terminal microtubule-binding site. Human tissue culture cells depleted of endogenous Kif18A display mitotic defects, which can be rescued by wild-type, but not tail-less Xl_Kif18A. Thus, Xl_Kif18A is the functional orthologue of human Kif18A whose activity is essential for the correct function of meiotic spindles in Xenopus oocytes.

  19. NIMA-related kinase 1 (NEK1) regulates meiosis I spindle assembly by altering the balance between α-Adducin and Myosin X.

    Science.gov (United States)

    Brieño-Enríquez, Miguel A; Moak, Stefannie L; Holloway, J Kim; Cohen, Paula E

    2017-01-01

    NIMA-related kinase 1 (NEK1) is a serine/threonine and tyrosine kinase that is highly expressed in mammalian germ cells. Mutations in Nek1 induce anemia, polycystic kidney and infertility. In this study we evaluated the role of NEK1 in meiotic spindle formation in both male and female gametes. Our results show that the lack of NEK1 provokes an abnormal organization of the meiosis I spindle characterized by elongated and/or multipolar spindles, and abnormal chromosome congression. The aberrant spindle structure is concomitant with the disruption in localization and protein levels of myosin X (MYO10) and α-adducin (ADD1), both of which are implicated in the regulation of spindle formation during mitosis. Interaction of ADD1 with MYO10 is dependent on phosphorylation, whereby phosphorylation of ADD1 enables its binding to MYO10 on mitotic spindles. Reduction in ADD1 protein in NEK1 mutant mice is associated with hyperphosphorylation of ADD1, thereby preventing the interaction with MYO10 during meiotic spindle formation. Our results reveal a novel regulatory role for NEK1 in the regulation of spindle architecture and function during meiosis.

  20. Mitotic transcription and waves of gene reactivation during mitotic exit.

    Science.gov (United States)

    Palozola, Katherine C; Donahue, Greg; Liu, Hong; Grant, Gregory R; Becker, Justin S; Cote, Allison; Yu, Hongtao; Raj, Arjun; Zaret, Kenneth S

    2017-10-06

    Although the genome is generally thought to be transcriptionally silent during mitosis, technical limitations have prevented sensitive mapping of transcription during mitosis and mitotic exit. Thus, the means by which the interphase expression pattern is transduced to daughter cells have been unclear. We used 5-ethynyluridine to pulse-label transcripts during mitosis and mitotic exit and found that many genes exhibit transcription during mitosis, as confirmed with fluorescein isothiocyanate-uridine 5'-triphosphate labeling, RNA fluorescence in situ hybridization, and quantitative reverse transcription polymerase chain reaction. The first round of transcription immediately after mitosis primarily activates genes involved in the growth and rebuilding of daughter cells, rather than cell type-specific functions. We propose that the cell's transcription pattern is largely retained at a low level through mitosis, whereas the amplitude of transcription observed in interphase is reestablished during mitotic exit. Copyright © 2017 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works.

  1. Bipolar disorder

    Science.gov (United States)

    ... of pleasure in activities once enjoyed Loss of self-esteem Thoughts of death or suicide Trouble getting to ... other. This is called rapid cycling. Exams and Tests To diagnose bipolar disorder, the provider may do ...

  2. Bipolar disorder

    Directory of Open Access Journals (Sweden)

    F Colin

    2013-08-01

    Full Text Available Bipolar disorder (BD presents in different phases over time and is oftencomplicated by comorbid conditions such as substance-use disordersand anxiety disorders. Treatment usually involves pharmacotherapywith combinations of different classes of medications and frequentmedication revisions.

  3. SAPCD2 Controls Spindle Orientation and Asymmetric Divisions by Negatively Regulating the Gαi-LGN-NuMA Ternary Complex.

    Science.gov (United States)

    Chiu, Catherine W N; Monat, Carine; Robitaille, Mélanie; Lacomme, Marine; Daulat, Avais M; Macleod, Graham; McNeill, Helen; Cayouette, Michel; Angers, Stéphane

    2016-01-11

    Control of cell-division orientation is integral to epithelial morphogenesis and asymmetric cell division. Proper spatiotemporal localization of the evolutionarily conserved Gαi-LGN-NuMA protein complex is critical for mitotic spindle orientation, but how this is achieved remains unclear. Here we identify Suppressor APC domain containing 2 (SAPCD2) as a previously unreported LGN-interacting protein. We show that SAPCD2 is essential to instruct planar mitotic spindle orientation in both epithelial cell cultures and mouse retinal progenitor cells in vivo. Loss of SAPCD2 randomizes spindle orientation, which in turn disrupts cyst morphogenesis in three-dimensional cultures, and triples the number of terminal asymmetric cell divisions in the developing retina. Mechanistically, we show that SAPCD2 negatively regulates the localization of LGN at the cell cortex, likely by competing with NuMA for its binding. These results uncover SAPCD2 as a key regulator of the ternary complex controlling spindle orientation during morphogenesis and asymmetric cell divisions. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. MLL/WDR5 Complex Regulates Kif2A Localization to Ensure Chromosome Congression and Proper Spindle Assembly during Mitosis.

    Science.gov (United States)

    Ali, Aamir; Veeranki, Sailaja Naga; Chinchole, Akash; Tyagi, Shweta

    2017-06-19

    Mixed-lineage leukemia (MLL), along with multisubunit (WDR5, RbBP5, ASH2L, and DPY30) complex catalyzes the trimethylation of H3K4, leading to gene activation. Here, we characterize a chromatin-independent role for MLL during mitosis. MLL and WDR5 localize to the mitotic spindle apparatus, and loss of function of MLL complex by RNAi results in defects in chromosome congression and compromised spindle formation. We report interaction of MLL complex with several kinesin and dynein motors. We further show that the MLL complex associates with Kif2A, a member of the Kinesin-13 family of microtubule depolymerase, and regulates the spindle localization of Kif2A during mitosis. We have identified a conserved WDR5 interaction (Win) motif, so far unique to the MLL family, in Kif2A. The Win motif of Kif2A engages in direct interactions with WDR5 for its spindle localization. Our findings highlight a non-canonical mitotic function of MLL complex, which may have a direct impact on chromosomal stability, frequently compromised in cancer. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Mitotic bookmarking: maintaining post-mitotic reprogramming of transcription reactivation.

    Science.gov (United States)

    Lodhi, Niraj; Ji, Yingbiao; Tulin, Alexei

    2016-03-01

    Restoring chromatin structure with high fidelity after mitosis is critical for cell survival. Transcriptional reactivation of genes is the first step toward establishing identity of the daughter cell. During mitosis, chromatin bookmarking factors associated with specific chromatin regions ensure the restoration of the original gene expression pattern in daughter cells. Recent findings have provided new insights into the mechanisms, regulation, and biological significance of gene bookmarking in eukaryotes. In this review, we discuss how epigenetic factors, such as Poly(ADP-ribose) Polymerase-1, establish epigenetic memory in mitotic chromatin.

  6. Loss of the canonical spindle orientation function in the Pins/LGN homolog AGS3.

    Science.gov (United States)

    Saadaoui, Mehdi; Konno, Daijiro; Loulier, Karine; Goiame, Rosette; Jadhav, Vaibhav; Mapelli, Marina; Matsuzaki, Fumio; Morin, Xavier

    2017-09-01

    In many cell types, mitotic spindle orientation relies on the canonical "LGN complex" composed of Pins/LGN, Mud/NuMA, and Gα i subunits. Membrane localization of this complex recruits motor force generators that pull on astral microtubules to orient the spindle. Drosophila Pins shares highly conserved functional domains with its two vertebrate homologs LGN and AGS3. Whereas the role of Pins and LGN in oriented divisions is extensively documented, involvement of AGS3 remains controversial. Here, we show that AGS3 is not required for planar divisions of neural progenitors in the mouse neocortex. AGS3 is not recruited to the cell cortex and does not rescue LGN loss of function. Despite conserved interactions with NuMA and Gα i in vitro , comparison of LGN and AGS3 functional domains in vivo reveals unexpected differences in the ability of these interactions to mediate spindle orientation functions. Finally, we find that Drosophila Pins is unable to substitute for LGN loss of function in vertebrates, highlighting that species-specific modulations of the interactions between components of the Pins/LGN complex are crucial in vivo for spindle orientation. © 2017 The Authors.

  7. A tumor suppressor role of the Bub3 spindle checkpoint protein after apoptosis inhibition

    Science.gov (United States)

    Moutinho-Santos, Tatiana

    2013-01-01

    Most solid tumors contain aneuploid cells, indicating that the mitotic checkpoint is permissive to the proliferation of chromosomally aberrant cells. However, mutated or altered expression of mitotic checkpoint genes accounts for a minor proportion of human tumors. We describe a Drosophila melanogaster tumorigenesis model derived from knocking down spindle assembly checkpoint (SAC) genes and preventing apoptosis in wing imaginal discs. Bub3-deficient tumors that were also deficient in apoptosis displayed neoplastic growth, chromosomal aneuploidy, and high proliferative potential after transplantation into adult flies. Inducing aneuploidy by knocking down CENP-E and preventing apoptosis does not induce tumorigenesis, indicating that aneuploidy is not sufficient for hyperplasia. In this system, the aneuploidy caused by a deficient SAC is not driving tumorigenesis because preventing Bub3 from binding to the kinetochore does not cause hyperproliferation. Our data suggest that Bub3 has a nonkinetochore-dependent function that is consistent with its role as a tumor suppressor. PMID:23609535

  8. Costunolide causes mitotic arrest and enhances radiosensitivity in human hepatocellular carcinoma cells

    International Nuclear Information System (INIS)

    Liu, Chia-Yuan; Chang, Hsun-Shuo; Chen, Ih-Sheng; Chen, Chih-Jen; Hsu, Ming-Ling; Fu, Shu-Ling; Chen, Yu-Jen

    2011-01-01

    This work aimed to investigate the effect of costunolide, a sesquiterpene lactone isolated from Michelia compressa, on cell cycle distribution and radiosensitivity of human hepatocellular carcinoma (HCC) cells. The assessment used in this study included: cell viability assay, cell cycle analysis by DNA histogram, expression of phosphorylated histone H3 (Ser 10) by flow cytometer, mitotic index by Liu's stain and morphological observation, mitotic spindle alignment by immunofluorescence of alpha-tubulin, expression of cell cycle-related proteins by Western blotting, and radiation survival by clonogenic assay. Our results show that costunolide reduced the viability of HA22T/VGH cells. It caused a rapid G2/M arrest at 4 hours shown by DNA histogram. The increase in phosphorylated histone H3 (Ser 10)-positive cells and mitotic index indicates costunolide-treated cells are arrested at mitosis, not G2, phase. Immunofluorescence of alpha-tubulin for spindle formation further demonstrated these cells are halted at metaphase. Costunolide up-regulated the expression of phosphorylated Chk2 (Thr 68), phosphorylated Cdc25c (Ser 216), phosphorylated Cdk1 (Tyr 15) and cyclin B1 in HA22T/VGH cells. At optimal condition causing mitotic arrest, costunolide sensitized HA22T/VGH HCC cells to ionizing radiation with sensitizer enhancement ratio up to 1.9. Costunolide could reduce the viability and arrest cell cycling at mitosis in hepatoma cells. Logical exploration of this mitosis-arresting activity for cancer therapeutics shows costunolide enhanced the killing effect of radiotherapy against human HCC cells

  9. Msd1/SSX2IP-dependent microtubule anchorage ensures spindle orientation and primary cilia formation

    OpenAIRE

    Hori, Akiko; Ikebe, Chiho; Tada, Masazumi; Toda, Takashi

    2014-01-01

    Anchoring microtubules to the centrosome is critical for cell geometry and polarity, yet the molecular mechanism remains unknown. Here we show that the conserved human Msd1/SSX2IP is required for microtubule anchoring. hMsd1/SSX2IP is delivered to the centrosome in a centriolar satellite-dependent manner and binds the microtubule-nucleator ?-tubulin complex. hMsd1/SSX2IP depletion leads to disorganised interphase microtubules and misoriented mitotic spindles with reduced length and intensity....

  10. Cell biology of mitotic recombination

    DEFF Research Database (Denmark)

    Lisby, Michael; Rothstein, Rodney

    2015-01-01

    Homologous recombination provides high-fidelity DNA repair throughout all domains of life. Live cell fluorescence microscopy offers the opportunity to image individual recombination events in real time providing insight into the in vivo biochemistry of the involved proteins and DNA molecules...... as well as the cellular organization of the process of homologous recombination. Herein we review the cell biological aspects of mitotic homologous recombination with a focus on Saccharomyces cerevisiae and mammalian cells, but will also draw on findings from other experimental systems. Key topics...

  11. A Kinesin-Related Protein Required for the Mitotic Spindle Assembly

    Science.gov (United States)

    1999-05-01

    b. Equipment, etc. SW55.1 or SW50.1 rotor at 16°C in ultracentrifuge Two Pasteur pipettes with tips broken and fire polished to ~3 or 4-mm...coverslips with 1 /Ag/ml Hoechst in TBS-TX for 30 sec, mount in mounting medium, and seal with nail polish . Rinse top surface of coverslip with...the midzone. We have observed that KLP61F motors, phosphorylated at a cdkl/cyclin B consensus domain within the BimC box ( BCB ), localize along the

  12. Electro-Acoustic Behavior of the Mitotic Spindle: A Semi-Classical Coarse-Grained Model

    Czech Academy of Sciences Publication Activity Database

    Havelka, Daniel; Kučera, Ondřej; Deriu, M.A.; Cifra, Michal

    2014-01-01

    Roč. 9, č. 1 (2014), e86501 E-ISSN 1932-6203 R&D Projects: GA ČR(CZ) GAP102/11/0649 Institutional support: RVO:67985882 Keywords : electric fields * tubulin * chromosomes Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 3.234, year: 2014

  13. Bipolar Disorder (For Teens)

    Science.gov (United States)

    ... Staying Safe Videos for Educators Search English Español Bipolar Disorder KidsHealth / For Teens / Bipolar Disorder What's in this ... Disorder Print en español Trastorno bipolar What Is Bipolar Disorder? Bipolar disorders are one of several medical conditions ...

  14. Neutrality in bipolar structures

    DEFF Research Database (Denmark)

    Montero, Javier; Rodríguez, J. Tinguaro; Franco, Camilo

    2014-01-01

    In this paper, we want to stress that bipolar knowledge representation naturally allows a family of middle states which define as a consequence different kinds of bipolar structures. These bipolar structures are deeply related to the three types of bipolarity introduced by Dubois and Prade, but our...... approach offers a systematic explanation of how such bipolar structures appear and can be identified....

  15. Regulation of mitosis by the NIMA kinase involves TINA and its newly discovered partner, An-WDR8, at spindle pole bodies

    Science.gov (United States)

    Shen, Kuo-Fang; Osmani, Stephen A.

    2013-01-01

    The NIMA kinase is required for mitotic nuclear pore complex disassembly and potentially controls other mitotic-specific events. To investigate this possibility, we imaged NIMA–green fluorescent protein (GFP) using four-dimensional spinning disk confocal microscopy. At mitosis NIMA-GFP locates to spindle pole bodies (SPBs), which contain Cdk1/cyclin B, followed by Aurora, TINA, and the BimC kinesin. NIMA promotes NPC disassembly in a spatially regulated manner starting near SPBs. NIMA is also required for TINA, a NIMA-interacting protein, to locate to SPBs during initiation of mitosis, and TINA is then necessary for locating NIMA back to SPBs during mitotic progression. To help expand the NIMA-TINA pathway, we affinity purified TINA and found it to uniquely copurify with An-WDR8, a WD40-domain protein conserved from humans to plants. Like TINA, An-WDR8 accumulates within nuclei during G2 but disperses from nuclei before locating to mitotic SPBs. Without An-WDR8, TINA levels are greatly reduced, whereas TINA is necessary for mitotic targeting of An-WDR8. Finally, we show that TINA is required to anchor mitotic microtubules to SPBs and, in combination with An-WDR8, for successful mitosis. The findings provide new insights into SPB targeting and indicate that the mitotic microtubule-anchoring system at SPBs involves WDR8 in complex with TINA. PMID:24152731

  16. The functionally elusive RabI chromosome configuration directly regulates nuclear membrane remodeling at mitotic onset.

    Science.gov (United States)

    Fernández-Álvarez, Alfonso; Cooper, Julia Promisel

    2017-08-03

    Despite its ubiquity in interphase eukaryotic nuclei, the functional significance of the RabI configuration, in which interphase centromeres are clustered at the nuclear envelope (NE) near the centrosome and telomeres localize at the opposite end of the nucleus, has remained mysterious. In a broad variety of organisms, including Schizosaccharomyces pombe, the RabI configuration is maintained throughout mitotic interphase. The fission yeast linker of nucleoskeleton and cytoskeleton (LINC) complex mediates this centromere association. The functional significance of centromere positioning during interphase has been recently revealed using a conditionally inactivated LINC allele that maintains LINC stability but releases interphase centromere-LINC contacts. Remarkably, this interphase release abolishes mitotic spindle formation. Here, we confirm these observations using an alternative strategy to explore the role of centromere-NE association without modifying the LINC complex. We analyze spindle dynamics in cells lacking Csi1, a stabilizer of centromere-LINC associations, and Lem2, a NE protein harboring lamin interacting domains. We recapitulate these observations and their implications for the functional significance of centromere positioning for cell cycle progression in fission yeast and most likely, a wide range of eukaryotes.

  17. The role of centrosomal Nlp in the control of mitotic progression and tumourigenesis.

    Science.gov (United States)

    Li, J; Zhan, Q

    2011-05-10

    The human centrosomal ninein-like protein (Nlp) is a new member of the γ-tubulin complexes binding proteins (GTBPs) that is essential for proper execution of various mitotic events. The primary function of Nlp is to promote microtubule nucleation that contributes to centrosome maturation, spindle formation and chromosome segregation. Its subcellular localisation and protein stability are regulated by several crucial mitotic kinases, such as Plk1, Nek2, Cdc2 and Aurora B. Several lines of evidence have linked Nlp to human cancer. Deregulation of Nlp in cell models results in aberrant spindle, chromosomal missegregation and multinulei, and induces chromosomal instability and renders cells tumourigenic. Overexpression of Nlp induces anchorage-independent growth and immortalised primary cell transformation. In addition, we first demonstrate that the expression of Nlp is elevated primarily due to NLP gene amplification in human breast cancer and lung carcinoma. Consistently, transgenic mice overexpressing Nlp display spontaneous tumours in breast, ovary and testicle, and show rapid onset of radiation-induced lymphoma, indicating that Nlp is involved in tumourigenesis. This review summarises our current knowledge of physiological roles of Nlp, with an emphasis on its potentials in tumourigenesis.

  18. What is Bipolar Disorder?

    Science.gov (United States)

    ... affect friends and family? For More Information Share Bipolar Disorder Download PDF Download ePub Order a free hardcopy ... brochure will give you more information. What is bipolar disorder? Bipolar disorder is a serious brain illness. It ...

  19. Sleep spindle density in narcolepsy

    DEFF Research Database (Denmark)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Hvidtfelt, Mathias

    2017-01-01

    BACKGROUND: Patients with narcolepsy type 1 (NT1) show alterations in sleep stage transitions, rapid-eye-movement (REM) and non-REM sleep due to the loss of hypocretinergic signaling. However, the sleep microstructure has not yet been evaluated in these patients. We aimed to evaluate whether...... the sleep spindle (SS) density is altered in patients with NT1 compared to controls and patients with narcolepsy type 2 (NT2). METHODS: All-night polysomnographic recordings from 28 NT1 patients, 19 NT2 patients, 20 controls (C) with narcolepsy-like symptoms, but with normal cerebrospinal fluid hypocretin...... levels and multiple sleep latency tests, and 18 healthy controls (HC) were included. Unspecified, slow, and fast SS were automatically detected, and SS densities were defined as number per minute and were computed across sleep stages and sleep cycles. The between-cycle trends of SS densities in N2...

  20. Phosphorylation of CPAP by Aurora-A Maintains Spindle Pole Integrity during Mitosis.

    Science.gov (United States)

    Chou, En-Ju; Hung, Liang-Yi; Tang, Chieh-Ju C; Hsu, Wen-Bin; Wu, Hsin-Yi; Liao, Pao-Chi; Tang, Tang K

    2016-03-29

    CPAP is required for centriole elongation during S/G2 phase, but the role of CPAP in mitosis is incompletely understood. Here, we show that CPAP maintains spindle pole integrity through its phosphorylation by Aurora-A during mitosis. Depletion of CPAP induced a prolonged delay in mitosis, pericentriolar material (PCM) dispersion, and multiple mitotic abnormalities. Further studies demonstrated that CPAP directly interacts with and is phosphorylated by Aurora-A at serine 467 during mitosis. Interestingly, the dispersal of the PCM was effectively rescued by ectopic expression of wild-type CPAP or a phospho-mimic CPAP-S467D mutant, but not a non-phosphorylated CPAP-S467A mutant. Finally, we found that CPAP-S467D has a low affinity for microtubule binding but a high affinity for PCM proteins. Together, our results support a model wherein CPAP is required for proper mitotic progression, and phosphorylation of CPAP by Aurora-A is essential for maintaining spindle pole integrity. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights reserved.

  1. Mto2 multisite phosphorylation inactivates non-spindle microtubule nucleation complexes during mitosis

    Science.gov (United States)

    Borek, Weronika E.; Groocock, Lynda M.; Samejima, Itaru; Zou, Juan; de Lima Alves, Flavia; Rappsilber, Juri; Sawin, Kenneth E.

    2015-01-01

    Microtubule nucleation is highly regulated during the eukaryotic cell cycle, but the underlying molecular mechanisms are largely unknown. During mitosis in fission yeast Schizosaccharomyces pombe, cytoplasmic microtubule nucleation ceases simultaneously with intranuclear mitotic spindle assembly. Cytoplasmic nucleation depends on the Mto1/2 complex, which binds and activates the γ-tubulin complex and also recruits the γ-tubulin complex to both centrosomal (spindle pole body) and non-centrosomal sites. Here we show that the Mto1/2 complex disassembles during mitosis, coincident with hyperphosphorylation of Mto2 protein. By mapping and mutating multiple Mto2 phosphorylation sites, we generate mto2-phosphomutant strains with enhanced Mto1/2 complex stability, interaction with the γ-tubulin complex and microtubule nucleation activity. A mutant with 24 phosphorylation sites mutated to alanine, mto2[24A], retains interphase-like behaviour even in mitotic cells. This provides a molecular-level understanding of how phosphorylation ‘switches off' microtubule nucleation complexes during the cell cycle and, more broadly, illuminates mechanisms regulating non-centrosomal microtubule nucleation. PMID:26243668

  2. Transtorno bipolar

    Directory of Open Access Journals (Sweden)

    Alda Martin

    1999-01-01

    Full Text Available Os resultados de estudos de famílias sugerem que o transtorno bipolar tenha uma base genética. Essa hipótese foi reforçada em estudos de adoção e de gêmeos. A herança do transtorno bipolar é complexa, envolve vários genes, além de apresentar heterogeneidade e interação entre fatores genéticos e não-genéticos. Achados, que já foram replicados, já implicaram os cromossomos 4, 12, 18 e 21, entre outros, na busca por genes de suscetibilidade. Os resultados mais promissores foram obtidos através de estudos de ligação. Por outro lado, os estudos de associação geraram dados interessantes, mas ainda vagos. Os estudos de populações de pacientes homogêneos e a melhor definição do fenótipo deverão contribuir para avanços futuros. A identificação dos genes relacionados ao transtorno bipolar irá permitir o melhor entendimento e tratamento dessa doença.

  3. Plk1 inhibition causes post-mitotic DNA damage and senescence in a range of human tumor cell lines.

    Directory of Open Access Journals (Sweden)

    Denise L Driscoll

    Full Text Available Plk1 is a checkpoint protein whose role spans all of mitosis and includes DNA repair, and is highly conserved in eukaryotes from yeast to man. Consistent with this wide array of functions for Plk1, the cellular consequences of Plk1 disruption are diverse, spanning delays in mitotic entry, mitotic spindle abnormalities, and transient mitotic arrest leading to mitotic slippage and failures in cytokinesis. In this work, we present the in vitro and in vivo consequences of Plk1 inhibition in cancer cells using potent, selective small-molecule Plk1 inhibitors and Plk1 genetic knock-down approaches. We demonstrate for the first time that cellular senescence is the predominant outcome of Plk1 inhibition in some cancer cell lines, whereas in other cancer cell lines the dominant outcome appears to be apoptosis, as has been reported in the literature. We also demonstrate strong induction of DNA double-strand breaks in all six lines examined (as assayed by γH2AX, which occurs either during mitotic arrest or mitotic-exit, and may be linked to the downstream induction of senescence. Taken together, our findings expand the view of Plk1 inhibition, demonstrating the occurrence of a non-apoptotic outcome in some settings. Our findings are also consistent with the possibility that mitotic arrest observed as a result of Plk1 inhibition is at least partially due to the presence of unrepaired double-strand breaks in mitosis. These novel findings may lead to alternative strategies for the development of novel therapeutic agents targeting Plk1, in the selection of biomarkers, patient populations, combination partners and dosing regimens.

  4. Change of mitotic behavior and ultra structure of 'Fuju' (Citrus reticulata Blanco) stem-apex clones after space flight

    International Nuclear Information System (INIS)

    Wu Rujian; Huang Jinghao; Wen Shouxing; Cai Zijian; Luo Tuyan; Chen Liangfeng; Wang Zhouwen

    2011-01-01

    By using conventional squash stain technique and ultrathin sectioning technique, the effects of space flight on mitotic behavior and ultrastructure were studied in the shoot apical meristem of 'Fuju' (Citrus reticulata Blanco), which had been carried by China's seed-breeding satellite, Shijian-8. The results showed that space flight had effect on the mutagenesis of stem-apical meristem. Abnormal mitosis with various degrees had been detected in 13 mutant clones, of which mitotic aberrations in clone '08004' were significantly higher than the others. The aberration rate of numerical abnormalities of chromosomes at metaphase, lagging chromosome, micronucleus, C-spindle, S-spindle and polyarch spindle in the clone '08004' was 0.34%, 0.669%, 0.86%, 0.17%, 1.20% and 1.03%, respectively. The ultrastructure of mesophyll cell in most clones was unchanged, but nucleus chromatin agglutination, chloroplast thylakoid disintegrated, autophagosome appeared, cell vacuolated, plasmolysis and the formation of apoptotic body were found in the clone '08004', suggesting that programmed cell death (PCD) Nevertheless, no change in the mitochondrial structure was observed until terminal phase of PCD. (authors)

  5. 2-(3-Methoxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (HKL-1) induces G2/M arrest and mitotic catastrophe in human leukemia HL-60 cells

    Energy Technology Data Exchange (ETDEWEB)

    Hsu, Mei-Hua; Liu, Chin-Yu; Lin, Chiao-Min; Chen, Yen-Jung; Chen, Chun-Jen; Lin, Yu-Fu; Huang, Li-Jiau [Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan, ROC (China); Lee, Kuo-Hsiung [Natural Products Research Laboratories, Eshelman School of Pharmacy, University of North Carolina, Chapel Hill, NC 27599 (United States); Chinese Medicine Research and Development Center, China Medical University and Hospital, Taichung, Taiwan, ROC (China); Kuo, Sheng-Chu, E-mail: sckuo@mail.cmu.edu.tw [Graduate Institute of Pharmaceutical Chemistry, China Medical University, Taichung, Taiwan, ROC (China)

    2012-03-01

    2-(3-Methoxyphenyl)-5-methyl-1,8-naphthyridin-4(1H)-one (HKL-1), a 2-phenyl-1,8-naphthyridin-4-one (2-PN) derivative, was synthesized and evaluated as an effective antimitotic agent in our laboratory. However, the molecular mechanisms are uncertain. In this study, HKL-1 was demonstrated to induce multipolar spindles, sustain mitotic arrest and generate multinucleated cells, all of which indicate mitotic catastrophe, in human leukemia HL-60 cells. Western blotting showed that HKL-1 induces mitotic catastrophe in HL-60 cells through regulating mitotic phase-specific kinases (down-regulating CDK1, cyclin B1, CENP-E, and aurora B) and regulating the expression of Bcl-2 family proteins (down-regulating Bcl-2 and up-regulating Bax and Bak), followed by caspase-9/-3 cleavage. These findings suggest that HKL-1 appears to exert its cytotoxicity toward HL-60 cells in culture by inducing mitotic catastrophe. Highlights: ► HKL-1 is a potential antimitotic agent against HL-60 cells. ► HKL-1 induces spindle disruption and sustained resulted in mitotic catastrophe. ► CENP-E and aurora B protein expressions significantly reduced. ► Bcl-2 family protein expressions altered and caspase-9/-3 activation. ► HKL-1 is an attractive candidate for possible use as a novel antimitotic agent.

  6. Desmoplastic spindle cell thymomas: a clinicopathologic and immunohistochemical study of 14 cases.

    Science.gov (United States)

    Weissferdt, Annikka; Moran, Cesar A

    2013-04-01

    Fourteen cases of spindle cell thymoma with prominent desmoplastic changes are presented. The patients are 9 women and 5 men between the ages of 46 and 79 years. Clinically, the patients presented with symptoms of chest pain, shortness of breath, and dyspnea. Radiographic imaging showed the presence of an anterior mediastinal mass, and surgical resection of the tumor mass was accomplished in all of the cases. Grossly, all the tumors were described as ovoid tumor masses measuring between 4 and 9 cm in greatest dimension. At cut surface, the tumors were described as solid and light tan-brown in color. Necrosis and hemorrhage were not recorded in any of the cases. Histologically, 8 cases were invasive, and 6 were encapsulated tumors. Extensive areas of young fibrocollagen and a prominent fibroblastic proliferation characterized the tumors. Scattered areas of more conventional spindle cell thymoma were present in all cases but mitotic activity, necrosis, and/or hemorrhage were not identified. Immunohistochemical stains were performed in 9 cases, showing tumor cells positive for pancytokeratin, cytokeratin 5/6, Bcl-2, Pax8, and vimentin. Clinical follow-up in 8 patients showed that all are alive and well 1 to 8 years after diagnosis. The current growth pattern of spindle cell thymomas is unusual and should be kept in mind when evaluating mediastinoscopic biopsies. Copyright © 2013 Elsevier Inc. All rights reserved.

  7. Kalanchoe tubiflora extract inhibits cell proliferation by affecting the mitotic apparatus.

    Science.gov (United States)

    Hsieh, Yi-Jen; Yang, Ming-Yeh; Leu, Yann-Lii; Chen, Chinpiao; Wan, Chin-Fung; Chang, Meng-Ya; Chang, Chih-Jui

    2012-09-10

    Kalanchoe tubiflora (KT) is a succulent plant native to Madagascar, and is commonly used as a medicinal agent in Southern Brazil. The underlying mechanisms of tumor suppression are largely unexplored. Cell viability and wound-healing were analyzed by MTT assay and scratch assay respectively. Cell cycle profiles were analyzed by FACS. Mitotic defects were analyzed by indirect immunofluoresence images. An n-Butanol-soluble fraction of KT (KT-NB) was able to inhibit cell proliferation. After a 48 h treatment with 6.75 μg/ml of KT, the cell viability was less than 50% of controls, and was further reduced to less than 10% at higher concentrations. KT-NB also induced an accumulation of cells in the G2/M phase of the cell cycle as well as an increased level of cells in the subG1 phase. Instead of disrupting the microtubule network of interphase cells, KT-NB reduced cell viability by inducing multipolar spindles and defects in chromosome alignment. KT-NB inhibits cell proliferation and reduces cell viability by two mechanisms that are exclusively involved with cell division: first by inducing multipolarity; second by disrupting chromosome alignment during metaphase. KT-NB reduced cell viability by exclusively affecting formation of the proper structure of the mitotic apparatus. This is the main idea of the new generation of anti-mitotic agents. All together, KT-NB has sufficient potential to warrant further investigation as a potential new anticancer agent candidate.

  8. Bipolar disorder: an overview

    African Journals Online (AJOL)

    which is the reason that up to 69% of patients with BD are misdiagnosed.1 Bipolar ... Cyclothymic disorder. • Substance/medication induced bipolar and related disorder. • Bipolar and related disorder due to another medical condition ... patients. Keywords: bipolar disorder, mania, depression, pharmacological management.

  9. p600 regulates spindle orientation in apical neural progenitors and contributes to neurogenesis in the developing neocortex

    Directory of Open Access Journals (Sweden)

    Camille Belzil

    2014-05-01

    Full Text Available Apical neural progenitors (aNPs drive neurogenesis by means of a program consisting of self-proliferative and neurogenic divisions. The balance between these two manners of division sustains the pool of apical progenitors into late neurogenesis, thereby ensuring their availability to populate the brain with terminal cell types. Using knockout and in utero electroporation mouse models, we report a key role for the microtubule-associated protein 600 (p600 in the regulation of spindle orientation in aNPs, a cellular event that has been associated with cell fate and neurogenesis. We find that p600 interacts directly with the neurogenic protein Ndel1 and that aNPs knockout for p600, depleted of p600 by shRNA or expressing a Ndel1-binding p600 fragment all display randomized spindle orientation. Depletion of p600 by shRNA or expression of the Ndel1-binding p600 fragment also results in a decreased number of Pax6-positive aNPs and an increased number of Tbr2-positive basal progenitors destined to become neurons. These Pax6-positive aNPs display a tilted mitotic spindle. In mice wherein p600 is ablated in progenitors, the production of neurons is significantly impaired and this defect is associated with microcephaly. We propose a working model in which p600 controls spindle orientation in aNPs and discuss its implication for neurogenesis.

  10. The Drosophila orthologue of the INT6 onco-protein regulates mitotic microtubule growth and kinetochore structure.

    Directory of Open Access Journals (Sweden)

    Fioranna Renda

    2017-05-01

    Full Text Available INT6/eIF3e is a highly conserved component of the translation initiation complex that interacts with both the 26S proteasome and the COP9 signalosome, two complexes implicated in ubiquitin-mediated protein degradation. The INT6 gene was originally identified as the insertion site of the mouse mammary tumor virus (MMTV, and later shown to be involved in human tumorigenesis. Here we show that depletion of the Drosophila orthologue of INT6 (Int6 results in short mitotic spindles and deformed centromeres and kinetochores with low intra-kinetochore distance. Poleward flux of microtubule subunits during metaphase is reduced, although fluorescence recovery after photobleaching (FRAP demonstrates that microtubules remain dynamic both near the kinetochores and at spindle poles. Mitotic progression is delayed during metaphase due to the activity of the spindle assembly checkpoint (SAC. Interestingly, a deubiquitinated form of the kinesin Klp67A (a putative orthologue of human Kif18A accumulates near the kinetochores in Int6-depleted cells. Consistent with this finding, Klp67A overexpression mimics the Int6 RNAi phenotype. Furthermore, simultaneous depletion of Int6 and Klp67A results in a phenotype identical to RNAi of just Klp67A, which indicates that Klp67A deficiency is epistatic over Int6 deficiency. We propose that Int6-mediated ubiquitination is required to control the activity of Klp67A. In the absence of this control, excess of Klp67A at the kinetochore suppresses microtubule plus-end polymerization, which in turn results in reduced microtubule flux, spindle shortening, and centromere/kinetochore deformation.

  11. Bub3 is a spindle assembly checkpoint protein regulating chromosome segregation during mouse oocyte meiosis.

    Directory of Open Access Journals (Sweden)

    Mo Li

    Full Text Available In mitosis, the spindle assembly checkpoint (SAC prevents anaphase onset until all chromosomes have been attached to the spindle microtubules and aligned correctly at the equatorial metaphase plate. The major checkpoint proteins in mitosis consist of mitotic arrest-deficient (Mad1-3, budding uninhibited by benzimidazole (Bub1, Bub3, and monopolar spindle 1(Mps1. During meiosis, for the formation of a haploid gamete, two consecutive rounds of chromosome segregation occur with only one round of DNA replication. To pull homologous chromosomes to opposite spindle poles during meiosis I, both sister kinetochores of a homologue must face toward the same pole which is very different from mitosis and meiosis II. As a core member of checkpoint proteins, the individual role of Bub3 in mammalian oocyte meiosis is unclear. In this study, using overexpression and RNA interference (RNAi approaches, we analyzed the role of Bub3 in mouse oocyte meiosis. Our data showed that overexpressed Bub3 inhibited meiotic metaphase-anaphase transition by preventing homologous chromosome and sister chromatid segregations in meiosis I and II, respectively. Misaligned chromosomes, abnormal polar body and double polar bodies were observed in Bub3 knock-down oocytes, causing aneuploidy. Furthermore, through cold treatment combined with Bub3 overexpression, we found that overexpressed Bub3 affected the attachments of microtubules and kinetochores during metaphase-anaphase transition. We propose that as a member of SAC, Bub3 is required for regulation of both meiosis I and II, and is potentially involved in kinetochore-microtubule attachment in mammalian oocytes.

  12. Cyclin K dependent regulation of Aurora B affects apoptosis and proliferation by induction of mitotic catastrophe in prostate cancer.

    Science.gov (United States)

    Schecher, Sabrina; Walter, Britta; Falkenstein, Michael; Macher-Goeppinger, Stephan; Stenzel, Philipp; Krümpelmann, Kristina; Hadaschik, Boris; Perner, Sven; Kristiansen, Glen; Duensing, Stefan; Roth, Wilfried; Tagscherer, Katrin E

    2017-10-15

    Cyclin K plays a critical role in transcriptional regulation as well as cell development. However, the role of Cyclin K in prostate cancer is unknown. Here, we describe the impact of Cyclin K on prostate cancer cells and examine the clinical relevance of Cyclin K as a biomarker for patients with prostate cancer. We show that Cyclin K depletion in prostate cancer cells induces apoptosis and inhibits proliferation accompanied by an accumulation of cells in the G2/M phase. Moreover, knockdown of Cyclin K causes mitotic catastrophe displayed by multinucleation and spindle multipolarity. Furthermore, we demonstrate a Cyclin K dependent regulation of the mitotic kinase Aurora B and provide evidence for an Aurora B dependent induction of mitotic catastrophe. In addition, we show that Cyclin K expression is associated with poor biochemical recurrence-free survival in patients with prostate cancer treated with an adjuvant therapy. In conclusion, targeting Cyclin K represents a novel, promising anti-cancer strategy to induce cell cycle arrest and apoptotic cell death through induction of mitotic catastrophe in prostate cancer cells. Moreover, our results indicate that Cyclin K is a putative predictive biomarker for clinical outcome and therapy response for patients with prostate cancer. © 2017 UICC.

  13. Reduced sleep spindles and spindle coherence in schizophrenia: mechanisms of impaired memory consolidation?

    Science.gov (United States)

    Wamsley, Erin J; Tucker, Matthew A; Shinn, Ann K; Ono, Kim E; McKinley, Sophia K; Ely, Alice V; Goff, Donald C; Stickgold, Robert; Manoach, Dara S

    2012-01-15

    Sleep spindles are thought to induce synaptic changes and thereby contribute to memory consolidation during sleep. Patients with schizophrenia show dramatic reductions of both spindles and sleep-dependent memory consolidation, which may be causally related. To examine the relations of sleep spindle activity to sleep-dependent consolidation of motor procedural memory, 21 chronic, medicated schizophrenia outpatients and 17 healthy volunteers underwent polysomnography on two consecutive nights. On the second night, participants were trained on the finger-tapping motor sequence task (MST) at bedtime and tested the following morning. The number, density, frequency, duration, amplitude, spectral content, and coherence of stage 2 sleep spindles were compared between groups and examined in relation to overnight changes in MST performance. Patients failed to show overnight improvement on the MST and differed significantly from control participants who did improve. Patients also exhibited marked reductions in the density (reduced 38% relative to control participants), number (reduced 36%), and coherence (reduced 19%) of sleep spindles but showed no abnormalities in the morphology of individual spindles or of sleep architecture. In patients, reduced spindle number and density predicted less overnight improvement on the MST. In addition, reduced amplitude and sigma power of individual spindles correlated with greater severity of positive symptoms. The observed sleep spindle abnormalities implicate thalamocortical network dysfunction in schizophrenia. In addition, the findings suggest that abnormal spindle generation impairs sleep-dependent memory consolidation in schizophrenia, contributes to positive symptoms, and is a promising novel target for the treatment of cognitive deficits in schizophrenia. Copyright © 2012 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

  14. Bipolar Items

    Directory of Open Access Journals (Sweden)

    Nishiguchi Sumiyo

    2016-12-01

    Full Text Available This article asserts that the Japanese wide-scope mo ‘even’ in simple sentences are bipolar items (BPIs antilicensed or forbidden by negation and licensed in a non-monotonic (NM environment. BPIs share the features of negative polarity items (NPIs as well as positive polarity items (PPIs. The Dutch ooit ‘ever’, the Serbo-Croatian i-series ‘and/even’, and the Hungarian is-series ‘and/even’ are antilicensed by clausemate negation and licensed by extraclausal negation (van der Wouden, 1997; Progovac, 1994; Szabolcsi, 2002 or non-monotonic negative (and positive, for Serbo-Croatian emotive predicates. Adding an NPI rescues BPIs in uncomfortable clausemate negation.

  15. Cdc14 Early Anaphase Release, FEAR, Is Limited to the Nucleus and Dispensable for Efficient Mitotic Exit.

    Directory of Open Access Journals (Sweden)

    Christopher M Yellman

    Full Text Available Cdc14 phosphatase is a key regulator of exit from mitosis, acting primarily through antagonism of cyclin-dependent kinase, and is also thought to be important for meiosis. Cdc14 is released from its sequestration site in the nucleolus in two stages, first by the non-essential Cdc Fourteen Early Anaphase Release (FEAR pathway and later by the essential Mitotic Exit Network (MEN, which drives efficient export of Cdc14 to the cytoplasm. We find that Cdc14 is confined to the nucleus during early mitotic anaphase release, and during its meiosis I release. Proteins whose degradation is directed by Cdc14 as a requirement for mitotic exit (e.g. the B-type cyclin, Clb2, remain stable during mitotic FEAR, a result consistent with Cdc14 being restricted to the nucleus and not participating directly in mitotic exit. Cdc14 released by the FEAR pathway has been proposed to have a wide variety of activities, all of which are thought to promote passage through anaphase. Proposed functions of FEAR include stabilization of anaphase spindles, resolution of the rDNA to allow its segregation, and priming of the MEN so that mitotic exit can occur promptly and efficiently. We tested the model for FEAR functions using the FEAR-deficient mutation net1-6cdk. Our cytological observations indicate that, contrary to the current model, FEAR is fully dispensable for timely progression through a series of anaphase landmarks and mitotic exit, although it is required for timely rDNA segregation. The net1-6cdk mutation suppresses temperature-sensitive mutations in MEN genes, suggesting that rather than activating mitotic exit, FEAR either inhibits the MEN or has no direct effect upon it. One interpretation of this result is that FEAR delays MEN activation to ensure that rDNA segregation occurs before mitotic exit. Our findings clarify the distinction between FEAR and MEN-dependent Cdc14 activities and will help guide emerging quantitative models of this cell cycle transition.

  16. A defect-driven diagnostic method for machine tool spindles.

    Science.gov (United States)

    Vogl, Gregory W; Donmez, M Alkan

    2015-01-01

    Simple vibration-based metrics are, in many cases, insufficient to diagnose machine tool spindle condition. These metrics couple defect-based motion with spindle dynamics; diagnostics should be defect-driven. A new method and spindle condition estimation device (SCED) were developed to acquire data and to separate system dynamics from defect geometry. Based on this method, a spindle condition metric relying only on defect geometry is proposed. Application of the SCED on various milling and turning spindles shows that the new approach is robust for diagnosing the machine tool spindle condition.

  17. Sleep Spindles as Facilitators of Memory Formation and Learning.

    Science.gov (United States)

    Ulrich, Daniel

    2016-01-01

    Over the past decades important progress has been made in understanding the mechanisms of sleep spindle generation. At the same time a physiological role of sleep spindles is starting to be revealed. Behavioural studies in humans and animals have found significant correlations between the recall performance in different learning tasks and the amount of sleep spindles in the intervening sleep. Concomitant neurophysiological experiments showed a close relationship between sleep spindles and other sleep related EEG rhythms as well as a relationship between sleep spindles and synaptic plasticity. Together, there is growing evidence from several disciplines in neuroscience for a participation of sleep spindles in memory formation and learning.

  18. Sleep Spindles as Facilitators of Memory Formation and Learning

    Directory of Open Access Journals (Sweden)

    Daniel Ulrich

    2016-01-01

    Full Text Available Over the past decades important progress has been made in understanding the mechanisms of sleep spindle generation. At the same time a physiological role of sleep spindles is starting to be revealed. Behavioural studies in humans and animals have found significant correlations between the recall performance in different learning tasks and the amount of sleep spindles in the intervening sleep. Concomitant neurophysiological experiments showed a close relationship between sleep spindles and other sleep related EEG rhythms as well as a relationship between sleep spindles and synaptic plasticity. Together, there is growing evidence from several disciplines in neuroscience for a participation of sleep spindles in memory formation and learning.

  19. Muscle spindle and fusimotor activity in locomotion.

    Science.gov (United States)

    Ellaway, Peter H; Taylor, Anthony; Durbaba, Rade

    2015-08-01

    Mammals may exhibit different forms of locomotion even within a species. A particular form of locomotion (e.g. walk, run, bound) appears to be selected by supraspinal commands, but the precise pattern, i.e. phasing of limbs and muscles, is generated within the spinal cord by so-called central pattern generators. Peripheral sense organs, particularly the muscle spindle, play a crucial role in modulating the central pattern generator output. In turn, the feedback from muscle spindles is itself modulated by static and dynamic fusimotor (gamma) neurons. The activity of muscle spindle afferents and fusimotor neurons during locomotion in the cat is reviewed here. There is evidence for some alpha-gamma co-activation during locomotion involving static gamma motoneurons. However, both static and dynamic gamma motoneurons show patterns of modulation that are distinct from alpha motoneuron activity. It has been proposed that static gamma activity may drive muscle spindle secondary endings to signal the intended movement to the central nervous system. Dynamic gamma motoneuron drive appears to prime muscle spindle primary endings to signal transitions in phase of the locomotor cycle. These findings come largely from reduced animal preparations (decerebrate) and require confirmation in freely moving intact animals. © 2015 Anatomical Society.

  20. Mitotic bookmarking in development and stem cells.

    Science.gov (United States)

    Festuccia, Nicola; Gonzalez, Inma; Owens, Nick; Navarro, Pablo

    2017-10-15

    The changes imposed on the nucleus, chromatin and its regulators during mitosis lead to the dismantlement of most gene regulatory processes. However, an increasing number of transcriptional regulators are being identified as capable of binding their genomic targets during mitosis. These so-called 'mitotic bookmarking factors' encompass transcription factors and chromatin modifiers that are believed to convey gene regulatory information from mother to daughter cells. In this Primer, we review mitotic bookmarking processes in development and stem cells and discuss the interest and potential importance of this concept with regard to epigenetic regulation and cell fate transitions involving cellular proliferation. © 2017. Published by The Company of Biologists Ltd.

  1. Cug2 is essential for normal mitotic control and CNS development in zebrafish

    Directory of Open Access Journals (Sweden)

    Kim Nam-Soon

    2011-08-01

    Full Text Available Abstract Background We recently identified a novel oncogene, Cancer-upregulated gene 2 (CUG2, which is essential for kinetochore formation and promotes tumorigenesis in mammalian cells. However, the in vivo function of CUG2 has not been studied in animal models. Results To study the function of CUG2 in vivo, we isolated a zebrafish homologue that is expressed specifically in the proliferating cells of the central nervous system (CNS. Morpholino-mediated knockdown of cug2 resulted in apoptosis throughout the CNS and the development of neurodegenerative phenotypes. In addition, cug2-deficient embryos contained mitotically arrested cells displaying abnormal spindle formation and chromosome misalignment in the neural plate. Conclusions Therefore, our findings suggest that Cug2 is required for normal mitosis during early neurogenesis and has functions in neuronal cell maintenance, thus demonstrating that the cug2 deficient embryos may provide a model system for human neurodegenerative disorders.

  2. Types of Bipolar Disorder

    Science.gov (United States)

    ... many people have bipolar disorder along with another illness such as anxiety disorder, substance abuse, or an eating disorder. People with ... are sometimes misdiagnosed with schizophrenia. Anxiety and ADHD: ... such as bipolar disorder. Risk Factors Scientists are ...

  3. Cytokines in bipolar disorder

    DEFF Research Database (Denmark)

    Munkholm, Klaus; Vinberg, Maj; Vedel Kessing, Lars

    2012-01-01

    to affective state. METHODS: We conducted a systemtic review of studies measuring endogenous cytokine concentrations in patients with bipolar disorder and a meta-analysis, reporting results according to the PRISMA statement. RESULTS: Thirteen studies were included, comprising 556 bipolar disorder patients......BACKGROUND: Current research and hypothesis regarding the pathophysiology of bipolar disorder suggests the involvement of immune system dysfunction that is possibly related to disease activity. Our objective was to systematically review evidence of cytokine alterations in bipolar disorder according...

  4. Local sleep spindle modulations in relation to specific memory cues

    NARCIS (Netherlands)

    Cox, R.; Hofman, W.F.; de Boer, M.; Talamini, L.M.

    2014-01-01

    Sleep spindles have been connected to memory processes in various ways. In addition, spindles appear to be modulated at the local cortical network level. We investigated whether cueing specific memories during sleep leads to localized spindle modulations in humans. During learning of word-location

  5. Endoplasmic reticulum generates calcium signalling microdomains around the nucleus and spindle in syncytial Drosophila embryos.

    Science.gov (United States)

    Parry, H; McDougall, A; Whitaker, M

    2006-06-01

    Cell cycle calcium signals are generated by inositol trisphosphate-mediated release of calcium from internal stores [Ciapa, Pesando, Wilding and Whitaker (1994) Nature (London) 368, 875-878; Groigno and Whitaker (1998) Cell 92, 193-204]. The major internal calcium store is the ER (endoplasmic reticulum): the spatial organization of the ER during mitosis is important in defining a microdomain around the nucleus and mitotic spindle in early Drosophila embryos [Parry, McDougall and Whitaker (2005) J. Cell Biol. 171, 47-59]. Nuclear divisions in syncytial Drosophila embryos are accompanied by both cortical and nuclear localized calcium transients. Mitosis is prevented by the InsP(3) antagonists Xestospongin C and heparin. Nuclear-localized transients and cortical transients rely on extraembryonic calcium, suggesting that ER calcium levels are maintained by calcium influx.

  6. Mitosis-specific phosphorylation of PML at T409 regulates spindle checkpoint.

    Science.gov (United States)

    Jin, J; Liu, J

    2016-08-31

    During mitosis, Promyelocytic leukemia nuclear bodies (PML NBs) change dramatically in morphology and composition, but little is known about function of PML in mitosis. Here, we show that PML is phosphorylated at T409 (PML p409) in a mitosis-specific manner. More importantly, PML p409 contributes to maintain the duration of pro-metaphase and regulates spindle checkpoint. Deficient PML p409 caused a shortening of pro-metaphase and challenged the nocodazole-triggered mitotic arrest. T409A mutation led to a higher frequency of misaligned chromosomes on metaphase plate, and subsequently death in late mitosis. In addition, inhibition of PML p409 repressed growth of tumor cells, suggesting that PML p409 is a potential target for cancer therapy. Collectively, our study demonstrated an important phosphorylated site of PML, which contributed to explore the role of PML in mitosis.

  7. Dgp71WD is required for the assembly of the acentrosomal Meiosis I spindle, and is not a general targeting factor for the γ-TuRC

    Directory of Open Access Journals (Sweden)

    Richard F. Reschen

    2012-03-01

    Dgp71WD/Nedd1 proteins are essential for mitotic spindle formation. In human cells, Nedd1 targets γ-tubulin to both centrosomes and spindles, but in other organisms the function of Dgp71WD/Nedd1 is less clear. In Drosophila cells, Dgp71WD plays a major part in targeting γ-tubulin to spindles, but not centrosomes, while in Xenopus egg extracts, Nedd1 acts as a more general microtubule (MT organiser that can function independently of γ-tubulin. The interpretation of these studies, however, is complicated by the fact that some residual Dgp71WD/Nedd1 is likely present in the cells/extracts analysed. Here we generate a Dgp71WD null mutant lacking all but the last 12 nucleotides of coding sequence. The complete loss of Dgp71WD has no quantifiable effect on γ-tubulin or Centrosomin recruitment to the centrosome in larval brain cells. The recruitment of γ-tubulin to spindle MTs, however, is severely impaired, and spindle MT density is reduced in a manner that is indistinguishable from cells lacking Augmin or γ-TuRC function. In contrast, the absence of Dgp71WD leads to defects in the assembly of the acentrosomal female Meiosis I spindle that are more severe than those seen in Augmin or γ-TuRC mutants, indicating that Dgp71WD has additional functions that are independent of these complexes in oocytes. Moreover, the localisation of bicoid RNA during oogenesis, which requires γ-TuRC function, is unperturbed in Dgp71WD120 mutants. Thus, Dgp71WD is not simply a general cofactor required for γ-TuRC and/or Augmin targeting, and it appears to have a crucial role independent of these complexes in the acentrosomal Meiosis I spindle.

  8. Deep intermuscular spindle-cell lipoma

    African Journals Online (AJOL)

    Key Words: lipoma, spindle-cell, intermuscular. We report the case of ... cell lipoma. By pressure on the neurovascular bundle this tumour caused neurological symptoms in the affected leg. The clinical. 1 presentation, investigations, surgical intra- i operative Tidings, the .... by pressure on adjacent nerve trunks as happened.

  9. Laryngeal spindle cell liporna: case report

    African Journals Online (AJOL)

    University Hospital "Queen Ioanna", Sofia Bulgaria. Key words: Larynx , spindle cell, lipoma. This is a case report of a 24-year-old female patient who presented with a history of hoarseness of the voice, dysphagia and difficulty in breathing. A mass located on the laryngeal surface of the epiglottis was found and removed.

  10. Psychotic and Bipolar Disorders: Bipolar Disorder.

    Science.gov (United States)

    Holder, Sarah D

    2017-04-01

    Bipolar disorder is a severe chronic mental illness that affects a large number of individuals. This disorder is separated into two major types, bipolar I disorder, with mania and typically recurrent depression, and bipolar II disorder, with recurrent major depression and hypomania. Patients with bipolar disorder spend the majority of time experiencing depression, and this typically is the presenting symptom. Because outcomes are improved with earlier diagnosis and treatment, physicians should maintain a high index of suspicion for bipolar disorder. The most effective long-term treatments are lithium and valproic acid, although other drugs also are used. In addition to referral to a mental health subspecialist for initiation and management of drug treatment, patients with bipolar disorder should be provided with resources for psychotherapy. Several comorbidities commonly associated with bipolar disorder include other mental disorders, substance use disorders, migraine headaches, chronic pain, stroke, metabolic syndrome, and cardiovascular disease. Family physicians who care for patients with bipolar disorder should focus their efforts on prevention and management of comorbidities. These patients should be assessed continually for risk of suicide because they are at high risk and their suicide attempts tend to be successful. Written permission from the American Academy of Family Physicians is required for reproduction of this material in whole or in part in any form or medium.

  11. Interlinked bistable mechanisms generate robust mitotic transitions.

    Science.gov (United States)

    Hutter, Lukas H; Rata, Scott; Hochegger, Helfrid; Novák, Béla

    2017-10-18

    The transitions between phases of the cell cycle have evolved to be robust and switch-like, which ensures temporal separation of DNA replication, sister chromatid separation, and cell division. Mathematical models describing the biochemical interaction networks of cell cycle regulators attribute these properties to underlying bistable switches, which inherently generate robust, switch-like, and irreversible transitions between states. We have recently presented new mathematical models for two control systems that regulate crucial transitions in the cell cycle: mitotic entry and exit, 1 and the mitotic checkpoint. 2 Each of the two control systems is characterized by two interlinked bistable switches. In the case of mitotic checkpoint control, these switches are mutually activating, whereas in the case of the mitotic entry/exit network, the switches are mutually inhibiting. In this Perspective we describe the qualitative features of these regulatory motifs and show that having two interlinked bistable mechanisms further enhances robustness and irreversibility. We speculate that these network motifs also underlie other cell cycle transitions and cellular transitions between distinct biochemical states.

  12. Nutrition and Bipolar Depression.

    Science.gov (United States)

    Beyer, John L; Payne, Martha E

    2016-03-01

    As with physical conditions, bipolar disorder is likely to be impacted by diet and nutrition. Patients with bipolar disorder have been noted to have relatively unhealthy diets, which may in part be the reason they also have an elevated risk of metabolic syndrome and obesity. An improvement in the quality of the diet should improve a bipolar patient's overall health risk profile, but it may also improve their psychiatric outcomes. New insights into biological dysfunctions that may be present in bipolar disorder have presented new theoretic frameworks for understanding the relationship between diet and bipolar disorder. Copyright © 2016 Elsevier Inc. All rights reserved.

  13. Bipolar Treatment: Are Bipolar I and Bipolar II Treated Differently?

    Science.gov (United States)

    ... management strategies. In addition to medications and other types of treatment, successful management of your bipolar disorder includes living a healthy lifestyle, such as getting enough sleep, eating a healthy diet and being physically active. ...

  14. Silencing of Nuclear Mitotic Apparatus protein (NuMA) accelerates the apoptotic disintegration of the nucleus.

    Science.gov (United States)

    Kivinen, Katri; Taimen, Pekka; Kallajoki, Markku

    2010-08-01

    One main feature of apoptosis is the sequential degradation of the nuclear structure, including the fragmentation of chromatin and caspase-mediated cleavage of various nuclear proteins. Among these proteins is the Nuclear Mitotic Apparatus protein (NuMA) which plays a specific role in the organization of the mitotic spindle. The exact function of NuMA in the interphase nucleus is unknown, but a number of reports have suggested that it may play a role in chromatin organization and/or gene expression. Here we show that upon cleavage in apoptotic cells, the N-terminal cleavage fragment of NuMA is solubilized while the C-terminal fragment remains associated with the condensed chromatin. Using pancaspase inhibitor z-VAD-fmk and caspase-3 deficient MCF-7 cells, we further show that the solubilization is dependent on caspase-mediated cleavage of NuMA. Finally, the silencing of NuMA by RNAi accelerated nuclear breakdown in apoptotic MCF-7 cells. These results suggest that NuMA may provide structural support in the interphase nucleus by contributing to the organization of chromatin.

  15. The Spindle Assembly Checkpoint in Arabidopsis Is Rapidly Shut Off during Severe Stress.

    Science.gov (United States)

    Komaki, Shinichiro; Schnittger, Arp

    2017-10-23

    The spindle assembly checkpoint (SAC) in animals and yeast assures equal segregation of chromosomes during cell division. The prevalent occurrence of polyploidy in flowering plants together with the observation that many plants can be readily forced to double their genomes by application of microtubule drugs raises the question of whether plants have a proper SAC. Here, we provide a functional framework of the core SAC proteins in Arabidopsis. We reveal that Arabidopsis will delay mitosis in a SAC-dependent manner if the spindle is perturbed. However, we also show that the molecular architecture of the SAC is unique in plants. Moreover, the SAC is short-lived and cannot stay active for more than 2 hr, after which the cell cycle is reset. This resetting opens the possibility for genome duplications and raises the hypothesis that a rapid termination of a SAC-induced mitotic arrest provides an adaptive advantage for plants impacting plant genome evolution. Copyright © 2017 Elsevier Inc. All rights reserved.

  16. Mutations in alpha- and beta-tubulin affect spindle formation in Chinese hamster ovary cells.

    Science.gov (United States)

    Abraham, I; Marcus, M; Cabral, F; Gottesman, M M

    1983-10-01

    Two Chinese hamster ovary cell lines with mutated beta-tubulins (Grs-2 and Cmd-4) and one that has a mutation in alpha-tubulin (Tax-1) are temperature sensitive for growth at 40.5 degrees C. To determine the functional defect in these mutant cells at the nonpermissive temperature, they were characterized with respect to cell cycle parameters and microtubule organization and function after relatively short periods at 40.5 degrees C. At the nonpermissive temperature all the mutants had normal appearing cytoplasmic microtubules. Premature chromosome condensation analysis failed to show any discrete step in the interphase cell cycle in which these mutants are arrested. These cells, however, show several defects at the nonpermissive temperature that appear related to the function of microtubules during mitosis. Time-lapse studies showed that mitosis was lengthened in the three mutant lines at 40.5 degrees C as compared with the wild-type cells at this temperature, resulting in a higher proportion of cells in mitosis after temperature shift. There was also a large increase in multinucleated cells in mutant populations after incubation at the nonpermissive temperature. Immunofluorescent studies using a monoclonal anti--alpha-tubulin antibody showed that the mutant cells had a high proportion of abnormal spindles at the nonpermissive temperature. The two altered beta-tubulins and the altered alpha-tubulin all were found to cause a similar phenotype at the high temperature that results in mitotic delay, defective cytokinesis, multinucleation, and ultimately, cell death. We conclude that spindle formation is the limiting microtubule function in these mutant cell lines at the nonpermissive temperature and that these cell lines will be of value for the study of the precise role of tubulin in mammalian spindle formation.

  17. Adenomatoid spindle cell thymomas: a clinicopathological and immunohistochemical study of 20 cases.

    Science.gov (United States)

    Weissferdt, Annikka; Kalhor, Neda; Suster, Saul; Moran, Cesar A

    2010-10-01

    Twenty cases of adenomatoid spindle cell thymomas are presented. The patients are 13 males and 7 females between 7 and 82 years of age (mean: 55 y). Clinically, all patients presented with symptoms of chest pain and shortness of breath. Radiologically, an anterior mediastinal mass was discovered, and complete surgical resection was performed in all of the patients. Grossly, the tumors were described as well-defined solid tumor masses surrounded by membranous tissue, which at cut surface show a light tan homogenous surface. Areas of necrosis, hemorrhage, and/or cystic degeneration were not observed in any of the cases. Histologically, all tumors showed similar histological features and were characterized by the presence of a spindle cellular proliferation with an "adenomatoid-like" appearance, which at higher magnification showed the presence of cells with a signet-ring cell-like appearance. Rare mitotic figures were seen in some cases. Seven tumors showed transcapsular invasion, whereas 13 cases were encapsulate. Immunohistochemical studies showed positive staining for broad-spectrum keratin and keratin 7 with only scattered cells positive for calretinin and epithelial membrane antigen. Other markers including S-100 protein, desmin, smooth muscle actin, and α-feto protein were negative. Follow-up information ranging from 4 to 96 months (average: 32.3 mo) was obtained in 17 patients showing that all patients were alive. The cases herein described highlight the importance of recognizing this unusual pattern of spindle cell thymomas to avoid misdiagnosis with other tumors, namely, when dealing with small mediastinoscopic biopsies.

  18. Kalanchoe tubiflora extract inhibits cell proliferation by affecting the mitotic apparatus

    Directory of Open Access Journals (Sweden)

    Hsieh Yi-Jen

    2012-09-01

    Full Text Available Abstract Background Kalanchoe tubiflora (KT is a succulent plant native to Madagascar, and is commonly used as a medicinal agent in Southern Brazil. The underlying mechanisms of tumor suppression are largely unexplored. Methods Cell viability and wound-healing were analyzed by MTT assay and scratch assay respectively. Cell cycle profiles were analyzed by FACS. Mitotic defects were analyzed by indirect immunofluoresence images. Results An n-Butanol-soluble fraction of KT (KT-NB was able to inhibit cell proliferation. After a 48 h treatment with 6.75 μg/ml of KT, the cell viability was less than 50% of controls, and was further reduced to less than 10% at higher concentrations. KT-NB also induced an accumulation of cells in the G2/M phase of the cell cycle as well as an increased level of cells in the subG1 phase. Instead of disrupting the microtubule network of interphase cells, KT-NB reduced cell viability by inducing multipolar spindles and defects in chromosome alignment. KT-NB inhibits cell proliferation and reduces cell viability by two mechanisms that are exclusively involved with cell division: first by inducing multipolarity; second by disrupting chromosome alignment during metaphase. Conclusion KT-NB reduced cell viability by exclusively affecting formation of the proper structure of the mitotic apparatus. This is the main idea of the new generation of anti-mitotic agents. All together, KT-NB has sufficient potential to warrant further investigation as a potential new anticancer agent candidate.

  19. NuMA localization, stability, and function in spindle orientation involve 4.1 and Cdk1 interactions.

    Science.gov (United States)

    Seldin, Lindsey; Poulson, Nicholas D; Foote, Henry P; Lechler, Terry

    2013-12-01

    The epidermis is a multilayered epithelium that requires asymmetric divisions for stratification. A conserved cortical protein complex, including LGN, nuclear mitotic apparatus (NuMA), and dynein/dynactin, plays a key role in establishing proper spindle orientation during asymmetric divisions. The requirements for the cortical recruitment of these proteins, however, remain unclear. In this work, we show that NuMA is required to recruit dynactin to the cell cortex of keratinocytes. NuMA's cortical recruitment requires LGN; however, LGN interactions are not sufficient for this localization. Using fluorescence recovery after photobleaching, we find that the 4.1-binding domain of NuMA is important for stabilizing its interaction with the cell cortex. This is functionally important, as loss of 4.1/NuMA interaction results in spindle orientation defects, using two distinct assays. Furthermore, we observe an increase in cortical NuMA localization as cells enter anaphase. Inhibition of Cdk1 or mutation of a single residue in NuMA mimics this effect. NuMA's anaphase localization is independent of LGN and 4.1 interactions, revealing two distinct mechanisms responsible for NuMA cortical recruitment at different stages of mitosis. This work highlights the complexity of NuMA localization and reveals the importance of NuMA cortical stability for productive force generation during spindle orientation.

  20. Dynein Light Intermediate Chain 2 Facilitates the Metaphase to Anaphase Transition by Inactivating the Spindle Assembly Checkpoint.

    Directory of Open Access Journals (Sweden)

    Sagar P Mahale

    Full Text Available The multi-functional molecular motor cytoplasmic dynein performs diverse essential roles during mitosis. The mechanistic importance of the dynein Light Intermediate Chain homologs, LIC1 and LIC2 is unappreciated, especially in the context of mitosis. LIC1 and LIC2 are believed to exist in distinct cytoplasmic dynein complexes as obligate subunits. LIC1 had earlier been reported to be required for metaphase to anaphase progression by inactivating the kinetochore-microtubule attachment-sensing arm of the spindle assembly checkpoint (SAC. However, the functional importance of LIC2 during mitosis remains elusive. Here we report prominent novel roles for the LIC2 subunit of cytoplasmic dynein in regulating the spindle assembly checkpoint. LIC2 depletion in mammalian cells led to prolonged metaphase arrest in the presence of an active SAC and also to stretched kinetochores, thus implicating it in SAC inactivation. Quantitative fluorescence microscopy of SAC components revealed accumulation of both attachment- and tension-sensing checkpoint proteins at metaphase kinetochores upon LIC2 depletion. These observations support a stronger and more diverse role in checkpoint inactivation for LIC2 in comparison to its close homolog LIC1. Our study uncovers a novel functional hierarchy during mitotic checkpoint inactivation between the closely related but homologous LIC subunits of cytoplasmic dynein. These subtle functional distinctions between dynein subpopulations could be exploited to study specific aspects of the spindle assembly checkpoint, which is a key mediator of fidelity in eukaryotic cell division.

  1. Bipolar soft connected, bipolar soft disconnected and bipolar soft compact spaces

    Directory of Open Access Journals (Sweden)

    Muhammad Shabir

    2017-06-01

    Full Text Available Bipolar soft topological spaces are mathematical expressions to estimate interpretation of data frameworks. Bipolar soft theory considers the core features of data granules. Bipolarity is important to distinguish between positive information which is guaranteed to be possible and negative information which is forbidden or surely false. Connectedness and compactness are the most important fundamental topological properties. These properties highlight the main features of topological spaces and distinguish one topology from another. Taking this into account, we explore the bipolar soft connectedness, bipolar soft disconnectedness and bipolar soft compactness properties for bipolar soft topological spaces. Moreover, we introduce the notion of bipolar soft disjoint sets, bipolar soft separation, and bipolar soft hereditary property and study on bipolar soft connected and disconnected spaces. By giving the detailed picture of bipolar soft connected and disconnected spaces we investigate bipolar soft compact spaces and derive some results related to this concept.

  2. The moyamoya disease susceptibility variant RNF213 R4810K (rs112735431) induces genomic instability by mitotic abnormality

    Energy Technology Data Exchange (ETDEWEB)

    Hitomi, Toshiaki [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Habu, Toshiyuki [Radiation Biology Center, Kyoto University, Kyoto (Japan); Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H. [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Osafune, Kenji [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Taura, Daisuke; Sone, Masakatsu [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko [Center for iPS Cell Research and Application (CiRA), Kyoto University, Kyoto (Japan); Hashikata, Hirokuni; Takagi, Yasushi [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Morito, Daisuke [Faculty of Life Sciences, Kyoto Sangyo University, Kyoto (Japan); Miyamoto, Susumu [Department of Neurosurgery, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Nakao, Kazuwa [Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto (Japan); Koizumi, Akio, E-mail: koizumi.akio.5v@kyoto-u.ac.jp [Department of Health and Environmental Sciences, Graduate School of Medicine, Kyoto University, Kyoto (Japan)

    2013-10-04

    Highlights: •Overexpression of RNF213 R4810K inhibited cell proliferation. •Overexpression of RNF213 R4810K had the time of mitosis 4-fold and mitotic failure. •R4810K formed a complex with MAD2 more readily than wild-type. •iPSECs from the MMD patients had elevated mitotic failure compared from the control. •RNF213 R4810K induced mitotic abnormality and increased risk of aneuploidy. -- Abstract: Moyamoya disease (MMD) is a cerebrovascular disease characterized by occlusive lesions in the Circle of Willis. The RNF213 R4810K polymorphism increases susceptibility to MMD. In the present study, we characterized phenotypes caused by overexpression of RNF213 wild type and R4810K variant in the cell cycle to investigate the mechanism of proliferation inhibition. Overexpression of RNF213 R4810K in HeLa cells inhibited cell proliferation and extended the time of mitosis 4-fold. Ablation of spindle checkpoint by depletion of mitotic arrest deficiency 2 (MAD2) did not shorten the time of mitosis. Mitotic morphology in HeLa cells revealed that MAD2 colocalized with RNF213 R4810K. Immunoprecipitation revealed an RNF213/MAD2 complex: R4810K formed a complex with MAD2 more readily than RNF213 wild-type. Desynchronized localization of MAD2 was observed more frequently during mitosis in fibroblasts from patients (n = 3, 61.0 ± 8.2%) compared with wild-type subjects (n = 6, 13.1 ± 7.7%; p < 0.01). Aneuploidy was observed more frequently in fibroblasts (p < 0.01) and induced pluripotent stem cells (iPSCs) (p < 0.03) from patients than from wild-type subjects. Vascular endothelial cells differentiated from iPSCs (iPSECs) of patients and an unaffected carrier had a longer time from prometaphase to metaphase than those from controls (p < 0.05). iPSECs from the patients and unaffected carrier had significantly increased mitotic failure rates compared with controls (p < 0.05). Thus, RNF213 R4810K induced mitotic abnormalities and increased risk of genomic instability.

  3. The moyamoya disease susceptibility variant RNF213 R4810K (rs112735431) induces genomic instability by mitotic abnormality

    International Nuclear Information System (INIS)

    Hitomi, Toshiaki; Habu, Toshiyuki; Kobayashi, Hatasu; Okuda, Hiroko; Harada, Kouji H.; Osafune, Kenji; Taura, Daisuke; Sone, Masakatsu; Asaka, Isao; Ameku, Tomonaga; Watanabe, Akira; Kasahara, Tomoko; Sudo, Tomomi; Shiota, Fumihiko; Hashikata, Hirokuni; Takagi, Yasushi; Morito, Daisuke; Miyamoto, Susumu; Nakao, Kazuwa; Koizumi, Akio

    2013-01-01

    Highlights: •Overexpression of RNF213 R4810K inhibited cell proliferation. •Overexpression of RNF213 R4810K had the time of mitosis 4-fold and mitotic failure. •R4810K formed a complex with MAD2 more readily than wild-type. •iPSECs from the MMD patients had elevated mitotic failure compared from the control. •RNF213 R4810K induced mitotic abnormality and increased risk of aneuploidy. -- Abstract: Moyamoya disease (MMD) is a cerebrovascular disease characterized by occlusive lesions in the Circle of Willis. The RNF213 R4810K polymorphism increases susceptibility to MMD. In the present study, we characterized phenotypes caused by overexpression of RNF213 wild type and R4810K variant in the cell cycle to investigate the mechanism of proliferation inhibition. Overexpression of RNF213 R4810K in HeLa cells inhibited cell proliferation and extended the time of mitosis 4-fold. Ablation of spindle checkpoint by depletion of mitotic arrest deficiency 2 (MAD2) did not shorten the time of mitosis. Mitotic morphology in HeLa cells revealed that MAD2 colocalized with RNF213 R4810K. Immunoprecipitation revealed an RNF213/MAD2 complex: R4810K formed a complex with MAD2 more readily than RNF213 wild-type. Desynchronized localization of MAD2 was observed more frequently during mitosis in fibroblasts from patients (n = 3, 61.0 ± 8.2%) compared with wild-type subjects (n = 6, 13.1 ± 7.7%; p < 0.01). Aneuploidy was observed more frequently in fibroblasts (p < 0.01) and induced pluripotent stem cells (iPSCs) (p < 0.03) from patients than from wild-type subjects. Vascular endothelial cells differentiated from iPSCs (iPSECs) of patients and an unaffected carrier had a longer time from prometaphase to metaphase than those from controls (p < 0.05). iPSECs from the patients and unaffected carrier had significantly increased mitotic failure rates compared with controls (p < 0.05). Thus, RNF213 R4810K induced mitotic abnormalities and increased risk of genomic instability

  4. Sleep spindles and intelligence: evidence for a sexual dimorphism.

    Science.gov (United States)

    Ujma, Péter P; Konrad, Boris Nikolai; Genzel, Lisa; Bleifuss, Annabell; Simor, Péter; Pótári, Adrián; Körmendi, János; Gombos, Ferenc; Steiger, Axel; Bódizs, Róbert; Dresler, Martin

    2014-12-03

    Sleep spindles are thalamocortical oscillations in nonrapid eye movement sleep, which play an important role in sleep-related neuroplasticity and offline information processing. Sleep spindle features are stable within and vary between individuals, with, for example, females having a higher number of spindles and higher spindle density than males. Sleep spindles have been associated with learning potential and intelligence; however, the details of this relationship have not been fully clarified yet. In a sample of 160 adult human subjects with a broad IQ range, we investigated the relationship between sleep spindle parameters and intelligence. In females, we found a positive age-corrected association between intelligence and fast sleep spindle amplitude in central and frontal derivations and a positive association between intelligence and slow sleep spindle duration in all except one derivation. In males, a negative association between intelligence and fast spindle density in posterior regions was found. Effects were continuous over the entire IQ range. Our results demonstrate that, although there is an association between sleep spindle parameters and intellectual performance, these effects are more modest than previously reported and mainly present in females. This supports the view that intelligence does not rely on a single neural framework, and stronger neural connectivity manifesting in increased thalamocortical oscillations in sleep is one particular mechanism typical for females but not males. Copyright © 2014 the authors 0270-6474/14/3416358-11$15.00/0.

  5. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    International Nuclear Information System (INIS)

    BARNEY, PATRICK S.; LAUFFER, JAMES P.; PETTEYS, REBECCA; REDMOND, JAMES M.; SULLIVAN, WILLIAM N.

    1999-01-01

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools, The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller

  6. Simplified Dynamic Analysis of Grinders Spindle Node

    Science.gov (United States)

    Demec, Peter

    2014-12-01

    The contribution deals with the simplified dynamic analysis of surface grinding machine spindle node. Dynamic analysis is based on the use of the transfer matrix method, which is essentially a matrix form of method of initial parameters. The advantage of the described method, despite the seemingly complex mathematical apparatus, is primarily, that it does not require for solve the problem of costly commercial software using finite element method. All calculations can be made for example in MS Excel, which is advantageous especially in the initial stages of constructing of spindle node for the rapid assessment of the suitability its design. After detailing the entire structure of spindle node is then also necessary to perform the refined dynamic analysis in the environment of FEM, which it requires the necessary skills and experience and it is therefore economically difficult. This work was developed within grant project KEGA No. 023TUKE-4/2012 Creation of a comprehensive educational - teaching material for the article Production technique using a combination of traditional and modern information technology and e-learning.

  7. Adaptive Spindle Balancing Using Magnetically Levitated Bearings

    Energy Technology Data Exchange (ETDEWEB)

    BARNEY,PATRICK S.; LAUFFER,JAMES P.; PETTEYS,REBECCA; REDMOND,JAMES M.; SULLIVAN,WILLIAM N.

    1999-09-20

    A technological break through for supporting rotating shafts is the active magnetic bearing (AMB). Active magnetic bearings offer some important advantages over conventional ball, roller or journal bearings such as reduced frictional drag, no physical contact in the bearing, no need for lubricants, compatibility with high vacuum and ultra-clean environments, and ability to control shaft position within the bearing. The disadvantages of the AMB system are the increased cost and complexity, reduced bearing stiffness and the need for a controller. Still, there are certain applications, such as high speed machining, biomedical devices, and gyroscopes, where the additional cost of an AMB system can be justified. The inherent actuator capabilities of the AMB offer the potential for active balancing of spindles and micro-shaping capabilities for machine tools, The work presented in this paper concentrates on an AMB test program that utilizes the actuator capability to dynamically balance a spindle. In this study, an unbalanced AMB spindle system was enhanced with an LMS (Least Mean Squares) algorithm combined with an existing PID (proportional, integral, differential) control. This enhanced controller significantly improved the concentricity of an intentionally unbalanced shaft. The study included dynamic system analysis, test validation, control design and simulation, as well as experimental implementation using a digital LMS controller.

  8. v-Src-induced nuclear localization of YAP is involved in multipolar spindle formation in tetraploid cells.

    Science.gov (United States)

    Kakae, Keiko; Ikeuchi, Masayoshi; Kuga, Takahisa; Saito, Youhei; Yamaguchi, Naoto; Nakayama, Yuji

    2017-01-01

    The protein-tyrosine kinase, c-Src, is involved in a variety of signaling events, including cell division. We have reported that v-Src, which is a mutant variant of the cellular proto-oncogene, c-Src, causes delocalization of Aurora B kinase, resulting in a furrow regression in cytokinesis and the generation of multinucleated cells. However, the effect of v-Src on mitotic spindle formation is unknown. Here we show that v-Src-expressing HCT116 and NIH3T3 cells undergo abnormal cell division, in which cells separate into more than two cells. Upon v-Src expression, the proportion of multinucleated cells is increased in a time-dependent manner. Flow cytometry analysis revealed that v-Src increases the number of cells having a ≥4N DNA content. Microscopic analysis showed that v-Src induces the formation of multipolar spindles with excess centrosomes. These results suggest that v-Src induces multipolar spindle formation by generating multinucleated cells. Tetraploidy activates the tetraploidy checkpoint, leading to a cell cycle arrest of tetraploid cells at the G1 phase, in which the nuclear exclusion of the transcription co-activator YAP plays a critical role. In multinucleated cells that are induced by cytochalasin B and the Plk1 inhibitor, YAP is excluded from the nucleus. However, v-Src prevents this nuclear exclusion of YAP through a decrease in the phosphorylation of YAP at Ser127 in multinucleated cells. Furthermore, v-Src decreases the expression level of p53, which also plays a critical role in the cell cycle arrest of tetraploid cells. These results suggest that v-Src promotes abnormal spindle formation in at least two ways: generation of multinucleated cells and a weakening of the tetraploidy checkpoint. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Form and Function of Sleep Spindles across the Lifespan

    Directory of Open Access Journals (Sweden)

    Brittany C. Clawson

    2016-01-01

    Full Text Available Since the advent of EEG recordings, sleep spindles have been identified as hallmarks of non-REM sleep. Despite a broad general understanding of mechanisms of spindle generation gleaned from animal studies, the mechanisms underlying certain features of spindles in the human brain, such as “global” versus “local” spindles, are largely unknown. Neither the topography nor the morphology of sleep spindles remains constant throughout the lifespan. It is likely that changes in spindle phenomenology during development and aging are the result of dramatic changes in brain structure and function. Across various developmental windows, spindle activity is correlated with general cognitive aptitude, learning, and memory; however, these correlations vary in strength, and even direction, depending on age and metrics used. Understanding these differences across the lifespan should further clarify how these oscillations are generated and their function under a variety of circumstances. We discuss these issues, and their translational implications for human cognitive function. Because sleep spindles are similarly affected in disorders of neurodevelopment (such as schizophrenia and during aging (such as neurodegenerative conditions, both types of disorders may benefit from therapies based on a better understanding of spindle function.

  10. NUP98 fusion oncoproteins interact with the APC/C(Cdc20) as a pseudosubstrate and prevent mitotic checkpoint complex binding.

    Science.gov (United States)

    Salsi, Valentina; Fantini, Sebastian; Zappavigna, Vincenzo

    2016-09-01

    NUP98 is a recurrent partner gene in translocations causing acute myeloid leukemias and myelodisplastic syndrome. The expression of NUP98 fusion oncoproteins has been shown to induce mitotic spindle defects and chromosome missegregation, which correlate with the capability of NUP98 fusions to cause mitotic checkpoint attenuation. We show that NUP98 oncoproteins physically interact with the APC/C(Cdc20) in the absence of the NUP98 partner protein RAE1, and prevent the binding of the mitotic checkpoint complex to the APC/C(Cdc20). NUP98 oncoproteins require the GLEBS-like domain present in their NUP98 moiety to bind the APC/C(Cdc20). We found that NUP98 wild-type is a substrate of APC/C(Cdc20) prior to mitotic entry, and that its binding to APC/C(Cdc20) is controlled via phosphorylation of a PEST sequence located within its C-terminal portion. We identify S606, within the PEST sequence, as a key target site, whose phosphorylation modulates the capability of NUP98 to interact with APC/C(Cdc20). We finally provide evidence for an involvement of the peptidyl-prolyl isomerase PIN1 in modulating the possible conformational changes within NUP98 that lead to its dissociation from the APC/C(Cdc20) during mitosis. Our results provide novel insight into the mechanisms underlying the aberrant capability of NUP98 oncoproteins to interact with APC/C(Cdc20) and to interfere with its function.

  11. MYC Is a Major Determinant of Mitotic Cell Fate

    OpenAIRE

    Topham, Caroline; Tighe, Anthony; Ly, Peter; Bennett, Ailsa; Sloss, Olivia; Nelson, Louisa; Ridgway, Rachel?A.; Huels, David; Littler, Samantha; Schandl, Claudia; Sun, Ying; Bechi, Beatrice; Procter, David?J.; Sansom, Owen?J.; Cleveland, Don?W.

    2015-01-01

    Summary Taxol and other antimitotic agents are frontline chemotherapy agents but the mechanisms responsible for patient benefit remain unclear. Following a genome-wide siRNA screen, we identified the oncogenic transcription factor Myc as a taxol sensitizer. Using time-lapse imaging to correlate mitotic behavior with cell fate, we show that Myc sensitizes cells to mitotic blockers and agents that accelerate mitotic progression. Myc achieves this by upregulating a cluster of redundant pro-apopt...

  12. Bipolar Disorder - Multiple Languages

    Science.gov (United States)

    ... MP3 Bipolar Disorder (An Introduction) - English MP4 Bipolar Disorder (An Introduction) - español (Spanish) MP4 Healthy Roads Media Characters not displaying correctly on this page? See language display issues . Return to the MedlinePlus Health Information ...

  13. Magnetic bipolar transistor

    OpenAIRE

    Fabian, Jaroslav; Zutic, Igor; Sarma, S. Das

    2003-01-01

    A magnetic bipolar transistor is a bipolar junction transistor with one or more magnetic regions, and/or with an externally injected nonequilibrium (source) spin. It is shown that electrical spin injection through the transistor is possible in the forward active regime. It is predicted that the current amplification of the transistor can be tuned by spin.

  14. Coordination of cell cycle progression and mitotic spindle assembly involves histone H3 lysine 4 methylation by set1/COMPASS

    NARCIS (Netherlands)

    Beilharz, Traude H.; Harrison, Paul F.; Miles, Douglas Maya; See, Michael Ming; Le, Uyen Minh Merry; Kalanon, Ming; Curtis, Melissa Jane; Hasan, Qambar; Saksouk, Julie; Margaritis, Thanasis; Holstege, Frank; Geli, Vincent; Dichtl, Bernhard

    2017-01-01

    Methylation of histone H3 lysine 4 (H3K4) by Set1 complex/COMPASS is a hallmark of eukaryotic chromatin, but it remains poorly understood how this post-translational modification contributes to the regulation of biological processes like the cell cycle. Here, we report a H3K4 methylation-dependent

  15. Properties of Bipolar Fuzzy Hypergraphs

    OpenAIRE

    Akram, M.; Dudek, W. A.; Sarwar, S.

    2013-01-01

    In this article, we apply the concept of bipolar fuzzy sets to hypergraphs and investigate some properties of bipolar fuzzy hypergraphs. We introduce the notion of $A-$ tempered bipolar fuzzy hypergraphs and present some of their properties. We also present application examples of bipolar fuzzy hypergraphs.

  16. Sleep Spindles as Biomarker for Early Detection of Neurodegenerative Disorders

    DEFF Research Database (Denmark)

    2015-01-01

    The present invention relates to the use of sleep spindles as a novel biomarker for early diagnosis of synucleinopathies, in particular Parkinson's disease (PD). The method is based on automatic detection of sleep spindles. The method may be combined with measurements of one or more further...

  17. Bipolar Disorder in Children

    Science.gov (United States)

    2014-01-01

    Although bipolar disorder historically was thought to only occur rarely in children and adolescents, there has been a significant increase in children and adolescents who are receiving this diagnosis more recently (Carlson, 2005). Nonetheless, the applicability of the current bipolar disorder diagnostic criteria for children, particularly preschool children, remains unclear, even though much work has been focused on this area. As a result, more work needs to be done to further the understanding of bipolar symptoms in children. It is hoped that this paper can assist psychologists and other health service providers in gleaning a snapshot of the literature in this area so that they can gain an understanding of the diagnostic criteria and other behaviors that may be relevant and be informed about potential approaches for assessment and treatment with children who meet bipolar disorder criteria. First, the history of bipolar symptoms and current diagnostic criteria will be discussed. Next, assessment strategies that may prove helpful for identifying bipolar disorder will be discussed. Then, treatments that may have relevance to children and their families will be discussed. Finally, conclusions regarding work with children who may have a bipolar disorder diagnosis will be offered. PMID:24800202

  18. Bipolar Disorder in Children

    Directory of Open Access Journals (Sweden)

    Kimberly Renk

    2014-01-01

    Full Text Available Although bipolar disorder historically was thought to only occur rarely in children and adolescents, there has been a significant increase in children and adolescents who are receiving this diagnosis more recently (Carlson, 2005. Nonetheless, the applicability of the current bipolar disorder diagnostic criteria for children, particularly preschool children, remains unclear, even though much work has been focused on this area. As a result, more work needs to be done to further the understanding of bipolar symptoms in children. It is hoped that this paper can assist psychologists and other health service providers in gleaning a snapshot of the literature in this area so that they can gain an understanding of the diagnostic criteria and other behaviors that may be relevant and be informed about potential approaches for assessment and treatment with children who meet bipolar disorder criteria. First, the history of bipolar symptoms and current diagnostic criteria will be discussed. Next, assessment strategies that may prove helpful for identifying bipolar disorder will be discussed. Then, treatments that may have relevance to children and their families will be discussed. Finally, conclusions regarding work with children who may have a bipolar disorder diagnosis will be offered.

  19. Using Micromanipulation to Analyze Control of Vertebrate Meiotic Spindle Size

    Directory of Open Access Journals (Sweden)

    Jun Takagi

    2013-10-01

    Full Text Available The polymerization/depolymerization dynamics of microtubules (MTs have been reported to contribute to control of the size and shape of spindles, but quantitative analysis of how the size and shape correlate with the amount and density of MTs in the spindle remains incomplete. Here, we measured these parameters using 3D microscopy of meiotic spindles that self-organized in Xenopus egg extracts and presented a simple equation describing the relationship among these parameters. To examine the validity of the equation, we cut the spindle into two fragments along the pole-to-pole axis by micromanipulation techniques that rapidly decrease the amount of MTs. The spheroidal shape spontaneously recovered within 5 min, but the size of each fragment remained small. The equation we obtained quantitatively describes how the spindle size correlates with the amount of MTs while maintaining the shape and the MT density.

  20. Sleep spindles predict stress-related increases in sleep disturbances

    Directory of Open Access Journals (Sweden)

    Thien Thanh eDang-Vu

    2015-02-01

    Full Text Available Background and Aim: Predisposing factors place certain individuals at higher risk for insomnia, especially in the presence of precipitating conditions such as stressful life events. Sleep spindles have been shown to play an important role in the preservation of sleep continuity. Lower spindle density might thus constitute an objective predisposing factor for sleep reactivity to stress. The aim of this study was therefore to evaluate the relationship between baseline sleep spindle density and the prospective change in insomnia symptoms in response to a standardized academic stressor. Methods: 12 healthy students had a polysomnography (PSG recording during a period of lower stress at the beginning of the academic semester, along with an assessment of insomnia complaints using the Insomnia Severity Index (ISI. They completed a second ISI assessment at the end of the semester, a period coinciding with the week prior to final examinations and thus higher stress. Spindle density, amplitude, duration and frequency, as well as sigma power were computed from C4-O2 electroencephalography (EEG derivation during stages N2-N3 of non-rapid-eye-movement (NREM sleep, across the whole night and for each NREM sleep period. To test for the relationship between spindle density and changes in insomnia symptoms in response to academic stress, spindle measurements at baseline were correlated with changes in ISI across the academic semester.Results: Spindle density (as well as spindle amplitude and sigma power, particularly during the first NREM sleep period, negatively correlated with changes in ISI (p < 0.05. Conclusion: Lower spindle activity, especially at the beginning of the night, prospectively predicted larger increases in insomnia symptoms in response to stress. This result indicates that individual differences in sleep spindle activity contribute to the differential vulnerability to sleep disturbances in the face of precipitating factors.

  1. Pioneering barren land: mitotic bookmarking by transcription factors.

    Science.gov (United States)

    Rada-Iglesias, Alvaro

    2013-02-25

    Genome condensation during mitosis presents a chromatin landscape largely inaccessible to RNA polymerase II and most transcription factors. Caravaca et al. (2013) now report in Genes and Development that the pioneer transcription factor FOXA1 is retained at mitotic chromosomes, bookmarking the genome to enable gene expression reestablishment upon mitotic exit. Copyright © 2013 Elsevier Inc. All rights reserved.

  2. Analysis of mitotic nondisjunction with Aspergillus nidulans.

    Science.gov (United States)

    Morpurgo, G; Bellincampi, D; Gualandi, G; Baldinelli, L; Crescenzi, O S

    1979-08-01

    Two methods to detect the induction of nondisjunction with a diploid stable strain of A. nidulans are described. The first method gives only qualitative results, while the second method is quantitative and dose-effect curves can be done. Some physiological parameters affecting the induction of nondisjunction can also be studied, because either quiescent or germinating conidia can be treated with the drug under test. Some agents inducing nondisjunction were also tested for the induction of point mutation and somatic crossing-over with these comparative analysis. Two classes of agents inducing nondisjunction may be detected: the first causes all possible types of genetic damage either on quiescent or germinating conidia (a representative of this class is MMS) and acts presumably on the DNA level; the second acts only on germinating conidia and does not produce point mutation or crossing over. A representative of this class is Benomyl which interferes with spindle microtubules. A list of compounds tests is included.

  3. Reversion of apoptotic resistance of TP53-mutated Burkitt lymphoma B-cells to spindle poisons by exogenous activation of JNK and p38 MAP kinases.

    Science.gov (United States)

    Farhat, M; Poissonnier, A; Hamze, A; Ouk-Martin, C; Brion, J-D; Alami, M; Feuillard, J; Jayat-Vignoles, C

    2014-05-01

    Defects in apoptosis are frequently the cause of cancer emergence, as well as cellular resistance to chemotherapy. These phenotypes may be due to mutations of the tumor suppressor TP53 gene. In this study, we examined the effect of various mitotic spindle poisons, including the new isocombretastatin derivative isoNH2CA-4 (a tubulin-destabilizing molecule, considered to bind to the colchicine site by analogy with combretastatin A-4), on BL (Burkitt lymphoma) cells. We found that resistance to spindle poison-induced apoptosis could be reverted in tumor protein p53 (TP53)-mutated cells by EBV (Epstein Barr virus) infection. This reversion was due to restoration of the intrinsic apoptotic pathway, as assessed by relocation of the pro-apoptotic molecule Bax to mitochondria, loss of mitochondrial integrity and activation of the caspase cascade with PARP (poly ADP ribose polymerase) cleavage. EBV sensitized TP53-mutated BL cells to all spindle poisons tested, including vincristine and taxol, an effect that was systematically downmodulated by pretreatment of cells with inhibitors of p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinases. Exogenous activation of p38 and JNK pathways by dihydrosphingosine reverted resistance of TP53-mutated BL cells to spindle poisons. Dihydrosphingosine treatment of TP53-deficient Jurkat and K562 cell lines was also able to induce cell death. We conclude that activation of p38 and JNK pathways may revert resistance of TP53-mutated cells to spindle poisons. This opens new perspectives for developing alternative therapeutic strategies when the TP53 gene is inactivated.

  4. Blebbishields and mitotic cells exhibit robust macropinocytosis.

    Science.gov (United States)

    Jinesh, Goodwin G; Kamat, Ashish M

    2017-03-01

    Cancer stem cells can survive and undergo transformation after apoptosis by initiating robust endocytosis. Endocytosis in-turn drives formation of serpentine filopodia, which promote construction of blebbishields from apoptotic bodies. However, the status and role of macropinocytosis in blebbishields is not known. Here, we show by scanning electron microscopy and by macropinocytosis assays that blebbishields exhibit robust macropinocytosis. Inhibiting dynamin-mediated endocytosis does not affect macropinocytosis in blebbishields or in mitotic cells. In addition, inhibiting macropinocytosis did not inhibit construction of blebbishields from apoptotic bodies. Thus, although apoptotic cancer stem cells exhibit robust macropinocytosis, macropinocytosis is not essential to generate blebbishields, although it may play other roles in blebbishield biology. © 2016 BioFactors, 43(2):181-186, 2017. © 2016 International Union of Biochemistry and Molecular Biology.

  5. The spindle assembly checkpoint: More than just keeping track of the spindle.

    OpenAIRE

    Lawrence, KS; Engebrecht, J

    2015-01-01

    Genome stability is essential for cell proliferation and survival. Consequently, genome integrity is monitored by two major checkpoints, the DNA damage response (DDR) and the spindle assembly checkpoint (SAC). The DDR monitors DNA lesions in G1, S, and G2 stages of the cell cycle and the SAC ensures proper chromosome segregation in M phase. There have been extensive studies characterizing the roles of these checkpoints in response to the processes for which they are named; however, emerging e...

  6. Dynein/Dynactin-mediated transport of kinetochore components off kinetochores and onto spindle poles induced by nordihydroguaiaretic acid.

    Directory of Open Access Journals (Sweden)

    Jakub K Famulski

    2011-01-01

    Full Text Available The mitotic checkpoint functions to ensure accurate chromosome segregation by regulating the progression from metaphase to anaphase. Once the checkpoint has been satisfied, it is inactivated in order to allow the cell to proceed into anaphase and complete the cell cycle. The minus end-directed microtubule motor dynein/dynactin has been implicated in the silencing of the mitotic checkpoint by "stripping" checkpoint proteins off kinetochores. A recent study suggested that Nordihydroguaiaretic acid (NDGA stimulates dynein/dynactin-mediated transport of its cargo including ZW10 (Zeste White 10. We analyzed the effects of NDGA on dynein/dynactin dependent transport of the RZZ (Zeste White 10, Roughdeal, Zwilch complex as well as other kinetochore components from kinetochores to spindle poles. Through this approach we have catalogued several kinetochore and centromere components as dynein/dynactin cargo. These include hZW10, hZwilch, hROD, hSpindly, hMad1, hMad2, hCENP-E, hCdc27, cyclin-B and hMps1. Furthermore, we found that treatment with NDGA induced a robust accumulation and complete stabilization of hZW10 at spindle poles. This finding suggests that NDGA may not induce dynein/dynactin transport but rather interfere with cargo release. Lastly, we determined that NDGA induced accumulation of checkpoint proteins at the poles requires dynein/dynactin-mediated transport, hZW10 kinetochore localization and kinetochore-microtubule attachments but not tension or Aurora B kinase activity.

  7. Genetics of bipolar disorder

    OpenAIRE

    Kerner, Berit

    2014-01-01

    Berit Kerner Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA Abstract: Bipolar disorder is a common, complex genetic disorder, but the mode of transmission remains to be discovered. Many researchers assume that common genomic variants carry some risk for manifesting the disease. The research community has celebrated the first genome-wide significant associations between common single nucleotide polymorphisms (SNPs) and bipolar ...

  8. Mitotic control of human papillomavirus genome-containing cells is regulated by the function of the PDZ-binding motif of the E6 oncoprotein

    Science.gov (United States)

    Marsh, Elizabeth K.; Delury, Craig P.; Davies, Nicholas J.; Weston, Christopher J.; Miah, Mohammed A.L.; Banks, Lawrence; Parish, Joanna L.

    2017-01-01

    The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification. PMID:28061478

  9. Mitotic control of human papillomavirus genome-containing cells is regulated by the function of the PDZ-binding motif of the E6 oncoprotein.

    Science.gov (United States)

    Marsh, Elizabeth K; Delury, Craig P; Davies, Nicholas J; Weston, Christopher J; Miah, Mohammed A L; Banks, Lawrence; Parish, Joanna L; Higgs, Martin R; Roberts, Sally

    2017-03-21

    The function of a conserved PDS95/DLG1/ZO1 (PDZ) binding motif (E6 PBM) at the C-termini of E6 oncoproteins of high-risk human papillomavirus (HPV) types contributes to the development of HPV-associated malignancies. Here, using a primary human keratinocyte-based model of the high-risk HPV18 life cycle, we identify a novel link between the E6 PBM and mitotic stability. In cultures containing a mutant genome in which the E6 PBM was deleted there was an increase in the frequency of abnormal mitoses, including multinucleation, compared to cells harboring the wild type HPV18 genome. The loss of the E6 PBM was associated with a significant increase in the frequency of mitotic spindle defects associated with anaphase and telophase. Furthermore, cells carrying this mutant genome had increased chromosome segregation defects and they also exhibited greater levels of genomic instability, as shown by an elevated level of centromere-positive micronuclei. In wild type HPV18 genome-containing organotypic cultures, the majority of mitotic cells reside in the suprabasal layers, in keeping with the hyperplastic morphology of the structures. However, in mutant genome-containing structures a greater proportion of mitotic cells were retained in the basal layer, which were often of undefined polarity, thus correlating with their reduced thickness. We conclude that the ability of E6 to target cellular PDZ proteins plays a critical role in maintaining mitotic stability of HPV infected cells, ensuring stable episome persistence and vegetative amplification.

  10. [Antidepressants in bipolar disorder].

    Science.gov (United States)

    Courtet, P; Samalin, L; Olié, E

    2011-12-01

    Whereas mania defines the bipolar disorder, depression is the major challenge of treatment. In general, depressions are more frequent, longer, with a major prognostic impact in terms of disability and suicide. How should we treat a patient with bipolar depression? Antidepressants are the treatment of choice for depression, but not in the bipolar disorder. In this context, we have traditionally accepted that antidepressants are effective but they were inducing a significant risk of destabilization of the bipolar disorder, because of the transitions to mania and rapid cycling. Current data reconsider both the two aspects of this risk-benefit ratio. The effectiveness of antidepressants finally seems very limited, especially after the more recent studies with a robust methodology. Manic switches and rapid cycling may not be increased, particularly with new antidepressants and mood stabilizer combinations. The current literature reminds us that these course's modalities are inherent to the disease, with numerous risk factors, and among them, exposure to antidepressants. Who are the bipolar patients who only get the benefits of antidepressant treatment? Research will tell. They are in any case limited. How to navigate in our treatment strategies ? By choosing first drugs that demonstrated efficacy in bipolar depression. When the situation is more complex, "primum non nocere" should lead to support the prescription of the antidepressant in association with mood stabilizer. Copyright © 2011 L’Encéphale. Published by Elsevier Masson SAS.. All rights reserved.

  11. Sleep spindling and fluid intelligence across adolescent development: sex matters

    Directory of Open Access Journals (Sweden)

    Róbert eBódizs

    2014-11-01

    Full Text Available Evidence supports the intricate relationship between sleep electroencephalogram (EEG spindling and cognitive abilities in children and adults. Although sleep EEG changes during adolescence index fundamental brain reorganization, a detailed analysis of sleep spindling and the spindle-intelligence relationship was not yet provided for adolescents. Therefore, adolescent development of sleep spindle oscillations were studied in a home polysomnographic study focusing on the effects of chronological age and developmentally acquired overall mental efficiency (fluid IQ with sex as a potential modulating factor. Subjects were 24 healthy adolescents (12 males with an age range of 15–22 years (mean: 18 years and fluid IQ of 91-126 (mean: 104.12, Raven Progressive Matrices Test. Slow spindles (SSs and fast spindles (FSs were analyzed in 21 EEG derivations by using the individual adjustment method. A significant age-dependent increase in average FS density (r = .57; p = .005 was found. Moreover, fluid IQ correlated with FS density (r = .43; p = .04 and amplitude (r = .41; p = .049. The latter effects were entirely driven by particularly reliable FS-IQ correlations in females [r = .80 (p = .002 and r = .67 (p = .012, for density and amplitude, respectively]. Region-specific analyses revealed that these correlations peak in the fronto-central regions. The control of the age-dependence of FS measures and IQ scores did not considerably reduce the spindle-IQ correlations with respect to FS density. The only positive spindle-index of fluid IQ in males turned out to be the frequency of FSs (r = .60, p = .04. Increases in FS density during adolescence may index reshaped structural connectivity related to white matter maturation in the late developing human brain. The continued development over this age range of cognitive functions is indexed by specific measures of sleep spindling unravelling gender differences in adolescent brain maturation and perhaps cognitive

  12. Phosphoproteomic Profiling Reveals Epstein-Barr Virus Protein Kinase Integration of DNA Damage Response and Mitotic Signaling.

    Directory of Open Access Journals (Sweden)

    Renfeng Li

    2015-12-01

    Full Text Available Epstein-Barr virus (EBV is etiologically linked to infectious mononucleosis and several human cancers. EBV encodes a conserved protein kinase BGLF4 that plays a key role in the viral life cycle. To provide new insight into the host proteins regulated by BGLF4, we utilized stable isotope labeling by amino acids in cell culture (SILAC-based quantitative proteomics to compare site-specific phosphorylation in BGLF4-expressing Akata B cells. Our analysis revealed BGLF4-mediated hyperphosphorylation of 3,046 unique sites corresponding to 1,328 proteins. Frequency analysis of these phosphosites revealed a proline-rich motif signature downstream of BGLF4, indicating a broader substrate recognition for BGLF4 than its cellular ortholog cyclin-dependent kinase 1 (CDK1. Further, motif analysis of the hyperphosphorylated sites revealed enrichment in ATM, ATR and Aurora kinase substrates while functional analyses revealed significant enrichment of pathways related to the DNA damage response (DDR, mitosis and cell cycle. Phosphorylation of proteins associated with the mitotic spindle assembly checkpoint (SAC indicated checkpoint activation, an event that inactivates the anaphase promoting complex/cyclosome, APC/C. Furthermore, we demonstrated that BGLF4 binds to and directly phosphorylates the key cellular proteins PP1, MPS1 and CDC20 that lie upstream of SAC activation and APC/C inhibition. Consistent with APC/C inactivation, we found that BGLF4 stabilizes the expression of many known APC/C substrates. We also noted hyperphosphorylation of 22 proteins associated the nuclear pore complex, which may contribute to nuclear pore disassembly and SAC activation. A drug that inhibits mitotic checkpoint activation also suppressed the accumulation of extracellular EBV virus. Taken together, our data reveal that, in addition to the DDR, manipulation of mitotic kinase signaling and SAC activation are mechanisms associated with lytic EBV replication. All MS data have been

  13. Spatial Rule-Based Modeling: A Method and Its Application to the Human Mitotic Kinetochore

    Directory of Open Access Journals (Sweden)

    Jan Huwald

    2013-07-01

    Full Text Available A common problem in the analysis of biological systems is the combinatorial explosion that emerges from the complexity of multi-protein assemblies. Conventional formalisms, like differential equations, Boolean networks and Bayesian networks, are unsuitable for dealing with the combinatorial explosion, because they are designed for a restricted state space with fixed dimensionality. To overcome this problem, the rule-based modeling language, BioNetGen, and the spatial extension, SRSim, have been developed. Here, we describe how to apply rule-based modeling to integrate experimental data from different sources into a single spatial simulation model and how to analyze the output of that model. The starting point for this approach can be a combination of molecular interaction data, reaction network data, proximities, binding and diffusion kinetics and molecular geometries at different levels of detail. We describe the technique and then use it to construct a model of the human mitotic inner and outer kinetochore, including the spindle assembly checkpoint signaling pathway. This allows us to demonstrate the utility of the procedure, show how a novel perspective for understanding such complex systems becomes accessible and elaborate on challenges that arise in the formulation, simulation and analysis of spatial rule-based models.

  14. A Bipolar Spindle of Antiparallel ParM Filaments Drives Bacterial Plasmid Segregation

    DEFF Research Database (Denmark)

    Gayathri, P; Fujii, T; Møller-Jensen, Jakob

    2012-01-01

    To ensure their stable inheritance by daughter cells during cell division, bacterial low copy-number plasmids make simple DNA segregating machines that use an elongating protein filament between sister plasmids. In the ParMRC system of Escherichia coli R1 plasmid, ParM, an actin-like protein, forms...

  15. Activation of JNK triggers release of Brd4 from mitotic chromosomes and mediates protection from drug-induced mitotic stress.

    Directory of Open Access Journals (Sweden)

    Akira Nishiyama

    Full Text Available Some anti-cancer drugs, including those that alter microtubule dynamics target mitotic cells and induce apoptosis in some cell types. However, such drugs elicit protective responses in other cell types allowing cells to escape from drug-induced mitotic inhibition. Cells with a faulty protective mechanism undergo defective mitosis, leading to genome instability. Brd4 is a double bromodomain protein that remains on chromosomes during mitosis. However, Brd4 is released from mitotic chromosomes when cells are exposed to anti-mitotic drugs including nocodazole. Neither the mechanisms, nor the biological significance of drug-induced Brd4 release has been fully understood. We found that deletion of the internal C-terminal region abolished nocodazole induced Brd4 release from mouse P19 cells. Furthermore, cells expressing truncated Brd4, unable to dissociate from chromosomes were blocked from mitotic progression and failed to complete cell division. We also found that pharmacological and peptide inhibitors of the c-jun-N-terminal kinases (JNK pathway, but not inhibitors of other MAP kinases, prevented release of Brd4 from chromosomes. The JNK inhibitor that blocked Brd4 release also blocked mitotic progression. Further supporting the role of JNK in Brd4 release, JNK2-/- embryonic fibroblasts were defective in Brd4 release and sustained greater inhibition of cell growth after nocodazole treatment. In sum, activation of JNK pathway triggers release of Brd4 from chromosomes upon nocodazole treatment, which mediates a protective response designed to minimize drug-induced mitotic stress.

  16. Depression and Bipolar Support Alliance

    Science.gov (United States)

    Depression and Bipolar Support Alliance Crisis Hotline Information Coping with a Crisis Suicide Prevention Information Psychiatric Hospitalization ... sign-up Education info, training, events Mood Disorders Depression Bipolar Disorder Anxiety Screening Center Co-occurring Illnesses/ ...

  17. Bipolar Affective Disorder and Migraine

    Directory of Open Access Journals (Sweden)

    Birk Engmann

    2012-01-01

    Full Text Available This paper consists of a case history and an overview of the relationship, aetiology, and treatment of comorbid bipolar disorder migraine patients. A MEDLINE literature search was used. Terms for the search were bipolar disorder bipolar depression, mania, migraine, mood stabilizer. Bipolar disorder and migraine cooccur at a relatively high rate. Bipolar II patients seem to have a higher risk of comorbid migraine than bipolar I patients have. The literature on the common roots of migraine and bipolar disorder, including both genetic and neuropathological approaches, is broadly discussed. Moreover, bipolar disorder and migraine are often combined with a variety of other affective disorders, and, furthermore, behavioural factors also play a role in the origin and course of the diseases. Approach to treatment options is also difficult. Several papers point out possible remedies, for example, valproate, topiramate, which acts on both diseases, but no first-choice treatments have been agreed upon yet.

  18. Three-dimensional tracking of plus-tips by lattice light-sheet microscopy permits the quantification of microtubule growth trajectories within the mitotic apparatus

    Science.gov (United States)

    Yamashita, Norio; Morita, Masahiko; Legant, Wesley R.; Chen, Bi-Chang; Betzig, Eric; Yokota, Hideo; Mimori-Kiyosue, Yuko

    2015-10-01

    Mitotic apparatus, which comprises hundreds of microtubules, plays an essential role in cell division, ensuring the correct segregation of chromosomes into each daughter cell. To gain insight into its regulatory mechanisms, it is essential to detect and analyze the behavior of individual microtubule filaments. However, the discrimination of discrete microtubule filaments within the mitotic apparatus is beyond the capabilities of conventional light microscopic technologies. Recently, we detected three-dimensional (3-D) microtubule growth dynamics within the cellular cytoplasmic space using lattice light-sheet microscopy in conjunction with microtubule growth marker protein end-binding 1, a microtubule plus-end-tracking protein, which was fused to green fluorescent protein (EB1-GFP). This technique enables high-resolution 3-D imaging at subsecond intervals. We adapted mathematical computing and geometric representation techniques to analyze spatial variations in microtubule growth dynamics within the mitotic spindle apparatus. Our analytical approach enabled the different dynamic properties of individual microtubules to be determined, including the direction and speed of their growth, and their growth duration within a 3-D spatial map. Our analysis framework provides an important step toward a more comprehensive understanding of the mechanisms driving cellular machinery at the whole-cell level.

  19. A direct role of Mad1 in the spindle assembly checkpoint beyond Mad2 kinetochore recruitment

    DEFF Research Database (Denmark)

    Kruse, Thomas; Larsen, Marie Sofie Yoo; Sedgwick, Garry G

    2014-01-01

    The spindle assembly checkpoint (SAC) ensures accurate chromosome segregation by delaying entry into anaphase until all sister chromatids have become bi-oriented. A key component of the SAC is the Mad2 protein, which can adopt either an inactive open (O-Mad2) or active closed (C-Mad2) conformation....... The conversion of O-Mad2 into C-Mad2 at unattached kinetochores is thought to be a key step in activating the SAC. The "template model" proposes that this is achieved by the recruitment of soluble O-Mad2 to C-Mad2 bound at kinetochores through its interaction with Mad1. Whether Mad1 has additional roles...... in the SAC beyond recruitment of C-Mad2 to kinetochores has not yet been addressed. Here, we show that Mad1 is required for mitotic arrest even when C-Mad2 is artificially recruited to kinetochores, indicating that it has indeed an additional function in promoting the checkpoint. The C-terminal globular...

  20. The Wnt pathway controls cell death engulfment, spindle orientation, and migration through CED-10/Rac.

    Directory of Open Access Journals (Sweden)

    Juan Cabello

    2010-02-01

    Full Text Available Wnt signalling pathways have extremely diverse functions in animals, including induction of cell fates or tumours, guidance of cell movements during gastrulation, and the induction of cell polarity. Wnt can induce polar changes in cellular morphology by a remodelling of the cytoskeleton. However, how activation of the Frizzled receptor induces cytoskeleton rearrangement is not well understood. We show, by an in depth 4-D microscopy analysis, that the Caenorhabditis elegans Wnt pathway signals to CED-10/Rac via two separate branches to regulate modulation of the cytoskeleton in different cellular situations. Apoptotic cell clearance and migration of the distal tip cell require the MOM-5/Fz receptor, GSK-3 kinase, and APC/APR-1, which activate the CED-2/5/12 branch of the engulfment machinery. MOM-5 (Frizzled thus can function as an engulfment receptor in C. elegans. Our epistatic analyses also suggest that the two partially redundant signalling pathways defined earlier for engulfment may act in a single pathway in early embryos. By contrast, rearrangement of mitotic spindles requires the MOM-5/Fz receptor, GSK-3 kinase, and beta-catenins, but not the downstream factors LIT-1/NLK or POP-1/Tcf. Taken together, our results indicate that in multiple developmental processes, CED-10/Rac can link polar signals mediated by the Wnt pathway to rearrangements of the cytoskeleton.

  1. TBCD links centriologenesis, spindle microtubule dynamics, and midbody abscission in human cells.

    Directory of Open Access Journals (Sweden)

    Mónica López Fanarraga

    2010-01-01

    Full Text Available Microtubule-organizing centers recruit alpha- and beta-tubulin polypeptides for microtubule nucleation. Tubulin synthesis is complex, requiring five specific cofactors, designated tubulin cofactors (TBCs A-E, which contribute to various aspects of microtubule dynamics in vivo. Here, we show that tubulin cofactor D (TBCD is concentrated at the centrosome and midbody, where it participates in centriologenesis, spindle organization, and cell abscission. TBCD exhibits a cell-cycle-specific pattern, localizing on the daughter centriole at G1 and on procentrioles by S, and disappearing from older centrioles at telophase as the protein is recruited to the midbody. Our data show that TBCD overexpression results in microtubule release from the centrosome and G1 arrest, whereas its depletion produces mitotic aberrations and incomplete microtubule retraction at the midbody during cytokinesis. TBCD is recruited to the centriole replication site at the onset of the centrosome duplication cycle. A role in centriologenesis is further supported in differentiating ciliated cells, where TBCD is organized into "centriolar rosettes". These data suggest that TBCD participates in both canonical and de novo centriolar assembly pathways.

  2. Modelling muscle spindle dynamics for a proprioceptive prosthesis

    OpenAIRE

    Williams, I; Constandinou, TG

    2013-01-01

    25.04.13 KB. Ok to add accepted version to Spiral. IEEE Muscle spindles are found throughout our skeletal muscle tissue and continuously provide us with a sense of our limbs position and motion (proprioception). This paper advances a model for generating artificial muscle spindle signals for a prosthetic limb, with the aim of one day providing amputees with a sense of feeling in their artificial limb. By utilising the Opensim biomechanical modelling package the relationship between a joint...

  3. Mitotic Diversity in Homeostatic Human Interfollicular Epidermis

    Directory of Open Access Journals (Sweden)

    Katharina Nöske

    2016-01-01

    Full Text Available Despite decades of skin research, regulation of proliferation and homeostasis in human epidermis is still insufficiently understood. To address the role of mitoses in tissue regulation, we utilized human long-term skin equivalents and systematically assessed mitoses during early epidermal development and long-term epidermal regeneration. We now demonstrate four different orientations: (1 horizontal, i.e., parallel to the basement membrane (BM and suggestive of symmetric divisions; (2 oblique with an angle of 45°–70°; or (3 perpendicular, suggestive of asymmetric division. In addition, we demonstrate a fourth substantial fraction of suprabasal mitoses, many of which are committed to differentiation (Keratin K10-positive. As verified also for normal human skin, this spatial mitotic organization is part of the regulatory program of human epidermal tissue homeostasis. As a potential marker for asymmetric division, we investigated for Numb and found that it was evenly spread in almost all undifferentiated keratinocytes, but indeed asymmetrically distributed in some mitoses and particularly frequent under differentiation-repressing low-calcium conditions. Numb deletion (stable knockdown by CRISPR/Cas9, however, did not affect proliferation, neither in a three-day follow up study by life cell imaging nor during a 14-day culture period, suggesting that Numb is not essential for the general control of keratinocyte division.

  4. Mitotic Diversity in Homeostatic Human Interfollicular Epidermis.

    Science.gov (United States)

    Nöske, Katharina; Stark, Hans-Jürgen; Nevaril, Leonard; Berning, Manuel; Langbein, Lutz; Goyal, Ashish; Diederichs, Sven; Boukamp, Petra

    2016-01-28

    Despite decades of skin research, regulation of proliferation and homeostasis in human epidermis is still insufficiently understood. To address the role of mitoses in tissue regulation, we utilized human long-term skin equivalents and systematically assessed mitoses during early epidermal development and long-term epidermal regeneration. We now demonstrate four different orientations: (1) horizontal, i.e., parallel to the basement membrane (BM) and suggestive of symmetric divisions; (2) oblique with an angle of 45°-70°; or (3) perpendicular, suggestive of asymmetric division. In addition, we demonstrate a fourth substantial fraction of suprabasal mitoses, many of which are committed to differentiation (Keratin K10-positive). As verified also for normal human skin, this spatial mitotic organization is part of the regulatory program of human epidermal tissue homeostasis. As a potential marker for asymmetric division, we investigated for Numb and found that it was evenly spread in almost all undifferentiated keratinocytes, but indeed asymmetrically distributed in some mitoses and particularly frequent under differentiation-repressing low-calcium conditions. Numb deletion (stable knockdown by CRISPR/Cas9), however, did not affect proliferation, neither in a three-day follow up study by life cell imaging nor during a 14-day culture period, suggesting that Numb is not essential for the general control of keratinocyte division.

  5. Micromechanical study of mitotic chromosome structure

    Science.gov (United States)

    Marko, John

    2011-03-01

    Our group has developed micromanipulation techniques for study of the highly compacted mitotic form of chromosome found in eukaryote cells during cell division. Each metaphase chromosome contains two duplicate centimeter-long DNA molecules, folded up by proteins into cylindrical structures several microns in length. Native chromosomes display linear and reversible stretching behavior over a wide range of extensions (up to 5x native length for amphibian chromosomes), described by a Young modulus of about 300 Pa. Studies using DNA-cutting and protein-cutting enzymes have revealed that metaphase chromosomes behave as a network of chromatin fibers held together by protein-based isolated crosslinks. Our results are not consistent with the more classical model of loops of chromatin attached to a protein-based structural organizer or ``scaffold". In short, our experiments indicate that metaphase chromosomes can be considered to be ``gels" of chromatin; the stretching modulus of a whole chromosome is consistent with stretching of the chromatin fibers contained within it. Experiments using topoisomerases suggest that topological constraints may play an appreciable role in confining chromatin in the metaphase chromosome. Finally, recent experiments on human chromosomes will be reviewed, including results of experiments where chromosome-folding proteins are specifically depleted using siRNA methods. Supported by NSF-MCB-1022117, DMR-0715099, PHY-0852130, DMR-0520513, NCI 1U54CA143869-01 (NU-PS-OC), and the American Heart Association.

  6. SB225002 promotes mitotic catastrophe in chemo-sensitive and -resistant ovarian cancer cells independent of p53 status in vitro.

    Directory of Open Access Journals (Sweden)

    Meirong Du

    Full Text Available Recent evidence indicates that CXCR2 signaling is crucial for cancer progression, and its antagonist SB225002 induces apoptosis in Wilms' tumor cells. Here, we investigated the effect of SB225002 on cell cycle progression and apoptosis induction in vitro, using CDDP-sensitive and -resistant OVCA cell lines with different p53 status (wild type, mutant or null. Adenovirus infection of wild-type p53 or transfection of p53 siRNA was used to over-express or knock-down p53. Cell cycle and apoptosis were determined by flow cytometry or Hoechst staining and observation of nuclear morphology. Our data demonstrated that SB225002 induced apoptosis in both wild-type and p53-deficient ovarian cancer (OVCA cells through alternative mechanisms. SB225002 promoted mitotic catastrophe, as evidenced by the accumulation of mitotic cells with spindle abnormalities, chromosome mis-segregation, multi-polar cell division, multiple nuclei, aneuploidy/polyploidy and subsequent extensive apoptosis. SB225002-induced mitotic catastrophe appeared to be mediated by down-regulation of checkpoint kinase Chk1 and Cdk1-cyclin B activation. In cells expressing wild-type p53 (OV2008 and C13*, SB225002 increased total and phospho-Ser p53 levels, and p53 knock-down decreased SB225002-induced apoptosis, without affecting premature mitosis. These results suggest that SB225002 induces p53-dependent apoptosis, and provokes mitotic catastrophe in p53-independent manner in p53 wild-type cells. Reconstitution with wild-type P53 in P53-null SKOV3 cell attenuated SB225002-induced mitotic catastrophe, suggesting p53 prevented mitotic catastrophe induced by SB225002 in p53-deficient OVCA cells. Finally, the effect of SB225002 could not be prevented by pretreatment with CXCR2 ligand or its neutralizing antibody. The present studies demonstrate for the first time that SB225002 has dual actions in OVCA cells, inducing classic apoptosis through p53 activation and provoking mitotic catastrophe in

  7. Magic with moulds: Meiotic and mitotic crossing over in Neurospora ...

    Indian Academy of Sciences (India)

    2006-02-16

    Feb 16, 2006 ... Home; Journals; Journal of Biosciences; Volume 31; Issue 1. Commentary: Magic with moulds: Meiotic and mitotic crossing over in Neurospora inversions and duplications. Durgadas P Kasbekar. Volume 31 Issue 1 March 2006 pp 3-4 ...

  8. Commentary: Magic with moulds: Meiotic and mitotic crossing over ...

    Indian Academy of Sciences (India)

    2006-02-16

    Feb 16, 2006 ... Home; Journals; Journal of Biosciences; Volume 31; Issue 1. Commentary: Magic with moulds: Meiotic and mitotic crossing over in Neurospora inversions and duplications. Durgadas P Kasbekar. Volume 31 Issue 1 March 2006 pp 3-4 ...

  9. Depressive and bipolar disorders

    DEFF Research Database (Denmark)

    Kessing, Lars Vedel; Hansen, Hanne Vibe; Demyttenaere, Koen

    2005-01-01

    BACKGROUND: There is increasing evidence that attitudes and beliefs are important in predicting adherence to treatment and medication in depressive and bipolar disorders. However, these attitudes have received little study in patients whose disorders were sufficiently severe to require...... hospitalization. METHOD: The Antidepressant Compliance Questionnaire (ADCQ) was mailed to a large population of patients with depressive or bipolar disorder, representative of patients treated in hospital settings in Denmark. RESULTS: Of the 1005 recipients, 49.9% responded to the letter. A large proportion....... Moreover, their partners agreed on these negative views. Women had a more negative view of the doctor-patient relationship than men, and patients with a depressive disorder had a more negative view of antidepressants than patients with bipolar disorder. The number of psychiatric hospitalizations...

  10. Mitotic Bookmarking: Maintaining the Stem Cell Identity during Mitosis.

    Science.gov (United States)

    Huang, Xin; Wang, Jianlong

    2017-06-01

    In Cell Reports, Liu et al. (2017) investigate mechanisms for how pluripotent stem cells maintain their identity during cell division. They show that the histone mark H3K27ac and pluripotency transcription factors remain associated with mitotic chromatin in ESCs and during iPSC reprogramming, demonstrating the importance of mitotic bookmarking in pluripotency. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. The molecular architecture of the yeast spindle pole body core determined by Bayesian integrative modeling.

    Science.gov (United States)

    Viswanath, Shruthi; Bonomi, Massimiliano; Kim, Seung Joong; Klenchin, Vadim A; Taylor, Keenan C; Yabut, King C; Umbreit, Neil T; Van Epps, Heather A; Meehl, Janet; Jones, Michele H; Russel, Daniel; Velazquez-Muriel, Javier A; Winey, Mark; Rayment, Ivan; Davis, Trisha N; Sali, Andrej; Muller, Eric G

    2017-11-07

    Microtubule-organizing centers (MTOCs) form, anchor, and stabilize the polarized network of microtubules in a cell. The central MTOC is the centrosome that duplicates during the cell cycle and assembles a bipolar spindle during mitosis to capture and segregate sister chromatids. Yet, despite their importance in cell biology, the physical structure of MTOCs is poorly understood. Here we determine the molecular architecture of the core of the yeast spindle pole body (SPB) by Bayesian integrative structure modeling based on in vivo fluorescence resonance energy transfer (FRET), small-angle x-ray scattering (SAXS), x-ray crystallography, electron microscopy, and two-hybrid analysis. The model is validated by several methods that include a genetic analysis of the conserved PACT domain that recruits Spc110, a protein related to pericentrin, to the SPB. The model suggests that calmodulin can act as a protein cross-linker and Spc29 is an extended, flexible protein. The model led to the identification of a single, essential heptad in the coiled-coil of Spc110 and a minimal PACT domain. It also led to a proposed pathway for the integration of Spc110 into the SPB. © 2017 Viswanath, Bonomi, et al. This article is distributed by The American Society for Cell Biology under license from the author(s). Two months after publication it is available to the public under an Attribution–Noncommercial–Share Alike 3.0 Unported Creative Commons License (http://creativecommons.org/licenses/by-nc-sa/3.0).

  12. Targeting the Mitotic Catastrophe Signaling Pathway in Cancer

    Science.gov (United States)

    Mc Gee, Margaret M.

    2015-01-01

    Mitotic catastrophe, as defined in 2012 by the International Nomenclature Committee on Cell Death, is a bona fide intrinsic oncosuppressive mechanism that senses mitotic failure and responds by driving a cell to an irreversible antiproliferative fate of death or senescence. Thus, failed mitotic catastrophe can promote the unrestrained growth of defective cells, thereby representing a major gateway to tumour development. Furthermore, the activation of mitotic catastrophe offers significant therapeutic advantage which has been exploited in the action of conventional and targeted anticancer agents. Yet, despite its importance in tumour prevention and treatment, the molecular mechanism of mitotic catastrophe is not well understood. A better understanding of the signals that determine cell fate following failed or defective mitosis will reveal new opportunities to selectively target and enhance the programme for therapeutic benefit and reveal biomarkers to predict patient response. This review is focused on the molecular mechanism of mitotic catastrophe induction and signalling and highlights current strategies to exploit the process in cancer therapy. PMID:26491220

  13. Topography-specific spindle frequency changes in Obstructive Sleep Apnea

    Directory of Open Access Journals (Sweden)

    V Suzana

    2012-07-01

    Full Text Available Abstract Background Sleep spindles, as detected on scalp electroencephalography (EEG, are considered to be markers of thalamo-cortical network integrity. Since obstructive sleep apnea (OSA is a known cause of brain dysfunction, the aim of this study was to investigate sleep spindle frequency distribution in OSA. Seven non-OSA subjects and 21 patients with OSA (11 mild and 10 moderate were studied. A matching pursuit procedure was used for automatic detection of fast (≥13Hz and slow (Hz spindles obtained from 30min samples of NREM sleep stage 2 taken from initial, middle and final night thirds (sections I, II and III of frontal, central and parietal scalp regions. Results Compared to non-OSA subjects, Moderate OSA patients had higher central and parietal slow spindle percentage (SSP in all night sections studied, and higher frontal SSP in sections II and III. As the night progressed, there was a reduction in central and parietal SSP, while frontal SSP remained high. Frontal slow spindle percentage in night section III predicted OSA with good accuracy, with OSA likelihood increased by 12.1%for every SSP unit increase (OR 1.121, 95% CI 1.013 - 1.239, p=0.027. Conclusions These results are consistent with diffuse, predominantly frontal thalamo-cortical dysfunction during sleep in OSA, as more posterior brain regions appear to maintain some physiological spindle frequency modulation across the night. Displaying changes in an opposite direction to what is expected from the aging process itself, spindle frequency appears to be informative in OSA even with small sample sizes, and to represent a sensitive electrophysiological marker of brain dysfunction in OSA.

  14. Novel multiple criteria decision making methods based on bipolar neu trosophic sets and bipolar neutrosophic graphs

    OpenAIRE

    Muhammad Akram; Musavarah Sarwar

    2017-01-01

    In this research article, we present certain notions of bipolar neutrosophic graphs. We study the dominating and independent sets of bipolar neutrosophic graphs. We describe novel multiple criteria decision making methods based on bipolar neutrosophic sets and bipolar neutrosophic graphs.

  15. Discrete bipolar universal integrals

    Czech Academy of Sciences Publication Activity Database

    Greco, S.; Mesiar, Radko; Rindone, F.

    2014-01-01

    Roč. 252, č. 1 (2014), s. 55-65 ISSN 0165-0114 R&D Projects: GA ČR GAP402/11/0378 Institutional support: RVO:67985556 Keywords : bipolar integral * universal integral * Choquet integral Subject RIV: BA - General Mathematics Impact factor: 1.986, year: 2014 http://library.utia.cas.cz/separaty/2014/E/mesiar-0432224.pdf

  16. Microtubule cross-linking triggers the directional motility of kinesin-5

    NARCIS (Netherlands)

    L.C. Kapitein (Lukas); B.H. Kwok (Benjamin); J.S. Weinger (Joshua); C.F. Schmidt (Christoph); T.M. Kapoor (Tarun); E.J.G. Peterman (Erwin)

    2008-01-01

    textabstractAlthough assembly of the mitotic spindle is known to be a precisely controlled process, regulation of the key motor proteins involved remains poorly understood. In eukaryotes, homotetrameric kinesin-5 motors are required for bipolar spindle formation. Eg5, the vertebrate kinesin-5, has

  17. [Spouses and bipolar disorder].

    Science.gov (United States)

    Ellouze, F; Ayedi, S; Cherif, W; Ben Abla, T; M'rad, M F

    2011-02-01

    To assess the quality of life of a population of spouses of bipolar patients compared with a control population. We conducted a cross-sectional study which included two groups: a group of 30 spouses of patients followed for bipolar I disorder according to DSM IV criteria and a second group of 30 subjects from the general population. Both groups were matched by age, sex, marital status and socioeconomic level. This device was designed to limit the differences between the two groups solely those of the bipolar illness. Evaluating the quality of life was achieved using the quality of life scale: SF-36. This is a scale that has already been translated and validated in dialect Arabic. Regarding sociodemographic variables, the two study groups differed only for: recreation, friendly relations and the couple relationship that included more and better skills among the control group. In the categorical approach, the quality of life was impaired in 60% of spouses and 40% of controls with a statistically significant difference. The following standardized dimensions: mental health (D4), limitation due to mental health (D5), life and relationship with others (D6) and perceived health (D8) and mental component (CM) were significantly altered in patients' spouses compared to controls. We found significant differences between the two groups for: overall average score (51.1 vs. 68.2), mental health (D4), limitation due to mental health (D5), life and relationship with others (D6), perceived health (D8) and perceived health (D8) standards. The impairment of quality of life of bipolar patients' spouses is related to the extra responsibility, stress, financial problems and health problems, stigma, and loss of security of the person loved. Considering the consequences that the appearance of bipolar disorder on the patient's spouse may have, certain measures must be proposed to improve their quality of life. Copyright © 2010 L'Encéphale, Paris. Published by Elsevier Masson SAS. All

  18. ON BIPOLAR SINGLE VALUED NEUTROSOPHIC GRAPHS

    OpenAIRE

    Broumi, Said; Talea, Mohamed; Bakali, Assia; Smarandache, Florentin

    2016-01-01

    In this article, we combine the concept of bipolar neutrosophic set and graph theory. We introduce the notions of bipolar single valued neutrosophic graphs, strong bipolar single valued neutrosophic graphs, complete bipolar single valued neutrosophic graphs, regular bipolar single valued neutrosophic graphs and investigate some of their related properties.

  19. Spindle Activity Orchestrates Plasticity during Development and Sleep

    Directory of Open Access Journals (Sweden)

    Christoph Lindemann

    2016-01-01

    Full Text Available Spindle oscillations have been described during early brain development and in the adult brain. Besides similarities in temporal patterns and involved brain areas, neonatal spindle bursts (NSBs and adult sleep spindles (ASSs show differences in their occurrence, spatial distribution, and underlying mechanisms. While NSBs have been proposed to coordinate the refinement of the maturating neuronal network, ASSs are associated with the implementation of acquired information within existing networks. Along with these functional differences, separate synaptic plasticity mechanisms seem to be recruited. Here, we review the generation of spindle oscillations in the developing and adult brain and discuss possible implications of their differences for synaptic plasticity. The first part of the review is dedicated to the generation and function of ASSs with a particular focus on their role in healthy and impaired neuronal networks. The second part overviews the present knowledge of spindle activity during development and the ability of NSBs to organize immature circuits. Studies linking abnormal maturation of brain wiring with neurological and neuropsychiatric disorders highlight the importance to better elucidate neonatal plasticity rules in future research.

  20. Spindle neurons of the human anterior cingulate cortex

    Science.gov (United States)

    Nimchinsky, E. A.; Vogt, B. A.; Morrison, J. H.; Hof, P. R.; Bloom, F. E. (Principal Investigator)

    1995-01-01

    The human anterior cingulate cortex is distinguished by the presence of an unusual cell type, a large spindle neuron in layer Vb. This cell has been noted numerous times in the historical literature but has not been studied with modern neuroanatomic techniques. For instance, details regarding the neuronal class to which these cells belong and regarding their precise distribution along both ventrodorsal and anteroposterior axes of the cingulate gyrus are still lacking. In the present study, morphological features and the anatomic distribution of this cell type were studied using computer-assisted mapping and immunocytochemical techniques. Spindle neurons are restricted to the subfields of the anterior cingulate cortex (Brodmann's area 24), exhibiting a greater density in anterior portions of this area than in posterior portions, and tapering off in the transition zone between anterior and posterior cingulate cortex. Furthermore, a majority of the spindle cells at any level is located in subarea 24b on the gyral surface. Immunocytochemical analysis revealed that the neurofilament protein triple was present in a large percentage of these neurons and that they did not contain calcium-binding proteins. Injections of the carbocyanine dye DiI into the cingulum bundle revealed that these cells are projection neurons. Finally, spindle cells were consistently affected in Alzheimer's disease cases, with an overall loss of about 60%. Taken together, these observations indicate that the spindle cells of the human cingulate cortex represent a morphological subpopulation of pyramidal neurons whose restricted distribution may be associated with functionally distinct areas.

  1. Early Intervention in Bipolar Disorder.

    Science.gov (United States)

    Vieta, Eduard; Salagre, Estela; Grande, Iria; Carvalho, André F; Fernandes, Brisa S; Berk, Michael; Birmaher, Boris; Tohen, Mauricio; Suppes, Trisha

    2018-01-24

    Bipolar disorder is a recurrent disorder that affects more than 1% of the world population and usually has its onset during youth. Its chronic course is associated with high rates of morbidity and mortality, making bipolar disorder one of the main causes of disability among young and working-age people. The implementation of early intervention strategies may help to change the outcome of the illness and avert potentially irreversible harm to patients with bipolar disorder, as early phases may be more responsive to treatment and may need less aggressive therapies. Early intervention in bipolar disorder is gaining momentum. Current evidence emerging from longitudinal studies indicates that parental early-onset bipolar disorder is the most consistent risk factor for bipolar disorder. Longitudinal studies also indicate that a full-blown manic episode is often preceded by a variety of prodromal symptoms, particularly subsyndromal manic symptoms, therefore supporting the existence of an at-risk state in bipolar disorder that could be targeted through early intervention. There are also identifiable risk factors that influence the course of bipolar disorder, some of them potentially modifiable. Valid biomarkers or diagnosis tools to help clinicians identify individuals at high risk of conversion to bipolar disorder are still lacking, although there are some promising early results. Pending more solid evidence on the best treatment strategy in early phases of bipolar disorder, physicians should carefully weigh the risks and benefits of each intervention. Further studies will provide the evidence needed to finish shaping the concept of early intervention.

  2. Robust mitotic entry is ensured by a latching switch

    Directory of Open Access Journals (Sweden)

    Chloe Tuck

    2013-07-01

    Cell cycle events are driven by Cyclin dependent kinases (CDKs and by their counter-acting phosphatases. Activation of the Cdk1:Cyclin B complex during mitotic entry is controlled by the Wee1/Myt1 inhibitory kinases and by Cdc25 activatory phosphatase, which are themselves regulated by Cdk1:Cyclin B within two positive circuits. Impairing these two feedbacks with chemical inhibitors induces a transient entry into M phase referred to as mitotic collapse. The pathology of mitotic collapse reveals that the positive circuits play a significant role in maintaining the M phase state. To better understand the function of these feedback loops during G2/M transition, we propose a simple model for mitotic entry in mammalian cells including spatial control over Greatwall kinase phosphorylation. After parameter calibration, the model is able to recapture the complex and non-intuitive molecular dynamics reported by Potapova et al. (Potapova et al., 2011. Moreover, it predicts the temporal patterns of other mitotic regulators which have not yet been experimentally tested and suggests a general design principle of cell cycle control: latching switches buffer the cellular stresses which accompany cell cycle processes to ensure that the transitions are smooth and robust.

  3. A dynamic mode of mitotic bookmarking by transcription factors.

    Science.gov (United States)

    Teves, Sheila S; An, Luye; Hansen, Anders S; Xie, Liangqi; Darzacq, Xavier; Tjian, Robert

    2016-11-19

    During mitosis, transcription is shut off, chromatin condenses, and most transcription factors (TFs) are reported to be excluded from chromosomes. How do daughter cells re-establish the original transcription program? Recent discoveries that a select set of TFs remain bound on mitotic chromosomes suggest a potential mechanism for maintaining transcriptional programs through the cell cycle termed mitotic bookmarking. Here we report instead that many TFs remain associated with chromosomes in mouse embryonic stem cells, and that the exclusion previously described is largely a fixation artifact. In particular, most TFs we tested are significantly enriched on mitotic chromosomes. Studies with Sox2 reveal that this mitotic interaction is more dynamic than in interphase and is facilitated by both DNA binding and nuclear import. Furthermore, this dynamic mode results from lack of transcriptional activation rather than decreased accessibility of underlying DNA sequences in mitosis. The nature of the cross-linking artifact prompts careful re-examination of the role of TFs in mitotic bookmarking.

  4. Life expectancy in bipolar disorder

    DEFF Research Database (Denmark)

    Kessing, Lars Vedel; Vradi, Eleni; Andersen, Per Kragh

    2015-01-01

    OBJECTIVE: Life expectancy in patients with bipolar disorder has been reported to be decreased by 11 to 20 years. These calculations are based on data for individuals at the age of 15 years. However, this may be misleading for patients with bipolar disorder in general as most patients have a later...... onset of illness. The aim of the present study was to calculate the remaining life expectancy for patients of different ages with a diagnosis of bipolar disorder. METHODS: Using nationwide registers of all inpatient and outpatient contacts to all psychiatric hospitals in Denmark from 1970 to 2012 we...... remaining life expectancy in bipolar disorder and that of the general population decreased with age, indicating that patients with bipolar disorder start losing life-years during early and mid-adulthood. CONCLUSIONS: Life expectancy in bipolar disorder is decreased substantially, but less so than previously...

  5. Bipolar Disorder and Alcoholism: Are They Related?

    Science.gov (United States)

    ... Is there a connection between bipolar disorder and alcoholism? Answers from Daniel K. Hall-Flavin, M.D. Bipolar disorder and alcoholism often occur together. Although the association between bipolar ...

  6. Force encoding in muscle spindles during stretch of passive muscle.

    Science.gov (United States)

    Blum, Kyle P; Lamotte D'Incamps, Boris; Zytnicki, Daniel; Ting, Lena H

    2017-09-01

    Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs) of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt) predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening) of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle lengthening conditions

  7. Force encoding in muscle spindles during stretch of passive muscle.

    Directory of Open Access Journals (Sweden)

    Kyle P Blum

    2017-09-01

    Full Text Available Muscle spindle proprioceptive receptors play a primary role in encoding the effects of external mechanical perturbations to the body. During externally-imposed stretches of passive, i.e. electrically-quiescent, muscles, the instantaneous firing rates (IFRs of muscle spindles are associated with characteristics of stretch such as length and velocity. However, even in passive muscle, there are history-dependent transients of muscle spindle firing that are not uniquely related to muscle length and velocity, nor reproduced by current muscle spindle models. These include acceleration-dependent initial bursts, increased dynamic response to stretch velocity if a muscle has been isometric, and rate relaxation, i.e., a decrease in tonic IFR when a muscle is held at a constant length after being stretched. We collected muscle spindle spike trains across a variety of muscle stretch kinematic conditions, including systematic changes in peak length, velocity, and acceleration. We demonstrate that muscle spindle primary afferents in passive muscle fire in direct relationship to muscle force-related variables, rather than length-related variables. Linear combinations of whole muscle-tendon force and the first time derivative of force (dF/dt predict the entire time course of transient IFRs in muscle spindle Ia afferents during stretch (i.e., lengthening of passive muscle, including the initial burst, the dynamic response to lengthening, and rate relaxation following lengthening. Similar to acceleration scaling found previously in postural responses to perturbations, initial burst amplitude scaled equally well to initial stretch acceleration or dF/dt, though later transients were only described by dF/dt. The transient increase in dF/dt at the onset of lengthening reflects muscle short-range stiffness due to cross-bridge dynamics. Our work demonstrates a critical role of muscle cross-bridge dynamics in history-dependent muscle spindle IFRs in passive muscle

  8. Sleep spindle activity in double cortex syndrome: a case report.

    Science.gov (United States)

    Sforza, Emilia; Marcoz, Jean-Pierre; Foletti, Giovanni

    2010-09-01

    Cortical dysgenesis is increasingly recognised as a cause of epilepsy. We report a case with double cortex heterotopia and secondarily generalized seizures with a generalised spike wave pattern. During the course of the disease, the child developed electrical status epilepticus in slow wave sleep. From the first examination, sleep pattern revealed increased frequency and amplitude of spindle activity, more evident in anterior areas. The role of the thalamocortical pathway in increased sleep spindle activity is discussed with emphasis on the possible role of altered thalamocortical pathways in abnormal cortical migration. A strong suspicion of cortical dysgenesis may therefore be based on specific EEG sleep patterns.

  9. [Creativity and bipolar disorder].

    Science.gov (United States)

    Maçkalı, Zeynep; Gülöksüz, Sinan; Oral, Timuçin

    2014-01-01

    The relationship between creativity and bipolar disorder has been an intriguing topic since ancient times. Early studies focused on describing characteristics of creative people. From the last quarter of the twentieth century, researchers began to focus on the relationship between mood disorders and creativity. Initially, the studies were based on biographical texts and the obtained results indicated a relationship between these two concepts. The limitations of the retrospective studies led the researchers to develop systematic investigations into this area. The systematic studies that have focused on artistic creativity have examined both the prevalence of mood disorders and the creative process. In addition, a group of researchers addressed the relationship in terms of affective temperaments. Through the end of the 90's, the scope of creativity was widened and the notion of everyday creativity was proposed. The emergence of this notion led researchers to investigate the associations of the creative process in ordinary (non-artist) individuals. In this review, the descriptions of creativity and creative process are mentioned. Also, the creative process is addressed with regards to bipolar disorder. Then, the relationship between creativity and bipolar disorder are evaluated in terms of aforementioned studies (biographical, systematic, psychobiographical, affective temperaments). In addition, a new model, the "Shared Vulnerability Model" which was developed to explain the relationship between creativity and psychopathology is introduced. Finally, the methodological limitations and the suggestions for resolving these limitations are included.

  10. Bipolar Disorder and Diabetes Mellitus

    Directory of Open Access Journals (Sweden)

    Sermin Kesebir

    2010-04-01

    Full Text Available Comorbid endocrine and cardiovascular situations with bipolar disorder usually result from the bipolar disorder itself or as a consequence of its treatment. With habits and lifestyle, genetic tendency and side effects, this situation is becoming more striking. Subpopulations of bipolar disorders patients should be considered at high risk for diabetes mellitus. The prevalence of diabetes mellitus in bipolar disorder may be three times greater than in the general population. Comorbidity of diabetes causes a pathophysiological overlapping in the neurobiological webs of bipolar cases. Signal mechanisms of glycocorticoid/insulin and immunoinflammatory effector systems are junction points that point out the pathophysiology between bipolar disorder and general medical cases susceptible to stress. Glycogen synthetase kinase (GSK-3 is a serine/treonine kinase and inhibits the transport of glucose stimulated by insulin. It is affected in diabetes, cancer, inflammation, Alzheimer disease and bipolar disorder. Hypoglycemic effect of lithium occurs via inhibiting glycogen synthetase kinase. When comorbid with diabetes, the other disease -for example bipolar disorder, especially during its acute manic episodes-, causes a serious situation that presents its influences for a lifetime. Choosing pharmacological treatment and treatment adherence are another important interrelated areas. The aim of this article is to discuss and review the etiological, clinical and therapeutic properties of diabetes mellitus and bipolar disorder comorbidity.

  11. Mitotic bookmarking of genes: a novel dimension to epigenetic control.

    Science.gov (United States)

    Zaidi, Sayyed K; Young, Daniel W; Montecino, Martin A; Lian, Jane B; van Wijnen, Andre J; Stein, Janet L; Stein, Gary S

    2010-08-01

    Regulatory machinery is focally organized in the interphase nucleus. The information contained in these focal nuclear microenvironments must be inherited during cell division to sustain physiologically responsive gene expression in progeny cells. Recent results suggest that focal mitotic retention of phenotypic transcription factors at promoters together with histone modifications and DNA methylation--a mechanism collectively known as gene bookmarking--is a novel parameter of inherited epigenetic control that sustains cellular identity after mitosis. The epigenetic signatures imposed by bookmarking poise genes for activation or suppression following mitosis. We discuss the implications of phenotypic transcription factor retention on mitotic chromosomes in biological control and disease.

  12. SGO1 maintains bovine meiotic and mitotic centromeric cohesions of sister chromatids and directly affects embryo development.

    Directory of Open Access Journals (Sweden)

    Feng-Xia Yin

    Full Text Available Shugoshin (SGO is a critical factor that enforces cohesion from segregation of paired sister chromatids during mitosis and meiosis. It has been studied mainly in invertebrates. Knowledge of SGO(s in a mammalian system has only been reported in the mouse and Hela cells. In this study, the functions of SGO1 in bovine oocytes during meiotic maturation, early embryonic development and somatic cell mitosis were investigated. The results showed that SGO1 was expressed from germinal vesicle (GV to the metaphase II stage. SGO1 accumulated on condensed and scattered chromosomes from pre-metaphase I to metaphase II. The over-expression of SGO1 did not interfere with the process of homologous chromosome separation, although once separated they were unable to move to the opposing spindle poles. This often resulted in the formation of oocytes with 60 replicated chromosomes. Depletion of SGO1 in GV oocytes affected chromosomal separation resulting in abnormal chromosome alignment at a significantly higher proportion than in control oocytes. Knockdown of SGO1 expression significantly decreased the embryonic developmental rate and quality. To further confirm the function(s of SGO1 during mitosis, bovine embryonic fibroblast cells were transfected with SGO1 siRNAs. SGO1 depletion induced the premature dissociation of chromosomal cohesion at the centromere and along the chromosome arm giving rise to abnormal appearing mitotic patterns. The results of this study infer that SGO1 is involved in the centromeric cohesion of sister chromatids and chromosomal movement towards the spindle poles. Depletion of SGO1 causes arrestment of cell division in meiosis and mitosis.

  13. The Nuclear Mitotic Apparatus (NuMA) protein is contributed by the donor cell nucleus in cloned porcine embryos.

    Science.gov (United States)

    Liu, Zhonghua; Schatten, Heide; Hao, Yanhong; Lai, Liangxue; Wax, David; Samuel, Melissa; Zhong, Zhi-Sheng; Sun, Qing-Yuan; Prather, Randall S

    2006-05-01

    The Nuclear Mitotic Apparatus (NuMA) protein is a multifunctional protein that is localized to the nucleus in interphase and to the poles of the mitotic apparatus during mitosis. In unfertilized porcine oocytes, NuMA is localized to the meiotic spindle. NuMA is removed along with the meiotic spindle during the enucleation process before reconstructing the egg by introducing the donor cell nucleus to produce cloned embryos. Questions have been raised regarding the source for NuMA in cloned embryos, as the enucleated oocyte does not contain detectable NuMA in the cytoplasm. To determine the source of NuMA in porcine nuclear transfer (NT) embryos, we conducted an immunofluorescence microscopy study with antibodies against NuMA to investigate the appearance and distribution of NuMA before and after reconstructing NT embryos with porcine skin fibroblasts. We used donor cells from a confluent culture with all cells in interphase. For comparative studies, we also determined the immunofluorescence pattern of NuMA, gamma-tubulin, and alpha-tubulin in porcine fibroblasts, parthenogenetic embryos and in vitro fertilized (IVF) embryos. Results show that NuMA was localized in nuclei of 33.5% (163/456) of the serum-deprived fibroblasts used as donor cells. No NuMA staining was detected in enucleated pig oocytes. Immediately after nuclear transfer, NuMA staining was absent in all donor cell fibroblast nuclei (0 h) but staining was detected by 6 h within the reconstructed eggs, at which time the transferred somatic cell nucleus swelled in most cells (19/27) and became a pronucleus-like structure. NuMA was localized exclusively within the pronucleus-like structures (15/27). At 25 h, NuMA was detected inside the nucleus (16/25) either in one-cell or in 2-cell stage embryos. Interestingly, in parthenogenetic embryos, NuMA staining was not detected in all 42 eggs examined at 1 h, and evident NuMA staining was only detected inside a few (4/51 at 6 h; 6/48 at 25 h) of the nuclei. In IVF

  14. Sleep Spindles and Intelligence in Early Childhood--Developmental and Trait-Dependent Aspects

    Science.gov (United States)

    Ujma, Péter P.; Sándor, Piroska; Szakadát, Sára; Gombos, Ferenc; Bódizs, Róbert

    2016-01-01

    Sleep spindles act as a powerful marker of individual differences in cognitive ability. Sleep spindle parameters correlate with both age-related changes in cognitive abilities and with the age-independent concept of IQ. While some studies have specifically demonstrated the relationship between sleep spindles and intelligence in young children, our…

  15. Involvement of Spindles in Memory Consolidation Is Slow Wave Sleep-Specific

    Science.gov (United States)

    Cox, Roy; Hofman, Winni F.; Talamini, Lucia M.

    2012-01-01

    Both sleep spindles and slow oscillations have been implicated in sleep-dependent memory consolidation. Whereas spindles occur during both light and deep sleep, slow oscillations are restricted to deep sleep, raising the possibility of greater consolidation-related spindle involvement during deep sleep. We assessed declarative memory retention…

  16. A yeast strain for simultaneous detection of induced mitotic crossing over, mitotic gene conversion and reverse mutation

    International Nuclear Information System (INIS)

    Zimmermann, F.K.; Kern, R.; Rasenberger, H.

    1975-01-01

    A diploid yeast strain of Saccharomyces cerevisiae is described which can be used to study induction of mitotic crossing-over, mitotic gene conversion and reverse mutation. Mitotic crossing-over can be detected visually as pink and red twin-sectored colonies which are due to the formation of homozygous cells of the genotype ade2-40/ade2-40 (deep red) and ade-2-119/ade2-119 (pink) from the originally heteroallelic condition ade2-40/ade2-119 which forms white colonies. Mitotic gene conversion is monitored by the appearance of tryptophan nonrequiring colonies on selective media. The alleles involved are trp5-12 and trp5-27 derived from the widely used strain D 4 . Mutation induction can be followed by the appearance of isoleucine nonrequiring colonies on selective media. D 7 is homoallelic ilvI-92. The isoleucine requirement caused by ilvI-92 can be alleviated by true reverse mutation and allele non-specific suppressor mutation. The effects of ethyl methanesulfonate (EMS), nitrous acid, ultraviolet light and hycanthone methanesulfonate were studied with D 7 stationary phase cells. Mitotic crossing-over as monitored by red/pink twin-sectored colonies was almost equally frequent among normal and convertant cells. This showed again that nitotic recombination is not due to the presence of a few cells committed to meiosis in an otherwise mitotic cell population. The dose-response curves for induction of mitotic gene conversion and reversion of the isoleucine requirement were exponential. In contrast to this, the dose-response curve for induction of twin sectored red and pink colonies reached a plateau at doses giving about 30% cell killing. This could partly be due to lethal segregation in the progeny of treated cells. None of the agents tested would induce only one type of mitotic recombination, gene conversion or crossing-over. There was, however, some mutagen specificity in the induction of isoleucine prototrophs

  17. Modelling muscle spindle dynamics for a proprioceptive prosthesis.

    Science.gov (United States)

    Williams, Ian; Constandinou, Timothy G

    2013-01-01

    Muscle spindles are found throughout our skeletal muscle tissue and continuously provide us with a sense of our limbs' position and motion (proprioception). This paper advances a model for generating artificial muscle spindle signals for a prosthetic limb, with the aim of one day providing amputees with a sense of feeling in their artificial limb. By utilising the Opensim biomechanical modelling package the relationship between a joint's angle and the length of surrounding muscles is estimated for a prosthetic limb. This is then applied to the established Mileusnic model to determine the associated muscle spindle firing pattern. This complete system model is then reduced to allow for a computationally efficient hardware implementation. This reduction is achieved with minimal impact on accuracy by selecting key mono-articular muscles and fitting equations to relate joint angle to muscle length. Parameter values fitting the Mileusnic model to human spindles are then proposed and validated against previously published human neural recordings. Finally, a model for fusimotor signals is also proposed based on data previously recorded from reduced animal experiments.

  18. A Balance between Nuclear and Cytoplasmic Volumes Controls Spindle Length

    Czech Academy of Sciences Publication Activity Database

    Nováková, Lucia; Kovačovicová, Kristina; Dang-Nguyen, T.; Šodek, Martin; Škultéty, M.; Anger, Martin

    2016-01-01

    Roč. 11, č. 2 (2016), e0149535-e0149535 E-ISSN 1932-6203 R&D Projects: GA ČR GAP502/12/2201 Institutional support: RVO:67985904 Keywords : mitotoc spindle * size * cells Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 2.806, year: 2016

  19. Experimental study on bearing preload optimum of machine tool spindle

    International Nuclear Information System (INIS)

    Xu Tao; Xu Guanghua; Zhang Qin; Hua Cheng; Zhang Hu; Jiang Kuosheng

    2012-01-01

    An experimental study is conducted to investigate the possibility and the effect of temperature rise and vibration level of bearing by adjusting axial preloads and radial loads in spindle bearing test rig. The shaft of the test rig is driven by a motorized high speed spindle at the range of 0∼20000 rpm. The axial preloads and radial loads on bearings are controlled by using hydraulic pressure which can be adjusted automatically. Temperature rise and radial vibration of test bearings are measured by thermocouples and Polytec portable laser vibrometer PDV100. Experiment shows that the temperature rise of bearings is nonlinear varying with the increase of radial loads, but temperature rise almost increases linearly with the increase of axial preload and rotating speed. In this paper, an alternate axial preload is used for bearings. When the rotating speed passes through the critical speed of the shaft, axial preload of bearings will have a remarkable effect. The low preload could reduce bearing vibration and temperature rise for bearings as well. At the others speed, the high preload could improve the vibration performance of high speed spindle and the bearing temperature was lower than that of the constant pressure preload spindle.

  20. Vibration sensitivity of human muscle spindles and Golgi tendon organs.

    Science.gov (United States)

    Fallon, James B; Macefield, Vaughan G

    2007-07-01

    The responses of the various muscle receptors to vibration are more complicated than a naïve categorization into stretch (muscle spindle primary ending), length (muscle spindle secondary endings), and tension (Golgi tendon organs) receptors. To emphasize the similarity of responses to small length changes, we recorded from 58 individual muscle afferents subserving receptors in the ankle or toe dorsiflexors of awake human subjects (32 primary endings, 20 secondary endings, and six Golgi tendon organs). Transverse sinusoidal vibration was applied to the distal tendon of the receptor-bearing muscle, while subjects either remained completely relaxed or maintained a weak isometric contraction of the appropriate muscle. In relaxed muscle, few units responded in a 1:1 manner to vibration, and there was no evidence of a preferred frequency of activation. In active muscle the response profiles of all three receptor types overlapped, with no significant difference in threshold between receptor types. These results emphasize that when intramuscular tension increases during a voluntary contraction, Golgi tendon organs and muscle spindle secondary endings, not just muscle spindle primary endings, can effectively encode small imposed length changes.

  1. Sleep spindle alterations in patients with Parkinson's disease

    DEFF Research Database (Denmark)

    Christensen, Julie Anja Engelhard; Nikolic, Miki; Warby, Simon C.

    2015-01-01

    The aim of this study was to identify changes of sleep spindles (SS) in the EEG of patients with Parkinson's disease (PD). Five sleep experts manually identified SS at a central scalp location (C3-A2) in 15 PD and 15 age- and sex-matched control subjects. Each SS was given a confidence score...

  2. Spindle Oscillations in Sleep Disorders: A Systematic Review

    Directory of Open Access Journals (Sweden)

    Oren M. Weiner

    2016-01-01

    Full Text Available Measurement of sleep microarchitecture and neural oscillations is an increasingly popular technique for quantifying EEG sleep activity. Many studies have examined sleep spindle oscillations in sleep-disordered adults; however reviews of this literature are scarce. As such, our overarching aim was to critically review experimental studies examining sleep spindle activity between adults with and without different sleep disorders. Articles were obtained using a systematic methodology with a priori criteria. Thirty-seven studies meeting final inclusion criteria were reviewed, with studies grouped across three categories: insomnia, hypersomnias, and sleep-related movement disorders (including parasomnias. Studies of patients with insomnia and sleep-disordered breathing were more abundant relative to other diagnoses. All studies were cross-sectional. Studies were largely inconsistent regarding spindle activity differences between clinical and nonclinical groups, with some reporting greater or less activity, while many others reported no group differences. Stark inconsistencies in sample characteristics (e.g., age range and diagnostic criteria and methods of analysis (e.g., spindle bandwidth selection, visual detection versus digital filtering, absolute versus relative spectral power, and NREM2 versus NREM3 suggest a need for greater use of event-based detection methods and increased research standardization. Hypotheses regarding the clinical and empirical implications of these findings, and suggestions for potential future studies, are also discussed.

  3. Discrimination between micronuclei induced by spindle poisons and ...

    African Journals Online (AJOL)

    Discrimination between micronuclei induced by spindle poisons and clastogens by using toad bone marrow polychromatic erythrocytes. ... Egyptian Journal of Biology ... The used chemicals induced high percentages of micronuclei with variable sizes, which clarify the sensitivity of bone marrow cells of Bufo regularis to ...

  4. Spindle assembly checkpoint protein expression correlates with cellular proliferation and shorter time to recurrence in ovarian cancer.

    LENUS (Irish Health Repository)

    McGrogan, Barbara

    2014-07-01

    Ovarian carcinoma (OC) is the most lethal of the gynecological malignancies, often presenting at an advanced stage. Treatment is hampered by high levels of drug resistance. The taxanes are microtubule stabilizing agents, used as first-line agents in the treatment of OC that exert their apoptotic effects through the spindle assembly checkpoint. BUB1-related protein kinase (BUBR1) and mitotic arrest deficient 2 (MAD2), essential spindle assembly checkpoint components, play a key role in response to taxanes. BUBR1, MAD2, and Ki-67 were assessed on an OC tissue microarray platform representing 72 OC tumors of varying histologic subtypes. Sixty-one of these patients received paclitaxel and platinum agents combined; 11 received platinum alone. Overall survival was available for all 72 patients, whereas recurrence-free survival (RFS) was available for 66 patients. Increased BUBR1 expression was seen in serous carcinomas, compared with other histologies (P = .03). Increased BUBR1 was significantly associated with tumors of advanced stage (P = .05). Increased MAD2 and BUBR1 expression also correlated with increased cellular proliferation (P < .0002 and P = .02, respectively). Reduced MAD2 nuclear intensity was associated with a shorter RFS (P = .03), in ovarian tumors of differing histologic subtype (n = 66). In this subgroup, for those women who received paclitaxel and platinum agents combined (n = 57), reduced MAD2 intensity also identified women with a shorter RFS (P < .007). For the entire cohort of patients, irrespective of histologic subtype or treatment, MAD2 nuclear intensity retained independent significance in a multivariate model, with tumors showing reduced nuclear MAD2 intensity identifying patients with a poorer RFS (P = .05).

  5. Identification of Pathways Required for the Coordination of Late Mitotic Events in Animal Cells

    National Research Council Canada - National Science Library

    Baumgartner, Bridget

    2004-01-01

    ... in genomic instability, a hallmark of cancer. In yeast, a signaling pathway has been identified, called the Mitotic Exit Network, which coordinates mitotic exit and cytokinesis with the end of anaphase...

  6. Requirement for PLK1 kinase activity in the maintenance of a robust spindle assembly checkpoint

    Directory of Open Access Journals (Sweden)

    Aisling O'Connor

    2016-01-01

    Full Text Available During mitotic arrest induced by microtubule targeting drugs, the weakening of the spindle assembly checkpoint (SAC allows cells to progress through the cell cycle without chromosome segregation occurring. PLK1 kinase plays a major role in mitosis and emerging evidence indicates that PLK1 is also involved in establishing the checkpoint and maintaining SAC signalling. However, mechanistically, the role of PLK1 in the SAC is not fully understood, with several recent reports indicating that it can cooperate with either one of the major checkpoint kinases, Aurora B or MPS1. In this study, we assess the role of PLK1 in SAC maintenance. We find that in nocodazole-arrested U2OS cells, PLK1 activity is continuously required for maintaining Aurora B protein localisation and activity at kinetochores. Consistent with published data we find that upon PLK1 inhibition, phosphoThr3-H3, a marker of Haspin activity, is reduced. Intriguingly, Aurora B inhibition causes PLK1 to relocalise from kinetochores into fewer and much larger foci, possibly due to incomplete recruitment of outer kinetochore proteins. Importantly, PLK1 inhibition, together with partial inhibition of Aurora B, allows efficient SAC override to occur. This phenotype is more pronounced than the phenotype observed by combining the same PLK1 inhibitors with partial MPS1 inhibition. We also find that PLK1 inhibition does not obviously cooperate with Haspin inhibition to promote SAC override. These results indicate that PLK1 is directly involved in maintaining efficient SAC signalling, possibly by cooperating in a positive feedback loop with Aurora B, and that partially redundant mechanisms exist which reinforce the SAC.

  7. Cdc20 control of cell fate during prolonged mitotic arrest

    DEFF Research Database (Denmark)

    Nilsson, Jakob

    2011-01-01

    The fate of cells arrested in mitosis by antimitotic compounds is complex but is influenced by competition between pathways promoting cell death and pathways promoting mitotic exit. As components of both of these pathways are regulated by Cdc20-dependent degradation, I hypothesize that variations...

  8. Mitotic index studies on edible cocoyams (Xanthosoma and ...

    African Journals Online (AJOL)

    Mitotic index studies were carried out on three cultivars of Xanthosoma and four cultivars of Colocasia. Young healthy roots (about 15 mm) were collected at 2 hourly intervals from 6:00 am to 8:00 pm. Root tips were fixed in 1:3 ethanol : acetic acid for 24 h and stored in 70% ethanol prior to squashing in FLP orcein.

  9. Mitotic Stress in Cancer: Tipping the Fine Balance

    Indian Academy of Sciences (India)

    Acer

    SUSANTA ROYCHOUDHURY. Saroj Gupta Cancer Center and Research Institute. Former, CSIR-Indian Institute of Chemical Biology. Kolkata. Mitotic Stress in Cancer: Tipping the Fine Balance. 81st Annual Meeting,. Indian Academy of Sciences. 6-8 November 2015. IISER, Pune ...

  10. A mitotic transcriptional switch in polycystic kidney disease

    Science.gov (United States)

    Verdeguer, Francisco; Corre, Stephanie Le; Fischer, Evelyne; Callens, Celine; Garbay, Serge; Doyen, Antonia; Igarashi, Peter; Terzi, Fabiola; Pontoglio, Marco

    2011-01-01

    Hepatocyte nuclear factor-1β(HNF-1β) is a transcription factor required for the expression of several renal cystic genes and whose prenatal deletion leads to polycystic kidney disease (PKD)1. We show here that inactivation of Hnf1b from postnatal day 10 onward does not elicit cystic dilations in tubules after their proliferative morphogenetic elongation is over. Cystogenic resistance is intrinsically linked to the quiescent state of cells. In fact, when Hnf1b deficient quiescent cells are forced to proliferate by an ischemiareperfusion injury, they give rise to cysts, owing to loss of oriented cell division. Remarkably, in quiescent cells, the transcription of crucial cystogenic target genes is maintained even in the absence of HNF-1β. However, their expression is lost as soon as cells proliferate and the chromatin of target genes acquires heterochromatin marks. These results unveil a previously undescribed aspect of gene regulation. It is well established that transcription is shut off during the mitotic condensation of chromatin2,3. We propose that transcription factors such as HNF-1β might be involved in reprogramming gene expression after transcriptional silencing is induced by mitotic chromatin condensation. Notably, HNF-1β remains associated with the mitotically condensed chromosomal barrels. This association suggests that HNF-1β is a bookmarking factor that is necessary for reopening the chromatin of target genes after mitotic silencing. PMID:19966811

  11. Coordination of Slow Waves With Sleep Spindles Predicts Sleep-Dependent Memory Consolidation in Schizophrenia.

    Science.gov (United States)

    Demanuele, Charmaine; Bartsch, Ullrich; Baran, Bengi; Khan, Sheraz; Vangel, Mark G; Cox, Roy; Hämäläinen, Matti; Jones, Matthew W; Stickgold, Robert; Manoach, Dara S

    2017-01-01

    Schizophrenia patients have correlated deficits in sleep spindle density and sleep-dependent memory consolidation. In addition to spindle density, memory consolidation is thought to rely on the precise temporal coordination of spindles with slow waves (SWs). We investigated whether this coordination is intact in schizophrenia and its relation to motor procedural memory consolidation. Twenty-one chronic medicated schizophrenia patients and 17 demographically matched healthy controls underwent two nights of polysomnography, with training on the finger tapping motor sequence task (MST) on the second night and testing the following morning. We detected SWs (0.5-4 Hz) and spindles during non-rapid eye movement (NREM) sleep. We measured SW-spindle phase-amplitude coupling and its relation with overnight improvement in MST performance. Patients did not differ from controls in the timing of SW-spindle coupling. In both the groups, spindles peaked during the SW upstate. For patients alone, the later in the SW upstate that spindles peaked and the more reliable this phase relationship, the greater the overnight MST improvement. Regression models that included both spindle density and SW-spindle coordination predicted overnight improvement significantly better than either parameter alone, suggesting that both contribute to memory consolidation. Schizophrenia patients show intact spindle-SW temporal coordination, and these timing relationships, together with spindle density, predict sleep-dependent memory consolidation. These relations were seen only in patients suggesting that their memory is more dependent on optimal spindle-SW timing, possibly due to reduced spindle density. Interventions to improve memory may need to increase spindle density while preserving or enhancing the coordination of NREM oscillations. © Sleep Research Society 2016. Published by Oxford University Press on behalf of the Sleep Research Society. All rights reserved. For permissions, please e

  12. The impact of bipolar depression.

    Science.gov (United States)

    Post, Robert M

    2005-01-01

    Bipolar disorder is a chronic, intermittent illness that is associated with high morbidity and mortality. In addition, patients with bipolar disorder often have comorbid psychiatric conditions (such as anxiety disorders, alcohol or substance abuse, and eating disorders) or medical disorders (such as obesity), which result in increased burden of illness for the patients, family members, and treating clinicians. Although bipolar disorder consists of recurring episodes of mania and depression, patients spend more time depressed than manic. Bipolar depression is associated with a greater risk of suicide and of impairment in work, social, or family life than mania. This health burden also results in direct and indirect economic costs to the individual and society at large. Bipolar depression is often undiagnosed or misdiagnosed as unipolar depression, resulting in incorrect or inadequate treatment. Available treatments for bipolar depression include medications such as lithium, selected anticonvulsants, and the atypical antipsychotics. Traditional antidepressants are not recommended as monotherapy for bipolar depression as they can induce switching to mania. Early and accurate diagnosis, aggressive management, and earlier prophylactic treatment regimens are needed to overcome the impact of depressive episodes in patients with bipolar disorder.

  13. Scientific attitudes towards bipolar disorders

    Directory of Open Access Journals (Sweden)

    Mohammad-Hossein Biglu

    2014-02-01

    Full Text Available Introduction: Bipolar disorder is a psychiatric condition that is also called manic-depressive disease. It causes unusual changes in mood, energy, activity levels, and the ability to carry out day-to-day tasks. In the present study, 3 sets of data were considered and analyzed: first, all papers categorized under Bipolar Disorders in Science Citation Index Expanded (SCI-E database through 2001-2011; second, papers published by the international journal of Bipolar Disorders indexed in SCI-E during a period of 11 years; and third, all papers distributed by the international journal of Bipolar Disorders indexed in MEDLINE during the period of study. Methods: The SCI-E database was used to extract all papers indexed with the topic of Bipolar Disorders as well as all papers published by The International Journal of Bipolar Disorders. Extraction of data from MEDLINE was restricted to the journals name from setting menu. The Science of Science Tool was used to map the co-authorship network of papers published by The International Journal of Bipolar Disorders through 2009-2011. Results: Analysis of data showed that the majority of publications in the subject area of bipolar disorders indexed in SCI-E were published by The International Journal of Bipolar Disorders. Although journal articles consisted of 59% of the total publication type in SCI-E, 65% of publications distributed by The Journal of Bipolar Disorders were in the form of meetingabstracts. Journal articles consisted of only 23% of the total publications. USA was the leading country regarding sharing data in the field of bipolar disorders followed by England, Canada, and Germany. Conclusion: The editorial policy of The International Journal of Bipolar Disorders has been focused on new themes and new ways of researching in the subject area of bipolar disorder. Regarding the selection of papers for indexing, the SCI-E database selects data more comprehensively than MEDLINE. The number of papers

  14. Centrosome Hypertrophy Induced by p53 Mutations Leads to Tumor Aneuploidy

    Science.gov (United States)

    2002-06-01

    nuclear events of the cell cycle in the bodies in tumors displaying apocrine metaplasia, Cen- sea urchin zygote. J Cell Biol 1996, 140:1417-1426 trosome...Images were analyzed and printed as maximum projections. Spindle morphology was scored as normal ’bipolar’ if less than 1% aberrant spindles were...Centrosome function was determined using a quantitative assay for microtubule nucleation and mitotic spindle morphology . The three cell lines can be

  15. Genetics of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Kerner B

    2014-02-01

    Full Text Available Berit Kerner Semel Institute for Neuroscience and Human Behavior, University of California, Los Angeles, Los Angeles, CA, USA Abstract: Bipolar disorder is a common, complex genetic disorder, but the mode of transmission remains to be discovered. Many researchers assume that common genomic variants carry some risk for manifesting the disease. The research community has celebrated the first genome-wide significant associations between common single nucleotide polymorphisms (SNPs and bipolar disorder. Currently, attempts are under way to translate these findings into clinical practice, genetic counseling, and predictive testing. However, some experts remain cautious. After all, common variants explain only a very small percentage of the genetic risk, and functional consequences of the discovered SNPs are inconclusive. Furthermore, the associated SNPs are not disease specific, and the majority of individuals with a “risk” allele are healthy. On the other hand, population-based genome-wide studies in psychiatric disorders have rediscovered rare structural variants and mutations in genes, which were previously known to cause genetic syndromes and monogenic Mendelian disorders. In many Mendelian syndromes, psychiatric symptoms are prevalent. Although these conditions do not fit the classic description of any specific psychiatric disorder, they often show nonspecific psychiatric symptoms that cross diagnostic boundaries, including intellectual disability, behavioral abnormalities, mood disorders, anxiety disorders, attention deficit, impulse control deficit, and psychosis. Although testing for chromosomal disorders and monogenic Mendelian disorders is well established, testing for common variants is still controversial. The standard concept of genetic testing includes at least three broad criteria that need to be fulfilled before new genetic tests should be introduced: analytical validity, clinical validity, and clinical utility. These criteria are

  16. THE INFLUENCE OF CAFFEINE ON MITOTIC DIVISION AT CAPSICUM ANNUUM L.

    Directory of Open Access Journals (Sweden)

    Elena Rosu

    2006-08-01

    Full Text Available The paper presents, the caffeine effects in mitotic division at Capsicum annuum L.. The treatment has determined the lessening of the mitotic index (comparative with the control variant, until mitotic division total inhibition, as well as an growth frequency of division aberation in anaphase and telophase.

  17. Novel multiple criteria decision making methods based on bipolar neutrosophic sets and bipolar neutrosophic graphs

    OpenAIRE

    Muhammad, Akram; Musavarah, Sarwar

    2016-01-01

    In this research study, we introduce the concept of bipolar neutrosophic graphs. We present the dominating and independent sets of bipolar neutrosophic graphs. We describe novel multiple criteria decision making methods based on bipolar neutrosophic sets and bipolar neutrosophic graphs. We also develop an algorithm for computing domination in bipolar neutrosophic graphs.

  18. Spindle Misorientation of Cerebral and Cerebellar Progenitors Is a Mechanistic Cause of Megalencephaly

    Directory of Open Access Journals (Sweden)

    Huaibiao Li

    2017-10-01

    Full Text Available Misoriented division of neuroprogenitors, by loss-of-function studies of centrosome or spindle components, has been linked to the developmental brain defects microcephaly and lissencephaly. As these approaches also affect centrosome biogenesis, spindle assembly, or cell-cycle progression, the resulting pathologies cannot be attributed solely to spindle misorientation. To address this issue, we employed a truncation of the spindle-orienting protein RHAMM. This truncation of the RHAMM centrosome-targeting domain does not have an impact on centrosome biogenesis or on spindle assembly in vivo. The RHAMM mutants exhibit misorientation of the division plane of neuroprogenitors, without affecting the division rate of these cells, resulting against expectation in megalencephaly associated with cerebral cortex thickening, cerebellum enlargement, and premature cerebellum differentiation. We conclude that RHAMM associates with the spindle of neuroprogenitor cells via its centrosome-targeting domain, where it regulates differentiation in the developing brain by orienting the spindle.

  19. Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods

    Directory of Open Access Journals (Sweden)

    Dorothée Coppieters ’t Wallant

    2016-01-01

    Full Text Available Sleep spindle is a peculiar oscillatory brain pattern which has been associated with a number of sleep (isolation from exteroceptive stimuli, memory consolidation and individual characteristics (intellectual quotient. Oddly enough, the definition of a spindle is both incomplete and restrictive. In consequence, there is no consensus about how to detect spindles. Visual scoring is cumbersome and user dependent. To analyze spindle activity in a more robust way, automatic sleep spindle detection methods are essential. Various algorithms were developed, depending on individual research interest, which hampers direct comparisons and meta-analyses. In this review, sleep spindle is first defined physically and topographically. From this general description, we tentatively extract the main characteristics to be detected and analyzed. A nonexhaustive list of automatic spindle detection methods is provided along with a description of their main processing principles. Finally, we propose a technique to assess the detection methods in a robust and comparable way.

  20. Sleep Spindles as an Electrographic Element: Description and Automatic Detection Methods.

    Science.gov (United States)

    Coppieters 't Wallant, Dorothée; Maquet, Pierre; Phillips, Christophe

    2016-01-01

    Sleep spindle is a peculiar oscillatory brain pattern which has been associated with a number of sleep (isolation from exteroceptive stimuli, memory consolidation) and individual characteristics (intellectual quotient). Oddly enough, the definition of a spindle is both incomplete and restrictive. In consequence, there is no consensus about how to detect spindles. Visual scoring is cumbersome and user dependent. To analyze spindle activity in a more robust way, automatic sleep spindle detection methods are essential. Various algorithms were developed, depending on individual research interest, which hampers direct comparisons and meta-analyses. In this review, sleep spindle is first defined physically and topographically. From this general description, we tentatively extract the main characteristics to be detected and analyzed. A nonexhaustive list of automatic spindle detection methods is provided along with a description of their main processing principles. Finally, we propose a technique to assess the detection methods in a robust and comparable way.

  1. Inhibiting Crm1 causes the formation of excess acentriolar spindle poles containing NuMA and B23, but does not affect centrosome numbers.

    Science.gov (United States)

    Rousselet, Annie

    2009-09-14

    B23/nucleophosmin is present on spindle poles at metaphase. Migration of B23 to the poles is under the control of exportin Crm1. B23 at the centrosome plays a role in the control centrosome duplication. h-Tert-RPE1 cells blocked in prometaphase with low doses of Nocodazol showed a progression to mitosis if Crm1 exportin was inhibited. Under these conditions, the formation of accessory poles containing gamma-tubulin, NuMA (nuclear-mitotic-apparatus) and B23 was induced at metaphase. No effect on centrosome number was observed. In quiescent h-Tert-RPE1 cells, when Crm1 was active, B23 was not detected at the centrosome as well as B23-mutants reported to block centrosome duplication. In addition, the modification of B23 nucleo-cytoplasmic shuttling showed no effect on centrosome duplication. Inhibition of Crm1 in early metaphase favours the formation of supplementary acentriolar spindle poles. B23 and NuMA are present at these poles that ultimately focus around the centrosome. Inhibition of Crm1 at metaphase has no effect on the control of centrosome numbers.

  2. Herpes simplex virus induces extensive modification and dynamic relocalisation of the nuclear mitotic apparatus (NuMA) protein in interphase cells.

    Science.gov (United States)

    Yamauchi, Yohei; Kiriyama, Kazuya; Kimura, Hiroshi; Nishiyama, Yukihiro

    2008-06-15

    The nuclear mitotic apparatus (NuMA) protein is a component of the nuclear matrix in interphase cells and an essential protein for the formation of mitotic spindle poles. We used herpes simplex virus (HSV), an enveloped DNA virus that replicates in the nucleus, to study the intra-nuclear dynamics of NuMA in infected cells. This study shows that NuMA is extensively modified following HSV infection, including phosphorylation of an unidentified site(s), and that it depends to an extent on viral DNA synthesis. Although NuMA is insoluble in uninfected interphase cells, HSV infection induced solubilisation and dynamic relocalisation of NuMA, whereupon the protein became excluded from viral replication compartments -- sites of virus transcription and replication. Live cell, confocal imaging showed that NuMA localisation dramatically changed from the early stages (diffusely nuclear, excluding nucleoli) to late stages of infection (central diminuition, but remaining near the inner nuclear peripheries). In addition, NuMA knockdown using siRNA suggested that NuMA is important for efficient viral growth. In summary, we suggest that NuMA is required for efficient HSV infection, and identify further areas of research that address how the virus challenges host cell barriers.

  3. A comparison of two sleep spindle detection methods based on all night averages: individually adjusted versus fixed frequencies

    Directory of Open Access Journals (Sweden)

    Péter Przemyslaw Ujma

    2015-02-01

    Full Text Available Sleep spindles are frequently studied for their relationship with state and trait cognitive variables, and they are thought to play an important role in sleep-related memory consolidation. Due to their frequent occurrence in NREM sleep, the detection of sleep spindles is only feasible using automatic algorithms, of which a large number is available. We compared subject averages of the spindle parameters computed by a fixed frequency (11-13 Hz for slow spindles, 13-15 Hz for fast spindles automatic detection algorithm and the individual adjustment method (IAM, which uses individual frequency bands for sleep spindle detection. Fast spindle duration and amplitude are strongly correlated in the two algorithms, but there is little overlap in fast spindle density and slow spindle parameters in general. The agreement between fixed and manually determined sleep spindle frequencies is limited, especially in case of slow spindles. This is the most likely reason for the poor agreement between the two detection methods in case of slow spindle parameters. Our results suggest that while various algorithms may reliably detect fast spindles, a more sophisticated algorithm primed to individual spindle frequencies is necessary for the detection of slow spindles as well as individual variations in the number of spindles in general.

  4. Bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A.

    2008-10-21

    A bipolar pulse forming transmission line module for linear induction accelerators having first, second, third, fourth, and fifth planar conductors which form an interleaved stack with dielectric layers between the conductors. Each conductor has a first end, and a second end adjacent an acceleration axis. The first and second planar conductors are connected to each other at the second ends, the fourth and fifth planar conductors are connected to each other at the second ends, and the first and fifth planar conductors are connected to each other at the first ends via a shorting plate adjacent the first ends. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short a high voltage from the first end of the third planar conductor to the first end of the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  5. Too much of a good thing? Elevated baseline sleep spindles predict poor avoidance performance in rats.

    Science.gov (United States)

    Fogel, S M; Smith, C T; Beninger, R J

    2010-03-10

    Sleep spindles may be involved in synaptic plasticity. Learning-dependent increases in spindles have been observed in both humans and rats. In humans, the innate (i.e., baseline) number of spindles correlate with measures of academic potential such as Intelligence Quotient (IQ) tests. The present study investigated if spindles predict whether rats are able to learn to make avoidance responses in the two-way shuttle task. Baseline recordings were taken continuously for 24h prior to training on the two-way shuttle task for 50trials/day for two days followed by a 25 trial re-test on the third day. At re-test, rats were categorized into learners (n=16) or non-learners (n=21). Groups did not differ in baseline duration of rapid eye movement sleep, slow wave sleep, wake or spindle density. For combined groups, spindle density in the 21 to 24-hour period but not at any other period during baseline was negatively correlated with shuttle task performance at re-test. Conversely, the learning-related change in spindle density in the 21 to 24-hour period, but not at any other time after the first training session was positively correlated with shuttle task performance. Rats in the non-learning condition have a higher number of spindles at baseline, which is unaffected by training. On the other hand, learning rats have fewer spindles at baseline, but have a learning-related increase in spindles. Extreme spindle activity and high spindle density have been observed in humans with learning disabilities. Results suggest that while spindles may be involved in memory consolidation, in some cases, high levels of spindles prior to training may be maladaptive. Copyright 2010 Elsevier B.V. All rights reserved.

  6. Characterization of Spindle Checkpoint Kinase Mps1 Reveals Domain with Functional and Structural Similarities to Tetratricopeptide Repeat Motifs of Bub1 and BubR1 Checkpoint Kinases*

    Science.gov (United States)

    Lee, Semin; Thebault, Philippe; Freschi, Luca; Beaufils, Sylvie; Blundell, Tom L.; Landry, Christian R.; Bolanos-Garcia, Victor M.; Elowe, Sabine

    2012-01-01

    Kinetochore targeting of the mitotic kinases Bub1, BubR1, and Mps1 has been implicated in efficient execution of their functions in the spindle checkpoint, the self-monitoring system of the eukaryotic cell cycle that ensures chromosome segregation occurs with high fidelity. In all three kinases, kinetochore docking is mediated by the N-terminal region of the protein. Deletions within this region result in checkpoint failure and chromosome segregation defects. Here, we use an interdisciplinary approach that includes biophysical, biochemical, cell biological, and bioinformatics methods to study the N-terminal region of human Mps1. We report the identification of a tandem repeat of the tetratricopeptide repeat (TPR) motif in the N-terminal kinetochore binding region of Mps1, with close homology to the tandem TPR motif of Bub1 and BubR1. Phylogenetic analysis indicates that TPR Mps1 was acquired after the split between deutorostomes and protostomes, as it is distinguishable in chordates and echinoderms. Overexpression of TPR Mps1 resulted in decreased efficiency of both chromosome alignment and mitotic arrest, likely through displacement of endogenous Mps1 from the kinetochore and decreased Mps1 catalytic activity. Taken together, our multidisciplinary strategy provides new insights into the evolution, structural organization, and function of Mps1 N-terminal region. PMID:22187426

  7. Validation of a novel automatic sleep spindle detector with high performance during sleep in middle aged subjects

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Christensen, Julie A. E.; Kempfner, Jacob

    2012-01-01

    Many of the automatic sleep spindle detectors currently used to analyze sleep EEG are either validated on young subjects or not validated thoroughly. The purpose of this study is to develop and validate a fast and reliable sleep spindle detector with high performance in middle aged subjects....... An automatic sleep spindle detector using a bandpass filtering approach and a time varying threshold was developed. The validation was done on sleep epochs from EEG recordings with manually scored sleep spindles from 13 healthy subjects with a mean age of 57.9 ± 9.7 years. The sleep spindle detector reached...... a mean sensitivity of 84.6 % and a mean specificity of 95.3 %. The sleep spindle detector can be used to obtain measures of spindle count and density together with quantitative measures such as the mean spindle frequency, mean spindle amplitude, and mean spindle duration....

  8. Assignment of the nuclear mitotic apparatus protein NuMA gene to human chromosome 11q13

    Energy Technology Data Exchange (ETDEWEB)

    Sparks, C.A.; Bangs, P.L.; Lawrence, J.B.; Fey, E.G.; McNeil, G.P. (Univ. of Massachusetts Medical School, Worcester, MA (United States))

    1993-07-01

    A monoclonal antibody that was specific for a nuclear matrix protein was obtained and used to screen a human [lambda]gt11 expression library. Several partial cDNA clones were isolated and sequenced. The sequence for this protein was shown to be identical to that of NuMA, a 236-kDa nuclear mitotic spindle apparatus protein. NuMA has been recently characterized by two independent studies, and is thought to be part of a family of proteins that is required for the completion of mitosis. In this report, the chromosomal localization and copy number of the NuMA gene are analyzed using cDNA clones. High-resolution in situ hybridization reveals a single pair of signals on sister chromatids of human chromosome 11 at band q13. Stringent Southern analysis of human genomic DNA resulted in simple restriction patterns. These results together indicate that the NuMA gene is present as a single copy on human chromosome 11q13. 12 refs., 1 fig.

  9. Depletion of nuclear import protein karyopherin alpha 7 (KPNA7) induces mitotic defects and deformation of nuclei in cancer cells.

    Science.gov (United States)

    Vuorinen, Elisa M; Rajala, Nina K; Ihalainen, Teemu O; Kallioniemi, Anne

    2018-03-27

    Nucleocytoplasmic transport is a tightly regulated process carried out by specific transport machinery, the defects of which may lead to a number of diseases including cancer. Karyopherin alpha 7 (KPNA7), the newest member of the karyopherin alpha nuclear importer family, is expressed at a high level during embryogenesis, reduced to very low or absent levels in most adult tissues but re-expressed in cancer cells. We used siRNA-based knock-down of KPNA7 in cancer cell lines, followed by functional assays (proliferation and cell cycle) and immunofluorescent stainings to determine the role of KPNA7 in regulation of cancer cell growth, proper mitosis and nuclear morphology. In the present study, we show that the silencing of KPNA7 results in a dramatic reduction in pancreatic and breast cancer cell growth, irrespective of the endogenous KPNA7 expression level. This growth inhibition is accompanied by a decrease in the fraction of S-phase cells as well as aberrant number of centrosomes and severe distortion of the mitotic spindles. In addition, KPNA7 depletion leads to reorganization of lamin A/C and B1, the main nuclear lamina proteins, and drastic alterations in nuclear morphology with lobulated and elongated nuclei. Taken together, our data provide new important evidence on the contribution of KPNA7 to the regulation of cancer cell growth and the maintenance of nuclear envelope environment, and thus deepens our understanding on the impact of nuclear transfer proteins in cancer pathogenesis.

  10. Stability analysis of machine tool spindle under uncertainty

    Directory of Open Access Journals (Sweden)

    Wei Dou

    2016-05-01

    Full Text Available Chatter is a harmful machining vibration that occurs between the workpiece and the cutting tool, usually resulting in irregular flaw streaks on the finished surface and severe tool wear. Stability lobe diagrams could predict chatter by providing graphical representations of the stable combinations of the axial depth of the cut and spindle speed. In this article, the analytical model of a spindle system is constructed, including a Timoshenko beam rotating shaft model and double sets of angular contact ball bearings with 5 degrees of freedom. Then, the stability lobe diagram of the model is developed according to its dynamic properties. The Monte Carlo method is applied to analyse the bearing preload influence on the system stability with uncertainty taken into account.

  11. Radiation-induced spindle cell sarcoma: A rare case report

    Directory of Open Access Journals (Sweden)

    Khan Mubeen

    2009-01-01

    Full Text Available Ionizing radiation has been known to induce malignant transformation in human beings. Radiation-induced sarcomas are a late sequel of radiation therapy. Most sarcomas have been reported to occur after exposure to a radiation dose of 55 Gray (Gy and above, with a dose ranging from 16 to 112 Gys. Spindle cell sarcomas, arising after radiotherapy given to treat the carcinoma of head and neck region is a very uncommon sequel. This is a rare case report of spindle cell sarcoma of left maxilla, in a 24-year-old male, occurring as a late complication of radiotherapy with Cobalt-60 given for the treatment of retinoblastoma of the left eye 21 years back.

  12. Left atrial spindle cell sarcoma – Case report

    Directory of Open Access Journals (Sweden)

    Nihar Mehta

    2012-07-01

    Full Text Available Primary spindle cell sarcoma of the left atrium is an extremely rare tumour. Surgical excision is the mainstay of treatment since it responds poorly to chemotherapy or radiotherapy. In spite of all the treatment, the prognosis remains poor due to inadvertent delay in diagnosis, few therapeutic options and propensity to metastasize. We present a 47-year-old male who underwent a surgical excision of a left atrial mass in February 2010. It was proved to be a high-grade spindle cell sarcoma on histopathology. He presented again in October 2010 with recurrence of the tumour for which he was re-operated. However, the tumour recurred again within one month, to which the patient succumbed.

  13. Asenapine for bipolar disorder

    Directory of Open Access Journals (Sweden)

    Scheidemantel T

    2015-12-01

    Full Text Available Thomas Scheidemantel,1 Irina Korobkova,2 Soham Rej,3,4 Martha Sajatovic1,2 1University Hospitals Case Medical Center, 2Case Western Reserve University School of Medicine, Cleveland, OH, USA; 3Department of Psychiatry, University of Toronto, Toronto, ON, 4Geri PARTy Research Group, Jewish General Hospital, Montreal, QC, Canada Abstract: Asenapine (Saphris® is an atypical antipsychotic drug which has been approved by the US Food and Drug Administration for the treatment of schizophrenia in adults, as well as the treatment of acute manic or mixed episodes of bipolar I in both adult and pediatric populations. Asenapine is a tetracyclic drug with antidopaminergic and antiserotonergic activity with a unique sublingual route of administration. In this review, we examine and summarize the available literature on the safety, efficacy, and tolerability of asenapine in the treatment of bipolar disorder (BD. Data from randomized, double-blind trials comparing asenapine to placebo or olanzapine in the treatment of acute manic or mixed episodes showed asenapine to be an effective monotherapy treatment in clinical settings; asenapine outperformed placebo and showed noninferior performance to olanzapine based on improvement in the Young Mania Rating Scale scores. There are limited data available on the use of asenapine in the treatment of depressive symptoms of BD, or in the maintenance phase of BD. The available data are inconclusive, suggesting the need for more robust data from prospective trials in these clinical domains. The most commonly reported adverse effect associated with use of asenapine is somnolence. However, the somnolence associated with asenapine use did not cause significant rates of discontinuation. While asenapine was associated with weight gain when compared to placebo, it appeared to be modest when compared to other atypical antipsychotics, and its propensity to cause increases in hemoglobin A1c or serum lipid levels appeared to be

  14. The internal Cdc20 binding site in BubR1 facilitates both spindle assembly checkpoint signalling and silencing

    DEFF Research Database (Denmark)

    Lischetti, Tiziana; Zhang, Gang; Sedgwick, Garry G

    2014-01-01

    Improperly attached kinetochores activate the spindle assembly checkpoint (SAC) and by an unknown mechanism catalyse the binding of two checkpoint proteins, Mad2 and BubR1, to Cdc20 forming the mitotic checkpoint complex (MCC). Here, to address the functional role of Cdc20 kinetochore localization...... in the SAC, we delineate the molecular details of its interaction with kinetochores. We find that BubR1 recruits the bulk of Cdc20 to kinetochores through its internal Cdc20 binding domain (IC20BD). We show that preventing Cdc20 kinetochore localization by removal of the IC20BD has a limited effect...... on the SAC because the IC20BD is also required for efficient SAC silencing. Indeed, the IC20BD can disrupt the MCC providing a mechanism for its role in SAC silencing. We thus uncover an unexpected dual function of the second Cdc20 binding site in BubR1 in promoting both efficient SAC signalling and SAC...

  15. Clinical Development of Anti-mitotic Drugs in Cancer.

    Science.gov (United States)

    Olziersky, Anna-Maria; Labidi-Galy, S Intidhar

    2017-01-01

    Mitosis is one of the most fundamental processes of life by which a mammalian cell divides into two daughter cells. Mitosis has been an attractive target for anticancer therapies since fast proliferation was identified as one of the hallmarks of cancer cells. Despite efforts into developing specific inhibitors for mitotic kinases and kinesins, very few drugs have shown the efficiency of microtubule targeting-agents in cancer cells with paclitaxel being the most successful. A deeper translational research accompanying clinical trials of anti-mitotic drugs will help in identifying potent biomarkers predictive for response. Here, we review the current knowledge of mitosis targeting agents that have been tested so far in the clinics.

  16. Bookmarking genes for activation in condensed mitotic chromosomes.

    Science.gov (United States)

    John, S; Workman, J L

    1998-04-01

    A hallmark feature of mitosis is the extinction of bulk cellular transcription. The mechanism by which transcription is abrogated is likely linked to mitotic specific events such as chromosome condensation. Recent studies that probe the structure of genes that can be reactivated rapidly after mitotic repression (early G1) suggest that there are structural distortions in the promoter regions of these genes. These distortions are absent in genes that are typically repressed or reactivated in later phases of the cell cycle (late G1, S, or G2). Such changes in the chromatin structure of these genes may create a transient window for transcription factor binding and rapid reactivation of genes in subsequent phases of the cell cycle.

  17. Architectural Epigenetics: Mitotic Retention of Mammalian Transcriptional Regulatory Information ▿

    Science.gov (United States)

    Zaidi, Sayyed K.; Young, Daniel W.; Montecino, Martin; Lian, Jane B.; Stein, Janet L.; van Wijnen, Andre J.; Stein, Gary S.

    2010-01-01

    Epigenetic regulatory information must be retained during mammalian cell division to sustain phenotype-specific and physiologically responsive gene expression in the progeny cells. Histone modifications, DNA methylation, and RNA-mediated silencing are well-defined epigenetic mechanisms that control the cellular phenotype by regulating gene expression. Recent results suggest that the mitotic retention of nuclease hypersensitivity, selective histone marks, as well as the lineage-specific transcription factor occupancy of promoter elements contribute to the epigenetic control of sustained cellular identity in progeny cells. We propose that these mitotic epigenetic signatures collectively constitute architectural epigenetics, a novel and essential mechanism that conveys regulatory information to sustain the control of phenotype and proliferation in progeny cells by bookmarking genes for activation or suppression. PMID:20696837

  18. Architectural epigenetics: mitotic retention of mammalian transcriptional regulatory information.

    Science.gov (United States)

    Zaidi, Sayyed K; Young, Daniel W; Montecino, Martin; Lian, Jane B; Stein, Janet L; van Wijnen, Andre J; Stein, Gary S

    2010-10-01

    Epigenetic regulatory information must be retained during mammalian cell division to sustain phenotype-specific and physiologically responsive gene expression in the progeny cells. Histone modifications, DNA methylation, and RNA-mediated silencing are well-defined epigenetic mechanisms that control the cellular phenotype by regulating gene expression. Recent results suggest that the mitotic retention of nuclease hypersensitivity, selective histone marks, as well as the lineage-specific transcription factor occupancy of promoter elements contribute to the epigenetic control of sustained cellular identity in progeny cells. We propose that these mitotic epigenetic signatures collectively constitute architectural epigenetics, a novel and essential mechanism that conveys regulatory information to sustain the control of phenotype and proliferation in progeny cells by bookmarking genes for activation or suppression.

  19. Human muscle spindle sensitivity reflects the balance of activity between antagonistic muscles.

    Science.gov (United States)

    Dimitriou, Michael

    2014-10-08

    Muscle spindles are commonly considered as stretch receptors encoding movement, but the functional consequence of their efferent control has remained unclear. The "α-γ coactivation" hypothesis states that activity in a muscle is positively related to the output of its spindle afferents. However, in addition to the above, possible reciprocal inhibition of spindle controllers entails a negative relationship between contractile activity in one muscle and spindle afferent output from its antagonist. By recording spindle afferent responses from alert humans using microneurography, I show that spindle output does reflect antagonistic muscle balance. Specifically, regardless of identical kinematic profiles across active finger movements, stretch of the loaded antagonist muscle (i.e., extensor) was accompanied by increased afferent firing rates from this muscle compared with the baseline case of no constant external load. In contrast, spindle firing rates from the stretching antagonist were lowest when the agonist muscle powering movement (i.e., flexor) acted against an additional resistive load. Stepwise regressions confirmed that instantaneous velocity, extensor, and flexor muscle activity had a significant effect on spindle afferent responses, with flexor activity having a negative effect. Therefore, the results indicate that, as consequence of their efferent control, spindle sensitivity (gain) to muscle stretch reflects the balance of activity between antagonistic muscles rather than only the activity of the spindle-bearing muscle. Copyright © 2014 the authors 0270-6474/14/3413644-12$15.00/0.

  20. Abnormal Nuclear Shape in Solid Tumors Reflects Mitotic Instability

    OpenAIRE

    Gisselsson, David; Björk, Jonas; Höglund, Mattias; Mertens, Fredrik; Dal Cin, Paola; Åkerman, Måns; Mandahl, Nils

    2001-01-01

    Abnormalities in nuclear morphology are frequently observed in malignant tissues but the mechanisms behind these phenomena are still poorly understood. In this study, the relation between abnormal nuclear shape and chromosomal instability was explored in short-term tumor cell cultures. Mitotically unstable ring and dicentric chromosomes were identified by fluorescence in situ hybridization at metaphase and subsequently localized in interphase nuclei from five malignant soft tissue tumors. The...

  1. Mitotic Origins of Chromosomal Instability in Colorectal Cancer

    OpenAIRE

    Dalton, W. Brian; Yang, Vincent W.

    2007-01-01

    Mitosis is a crucial part of the cell cycle. A successful mitosis requires the proper execution of many complex cellular behaviors. Thus, there are many points at which mitosis may be disrupted. In cancer cells, chronic disruption of mitosis can lead to unequal segregation of chromosomes, a phenomenon known as chromosomal instability. A majority of colorectal tumors suffer from this instability, and recent studies have begun to reveal the specific ways in which mitotic defects promote chromos...

  2. Mitotic activity in dorsal epidermis of Rana pipiens.

    Science.gov (United States)

    Garcia-Arce, H.; Mizell, S.

    1972-01-01

    Study of statistically significant rhythms of mitotic division in dorsal epidermis of frogs, Rana pipiens, exposed to a 12:12 light:dark environment for 14 days. The results include the findings that (1) male animals have a primary period of 22 hr in summer and 18 hr in winter, (2) female animals have an 18 hr period, and (3) parapinealectomy and blinding abolish the rhythm.

  3. Oral spindle cell neoplasms: a review of 307 cases.

    Science.gov (United States)

    Jordan, Richard C K; Regezi, Joseph A

    2003-06-01

    The infrequent exposure of pathologists to soft tissue spindle cell neoplasms coupled with overlapping histologic patterns can often make diagnosis challenging. We reviewed all nonodontogenic spindle cell neoplasms seen between 1982 and 2002 (86,162 total accessions). Diagnoses were reclassified according to current standards supplemented with immunohistochemistry. Of the 307 neoplasms reviewed (0.36% of total accessions), neural tumors were the most common benign entities, accounting for 21% of total cases. Kaposi's sarcoma was the most common malignancy, accounting for 67% of all cases. Diagnoses were revised for 57 cases. Schwannoma and neurofibroma were most commonly revised to palisaded encapsulated neuroma. There were 8 myofibromas and 1 inflammatory myofibroblastic tumor. There were no oral leiomyomas; that is, all 4 originally reported cases were reclassified as myofibroma, palisaded encapsulated neuroma, and solitary fibrous tumor. With the exception of Kaposi's sarcoma, oral soft tissue sarcomas were rare; most benign lesions were neural in origin. The relatively high prevalence of some tumors, such as myofibroma, likely reflects the use of immunohistochemistry in the diagnosis of spindle cell tumors.

  4. Ion bipolar junction transistors.

    Science.gov (United States)

    Tybrandt, Klas; Larsson, Karin C; Richter-Dahlfors, Agneta; Berggren, Magnus

    2010-06-01

    Dynamic control of chemical microenvironments is essential for continued development in numerous fields of life sciences. Such control could be achieved with active chemical circuits for delivery of ions and biomolecules. As the basis for such circuitry, we report a solid-state ion bipolar junction transistor (IBJT) based on conducting polymers and thin films of anion- and cation-selective membranes. The IBJT is the ionic analogue to the conventional semiconductor BJT and is manufactured using standard microfabrication techniques. Transistor characteristics along with a model describing the principle of operation, in which an anionic base current amplifies a cationic collector current, are presented. By employing the IBJT as a bioelectronic circuit element for delivery of the neurotransmitter acetylcholine, its efficacy in modulating neuronal cell signaling is demonstrated.

  5. Indirect bipolar electrodeposition.

    Science.gov (United States)

    Loget, Gabriel; Roche, Jérome; Gianessi, Eugenio; Bouffier, Laurent; Kuhn, Alexander

    2012-12-12

    Based on the principles of bipolar electrochemistry, localized pH gradients are generated at the surface of conducting particles in solution. This allows the toposelective deposition of inorganic and organic polymer layers via a pH-triggered precipitation mechanism. Due to the intrinsic symmetry breaking of the process, the concept can be used to generate in a straightforward way Janus particles, with one section consisting of deposits obtained from non-electroactive precursors. These indirect electrodeposits, such as SiO(2), TiO(2), or electrophoretic paints, can be further used as an immobilization matrix for other species like dyes or nanoparticles, thus opening promising perspectives for the synthesis of a variety of bifunctional objects with a controlled shape.

  6. Genetics of bipolar disorder.

    Science.gov (United States)

    Kerner, Berit

    2014-01-01

    Bipolar disorder is a common, complex genetic disorder, but the mode of transmission remains to be discovered. Many researchers assume that common genomic variants carry some risk for manifesting the disease. The research community has celebrated the first genome-wide significant associations between common single nucleotide polymorphisms (SNPs) and bipolar disorder. Currently, attempts are under way to translate these findings into clinical practice, genetic counseling, and predictive testing. However, some experts remain cautious. After all, common variants explain only a very small percentage of the genetic risk, and functional consequences of the discovered SNPs are inconclusive. Furthermore, the associated SNPs are not disease specific, and the majority of individuals with a "risk" allele are healthy. On the other hand, population-based genome-wide studies in psychiatric disorders have rediscovered rare structural variants and mutations in genes, which were previously known to cause genetic syndromes and monogenic Mendelian disorders. In many Mendelian syndromes, psychiatric symptoms are prevalent. Although these conditions do not fit the classic description of any specific psychiatric disorder, they often show nonspecific psychiatric symptoms that cross diagnostic boundaries, including intellectual disability, behavioral abnormalities, mood disorders, anxiety disorders, attention deficit, impulse control deficit, and psychosis. Although testing for chromosomal disorders and monogenic Mendelian disorders is well established, testing for common variants is still controversial. The standard concept of genetic testing includes at least three broad criteria that need to be fulfilled before new genetic tests should be introduced: analytical validity, clinical validity, and clinical utility. These criteria are currently not fulfilled for common genomic variants in psychiatric disorders. Further work is clearly needed before genetic testing for common variants in

  7. Role of senescence and mitotic catastrophe in cancer therapy

    Directory of Open Access Journals (Sweden)

    Shukla Yogeshwer

    2010-01-01

    Full Text Available Abstract Senescence and mitotic catastrophe (MC are two distinct crucial non-apoptotic mechanisms, often triggered in cancer cells and tissues in response to anti-cancer drugs. Chemotherapeuticals and myriad other factors induce cell eradication via these routes. While senescence drives the cells to a state of quiescence, MC drives the cells towards death during the course of mitosis. The senescent phenotype distinguishes tumor cells that survived drug exposure but lost the ability to form colonies from those that recover and proliferate after treatment. Although senescent cells do not proliferate, they are metabolically active and may secrete proteins with potential tumor-promoting activities. The other anti-proliferative response of tumor cells is MC that is a form of cell death that results from abnormal mitosis and leads to the formation of interphase cells with multiple micronuclei. Different classes of cytotoxic agents induce MC, but the pathways of abnormal mitosis differ depending on the nature of the inducer and the status of cell-cycle checkpoints. In this review, we compare the two pathways and mention that they are activated to curb the growth of tumors. Altogether, we have highlighted the possibilities of the use of senescence targeting drugs, mitotic kinases and anti-mitotic agents in fabricating novel strategies in cancer control.

  8. Mitotic Figure Recognition: Agreement among Pathologists and Computerized Detector

    Directory of Open Access Journals (Sweden)

    Christopher Malon

    2012-01-01

    Full Text Available Despite the prognostic importance of mitotic count as one of the components of the Bloom – Richardson grade [3], several studies ([2, 9, 10] have found that pathologists’ agreement on the mitotic grade is fairly modest. Collecting a set of more than 4,200 candidate mitotic figures, we evaluate pathologists' agreement on individual figures, and train a computerized system for mitosis detection, comparing its performance to the classifications of three pathologists. The system’s and the pathologists’ classifications are based on evaluation of digital micrographs of hematoxylin and eosin stained breast tissue. On figures where the majority of pathologists agree on a classification, we compare the performance of the trained system to that of the individual pathologists. We find that the level of agreement of the pathologists ranges from slight to moderate, with strong biases, and that the system performs competitively in rating the ground truth set. This study is a step towards automatic mitosis count to accelerate a pathologist's work and improve reproducibility.

  9. Modeling suicide in bipolar disorders.

    Science.gov (United States)

    Malhi, Gin S; Outhred, Tim; Das, Pritha; Morris, Grace; Hamilton, Amber; Mannie, Zola

    2018-02-19

    Suicide is a multicausal human behavior, with devastating and immensely distressing consequences. Its prevalence is estimated to be 20-30 times greater in patients with bipolar disorders than in the general population. The burden of suicide and its high prevalence in bipolar disorders make it imperative that our current understanding be improved to facilitate prediction of suicide and its prevention. In this review, we provide a new perspective on the process of suicide in bipolar disorder, in the form of a novel integrated model that is derived from extant knowledge and recent evidence. A literature search of articles on suicide in bipolar disorder was conducted in recognized databases such as Scopus, PubMed, and PsycINFO using the keywords "suicide", "suicide in bipolar disorders", "suicide process", "suicide risk", "neurobiology of suicide" and "suicide models". Bibliographies of identified articles were further scrutinized for papers and book chapters of relevance. Risk factors for suicide in bipolar disorders are well described, and provide a basis for a framework of epigenetic mechanisms, moderated by neurobiological substrates, neurocognitive functioning, and social inferences within the environment. Relevant models and theories include the diathesis-stress model, the bipolar model of suicide and the ideation-to-action models, the interpersonal theory of suicide, the integrated motivational-volitional model, and the three-step theory. Together, these models provide a basis for the generation of an integrated model that illuminates the suicidal process, from ideation to action. Suicide is complex, and it is evident that a multidimensional and integrated approach is required to reduce its prevalence. The proposed model exposes and provides access to components of the suicide process that are potentially measurable and may serve as novel and specific therapeutic targets for interventions in the context of bipolar disorder. Thus, this model is useful not only

  10. Spindle assembly checkpoint signalling is uncoupled from chromosomal position in mouse oocytes.

    Science.gov (United States)

    Gui, Liming; Homer, Hayden

    2012-06-01

    The spindle assembly checkpoint (SAC) averts aneuploidy by coordinating proper bipolar chromosomal attachment with anaphase-promoting complex/cyclosome (APC/C)-mediated securin and cyclin B1 destruction required for anaphase onset. The generation of a Mad2-based signal at kinetochores is central to current models of SAC-based APC/C inhibition. During mitosis, kinetochores of polar-displaced chromosomes, which are at greatest risk of mis-segregating, recruit the highest levels of Mad2, thereby ensuring that SAC activation is proportionate to aneuploidy risk. Paradoxically, although an SAC operates in mammalian oocytes, meiosis I (MI) is notoriously error prone and polar-displaced chromosomes do not prevent anaphase onset. Here we find that Mad2 is not preferentially recruited to the kinetochores of polar chromosomes of wild-type mouse oocytes, in which polar chromosomes are rare, or of oocytes depleted of the kinesin-7 motor CENP-E, in which polar chromosomes are more abundant. Furthermore, in CENP-E-depleted oocytes, although polar chromosomal displacement intensified during MI and the capacity to form stable end-on attachments was severely compromised, all kinetochores nevertheless became devoid of Mad2. Thus, it is possible that the ability of the SAC to robustly discriminate chromosomal position might be compromised by the propensity of oocyte kinetochores to become saturated with unproductive attachments, thereby predisposing to aneuploidy. Our data also reveal novel functions for CENP-E in oocytes: first, CENP-E stabilises BubR1, thereby impacting MI progression; and second, CENP-E mediates bi-orientation by promoting kinetochore reorientation and preventing chromosomal drift towards the poles.

  11. Prognostic importance of the mitotic marker phosphohistone H3 in cutaneous nodular melanoma.

    Science.gov (United States)

    Ladstein, Rita G; Bachmann, Ingeborg M; Straume, Oddbjørn; Akslen, Lars A

    2012-04-01

    Mitotic count is a known prognostic predictor in cutaneous melanoma, and is included in the current American Joint Committee on Cancer tumor-node-metastasis (TNM) staging system. The mitotic marker phosphohistone H3 (PHH3) is considered to facilitate counting of mitosis, and the purpose of this study was to evaluate the prognostic significance and strength of PHH3 in comparison with standard mitotic counting in cutaneous malignant melanoma. A total of 457 consecutive cases of nodular cutaneous melanoma were initially included in this series. The mitotic count was assessed on hematoxylin and eosin sections, and PHH3 was then examined by immunohistochemistry on standard sections of paraffin-embedded tumor tissue. Both the mitotic count and the number of PHH3-stained mitotic figures were recorded in a minimum area of 1 mm(2). Increased mitotic count and PHH3 value were both associated with unfavorable features like tumor thickness and presence of ulceration. Univariate survival analysis showed a highly significant prognostic impact of mitotic count and PHH3, whereas multivariate analysis indicated PHH3 to be a stronger prognostic indicator than mitotic count. Assessment of mitotic activity by PHH3 immunostaining might have important practical advantages, and should be further studied to consider a place in routine examination of all cutaneous melanomas.

  12. Inter-expert and intra-expert reliability in sleep spindle scoring

    DEFF Research Database (Denmark)

    Wendt, Sabrina Lyngbye; Welinder, Peter; Sørensen, Helge Bjarup Dissing

    2015-01-01

    with higher reliability than the estimation of spindle duration. Reliability of sleep spindle scoring can be improved by using qualitative confidence scores, rather than a dichotomous yes/no scoring system. Conclusions We estimate that 2–3 experts are needed to build a spindle scoring dataset......Objectives To measure the inter-expert and intra-expert agreement in sleep spindle scoring, and to quantify how many experts are needed to build a reliable dataset of sleep spindle scorings. Methods The EEG dataset was comprised of 400 randomly selected 115 s segments of stage 2 sleep from 110...... sleeping subjects in the general population (57 ± 8, range: 42–72 years). To assess expert agreement, a total of 24 Registered Polysomnographic Technologists (RPSGTs) scored spindles in a subset of the EEG dataset at a single electrode location (C3-M2). Intra-expert and inter-expert agreements were...

  13. Magnetic suspension motorized spindle-cutting system dynamics analysis and vibration control review

    Directory of Open Access Journals (Sweden)

    Xiaoli QIAO

    2016-10-01

    Full Text Available The performance of high-speed spindle directly determines the development of high-end machine tools. The cutting system's dynamic characteristics and vibration control effect are inseparable with the performance of the spindle,which influence each other, synergistic effect together the cutting efficiency, the surface quality of the workpiece and tool life in machining process. So, the review status on magnetic suspension motorized spindle, magnetic suspension bearing-flexible rotor system dynamics modeling theory and status of active control technology of flexible magnetic suspension motorized spindle rotor vibration are studied, and the problems which present in the magnetic suspension flexible motorized spindle rotor systems are refined, and the development trend of magnetic levitation motorized spindle and the application prospect is forecasted.

  14. Optimal design of high-speed loading spindle based on ABAQUS

    Science.gov (United States)

    Yang, Xudong; Dong, Yu; Ge, Qingkuan; Yang, Hai

    2017-12-01

    The three-dimensional model of high-speed loading spindle is established by using ABAQUS’s modeling module. A finite element analysis model of high-speed loading spindle was established by using spring element to simulate bearing boundary condition. The static and dynamic performance of the spindle structure with different specifications of the rectangular spline and the different diameter neck of axle are studied in depth, and the influence of different spindle span on the static and dynamic performance of the high-speed loading spindle is studied. Finally, the optimal structure of the high-speed loading spindle is obtained. The results provide a theoretical basis for improving the overall performance of the test-bed

  15. Quetiapine monotherapy for bipolar depression

    Directory of Open Access Journals (Sweden)

    Michael E Thase

    2008-03-01

    Full Text Available Michael E ThaseDepartments of Psychiatry, University of Pennsylvania School of Medicine, Philadelphia, PA, USA; the Philadelphia Veterans Affairs Medical Center, Philadelphia, PA, USA; and the University of Pittsburgh Medical Center, Pittsburgh, PA, USAAbstract: Bipolar depression is more common, disabling, and difficult-to-treat than the manic and hypomanic phases that define bipolar disorder. Unlike the treatment of so-called “unipolar” depressions, antidepressants generally are not indicated as monotherapies for bipolar depressions and recent studies suggest that - even when used in combination with traditional mood stabilizers – antidepressants may have questionable value for bipolar depression. The current practice is that mood stabilizers are initiated first as monotherapies; however, the antidepressant efficacy of lithium and valproate is modest at best. Within this context the role of atypical antipsychotics is being evaluated. The combination of olanzapine and the antidepressant fluoxetine was the first treatment to receive regulatory approval in the US specifically for bipolar I depression. Quetiapine was the second medication to be approved for this indication, largely as the result of two pivotal trials known by the acronyms of BOLDER (BipOLar DEpRession I and II. Both studies demonstrated that two doses of quetiapine (300 mg and 600 mg given once daily at bedtime were significantly more effective than placebo, with no increased risk of patients switching into mania. Pooling the two studies, quetiapine was effective for both bipolar I and bipolar II depressions and for patients with (and without a history of rapid cycling. The two doses were comparably effective in both studies. Although the efficacy of quetiapine monotherapy has been established, much additional research is necessary. Further studies are needed to more fully investigate dose-response relationships and comparing quetiapine monotherapy to other mood stabilizers

  16. S100A6 and c-Kit-Positive Spindle Cell Melanoma of the Dorsal Foot

    Directory of Open Access Journals (Sweden)

    Yasutaka Mitamura

    2014-05-01

    Full Text Available Spindle cell melanoma, which is a rare form of melanoma, is clinically and histopathologically difficult to diagnose from a variety of nonmelanocytic spindle cell tumors. We describe a 42-year-old Japanese woman with amelanotic melanoma that comprised spindle cells with positive c-kit and S100A6 staining. The use of c-kit and S100A6 might be useful for improving the diagnosis.

  17. Spindle and Giant Cell Type Undifferentiated Carcinoma of the Proximal Bile Duct

    OpenAIRE

    Ide, Takao; Miyoshi, Atsushi; Kitahara, Kenji; Kai, Keita; Noshiro, Hirokazu

    2012-01-01

    Undifferentiated spindle and giant cell carcinoma is an extremely rare malignant neoplasm arising in the extrahepatic bile duct. We herein present the case of a 67-year-old male who developed an undifferentiated spindle and giant cell carcinoma of the proximal bile duct. A nodular infiltrating tumor was located at the proximal bile duct, resulting in obstructive jaundice. Histologically, the tumor was composed of mainly spindle-shaped and giant cells and showed positive immunoreactivity for b...

  18. A potential tension-sensing mechanism that ensures timely anaphase onset upon metaphase spindle orientation.

    Science.gov (United States)

    Rajagopalan, Srividya; Bimbo, Andrea; Balasubramanian, Mohan K; Oliferenko, Snezhana

    2004-01-06

    The spindle orientation checkpoint (SOC) in fission yeast has been proposed to delay metaphase-to-anaphase transition when the spindle poles are misaligned with respect to the long axis of the cell. This checkpoint is activated in the absence of either an actomyosin division ring or astral microtubules. Although the SOC could be overridden in the absence of the transcription factor Atf1p, its mechanistic nature remained unclear. Here, we show that the SOC-triggered metaphase delay depends on a subset of the spindle assembly checkpoint (SAC) components Mph1p and Bub1p. Based on this finding and a detailed imaging of the spindle orientation process, we hypothesized that the spindle pole might contain proteins capable of sensing the achievement of spindle alignment. We identified the kendrin-like spindle pole body resident Pcp1p as a candidate molecule. A targeted mutation in its central domain specifically triggered the SOC in spite of the presence of oriented spindles, causing a metaphase delay that could be relieved in the absence of Mph1p, Bub1p, and Atf1p. Thus, Pcp1p might provide a link between the mechanical process of spindle alignment and the signal transduction that initiates anaphase.

  19. A further observation of muscle spindles in the extensor digitorum longus muscle of the aged rat.

    Science.gov (United States)

    Desaki, Junzo; Nishida, Naoya

    2010-01-01

    We observed three novel muscle spindles in the extensor digitorum longus muscle of the aged (20 months) rat. Two muscle spindles of the three contained thin muscle fibers lacking sensory innervation between the layers of the spindle capsule and within the periaxial space, respectively. The other one contained sensory-innervated thin muscle fibers with an indistinct equatorial nucleation between the layers of the spindle capsule. These findings suggest that the occurrence of thin muscle fibers may be intimately related to the degeneration and regeneration of extrafusal muscle fibers during aging and that these newly formed thin muscle fibers may often fail to receive sensory innervation.

  20. REM sleep behaviour disorder is associated with lower fast and higher slow sleep spindle densities.

    Science.gov (United States)

    O'Reilly, Christian; Godin, Isabelle; Montplaisir, Jacques; Nielsen, Tore

    2015-12-01

    To investigate differences in sleep spindle properties and scalp topography between patients with rapid eye movement sleep behaviour disorder (RBD) and healthy controls, whole-night polysomnograms of 35 patients diagnosed with RBD and 35 healthy control subjects matched for age and sex were compared. Recordings included a 19-lead 10-20 electroencephalogram montage and standard electromyogram, electrooculogram, electrocardiogram and respiratory leads. Sleep spindles were automatically detected using a standard algorithm, and their characteristics (amplitude, duration, density, frequency and frequency slope) compared between groups. Topological analyses of group-discriminative features were conducted. Sleep spindles occurred at a significantly (e.g. t34 = -4.49; P = 0.00008 for C3) lower density (spindles ∙ min(-1) ) for RBD (mean ± SD: 1.61 ± 0.56 for C3) than for control (2.19 ± 0.61 for C3) participants. However, when distinguishing slow and fast spindles using thresholds individually adapted to the electroencephalogram spectrum of each participant, densities smaller (31-96%) for fast but larger (20-120%) for slow spindles were observed in RBD in all derivations. Maximal differences were in more posterior regions for slow spindles, but over the entire scalp for fast spindles. Results suggest that the density of sleep spindles is altered in patients with RBD and should therefore be investigated as a potential marker of future neurodegeneration in these patients. © 2015 European Sleep Research Society.

  1. Dynamic behavior of the horizontal milling and drilling machine spindle assembly with Dynrot software

    Directory of Open Access Journals (Sweden)

    Căruţaşu Nicoleta Luminiţa

    2017-01-01

    Full Text Available This article presents research conducted to study the dynamic behavior of the assembly of a horizontal milling CNC machine spindle at the speed of 10 000 rpm and 50 000 rpm. This step aims to determine the critical rotation speeds of the complex system “spindle – bearings”, by drawing Campbell diagrams. The rotor is a subset of these machines, consisting of a shaft, in which the one or more discs, and which executes a rotating motion around the axis propyl. The curve Campbell contours in the diagram represents the variation of natural pulsations of spindle system, depending on the speed bearing spindle.

  2. Integrated neurobiology of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Vladimir eMaletic

    2014-08-01

    Full Text Available From a neurobiological perspective there is no such thing as bipolar disorder. Rather, it is almost certainly the case that many somewhat similar, but subtly different, pathological conditions produce a disease state that we currently diagnose as bipolarity. This heterogeneity—reflected in the lack of synergy between our current diagnostic schema and our rapidly advancing scientific understanding of the condition—limits attempts to articulate an integrated perspective on bipolar disorder. However, despite these challenges, scientific findings in recent years are beginning to offer a provisional unified field theory of the disease. This theory sees bipolar disorder as a suite of related neurodevelopmental conditions with interconnected functional abnormalities that often appear early in life and worsen over time. In addition to accelerated loss of volume in brain areas known to be essential for mood regulation and cognitive function, consistent findings have emerged at a cellular level, providing evidence that bipolar disorder is reliably associated with dysregulation of glial-neuronal interactions. Among these glial elements are microglia—the brain’s primary immune elements, which appear to be overactive in the context of bipolarity. Multiple studies now indicate that inflammation is also increased in the periphery of the body in both the depressive and manic phases of the illness, with at least some return to normality in the euthymic state. These findings are consistent with changes in the HPA axis, which are known to drive inflammatory activation. In summary, the very fact that no single gene, pathway or brain abnormality is likely to ever account for the condition is itself an extremely important first step in better articulating an integrated perspective on both its ontological status and pathogenesis. Whether this perspective will translate into the discovery of innumerable more homogeneous forms of bipolarity is one of the great

  3. [Genetics of bipolar disorder].

    Science.gov (United States)

    Budde, M; Forstner, A J; Adorjan, K; Schaupp, S K; Nöthen, M M; Schulze, T G

    2017-07-01

    Bipolar disorder (BD) has a multifactorial etiology. Its development is influenced by genetic as well as environmental factors. Large genome-wide association studies (GWAS), in which genetic risk allelic variants for the disorder could be replicated for the first time, marked the breakthrough in the identification of the responsible risk genes. In addition to these common genetic variants with moderate effects identified by GWAS, rare variants with a higher penetrance are expected to play a role in disease development. The results of recent studies suggest that copy number variants might contribute to BD development, although to a lesser extent than in other psychiatric disorders, such as schizophrenia or autism. Results from the initial next generation sequencing studies indicate an enrichment of rare variants in pathways and genes that were previously found to be associated with BD. In the field of pharmacogenetics, a risk gene that influences the individual variance in the response to lithium treatment was identified for the first time in a recent large international GWAS. Currently the reported risk alleles do not sufficiently explain the phenotypic variance to be used for individual prediction of disease risk, disease course or response to medication. Future genetic research will provide important insights into the biological basis of BD by the identification of additional genes associated with BD. This knowledge of genetics will help identify potential etiological subgroups as well as cross-diagnostic disease mechanisms.

  4. Bipolar Disorder in Children and Teens

    Science.gov (United States)

    ... I do? Share Bipolar Disorder in Children and Teens Download PDF Download ePub Order a free hardcopy ... Think about death or suicide Can children and teens with bipolar disorder have other problems? Young people ...

  5. Daytime naps, motor memory consolidation and regionally specific sleep spindles.

    Directory of Open Access Journals (Sweden)

    Masaki Nishida

    Full Text Available BACKGROUND: Increasing evidence demonstrates that motor-skill memories improve across a night of sleep, and that non-rapid eye movement (NREM sleep commonly plays a role in orchestrating these consolidation enhancements. Here we show the benefit of a daytime nap on motor memory consolidation and its relationship not simply with global sleep-stage measures, but unique characteristics of sleep spindles at regionally specific locations; mapping to the corresponding memory representation. METHODOLOGY/PRINCIPAL FINDINGS: Two groups of subjects trained on a motor-skill task using their left hand - a paradigm known to result in overnight plastic changes in the contralateral, right motor cortex. Both groups trained in the morning and were tested 8 hr later, with one group obtaining a 60-90 minute intervening midday nap, while the other group remained awake. At testing, subjects that did not nap showed no significant performance improvement, yet those that did nap expressed a highly significant consolidation enhancement. Within the nap group, the amount of offline improvement showed a significant correlation with the global measure of stage-2 NREM sleep. However, topographical sleep spindle analysis revealed more precise correlations. Specifically, when spindle activity at the central electrode of the non-learning hemisphere (left was subtracted from that in the learning hemisphere (right, representing the homeostatic difference following learning, strong positive relationships with offline memory improvement emerged-correlations that were not evident for either hemisphere alone. CONCLUSIONS/SIGNIFICANCE: These results demonstrate that motor memories are dynamically facilitated across daytime naps, enhancements that are uniquely associated with electrophysiological events expressed at local, anatomically discrete locations of the brain.

  6. Mitotic delay of irradiated cells and its connection with quantity of radiation injuries

    International Nuclear Information System (INIS)

    Lobachevskij, P.N.; Fominykh, E.V.

    1989-01-01

    The study is dedicated to development of mathematical approach to interpret radiation-induced mitosic delay. An assumption is made that mitotic delay is conditioned by discrete injuries distributed in cells according to stochasticity of interaction of radiation and target substance. It is supposed to consider the problem on injuries nature causing mitotic delay and to use the developed method for accounting the effect of radiation-induced mitotic delay on registered chromosomal aberration yield. 10 refs.; 2 figs.; 3 tabs

  7. Exercising control over bipolar disorder.

    Science.gov (United States)

    Malhi, Gin S; Byrow, Yulisha

    2016-11-01

    Following extensive research exercise has emerged as an effective treatment for major depressive disorder, and it is now a recognised therapy alongside other interventions. In contrast, there is a paucity of research examining the therapeutic effects of exercise for those with bipolar disorder. Given that dysfunctional reward processing is central to bipolar disorder, research suggests that exercise can perhaps be framed as a reward-related event that may have the potential to precipitate a manic episode. The behavioural activation system (BAS) is a neurobehavioural system that is associated with responding to reward and provides an appropriate framework to theoretically examine and better understand the effects of exercise treatment on bipolar disorder. This article discusses recent research findings and provides an overview of the extant literature related to the neurobiological underpinnings of BAS and exercise as they relate to bipolar disorder. This is important clinically because depending on mood state in bipolar disorder, we postulate that exercise could be either beneficial or deleterious with positive or negative effects on the illness. Clearly, this complicates the evaluation of exercise as a potential treatment in terms of identifying its optimal characteristics in this population. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

  8. Imunologia do transtorno bipolar Immunology of bipolar disorder

    Directory of Open Access Journals (Sweden)

    Izabela Guimarães Barbosa

    2009-01-01

    Full Text Available OBJETIVO: Pesquisas recentes têm implicado fatores imunes na patogênese de diversos transtornos neuropsiquiátricos. O objetivo do presente trabalho é revisar os trabalhos que investigaram a associação entre transtorno bipolar e alterações em parâmetros imunes. MÉTODOS: Artigos que incluíam as palavras-chave: "bipolar disorder", "mania", "immunology", "cytokines", "chemokines", "interleukins", "interferon" e "tumor necrosis factor" foram selecionados em uma revisão sistemática da literatura. As bases de dados avaliadas foram MedLine e Scopus, entre os anos de 1980 e 2008. RESULTADOS: Foram identificados 28 trabalhos que estudaram alterações imunes em pacientes com transtorno bipolar. Seis artigos investigaram genes relacionados à resposta imune; cinco, autoanticorpos; quatro, populações leucocitárias; 13, citocinas e/ou moléculas relacionadas à resposta imune e seis, leucócitos de pacientes in vitro. CONCLUSÕES: Embora haja evidências na literatura correlacionando o transtorno bipolar a alterações imunes, os dados não são conclusivos. O transtorno bipolar parece estar associado a níveis mais elevados de autoanticorpos circulantes, assim como à tendência à ativação imune com produção de citocinas pró-inflamatórias e redução de parâmetros anti-inflamatórios.OBJECTIVE: Emerging research has implicated immune factors in the pathogenesis of a variety of neuropsychiatric disorders. The objective of the present paper is to review the studies that investigated the association between bipolar disorder and immune parameters. METHODS: Papers that included the keywords "bipolar to disorder", "mania", "immunology", "cytokines", "chemokines", "interleukins", "interferon" and "tumor necrosis factor" were selected in a systematic review of the literature. The evaluated databases were MedLine and Scopus in the period between 1980 and 2008. RESULTS: Twenty eight works were found. Six studies investigated immune response

  9. Sleep Spindle Detection and Prediction Using a Mixture of Time Series and Chaotic Features

    Directory of Open Access Journals (Sweden)

    Amin Hekmatmanesh

    2017-01-01

    Full Text Available It is well established that sleep spindles (bursts of oscillatory brain electrical activity are significant indicators of learning, memory and some disease states. Therefore, many attempts have been made to detect these hallmark patterns automatically. In this pilot investigation, we paid special attention to nonlinear chaotic features of EEG signals (in combination with linear features to investigate the detection and prediction of sleep spindles. These nonlinear features included: Higuchi's, Katz's and Sevcik's Fractal Dimensions, as well as the Largest Lyapunov Exponent and Kolmogorov's Entropy. It was shown that the intensity map of various nonlinear features derived from the constructive interference of spindle signals could improve the detection of the sleep spindles. It was also observed that the prediction of sleep spindles could be facilitated by means of the analysis of these maps. Two well-known classifiers, namely the Multi-Layer Perceptron (MLP and the K-Nearest Neighbor (KNN were used to distinguish between spindle and non-spindle patterns. The MLP classifier produced a~high discriminative capacity (accuracy = 94.93%, sensitivity = 94.31% and specificity = 95.28% with significant robustness (accuracy ranging from 91.33% to 94.93%, sensitivity varying from 91.20% to 94.31%, and specificity extending from 89.79% to 95.28% in separating spindles from non-spindles. This classifier also generated the best results in predicting sleep spindles based on chaotic features. In addition, the MLP was used to find out the best time window for predicting the sleep spindles, with the experimental results reaching 97.96% accuracy.

  10. Sequential multisite phospho-regulation of KNL1-BUB3 interfaces at mitotic kinetochores

    NARCIS (Netherlands)

    Vleugel, Mathijs; Omerzu, Manja; Groenewold, Vincent; Hadders, Michael A; Lens, Susanne M A; Kops, Geert J P L

    2015-01-01

    Regulated recruitment of the kinase-adaptor complex BUB1/BUB3 to kinetochores is crucial for correcting faulty chromosome-spindle attachments and for spindle assembly checkpoint (SAC) signaling. BUB1/BUB3 localizes to kinetochores by binding phosphorylated MELT motifs (MELpT) in the kinetochore

  11. Mathematical models of bipolar disorder

    Science.gov (United States)

    Daugherty, Darryl; Roque-Urrea, Tairi; Urrea-Roque, John; Troyer, Jessica; Wirkus, Stephen; Porter, Mason A.

    2009-07-01

    We use limit cycle oscillators to model bipolar II disorder, which is characterized by alternating hypomanic and depressive episodes and afflicts about 1% of the United States adult population. We consider two non-linear oscillator models of a single bipolar patient. In both frameworks, we begin with an untreated individual and examine the mathematical effects and resulting biological consequences of treatment. We also briefly consider the dynamics of interacting bipolar II individuals using weakly-coupled, weakly-damped harmonic oscillators. We discuss how the proposed models can be used as a framework for refined models that incorporate additional biological data. We conclude with a discussion of possible generalizations of our work, as there are several biologically-motivated extensions that can be readily incorporated into the series of models presented here.

  12. Lateralised sleep spindles relate to false memory generation.

    Science.gov (United States)

    Shaw, John J; Monaghan, Padraic

    2017-12-01

    Sleep is known to enhance false memories: After presenting participants with lists of semantically related words, sleeping before recalling these words results in a greater acceptance of unseen "lure" words related in theme to previously seen words. Furthermore, the right hemisphere (RH) seems to be more prone to false memories than the left hemisphere (LH). In the current study, we investigated the sleep architecture associated with these false memory and lateralisation effects in a nap study. Participants viewed lists of related words, then stayed awake or slept for approximately 90min, and were then tested for recognition of previously seen-old, unseen-new, or unseen-lure words presented either to the LH or RH. Sleep increased acceptance of unseen-lure words as previously seen compared to the wake group, particularly for RH presentations of word lists. RH lateralised stage 2 sleep spindle density relative to the LH correlated with this increase in false memories, suggesting that RH sleep spindles enhanced false memories in the RH. Copyright © 2017 Elsevier Ltd. All rights reserved.

  13. Loops determine the mechanical properties of mitotic chromosomes.

    Directory of Open Access Journals (Sweden)

    Yang Zhang

    Full Text Available We introduce a new polymer model for mitotic chromosomes. The key assumption of the model is the ability of the chromatin fibre to cross-link to itself due to binding proteins. These protein-chromatin interactions are included by a probabilistic and dynamic mechanism. The hypothesis is motivated by the observation of high repulsive forces between ring polymers. We performed computer simulations to validate our model. Our results show that the presence of loops leads to a tight compaction and contributes significantly to the bending rigidity of chromosomes. Moreover, our qualitative prediction of the force elongation behaviour is close to experimental findings. The Dynamic Loop Model presented here indicates that the internal structure of mitotic chromosomes is based on self-organization of the chromatin fibre rather than attachment of chromatin to a protein scaffold. It also shows that the number and size of loops have a strong influence on the mechanical properties. We suggest that changes in the mechanical characteristics of chromosomes in different stages of the cell cycle, for example, can be explained by an altered internal loop structure.

  14. Inhibition of mitotic-specific histone phophorylation by sodium arsenite

    Energy Technology Data Exchange (ETDEWEB)

    Cobo, J.M. [Universidad de Alcala de Henares, Madrid (Spain); Valdez, J.G.; Gurley, L.R. [Los Alamos National Lab., NM (United States)

    1994-10-01

    Synchronized cultures of Chinese hamster cells (line CHO) were used to measure the effects of 10{mu}M sodium arsenite on histone phosphorylation. This treatment caused cell proliferation to be temporarily arrested, after which the cells spontaneously resumed cell proliferation in a radiomimetric manner. Immediately following treatment, it was found that sodium arsenite affected only mitotic-specific HI and H3 phosphorylations. Neither interphase, nor mitotic, H2A and H4 phosphorylations were affected, nor was interphase HI Phosphorylation affected. The phosphorylation of HI was inhibited only in mitosis, reducing HI phosphorylation to 38.1% of control levels, which was the level of interphase HI phosphorylation. The phosphorylation of both H3 variants was inhibited in mitosis, the less hydrophobic H3 to 19% and the more hydrophobic H3 to 24% of control levels. These results suggest that sodium arsenite may inhibite cell proliferation by interfering with the cyclin B/p34{sup cdc2} histone kinase activity which is thought to play a key role in regulating the cell cycle. It has been proposed by our laboratory that HI and H3 phosphorylations play a role in restructuring interphase chromatin into metaphase chromosomes. Interference of this process by sodium arsenite may lead to structurally damaged chromosomes resulting in the increased cancer risks known to be produced by arsenic exposure from the environment.

  15. Transcultural aspects of bipolar disorder

    OpenAIRE

    Sanches, Marsal; Jorge, Miguel Roberto

    2004-01-01

    Considerando-se que existem diferenças importantes na maneira como as emoções são vivenciadas e expressas em diferentes culturas, a apresentação e o manejo do transtorno afetivo bipolar sofrem influência de fatores culturais. O presente artigo realiza uma breve revisão da evidência referente aos aspectos transculturais do transtorno bipolar.Cultural variations in the expression of emotions have been described. Consequently, there are cross-cultural influences on the diagnosis and management o...

  16. Slow sleep spindle activity, declarative memory, and general cognitive abilities in children.

    Science.gov (United States)

    Hoedlmoser, Kerstin; Heib, Dominik P J; Roell, Judith; Peigneux, Philippe; Sadeh, Avi; Gruber, Georg; Schabus, Manuel

    2014-09-01

    Functional interactions between sleep spindle activity, declarative memory consolidation, and general cognitive abilities in school-aged children. Healthy, prepubertal children (n = 63; mean age 9.56 ± 0.76 y); ambulatory all-night polysomnography (2 nights); investigating the effect of prior learning (word pair association task; experimental night) versus nonlearning (baseline night) on sleep spindle activity; general cognitive abilities assessed using the Wechsler Intelligence Scale for Children-IV (WISC-IV). Analysis of spindle activity during nonrapid eye movement sleep (N2 and N3) evidenced predominant peaks in the slow (11-13 Hz) but not in the fast (13-15 Hz) sleep spindle frequency range (baseline and experimental night). Analyses were restricted to slow sleep spindles. Changes in spindle activity from the baseline to the experimental night were not associated with the overnight change in the number of recalled words reflecting declarative memory consolidation. Children with higher sleep spindle activity as measured at frontal, central, parietal, and occipital sites during both baseline and experimental nights exhibited higher general cognitive abilities (WISC-IV) and declarative learning efficiency (i.e., number of recalled words before and after sleep). Slow sleep spindles (11-13 Hz) in children age 8-11 y are associated with inter-individual differences in general cognitive abilities and learning efficiency. © 2014 Associated Professional Sleep Societies, LLC.

  17. A New Approach to Spindle Radial Error Evaluation Using a Machine Vision System

    Directory of Open Access Journals (Sweden)

    Kavitha C.

    2017-03-01

    Full Text Available The spindle rotational accuracy is one of the important issues in a machine tool which affects the surface topography and dimensional accuracy of a workpiece. This paper presents a machine-vision-based approach to radial error measurement of a lathe spindle using a CMOS camera and a PC-based image processing system. In the present work, a precisely machined cylindrical master is mounted on the spindle as a datum surface and variations of its position are captured using the camera for evaluating runout of the spindle. The Circular Hough Transform (CHT is used to detect variations of the centre position of the master cylinder during spindle rotation at subpixel level from a sequence of images. Radial error values of the spindle are evaluated using the Fourier series analysis of the centre position of the master cylinder calculated with the least squares curve fitting technique. The experiments have been carried out on a lathe at different operating speeds and the spindle radial error estimation results are presented. The proposed method provides a simpler approach to on-machine estimation of the spindle radial error in machine tools.

  18. Spindle-shaped Microstructures: Potential Models for Planktonic Life Forms on Other Worlds

    Science.gov (United States)

    Oehler, Dorothy Z.; Walsh, Maud M.; Sugitani, Kenichiro; House, Christopher H.

    2014-01-01

    Spindle-shaped, organic microstructures ("spindles") are now known from Archean cherts in three localities (Figs. 1-4): The 3 Ga Farrel Quartzite from the Pilbara of Australia [1]; the older, 3.3-3.4 Ga Strelley Pool Formation, also from the Pilbara of Australia [2]; and the 3.4 Ga Kromberg Formation of the Barberton Mountain Land of South Africa [3]. Though the spindles were previously speculated to be pseudofossils or epigenetic organic contaminants, a growing body of data suggests that these structures are bona fide microfossils and further, that they are syngenetic with the Archean cherts in which they occur [1-2, 4-10]. As such, the spindles are among some of the oldest-known organically preserved microfossils on Earth. Moreover, recent delta C-13 study of individual spindles from the Farrel Quartzite (using Secondary Ion Mass Spectrometry [SIMS]) suggests that the spindles may have been planktonic (living in open water), as opposed to benthic (living as bottom dwellers in contact with muds or sediments) [9]. Since most Precambrian microbiotas have been described from benthic, matforming communities, a planktonic lifestyle for the spindles suggests that these structures could represent a segment of the Archean biosphere that is poorly known. Here we synthesize the recent work on the spindles, and we add new observations regarding their geographic distribution, robustness, planktonic habit, and long-lived success. We then discuss their potential evolutionary and astrobiological significance.

  19. Electronic monitoring in bipolar disorder.

    Science.gov (United States)

    Faurholt-Jepsen, Maria

    2018-03-01

    Major reasons for the insufficient effects of current treatment options in bipolar disorder include delayed intervention for prodromal depressive and manic symptoms and decreased adherence to psychopharmacological treatment. The reliance on subjective information and clinical evaluations when diagnosing and assessing the severity of depressive and manic symptoms calls for less biased and more objective markers. By using electronic devices, fine-grained data on complex psychopathological aspects of bipolar disorder can be evaluated unobtrusively over the long term. Moreover, electronic data could possibly represent candidate markers of diagnosis and illness activity in bipolar disorder and allow for early and individualized intervention for prodromal symptoms outside clinical settings. 
The present dissertation concerns the use of electronic monitoring as a marker and treatment intervention in bipolar disorder and investigated the scientific literature and body of evidence within the area, which includes ten original study reports and two systematic reviews, one of which included a meta-analysis, conducted by the author of the dissertation. 
Taken together, the literature presented in this dissertation illustrates that 1) smartphone-based electronic self-monitoring of mood seems to reflect clinically assessed depressive and manic symptoms and enables the long-term characterization of mood

instability in bipolar disorder; 2) preliminary results suggest that smartphone-based automatically generated data (e.g. the number of text messages sent/day; the number of incoming and outgoing calls/day; the number of changes in cell tower IDs/day; and voice features) seem to reflect clinically assessed depressive and manic symptoms in bipolar disorder; 3) smartphone-based electronic self-monitoring had no effects on the severity of depressive and manic symptoms in bipolar disorder, according to a randomized controlled trial; and 4) electronic monitoring of psychomotor

  20. Epidemiologia do transtorno bipolar Epidemiology of bipolar disorders

    Directory of Open Access Journals (Sweden)

    Maurício Silva de Lima

    2005-01-01

    Full Text Available A formulação de políticas em saúde mental depende essencialmente de informações a respeito da freqüência e distribuição dos transtornos mentais. Nas últimas duas décadas, pesquisas de base populacional em epidemiologia psiquiátrica têm sido conduzidas, gerando informações detalhadas sobre freqüência, fatores de risco, incapacidade social e utilização de serviços de saúde. Neste artigo, dados sobre a epidemiologia do transtorno bipolar (TB são discutidos, a partir de resultados de recentes pesquisas populacionais: o estudo da Área de Captação Epidemiológica do Instituto Nacional de Saúde Mental dos Estados Unidos (ECA-NIMH, a Pesquisa Nacional de Comorbidade (NCS, a Pesquisa de Morbidade Psiquiátrica na Grã-Bretanha (OPCS, o Estudo Brasileiro Multicêntrico de Morbidade Psiquiátrica e os estudos longitudinais conduzidos por Angst, em Zurique. As estimativas de prevalências de transtorno bipolar são relativamente baixas, independentemente do lugar onde a pesquisa foi conduzida, do tipo de instrumento diagnóstico usado e dos períodos de tempo para os quais a prevalência se aplica. A partir da introdução do conceito de espectro bipolar, ampliando as fronteiras diagnósticas do TB, as estimativas de prevalências encontradas são substancialmente mais altas. Tais estimativas, entretanto, ainda carecem de validação em estudos populacionais. O transtorno afetivo bipolar é igualmente prevalente entre homens e mulheres, sendo mais freqüente entre solteiros ou separados. Indivíduos acometidos têm maiores taxas de desemprego e estão mais sujeitos a utilizarem serviços médicos e serem hospitalizados. O custo e a eficácia dos tratamentos do TB devem ser balanceados com o alto custo individual e social associados à enfermidade.Information about the epidemiology of bipolar disorders is essential for providing a framework for the formulation of effective mental health policy. In the last two decades, population

  1. Mounting arrangement for the drive system of an air-bearing spindle on a machine tool

    Science.gov (United States)

    Lunsford, J.S.; Crisp, D.W.; Petrowski, P.L.

    1987-12-07

    The present invention is directed to a mounting arrangement for the drive system of an air-bearing spindle utilized on a machine tool such as a lathe. The mounting arrangement of the present invention comprises a housing which is secured to the casing of the air bearing in such a manner that the housing position can be selectively adjusted to provide alignment of the air-bearing drive shaft supported by the housing and the air-bearing spindle. Once this alignment is achieved the air between spindle and the drive arrangement is maintained in permanent alignment so as to overcome misalignment problems encountered in the operation of the machine tool between the air-bearing spindle and the shaft utilized for driving the air-bearing spindle.

  2. A case of spindle cell (squamous) carcinoma (WHO) of the lung

    Energy Technology Data Exchange (ETDEWEB)

    Nakano, Hidehiko; Minato, Kouichi; Hojyo, Shinobu (Gunma Univ., Maebashi (Japan). School of Medicine) (and others)

    1991-12-01

    A 76-year-old man with spindle cell (squamous) carcinoma of the lung developed fatal respiratory failure after limited thoracic irradiation at a total dose of 18 Gy. He developed severe pulmonary toxicity, which presented as dry cough, dyspnea, and pulmonary infiltrates extending beyond the radiation field. Microscopically, a transitional form of squamous to spindle-shaped cells was observed in the primary tumor, located at right S8. Immunohistochemical examination showed positive staining of spindle cells for keratin, vimentin, and EMA, but not for desmin. These results indicate that the spindle cells had characteristics of squamous epithelial cells, and differed from carcinosarcoma. Distant metastatic lesions were composed of only the spindle cell component. (author).

  3. A 62-kD protein required for mitotic progression is associated with the mitotic apparatus during M-phase and with the nucleus during interphase

    OpenAIRE

    Johnston, Jennifer A.; Sloboda, Roger D.

    1992-01-01

    A protein of 62 kD is a substrate of a calcium/calmodulin-dependent protein kinase, and both proteins copurify with isolated mitotic apparatuses (Dinsmore, J. H., and R. D. Sloboda. 1988. Cell. 53:769- 780). Phosphorylation of the 62-kD protein increases after fertilization; maximum incorporation of phosphate occurs during late metaphase and anaphase and correlates directly with microtubule disassembly as determined by in vitro experiments with isolated mitotic apparatuses. Because 62-kD prot...

  4. Thalamic Spindles Promote Memory Formation during Sleep through Triple Phase-Locking of Cortical, Thalamic, and Hippocampal Rhythms.

    Science.gov (United States)

    Latchoumane, Charles-Francois V; Ngo, Hong-Viet V; Born, Jan; Shin, Hee-Sup

    2017-07-19

    While the interaction of the cardinal rhythms of non-rapid-eye-movement (NREM) sleep-the thalamo-cortical spindles, hippocampal ripples, and the cortical slow oscillations-is thought to be critical for memory consolidation during sleep, the role spindles play in this interaction is elusive. Combining optogenetics with a closed-loop stimulation approach in mice, we show here that only thalamic spindles induced in-phase with cortical slow oscillation up-states, but not out-of-phase-induced spindles, improve consolidation of hippocampus-dependent memory during sleep. Whereas optogenetically stimulated spindles were as efficient as spontaneous spindles in nesting hippocampal ripples within their excitable troughs, stimulation in-phase with the slow oscillation up-state increased spindle co-occurrence and frontal spindle-ripple co-occurrence, eventually resulting in increased triple coupling of slow oscillation-spindle-ripple events. In-phase optogenetic suppression of thalamic spindles impaired hippocampus-dependent memory. Our results suggest a causal role for thalamic sleep spindles in hippocampus-dependent memory consolidation, conveyed through triple coupling of slow oscillations, spindles, and ripples. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. Mixed features in bipolar disorder.

    Science.gov (United States)

    Solé, Eva; Garriga, Marina; Valentí, Marc; Vieta, Eduard

    2017-04-01

    Mixed affective states, defined as the coexistence of depressive and manic symptoms, are complex presentations of manic-depressive illness that represent a challenge for clinicians at the levels of diagnosis, classification, and pharmacological treatment. The evidence shows that patients with bipolar disorder who have manic/hypomanic or depressive episodes with mixed features tend to have a more severe form of bipolar disorder along with a worse course of illness and higher rates of comorbid conditions than those with non-mixed presentations. In the updated Diagnostic and Statistical Manual of Mental Disorders (5th ed.; DSM-5), the definition of "mixed episode" has been removed, and subthreshold nonoverlapping symptoms of the opposite pole are captured using a "with mixed features" specifier applied to manic, hypomanic, and major depressive episodes. However, the list of symptoms proposed in the DSM-5 specifier has been widely criticized, because it includes typical manic symptoms (such as elevated mood and grandiosity) that are rare among patients with mixed depression, while excluding symptoms (such as irritability, psychomotor agitation, and distractibility) that are frequently reported in these patients. With the new classification, mixed depressive episodes are three times more common in bipolar II compared with unipolar depression, which partly contributes to the increased risk of suicide observed in bipolar depression compared to unipolar depression. Therefore, a specific diagnostic category would imply an increased diagnostic sensitivity, would help to foster early identification of symptoms and ensure specific treatment, as well as play a role in suicide prevention in this population.

  6. Mitotically Active Leiomyoma of the Uterus in a Postmenopausal Breast Cancer Patient Receiving Tamoxifen

    Directory of Open Access Journals (Sweden)

    I-Feng Liu

    2006-06-01

    Conclusion: Endometrial cancer is rarely noted in breast cancer patients taking tamoxifen. Further, none have reported mitotically active leiomyoma of the uterus. From this case, endometrial proliferation and mitotically active leiomyoma of the uterus may be related to tamoxifen therapy, and should not be neglected in breast cancer patients.

  7. A role for mitotic bookmarking of SOX2 in pluripotency and differentiation.

    Science.gov (United States)

    Deluz, Cédric; Friman, Elias T; Strebinger, Daniel; Benke, Alexander; Raccaud, Mahé; Callegari, Andrea; Leleu, Marion; Manley, Suliana; Suter, David M

    2016-11-15

    Mitotic bookmarking transcription factors remain bound to chromosomes during mitosis and were proposed to regulate phenotypic maintenance of stem and progenitor cells at the mitosis-to-G1 (M-G1) transition. However, mitotic bookmarking remains largely unexplored in most stem cell types, and its functional relevance for cell fate decisions remains unclear. Here we screened for mitotic chromosome binding within the pluripotency network of embryonic stem (ES) cells and show that SOX2 and OCT4 remain bound to mitotic chromatin through their respective DNA-binding domains. Dynamic characterization using photobleaching-based methods and single-molecule imaging revealed quantitatively similar specific DNA interactions, but different nonspecific DNA interactions, of SOX2 and OCT4 with mitotic chromatin. Using ChIP-seq (chromatin immunoprecipitation [ChIP] combined with high-throughput sequencing) to assess the genome-wide distribution of SOX2 on mitotic chromatin, we demonstrate the bookmarking activity of SOX2 on a small set of genes. Finally, we investigated the function of SOX2 mitotic bookmarking in cell fate decisions and show that its absence at the M-G1 transition impairs pluripotency maintenance and abrogates its ability to induce neuroectodermal differentiation but does not affect reprogramming efficiency toward induced pluripotent stem cells. Our study demonstrates the mitotic bookmarking property of SOX2 and reveals its functional importance in pluripotency maintenance and ES cell differentiation. © 2016 Deluz et al.; Published by Cold Spring Harbor Laboratory Press.

  8. Integrated Neurobiology of Bipolar Disorder

    Science.gov (United States)

    Maletic, Vladimir; Raison, Charles

    2014-01-01

    From a neurobiological perspective there is no such thing as bipolar disorder. Rather, it is almost certainly the case that many somewhat similar, but subtly different, pathological conditions produce a disease state that we currently diagnose as bipolarity. This heterogeneity – reflected in the lack of synergy between our current diagnostic schema and our rapidly advancing scientific understanding of the condition – limits attempts to articulate an integrated perspective on bipolar disorder. However, despite these challenges, scientific findings in recent years are beginning to offer a provisional “unified field theory” of the disease. This theory sees bipolar disorder as a suite of related neurodevelopmental conditions with interconnected functional abnormalities that often appear early in life and worsen over time. In addition to accelerated loss of volume in brain areas known to be essential for mood regulation and cognitive function, consistent findings have emerged at a cellular level, providing evidence that bipolar disorder is reliably associated with dysregulation of glial–neuronal interactions. Among these glial elements are microglia – the brain’s primary immune elements, which appear to be overactive in the context of bipolarity. Multiple studies now indicate that inflammation is also increased in the periphery of the body in both the depressive and manic phases of the illness, with at least some return to normality in the euthymic state. These findings are consistent with changes in the hypothalamic–pituitary–adrenal axis, which are known to drive inflammatory activation. In summary, the very fact that no single gene, pathway, or brain abnormality is likely to ever account for the condition is itself an extremely important first step in better articulating an integrated perspective on both its ontological status and pathogenesis. Whether this perspective will translate into the discovery of innumerable more homogeneous forms of

  9. Human SGT interacts with Bag-6/Bat-3/Scythe and cells with reduced levels of either protein display persistence of few misaligned chromosomes and mitotic arrest

    International Nuclear Information System (INIS)

    Winnefeld, Marc; Grewenig, Annabel; Schnoelzer, Martina; Spring, Herbert; Knoch, Tobias A.; Gan, Eugene C.; Rommelaere, Jean; Cziepluch, Celina

    2006-01-01

    The human small glutamine-rich TPR-containing protein (hSGT) is essential for cell division since RNA-interference-mediated strong reduction of hSGT protein levels causes mitotic arrest (M. Winnefeld, J. Rommelaere, and C. Cziepluch, The human small glutamine-rich TPR-containing protein is required for progress through cell division, Exp. Cell Res. 293 (2004), 43-57). Analysis of HeLa cells expressing a histone 2A-YFP fusion protein revealed the continuous presence of few mislocalized chromosomes close to the spindle poles as possible cause for hSGT depletion-dependent prometaphase arrest. Cells unable to rescue these mislocalized chromosomes into the metaphase plate died at this stage through apoptosis. In order to address hSGT function at the molecular level, mass spectrometry analysis of proteins which co-immunoprecipitated with Flag-tagged hSGT was performed. Thereby, Hsp70 and Bag-6/Bat-3/Scythe were identified as novel hSGT interaction partners while interaction with Hsc70 was confirmed. Results obtained with truncated versions of the hSGT protein revealed that Bag-6/Bat-3/Scythe and Hsp70 or Hsc70 were independently able to form complexes with hSGT. Interaction of hSGT with Hsc70, Hsp70 or Bag-6/Bat-3/Scythe was demonstrated in prometaphase, thereby suggesting a possible role for complexes containing hSGT and distinct (co)-chaperones during mitosis. Finally, cells from populations with reduced levels of Bag-6/Bat-3/Scythe also displayed persistence of mislocalized chromosomes and mitotic arrest, which strongly indicated that hSGT-Bag-6/Bat-3/Scythe complexes could be directly or indirectly required for complete chromosome congression

  10. The small molecule inhibitor YK-4-279 disrupts mitotic progression of neuroblastoma cells, overcomes drug resistance and synergizes with inhibitors of mitosis.

    Science.gov (United States)

    Kollareddy, Madhu; Sherrard, Alice; Park, Ji Hyun; Szemes, Marianna; Gallacher, Kelli; Melegh, Zsombor; Oltean, Sebastian; Michaelis, Martin; Cinatl, Jindrich; Kaidi, Abderrahmane; Malik, Karim

    2017-09-10

    Neuroblastoma is a biologically and clinically heterogeneous pediatric malignancy that includes a high-risk subset for which new therapeutic agents are urgently required. As well as MYCN amplification, activating point mutations of ALK and NRAS are associated with high-risk and relapsing neuroblastoma. As both ALK and RAS signal through the MEK/ERK pathway, we sought to evaluate two previously reported inhibitors of ETS-related transcription factors, which are transcriptional mediators of the Ras-MEK/ERK pathway in other cancers. Here we show that YK-4-279 suppressed growth and triggered apoptosis in nine neuroblastoma cell lines, while BRD32048, another ETV1 inhibitor, was ineffective. These results suggest that YK-4-279 acts independently of ETS-related transcription factors. Further analysis reveals that YK-4-279 induces mitotic arrest in prometaphase, resulting in subsequent cell death. Mechanistically, we show that YK-4-279 inhibits the formation of kinetochore microtubules, with treated cells showing a broad range of abnormalities including multipolar, fragmented and unseparated spindles, together leading to disrupted progression through mitosis. Notably, YK-4-279 does not affect microtubule acetylation, unlike the conventional mitotic poisons paclitaxel and vincristine. Consistent with this, we demonstrate that YK-4-279 overcomes vincristine-induced resistance in two neuroblastoma cell-line models. Furthermore, combinations of YK-4-279 with vincristine, paclitaxel or the Aurora kinase A inhibitor MLN8237/Alisertib show strong synergy, particularly at low doses. Thus, YK-4-279 could potentially be used as a single-agent or in combination therapies for the treatment of high-risk and relapsing neuroblastoma, as well as other cancers. Copyright © 2017 The Author(s). Published by Elsevier B.V. All rights reserved.

  11. Disturbed mitotic progression and genome segregation are involved in cell transformation mediated by nano-TiO2 long-term exposure.

    Science.gov (United States)

    Huang, Shing; Chueh, Pin Ju; Lin, Yun-Wei; Shih, Tung-Sheng; Chuang, Show-Mei

    2009-12-01

    Titanium dioxide (TiO2) nano-particles (cosmetics and pharmaceuticals because of their low toxicity. However, recent studies have shown that TiO2 nano-particles (nano-TiO2) induce cytotoxicity and genotoxicity in various lines of cultured cells as well as tumorigenesis in animal models. The biological roles of nano-TiO2 are shown to be controversial and no comprehensive study paradigm has been developed to investigate their molecular mechanisms. In this study, we showed that short-term exposure to nano-TiO2 enhanced cell proliferation, survival, ERK signaling activation and ROS production in cultured fibroblast cells. Moreover, long-term exposure to nano-TiO2 not only increased cell survival and growth on soft agar but also the numbers of multinucleated cells and micronucleus (MN) as suggested in confocal microscopy analysis. Cell cycle phase analysis showed G2/M delay and slower cell division in long-term exposed cells. Most importantly, long-term TiO2 exposure remarkably affected mitotic progression at anaphase and telophase leading to aberrant multipolar spindles and chromatin alignment/segregation. Moreover, PLK1 was demonstrated as the target for nano-TiO2 in the regulation of mitotic progression and exit. Notably, a higher fraction of sub-G1 phase population appeared in TiO2-exposed cells after releasing from G2/M synchronization. Our results demonstrate that long-term exposure to nano-TiO2 disturbs cell cycle progression and duplicated genome segregation, leading to chromosomal instability and cell transformation.

  12. Gene-specific factors determine mitotic expression and bookmarking via alternate regulatory elements.

    Science.gov (United States)

    Arampatzi, Panagiota; Gialitakis, Manolis; Makatounakis, Takis; Papamatheakis, Joseph

    2013-02-01

    Transcriptional silencing during mitosis is caused by inactivation of critical transcriptional regulators and/or chromatin condensation. Inheritance of gene expression patterns through cell division involves various bookmarking mechanisms. In this report, we have examined the mitotic and post-mitotic expression of the DRA major histocompatibility class II (MHCII) gene in different cell types. During mitosis the constitutively MHCII-expressing B lymphoblastoid cells showed sustained occupancy of the proximal promoter by the cognate enhanceosome and general transcription factors. In contrast, although mitotic epithelial cells were depleted of these proteins irrespectively of their MHCII transcriptional activity, a distal enhancer selectively recruited the PP2A phosphatase via NFY and maintained chromatin accessibility. Based on our data, we propose a novel chromatin anti-condensation role for this element in mitotic bookmarking and timing of post-mitotic transcriptional reactivation.

  13. Study of Contactless Power Supply for Spindle Ultrasonic Vibrator

    Science.gov (United States)

    Chen, T. R.; Lee, Y. L.; Liu, H. T.; Chen, S. M.; Chang, H. Z.

    2017-11-01

    In this study, a contactless power supply for the ultrasonic motor on the spindle is proposed. The proposed power supply is composed of a series-parallel resonant circuit and a cylindrical contactless transformer. Based on the study and rotation experiments, it can be seen that the proposed power supply can both provide a stable ac power with 25 kHz / 70 V to the ultrasonic motor. When the output power is 250 W, the efficiency of the proposed supply is 89.8 % in respectively rotation tests. When the output power is more than 150 W, the efficiency of the proposed supply is higher than 80 % within the rated output power range.

  14. Proprioceptive Feedback through a Neuromorphic Muscle Spindle Model

    Directory of Open Access Journals (Sweden)

    Lorenzo Vannucci

    2017-06-01

    Full Text Available Connecting biologically inspired neural simulations to physical or simulated embodiments can be useful both in robotics, for the development of a new kind of bio-inspired controllers, and in neuroscience, to test detailed brain models in complete action-perception loops. The aim of this work is to develop a fully spike-based, biologically inspired mechanism for the translation of proprioceptive feedback. The translation is achieved by implementing a computational model of neural activity of type Ia and type II afferent fibers of muscle spindles, the primary source of proprioceptive information, which, in mammals is regulated through fusimotor activation and provides necessary adjustments during voluntary muscle contractions. As such, both static and dynamic γ-motoneurons activities are taken into account in the proposed model. Information from the actual proprioceptive sensors (i.e., motor encoders is then used to simulate the spindle contraction and relaxation, and therefore drive the neural activity. To assess the feasibility of this approach, the model is implemented on the NEST spiking neural network simulator and on the SpiNNaker neuromorphic hardware platform and tested on simulated and physical robotic platforms. The results demonstrate that the model can be used in both simulated and real-time robotic applications to translate encoder values into a biologically plausible neural activity. Thus, this model provides a completely spike-based building block, suitable for neuromorphic platforms, that will enable the development of sensory-motor closed loops which could include neural simulations of areas of the central nervous system or of low-level reflexes.

  15. The Multidimensional Aspects of Sleep Spindles and Their Relationship to Word-Pair Memory Consolidation.

    Science.gov (United States)

    Lustenberger, Caroline; Wehrle, Flavia; Tüshaus, Laura; Achermann, Peter; Huber, Reto

    2015-07-01

    Several studies proposed a link between sleep spindles and sleep dependent memory consolidation in declarative learning tasks. In addition to these state-like aspects of sleep spindles, they have also trait-like characteristics, i.e., were related to general cognitive performance, an important distinction that has often been neglected in correlative studies. Furthermore, from the multitude of different sleep spindle measures, often just one specific aspect was analyzed. Thus, we aimed at taking multidimensional aspects of sleep spindles into account when exploring their relationship to word-pair memory consolidation. Each subject underwent 2 study nights with all-night high-density electroencephalographic (EEG) recordings. Sleep spindles were automatically detected in all EEG channels. Subjects were trained and tested on a word-pair learning task in the evening, and retested in the morning to assess sleep related memory consolidation (overnight retention). Trait-like aspects refer to the mean of both nights and state-like aspects were calculated as the difference between night 1 and night 2. Sleep laboratory. Twenty healthy male subjects (age: 23.3 ± 2.1 y). Overnight retention was negatively correlated with trait-like aspects of fast sleep spindle density and positively with slow spindle density on a global level. In contrast, state-like aspects were observed for integrated slow spindle activity, which was positively related to the differences in overnight retention in specific regions. Our results demonstrate the importance of a multidimensional approach when investigating the relationship between sleep spindles and memory consolidation and thereby provide a more complete picture explaining divergent findings in the literature. © 2015 Associated Professional Sleep Societies, LLC.

  16. Disjunction of conjoined twins: Cdk1, Cdh1 and separation of centrosomes

    Directory of Open Access Journals (Sweden)

    Surana Uttam

    2006-06-01

    Full Text Available Abstract Accurate transmission of chromosomes from parent to progeny cell requires assembly of a bipolar spindle. Centrosomes (spindle pole body in yeast are critical for the biogenesis of this complex mitotic apparatus since they confer bipolarity on the spindle and serve as the site of microtubule polymerization. In each division cycle, the centrosome is duplicated and the sister-centrosomes move away from each other, forming the two poles of the spindle. While the structure and the duplication of centrosomes have been investigated extensively, the understanding of the control of their segregation remains scant. Recent findings are beginning to yield insights into the regulation of centrosome segregation in yeast and its link to the mitotic kinase.

  17. Bipolar polygenic loading and bipolar spectrum features in major depressive disorder

    NARCIS (Netherlands)

    Wiste, Anna; Robinson, Elise B.; Milaneschi, Yuri; Meier, Sandra; Ripke, Stephan; Clements, Caitlin C.; Fitzmaurice, Garrett M.; Rietschel, Marcella; Penninx, Brenda W.; Smoller, Jordan W.; Perlis, Roy H.

    Objectives Family and genetic studies indicate overlapping liability for major depressive disorder and bipolar disorder. The purpose of the present study was to determine whether this shared genetic liability influences clinical presentation. Methods A polygenic risk score for bipolar disorder,

  18. Design of Accelerated Reliability Test for CNC Motorized Spindle Based on Vibration Signal

    Directory of Open Access Journals (Sweden)

    Chen Chao

    2016-01-01

    Full Text Available Motorized spindle is the key functional component of CNC machining centers which is a mechatronics system with long life and high reliability. The reliability test cycle of motorized spindle is too long and infeasible. This paper proposes a new accelerated test for reliability evaluation of motorized spindle. By field reliability test, authors collect and calculate the load data including rotational speed, cutting force and torque. Load spectrum distribution law is analyzed. And authors design a test platform to apply the load spectrum. A new method to define the fuzzy acceleration factor based on the vibration signal is proposed. Then the whole test plan of accelerated reliability test is done.

  19. Analysis of radial runout for symmetric and asymmetric HDD spindle motors with rotor eccentricity

    International Nuclear Information System (INIS)

    Kim, T.-J.; Kim, K.-T.; Hwang, S.-M.; Lee, S.-B.; Park, N.-G.

    2001-01-01

    Radial runout of disk drive spindle is one of the major limiting factors in achieving higher track densities in hard disk drives. Mechanical, magnetic and their coupled origins, such as unbalanced mass, reaction forces and magnetic forces, introduce radial runout of spindle motors. In this paper, radial magnetic forces are calculated with respect to the various rotor eccentricities using analytic method. Based on the results of the radial magnetic forces, the radial runout of the spindle motor is analyzed using finite element and transfer matrices. Results show that an asymmetric motor has a worse performance on unbalanced magnetic forces and radial runout when mechanical and magnetic coupling exists

  20. Sleep-spindle detection: crowdsourcing and evaluating performance of experts, non-experts and automated methods

    DEFF Research Database (Denmark)

    Warby, Simon C.; Wendt, Sabrina Lyngbye; Welinder, Peter

    2014-01-01

    to crowdsource spindle identification by human experts and non-experts, and we compared their performance with that of automated detection algorithms in data from middle- to older-aged subjects from the general population. We also refined methods for forming group consensus and evaluating the performance...... that crowdsourcing the scoring of sleep data is an efficient method to collect large data sets, even for difficult tasks such as spindle identification. Further refinements to spindle detection algorithms are needed for middle- to older-aged subjects....

  1. Genetic analysis of the spindle checkpoint genes san-1, mdf-2, bub-3 and the CENP-F homologues hcp-1 and hcp-2 in Caenorhabditis elegans

    Directory of Open Access Journals (Sweden)

    Moore Landon L

    2008-02-01

    Full Text Available Abstract Background The spindle checkpoint delays the onset of anaphase until all sister chromatids are aligned properly at the metaphase plate. To investigate the role san-1, the MAD3 homologue, has in Caenorhabditis elegans embryos we used RNA interference (RNAi to identify genes synthetic lethal with the viable san-1(ok1580 deletion mutant. Results The san-1(ok1580 animal has low penetrating phenotypes including an increased incidence of males, larvae arrest, slow growth, protruding vulva, and defects in vulva morphogenesis. We found that the viability of san-1(ok1580 embryos is significantly reduced when HCP-1 (CENP-F homologue, MDF-1 (MAD-1 homologue, MDF-2 (MAD-2 homologue or BUB-3 (predicted BUB-3 homologue are reduced by RNAi. Interestingly, the viability of san-1(ok1580 embryos is not significantly reduced when the paralog of HCP-1, HCP-2, is reduced. The phenotype of san-1(ok1580;hcp-1(RNAi embryos includes embryonic and larval lethality, abnormal organ development, and an increase in abnormal chromosome segregation (aberrant mitotic nuclei, anaphase bridging. Several of the san-1(ok1580;hcp-1(RNAi animals displayed abnormal kinetochore (detected by MPM-2 and microtubule structure. The survival of mdf-2(RNAi;hcp-1(RNAi embryos but not bub-3(RNAi;hcp-1(RNAi embryos was also compromised. Finally, we found that san-1(ok1580 and bub-3(RNAi, but not hcp-1(RNAi embryos, were sensitive to anoxia, suggesting that like SAN-1, BUB-3 has a functional role as a spindle checkpoint protein. Conclusion Together, these data suggest that in the C. elegans embryo, HCP-1 interacts with a subset of the spindle checkpoint pathway. Furthermore, the fact that san-1(ok1580;hcp-1(RNAi animals had a severe viability defect whereas in the san-1(ok1580;hcp-2(RNAi and san-1(ok1580;hcp-2(ok1757 animals the viability defect was not as severe suggesting that hcp-1 and hcp-2 are not completely redundant.

  2. Epigenetic characteristics of the mitotic chromosome in 1D and 3D.

    Science.gov (United States)

    Oomen, Marlies E; Dekker, Job

    2017-04-01

    While chromatin characteristics in interphase are widely studied, characteristics of mitotic chromatin and their inheritance through mitosis are still poorly understood. During mitosis, chromatin undergoes dramatic changes: transcription stalls, chromatin-binding factors leave the chromatin, histone modifications change and chromatin becomes highly condensed. Many key insights into mitotic chromosome state and conformation have come from extensive microscopy studies over the last century. Over the last decade, the development of 3C-based techniques has enabled the study of higher order chromosome organization during mitosis in a genome-wide manner. During mitosis, chromosomes lose their cell type-specific and locus-dependent chromatin organization that characterizes interphase chromatin and fold into randomly positioned loop arrays. Upon exit of mitosis, cells are capable of quickly rearranging the chromosome conformation to form the cell type-specific interphase organization again. The information that enables this rearrangement after mitotic exit is thought to be encoded at least in part in mitotic bookmarks, e.g. histone modifications and variants, histone remodelers, chromatin factors, and non-coding RNA. Here we give an overview of the chromosomal organization and epigenetic characteristics of interphase and mitotic chromatin in vertebrates. Second, we describe different ways in which mitotic bookmarking enables epigenetic memory of the features of interphase chromatin through mitosis. And third, we explore the role of epigenetic modifications and mitotic bookmarking in cell differentiation.

  3. Unsplit bipolar pulse forming line

    Science.gov (United States)

    Rhodes, Mark A [Pleasanton, CA

    2011-05-24

    A bipolar pulse forming transmission line module and system for linear induction accelerators having first, second, third, and fourth planar conductors which form a sequentially arranged interleaved stack having opposing first and second ends, with dielectric layers between the conductors. The first and second planar conductors are connected to each other at the first end, and the first and fourth planar conductors are connected to each other at the second end via a shorting plate. The third planar conductor is electrically connectable to a high voltage source, and an internal switch functions to short at the first end a high voltage from the third planar conductor to the fourth planar conductor to produce a bipolar pulse at the acceleration axis with a zero net time integral. Improved access to the switch is enabled by an aperture through the shorting plate and the proximity of the aperture to the switch.

  4. Course of Subthreshold Bipolar Disorder in Youth: Diagnostic Progression from Bipolar Disorder Not Otherwise Specified

    Science.gov (United States)

    Axelson, David A.; Birmaher, Boris; Strober, Michael A.; Goldstein, Benjamin I.; Ha, Wonho; Gill, Mary Kay; Goldstein, Tina R.; Yen, Shirley; Hower, Heather; Hunt, Jeffrey I.; Liao, Fangzi; Iyengar, Satish; Dickstein, Daniel; Kim, Eunice; Ryan, Neal D.; Frankel, Erica; Keller, Martin B.

    2011-01-01

    Objective: To determine the rate of diagnostic conversion from an operationalized diagnosis of bipolar disorder not otherwise specified (BP-NOS) to bipolar I disorder (BP-I) or bipolar II disorder (BP-II) in youth over prospective follow-up and to identify factors associated with conversion. Method: Subjects were 140 children and adolescents…

  5. Bipolar (spectrum) disorder and mood stabilization: standing at the crossroads?

    OpenAIRE

    De Fruyt, Jurgen; Demyttenaere, Koen

    2007-01-01

    Diagnosis and treatment of bipolar disorder has long been a neglected discipline. Recent years have shown an upsurge in bipolar research. When compared to major depressive disorder, bipolar research still remains limited and more expert based than evidence based. In bipolar diagnosis the focus is shifting from classic mania to bipolar depression and hypomania. There is a search for bipolar signatures in symptoms and course of major depressive episodes. The criteria for hypomania are softened,...

  6. [Bipolar disorders in DSM-5].

    Science.gov (United States)

    Severus, E; Bauer, M

    2014-05-01

    In spring 2013 the fifth edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-5) edited by the American Psychiatric Association was published. The DSM-5 has also brought some important changes regarding bipolar disorders. The goal of this manuscript is to review the novelties in DSM-5 and to evaluate the implications of these changes. The diagnostic criteria as well as the additional remarks provided in the running text of DSM-5 were carefully appraised. For the first time diagnostic criteria are provided for disorders which up to now have been considered as subthreshold bipolar disorders. Furthermore, mixed episodes were eliminated and instead a mixed specifier was introduced. An increase in goal-directed activity/energy is now one of the obligatory symptoms for a (hypo)manic episode. Diagnostic guidance is provided as to when a (hypo)manic episode that has developed during treatment with an antidepressant has to be judged to be causally related to antidepressants and when this episode has only occurred coincidentally with antidepressant use. While some of the novelties are clearly useful, e.g. addition of increased goal-directed activity/energy as obligatory symptom for (hypo)manic episodes, this remains to be demonstrated for others, such as the definition of various subthreshold bipolar disorders.

  7. Bipolar Disorder and Obsessive Compulsive Disorder Comorbidity

    Directory of Open Access Journals (Sweden)

    Necla Keskin

    2014-08-01

    Full Text Available The comorbidity of bipolar disorder and anxiety disorders is a well known concept. Obsessive-compulsive disorder is the most commonly seen comorbid anxiety disorder in bipolar patients. Some genetic variants, neurotransmitters especially serotonergic systems and second-messenger systems are thought to be responsible for its etiology. Bipolar disorder alters the clinical aspects of obsessive compulsive disorder and is associated with poorer outcome. The determination of comorbidity between bipolar disorder and obsessive compulsive disorder is quite important for appropriate clinical management and treatment. [Psikiyatride Guncel Yaklasimlar - Current Approaches in Psychiatry 2014; 6(4.000: 429-437

  8. Structure–Biological Function Relationship Extended to Mitotic Arrest-Deficient 2-Like Protein Mad2 Native and Mutants-New Opportunity for Genetic Disorder Control

    Directory of Open Access Journals (Sweden)

    Speranta Avram

    2014-11-01

    Full Text Available Overexpression of mitotic arrest-deficient proteins Mad1 and Mad2, two components of spindle assembly checkpoint, is a risk factor for chromosomal instability (CIN and a trigger of many genetic disorders. Mad2 transition from inactive open (O-Mad2 to active closed (C-Mad2 conformations or Mad2 binding to specific partners (cell-division cycle protein 20 (Cdc20 or Mad1 were targets of previous pharmacogenomics studies. Here, Mad2 binding to Cdc20 and the interconversion rate from open to closed Mad2 were predicted and the molecular features with a critical contribution to these processes were determined by extending the quantitative structure-activity relationship (QSAR method to large-size proteins such as Mad2. QSAR models were built based on available published data on 23 Mad2 mutants inducing CIN-related functional changes. The most relevant descriptors identified for predicting Mad2 native and mutants action mechanism and their involvement in genetic disorders are the steric (van der Waals area and solvent accessible area and their subdivided and energetic van der Waals energy descriptors. The reliability of our QSAR models is indicated by significant values of statistical coefficients: Cross-validated correlation q2 (0.53–0.65 and fitted correlation r2 (0.82–0.90. Moreover, based on established QSAR equations, we rationally design and analyze nine de novo Mad2 mutants as possible promoters of CIN.

  9. Manipulating sleep spindles--expanding views on sleep, memory, and disease.

    Science.gov (United States)

    Astori, Simone; Wimmer, Ralf D; Lüthi, Anita

    2013-12-01

    Sleep spindles are distinctive electroencephalographic (EEG) oscillations emerging during non-rapid-eye-movement sleep (NREMS) that have been implicated in multiple brain functions, including sleep quality, sensory gating, learning, and memory. Despite considerable knowledge about the mechanisms underlying these neuronal rhythms, their function remains poorly understood and current views are largely based on correlational evidence. Here, we review recent studies in humans and rodents that have begun to broaden our understanding of the role of spindles in the normal and disordered brain. We show that newly identified molecular substrates of spindle oscillations, in combination with evolving technological progress, offer novel targets and tools to selectively manipulate spindles and dissect their role in sleep-dependent processes. Copyright © 2013 Elsevier Ltd. All rights reserved.

  10. Prediction model and experimental validation for the thermal deformation of motorized spindle

    Science.gov (United States)

    Zhang, Lixiu; Li, Jinpeng; Wu, Yuhou; Zhang, Ke; Wang, Yawen

    2018-02-01

    The thermal deformation of motorized spindle has a great influence on the precision of numerical control (NC) machine tools. Thus, it is crucial to predict the thermal deformation in the design and operation control phase by numerical simulation and improve the precision of NC machine tools. In order to achieve this, an accurate thermal deformation prediction model for motorized spindle is required. In this paper, a model for predicting the thermal error of motorized spindle based on finite element method and parameter optimization is proposed. Levenberg-Marquardt (LM) method is applied to optimize the heat transfer coefficient of motorized spindle by using surface temperature data measured. The optimized heat transfer coefficient is then taken as one of the boundary condition of the finite element model. The boundary conditions about heat of the finite element model are obtained by energy loss experiment. The proposed model is validated by experimental results, and the results have shown well correlation.

  11. Afferent Innervation, Muscle Spindles, and Contractures Following Neonatal Brachial Plexus Injury in a Mouse Model.

    Science.gov (United States)

    Nikolaou, Sia; Hu, Liangjun; Cornwall, Roger

    2015-10-01

    We used an established mouse model of elbow flexion contracture after neonatal brachial plexus injury (NBPI) to test the hypothesis that preservation of afferent innervation protects against contractures and is associated with preservation of muscle spindles and ErbB signaling. A model of preganglionic C5 through C7 NBPI was first tested in mice with fluorescent axons using confocal imaging to confirm preserved afferent innervation of spindles despite motor end plate denervation. Preganglionic and postganglionic injuries were then created in wild-type mice. Four weeks later, we assessed total and afferent denervation of the elbow flexors by musculocutaneous nerve immunohistochemistry. Biceps muscle volume and cross-sectional area were measured by micro computed tomography. An observer who was blinded to the study protocol measured elbow flexion contractures. Biceps spindle and muscle fiber morphology and ErbB signaling pathway activity were assessed histologically and immunohistochemically. Preganglionic and postganglionic injuries caused similar total denervation and biceps muscle atrophy. However, after preganglionic injuries, afferent innervation was partially preserved and elbow flexion contractures were significantly less severe. Spindles degenerated after postganglionic injury but were preserved after preganglionic injury. ErbB signaling was inactivated in denervated spindles after postganglionic injury but ErbB signaling activity was preserved in spindles after preganglionic injury with retained afferent innervation. Preganglionic and postganglionic injuries were associated with upregulation of ErbB signaling in extrafusal muscle fibers. Contractures after NBPI are associated with muscle spindle degeneration and loss of spindle ErbB signaling activity. Preservation of afferent innervation maintained spindle development and ErbB signaling activity, and protected against contractures. Pharmacologic modulation of ErbB signaling, which is being investigated as a

  12. Bipolar mixed features - Results from the comparative effectiveness for bipolar disorder (Bipolar CHOICE) study.

    Science.gov (United States)

    Tohen, Mauricio; Gold, Alexandra K; Sylvia, Louisa G; Montana, Rebecca E; McElroy, Susan L; Thase, Michael E; Rabideau, Dustin J; Nierenberg, Andrew A; Reilly-Harrington, Noreen A; Friedman, Edward S; Shelton, Richard C; Bowden, Charles L; Singh, Vivek; Deckersbach, Thilo; Ketter, Terence A; Calabrese, Joseph R; Bobo, William V; McInnis, Melvin G

    2017-08-01

    DSM-5 changed the criteria from DSM-IV for mixed features in mood disorder episodes to include non-overlapping symptoms of depression and hypomania/mania. It is unknown if, by changing these criteria, the same group would qualify for mixed features. We assessed how those meeting DSM-5 criteria for mixed features compare to those meeting DSM-IV criteria. We analyzed data from 482 adult bipolar patients in Bipolar CHOICE, a randomized comparative effectiveness trial. Bipolar diagnoses were confirmed through the MINI International Neuropsychiatric Interview (MINI). Presence and severity of mood symptoms were collected with the Bipolar Inventory of Symptoms Scale (BISS) and linked to DSM-5 and DSM-IV mixed features criteria. Baseline demographics and clinical variables were compared between mood episode groups using ANOVA for continuous variables and chi-square tests for categorical variables. At baseline, the frequency of DSM-IV mixed episodes diagnoses obtained with the MINI was 17% and with the BISS was 20%. Using DSM-5 criteria, 9% of participants met criteria for hypomania/mania with mixed features and 12% met criteria for a depressive episode with mixed features. Symptom severity was also associated with increased mixed features with a high rate of mixed features in patients with mania/hypomania (63.8%) relative to those with depression (8.0%). Data on mixed features were collected at baseline only and thus do not reflect potential patterns in mixed features within this sample across the study duration. The DSM-5 narrower, non-overlapping definition of mixed episodes resulted in fewer patients who met mixed criteria compared to DSM-IV. Copyright © 2017. Published by Elsevier B.V.

  13. Phosphorylation of the Ndc80 complex protein, HEC1, by Nek2 kinase modulates chromosome alignment and signaling of the spindle assembly checkpoint.

    Science.gov (United States)

    Wei, Randy; Ngo, Bryan; Wu, Guikai; Lee, Wen-Hwa

    2011-10-01

    The spindle assemble checkpoint (SAC) is critical for accurate chromosome segregation. Hec1 contributes to chromosome segregation in part by mediating SAC signaling and chromosome alignment. However, the molecular mechanism by which Hec1 modulates checkpoint signaling and alignment remains poorly understood. We found that Hec1 serine 165 (S165) is preferentially phosphorylated at kinetochores. Phosphorylated Hec1 serine 165 (pS165) specifically localized to kinetochores of misaligned chromosomes, showing a spatiotemporal distribution characteristic of SAC molecules. Expressing an RNA interference (RNAi)-resistant S165A mutant in Hec1-depleted cells permitted normal progression to metaphase, but accelerated the metaphase-to-anaphase transition. The S165A cells were defective in Mad1 and Mad2 localization to kinetochores, regardless of attachment status. These cells often entered anaphase with lagging chromosomes and elicited increased segregation errors and cell death. In contrast, expressing S165E mutant in Hec1-depleted cells triggered defective chromosome alignment and severe mitotic arrest associated with increased Mad1/Mad2 signals at prometaphase kinetochores. A small portion of S165E cells eventually bypassed the SAC but showed severe segregation errors. Nek2 is the primary kinase responsible for kinetochore pS165, while PP1 phosphatase may dephosphorylate pS165 during SAC silencing. Taken together, these results suggest that modifications of Hec1 S165 serve as an important mechanism in modulating SAC signaling and chromosome alignment.

  14. Precise coding of ankle angle and velocity by human calf muscle spindles.

    Science.gov (United States)

    Peters, Ryan M; Dalton, Brian H; Blouin, Jean-Sébastien; Inglis, J Timothy

    2017-05-04

    Human standing balance control requires the integration of sensory feedback to produce anticipatory, stabilizing ankle torques. However, the ability of human triceps surae muscle spindles to provide reliable sensory feedback regarding the small, slow ankle movements that occur during upright standing has recently come under question. We performed microneurography to directly record axon potentials from single muscle spindle afferents in the human triceps surae during servo-controlled movement of the ankle joint. To simulate movements of the ankle while standing, we delivered random 90-s dorsiflexion/plantar flexion oscillations of the ankle joint, with a peak-to-peak amplitude of 0.7° and frequency content below 0.5Hz. In roughly half of the trials (46%), participants held a low-level, near-isometric contraction of the triceps surae muscles. We demonstrate that afferent activity in a population of muscle spindles closely reflects ankle movements at frequencies and amplitudes characteristic of human standing. Four out of five soleus spindles, and three out of seven gastrocnemius spindles coded for at least a single frequency component of anteroposterior ankle rotation. Concatenating within muscles, coherence was significantly greater for soleus spindles at all stimulus frequencies. Voluntary contraction of the parent muscle reduced spindle sensitivity, but only significantly near the mean power frequency of the stimulus (∼0.3Hz). In conclusion, these results provide direct evidence that triceps surae muscle spindles are potentially capable of providing important sensory feedback for the control of human standing balance. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  15. Sleep Spindles in the Right Hemisphere Support Awareness of Regularities and Reflect Pre-Sleep Activations.

    Science.gov (United States)

    Yordanova, Juliana; Kolev, Vasil; Bruns, Eike; Kirov, Roumen; Verleger, Rolf

    2017-11-01

    The present study explored the sleep mechanisms which may support awareness of hidden regularities. Before sleep, 53 participants learned implicitly a lateralized variant of the serial response-time task in order to localize sensorimotor encoding either in the left or right hemisphere and induce implicit regularity representations. Electroencephalographic (EEG) activity was recorded at multiple electrodes during both task performance and sleep, searching for lateralized traces of the preceding activity during learning. Sleep EEG analysis focused on region-specific slow (9-12 Hz) and fast (13-16 Hz) sleep spindles during nonrapid eye movement sleep. Fast spindle activity at those motor regions that were activated during learning increased with the amount of postsleep awareness. Independently of side of learning, spindle activity at right frontal and fronto-central regions was involved: there, fast spindles increased with the transformation of sequence knowledge from implicit before sleep to explicit after sleep, and slow spindles correlated with individual abilities of gaining awareness. These local modulations of sleep spindles corresponded to regions with greater presleep activation in participants with postsleep explicit knowledge. Sleep spindle mechanisms are related to explicit awareness (1) by tracing the activation of motor cortical and right-hemisphere regions which had stronger involvement already during learning and (2) by recruitment of individually consolidated processing modules in the right hemisphere. The integration of different sleep spindle mechanisms with functional states during wake collectively supports the gain of awareness of previously experienced regularities, with a special role for the right hemisphere. © Sleep Research Society 2017. Published by Oxford University Press [on behalf of the Sleep Research Society].

  16. Sleep spindles may predict response to cognitive-behavioral therapy for chronic insomnia.

    Science.gov (United States)

    Dang-Vu, Thien Thanh; Hatch, Benjamin; Salimi, Ali; Mograss, Melodee; Boucetta, Soufiane; O'Byrne, Jordan; Brandewinder, Marie; Berthomier, Christian; Gouin, Jean-Philippe

    2017-11-01

    While cognitive-behavioral therapy for insomnia constitutes the first-line treatment for chronic insomnia, only few reports have investigated how sleep architecture relates to response to this treatment. In this pilot study, we aimed to determine whether pre-treatment sleep spindle density predicts treatment response to cognitive-behavioral therapy for insomnia. Twenty-four participants with chronic primary insomnia participated in a 6-week cognitive-behavioral therapy for insomnia performed in groups of 4-6 participants. Treatment response was assessed using the Pittsburgh Sleep Quality Index and the Insomnia Severity Index measured at pre- and post-treatment, and at 3- and 12-months' follow-up assessments. Secondary outcome measures were extracted from sleep diaries over 7 days and overnight polysomnography, obtained at pre- and post-treatment. Spindle density during stage N2-N3 sleep was extracted from polysomnography at pre-treatment. Hierarchical linear modeling analysis assessed whether sleep spindle density predicted response to cognitive-behavioral therapy. After adjusting for age, sex, and education level, lower spindle density at pre-treatment predicted poorer response over the 12-month follow-up, as reflected by a smaller reduction in Pittsburgh Sleep Quality Index over time. Reduced spindle density also predicted lower improvements in sleep diary sleep efficiency and wake after sleep onset immediately after treatment. There were no significant associations between spindle density and changes in the Insomnia Severity Index or polysomnography variables over time. These preliminary results suggest that inter-individual differences in sleep spindle density in insomnia may represent an endogenous biomarker predicting responsiveness to cognitive-behavioral therapy. Insomnia with altered spindle activity might constitute an insomnia subtype characterized by a neurophysiological vulnerability to sleep disruption associated with impaired responsiveness to

  17. Slow sleep spindle and procedural memory consolidation in patients with major depressive disorder.

    Science.gov (United States)

    Nishida, Masaki; Nakashima, Yusaku; Nishikawa, Toru

    2016-01-01

    Evidence has accumulated, which indicates that, in healthy individuals, sleep enhances procedural memory consolidation, and that sleep spindle activity modulates this process. However, whether sleep-dependent procedural memory consolidation occurs in patients medicated for major depressive disorder remains unclear, as are the pharmacological and physiological mechanisms that underlie this process. Healthy control participants (n=17) and patients medicated for major depressive disorder (n=11) were recruited and subjected to a finger-tapping motor sequence test (MST; nondominant hand) paradigm to compare the averaged scores of different learning phases (presleep, postsleep, and overnight improvement). Participants' brain activity was recorded during sleep with 16 electroencephalography channels (between MSTs). Sleep scoring and frequency analyses were performed on the electroencephalography data. Additionally, we evaluated sleep spindle activity, which divided the spindles into fast-frequency spindle activity (12.5-16 Hz) and slow-frequency spindle activity (10.5-12.5 Hz). Sleep-dependent motor memory consolidation in patients with depression was impaired in comparison with that in control participants. In patients with depression, age correlated negatively with overnight improvement. The duration of slow-wave sleep correlated with the magnitude of motor memory consolidation in patients with depression, but not in healthy controls. Slow-frequency spindle activity was associated with reduction in the magnitude of motor memory consolidation in both groups. Because the changes in slow-frequency spindle activity affected the thalamocortical network dysfunction in patients medicated for depression, dysregulated spindle generation may impair sleep-dependent memory consolidation. Our findings may help to elucidate the cognitive deficits that occur in patients with major depression both in the waking state and during sleep.

  18. Mitosis, diffusible crosslinkers, and the ideal gas law.

    Science.gov (United States)

    Odde, David J

    2015-03-12

    During mitosis, molecular motors hydrolyze ATP to generate sliding forces between adjacent microtubules and form the bipolar mitotic spindle. Lansky et al. now show that the diffusible microtubule crosslinker Ase1p can generate sliding forces between adjacent microtubules, and it does so without ATP hydrolysis. Copyright © 2015 Elsevier Inc. All rights reserved.

  19. Polo-like kinase-1 is a target of the DNA damage checkpoint

    NARCIS (Netherlands)

    Smits, V.A.J.; Klompmaker, R.; Arnaud, L.; Rijksen, G.; Nigg, E.A.; Medema, R.H.

    2000-01-01

    Polo-like kinases (PLKs) have an important role in several stages of mitosis. They contribute to the activation of cyclin B/Cdc2 and are involved in centrosome maturation and bipolar spindle formation at the onset of mitosis1, 2. PLKs also control mitotic exit by regulating the anaphase-promoting

  20. [Thinking organization and defense mechanisms in bipolar disorders. Clinical and psychopathological study on bipolar I and bipolar II].

    Science.gov (United States)

    Lo Baido, Rosa; Di Blasi, Marie; Alfano, Pietro; Audino, Palma; Bellavia, Carmela; Blando, Anna Antonia; Merendino, Adelaide; Messina, Rossana; Poma, Maria Luisa; La Grutta, Sabina

    2013-01-01

    The aim of this research is to explore the psychical functioning in bipolar I or bipolar II disorder people through the analysis and comparison of their thought styles and defense patterns. 29 bipolar I and bipolar II people afferent to Palermo University Policlinical Psychriatic Hospital Department were selected during the whole 2009-2010 year. The following tests were administred: Wechsler Adult Intelligent Scale-R (WAIS-R) in order to measure the general cognitive function; Defense Mechanisms Inventory (DMI) in order to measure defense patterns. Afterwards, the results of the two tests were analysed and compared. Bipolar disorder people use cognitive mechanisms and defense strategies that are very different from standard population. Bipolar I subjects show both wider and more serious cognitive deterioration and stricter defense mechanisms than bipolar II subjects. Generally bipolar patients show an immature personality based on archaic mechanisms that can be found in all the spheres of their personality: emotions, cognition, Ego-strength, adaptability to reality. The peculiar achieved cognitive and defense profile leads to important considerations about how psychological strategies can contribute to use "bespoke" treatments for these patients.

  1. The Contribution of Thalamocortical Core and Matrix Pathways to Sleep Spindles

    Directory of Open Access Journals (Sweden)

    Giovanni Piantoni

    2016-01-01

    Full Text Available Sleep spindles arise from the interaction of thalamic and cortical neurons. Neurons in the thalamic reticular nucleus (TRN inhibit thalamocortical neurons, which in turn excite the TRN and cortical neurons. A fundamental principle of anatomical organization of the thalamocortical projections is the presence of two pathways: the diffuse matrix pathway and the spatially selective core pathway. Cortical layers are differentially targeted by these two pathways with matrix projections synapsing in superficial layers and core projections impinging on middle layers. Based on this anatomical observation, we propose that spindles can be classified into two classes, those arising from the core pathway and those arising from the matrix pathway, although this does not exclude the fact that some spindles might combine both pathways at the same time. We find evidence for this hypothesis in EEG/MEG studies, intracranial recordings, and computational models that incorporate this difference. This distinction will prove useful in accounting for the multiple functions attributed to spindles, in that spindles of different types might act on local and widespread spatial scales. Because spindle mechanisms are often hijacked in epilepsy and schizophrenia, the classification proposed in this review might provide valuable information in defining which pathways have gone awry in these neurological disorders.

  2. Sleep spindles are related to schizotypal personality traits and thalamic glutamine/glutamate in healthy subjects.

    Science.gov (United States)

    Lustenberger, Caroline; O'Gorman, Ruth L; Pugin, Fiona; Tüshaus, Laura; Wehrle, Flavia; Achermann, Peter; Huber, Reto

    2015-03-01

    Schizophrenia is a severe mental disorder affecting approximately 1% of the worldwide population. Yet, schizophrenia-like experiences (schizotypy) are very common in the healthy population, indicating a continuum between normal mental functioning and the psychosis found in schizophrenic patients. A continuum between schizotypy and schizophrenia would be supported if they share the same neurobiological origin. Two such neurobiological markers of schizophrenia are: (1) a reduction of sleep spindles (12-15 Hz oscillations during nonrapid eye movement sleep), likely reflecting deficits in thalamo-cortical circuits and (2) increased glutamine and glutamate (Glx) levels in the thalamus. Thus, this study aimed to investigate whether sleep spindles and Glx levels are related to schizotypal personality traits in healthy subjects. Twenty young male subjects underwent 2 all-night sleep electroencephalography recordings (128 electrodes). Sleep spindles were detected automatically. After those 2 nights, thalamic Glx levels were measured by magnetic resonance spectroscopy. Subjects completed a magical ideation scale to assess schizotypy. Sleep spindle density was negatively correlated with magical ideation (r = -.64, P .1). The common relationship of sleep spindle density with schizotypy and thalamic Glx levels indicates a neurobiological overlap between nonclinical schizotypy and schizophrenia. Thus, sleep spindle density and magical ideation may reflect the anatomy and efficiency of the thalamo-cortical system that shows pronounced impairment in patients with schizophrenia. © The Author 2014. Published by Oxford University Press on behalf of the Maryland Psychiatric Research Center. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  3. Fast and slow spindle involvement in the consolidation of a new motor sequence.

    Science.gov (United States)

    Barakat, M; Doyon, J; Debas, K; Vandewalle, G; Morin, A; Poirier, G; Martin, N; Lafortune, M; Karni, A; Ungerleider, L G; Benali, H; Carrier, J

    2011-02-02

    This study aimed to determine the distinct contribution of slow (11-13 Hz) and fast (13-15 Hz) spindles in the consolidation process of a motor sequence learning task (MSL). Young subjects (n = 12) were trained on both a finger MSL task and a control (CTRL) condition, which were administered one week apart in a counterbalanced order. Subjects were asked to practice the MSL or CTRL task in the evening (approximately 9:00 p.m.) and their performance was retested on the same task 12h later (approximately 9:00 a.m.). Polysomnographic (PSG) recordings were performed during the night following training on either task, and an automatic algorithm was used to detect fast and slow spindles and to quantify their characteristics (i.e., density, amplitude, and duration). Statistical analyses revealed higher fast (but not slow) spindle density after training on the MSL than after practice of the CTRL task. The increase in fast spindle density on the MSL task correlated positively with overnight performance gains on the MSL task and with difference in performance gain between the MSL and CTRL tasks. Together, these results suggest that fast sleep spindles help activate the cerebral network involved in overnight MSL consolidation, while slow spindles do not appear to play a role in this mnemonic process. Copyright © 2010 Elsevier B.V. All rights reserved.

  4. On the Free Vibration Modeling of Spindle Systems: A Calibrated Dynamic Stiffness Matrix

    Directory of Open Access Journals (Sweden)

    Omar Gaber

    2014-01-01

    Full Text Available The effect of bearings on the vibrational behavior of machine tool spindles is investigated. This is done through the development of a calibrated dynamic stiffness matrix (CDSM method, where the bearings flexibility is represented by massless linear spring elements with tuneable stiffness. A dedicated MATLAB code is written to develop and to assemble the element stiffness matrices for the system’s multiple components and to apply the boundary conditions. The developed method is applied to an illustrative example of spindle system. When the spindle bearings are modeled as simply supported boundary conditions, the DSM model results in a fundamental frequency much higher than the system’s nominal value. The simply supported boundary conditions are then replaced by linear spring elements, and the spring constants are adjusted such that the resulting calibrated CDSM model leads to the nominal fundamental frequency of the spindle system. The spindle frequency results are also validated against the experimental data. The proposed method can be effectively applied to predict the vibration characteristics of spindle systems supported by bearings.

  5. Sleep Spindle Characteristics in Children with Neurodevelopmental Disorders and Their Relation to Cognition

    Science.gov (United States)

    Wise, Merrill S.

    2016-01-01

    Empirical evidence indicates that sleep spindles facilitate neuroplasticity and “off-line” processing during sleep, which supports learning, memory consolidation, and intellectual performance. Children with neurodevelopmental disorders (NDDs) exhibit characteristics that may increase both the risk for and vulnerability to abnormal spindle generation. Despite the high prevalence of sleep problems and cognitive deficits in children with NDD, only a few studies have examined the putative association between spindle characteristics and cognitive function. This paper reviews the literature regarding sleep spindle characteristics in children with NDD and their relation to cognition in light of what is known in typically developing children and based on the available evidence regarding children with NDD. We integrate available data, identify gaps in understanding, and recommend future research directions. Collectively, studies are limited by small sample sizes, heterogeneous populations with multiple comorbidities, and nonstandardized methods for collecting and analyzing findings. These limitations notwithstanding, the evidence suggests that future studies should examine associations between sleep spindle characteristics and cognitive function in children with and without NDD, and preliminary findings raise the intriguing question of whether enhancement or manipulation of sleep spindles could improve sleep-dependent memory and other aspects of cognitive function in this population. PMID:27478646

  6. A Novel Visualization Method for Sleep Spindles Based on Source Localization of High Density EEG.

    Science.gov (United States)

    Lee, Soohyun; Kim, Seunghwan; Choi, Jee Hyun

    2017-12-01

    Equivalent dipole source localization is a well-established approach to localizing the electrical activity in electroencephalogram (EEG). So far, source localization has been used primarily in localizing the epileptic source in human epileptic patients. Currently, source localization techniques have been applied to account for localizing epileptic source among the epileptic patients. Here, we present the first application of source localization in the field of sleep spindle in mouse brain. The spatial distribution of cortical potential was obtained by high density EEG and then the anterior and posterior sleep spindles were classified based on the K-mean clustering algorithm. To solve the forward problem, a realistic geometry brain model was produced based on boundary element method (BEM) using mouse MRI. Then, we applied four different source estimation algorithms (minimum norm, eLORETA, sLORETA, and LORETA) to estimate the spatial location of equivalent dipole source of sleep spindles. The estimated sources of anterior and posterior spindles were plotted in a cine-mode that revealed different topographic patterns of spindle propagation. The characterization of sleep spindles may be better be distinguished by our novel visualization method.

  7. Novel muscle spindles containing muscle fibers devoid of sensory innervation in the extensor digitorum longus muscle of aged rats.

    Science.gov (United States)

    Desaki, Junzo; Nishida, Naoya

    2008-04-01

    We examined the structural features of muscle spindles at the equatorial and juxtaequatorial regions in the extensor digitorum longus muscle of adult (12 months) and aged (25 months) rats. In aged muscle spindles, the lamellated layers of the spindle capsule were a little increased in number compared to those in the adult ones. Two novel muscle spindles were observed in the aged muscle. In one muscle spindle, the spindle capsule contained four thin intrafusal muscle fibers invested by the inner capsule and two muscle fibers between the layers of the spindle capsule. Serial semithin sections revealed that the latter lacked the investment of the spindle capsule at the polar region. The other muscle spindle contained four intrafusal muscle fibers: two thin sensory-innervated muscle fibers invested by the inner capsule and two thick muscle fibers similar in structural features to neighboring extrafusal muscle fibers and lacking sensory innervation within the wide periaxial space. These findings suggest that two muscle fibers between the layers of the spindle capsule may be invested by the newly formed capsular cells during aging, while two thick fibers within the periaxial space may fail to receive the sensory innervation during the early development and follow the course of extrafusal fiber differentiation.

  8. SMC complexes orchestrate the mitotic chromatin interaction landscape.

    Science.gov (United States)

    Kakui, Yasutaka; Uhlmann, Frank

    2017-09-21

    Chromatin is a very long DNA-protein complex that controls the expression and inheritance of the genetic information. Chromatin is stored within the nucleus in interphase and further compacted into chromosomes during mitosis. This process, known as chromosome condensation, is essential for faithful segregation of genomic DNA into daughter cells. Condensin and cohesin, members of the structural maintenance of chromosomes (SMC) family, are fundamental for chromosome architecture, both for establishment of chromatin structure in the interphase nucleus and for the formation of condensed chromosomes in mitosis. These ring-shaped SMC complexes are thought to regulate the interactions between DNA strands by topologically entrapping DNA. How this activity shapes chromosomes is not yet understood. Recent high throughput chromosome conformation capture studies revealed how chromatin is reorganized during the cell cycle and have started to explore the role of SMC complexes in mitotic chromatin architecture. Here, we summarize these findings and discuss the conserved nature of chromosome condensation in eukaryotes. We highlight the unexpected finding that condensin-dependent intra-chromosomal interactions in mitosis increase within a distinctive distance range that is characteristic for an organism, while longer and shorter-range interactions are suppressed. This reveals important molecular insight into chromosome architecture.

  9. X-ray induction of mitotic and meiotic chromosome aberrations

    International Nuclear Information System (INIS)

    Yao, K.T.S.

    1980-01-01

    In 1964 six pairs of rat kangaroo (Potorous tridactylis) were obtained from Australia. The tissues of these animals were used to initiate cell lines. Since this species has a low chromosome number of six pairs, each pair with its own distinctive morphology, it is particularly favorable for cytogenetic research. In cell cultures derived from the corneal endothelial tissues of one animal there emerged a number of haploid cells. The number of haploid cells in the cultures reached as high as 20% of the total mitotic configurations. The in vitro diploid and haploid mixture cell cultures could be a resemblance or a coincidence to the mixture existence of the diploid primary spermatocytes and the haploid secondary spermatocytes (gametes) in the in vivo testicular tissues of the male animals. It would be interesting to compare reactions of the haploid and diploid cell mixture, either in the cultures or in the testes, to x-ray exposure. Two other studies involving x-ray effects on Chinese hamster oocyte maturation and meiotic chromosomes and the x-ray induction of Chinese hamster spermatocyte meiotic chromosome aberrations have been done in this laboratory. A review of these three studies involving diploid and haploid chromosomes may lead to further research in the x-ray induction of chromosome aberrations

  10. Phosphorylation and disassembly of intermediate filaments in mitotic cells

    International Nuclear Information System (INIS)

    Chou, Yinghao; Rosevear, E.; Goldman, R.D.

    1989-01-01

    As baby hamster kidney (BHK-21) cells enter mitosis, networks of intermediate filaments (IFs) are transformed into cytoplasmic aggregates of protofilaments. Coincident with this morphological change, the phosphate content of vimentin increases from 0.3 mol of P i per mol of protein in interphase to 1.9 mol of P i per mol of protein in mitosis. A similar increase in phosphate content is observed with desmin, from 0.5 mol of P i per mol of protein to 1.5 mol of P i per mol of protein. Fractionation of mitotic cell lysates by hydroxylapatite column chromatography reveals the presence of two IF protein kinase activities, designated as IF protein kinase I and IF protein kinase II. Comparison of two-dimensional 32 P-labeled phosphopeptide maps of vimentin and desmin phosphorylated in vivo in mitosis, and in vitro using partially purified kinase fractions, reveals extensive similarity in the two sets of phosphorylation sites. Phosphorylation of in vitro polymerized IFs by IF protein kinase II induces complete disassembly as determined by negative-stain electron microscopy. The results support the idea that the disassembly of IFs in mitosis is regulated by the phosphorylation of its subunit proteins

  11. Citron kinase - renaissance of a neglected mitotic kinase.

    Science.gov (United States)

    D'Avino, Pier Paolo

    2017-05-15

    Cell division controls the faithful segregation of genomic and cytoplasmic materials between the two nascent daughter cells. Members of the Aurora, Polo and cyclin-dependent (Cdk) kinase families are known to regulate multiple events throughout cell division, whereas another kinase, citron kinase (CIT-K), for a long time has been considered to function solely during cytokinesis, the last phase of cell division. CIT-K was originally proposed to regulate the ingression of the cleavage furrow that forms at the equatorial cortex of the dividing cell after chromosome segregation. However, studies in the last decade have clarified that this kinase is, instead, required for the organization of the midbody in late cytokinesis, and also revealed novel functions of CIT-K earlier in mitosis and in DNA damage control. Moreover, CIT-K mutations have recently been linked to the development of human microcephaly, and CIT-K has been identified as a potential target in cancer therapy. In this Commentary, I describe and re-evaluate the functions and regulation of CIT-K during cell division and its involvement in human disease. Finally, I offer my perspectives on the open questions and future challenges that are necessary to address, in order to fully understand this important and yet unjustly neglected mitotic kinase. © 2017. Published by The Company of Biologists Ltd.

  12. Maintaining Genome Stability in Defiance of Mitotic DNA Damage

    Science.gov (United States)

    Ferrari, Stefano; Gentili, Christian

    2016-01-01

    The implementation of decisions affecting cell viability and proliferation is based on prompt detection of the issue to be addressed, formulation and transmission of a correct set of instructions and fidelity in the execution of orders. While the first and the last are purely mechanical processes relying on the faithful functioning of single proteins or macromolecular complexes (sensors and effectors), information is the real cue, with signal amplitude, duration, and frequency ultimately determining the type of response. The cellular response to DNA damage is no exception to the rule. In this review article we focus on DNA damage responses in G2 and Mitosis. First, we set the stage describing mitosis and the machineries in charge of assembling the apparatus responsible for chromosome alignment and segregation as well as the inputs that control its function (checkpoints). Next, we examine the type of issues that a cell approaching mitosis might face, presenting the impact of post-translational modifications (PTMs) on the correct and timely functioning of pathways correcting errors or damage before chromosome segregation. We conclude this essay with a perspective on the current status of mitotic signaling pathway inhibitors and their potential use in cancer therapy. PMID:27493659

  13. Age-related Changes In Sleep Spindles Characteristics During Daytime Recovery Following a 25-Hour Sleep Deprivation

    Directory of Open Access Journals (Sweden)

    Thaïna eRosinvil

    2015-06-01

    Full Text Available Objectives: The mechanisms underlying sleep spindles (~11-15Hz; >0.5s help to protect sleep. With age, it becomes increasingly difficult to maintain sleep at a challenging time (e.g. daytime, even after sleep loss. This study compared spindle characteristics during daytime recovery and nocturnal sleep in young and middle-aged adults. In addition, we explored whether spindles characteristics in baseline nocturnal sleep were associated with the ability to maintain sleep during daytime recovery periods in both age groups.Methods: Twenty-nine young (15 women and 14 men; 27.3 ± 5.0 and 31 middle-aged (19 women and 13 men; 51.6 y ± 5.1 healthy subjects participated in a baseline nocturnal sleep and a daytime recovery sleep after 25 hours of sleep deprivation. Spindles were detected on artefact-free NREM sleep epochs. Spindle density (nb/min, amplitude (μV, frequency (Hz and duration (s were analyzed on parasagittal (linked-ears derivations. Results: In young subjects, spindle frequency increased during daytime recovery sleep as compared to baseline nocturnal sleep in all derivations, whereas middle-aged subjects showed spindle frequency enhancement only in the prefrontal derivation. No other significant interaction between age group and sleep condition was observed. Spindle density for all derivations and centro-occipital spindle amplitude decreased whereas prefrontal spindle amplitude increased from baseline to daytime recovery sleep in both age groups. Finally, no significant correlation was found between spindle characteristics during baseline nocturnal sleep and the marked reduction in sleep efficiency during daytime recovery sleep in both young and middle-aged subjects.Conclusion: These results suggest that the interaction between homeostatic and circadian pressure module spindle frequency differently in aging. Spindle characteristics do not seem to be linked with the ability to maintain daytime recovery sleep.

  14. Histone phosphorylation during radiation-induced mitotic delay in synchronous plasmodia of Physarum polycephalum

    International Nuclear Information System (INIS)

    Brewer, E.N.; Oleinick, N.L.

    1980-01-01

    Using the nearly perfect synchrony of the mitotic stages in Physarum plasmodia, and making use of 32 P as a tracer, studies were made to define the time course of histone phosphorylation during the late G2 and prophase and the alterations in that time course accompanying radiation-induced mitotic delay. Histone H1 was phosphorylated throughout the last 2-3 hours of the mitotic cycle coincident with the early stages of chromosome condensation. H1 phosphorylation appeared to be reduced in irradiated plasmodia. It is postulated that a longer time period, i.e. the mitotic delay, may be required to obtain the same eventual level of H1-phosphate. In normal cultures, nucleosome core histones were phosphorylated late in G2 and prophase, the peak corresponding closely with the γ-transition point. In irradiated plasmodia, phosphorylation of the core histones had an extended time course similar to H1. (U.K.)

  15. Poorer sustained attention in bipolar I than bipolar II disorder

    Directory of Open Access Journals (Sweden)

    Chen Shih-Heng

    2010-02-01

    Full Text Available Abstract Background Nearly all information processing during cognitive processing takes place during periods of sustained attention. Sustained attention deficit is among the most commonly reported impairments in bipolar disorder (BP. The majority of previous studies have only focused on bipolar I disorder (BP I, owing to underdiagnosis or misdiagnosis of bipolar II disorder (BP II. With the refinement of the bipolar spectrum paradigm, the goal of this study was to compare the sustained attention of interepisode patients with BP I to those with BP II. Methods In all, 51 interepisode BP patients (22 with BP I and 29 with BP II and 20 healthy controls participated in this study. The severity of psychiatric symptoms was assessed by the 17-item Hamilton Depression Rating Scale and the Young Mania Rating Scale. All participants undertook Conners' Continuous Performance Test II (CPT-II to evaluate sustained attention. Results After controlling for the severity of symptoms, age and years of education, BP I patients had a significantly longer reaction times (F(2,68 = 7.648, P = 0.001, worse detectability (d' values (F(2,68 = 6.313, P = 0.003 and more commission errors (F(2,68 = 6.182, P = 0.004 than BP II patients and healthy controls. BP II patients and controls scored significantly higher than BP I patients for d' (F = 6.313, P = 0.003. No significant difference was found among the three groups in omission errors and no significant correlations were observed between CPT-II performance and clinical characteristics in the three groups. Conclusions These findings suggested that impairments in sustained attention might be more representative of BP I than BP II after controlling for the severity of symptoms, age, years of education and reaction time on the attentional test. A longitudinal follow-up study design with a larger sample size might be needed to provide more information on chronological sustained attention deficit in BP patients, and to illustrate

  16. Ion pump using cylindrically symmetric spindle magnetic field

    Science.gov (United States)

    Rashid, M. H.

    2012-11-01

    For all accelerators and many research and industries, excellent vacuum conditions are required and the highest possible pumping rates are necessary. For most applications the standard ion sputtering pump (ISP) meets these requirements and is optimal for financial point of view also. The physical principle of the ISP is well known and many companies manufacture variety of ISP. Most of them use dipole magnetic field produced by permanent magnet and electric dipole field between the electrodes in which tenuous plasma is created because of interaction of between the relatively fast electrons slow residual gas atoms. Performance of an ISP depends basically on the electron cloud density in between the titanium electrodes but in the available present configurations no consideration has been given to electron confinement which needs a mirror magnetic field. If this is incorporated it will make a robust ISP surely; furthermore, the requirement of constant feeding of high voltage to electrodes for supplying sufficient number of electrons will be reduced too. A study has been performed to create sufficient rotationally symmetric spindle magnetic field (SMF) with inherent presence of magnetic mirror effect to electron motion to confine them for longer time for enhancing the density of electron cloud between the electrodes. It will lessen the electric power feeding the electrodes and lengthen their life-time. Construction of further compact and robust ISP is envisaged herein. The field simulation using the commercially available permanent magnet together with simulation of electron motion in such field will be presented and discussed in the paper.

  17. Sleep spindles in midday naps enhance learning in preschool children.

    Science.gov (United States)

    Kurdziel, Laura; Duclos, Kasey; Spencer, Rebecca M C

    2013-10-22

    Despite the fact that midday naps are characteristic of early childhood, very little is understood about the structure and function of these sleep bouts. Given that sleep benefits memory in young adults, it is possible that naps serve a similar function for young children. However, children transition from biphasic to monophasic sleep patterns in early childhood, eliminating the nap from their daily sleep schedule. As such, naps may contain mostly light sleep stages and serve little function for learning and memory during this transitional age. Lacking scientific understanding of the function of naps in early childhood, policy makers may eliminate preschool classroom nap opportunities due to increasing curriculum demands. Here we show evidence that classroom naps support learning in preschool children by enhancing memories acquired earlier in the day compared with equivalent intervals spent awake. This nap benefit is greatest for children who nap habitually, regardless of age. Performance losses when nap-deprived are not recovered during subsequent overnight sleep. Physiological recordings of naps support a role of sleep spindles in memory performance. These results suggest that distributed sleep is critical in early learning; when short-term memory stores are limited, memory consolidation must take place frequently.

  18. The relationship between mitotic rate and depth of invasion in biopsies of malignant melanoma

    Directory of Open Access Journals (Sweden)

    Ghasemi Basir HR

    2018-03-01

    Full Text Available Hamid Reza Ghasemi Basir,1,2 Pedram Alirezaei,2 Sara Ahovan,3 Abbas Moradi3 1Department of Pathology, School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran; 2Psoriasis Research Center, Hamadan University of Medical Sciences, Hamadan, Iran; 3School of Medicine, Hamadan University of Medical Sciences, Hamadan, Iran Background: Malignant melanoma of the skin is a potentially lethal neoplasm that generally originates from atypical melanocytes in the dermal–epidermal junction. When the neoplasm penetrates into the dermis, several variables can affect the extent of its spread, among which depth of invasion has the most important prognostic value. Mitotic rate is another prognostic factor that reflects the biological behavior of the neoplasm.Objective: This study was designed to evaluate the probable relationship between the depth of invasion of malignant melanoma and its mitotic rate.Materials and methods: This study was performed on 50 excisional biopsy specimens that had received the diagnosis of malignant melanoma histopathologically. Tumor characteristics including Breslow thickness, Clark level, T-stage, and tumor mitotic rate were recorded.Results: We observed that at higher Clark levels and higher T-stages, and the mean mitotic rate was significantly increased. Moreover, there was a positive and significant correlation between Breslow thickness and mitotic rate. We demonstrated that one unit increase in mitotic rate was correlated with 0.8 mm increase in Breslow thickness of the tumor.Conclusion: In malignant melanoma, mitotic activity may probably indicate the depth of tumor invasion. Therefore, in incisional biopsies where depth of invasion cannot be accurately determined, the mitotic activity may be used to estimate Breslow thickness, which is necessary for planning surgical management. Keywords: melanoma, mitosis, Breslow, invasion, thickness, proliferation

  19. The Spoilage Yeast Zygosaccharomyces bailii Forms Mitotic Spores: a Screening Method for Haploidization

    OpenAIRE

    Rodrigues, Fernando; Ludovico, Paula; Sousa, Maria João; Steensma, H. Yde; Côrte-Real, Manuela; Leão, Cecília

    2003-01-01

    Zygosaccharomyces bailii ISA 1307 and the type strain of this spoilage yeast show a diploid DNA content. Together with a rather peculiar life cycle in which mitotic but no meiotic spores appear to be formed, the diploid DNA content explains the observed difficulties in obtaining auxotrophic mutants. Mitotic chromosome loss induced by benomyl and selection on canavanine media resulted in three haploid strains of Z. bailii. This new set of Z. bailii strains allows the easy isolation...

  20. Mitotically Active Leiomyoma of the Uterus in a Postmenopausal Breast Cancer Patient Receiving Tamoxifen

    OpenAIRE

    I-Feng Liu; Yu-Shan Yen; Ya-Min Cheng; Cheng-Yang Chou

    2006-01-01

    Objective: Mitotically active leiomyoma of the uterus complicated with postmenopausal vaginal bleeding has never been reported in Taiwan. Here, we present a case of mitotically active leiomyoma of the uterus complicated with postmenopausal vaginal bleeding in a breast cancer patient who had been receiving tamoxifen for 2 years Case Report: A 56-year-old woman visited our clinic due to abnormal vaginal spotting for 3 months. This patient had been menopausal for about 6 years without hormone...

  1. Effects of polyamines and polyamine biosynthetic inhibitors on mitotic activity of Allium cepa root tips.

    Science.gov (United States)

    Unal, Meral; Palavan-Unsal, Narcin; Tufekci, M A

    2008-03-01

    The genotoxic and cytotoxic effects of exogenous polyamines (PAs), putrescine (Put), spermidine (Spd), spermine (Spm) and PA biosynthetic inhibitors, alpha-difluoromethylornithine (DFMO), cyclohexilamine (CHA), methylglioxal bis-(guanylhydrazone) (MGBG) were investigated in the root meristems of Allium cepa L. The reduction of mitotic index and the induction of chromosomal aberrations such as bridges, stickiness, c-mitotic anaphases, micronuclei, endoredupliction by PAs and PA biosynthetic inhibitors were observed and these were used as evidence of genotoxicity and cytotoxicity.

  2. Swimming in Deep Water: Childhood Bipolar Disorder

    Science.gov (United States)

    Senokossoff, Gwyn W.; Stoddard, Kim

    2009-01-01

    The authors focused on one parent's struggles in finding a diagnosis and intervention for a child who had bipolar disorder. The authors explain the process of identification, diagnosis, and intervention of a child who had bipolar disorder. In addition to the personal story, the authors provide information on the disorder and outline strategies…

  3. Bipolar disorder diagnosis: challenges and future directions

    Science.gov (United States)

    Phillips, Mary L; Kupfer, David J

    2018-01-01

    Bipolar disorder refers to a group of affective disorders, which together are characterised by depressive and manic or hypomanic episodes. These disorders include: bipolar disorder type I (depressive and manic episodes: this disorder can be diagnosed on the basis of one manic episode); bipolar disorder type II (depressive and hypomanic episodes); cyclothymic disorder (hypomanic and depressive symptoms that do not meet criteria for depressive episodes); and bipolar disorder not otherwise specified (depressive and hypomanic-like symptoms that do not meet the diagnostic criteria for any of the aforementioned disorders). Bipolar disorder type II is especially difficult to diagnose accurately because of the difficulty in differentiation of this disorder from recurrent unipolar depression (recurrent depressive episodes) in depressed patients. The identification of objective biomarkers that represent pathophysiologic processes that differ between bipolar disorder and unipolar depression can both inform bipolar disorder diagnosis and provide biological targets for the development of new and personalised treatments. Neuroimaging studies could help the identification of biomarkers that differentiate bipolar disorder from unipolar depression, but the problem in detection of a clear boundary between these disorders suggests that they might be better represented as a continuum of affective disorders. Innovative combinations of neuroimaging and pattern recognition approaches can identify individual patterns of neural structure and function that accurately ascertain where a patient might lie on a behavioural scale. Ultimately, an integrative approach, with several biological measurements using different scales, could yield patterns of biomarkers (biosignatures) to help identify biological targets for personalised and new treatments for all affective disorders. PMID:23663952

  4. Transient Stuttering in Catatonic Bipolar Patients

    Directory of Open Access Journals (Sweden)

    Anthony B. Joseph

    1991-01-01

    Full Text Available Two cases of transient stuttering occurring in association with catatonia and bipolar disorder are described. Affective decompensation has been associated with lateralized cerebral dysfunction, and it is hypothesized that in some bipolar catatonic patients a concomitant disorder of the lateralization of language function may lead to a variety of clinical presentations including aphasia, mutism, and stuttering.

  5. Cognitive behavioral therapy for bipolar disorders

    OpenAIRE

    Lotufo Neto, Francisco

    2004-01-01

    Descrição dos objetivos e principais técnicas da terapia comportamental cognitiva usadas para a psicoterapia das pessoas com transtorno bipolar.Objectives and main techniques of cognitive behavior therapy for the treatment of bipolar disorder patients are described.

  6. NO signaling in retinal bipolar cells.

    Science.gov (United States)

    Agurto, A; Vielma, A H; Cadiz, B; Couve, E; Schmachtenberg, O

    2017-08-01

    Nitric oxide (NO) is a neuromodulator involved in physiological and pathological processes in the retina. In the inner retina, a subgroup of amacrine cells have been shown to synthesize NO, but bipolar cells remain controversial as NO sources. This study correlates NO synthesis in dark-adapted retinas, through labeling with the NO marker DAF-FM, with neuronal nitric oxide synthase (nNOS) and inducible NOS expression, and presence of the NO receptor soluble guanylate cyclase in bipolar cells. NO containing bipolar cells were morphologically identified by dialysis of DAF fluorescent cells with intracellular dyes, or by DAF labeling followed by immunohistochemistry for nNOS and other cellular markers. DAF fluorescence was observed in all types of bipolar cells that could be identified, but the most intense DAF fluorescence was observed in bipolar cells with severed processes, supporting pathological NO signaling. Among nNOS expressing bipolar cells, type 9 was confirmed unequivocally, while types 2, 3a, 3b, 4, 5, 7, 8 and the rod bipolar cell were devoid of this enzyme. These results establish specific bipolar cell types as NO sources in the inner retina, and support the involvement of NO signaling in physiological and pathological processes in the inner retina. Copyright © 2017 Elsevier Ltd. All rights reserved.

  7. A mathematical model of mitotic exit in budding yeast: the role of Polo kinase.

    Directory of Open Access Journals (Sweden)

    Baris Hancioglu

    Full Text Available Cell cycle progression in eukaryotes is regulated by periodic activation and inactivation of a family of cyclin-dependent kinases (Cdk's. Entry into mitosis requires phosphorylation of many proteins targeted by mitotic Cdk, and exit from mitosis requires proteolysis of mitotic cyclins and dephosphorylation of their targeted proteins. Mitotic exit in budding yeast is known to involve the interplay of mitotic kinases (Cdk and Polo kinases and phosphatases (Cdc55/PP2A and Cdc14, as well as the action of the anaphase promoting complex (APC in degrading specific proteins in anaphase and telophase. To understand the intricacies of this mechanism, we propose a mathematical model for the molecular events during mitotic exit in budding yeast. The model captures the dynamics of this network in wild-type yeast cells and 110 mutant strains. The model clarifies the roles of Polo-like kinase (Cdc5 in the Cdc14 early anaphase release pathway and in the G-protein regulated mitotic exit network.

  8. Phosphorylation of XIAP by CDK1–cyclin-B1 controls mitotic cell death

    Science.gov (United States)

    Hou, Ying; Allan, Lindsey A.

    2017-01-01

    ABSTRACT Regulation of cell death is crucial for the response of cancer cells to drug treatments that cause arrest in mitosis, and is likely to be important for protection against chromosome instability in normal cells. Prolonged mitotic arrest can result in cell death by activation of caspases and the induction of apoptosis. Here, we show that X-linked inhibitor of apoptosis (XIAP) plays a key role in the control of mitotic cell death. Ablation of XIAP expression sensitises cells to prolonged mitotic arrest caused by a microtubule poison. XIAP is stable during mitotic arrest, but its function is controlled through phosphorylation by the mitotic kinase CDK1–cyclin-B1 at S40. Mutation of S40 to a phosphomimetic residue (S40D) inhibits binding to activated effector caspases and abolishes the anti-apoptotic function of XIAP, whereas a non-phosphorylatable mutant (S40A) blocks apoptosis. By performing live-cell imaging, we show that phosphorylation of XIAP reduces the threshold for the onset of cell death in mitosis. This work illustrates that mitotic cell death is a form of apoptosis linked to the progression of mitosis through control by CDK1–cyclin-B1. PMID:27927753

  9. Identification of Mitosis-Specific Phosphorylation in Mitotic Chromosome-Associated Proteins.

    Science.gov (United States)

    Ohta, Shinya; Kimura, Michiko; Takagi, Shunsuke; Toramoto, Iyo; Ishihama, Yasushi

    2016-09-02

    During mitosis, phosphorylation of chromosome-associated proteins is a key regulatory mechanism. Mass spectrometry has been successfully applied to determine the complete protein composition of mitotic chromosomes, but not to identify post-translational modifications. Here, we quantitatively compared the phosphoproteome of isolated mitotic chromosomes with that of chromosomes in nonsynchronized cells. We identified 4274 total phosphorylation sites and 350 mitosis-specific phosphorylation sites in mitotic chromosome-associated proteins. Significant mitosis-specific phosphorylation in centromere/kinetochore proteins was detected, although the chromosomal association of these proteins did not change throughout the cell cycle. This mitosis-specific phosphorylation might play a key role in regulation of mitosis. Further analysis revealed strong dependency of phosphorylation dynamics on kinase consensus patterns, thus linking the identified phosphorylation sites to known key mitotic kinases. Remarkably, chromosomal axial proteins such as non-SMC subunits of condensin, TopoIIα, and Kif4A, together with the chromosomal periphery protein Ki67 involved in the establishment of the mitotic chromosomal structure, demonstrated high phosphorylation during mitosis. These findings suggest a novel mechanism for regulation of chromosome restructuring in mitosis via protein phosphorylation. Our study generated a large quantitative database on protein phosphorylation in mitotic and nonmitotic chromosomes, thus providing insights into the dynamics of chromatin protein phosphorylation at mitosis onset.

  10. The elusive role of mitotic bookmarking in transcriptional regulation: Insights from Sox2.

    Science.gov (United States)

    Deluz, Cédric; Strebinger, Daniel; Friman, Elias T; Suter, David M

    2017-04-03

    The ability of some transcription factors to remain bound to specific genes on condensed mitotic chromosomes has been suggested to play a role in their rapid transcriptional reactivation upon mitotic exit. We have recently shown that SOX2 and OCT4 remain associated to mitotic chromosomes, and that depletion of SOX2 at the mitosis-G1 (M-G1) transition impairs its ability to maintain pluripotency and drive neuroectodermal commitment. Here we report on the role of SOX2 at the M-G1 transition in regulating transcriptional activity of embryonic stem cells. Using single cell time-lapse analysis of reporter constructs for STAT3 and SOX2/OCT4 activity, we show that SOX2/OCT4 do not lead to more rapid transcriptional reactivation in G1 than STAT3, a transcription factor that is excluded from mitotic chromosomes. We also report that only few endogenous target genes show decreased pre-mRNA levels after mitotic exit or in other cell cycle phases in the absence of SOX2 at the M-G1 transition. This suggests that bookmarked SOX2 target genes are not differently regulated than non-bookmarked target genes, and we discuss an alternative hypothesis on how mitotic bookmarking by SOX2 and other sequence-specific transcription factors could be involved in transcriptional regulation.

  11. Co-delivery of paclitaxel and cetuximab by nanodiamond enhances mitotic catastrophe and tumor inhibition.

    Science.gov (United States)

    Lin, Yu-Wei; Raj, Emmanuel Naveen; Liao, Wei-Siang; Lin, Johnson; Liu, Kuang-Kai; Chen, Ting-Hua; Cheng, Hsiao-Chun; Wang, Chi-Ching; Li, Lily Yi; Chen, Chinpiao; Chao, Jui-I

    2017-08-29

    The poor intracellular uptake and non-specific binding of anticancer drugs into cancer cells are the bottlenecks in cancer therapy. Nanocarrier platforms provide the opportunities to improve the drug efficacy. Here we show a carbon-based nanomaterial nanodiamond (ND) that carried paclitaxel (PTX), a microtubule inhibitor, and cetuximab (Cet), a specific monoclonal antibody against epidermal growth factor receptor (EGFR), inducing mitotic catastrophe and tumor inhibition in human colorectal cancer (CRC). ND-PTX blocked the mitotic progression, chromosomal separation, and induced apoptosis in the CRC cells; however, NDs did not induce these effects. Conjugation of ND-PTX with Cet (ND-PTX-Cet) was specifically binding to the EGFR-positive CRC cells and enhanced the mitotic catastrophe and apoptosis induction. Besides, ND-PTX-Cet markedly decreased tumor size in the xenograft EGFR-expressed human CRC tumors of nude mice. Moreover, ND-PTX-Cet induced the mitotic marker protein phospho-histone 3 (Ser10) and apoptotic protein active-caspase 3 for mitotic catastrophe and apoptosis. Taken together, this study demonstrated that the co-delivery of PTX and Cet by ND enhanced the effects of mitotic catastrophe and apoptosis in vitro and in vivo, which may be applied in the human CRC therapy.

  12. Thyroid Functions and Bipolar Affective Disorder

    Directory of Open Access Journals (Sweden)

    Subho Chakrabarti

    2011-01-01

    Full Text Available Accumulating evidence suggests that hypothalamo-pituitary-thyroid (HPT axis dysfunction is relevant to the pathophysiology and clinical course of bipolar affective disorder. Hypothyroidism, either overt or more commonly subclinical, appears to the commonest abnormality found in bipolar disorder. The prevalence of thyroid dysfunction is also likely to be greater among patients with rapid cycling and other refractory forms of the disorder. Lithium-treatment has potent antithyroid effects and can induce hypothyroidism or exacerbate a preexisting hypothyroid state. Even minor perturbations of the HPT axis may affect the outcome of bipolar disorder, necessitating careful monitoring of thyroid functions of patients on treatment. Supplementation with high dose thyroxine can be considered in some patients with treatment-refractory bipolar disorder. Neurotransmitter, neuroimaging, and genetic studies have begun to provide clues, which could lead to an improved understanding of the thyroid-bipolar disorder connection, and more optimal ways of managing this potentially disabling condition.

  13. Diagnostic stability in pediatric bipolar disorder

    DEFF Research Database (Denmark)

    Vedel Kessing, Lars; Vradi, Eleni; Andersen, Per Kragh

    2015-01-01

    BACKGROUND: The diagnostic stability of pediatric bipolar disorder has not been investigated previously. The aim was to investigate the diagnostic stability of the ICD-10 diagnosis of pediatric mania/bipolar disorder.METHODS: All patients below 19 years of age who got a diagnosis of mania/bipolar...... disorder at least once in a period from 1994 to 2012 at psychiatric inpatient or outpatient contact in Denmark were identified in a nationwide register.RESULTS: Totally, 354 children and adolescents got a diagnosis of mania/bipolar disorder at least once; a minority, 144 patients (40.7%) got the diagnosis...... at the first contact whereas the remaining patients (210; 59.3%) got the diagnosis at later contacts before age 19. For the latter patients, the median time elapsed from first treatment contact with the psychiatric service system to the first diagnosis with a manic episode/bipolar disorder was nearly 1 year...

  14. 2017 Bipolar Plate Workshop Summary Report

    Energy Technology Data Exchange (ETDEWEB)

    Kopasz, John P. [Argonne National Lab. (ANL), Argonne, IL (United States); Benjamin, Thomas G. [Argonne National Lab. (ANL), Argonne, IL (United States); Schenck, Deanna [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-08-17

    The Bipolar Plate (BP) Workshop was held at USCAR1 in Southfield, Michigan on February 14, 2017 and included 63 participants from industry, government agencies, universities, and national laboratories with expertise in the relevant fields. The objective of the workshop was to identify research and development (R&D) needs, in particular early-stage R&D, for bipolar plates for polymer electrolyte membrane (PEM) fuel cells for transportation applications. The focus of the workshop was on materials, manufacturing, and design aspects of bipolar plates with the goal of meeting DOE’s 2020 bipolar plate targets. Of special interest was the cost target of ≤$3/kW for the bipolar plate.

  15. White Matter Structure in Older Adults Moderates the Benefit of Sleep Spindles on Motor Memory Consolidation.

    Science.gov (United States)

    Mander, Bryce A; Zhu, Alyssa H; Lindquist, John R; Villeneuve, Sylvia; Rao, Vikram; Lu, Brandon; Saletin, Jared M; Ancoli-Israel, Sonia; Jagust, William J; Walker, Matthew P

    2017-11-29

    Sleep spindles promote the consolidation of motor skill memory in young adults. Older adults, however, exhibit impoverished sleep-dependent motor memory consolidation. The underlying pathophysiological mechanism(s) explaining why motor memory consolidation in older adults fails to benefit from sleep remains unclear. Here, we demonstrate that male and female older adults show impoverished overnight motor skill memory consolidation relative to young adults, with the extent of impairment being associated with the degree of reduced frontal fast sleep spindle density. The magnitude of the loss of frontal fast sleep spindles in older adults was predicted by the degree of reduced white matter integrity throughout multiple white matter tracts known to connect subcortical and cortical brain regions. We further demonstrate that the structural integrity of selective white matter fiber tracts, specifically within right posterior corona radiata, right tapetum, and bilateral corpus callosum, statistically moderates whether sleep spindles promoted overnight consolidation of motor skill memory. Therefore, white matter integrity within tracts known to connect cortical sensorimotor control regions dictates the functional influence of sleep spindles on motor skill memory consolidation in the elderly. The deterioration of white matter fiber tracts associated with human brain aging thus appears to be one pathophysiological mechanism influencing subcortical-cortical propagation of sleep spindles and their related memory benefits. SIGNIFICANCE STATEMENT Numerous studies have shown that sleep spindle expression is reduced and sleep-dependent motor memory is impaired in older adults. However, the mechanisms underlying these alterations have remained unknown. The present study reveals that age-related degeneration of white matter within select fiber tracts is associated with reduced sleep spindles in older adults. We further demonstrate that, within these same fiber tracts, the degree of

  16. Nanofluidic diode and bipolar transistor.

    Science.gov (United States)

    Daiguji, Hirofumi; Oka, Yukiko; Shirono, Katsuhiro

    2005-11-01

    Theoretical modeling of ionic distribution and transport in a nanochannel containing a surface charge on its wall, 30 nm high and 5 microm long, suggests that ionic current can be controlled by locally modifying the surface charge density through a gate electrode, even if the electrical double layers are not overlapped. When the surface charge densities at the right and left halves of a channel are the same absolute value but of different signs, this could form the basis of a nanofluidic diode. When the surface charge density at the middle part of a channel is modified, this could form the basis of a nanofluidic bipolar transistor.

  17. Frequency and mitotic heritability of epimutations in Schistosoma mansoni.

    Science.gov (United States)

    Roquis, David; Rognon, Anne; Chaparro, Cristian; Boissier, Jerome; Arancibia, Nathalie; Cosseau, Celine; Parrinello, Hugues; Grunau, Christoph

    2016-04-01

    Schistosoma mansoni is a parasitic platyhelminth responsible for intestinal bilharzia. It has a complex life cycle, infecting a freshwater snail of the Biomphalaria genus, and then a mammalian host. Schistosoma mansoni adapts rapidly to new (allopatric) strains of its intermediate host. To study the importance of epimutations in this process, we infected sympatric and allopatric mollusc strains with parasite clones. ChIP-Seq was carried out on four histone modifications (H3K4me3, H3K27me3, H3K27ac and H4K20me1) in parallel with genomewide DNA resequencing (i) on parasite larvae shed by the infected snails and (ii) on adult worms that had developed from the larvae. No change in single nucleotide polymorphisms and no mobilization of transposable elements were observed, but 58-105 copy number variations (CNVs) within the parasite clones in different molluscs were detected. We also observed that the allopatric environment induces three types of chromatin structure changes: (i) host-induced changes on larvae epigenomes in 51 regions of the genome that are independent of the parasites' genetic background, (ii) spontaneous changes (not related to experimental condition or genotype of the parasite) at 64 locations and (iii) 64 chromatin structure differences dependent on the parasite genotype. Up to 45% of the spontaneous, but none of the host-induced chromatin structure changes were transmitted to adults. In our model, the environment induces epigenetic changes at specific loci but only spontaneous epimutations are mitotically heritable and have therefore the potential to contribute to transgenerational inheritance. We also show that CNVs are the only source of genetic variation and occur at the same order of magnitude as epimutations. © 2016 John Wiley & Sons Ltd.

  18. Mitotic motors coregulate microtubule patterns in axons and dendrites.

    Science.gov (United States)

    Lin, Shen; Liu, Mei; Mozgova, Olga I; Yu, Wenqian; Baas, Peter W

    2012-10-03

    Microtubules are nearly uniformly oriented in the axons of vertebrate neurons but are non-uniformly orien