Sample records for cell polarity keeping

  1. Cell Polarity Signaling in Arabidopsis


    Yang, Zhenbiao


    Cell polarization is intimately linked to plant development, growth, and responses to the environment. Major advances have been made in our understanding of the signaling pathways and networks that regulate cell polarity in plants owing to recent studies on several model systems, e.g., tip growth in pollen tubes, cell morphogenesis in the leaf epidermis, and polar localization of PINs. From these studies we have learned that plant cells use conserved mechanisms such as Rho family GTPases to i...

  2. Integrins and epithelial cell polarity. (United States)

    Lee, Jessica L; Streuli, Charles H


    Cell polarity is characterised by differences in structure, composition and function between at least two poles of a cell. In epithelial cells, these spatial differences allow for the formation of defined apical and basal membranes. It has been increasingly recognised that cell-matrix interactions and integrins play an essential role in creating epithelial cell polarity, although key gaps in our knowledge remain. This Commentary will discuss the mounting evidence for the role of integrins in polarising epithelial cells. We build a model in which both inside-out signals to polarise basement membrane assembly at the basal surface, and outside-in signals to control microtubule apical-basal orientation and vesicular trafficking are required for establishing and maintaining the orientation of epithelial cell polarity. Finally, we discuss the relevance of the basal integrin polarity axis to cancer. This article is part of a Minifocus on Establishing polarity.

  3. Cell polarity proteins and spermatogenesis. (United States)

    Gao, Ying; Xiao, Xiang; Lui, Wing-Yee; Lee, Will M; Mruk, Dolores; Cheng, C Yan


    When the cross-section of a seminiferous tubule from an adult rat testes is examined microscopically, Sertoli cells and germ cells in the seminiferous epithelium are notably polarized cells. For instance, Sertoli cell nuclei are found near the basement membrane. On the other hand, tight junction (TJ), basal ectoplasmic specialization (basal ES, a testis-specific actin-rich anchoring junction), gap junction (GJ) and desmosome that constitute the blood-testis barrier (BTB) are also located near the basement membrane. The BTB, in turn, divides the epithelium into the basal and the adluminal (apical) compartments. Within the epithelium, undifferentiated spermatogonia and preleptotene spermatocytes restrictively reside in the basal compartment whereas spermatocytes and post-meiotic spermatids reside in the adluminal compartment. Furthermore, the heads of elongating/elongated spermatids point toward the basement membrane with their elongating tails toward the tubule lumen. However, the involvement of polarity proteins in this unique cellular organization, in particular the underlying molecular mechanism(s) by which polarity proteins confer cellular polarity in the seminiferous epithelium is virtually unknown until recent years. Herein, we discuss latest findings regarding the role of different polarity protein complexes or modules and how these protein complexes are working in concert to modulate Sertoli cell and spermatid polarity. These findings also illustrate polarity proteins exert their effects through the actin-based cytoskeleton mediated by actin binding and regulatory proteins, which in turn modulate adhesion protein complexes at the cell-cell interface since TJ, basal ES and GJ utilize F-actin for attachment. We also propose a hypothetical model which illustrates the antagonistic effects of these polarity proteins. This in turn provides a unique mechanism to modulate junction remodeling in the testis to support germ cell transport across the epithelium in

  4. A Novel Keep Zero as Zero Polar Correlation Technique for Mobile Robot Localization using LIDAR

    Directory of Open Access Journals (Sweden)



    Full Text Available Sensor fusion based localization techniques often need accurate estimate of the fast and uncertain scene change in environment. To determine the scene change from two consecutive LIDAR scans, this paper proposes a novel technique called 'keep zero as zero' polar correlation. As it name implies any zero in the scan data is kept isolated from scene change estimation as it do not carry any information about scene change. Unlike existing techniques, the proposed methodology employs minimization of selective horizontal and vertically shifted sum of difference between the scans to estimate scene change in terms of rotation and translation. Minimization of the proposed correlation function across the specified search space can guarantee an accurate estimate of scene change without any ambiguity. The performance of the proposed method is tested experimentally on a mobile robot in two modes depending on the scene change. In the first mode, scene change is detected using dynamic LIDAR, whereas static LIDAR is used in the second mode. The proposed methodology is found to be more robust to environmental uncertainties with a reliable level of localization accuracy.

  5. Planar cell polarity signaling: a common mechanism for cellular polarization. (United States)

    Jenny, Andreas; Mlodzik, Marek


    Epithelial cells frequently display--in addition to the common apical-basolateral polarity--a polarization within the plane of the epithelium. This is commonly referred to as planar cell polarity (PCP) or tissue polarity. Examples of vertebrate PCP include epithelial patterning in the skin and inner ear, and also the morphogenetic movements of mesenchymal cells during convergent extension at gastrulation. In Drosophila, all adult epithelial structures of the cuticle are polarized within the plane. This review presents recent results and new insights into the molecular mechanisms underlying the establishment of PCP, and compares and contrasts the intriguing similarities between PCP signaling in Drosophila and vertebrates.

  6. Normalized polarization ratios for the analysis of cell polarity.

    Directory of Open Access Journals (Sweden)

    Raz Shimoni

    Full Text Available The quantification and analysis of molecular localization in living cells is increasingly important for elucidating biological pathways, and new methods are rapidly emerging. The quantification of cell polarity has generated much interest recently, and ratiometric analysis of fluorescence microscopy images provides one means to quantify cell polarity. However, detection of fluorescence, and the ratiometric measurement, is likely to be sensitive to acquisition settings and image processing parameters. Using imaging of EGFP-expressing cells and computer simulations of variations in fluorescence ratios, we characterized the dependence of ratiometric measurements on processing parameters. This analysis showed that image settings alter polarization measurements; and that clustered localization is more susceptible to artifacts than homogeneous localization. To correct for such inconsistencies, we developed and validated a method for choosing the most appropriate analysis settings, and for incorporating internal controls to ensure fidelity of polarity measurements. This approach is applicable to testing polarity in all cells where the axis of polarity is known.

  7. Insight into planar cell polarity. (United States)

    Sebbagh, Michael; Borg, Jean-Paul


    Planar cell polarity or PCP refers to a uniform cellular organization within the plan, typically orthogonal to the apico-basal polarity axis. As such, PCP provides directional cues that control and coordinate the integration of cells in tissues to build a living organism. Although dysfunctions of this fundamental cellular process have been convincingly linked to the etiology of various pathologies such as cancer and developmental defects, the molecular mechanisms governing its establishment and maintenance remain poorly understood. Here, we review some aspects of invertebrate and vertebrate PCPs, highlighting similarities and differences, and discuss the prevalence of the non-canonical Wnt signaling as a central PCP pathway, as well as recent findings on the importance of cell contractility and cilia as promising avenues of investigation.

  8. Planar Cell Polarity: A Bridge Too Far?



    Summary The mechanisms of planar cell polarity are being revealed by genetic analysis. Recent studies have provided new insights into interactions between three proteins involved in planar cell polarity: Flamingo, Frizzled and Van Gogh.

  9. In the darkness of the polar night, scallops keep on a steady rhythm (United States)

    Tran, Damien; Sow, Mohamedou; Camus, Lionel; Ciret, Pierre; Berge, Jorgen; Massabuau, Jean-Charles


    Although the prevailing paradigm has held that the polar night is a period of biological quiescence, recent studies have detected noticeable activity levels in marine organisms. In this study, we investigated the circadian rhythm of the scallop Chlamys islandica by continuously recording the animal’s behaviour over 3 years in the Arctic (Svalbard). Our results showed that a circadian rhythm persists throughout the polar night and lasts for at least 4 months. Based on observations across three polar nights, we showed that the robustness and synchronicity of the rhythm depends on the angle of the sun below the horizon. The weakest rhythm occurred at the onset of the polar night during the nautical twilight. Surprisingly, the circadian behaviour began to recover during the darkest part of the polar night. Because active rhythms optimize the fitness of an organism, our study brings out that the scallops C. islandica remain active even during the polar night.

  10. Wnt-Dependent Control of Cell Polarity in Cultured Cells. (United States)

    Runkle, Kristin B; Witze, Eric S


    The secreted ligand Wnt5a regulates cell polarity and polarized cell movement during development by signaling through the poorly defined noncanonical Wnt pathway. Cell polarity regulates most aspects of cell behavior including the organization of apical/basolateral membrane domains of epithelial cells, polarized cell divisions along a directional plane, and front rear polarity during cell migration. These characteristics of cell polarity allow coordinated cell movements required for tissue formation and organogenesis during embryonic development. Genetic model organisms have been used to identify multiple signaling pathways including Wnt5a that are required to establish cell polarity and regulate polarized cell behavior. However, the downstream signaling events that regulate these complex cellular processes are still poorly understood. The methods below describe assays to study Wnt5a-induced cell polarity in cultured cells, which may facilitate our understanding of these complex signaling pathways.

  11. Translating cell polarity into tissue elongation



    Planar cell polarity, the orientation of single-cell asymmetries within the plane of a multicellular tissue, is essential to generating the shape and dimensions of organs and organisms. Planar polarity systems align cell behavior with the body axes and orient the cellular processes that lead to tissue elongation. Using Drosophila as a model system, significant progress has been made toward understanding how planar polarity is generated by biochemical and mechanical signals. Recent studies usi...

  12. Coronavirus infection of polarized epithelial cells

    NARCIS (Netherlands)

    Rossen, J W; Horzinek, M C; Rottier, P J


    Epithelial cells are the first host cells to be infected by incoming c oronaviruses. Recent observations in vitro show that coronaviruses are released from a specific side of these polarized cells, and this polarized release might be important for the spread of the infection in vivo. Mechanisms for

  13. Coupling planar cell polarity signaling to morphogenesis. (United States)

    Axelrod, Jeffrey D; McNeill, Helen


    Epithelial cells and other groups of cells acquire a polarity orthogonal to their apical-basal axes, referred to as Planar Cell Polarity (PCP). The process by which these cells become polarized requires a signaling pathway using Frizzled as a receptor. Responding cells sense cues from their environment that provide directional information, and they translate this information into cellular asymmetry. Most of what is known about PCP derives from studies in the fruit fly, Drosophila. We review what is known about how cells translate an unknown signal into asymmetric cytoskeletal reorganization. We then discuss how the vertebrate processes of convergent extension and cochlear hair-cell development may relate to Drosophila PCP signaling.

  14. Planar cell polarity and vertebrate organogenesis. (United States)

    Karner, Courtney; Wharton, Keith A; Carroll, Thomas J


    In addition to being polarized along their apical/basal axis, cells composing most (if not all) organs are also polarized in a plane vertical to the A/B axis. Recent studies indicate that this so-called planar cell polarity (PCP) plays an essential role in the formation of multiple organ systems regulating directed cell migrations, polarized cell division and proper differentiation. In this review we will discuss the molecular mechanisms regulating PCP, including the hypothesized roles for Wnt ligands in this process, and its roles in vertebrate organogenesis.

  15. Planar Cell Polarity Pathway – Coordinating morphogenetic cell behaviors with embryonic polarity



    Planar cell polarization entails establishment of cellular asymmetries within the tissue plane. An evolutionarily conserved Planar Cell Polarity (PCP) signaling system employs intra- and intercellular feedback interactions between its core components, including Frizzled, Van Gogh, Flamingo, Prickle and Dishevelled, to establish their characteristic asymmetric intracellular distributions and coordinate planar polarity of cell populations. By translating global patterning information into asymm...

  16. Modelling planar cell polarity in Drosophila melanogaster



    During development, polarity is a common feature of many cell types. One example is the polarisation of whole fields of epithelial cells within the plane of the epithelium, a phenomenon called planar cell polarity (PCP). It is widespread in nature and plays important roles in development and physiology. Prominent examples include the epithelial cells of external structures of insects like the fruit fly Drosophila melanogaster, polarised tissue morphogenesis in vertebrates and sensory hair cel...

  17. Planar cell polarity of the kidney. (United States)

    Schnell, Ulrike; Carroll, Thomas J


    Planar cell polarity (PCP) or tissue polarity refers to the polarization of tissues perpendicular to the apical-basal axis. Most epithelia, including the vertebrate kidney, show signs of planar polarity. In the kidney, defects in planar polarity are attributed to several disease states including multiple forms of cystic kidney disease. Indeed, planar cell polarity has been shown to be essential for several cellular processes that appear to be necessary for establishing and maintaining tubule diameter. However, uncovering the genetic mechanisms underlying PCP in the kidney has been complicated as the roles of many of the main players are not conserved in flies and vice versa. Here, we review a number of cellular and molecular processes that can affect PCP of the kidney with a particular emphasis on the mechanisms that do not appear to be conserved in flies or that are not part of canonical determinants.

  18. Cell Polarity Proteins in Breast Cancer Progression. (United States)

    Rejon, Carlis; Al-Masri, Maia; McCaffrey, Luke


    Breast cancer, one of the leading causes of cancer related death in women worldwide, is a heterogeneous disease with diverse subtypes that have different properties and prognoses. The developing mammary gland is a highly proliferative and invasive tissue, and some of the developmental programs may be aberrantly activated to promote breast cancer progression. In the breast, luminal epithelial cells exhibit apical-basal polarity, and the failure to maintain this organizational structure, due to disruption of polarity complexes, is implicated in promoting hyperplasia and tumors. Therefore, understanding the mechanisms underlying loss of polarity will contribute to our knowledge of the early stages leading to the pathogenesis of the disease. In this review, we will discuss recent findings that support the idea that loss of apical-basal cell polarity is a crucial step in the acquisition of the malignant phenotype. Oncogene induced loss of tissue organization shares a conserved cellular mechanism with developmental process, we will further describe the role of the individual polarity complexes, the Par, Crumbs, and Scribble, to couple cell division orientation and cell growth. We will examine symmetric or asymmetric cell divisions in mammary stem cell and their contribution to the development of breast cancer subtypes and cancer stem cells. Finally, we will highlight some of the recent advances in our understanding of the molecular mechanisms by which changes in epithelial polarity programs promote invasion and metastasis through single cell and collective cell modes. J. Cell. Biochem. 117: 2215-2223, 2016. © 2016 Wiley Periodicals, Inc.

  19. Planar cell polarity: one or two pathways? (United States)

    Lawrence, Peter A; Struhl, Gary; Casal, José


    In multicellular organisms, cells are polarized in the plane of the epithelial sheet, revealed in some cell types by oriented hairs or cilia. Many of the underlying genes have been identified in Drosophila melanogaster and are conserved in vertebrates. Here we dissect the logic of planar cell polarity (PCP). We review studies of genetic mosaics in adult flies - marked cells of different genotypes help us to understand how polarizing information is generated and how it passes from one cell to another. We argue that the prevailing opinion that planar polarity depends on a single genetic pathway is wrong and conclude that there are (at least) two independently acting processes. This conclusion has major consequences for the PCP field.

  20. Cell polarity signaling in the plasticity of cancer cell invasiveness. (United States)

    Gandalovičová, Aneta; Vomastek, Tomáš; Rosel, Daniel; Brábek, Jan


    Apico-basal polarity is typical of cells present in differentiated epithelium while front-rear polarity develops in motile cells. In cancer development, the transition from epithelial to migratory polarity may be seen as the hallmark of cancer progression to an invasive and metastatic disease. Despite the morphological and functional dissimilarity, both epithelial and migratory polarity are controlled by a common set of polarity complexes Par, Scribble and Crumbs, phosphoinositides, and small Rho GTPases Rac, Rho and Cdc42. In epithelial tissues, their mutual interplay ensures apico-basal and planar cell polarity. Accordingly, altered functions of these polarity determinants lead to disrupted cell-cell adhesions, cytoskeleton rearrangements and overall loss of epithelial homeostasis. Polarity proteins are further engaged in diverse interactions that promote the establishment of front-rear polarity, and they help cancer cells to adopt different invasion modes. Invading cancer cells can employ either the collective, mesenchymal or amoeboid invasion modes or actively switch between them and gain intermediate phenotypes. Elucidation of the role of polarity proteins during these invasion modes and the associated transitions is a necessary step towards understanding the complex problem of metastasis. In this review we summarize the current knowledge of the role of cell polarity signaling in the plasticity of cancer cell invasiveness.

  1. Coupling Planar Cell Polarity Signaling to Morphogenesis

    Directory of Open Access Journals (Sweden)

    Jeffrey D. Axelrod


    Full Text Available Epithelial cells and other groups of cells acquire a polarity orthogonal to their apical–basal axes, referred to as Planar Cell Polarity (PCP. The process by which these cells become polarized requires a signaling pathway using Frizzled as a receptor. Responding cells sense cues from their environment that provide directional information, and they translate this information into cellular asymmetry. Most of what is known about PCP derives from studies in the fruit fly, Drosophila. We review what is known about how cells translate an unknown signal into asymmetric cytoskeletal reorganization. We then discuss how the vertebrate processes of convergent extension and cochlear hair-cell development may relate to Drosophila PCP signaling.

  2. Analyzing planar cell polarity during zebrafish gastrulation. (United States)

    Jessen, Jason R


    Planar cell polarity was first described in invertebrates over 20 years ago and is defined as the polarity of cells (and cell structures) within the plane of a tissue, such as an epithelium. Studies in the last 10 years have identified critical roles for vertebrate homologs of these planar cell polarity proteins during gastrulation cell movements. In zebrafish, the terms convergence and extension are used to describe the collection of morphogenetic movements and cell behaviors that contribute to narrowing and elongation of the embryonic body plan. Disruption of planar cell polarity gene function causes profound defects in convergence and extension creating an embryo that has a shortened anterior-posterior axis and is broadened mediolaterally. The zebrafish gastrula-stage embryo is transparent and amenable to live imaging using both Nomarski/differential interference contrast and fluorescence microscopy. This chapter describes methods to analyze convergence and extension movements at the cellular level and thereby connect embryonic phenotypes with underlying planar cell polarity defects in migrating cells.

  3. Fidelity in planar cell polarity signalling. (United States)

    Ma, Dali; Yang, Chung-hui; McNeill, Helen; Simon, Michael A; Axelrod, Jeffrey D


    The polarity of Drosophila wing hairs displays remarkable fidelity. Each of the approximately 30,000 wing epithelial cells constructs an actin-rich prehair that protrudes from its distal vertex and points distally. The distal location and orientation of the hairs is virtually error free, thus forming a nearly perfect parallel array. This process is controlled by the planar cell polarity signalling pathway. Here we show that interaction between two tiers of the planar cell polarity signalling mechanism results in the observed high fidelity. The first tier, mediated by the cadherin Fat, dictates global orientation by transducing a directional signal to individual cells. The second tier, orchestrated by the 7-pass transmembrane receptor Frizzled, aligns each cell's polarity with that of its neighbours through the action of an intercellular feedback loop, enabling polarity to propagate from cell to cell. We show that all cells need not respond correctly to the presumably subtle signal transmitted by Fat. Subsequent action of the Frizzled feedback loop is sufficient to align all the cells cooperatively. This economical system is therefore highly robust, and produces virtually error-free arrays.

  4. Polarized sorting and trafficking in epithelial cells

    Institute of Scientific and Technical Information of China (English)

    Xinwang Cao; Michal A Surma; Kai Simons


    The polarized distribution of proteins and lipids at the surface membrane of epithelial cells results in the formation of an apical and a basolateral domain,which are separated by tight junctions.The generation and maintenance of epithelial polarity require elaborate mechanisms that guarantee correct sorting and vectorial delivery of cargo molecules.This dynamic process involves the interaction of sorting signals with sorting machineries and the formation of transport carriers.Here we review the recent advances in the field of polarized sorting in epithelial cells.We especially highlight the role of lipid rafts in apical sorting.

  5. Does cell polarity matter during spermatogenesis? (United States)

    Gao, Ying; Cheng, C Yan


    Cell polarity is crucial to development since apico-basal polarity conferred by the 3 polarity protein modules (or complexes) is essential during embryogenesis, namely the Par (partition defective)-, the CRB (Crumbs)-, and the Scribble-based polarity protein modules. While these protein complexes and their component proteins have been extensively studied in Drosophila and C. elegans and also other mammalian tissues and/or cells, their presence and physiological significance in the testis remain unexplored until the first paper on the Par-based protein published in 2008. Since then, the Par-, the Scribble- and the CRB-based protein complexes and their component proteins in the testis have been studied. These proteins are known to confer Sertoli and spermatid polarity in the seminiferous epithelium, and they are also integrated components of the tight junction (TJ) and the basal ectoplasmic specialization (ES) at the Sertoli cell-cell interface near the basement membrane, which in turn constitute the blood-testis barrier (BTB). These proteins are also found at the apical ES at the Sertoli-spermatid interface. Thus, these polarity proteins also play a significant role in regulating Sertoli and spermatid adhesion in the testis through their actions on actin-based cytoskeletal function. Recent studies have shown that these polarity proteins are having antagonistic effects on the BTB integrity in which the Par6- and CRB3-based polarity complexes promotes the integrity of the Sertoli cell TJ-permeability barrier, whereas the Scribble-based complex promotes restructuring/remodeling of the Sertoli TJ-barrier function. Herein, we carefully evaluate these findings and provide a hypothetic model regarding their role in the testis in the context of the functions of these polarity proteins in other epithelia, so that better experiments can be designed in future studies to explore their significance in spermatogenesis.

  6. T cell polarizing properties of probiotic bacteria. (United States)

    Barberi, Chiara; Campana, Stefania; De Pasquale, Claudia; Rabbani Khorasgani, Mohammad; Ferlazzo, Guido; Bonaccorsi, Irene


    Different commensal bacteria employed as probiotics have been shown to be endowed with immunomodulatory properties and to actively interact with antigen presenting cells, such as dendritic cells and macrophages. In particular, different strains of probiotic bacteria may induce the secretion of a discrete cytokine profile able to induce divergent T cell polarization. Here, we briefly review current knowledge regarding the effects of different species and strains of probiotic bacteria on T cell polarization. Given that the loss of intestinal homeostasis is frequently associated with an aberrant T cell polarization profile, a comprehensive knowledge of the immunomodulatory potential of these bacteria is crucial for their employment in the management of human immune-mediated pathologies, such as allergies or inflammatory bowel diseases.

  7. Polarized Cell Division of Chlamydia trachomatis. (United States)

    Abdelrahman, Yasser; Ouellette, Scot P; Belland, Robert J; Cox, John V


    Bacterial cell division predominantly occurs by a highly conserved process, termed binary fission, that requires the bacterial homologue of tubulin, FtsZ. Other mechanisms of bacterial cell division that are independent of FtsZ are rare. Although the obligate intracellular human pathogen Chlamydia trachomatis, the leading bacterial cause of sexually transmitted infections and trachoma, lacks FtsZ, it has been assumed to divide by binary fission. We show here that Chlamydia divides by a polarized cell division process similar to the budding process of a subset of the Planctomycetes that also lack FtsZ. Prior to cell division, the major outer-membrane protein of Chlamydia is restricted to one pole of the cell, and the nascent daughter cell emerges from this pole by an asymmetric expansion of the membrane. Components of the chlamydial cell division machinery accumulate at the site of polar growth prior to the initiation of asymmetric membrane expansion and inhibitors that disrupt the polarity of C. trachomatis prevent cell division. The polarized cell division of C. trachomatis is the result of the unipolar growth and FtsZ-independent fission of this coccoid organism. This mechanism of cell division has not been documented in other human bacterial pathogens suggesting the potential for developing Chlamydia-specific therapeutic treatments.

  8. Spatial stochastic dynamics enable robust cell polarization.

    Directory of Open Access Journals (Sweden)

    Michael J Lawson

    Full Text Available Although cell polarity is an essential feature of living cells, it is far from being well-understood. Using a combination of computational modeling and biological experiments we closely examine an important prototype of cell polarity: the pheromone-induced formation of the yeast polarisome. Focusing on the role of noise and spatial heterogeneity, we develop and investigate two mechanistic spatial models of polarisome formation, one deterministic and the other stochastic, and compare the contrasting predictions of these two models against experimental phenotypes of wild-type and mutant cells. We find that the stochastic model can more robustly reproduce two fundamental characteristics observed in wild-type cells: a highly polarized phenotype via a mechanism that we refer to as spatial stochastic amplification, and the ability of the polarisome to track a moving pheromone input. Moreover, we find that only the stochastic model can simultaneously reproduce these characteristics of the wild-type phenotype and the multi-polarisome phenotype of a deletion mutant of the scaffolding protein Spa2. Significantly, our analysis also demonstrates that higher levels of stochastic noise results in increased robustness of polarization to parameter variation. Furthermore, our work suggests a novel role for a polarisome protein in the stabilization of actin cables. These findings elucidate the intricate role of spatial stochastic effects in cell polarity, giving support to a cellular model where noise and spatial heterogeneity combine to achieve robust biological function.

  9. Planar cell polarity signaling in vertebrates. (United States)

    Jones, Chonnettia; Chen, Ping


    Planar cell polarity (PCP) refers to the polarization of a field of cells within the plane of a cell sheet. This form of polarization is required for diverse cellular processes in vertebrates, including convergent extension (CE), the establishment of PCP in epithelial tissues and ciliogenesis. Perhaps the most distinct example of vertebrate PCP is the uniform orientation of stereociliary bundles at the apices of sensory hair cells in the mammalian auditory sensory organ. The establishment of PCP in the mammalian cochlea occurs concurrently with CE in this ciliated epithelium, therefore linking three cellular processes regulated by the vertebrate PCP pathway in the same tissue and emerging as a model system for dissecting PCP signaling. This review summarizes the morphogenesis of this model system to assist the interpretation of the emerging data and proposes molecular mechanisms underlying PCP signaling in vertebrates.

  10. Coronaviruses in polarized epithelial cells

    NARCIS (Netherlands)

    Rossen, J W; Bekker, C P; Voorhout, W F; Horzinek, M C; Van der Ende, A; Strous, G J; Rottier, P J


    Coronaviruses have a marked tropism for epithelial cells. In this paper the interactions of the porcine transmissible gastroenteritis virus (TGEV) and mouse hepatitis virus (MHV-A59) with epithelial cells are compared. Porcine (LLC-PK1) and murine (mTAL) epithelial cells were grown on permeable supp

  11. Development and dynamics of cell polarity at a glance. (United States)

    Campanale, Joseph P; Sun, Thomas Y; Montell, Denise J


    Cells exhibit morphological and molecular asymmetries that are broadly categorized as cell polarity. The cell polarity established in early embryos prefigures the macroscopic anatomical asymmetries characteristic of adult animals. For example, eggs and early embryos have polarized distributions of RNAs and proteins that generate global anterior/posterior and dorsal/ventral axes. The molecular programs that polarize embryos are subsequently reused in multiple contexts. Epithelial cells require apical/basal polarity to establish their barrier function. Migrating cells polarize in the direction of movement, creating distinct leading and trailing structures. Asymmetrically dividing stem cells partition different molecules between themselves and their daughter cells. Cell polarity can develop de novo, be maintained through rounds of cell division and be dynamically remodeled. In this Cell Science at a Glance review and poster, we describe molecular asymmetries that underlie cell polarity in several cellular contexts. We highlight multiple developmental systems that first establish cell/developmental polarity, and then maintain it. Our poster showcases repeated use of the Par, Scribble and Crumbs polarity complexes, which drive the development of cell polarity in many cell types and organisms. We then briefly discuss the diverse and dynamic changes in cell polarity that occur during cell migration, asymmetric cell division and in planar polarized tissues.

  12. Observing planar cell polarity in multiciliated mouse airway epithelial cells. (United States)

    Vladar, Eszter K; Lee, Yin Loon; Stearns, Tim; Axelrod, Jeffrey D


    The concerted movement of cilia propels inhaled contaminants out of the lungs, safeguarding the respiratory system from toxins, pathogens, pollutants, and allergens. Motile cilia on the multiciliated cells (MCCs) of the airway epithelium are physically oriented along the tissue axis for directional motility, which depends on the planar cell polarity (PCP) signaling pathway. The MCCs of the mouse respiratory epithelium have emerged as an important model for the study of motile ciliogenesis and the PCP signaling mechanism. Unlike other motile ciliated or planar polarized tissues, airway epithelial cells are relatively easily accessible and primary cultures faithfully model many of the essential features of the in vivo tissue. There is growing interest in understanding how cells acquire and polarize motile cilia due to the impact of mucociliary clearance on respiratory health. Here, we present methods for observing and quantifying the planar polarized orientation of motile cilia both in vivo and in primary culture airway epithelial cells. We describe how to acquire and evaluate electron and light microscopy images of ciliary ultrastructural features that reveal planar polarized orientation. Furthermore, we describe the immunofluorescence localization of PCP pathway components as a simple readout for airway epithelial planar polarization and ciliary orientation. These methods can be adapted to observe ciliary orientation in other multi- and monociliated cells and to detect PCP pathway activity in any tissue or cell type.

  13. GTPases in bacterial cell polarity and signalling. (United States)

    Bulyha, Iryna; Hot, Edina; Huntley, Stuart; Søgaard-Andersen, Lotte


    In bacteria, large G domain GTPases have well-established functions in translation, protein translocation, tRNA modification and ribosome assembly. In addition, bacteria also contain small Ras-like GTPases consisting of stand-alone G domains. Recent data have revealed that small Ras-like GTPases as well as large G domain GTPases in bacteria function in the regulation of cell polarity, signal transduction and possibly also in cell division. The small Ras-like GTPase MglA together with its cognate GAP MglB regulates cell polarity in Myxococcus xanthus, and the small Ras-like GTPase CvnD9 in Streptomyces coelicolor is involved in signal transduction. Similarly, the large GTPase FlhF together with the ATPase FlhG regulates the localization and number of flagella in polarly flagellated bacteria. Moreover, large dynamin-like GTPases in bacteria may function in cell division. Thus, the function of GTPases in bacteria may be as pervasive as in eukaryotes.

  14. Methods for studying planar cell polarity. (United States)

    Olofsson, Jessica; Axelrod, Jeffrey D


    Planar cell polarity (PCP) is the polarity of epithelial cells in the plane orthogonal to the apical-basal axis, and is controlled by a partially defined signaling system. PCP related signaling also plays roles in cell migration, tissue re-organization and stem cell differentiation during embryonic development, and later, in regeneration and repair. Aberrant signaling has been linked to a broad range of pathophysiologies including cancer, developmental defects, and neurological disorders. The deepest mechanistic insights have come from studies of PCP in Drosophila. In this chapter we review tools and methods to study PCP signaling in Drosophila epithelia, where it was found to involve asymmetric protein localization that is coordinated between adjacent cells. Such signaling has been most extensively studied in wing, eye, and abdomen, but also in other tissues such as leg and notum. In the adult fly, PCP is manifested in the coordinated direction of hairs and bristles, as well as the organization of ommatidia in the eye. The polarity of these structures is preceded by asymmetric localization of PCP signaling proteins at the apical junctions of epithelial cells. Based on genetic and molecular criteria, the proteins that govern PCP can be divided into distinct modules, including the core module, the Fat/Dachsous/Four-jointed (Fat/Ds/Fj) module (often referred to as the 'global' module) as well as tissue specific effector modules. Different tissues and tissue regions differ in their sensitivity to disturbances in the various modules of the PCP signaling system, leading to controversies about the interactions among the modules, and emphasizing the value of studying PCP in multiple contexts. Here, we review methods including those generally applicable, as well as some that are selectively useful for analyses of PCP in eye (including eye discs), wing (including wing discs), pupal and adult abdomen, and the cuticle of larvae and embryos.

  15. A gas cell for stopping, storing and polarizing radioactive particles

    CERN Document Server

    Sytema, A; Böll, O; Chernowitz, D; Dijck, E A; Grasdijk, J O; Hoekstra, S; Jungmann, K; Mathavan, S C; Meinema, C; Mohanty, A; Müller, S E; Portela, M Nuñez; Onderwater, C J G; Pijpker, C; Willmann, L; Wilschut, H W


    A radioactive beam of 20Na is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenological model.

  16. A gas cell for stopping, storing and polarizing radioactive particles

    NARCIS (Netherlands)

    Sytema, Auke; van den Berg, Joost; Böll, Oliver; Chernowitz, Daniel; Dijck, Elwin; Grasdijk, Jan; Hoekstra, Steven; Jungmann, Klaus-Peter; Chirayath Mathavan, Sreekanth; Meinema, Jacoba Roelien; Mueller, Stefan E.; Portela, M. N.; Onderwater, Cornelis; Pijpker, Coen; Willmann, Lorenz; Wilschut, H. W.


    A radioactive beam of Na-20 is stopped in a gas cell filled with Ne gas. The stopped particles are polarized by optical pumping. The degree of polarization that can be achieved is studied. A maximum polarization of 50% was found. The dynamic processes in the cell are described with a phenomenologica

  17. DLG5 in cell polarity maintenance and cancer development. (United States)

    Liu, Jie; Li, Juan; Ren, Yu; Liu, Peijun


    Failure in establishment and maintenance of epithelial cell polarity contributes to tumorigenesis. Loss of expression and function of cell polarity proteins is directly related to epithelial cell polarity maintenance. The polarity protein discs large homolog 5 (DLG5) belongs to a family of molecular scaffolding proteins called Membrane Associated Guanylate Kinases (MAGUKs). As the other family members, DLG5 contains the multi-PDZ, SH3 and GUK domains. DLG5 has evolved in the same manner as DLG1 and ZO1, two well-studied MAGUKs proteins. Just like DLG1 and ZO1, DLG5 plays a role in cell migration, cell adhesion, precursor cell division, cell proliferation, epithelial cell polarity maintenance, and transmission of extracellular signals to the membrane and cytoskeleton. Since the roles of DLG5 in inflammatory bowel disease (IBD) and Crohn's disease (CD) have been reviewed, here, our review focuses on the roles of DLG5 in epithelial cell polarity maintenance and cancer development.

  18. Auxin regulation of cell polarity in plants. (United States)

    Pan, Xue; Chen, Jisheng; Yang, Zhenbiao


    Auxin is well known to control pattern formation and directional growth at the organ/tissue levels via the nuclear TIR1/AFB receptor-mediated transcriptional responses. Recent studies have expanded the arena of auxin actions as a trigger or key regulator of cell polarization and morphogenesis. These actions require non-transcriptional responses such as changes in the cytoskeleton and vesicular trafficking, which are commonly regulated by ROP/Rac GTPase-dependent pathways. These findings beg for the question about the nature of auxin receptors that regulate these responses and renew the interest in ABP1 as a cell surface auxin receptor, including the work showing auxin-binding protein 1 (ABP1) interacts with the extracellular domain of the transmembrane kinase (TMK) receptor-like kinases in an auxin-dependent manner, as well as the debate on this auxin binding protein discovered about 40 years ago. This review highlights recent work on the non-transcriptional auxin signaling mechanisms underscoring cell polarity and shape formation in plants.

  19. Exploring the inhibitory effect of membrane tension on cell polarization. (United States)

    Wang, Weikang; Tao, Kuan; Wang, Jing; Yang, Gen; Ouyang, Qi; Wang, Yugang; Zhang, Lei; Liu, Feng


    Cell polarization toward an attractant is influenced by both physical and chemical factors. Most existing mathematical models are based on reaction-diffusion systems and only focus on the chemical process occurring during cell polarization. However, membrane tension has been shown to act as a long-range inhibitor of cell polarization. Here, we present a cell polarization model incorporating the interplay between Rac GTPase, filamentous actin (F-actin), and cell membrane tension. We further test the predictions of this model by performing single cell measurements of the spontaneous polarization of cancer stem cells (CSCs) and non-stem cancer cells (NSCCs), as the former have lower cell membrane tension. Based on both our model and the experimental results, cell polarization is more sensitive to stimuli under low membrane tension, and high membrane tension improves the robustness and stability of cell polarization such that polarization persists under random perturbations. Furthermore, our simulations are the first to recapitulate the experimental results described by Houk et al., revealing that aspiration (elevation of tension) and release (reduction of tension) result in a decrease in and recovery of the activity of Rac-GTP, respectively, and that the relaxation of tension induces new polarity of the cell body when a cell with the pseudopod-neck-body morphology is severed.

  20. A Gravity-Responsive Time-Keeping Protein of the Plant and Animal Cell Surface (United States)

    Morre, D. James


    The hypothesis under investigation was that a ubiquinol (NADH) oxidase protein of the cell surface with protein disulfide-thiol interchange activity (= NOX protein) is a plant and animal time-keeping ultradian (period of less than 24 h) driver of both cell enlargement and the biological clock that responds to gravity. Despite considerable work in a large number of laboratories spanning several decades, this is, to my knowledge, our work is the first demonstration of a time-keeping biochemical reaction that is both gravity-responsive and growth-related and that has been shown to determine circadian periodicity. As such, the NOX protein may represent both the long-sought biological gravity receptor and the core oscillator of the cellular biological clock. Completed studies have resulted in 12 publications and two issued NASA-owned patents of the clock activity. The gravity response and autoentrainment were characterized in cultured mammalian cells and in two plant systems together with entrainment by light and small molecules (melatonin). The molecular basis of the oscillatory behavior was investigated using spectroscopic methods (Fourier transform infrared and circular dichroism) and high resolution electron microscopy. We have also applied these findings to an understanding of the response to hypergravity. Statistical methods for analysis of time series phenomena were developed (Foster et al., 2003).

  1. Mechanics and polarity in cell motility (United States)

    Ambrosi, D.; Zanzottera, A.


    The motility of a fish keratocyte on a flat substrate exhibits two distinct regimes: the non-migrating and the migrating one. In both configurations the shape is fixed in time and, when the cell is moving, the velocity is constant in magnitude and direction. Transition from a stable configuration to the other one can be produced by a mechanical or chemotactic perturbation. In order to point out the mechanical nature of such a bistable behaviour, we focus on the actin dynamics inside the cell using a minimal mathematical model. While the protein diffusion, recruitment and segregation govern the polarization process, we show that the free actin mass balance, driven by diffusion, and the polymerized actin retrograde flow, regulated by the active stress, are sufficient ingredients to account for the motile bistability. The length and velocity of the cell are predicted on the basis of the parameters of the substrate and of the cell itself. The key physical ingredient of the theory is the exchange among actin phases at the edges of the cell, that plays a central role both in kinematics and in dynamics.

  2. Planar cell polarity in coordinated and directed movements. (United States)

    Tada, Masazumi; Kai, Masatake


    Planar cell polarity is a fundamental concept to understanding the coordination of cell movements in the plane of a tissue. Since the planar cell polarity pathway was discovered in mesenchymal tissues involving cell interaction during vertebrate gastrulation, there is an emerging evidence that a variety of mesenchymal and epithelial cells utilize this genetic pathway to mediate the coordination of cells in directed movements. In this review, we focus on how the planar cell polarity pathway is mediated by migrating cells to communicate with one another in different developmental processes.

  3. Multiscale View of Cytoskeletal Mechanoregulation of Cell and Tissue Polarity. (United States)

    Luxenburg, Chen; Geiger, Benjamin


    The ability of cells to generate, maintain, and repair tissues with complex architecture, in which distinct cells function as coherent units, relies on polarity cues. Polarity can be described as an asymmetry along a defined axis, manifested at the molecular, structural, and functional levels. Several types of cell and tissue polarities were described in the literature, including front-back, apical-basal, anterior-posterior, and left-right polarity. Extensive research provided insights into the specific regulators of each polarization process, as well as into generic elements that affect all types of polarities. The actin cytoskeleton and the associated adhesion structures are major regulators of most, if not all, known forms of polarity. Actin filaments exhibit intrinsic polarity and their ability to bind many proteins including the mechanosensitive adhesion and motor proteins, such as myosins, play key roles in cell polarization. The actin cytoskeleton can generate mechanical forces and together with the associated adhesions, probe the mechanical, structural, and chemical properties of the environment, and transmit signals that impact numerous biological processes, including cell polarity. In this article we highlight novel mechanisms whereby the mechanical forces and actin-adhesion complexes regulate cell and tissue polarity in a variety of natural and experimental systems.

  4. Comparing national home-keeping and the regulation of translational stem cell applications: An international perspective. (United States)

    Sleeboom-Faulkner, Margaret; Chekar, Choon Key; Faulkner, Alex; Heitmeyer, Carolyn; Marouda, Marina; Rosemann, Achim; Chaisinthop, Nattaka; Chang, Hung-Chieh Jessica; Ely, Adrian; Kato, Masae; Patra, Prasanna K; Su, Yeyang; Sui, Suli; Suzuki, Wakana; Zhang, Xinqing


    A very large grey area exists between translational stem cell research and applications that comply with the ideals of randomised control trials and good laboratory and clinical practice and what is often referred to as snake-oil trade. We identify a discrepancy between international research and ethics regulation and the ways in which regulatory instruments in the stem cell field are developed in practice. We examine this discrepancy using the notion of 'national home-keeping', referring to the way governments articulate international standards and regulation with conflicting demands on local players at home. Identifying particular dimensions of regulatory tools - authority, permissions, space and acceleration - as crucial to national home-keeping in Asia, Europe and the USA, we show how local regulation works to enable development of the field, notwithstanding international (i.e. principally 'western') regulation. Triangulating regulation with empirical data and archival research between 2012 and 2015 has helped us to shed light on how countries and organisations adapt and resist internationally dominant regulation through the manipulation of regulatory tools (contingent upon country size, the state's ability to accumulate resources, healthcare demands, established traditions of scientific governance, and economic and scientific ambitions).

  5. Sterol-Rich Membrane Domains Define Fission Yeast Cell Polarity. (United States)

    Makushok, Tatyana; Alves, Paulo; Huisman, Stephen Michiel; Kijowski, Adam Rafal; Brunner, Damian


    Cell polarization is crucial for the functioning of all organisms. The cytoskeleton is central to the process but its role in symmetry breaking is poorly understood. We study cell polarization when fission yeast cells exit starvation. We show that the basis of polarity generation is de novo sterol biosynthesis, cell surface delivery of sterols, and their recruitment to the cell poles. This involves four phases occurring independent of the polarity factor cdc42p. Initially, multiple, randomly distributed sterol-rich membrane (SRM) domains form at the plasma membrane, independent of the cytoskeleton and cell growth. These domains provide platforms on which the growth and polarity machinery assembles. SRM domains are then polarized by the microtubule-dependent polarity factor tea1p, which prepares for monopolar growth initiation and later switching to bipolar growth. SRM polarization requires F-actin but not the F-actin organizing polarity factors for3p and bud6p. We conclude that SRMs are key to cell polarization.

  6. Planar cell polarity planes the inconveniences of cell division into a smooth morphogenetic process. (United States)

    Nechiporuk, Tamilla; Vasioukhin, Valeri


    Cell divisions are necessary, but also very disruptive for morphogenesis. Dividing cells lose many intercellular contacts and polarized features. This breaks the magnificent topology of the developing embryo and, if left unrepaired, can lead to severe tissue disorganization. A recent study demonstrated that cells use the planar cell polarity pathway to reestablish polarity and reintegrate daughter cells into developing tissue.

  7. Planar cell polarity genes regulate polarized extracellular matrix deposition during frog gastrulation. (United States)

    Goto, Toshiyasu; Davidson, Lance; Asashima, Makoto; Keller, Ray


    The noncanonical wnt/planar cell polarity (PCP) pathway [1] regulates the mediolaterally (planarly) polarized cell protrusive activity and intercalation that drives the convergent extension movements of vertebrate gastrulation [2], yet the underlying mechanism is unknown. We report that perturbing expression of Xenopus PCP genes, Strabismus (Xstbm), Frizzled (Xfz7), and Prickle (Xpk), disrupts radially polarized fibronectin fibril assembly on mesodermal tissue surfaces, mediolaterally polarized motility, and intercalation. Polarized motility is restored in Xpk-perturbed explants but not in Xstbm- or Xfz7-perturbed explants cultured on fibronectin surfaces. The PCP complex, including Xpk, first regulates polarized surface assembly of the fibronectin matrix, which is necessary for mediolaterally polarized motility, and then, without Xpk, has an additional and necessary function in polarizing motility. These results show that the PCP complex regulates several cell polarities (radial, planar) and several processes (matrix deposition, motility), by indirect and direct mechanisms, and acts in several modes, either with all or a subset of its components, during vertebrate morphogenesis.

  8. Reciprocal and dynamic polarization of planar cell polarity core components and myosin. (United States)

    Newman-Smith, Erin; Kourakis, Matthew J; Reeves, Wendy; Veeman, Michael; Smith, William C


    The Ciona notochord displays planar cell polarity (PCP), with anterior localization of Prickle (Pk) and Strabismus (Stbm). We report that a myosin is polarized anteriorly in these cells and strongly colocalizes with Stbm. Disruption of the actin/myosin machinery with cytochalasin or blebbistatin disrupts polarization of Pk and Stbm, but not of myosin complexes, suggesting a PCP-independent aspect of myosin localization. Wash out of cytochalasin restored Pk polarization, but not if done in the presence of blebbistatin, suggesting an active role for myosin in core PCP protein localization. On the other hand, in the pk mutant line, aimless, myosin polarization is disrupted in approximately one third of the cells, indicating a reciprocal action of core PCP signaling on myosin localization. Our results indicate a complex relationship between the actomyosin cytoskeleton and core PCP components in which myosin is not simply a downstream target of PCP signaling, but also required for PCP protein localization.

  9. Mechanisms of planar cell polarity establishment in Drosophila. (United States)

    Carvajal-Gonzalez, Jose Maria; Mlodzik, Marek


    Correct patterning and polarization of epithelial and mesenchymal cells are essential for morphogenesis and function of all organs and organisms. Epithelial cells are generally polarized in two axes: (a) the ubiquitous apical-basal axis and (b) polarity within the plane of the epithelium. The latter is generally referred to as planar cell polarity (PCP) and also is found in several contexts of mesenchymal cell patterning. In Drosophila, all adult structures display PCP features, and two conserved molecular systems (the Fat [Ft]/Dachsous [Ds] system and the Frizzled [Fz]/PCP pathway) that regulate this process have been identified. Although significant progress has been made in dissecting aspects of PCP signaling within cells, much remains to be discovered about the mechanisms of long-range and local PCP cell-cell interactions. Here, we discuss the current models based on Drosophila studies and incorporate recent insights into this long-standing cell and developmental biology problem.

  10. Mathematical analysis of spontaneous emergence of cell polarity. (United States)

    Lo, Wing-Cheong; Park, Hay-Oak; Chou, Ching-Shan


    Cell polarization, in which intracellular substances are asymmetrically distributed, enables cells to carry out specialized functions. While cell polarity is often induced by intracellular or extracellular spatial cues, spontaneous polarization (the so-called symmetry breaking) may also occur in the absence of spatial cues. Many computational models have been used to investigate the mechanisms of symmetry breaking, and it was proved that spontaneous polarization occurs when the lateral diffusion of inactive signaling molecules is much faster than that of active signaling molecules. This conclusion leaves an important question of how, as observed in many biological systems, cell polarity emerges when active and inactive membrane-bound molecules diffuse at similar rates while cycling between cytoplasm and membrane takes place. The recent studies of Rätz and Röger showed that, when the cytosolic and membrane diffusion are very different, spontaneous polarization is possible even if the membrane-bound species diffuse at the same rate. In this paper, we formulate a two-equation non-local reaction-diffusion model with general forms of positive feedback. We apply Turing stability analysis to identify parameter conditions for achieving cell polarization. Our results show that spontaneous polarization can be achieved within some parameter ranges even when active and inactive signaling molecules diffuse at similar rates. In addition, different forms of positive feedback are explored to show that a non-local molecule-mediated feedback is important for sharping the localization as well as giving rise to fast dynamics to achieve robust polarization.

  11. Polarized membrane traffic and cell polarity development is dependent on dihydroceramide synthase-regulated sphinganine turnover

    NARCIS (Netherlands)

    van Ijzendoorn, SCD; van der Wouden, JM; Liebisch, G; Schmitz, G; Hoekstra, D


    Sphingoid bases have been implicated in various cellular processes including cell growth, apoptosis and cell differentiation. Here, we show that the regulated turnover of sphingoid bases is crucial for cell polarity development, i.e., the biogenesis of apical plasma membrane domains, in well-differe

  12. The polarized double cell target of the SMC

    CERN Document Server

    Adams, D; Arik, E; Arvidson, A; Badelek, B; Ballintijn, M K; Bardin, G; Baum, G; Berglund, P; Betev, L; Bird, I G; Birsa, R; Björkholm, P; Bonner, B E; De Botton, N R; Boutemeur, M; Bradamante, Franco; Bravar, A; Bressan, A; Bültmann, S; Burtin, E; Cavata, C; Crabb, D; Cranshaw, J; Çuhadar-Dönszelmann, T; Dalla Torre, S; Van Dantzig, R; Derro, B R; Deshpande, A A; Dhawan, S K; Dulya, C M; Dyring, A; Eichblatt, S; Faivre, Jean-Claude; Fasching, D; Feinstein, F; Fernández, C; Forthmann, S; Frois, Bernard; Gallas, A; Garzón, J A; Gaussiran, T; Gilly, H; Giorgi, M A; von Goeler, E; Görtz, S; Gracia, G; De Groot, N; Grosse-Perdekamp, M; Gülmez, E; Haft, K; Von Harrach, D; Hasegawa, T; Hautle, P; Hayashi, N; Heusch, C A; Horikawa, N; Hughes, V W; Igo, G; Ishimoto, S; Iwata, T; Kabuss, E M; Kageya, T; Karev, A G; Kessler, H J; Ketel, T; Kiryluk, J; Kishi, A; Kiselev, Yu F; Klostermann, L; Krämer, Dietrich; Krivokhizhin, V G; Kröger, W; Kurek, K; Kyynäräinen, J; Lamanna, M; Landgraf, U; Layda, T; Le Goff, J M; Lehár, F; de Lesquen, A; Lichtenstadt, J; Lindqvist, T; Litmaath, M; Loewe, M; Magnon, A; Mallot, G K; Marie, F; Martin, A; Martino, J; Matsuda, T; Mayes, B W; McCarthy, J S; Medved, K S; Meyer, W T; Van Middelkoop, G; Miller, D; Miyachi, Y; Mori, K; Moromisato, J H; Nassalski, J P; Naumann, Lutz; Neganov, B S; Niinikoski, T O; Oberski, J; Ogawa, A; Ozben, C; Parks, D P; Pereira, H; Penzo, Aldo L; Perrot-Kunne, F; Peshekhonov, V D; Piegaia, R; Pinsky, L; Platchkov, S K; Pló, M; Pose, D; Postma, H; Pretz, J; Pussieux, T; Pyrlik, J; Rädel, G; Reyhancan, I; Reicherz, G; Rijllart, A; Roberts, J B; Rock, S E; Rodríguez, M; Rondio, Ewa; Rosado, A; Roscherr, B; Sabo, I; Saborido, J; Sandacz, A; Savin, I A; Schiavon, R P; Schiller, A; Schüler, K P; Segel, R E; Seitz, R; Semertzidis, Y K; Sever, F; Shanahan, P; Sichtermann, E P; Simeoni, F; Smirnov, G I; Staude, A; Steinmetz, A; Stiegler, U; Stuhrmann, H B; Szleper, M; Teichert, K M; Tessarotto, F; Thers, D; Tlaczala, W; Trentalange, S; Tripet, A; Ünel, G; Velasco, M; Vogt, J; Voss, Rüdiger; Weinstein, R; Whitten, C; Windmolders, R; Willumeit, R; Wislicki, W; Witzmann, A; Zanetti, A M; Zaremba, K; Zhao, J


    The polarized target of the Spin Muon Collaboration at CERN was used for deep inelastic muon scattering experiments during 1993 to 1996 with a polarized muon beam to investigate the spin structure of the nucleon. Most of the experiments were carried out with longitudinal target polarization and 190 GeV muons, and some were done with transverse polarization and 100 GeV muons. Protons as well as deuterons were polarized by dynamic nuclear polarization (DNP) in three kinds of solid materials $-$ butanol, ammonia, and deuterated butanol, with maximum degrees of polarization of 94, 91, and 60 \\%, respectively. Considerable attention was paid to the accuracies of the NMR polarization measurements and their analyses. The achieved accuracies were between 2.0 and 3.2 \\%. The SMC target system with two cells of opposite polarizations, each cell 65 cm long and 5 cm in diameter, constitutes the largest polarized target system ever built and facilitates accurate spin asymmetry measurements. The design considerations, the ...

  13. Ratiometric fluorescence imaging of cellular polarity: decrease in mitochondrial polarity in cancer cells. (United States)

    Jiang, Na; Fan, Jiangli; Xu, Feng; Peng, Xiaojun; Mu, Huiying; Wang, Jingyun; Xiong, Xiaoqing


    Mitochondrial polarity strongly influences the intracellular transportation of proteins and interactions between biomacromolecules. The first fluorescent probe capable of the ratiometric imaging of mitochondrial polarity is reported. The probe, termed BOB, has two absorption maxima (λabs = 426 and 561 nm) and two emission maxima--a strong green emission (λem = 467 nm) and a weak red emission (642 nm in methanol)--when excited at 405 nm. However, only the green emission is markedly sensitive to polarity changes, thus providing a ratiometric fluorescence response with a good linear relationship in both extensive and narrow ranges of solution polarity. BOB possesses high specificity to mitochondria (Rr =0.96) that is independent of the mitochondrial membrane potential. The mitochondrial polarity in cancer cells was found to be lower than that of normal cells by ratiometric fluorescence imaging with BOB. The difference in mitochondrial polarity might be used to distinguish cancer cells from normal cells.

  14. Optically-driven red blood cell rotor in linearly polarized laser tweezers

    Indian Academy of Sciences (India)

    Manas Khan; Samarendra K Mohanty; A K Sood


    We have constructed a dual trap optical tweezers set-up around an inverted microscope where both the traps can be independently controlled and manipulated in all the three dimensions. Here we report our observations on rotation of red blood cells (RBCs) in a linearly polarized optical trap. Red blood cells deform and become twisted in hypertonic phosphate buffer saline and when trapped, experience an unbalanced radiation pressure force. The torque generated from the unbalanced force causes the trapped RBC to rotate. Addition of Ca++ ions in the solution, keeping the osmolarity same, makes the cell membranes stiffer and the cells deform less. Thus the speed of rotation of the red blood cells can be controlled, as less deformation and in turn less asymmetry in shape produces less torque under the radiation pressure resulting in slower rotation at the same laser power.

  15. Modelling cell polarization driven by synthetic spatially graded Rac activation.

    Directory of Open Access Journals (Sweden)

    William R Holmes

    Full Text Available The small GTPase Rac is known to be an important regulator of cell polarization, cytoskeletal reorganization, and motility of mammalian cells. In recent microfluidic experiments, HeLa cells endowed with appropriate constructs were subjected to gradients of the small molecule rapamycin leading to synthetic membrane recruitment of a Rac activator and direct graded activation of membrane-associated Rac. Rac activation could thus be triggered independent of upstream signaling mechanisms otherwise responsible for transducing activating gradient signals. The response of the cells to such stimulation depended on exceeding a threshold of activated Rac. Here we develop a minimal reaction-diffusion model for the GTPase network alone and for GTPase-phosphoinositide crosstalk that is consistent with experimental observations for the polarization of the cells. The modeling suggests that mutual inhibition is a more likely mode of cell polarization than positive feedback of Rac onto its own activation. We use a new analytical tool, Local Perturbation Analysis, to approximate the partial differential equations by ordinary differential equations for local and global variables. This method helps to analyze the parameter space and behaviour of the proposed models. The models and experiments suggest that (1 spatially uniform stimulation serves to sensitize a cell to applied gradients. (2 Feedback between phosphoinositides and Rho GTPases sensitizes a cell. (3 Cell lengthening/flattening accompanying polarization can increase the sensitivity of a cell and stabilize an otherwise unstable polarization.

  16. Kif26b controls endothelial cell polarity through the Dishevelled/Daam1-dependent planar cell polarity-signaling pathway. (United States)

    Guillabert-Gourgues, Aude; Jaspard-Vinassa, Beatrice; Bats, Marie-Lise; Sewduth, Raj N; Franzl, Nathalie; Peghaire, Claire; Jeanningros, Sylvie; Moreau, Catherine; Roux, Etienne; Larrieu-Lahargue, Frederic; Dufourcq, Pascale; Couffinhal, Thierry; Duplàa, Cecile


    Angiogenesis involves the coordinated growth and migration of endothelial cells (ECs) toward a proangiogenic signal. The Wnt planar cell polarity (PCP) pathway, through the recruitment of Dishevelled (Dvl) and Dvl-associated activator of morphogenesis (Daam1), has been proposed to regulate cell actin cytoskeleton and microtubule (MT) reorganization for oriented cell migration. Here we report that Kif26b--a kinesin--and Daam1 cooperatively regulate initiation of EC sprouting and directional migration via MT reorganization. First, we find that Kif26b is recruited within the Dvl3/Daam1 complex. Using a three-dimensional in vitro angiogenesis assay, we show that Kif26b and Daam1 depletion impairs tip cell polarization and destabilizes extended vascular processes. Kif26b depletion specifically alters EC directional migration and mislocalized MT organizing center (MTOC)/Golgi and myosin IIB cell rear enrichment. Therefore the cell fails to establish a proper front-rear polarity. Of interest, Kif26b ectopic expression rescues the siDaam1 polarization defect phenotype. Finally, we show that Kif26b functions in MT stabilization, which is indispensable for asymmetrical cell structure reorganization. These data demonstrate that Kif26b, together with Dvl3/Daam1, initiates cell polarity through the control of PCP signaling pathway-dependent activation.

  17. A Predictive Model for Yeast Cell Polarization in Pheromone Gradients. (United States)

    Muller, Nicolas; Piel, Matthieu; Calvez, Vincent; Voituriez, Raphaël; Gonçalves-Sá, Joana; Guo, Chin-Lin; Jiang, Xingyu; Murray, Andrew; Meunier, Nicolas


    Budding yeast cells exist in two mating types, a and α, which use peptide pheromones to communicate with each other during mating. Mating depends on the ability of cells to polarize up pheromone gradients, but cells also respond to spatially uniform fields of pheromone by polarizing along a single axis. We used quantitative measurements of the response of a cells to α-factor to produce a predictive model of yeast polarization towards a pheromone gradient. We found that cells make a sharp transition between budding cycles and mating induced polarization and that they detect pheromone gradients accurately only over a narrow range of pheromone concentrations corresponding to this transition. We fit all the parameters of the mathematical model by using quantitative data on spontaneous polarization in uniform pheromone concentration. Once these parameters have been computed, and without any further fit, our model quantitatively predicts the yeast cell response to pheromone gradient providing an important step toward understanding how cells communicate with each other.

  18. Regulation of polarized extension and planar cell polarity in the cochlea by the vertebrate PCP pathway. (United States)

    Wang, Jianbo; Mark, Sharayne; Zhang, Xiaohui; Qian, Dong; Yoo, Seung-Jong; Radde-Gallwitz, Kristen; Zhang, Yanping; Lin, Xi; Collazo, Andres; Wynshaw-Boris, Anthony; Chen, Ping


    The mammalian auditory sensory organ, the organ of Corti, consists of sensory hair cells with uniformly oriented stereocilia on the apical surfaces and has a distinct planar cell polarity (PCP) parallel to the sensory epithelium. It is not certain how this polarity is achieved during differentiation. Here we show that the organ of Corti is formed from a thicker and shorter postmitotic primordium through unidirectional extension, characteristic of cellular intercalation known as convergent extension. Mutations in the PCP pathway interfere with this extension, resulting a shorter and wider cochlea as well as misorientation of stereocilia. Furthermore, parallel to the homologous pathway in Drosophila melanogaster, a mammalian PCP component Dishevelled2 shows PCP-dependent polarized subcellular localization across the organ of Corti. Taken together, these data suggest that there is a conserved molecular mechanism for PCP pathways in invertebrates and vertebrates and indicate that the mammalian PCP pathway might directly couple cellular intercalations to PCP establishment in the cochlea.

  19. Endomembrane control of cell polarity: Relevance to cancer. (United States)

    Baschieri, Francesco; Farhan, Hesso


    The role of polarity in cancer is an emerging research area and loss of polarity is widely considered an important event in cancer. Among the polarity regulating molecules, the small GTPase Cdc42 was extensively studied. Most attention was given to Cdc42 signaling at the plasma membrane, but whether and how Cdc42 is regulated at endomembranes remained poorly understood. Moreover, whether the endomembrane pool of Cdc42 is of any relevance to cell polarity was unknown. In our recent work, we identified a complex between the Golgi matrix protein GM130 and RasGRF and showed that it is responsible for regulating the Golgi pool of Cdc42, but had no effect on the plasma membrane pool of Cdc42. Depletion of GM130 disrupted apico-basal polarity as well as front-rear polarity, indicating that the spatial pool of Cdc42 is functionally relevant. The biomedical relevance of this finding was supported by the observation than GM130 is progressively lost in colorectal cancer. These findings support a role of the endomembrane pool of Cdc42 in cell polarity and point to a potential role of alterations of this pool in cancer.

  20. Cell Polarity Determinants Establish Asymmetry in MEN Signaling


    Monje-Casas, Fernando; Amon, Angelika


    Components of the Mitotic Exit Network (MEN), a signaling pathway that triggers exit from mitosis, localize to the spindle pole body (SPB) that migrates into the daughter cell during anaphase but are largely absent from the SPB that remains in the mother cell. Through the analysis of one of the determinants of this asymmetry, Bfa1, we find that the machinery responsible for establishing cell polarity and cytoplasmic microtubules collaborate to establish MEN asymmetry. In cells defective in th...

  1. Defective planar cell polarity in polycystic kidney disease. (United States)

    Fischer, Evelyne; Legue, Emilie; Doyen, Antonia; Nato, Faridabano; Nicolas, Jean-François; Torres, Vicente; Yaniv, Moshe; Pontoglio, Marco


    Morphogenesis involves coordinated proliferation, differentiation and spatial distribution of cells. We show that lengthening of renal tubules is associated with mitotic orientation of cells along the tubule axis, demonstrating intrinsic planar cell polarization, and we demonstrate that mitotic orientations are significantly distorted in rodent polycystic kidney models. These results suggest that oriented cell division dictates the maintenance of constant tubule diameter during tubular lengthening and that defects in this process trigger renal tubular enlargement and cyst formation.

  2. Multicellular rosette formation links planar cell polarity to tissue morphogenesis. (United States)

    Blankenship, J Todd; Backovic, Stephanie T; Sanny, Justina S P; Weitz, Ori; Zallen, Jennifer A


    Elongation of the body axis is accompanied by the assembly of a polarized cytoarchitecture that provides the basis for directional cell behavior. We find that planar polarity in the Drosophila embryo is established through a sequential enrichment of actin-myosin cables and adherens junction proteins in complementary surface domains. F-actin accumulation at AP interfaces represents the first break in planar symmetry and occurs independently of proper junctional protein distribution at DV interfaces. Polarized cells engage in a novel program of locally coordinated behavior to generate multicellular rosette structures that form and resolve in a directional fashion. Actin-myosin structures align across multiple cells during rosette formation, and adherens junction proteins assemble in a stepwise fashion during rosette resolution. Patterning genes essential for axis elongation selectively affect the frequency and directionality of rosette formation. We propose that the generation of higher-order rosette structures links local cell interactions to global tissue reorganization during morphogenesis.

  3. Better safe than sorry: TOB1 employs multiple parallel regulatory pathways to keep Th17 cells quiet. (United States)

    Salerno, Fiamma; van Lier, René A W; Wolkers, Monika C


    Th17 cells are key players in antibacterial and antifungal immunity, but have also been implicated in autoimmunity. Interestingly, Th17 cells poorly proliferate upon stimulation, a phenotype that was attributed to a decreased sensitivity to T-cell receptor (TCR) stimulation, and to low IL-2 production by Th17 cells. In this issue of the European Journal of Immunology, Santarlasci et al. [Eur. J. Immunol. 2014. 44: 654-661] shed further light on the molecular mechanism that keeps Th17 cells at bay. They identify the transcriptional regulator TOB1, which not only impairs IL-2 production in Th17 cells, but also blocks the expression of cell cycle genes. Strikingly, TOB1 suppresses Th17-cell proliferation through several pathways, including impaired signal transduction, transcription, and possibly also post-transcriptional regulation.

  4. Planar Cell Polarity Controls Pancreatic Beta Cell Differentiation and Glucose Homeostasis

    DEFF Research Database (Denmark)

    Cortijo, Cedric; Gouzi, Mathieu; Tissir, Fadel


    Planar cell polarity (PCP) refers to the collective orientation of cells within the epithelial plane. We show that progenitor cells forming the ducts of the embryonic pancreas express PCP proteins and exhibit an active PCP pathway. Planar polarity proteins are acquired at embryonic day 11.......5 synchronously to apicobasal polarization of pancreas progenitors. Loss of function of the two PCP core components Celsr2 and Celsr3 shows that they control the differentiation of endocrine cells from polarized progenitors, with a prevalent effect on insulin-producing beta cells. This results in a decreased...

  5. Apicobasal Polarity Controls Lymphocyte Adhesion to Hepatic Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Natalia Reglero-Real


    Full Text Available Loss of apicobasal polarity is a hallmark of epithelial pathologies. Leukocyte infiltration and crosstalk with dysfunctional epithelial barriers are crucial for the inflammatory response. Here, we show that apicobasal architecture regulates the adhesion between hepatic epithelial cells and lymphocytes. Polarized hepatocytes and epithelium from bile ducts segregate the intercellular adhesion molecule 1 (ICAM-1 adhesion receptor onto their apical, microvilli-rich membranes, which are less accessible by circulating immune cells. Upon cell depolarization, hepatic ICAM-1 becomes exposed and increases lymphocyte binding. Polarized hepatic cells prevent ICAM-1 exposure to lymphocytes by redirecting basolateral ICAM-1 to apical domains. Loss of ICAM-1 polarity occurs in human inflammatory liver diseases and can be induced by the inflammatory cytokine tumor necrosis factor alpha (TNF-α. We propose that adhesion receptor polarization is a parenchymal immune checkpoint that allows functional epithelium to hamper leukocyte binding. This contributes to the haptotactic guidance of leukocytes toward neighboring damaged or chronically inflamed epithelial cells that expose their adhesion machinery.

  6. Tissue growth and tumorigenesis in Drosophila: cell polarity and the Hippo pathway. (United States)

    Richardson, Helena E; Portela, Marta


    Cell polarity regulation is critical for defining membrane domains required for the establishment and maintenance of the apical-basal axis in epithelial cells (apico-basal polarity), asymmetric cell divisions, planar organization of tissues (planar cell polarity), and the formation of the front-rear axis in cell migration (front-rear polarity). In the vinegar fly, Drosophila melanogaster, cell polarity regulators also interact with the Hippo tissue growth control signaling pathway. In this review we survey the recent Drosophila literature linking cell polarity regulators with the Hippo pathway in epithelial tissue growth, neural stem cell asymmetric divisions and in cell migration in physiological and tumorigenic settings.

  7. Slit and Robo control cardiac cell polarity and morphogenesis. (United States)

    Qian, Li; Liu, Jiandong; Bodmer, Rolf


    Basic aspects of heart morphogenesis involving migration, cell polarization, tissue alignment, and lumen formation may be conserved between Drosophila and humans, but little is known about the mechanisms that orchestrate the assembly of the heart tube in either organism. The extracellular-matrix molecule Slit and its Robo-family receptors are conserved regulators of axonal guidance. Here, we report a novel role of the Drosophila slit, robo, and robo2 genes in heart morphogenesis. Slit and Robo proteins specifically accumulate at the dorsal midline between the bilateral myocardial progenitors forming a linear tube. Manipulation of Slit localization or its overexpression causes disruption in heart tube alignment and assembly, and slit-deficient hearts show disruptions in cell-polarity marker localization within the myocardium. Similar phenotypes are observed when Robo and Robo2 are manipulated. Rescue experiments suggest that Slit is secreted from the myocardial progenitors and that Robo and Robo2 act in myocardial and pericardial cells, respectively. Genetic interactions suggest a cardiac morphogenesis network involving Slit/Robo, cell-polarity proteins, and other membrane-associated proteins. We conclude that Slit and Robo proteins contribute significantly to Drosophila heart morphogenesis by guiding heart cell alignment and adhesion and/or by inhibiting cell mixing between the bilateral compartments of heart cell progenitors and ensuring proper polarity of the myocardial epithelium.

  8. Role of polarized cell divisions in zebrafish neural tube formation. (United States)

    Clarke, Jon


    Development of epithelial cell polarity and morphogenesis of a central lumen are essential prerequisites for the formation of the vertebrate neural tube. In teleost fish embryos this first involves the formation of a solid neural rod structure that then undergoes a process of cavitation to form a lumen. This process is initiated from a neural plate that has a distinct organization compared to other vertebrates, and involves complex cell intercalations and rearrangements. A key element is a mode of polarized cell division that generates daughters with mirror-image apico-basal polarity. These mirror-symmetric divisions have powerful morphogenetic influence because when they occur in ectopic locations they orchestrate the development of ectopic apical and basal specializations and the development of ectopic neural tubes.

  9. Matrix rigidity optimizes the polarization of stem cells (United States)

    Zemel, Assaf; Rehfeldt, Florian; Brown, Andre; Discher, Dennis; Safran, Samuel


    We present a theoretical model and experiments to explain the non-monotonic dependence of stress-fiber polarization in stem cells on matrix rigidity. The theory generalizes the treatment of elastic inclusions to ``living'' inclusions (cells) whose active polarizability, unlike non-living matter, depends on the feedback of cellular forces that develop in response to matrix stresses. We demonstrate experimentally that the stress fibers in adult mesenchymal stem cells, generally orient parallel to the long axis of the cells, with an anisotropy that depends non-monotonically on substrate stiffness. Consistent with these experiments, our theory predicts that the magnitude of the cellular force increases monotonically with the matrix rigidity while the polarization anisotropy shows a maximum that depends on the cell shape and the elastic modulus of the medium. These findings offer a mechanical correlate for the observation that stem cell differentiation optimizes in a range of matrix rigidities that depends on the tissue type.

  10. A minimal model for spontaneous cell polarization and edge activity in oscillating, rotating and migrating cells

    CERN Document Server

    Raynaud, Franck; Gabella, Chiara; Bornert, Alicia; Sbalzarini, Ivo F; Meister, Jean-Jacques; Verkhovsky, Alexander B


    How the cells break symmetry and organize their edge activity to move directionally is a fun- damental question in cell biology. Physical models of cell motility commonly rely on gradients of regulatory factors and/or feedback from the motion itself to describe polarization of edge activity. Theses approaches, however, fail to explain cell behavior prior to the onset of polarization. Our analysis using the model system of polarizing and moving fish epidermal keratocytes suggests a novel and simple principle of self-organization of cell activity in which local cell-edge dynamics depends on the distance from the cell center, but not on the orientation with respect to the front-back axis. We validate this principle with a stochastic model that faithfully reproduces a range of cell-migration behaviors. Our findings indicate that spontaneous polarization, persistent motion, and cell shape are emergent properties of the local cell-edge dynamics controlled by the distance from the cell center.

  11. Keeping Pace (United States)

    Henderson, Nancy


    This article describes the struggles of two tough moms who team up to start their own company. Fed up with a lack of stylish, properly-fitting shoes for their children with cerebral palsy, they established "Keeping Pace" which currently offers a selection of stylish girls' and boys' athletic sneakers and casual dress shoes for boys, all sold…

  12. Coordinating cell polarity and cell cycle progression: what can we learn from flies and worms? (United States)

    Noatynska, Anna; Tavernier, Nicolas; Gotta, Monica; Pintard, Lionel


    Spatio-temporal coordination of events during cell division is crucial for animal development. In recent years, emerging data have strengthened the notion that tight coupling of cell cycle progression and cell polarity in dividing cells is crucial for asymmetric cell division and ultimately for metazoan development. Although it is acknowledged that such coupling exists, the molecular mechanisms linking the cell cycle and cell polarity machineries are still under investigation. Key cell cycle regulators control cell polarity, and thus influence cell fate determination and/or differentiation, whereas some factors involved in cell polarity regulate cell cycle timing and proliferation potential. The scope of this review is to discuss the data linking cell polarity and cell cycle progression, and the importance of such coupling for asymmetric cell division. Because studies in model organisms such as Caenorhabditis elegans and Drosophila melanogaster have started to reveal the molecular mechanisms of this coordination, we will concentrate on these two systems. We review examples of molecular mechanisms suggesting a coupling between cell polarity and cell cycle progression.

  13. High Throughput Method to Quantify Anterior-Posterior Polarity of T-Cells and Epithelial Cells

    Directory of Open Access Journals (Sweden)

    Susan J. Marriott


    Full Text Available The virologic synapse (VS, which is formed between a virus-infected and uninfected cell, plays a central role in the transmission of certain viruses, such as HIV and HTLV-1. During VS formation, HTLV-1-infected T-cells polarize cellular and viral proteins toward the uninfected T-cell. This polarization resembles anterior-posterior cell polarity induced by immunological synapse (IS formation, which is more extensively characterized than VS formation and occurs when a T-cell interacts with an antigen-presenting cell. One measure of cell polarity induced by both IS or VS formation is the repositioning of the microtubule organizing center (MTOC relative to the contact point with the interacting cell. Here we describe an automated, high throughput system to score repositioning of the MTOC and thereby cell polarity establishment. The method rapidly and accurately calculates the angle between the MTOC and the IS for thousands of cells. We also show that the system can be adapted to score anterior-posterior polarity establishment of epithelial cells. This general approach represents a significant advancement over manual cell polarity scoring, which is subject to experimenter bias and requires more time and effort to evaluate large numbers of cells.

  14. p27Kip1 in cell-cell adhesion and cell polarity

    NARCIS (Netherlands)

    Theard, Delphine Francine


    Hepatocellular carcinoma is one of the more spread cancer in developed countries. This cancer affects hepatocytes, the liver cells acting as a filter between blood and bile. To accomplish this duty, the cells are polarized, which means they present a non-symmetrical morphology with the apical surfac

  15. Lipid polarity and sorting in epithelial cells

    NARCIS (Netherlands)

    van Meer, G.; Simons, K.


    Apical and basolateral membrane domains of epithelial cell plasma membranes possess unique lipid compositions. The tight junction, the structure separating the two domains, forms a diffusion barrier for membrane components and thereby prevents intermixing of the two sets of lipids. The barrier appar

  16. Self-Polarization of Cells in Elastic Gels (United States)

    Zemel, Assaf; Safran, Samuel


    The shape of a cell as well as the rigidity and geometry of its surroundings play an important role in vital cellular processes. The contractile activity of cells provides a generic means by which cells may sense and respond to mechanical features. The matrix stresses, that depend on the elasticity and geometry of cells, feedback on the cells and influence their activity. This suggests a mechanical mechanism by which cells control their shape and forces. We present a quantitative, mechanical model that predicts that cells in an elastic medium can self-polarize to form well ordered stress fibers. We focus on both single cells in a gel, as well as on an ensemble of cells that is confined to some region within the gel. While the magnitude of the cellular forces is found to increase monotonically with the matrix rigidity the anisotropy of the forces, and thus the ability of the cells to polarize, is predicted to depend non-monotonically on the medium's rigidity. We discuss these results with experimental findings and with the observation of an optimal medium elasticity for cell function and differentiation.

  17. Planar cell polarity pathway regulates nephrin endocytosis in developing podocytes. (United States)

    Babayeva, Sima; Rocque, Brittany; Aoudjit, Lamine; Zilber, Yulia; Li, Jane; Baldwin, Cindy; Kawachi, Hiroshi; Takano, Tomoko; Torban, Elena


    The noncanonical Wnt/planar cell polarity (PCP) pathway controls a variety of cell behaviors such as polarized protrusive cell activity, directional cell movement, and oriented cell division and is crucial for the normal development of many tissues. Mutations in the PCP genes cause malformation in multiple organs. Recently, the PCP pathway was shown to control endocytosis of PCP and non-PCP proteins necessary for cell shape remodeling and formation of specific junctional protein complexes. During formation of the renal glomerulus, the glomerular capillary becomes enveloped by highly specialized epithelial cells, podocytes, that display unique architecture and are connected via specialized cell-cell junctions (slit diaphragms) that restrict passage of protein into the urine; podocyte differentiation requires active remodeling of cytoskeleton and junctional protein complexes. We report here that in cultured human podocytes, activation of the PCP pathway significantly stimulates endocytosis of the core slit diaphragm protein, nephrin, via a clathrin/β-arrestin-dependent endocytic route. In contrast, depletion of the PCP protein Vangl2 leads to an increase of nephrin at the cell surface; loss of Vangl2 functions in Looptail mice results in disturbed glomerular maturation. We propose that the PCP pathway contributes to podocyte development by regulating nephrin turnover during junctional remodeling as the cells differentiate.

  18. Regulation of bacterial cell polarity by small GTPases. (United States)

    Keilberg, Daniela; Søgaard-Andersen, Lotte


    Bacteria are polarized with many proteins localizing dynamically to specific subcellular sites. Two GTPase families have important functions in the regulation of bacterial cell polarity, FlhF homologues and small GTPases of the Ras superfamily. The latter consist of only a G domain and are widespread in bacteria. The rod-shaped Myxococcus xanthus cells have two motility systems, one for gliding and one that depends on type IV pili. The function of both systems hinges on proteins that localize asymmetrically to the cell poles. During cellular reversals, these asymmetrically localized proteins are released from their respective poles and then bind to the opposite pole, resulting in an inversion of cell polarity. Here, we review genetic, cell biological, and biochemical analyses that identified two modules containing small Ras-like GTPases that regulate the dynamic polarity of motility proteins. The GTPase SofG interacts directly with the bactofilin cytoskeletal protein BacP to ensure polar localization of type IV pili proteins. In the second module, the small GTPase MglA, its cognate GTPase activating protein (GAP) MglB, and the response regulator RomR localize asymmetrically to the poles and sort dynamically localized motility proteins to the poles. During reversals, MglA, MglB, and RomR switch poles, in that way inducing the relocation of dynamically localized motility proteins. Structural analyses have demonstrated that MglB has a Roadblock/LC7 fold, the central β2 strand in MglA undergoes an unusual screw-type movement upon GTP binding, MglA contains an intrinsic Arg finger required for GTP hydrolysis, and MglA and MglB form an unusual G protein/GAP complex with a 1:2 stoichiometry.

  19. Planar Cell Polarity Signaling Pathway in Congenital Heart Diseases

    Directory of Open Access Journals (Sweden)

    Gang Wu


    Full Text Available Congenital heart disease (CHD is a common cardiac disorder in humans. Despite many advances in the understanding of CHD and the identification of many associated genes, the fundamental etiology for the majority of cases remains unclear. The planar cell polarity (PCP signaling pathway, responsible for tissue polarity in Drosophila and gastrulation movements and cardiogenesis in vertebrates, has been shown to play multiple roles during cardiac differentiation and development. The disrupted function of PCP signaling is connected to some CHDs. Here, we summarize our current understanding of how PCP factors affect the pathogenesis of CHD.

  20. Protein-protein interactions and genome engineering : novel strategies to study cell polarity

    NARCIS (Netherlands)

    Waaijers, S.


    Cell polarity is a fundamental property of cells. The identification of conserved polarity regulators that control polarity in a variety of distinct tissues raises a number of questions. How are the same components used and integrated in tissue-specific ways to give rise to the wide variety of polar

  1. Current concepts of hair cell differentiation and planar cell polarity in inner ear sensory organs. (United States)

    Sienknecht, Ulrike J


    Phylogenetically and ontogenetically, vertebrate development led to the generation of several inner ear sensory organs. During embryogenesis, cell fate specification determines whether each progenitor cell differentiates into a sensory hair cell or a supporting cell within the common sensory primordium. Finally, all sensory epithelia of the inner ear consist of a hair cell/supporting cell mosaic, albeit with anatomical differences depending on the sensory organ type. Hair cells develop a polarized bundle of stereovilli that is of functional importance for mechanotransduction. After initiating stereovillar development, hair cells align their bundles in a coordinated fashion, generating a characteristic hair cell orientation pattern, a process referred to as planar cell polarity (PCP). The pathway that controls PCP in the inner ear needs both to establish the development of a polarized morphology of the stereovillar bundle of the hair cell and to organize a systematic hair cell alignment. Because the hair cell orientation patterns of the various inner ear organs and vertebrate species differ fundamentally, it becomes apparent that in vertebrates, different aspects of PCP need to be independently controlled. In spite of important progress recently gained in the field of PCP research, we still need to identify the mechanisms (1) that initiate molecular asymmetries in cells, (2) that guide the transmission of polarity information from cell to cell, and (3) that consistently translate such polarity information into morphological asymmetries of hair cells.

  2. Organising cells into tissues: new roles for cell adhesion molecules in planar cell polarity. (United States)

    Saburi, Sakura; McNeill, Helen


    Planar cell polarity (PCP) is the coordinated organization of cells within the plane of the epithelium, first described in Drosophila. A Frizzled signalling pathway dedicated to PCP (the non-canonical Frizzled pathway) acts through Dishevelled and small G proteins, as does the classical Wnt pathway, but then diverges downstream of Dishevelled. Recent studies have demonstrated a crucial role for several atypical cadherin molecules (Fat, Dachsous and Flamingo) in controlling PCP signalling. Recent work has also indicated that the first sign of PCP during development is the polarized localization of PCP proteins (Frizzled, Flamingo, Dishevelled, etc). Exciting new data reveal that this PCP pathway is conserved to man.

  3. Positive Feedback Keeps Duration of Mitosis Temporally Insulated from Upstream Cell-Cycle Events


    Araujo, Ana Rita; Gelens, Lendert; Sheriff, Rahuman; Santos, Silvia D.M.


    Cell division is characterized by a sequence of events by which a cell gives rise to two daughter cells. Quan- titative measurements of cell-cycle dynamics in sin- gle cells showed that despite variability in G1-, S-, and G2 phases, duration of mitosis is short and remarkably constant. Surprisingly, there is no corre- lation between cell-cycle length and mitotic duration, suggesting that mitosis is temporally insulated from variability in earlier cell-cycle phases. By combining live cell imag...

  4. Planar Cell Polarity Pathway in Kidney Development and Function

    Directory of Open Access Journals (Sweden)

    Brittany Rocque


    Full Text Available The evolutionarily conserved planar cell polarity (PCP signaling pathway controls tissue polarity within the plane orthogonal to the apical-basal axis. PCP was originally discovered in Drosophila melanogaster where it is required for the establishment of a uniform pattern of cell structures and appendages. In vertebrates, including mammals, the PCP pathway has been adapted to control various morphogenetic processes that are critical for tissue and organ development. These include convergent extension (crucial for neural tube closure and cochlear duct development and oriented cell division (needed for tubular elongation, ciliary tilting that enables directional fluid flow, and other processes. Recently, strong evidence has emerged to implicate the PCP pathway in vertebrate kidney development. In this review, we will describe the experimental data revealing the role of PCP signaling in nephrogenesis and kidney disease.

  5. Mathematical modeling of planar cell polarity to understand domineering nonautonomy. (United States)

    Amonlirdviman, Keith; Khare, Narmada A; Tree, David R P; Chen, Wei-Shen; Axelrod, Jeffrey D; Tomlin, Claire J


    Planar cell polarity (PCP) signaling generates subcellular asymmetry along an axis orthogonal to the epithelial apical-basal axis. Through a poorly understood mechanism, cell clones that have mutations in some PCP signaling components, including some, but not all, alleles of the receptor frizzled, cause polarity disruptions of neighboring wild-type cells, a phenomenon referred to as domineering nonautonomy. Here, a contact-dependent signaling hypothesis, derived from experimental results, is shown by reaction-diffusion, partial differential equation modeling and simulation to fully reproduce PCP phenotypes, including domineering nonautonomy, in the Drosophila wing. The sufficiency of this model and the experimental validation of model predictions reveal how specific protein-protein interactions produce autonomy or domineering nonautonomy.

  6. Satellite Cells in Muscular Dystrophy - Lost in Polarity. (United States)

    Chang, Natasha C; Chevalier, Fabien P; Rudnicki, Michael A


    Recent findings employing the mdx mouse model for Duchenne muscular dystrophy (DMD) have revealed that muscle satellite stem cells play a direct role in contributing to disease etiology and progression of DMD, the most common and severe form of muscular dystrophy. Lack of dystrophin expression in DMD has critical consequences in satellite cells including an inability to establish cell polarity, abrogation of asymmetric satellite stem-cell divisions, and failure to enter the myogenic program. Thus, muscle wasting in dystrophic mice is not only caused by myofiber fragility but is exacerbated by intrinsic satellite cell dysfunction leading to impaired regeneration. Despite intense research and clinical efforts, there is still no effective cure for DMD. In this review we highlight recent research advances in DMD and discuss the current state of treatment and, importantly, how we can incorporate satellite cell-targeted therapeutic strategies to correct satellite cell dysfunction in DMD.

  7. Rho1-Wnd signaling regulates loss-of-cell polarity-induced cell invasion in Drosophila. (United States)

    Ma, X; Chen, Y; Zhang, S; Xu, W; Shao, Y; Yang, Y; Li, W; Li, M; Xue, L


    Both cell polarity and c-Jun N-terminal kinase (JNK) activity are essential to the maintenance of tissue homeostasis, and disruption of either is commonly seen in cancer progression. Despite the established connection between loss-of-cell polarity and JNK activation, much less is known about the molecular mechanism by which aberrant cell polarity induces JNK-mediated cell migration and tumor invasion. Here we show results from a genetic screen using an in vivo invasion model via knocking down cell polarity gene in Drosophila wing discs, and identify Rho1-Wnd signaling as an important molecular link that mediates loss-of-cell polarity-triggered JNK activation and cell invasion. We show that Wallenda (Wnd), a protein kinase of the mitogen-activated protein kinase kinase kinase family, by forming a complex with the GTPase Rho1, is both necessary and sufficient for Rho1-induced JNK-dependent cell invasion, MMP1 activation and epithelial-mesenchymal transition. Furthermore, Wnd promotes cell proliferation and tissue growth through wingless production when apoptosis is inhibited by p35. Finally, Wnd shows oncogenic cooperation with Ras(V12) to trigger tumor growth in eye discs and causes invasion into the ventral nerve cord. Together, our data not only provides a novel mechanistic insight on how cell polarity loss contributes to cell invasion, but also highlights the value of the Drosophila model system to explore human cancer biology.

  8. Order and stochastic dynamics in Drosophila planar cell polarity.

    Directory of Open Access Journals (Sweden)

    Yoram Burak


    Full Text Available Cells in the wing blade of Drosophila melanogaster exhibit an in-plane polarization causing distal orientation of hairs. Establishment of the Planar Cell Polarity (PCP involves intercellular interactions as well as a global orienting signal. Many of the genetic and molecular components underlying this process have been experimentally identified and a recently advanced system-level model has suggested that the observed mutant phenotypes can be understood in terms of intercellular interactions involving asymmetric localization of membrane bound proteins. Among key open questions in understanding the emergence of ordered polarization is the effect of stochasticity and the role of the global orienting signal. These issues relate closely to our understanding of ferromagnetism in physical systems. Here we pursue this analogy to understand the emergence of PCP order. To this end we develop a semi-phenomenological representation of the underlying molecular processes and define a "phase diagram" of the model which provides a global view of the dependence of the phenotype on parameters. We show that the dynamics of PCP has two regimes: rapid growth in the amplitude of local polarization followed by a slower process of alignment which progresses from small to large scales. We discuss the response of the tissue to various types of orienting signals and show that global PCP order can be achieved with a weak orienting signal provided that it acts during the early phase of the process. Finally we define and discuss some of the experimental predictions of the model.

  9. Planar cell polarity, ciliogenesis and neural tube defects. (United States)

    Wallingford, John B


    Cilia are microtubule-based protrusions that are found on the surface of most vertebrate cells. Long studied by cell biologists, these organelles have recently caught the attention of developmental biologists and human geneticists. In this review, I will discuss recent findings suggesting a link between cilia and the planar cell polarity signaling cascade. In particular, I will focus on how this interaction may influence the process of neural tube closure and how these results may be relevant to our understanding of common human birth defects in which neural tube closure is compromised.

  10. Endocytic turnover of Rab8 controls cell polarization (United States)

    Vidal-Quadras, Maite; Holst, Mikkel R.; Larsson, Elin; Hachimi, Mariam; Yau, Wai-Lok; Peränen, Johan; Martín-Belmonte, Fernando


    ABSTRACT Adaptation of cell shape and polarization through the formation and retraction of cellular protrusions requires balancing of endocytosis and exocytosis combined with fine-tuning of the local activity of small GTPases like Rab8. Here, we show that endocytic turnover of the plasma membrane at protrusions is directly coupled to surface removal and inactivation of Rab8. Removal is induced by reduced membrane tension and mediated by the GTPase regulator associated with focal adhesion kinase-1 (GRAF1, also known as ARHGAP26), a regulator of clathrin-independent endocytosis. GRAF1-depleted cells were deficient in multi-directional spreading and displayed elevated levels of GTP-loaded Rab8, which was accumulated at the tips of static protrusions. Furthermore, GRAF1 depletion impaired lumen formation and spindle orientation in a 3D cell culture system, indicating that GRAF1 activity regulates polarity establishment. Our data suggest that GRAF1-mediated removal of Rab8 from the cell surface restricts its activity during protrusion formation, thereby facilitating dynamic adjustment of the polarity axis. PMID:28137756

  11. Gpr125 modulates Dishevelled distribution and planar cell polarity signaling. (United States)

    Li, Xin; Roszko, Isabelle; Sepich, Diane S; Ni, Mingwei; Hamm, Heidi E; Marlow, Florence L; Solnica-Krezel, Lilianna


    During vertebrate gastrulation, Wnt/planar cell polarity (PCP) signaling orchestrates polarized cell behaviors underlying convergence and extension (C&E) movements to narrow embryonic tissues mediolaterally and lengthen them anteroposteriorly. Here, we have identified Gpr125, an adhesion G protein-coupled receptor, as a novel modulator of the Wnt/PCP signaling system. Excess Gpr125 impaired C&E movements and the underlying cell and molecular polarities. Reduced Gpr125 function exacerbated the C&E and facial branchiomotor neuron (FBMN) migration defects of embryos with reduced Wnt/PCP signaling. At the molecular level, Gpr125 recruited Dishevelled to the cell membrane, a prerequisite for Wnt/PCP activation. Moreover, Gpr125 and Dvl mutually clustered one another to form discrete membrane subdomains, and the Gpr125 intracellular domain directly interacted with Dvl in pull-down assays. Intriguingly, Dvl and Gpr125 were able to recruit a subset of PCP components into membrane subdomains, suggesting that Gpr125 may modulate the composition of Wnt/PCP membrane complexes. Our study reveals a role for Gpr125 in PCP-mediated processes and provides mechanistic insight into Wnt/PCP signaling.

  12. Hexagonal packing of Drosophila wing epithelial cells by the planar cell polarity pathway. (United States)

    Classen, Anne-Kathrin; Anderson, Kurt I; Marois, Eric; Eaton, Suzanne


    The mechanisms that order cellular packing geometry are critical for the functioning of many tissues, but they are poorly understood. Here, we investigate this problem in the developing wing of Drosophila. The surface of the wing is decorated by hexagonally packed hairs that are uniformly oriented by the planar cell polarity pathway. They are constructed by a hexagonal array of wing epithelial cells. Wing epithelial cells are irregularly arranged throughout most of development, but they become hexagonally packed shortly before hair formation. During the process, individual cell boundaries grow and shrink, resulting in local neighbor exchanges, and Cadherin is actively endocytosed and recycled through Rab11 endosomes. Hexagonal packing depends on the activity of the planar cell polarity proteins. We propose that these proteins polarize trafficking of Cadherin-containing exocyst vesicles during junction remodeling. This may be a common mechanism for the action of planar cell polarity proteins in diverse systems.

  13. Optimal matrix rigidity for stress fiber polarization in stem cells (United States)

    Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.


    The shape and differentiation of human mesenchymal stem cells is especially sensitive to the rigidity of their environment; the physical mechanisms involved are unknown. A theoretical model and experiments demonstrate here that the polarization/alignment of stress-fibers within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix whose polarizability, unlike dead matter, depends on the feedback of cellular forces that develop in response to matrix stresses. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress-fibers parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress-fibers in stem cells. These findings offer a first physical insight for the dependence of stem cell differentiation on tissue elasticity. PMID:20563235

  14. Cell polarity determinants establish asymmetry in MEN signaling. (United States)

    Monje-Casas, Fernando; Amon, Angelika


    Components of the mitotic exit network (MEN), a signaling pathway that triggers exit from mitosis, localize to the spindle pole body (SPB) that migrates into the daughter cell during anaphase but are largely absent from the SPB that remains in the mother cell. Through the analysis of one of the determinants of this asymmetry, Bfa1, we find that the machinery responsible for establishing cell polarity and cytoplasmic microtubules collaborate to establish MEN asymmetry. In cells defective in the Cdc42 signaling pathway or the formin Bni1, Bfa1 localizes to both SPBs. The quantitative analysis of Bfa1 localization further shows that Bfa1 can associate with both SPBs in a transient and highly dynamic fashion, but the protein is stabilized on the SPB that migrates into the daughter cell during anaphase through microtubule-bud cortex interactions. Our results indicate that mother-daughter cell asymmetry determinants establish MEN signaling asymmetry through microtubule-bud cortex interactions.

  15. Cell-alignment patterns in the collective migration of cells with polarized adhesion (United States)

    Matsushita, Katsuyoshi


    Dictyostelium discoideum (Dd) utilizes inhomogeneities in the distribution of cell-cell adhesion molecules on cell membranes for collective cell migration. A simple example of an inhomogeneity is a front-side (leading-edge) polarization in the distribution at the early streaming stage. Experiments have shown that the polarized cell-cell adhesion induces side-by-side contact between cells [Beug et al., Nature (London) 274, 445 (1978), 10.1038/274445a0]. This result is counterintuitive, as one would expect cells to align front to front in contact with each other on the basis of front-side polarization. In this work, we theoretically examine whether front-side polarization induces side-by-side contact in collective cell migration. We construct a model for expressing cells with this polarization based on the two-dimensional cellular Potts model. By a numerical simulation with this model, we find cell-cell alignment wherein cells form lateral arrays with side-by-side contacts as observed in the experiments.

  16. Heme and non-heme iron transporters in non-polarized and polarized cells

    Directory of Open Access Journals (Sweden)

    Yasui Yumiko


    Full Text Available Abstract Background Heme and non-heme iron from diet, and recycled iron from hemoglobin are important products of the synthesis of iron-containing molecules. In excess, iron is potentially toxic because it can produce reactive oxygen species through the Fenton reaction. Humans can absorb, transport, store, and recycle iron without an excretory system to remove excess iron. Two candidate heme transporters and two iron transporters have been reported thus far. Heme incorporated into cells is degraded by heme oxygenases (HOs, and the iron product is reutilized by the body. To specify the processes of heme uptake and degradation, and the reutilization of iron, we determined the subcellular localizations of these transporters and HOs. Results In this study, we analyzed the subcellular localizations of 2 isoenzymes of HOs, 4 isoforms of divalent metal transporter 1 (DMT1, and 2 candidate heme transporters--heme carrier protein 1 (HCP1 and heme responsive gene-1 (HRG-1--in non-polarized and polarized cells. In non-polarized cells, HCP1, HRG-1, and DMT1A-I are located in the plasma membrane. In polarized cells, they show distinct localizations: HCP1 and DMT1A-I are located in the apical membrane, whereas HRG-1 is located in the basolateral membrane and lysosome. 16Leu at DMT1A-I N-terminal cytosolic domain was found to be crucial for plasma membrane localization. HOs are located in smooth endoplasmic reticulum and colocalize with NADPH-cytochrome P450 reductase. Conclusions HCP1 and DMT1A-I are localized to the apical membrane, and HRG-1 to the basolateral membrane and lysosome. These findings suggest that HCP1 and DMT1A-I have functions in the uptake of dietary heme and non-heme iron. HRG-1 can transport endocytosed heme from the lysosome into the cytosol. These localization studies support a model in which cytosolic heme can be degraded by HOs, and the resulting iron is exported into tissue fluids via the iron transporter ferroportin 1, which is

  17. Centrosome polarization in T cells: a task for formins

    Directory of Open Access Journals (Sweden)

    Laura eAndrés-Delgado


    Full Text Available T-cell antigen receptor (TCR engagement triggers the rapid reorientation of the centrosome, which is associated with the secretory machinery, towards the immunological synapse (IS for polarized protein trafficking. Recent evidence indicates that upon TCR triggering the INF2 formin, together with the formins DIA1 and FMNL1, promotes the formation of a specialized array of stable detyrosinated MTs that breaks the symmetrical organization of the T-cell microtubule (MT cytoskeleton. The detyrosinated MT array and TCR-induced tyrosine phosphorylation should coincide for centrosome polarization. We propose that the pushing forces produced by the detyrosinated MT array, which modify the position of the centrosome, in concert with Src kinase dependent TCR signaling, which provide the reference frame with respect to which the centrosome reorients, result in the repositioning of the centrosome to the IS.

  18. Appearance of differentiated cells derived from polar body nuclei in the silkworm, Bombyx mori

    Directory of Open Access Journals (Sweden)

    Hiroki eSakai


    Full Text Available AbstractIn Bombyx mori, polar body nuclei are observed until 9h after egg lying, however, the fate of polar body nuclei remains unclear. To examine the fate of polar body nuclei, we employed a mutation of serosal cell pigmentation, pink-eyed white egg (pe. The heterozygous pe/+pe females produced black serosal cells in white eggs, while pe/pe females did not produce black serosal cells in white eggs. These results suggest that the appearance of black serosal cells in white eggs depends on the genotype (pe/ +pe of the mother. Because the polar body nuclei had +pe genes in the white eggs laid by a pe/ +pe female, polar body nuclei participate in development and differentiate into functional cell (serosal cells. Analyses of serosal cells pigmentation indicated that approximately 30% of the eggs contained polar-body-nucleus-derived cells. These results demonstrate that polar-body-nucleus-derived cells appeared at a high frequency under natural conditions. Approximately 80% of polar-body-nucleus-derived cells appeared near the anterior pole and the dorsal side, which is opposite to where embryogenesis occurs. The number of cells derived from the polar body nuclei was very low. Approximately 26 % of these eggs contained only one black serosal cell. PCR-based analysis revealed that the polar-body-nucleus-derived cells disappeared in late embryonic stages (stage 25. Overall, polar-body-nuclei-derived cells were unlikely to contribute to embryos.

  19. Dynamics of cell polarity in tissue morphogenesis: a comparative view from Drosophila and Ciona. (United States)

    Veeman, Michael T; McDonald, Jocelyn A


    Tissues in developing embryos exhibit complex and dynamic rearrangements that shape forming organs, limbs, and body axes. Directed migration, mediolateral intercalation, lumen formation, and other rearrangements influence the topology and topography of developing tissues. These collective cell behaviors are distinct phenomena but all involve the fine-grained control of cell polarity. Here we review recent findings in the dynamics of polarized cell behavior in both the Drosophila ovarian border cells and the Ciona notochord. These studies reveal the remarkable reorganization of cell polarity during organ formation and underscore conserved mechanisms of developmental cell polarity including the Par/atypical protein kinase C (aPKC) and planar cell polarity pathways. These two very different model systems demonstrate important commonalities but also key differences in how cell polarity is controlled in tissue morphogenesis. Together, these systems raise important, broader questions on how the developmental control of cell polarity contributes to morphogenesis of diverse tissues across the metazoa.

  20. Keeping the intracellular vitamin C at a physiologically relevant level in endothelial cell culture

    DEFF Research Database (Denmark)

    Frikke-Schmidt, Henriette Rønne; Lykkesfeldt, Jens


    It is generally accepted that the addition of vitamin C to cell culture medium improves cell growth. However, once added, the vitamin C concentration declines rapidly. This situation differs from the in vivo environment where the endothelium is constantly supplied with ascorbate from the blood...

  1. Conversion of commercial si solar cells to keep their efficient performance at 15 suns

    Energy Technology Data Exchange (ETDEWEB)

    Coello, J. [Instituto Tecnologico y de Energias Renovables, Poligono Industrial de Granadilla, Tenerife (Spain); Castro, M.; Anton, I.; Sala, G. [Ciudad Univ., Madrid (Spain). Inst. de Energia Solar; Vazquez, M.A. [Isofoton, S.A., Poligono Industrial Santa Cruz, Malaga (Spain)


    The screen-printing method is an economical metallization technique used by most manufacturers of conventional silicon solar cells. This method limits the cells' use under concentrated light owing to high series resistance losses caused, among other reasons, by low metal density in the fingers. This paper describes increasing the finger metal density by electrolytic deposition. The electrolytic deposition of silver is an economical, controllable and readily commercializable deposition method to reduce the front and back metallization series resistance contributions. With an optimized grid design, compatible with 1 sun silicon cell technology, and later electrolytic silver deposition we have obtained cells that maintain their efficiency up to 15 suns. In addition, an analysis of the performance of these cells under uniform and non-uniform illumination were carried out on n{sup +}p and n{sup +}pn{sup +} structures. (author)

  2. Cell polarity in plants: when two do the same, it is not the same.... (United States)

    Dettmer, Jan; Friml, Jiří


    In unicellular and multicellular organisms, cell polarity is essential for a wide range of biological processes. An important feature of cell polarity is the asymmetric distribution of proteins in or at the plasma membrane. In plants such polar localized proteins play various specific roles ranging from organizing cell morphogenesis, asymmetric cell division, pathogen defense, nutrient transport and establishment of hormone gradients for developmental patterning. Moreover, flexible respecification of cell polarities enables plants to adjust their physiology and development to environmental changes. Having evolved multicellularity independently and lacking major cell polarity mechanisms of animal cells, plants came up with alternative solutions to generate and respecify cell polarity as well as to regulate polar domains at the plasma membrane.

  3. [The multiple links between cilia and planar cell polarity]. (United States)

    Ezan, Jérôme; Montcouquiol, Mireille


    Since our seminal study in 2003, much has been written about core planar cell polarity (core PCP) signaling and the inner ear. In just a few years, and using the inner ear as a model system, our understanding of the molecular basis of this signaling pathway and how it can influence the development of tissues in mammals has increased considerably. Recently, a number of studies using various animal models of development have uncovered original relationships between the cilia and PCP, and the study of the hair cells of the inner ear has helped elucidating one of these links. In this review, we highlight the differences of PCP signaling between mammals and invertebrates. In the light of recent results, we sum up our current knowledge about PCP signaling in the mammalian cochlear epithelium and we discuss the impact of recent data in the field. We focus our attention on the interrelationship between asymmetric polarity complexes and the position of the cilium, which is essential for the establishment of the overall tissue polarity.

  4. Planar cell polarity: heading in the right direction. (United States)

    Kiefer, Julie C


    Epithelial cells are patterned not only along their apical-basolateral axis, but also along the plane of the epithelial sheet; the latter event is regulated by the planar cell polarity (PCP) pathway. PCP regulates diverse outputs, such as the distal placement of a hair in all cells of the Drosophila wing, and convergent extension movements during gastrulation in the vertebrate embryo. This primer describes the molecular mechanisms that initiate and establish PCP, as well as biochemical pathways that translate PCP signaling to cell type-specific patterning events. The primer concludes with a discussion of current topics in the field with two PCP researchers, Matt Kelley, Ph.D., and Helen McNeill, Ph.D.

  5. Dual polarization of microglia isolated from mixed glial cell cultures. (United States)

    Ju, Lili; Zeng, Hui; Chen, Yun; Wu, Yanhong; Wang, Beibei; Xu, Qunyuan


    Microglia are versatile immune effector cells of the CNS and are sensitive to various stimuli. The different methods used to isolate microglia may affect some of their characteristics, such as their polarization state. The influence of cell sorting methods on the polarization state of microglia has never been studied. Mixed glial culture system (MGCS) and magnetic activated cell sorting (MACS) are two methods that are commonly used to purify microglia. This study compares the immunological states between microglia isolated by MGCS and microglia isolated by MACS. We show that microglia isolated by MGCS exhibit a stronger immune-activated state than microglia isolated by MACS. They present an elevated phagocytic ability and high levels of markers associated with classical activation (M1) and alternative activation (M2). In addition, high levels of M1-type and M2-type chemokine (C-C motif) ligand 2 and transforming growth factor-β1 were detected in the culture medium of mixed glial cells. Our results show that microglia isolated by MGCS are in an immune-activated state, whereas microglia isolated by MACS appear to be closer to their primary in vivo state. Therefore, the immune status of microglia, depending on the protocol used to purify them, should be carefully considered in neuropathology research.

  6. Prickle/spiny-legs isoforms control the polarity of the apical microtubule network in planar cell polarity. (United States)

    Olofsson, Jessica; Sharp, Katherine A; Matis, Maja; Cho, Bomsoo; Axelrod, Jeffrey D


    Microtubules (MTs) are substrates upon which plus- and minus-end directed motors control the directional movement of cargos that are essential for generating cell polarity. Although centrosomal MTs are organized with plus-ends away from the MT organizing center, the regulation of non-centrosomal MT polarity is poorly understood. Increasing evidence supports the model that directional information for planar polarization is derived from the alignment of a parallel apical network of MTs and the directional MT-dependent trafficking of downstream signaling components. The Fat/Dachsous/Four-jointed (Ft/Ds/Fj) signaling system contributes to orienting those MTs. In addition to previously defined functions in promoting asymmetric subcellular localization of 'core' planar cell polarity (PCP) proteins, we find that alternative Prickle (Pk-Sple) protein isoforms control the polarity of this MT network. This function allows the isoforms of Pk-Sple to differentially determine the direction in which asymmetry is established and therefore, ultimately, the direction of tissue polarity. Oppositely oriented signals that are encoded by oppositely oriented Fj and Ds gradients produce the same polarity outcome in different tissues or compartments, and the tissue-specific activity of alternative Pk-Sple protein isoforms has been observed to rectify the interpretation of opposite upstream directional signals. The control of MT polarity, and thus the directionality of apical vesicle traffic, by Pk-Sple provides a mechanism for this rectification.

  7. Coordination of planar cell polarity pathways through Spiny-legs. (United States)

    Ambegaonkar, Abhijit A; Irvine, Kenneth D


    Morphogenesis and physiology of tissues and organs requires planar cell polarity (PCP) systems that orient and coordinate cells and their behaviors, but the relationship between PCP systems has been controversial. We have characterized how the Frizzled and Dachsous-Fat PCP systems are connected through the Spiny-legs isoform of the Prickle-Spiny-legs locus. Two different components of the Dachsous-Fat system, Dachsous and Dachs, can each independently interact with Spiny-legs and direct its localization in vivo. Through characterization of the contributions of Prickle, Spiny-legs, Dachsous, Fat, and Dachs to PCP in the Drosophila wing, eye, and abdomen, we define where Dachs-Spiny-legs and Dachsous-Spiny-legs interactions contribute to PCP, and provide a new understanding of the orientation of polarity and the basis of PCP phenotypes. Our results support the direct linkage of PCP systems through Sple in specific locales, while emphasizing that cells can be subject to and must ultimately resolve distinct, competing PCP signals.

  8. Planar cell polarity genes and neural tube closure. (United States)

    Ueno, Naoto; Greene, Nicholas D E


    Closure of the neural tube is essential for normal development of the brain and spinal cord. Failure of closure results in neural tube defects (NTDs), common and clinically severe congenital malformations whose molecular mechanisms remain poorly understood. On the other hand, it is increasingly well established that common molecular mechanisms are employed to regulate morphogenesis of multicellular organisms. For example, signaling triggered by polypeptide growth factors is highly conserved among species and utilized in multiple developmental processes. Recent studies have revealed that the Drosophila planar cell polarity (PCP) pathway, which directs position and direction of wing hairs on the surface of the fly wing, is well conserved, and orthologs of several genes encoding components of the pathway are also found in vertebrates. Interestingly, in vertebrates, this signaling pathway appears to be co-opted to regulate "convergent extension" cell movements during gastrulation. Disruption of vertebrate PCP genes in Xenopus laevis or zebrafish causes severe gastrulation defects or the shortening of the trunk, as well as mediolateral expansion of somites. In Xenopus, in which the neural tube closes by elevation and fusion of neural folds, inhibition of convergent extension can also prevent neural tube closure causing a "spina bifida-like" appearance. Furthermore, several of the genes involved in the PCP pathway have recently been shown to be required for neural tube closure in the mouse, since mutation of these genes causes NTDs. Therefore, understanding the mechanisms underlying the establishment of cell polarity in Drosophila may provide important clues to the molecular basis of NTDs.

  9. Ectopic KNOX Expression Affects Plant Development by Altering Tissue Cell Polarity and Identity[OPEN (United States)

    Rebocho, Alexandra B.


    Plant development involves two polarity types: tissue cell (asymmetries within cells are coordinated across tissues) and regional (identities vary spatially across tissues) polarity. Both appear altered in the barley (Hordeum vulgare) Hooded mutant, in which ectopic expression of the KNOTTED1-like Homeobox (KNOX) gene, BKn3, causes inverted polarity of differentiated hairs and ectopic flowers, in addition to wing-shaped outgrowths. These lemma-specific effects allow the spatiotemporal analysis of events following ectopic BKn3 expression, determining the relationship between KNOXs, polarity, and shape. We show that tissue cell polarity, based on localization of the auxin transporter SISTER OF PINFORMED1 (SoPIN1), dynamically reorients as ectopic BKn3 expression increases. Concurrently, ectopic expression of the auxin importer LIKE AUX1 and boundary gene NO APICAL MERISTEM is activated. The polarity of hairs reflects SoPIN1 patterns, suggesting that tissue cell polarity underpins oriented cell differentiation. Wing cell files reveal an anisotropic growth pattern, and computational modeling shows how polarity guiding growth can account for this pattern and wing emergence. The inverted ectopic flower orientation does not correlate with SoPIN1, suggesting that this form of regional polarity is not controlled by tissue cell polarity. Overall, the results suggest that KNOXs trigger different morphogenetic effects through interplay between tissue cell polarity, identity, and growth. PMID:27553356

  10. Ectopic KNOX Expression Affects Plant Development by Altering Tissue Cell Polarity and Identity. (United States)

    Richardson, Annis Elizabeth; Rebocho, Alexandra B; Coen, Enrico S


    Plant development involves two polarity types: tissue cell (asymmetries within cells are coordinated across tissues) and regional (identities vary spatially across tissues) polarity. Both appear altered in the barley (Hordeum vulgare) Hooded mutant, in which ectopic expression of the KNOTTED1-like Homeobox (KNOX) gene, BKn3, causes inverted polarity of differentiated hairs and ectopic flowers, in addition to wing-shaped outgrowths. These lemma-specific effects allow the spatiotemporal analysis of events following ectopic BKn3 expression, determining the relationship between KNOXs, polarity, and shape. We show that tissue cell polarity, based on localization of the auxin transporter SISTER OF PINFORMED1 (SoPIN1), dynamically reorients as ectopic BKn3 expression increases. Concurrently, ectopic expression of the auxin importer LIKE AUX1 and boundary gene NO APICAL MERISTEM is activated. The polarity of hairs reflects SoPIN1 patterns, suggesting that tissue cell polarity underpins oriented cell differentiation. Wing cell files reveal an anisotropic growth pattern, and computational modeling shows how polarity guiding growth can account for this pattern and wing emergence. The inverted ectopic flower orientation does not correlate with SoPIN1, suggesting that this form of regional polarity is not controlled by tissue cell polarity. Overall, the results suggest that KNOXs trigger different morphogenetic effects through interplay between tissue cell polarity, identity, and growth.

  11. Arabidopsis  SABRE and CLASP interact to stabilize cell division plane orientation and planar polarity



    The orientation of cell division and the coordination of cell polarity within the plane of the tissue layer (planar polarity) contribute to shape diverse multicellular organisms. The root of Arabidopsis thaliana displays regularly oriented cell divisions, cell elongation and planar polarity providing a plant model system to study these processes. Here we report that the SABRE protein, which shares similarity with proteins of unknown function throughout eukaryotes, has important roles in orien...

  12. Airway epithelial homeostasis and planar cell polarity signaling depend on multiciliated cell differentiation (United States)

    Vladar, Eszter K.; Nayak, Jayakar V.; Milla, Carlos E.; Axelrod, Jeffrey D.


    Motile airway cilia that propel contaminants out of the lung are oriented in a common direction by planar cell polarity (PCP) signaling, which localizes PCP protein complexes to opposite cell sides throughout the epithelium to orient cytoskeletal remodeling. In airway epithelia, PCP is determined in a 2-phase process. First, cell-cell communication via PCP complexes polarizes all cells with respect to the proximal-distal tissue axis. Second, during ciliogenesis, multiciliated cells (MCCs) undergo cytoskeletal remodeling to orient their cilia in the proximal direction. The second phase not only directs cilium polarization, but also consolidates polarization across the epithelium. Here, we demonstrate that in airway epithelia, PCP depends on MCC differentiation. PCP mutant epithelia have misaligned cilia, and also display defective barrier function and regeneration, indicating that PCP regulates multiple aspects of airway epithelial homeostasis. In humans, MCCs are often sparse in chronic inflammatory diseases, and these airways exhibit PCP dysfunction. The presence of insufficient MCCs impairs mucociliary clearance in part by disrupting PCP-driven polarization of the epithelium. Consistent with defective PCP, barrier function and regeneration are also disrupted. Pharmacological stimulation of MCC differentiation restores PCP and reverses these defects, suggesting its potential for broad therapeutic benefit in chronic inflammatory disease. PMID:27570836

  13. Planar Cell Polarity Controls Pancreatic Beta Cell Differentiation and Glucose Homeostasis

    Directory of Open Access Journals (Sweden)

    Cedric Cortijo


    Full Text Available Planar cell polarity (PCP refers to the collective orientation of cells within the epithelial plane. We show that progenitor cells forming the ducts of the embryonic pancreas express PCP proteins and exhibit an active PCP pathway. Planar polarity proteins are acquired at embryonic day 11.5 synchronously to apicobasal polarization of pancreas progenitors. Loss of function of the two PCP core components Celsr2 and Celsr3 shows that they control the differentiation of endocrine cells from polarized progenitors, with a prevalent effect on insulin-producing beta cells. This results in a decreased glucose clearance. Loss of Celsr2 and 3 leads to a reduction of Jun phosphorylation in progenitors, which, in turn, reduces beta cell differentiation from endocrine progenitors. These results highlight the importance of the PCP pathway in cell differentiation in vertebrates. In addition, they reveal that tridimensional organization and collective communication of cells are needed in the pancreatic epithelium in order to generate appropriate numbers of endocrine cells.

  14. Mechanochemical Pattern Formation in the Polarization of the One-Cell C. Elegans Embryo (United States)

    Bois, Justin S.; Grill, Stephan W.


    Cellular polarity refers to the uneven distribution of certain proteins and nucleic acids on one half of a cell versus the other. Polarity establishment is often an essential process in the development, being responsible for cell differentiation upon division of the polarized cell. The one cell embryo of the nematode Caenorhabditis elegans is a classic model system for the study of polarity. Interestingly, distribution of polarity proteins is accompanied by directional movements of the cell cytoskeleton in this system. In addition to undergoing diffusion, the polarity proteins are transported by these movements. Thus, polarization is achieved by both mechanical and chemical means. We discuss our current understanding of this process in the C. elegans model system. We also discuss more general consequences of mechanochemical coupling in morphogenesis.

  15. Differential sensitivity of epithelial cells to extracellular matrix in polarity establishment.

    Directory of Open Access Journals (Sweden)

    Shigenobu Yonemura

    Full Text Available Establishment of apical-basal polarity is crucial for epithelial sheets that form a compartment in the body, which function to maintain the environment in the compartment. Effects of impaired polarization are easily observed in three-dimensional (3-D culture systems rather than in two-dimensional (2-D culture systems. Although the mechanisms for establishing the polarity are not completely understood, signals from the extracellular matrix (ECM are considered to be essential for determining the basal side and eventually generating polarity in the epithelial cells. To elucidate the common features and differences in polarity establishment among various epithelial cells, we analyzed the formation of epithelial apical-basal polarity using three cell lines of different origin: MDCK II cells (dog renal tubules, EpH4 cells (mouse mammary gland, and R2/7 cells (human colon expressing wild-type α-catenin (R2/7 α-Cate cells. These cells showed clear apical-basal polarity in 2-D cultures. In 3-D cultures, however, each cell line displayed different responses to the same ECM. In MDCK II cells, spheroids with a single lumen formed in both Matrigel and collagen gel. In R2/7 α-Cate cells, spheroids showed similar apical-basal polarity as that seen in MDCK II cells, but had multiple lumens. In EpH4 cells, the spheroids displayed an apical-basal polarity that was opposite to that seen in the other two cell types in both ECM gels, at least during the culture period. On the other hand, the three cell lines showed the same apical-basal polarity both in 2-D cultures and in 3-D cultures using the hanging drop method. The three lines also had similar cellular responses to ECM secreted by the cells themselves. Therefore, appropriate culture conditions should be carefully determined in advance when using various epithelial cells to analyze cell polarity or 3-D morphogenesis.

  16. Differential sensitivity of epithelial cells to extracellular matrix in polarity establishment. (United States)

    Yonemura, Shigenobu


    Establishment of apical-basal polarity is crucial for epithelial sheets that form a compartment in the body, which function to maintain the environment in the compartment. Effects of impaired polarization are easily observed in three-dimensional (3-D) culture systems rather than in two-dimensional (2-D) culture systems. Although the mechanisms for establishing the polarity are not completely understood, signals from the extracellular matrix (ECM) are considered to be essential for determining the basal side and eventually generating polarity in the epithelial cells. To elucidate the common features and differences in polarity establishment among various epithelial cells, we analyzed the formation of epithelial apical-basal polarity using three cell lines of different origin: MDCK II cells (dog renal tubules), EpH4 cells (mouse mammary gland), and R2/7 cells (human colon) expressing wild-type α-catenin (R2/7 α-Cate cells). These cells showed clear apical-basal polarity in 2-D cultures. In 3-D cultures, however, each cell line displayed different responses to the same ECM. In MDCK II cells, spheroids with a single lumen formed in both Matrigel and collagen gel. In R2/7 α-Cate cells, spheroids showed similar apical-basal polarity as that seen in MDCK II cells, but had multiple lumens. In EpH4 cells, the spheroids displayed an apical-basal polarity that was opposite to that seen in the other two cell types in both ECM gels, at least during the culture period. On the other hand, the three cell lines showed the same apical-basal polarity both in 2-D cultures and in 3-D cultures using the hanging drop method. The three lines also had similar cellular responses to ECM secreted by the cells themselves. Therefore, appropriate culture conditions should be carefully determined in advance when using various epithelial cells to analyze cell polarity or 3-D morphogenesis.

  17. Mechanosensitive store-operated calcium entry regulates the formation of cell polarity. (United States)

    Huang, Yi-Wei; Chang, Shu-Jing; I-Chen Harn, Hans; Huang, Hui-Ting; Lin, Hsi-Hui; Shen, Meng-Ru; Tang, Ming-Jer; Chiu, Wen-Tai


    Ca(2+) -mediated formation of cell polarity is essential for directional migration which plays an important role in physiological and pathological processes in organisms. To examine the critical role of store-operated Ca(2+) entry, which is the major form of extracellular Ca(2+) influx in non-excitable cells, in the formation of cell polarity, we employed human bone osteosarcoma U2OS cells, which exhibit distinct morphological polarity during directional migration. Our analyses showed that Ca(2+) was concentrated at the rear end of cells and that extracellular Ca(2+) influx was important for cell polarization. Inhibition of store-operated Ca(2+) entry using specific inhibitors disrupted the formation of cell polarity in a dose-dependent manner. Moreover, the channelosomal components caveolin-1, TRPC1, and Orai1 were concentrated at the rear end of polarized cells. Knockdown of TRPC1 or a TRPC inhibitor, but not knockdown of Orai1, reduced cell polarization. Furthermore, disruption of lipid rafts or overexpression of caveolin-1 contributed to the downregulation of cell polarity. On the other hand, we also found that cell polarity, store-operated Ca(2+) entry activity, and cell stiffness were markedly decreased by low substrate rigidity, which may be caused by the disorganization of actin filaments and microtubules that occurs while regulating the activity of the mechanosensitive TRPC1 channel.

  18. VE-cadherin interacts with cell polarity protein Pals1 to regulate vascular lumen formation. (United States)

    Brinkmann, Benjamin F; Steinbacher, Tim; Hartmann, Christian; Kummer, Daniel; Pajonczyk, Denise; Mirzapourshafiyi, Fatemeh; Nakayama, Masanori; Weide, Thomas; Gerke, Volker; Ebnet, Klaus


    Blood vessel tubulogenesis requires the formation of stable cell-to-cell contacts and the establishment of apicobasal polarity of vascular endothelial cells. Cell polarity is regulated by highly conserved cell polarity protein complexes such as the Par3-aPKC-Par6 complex and the CRB3-Pals1-PATJ complex, which are expressed by many different cell types and regulate various aspects of cell polarity. Here we describe a functional interaction of VE-cadherin with the cell polarity protein Pals1. Pals1 directly interacts with VE-cadherin through a membrane-proximal motif in the cytoplasmic domain of VE-cadherin. VE-cadherin clusters Pals1 at cell-cell junctions. Mutating the Pals1-binding motif in VE-cadherin abrogates the ability of VE-cadherin to regulate apicobasal polarity and vascular lumen formation. In a similar way, deletion of the Par3-binding motif at the C-terminus of VE-cadherin impairs apicobasal polarity and vascular lumen formation. Our findings indicate that the biological activity of VE-cadherin in regulating endothelial polarity and vascular lumen formation is mediated through its interaction with the two cell polarity proteins Pals1 and Par3.

  19. Modeling Yeast Cell Polarization Induced by Pheromone Gradients (United States)

    Yi, Tau-Mu; Chen, Shanqin; Chou, Ching-Shan; Nie, Qing


    Yeast cells respond to spatial gradients of mating pheromones by polarizing and projecting up the gradient toward the source. It is thought that they employ a spatial sensing mechanism in which the cell compares the concentration of pheromone at different points on the cell surface and determines the maximum point, where the projection forms. Here we constructed the first spatial mathematical model of the yeast pheromone response that describes the dynamics of the heterotrimeric and Cdc42p G-protein cycles, which are linked in a cascade. Two key performance objectives of this system are (1) amplification—converting a shallow external gradient of ligand to a steep internal gradient of protein components and (2) tracking—following changes in gradient direction. We used simulations to investigate amplification mechanisms that allow tracking. We identified specific strategies for regulating the spatial dynamics of the protein components (i.e. their changing location in the cell) that would enable the cell to achieve both objectives.

  20. Planar cell polarity in the inner ear: how do hair cells acquire their oriented structure? (United States)

    Lewis, Julian; Davies, Alex


    Sensory hair cells in the ear and lateral line have an asymmetrical hair-bundle structure, essential for their function as directional mechanotransducers. We examine four questions: (1) how does the planar asymmetry of the individual hair cell originate? (2) How are the orientations of neighboring hair cells coordinated? (3) How is the orientation of a group of hair cells controlled in relation to the ear as a whole? (4) How does the initial cell asymmetry lead to creation of the asymmetrical hair bundle? Studies of the development of hairs and bristles in Drosophila, combined with genetic data from vertebrates, suggest that the answer to questions (1) and (2) lies in asymmetries that develop at the cell cortex and at cell-cell junctions, generated by products of a set of primary planar cell polarity genes, including the transmembrane receptor Frizzled. A separate and largely independent mechanism controls asymmmetric allocation of cell fate determinants such as Numb at mitosis, in Drosophila and possibly in the ear also. Little is known about long-range signals that might orient hair cells globally in the ear, but progress has been made in identifying a set of genes responsible for read-out of the primary polarity specification. These genes, in flies and vertebrates, provide a link to assembly of the polarized cytoskeleton; myosin VIIA appears to belong in this group. The mechanism creating the staircase pattern of stereocilium lengths is unknown, but could involve regulation of stereocilium growth by Ca(2+) ions entering via transduction channels.

  1. Planar cell polarity signalling couples cell division and morphogenesis during neurulation. (United States)

    Ciruna, Brian; Jenny, Andreas; Lee, Diana; Mlodzik, Marek; Schier, Alexander F


    Environmental and genetic aberrations lead to neural tube closure defects (NTDs) in 1 out of every 1,000 births. Mouse and frog models for these birth defects have indicated that Van Gogh-like 2 (Vangl2, also known as Strabismus) and other components of planar cell polarity (PCP) signalling might control neurulation by promoting the convergence of neural progenitors to the midline. Here we show a novel role for PCP signalling during neurulation in zebrafish. We demonstrate that non-canonical Wnt/PCP signalling polarizes neural progenitors along the anteroposterior axis. This polarity is transiently lost during cell division in the neural keel but is re-established as daughter cells reintegrate into the neuroepithelium. Loss of zebrafish Vangl2 (in trilobite mutants) abolishes the polarization of neural keel cells, disrupts re-intercalation of daughter cells into the neuroepithelium, and results in ectopic neural progenitor accumulations and NTDs. Remarkably, blocking cell division leads to rescue of trilobite neural tube morphogenesis despite persistent defects in convergence and extension. These results reveal a function for PCP signalling in coupling cell division and morphogenesis at neurulation and indicate a previously unrecognized mechanism that might underlie NTDs.

  2. Establishing and maintaining cell polarity with mRNA localization in Drosophila. (United States)

    Barr, Justinn; Yakovlev, Konstantin V; Shidlovskii, Yulii; Schedl, Paul


    How cell polarity is established and maintained is an important question in diverse biological contexts. Molecular mechanisms used to localize polarity proteins to distinct domains are likely context-dependent and provide a feedback loop in order to maintain polarity. One such mechanism is the localized translation of mRNAs encoding polarity proteins, which will be the focus of this review and may play a more important role in the establishment and maintenance of polarity than is currently known. Localized translation of mRNAs encoding polarity proteins can be used to establish polarity in response to an external signal, and to maintain polarity by local production of polarity determinants. The importance of this mechanism is illustrated by recent findings, including orb2-dependent localized translation of aPKC mRNA at the apical end of elongating spermatid tails in the Drosophila testis, and the apical localization of stardust A mRNA in Drosophila follicle and embryonic epithelia.

  3. Epithelial cell polarity and tumorigenesis: new perspectives for cancer detection and treatment

    Institute of Scientific and Technical Information of China (English)

    Danila CORADINI; Claudia CASARSA; Saro ORIANA


    Loss of cell-cell adhesion and cell polarity is commonly observed in tumors of epithelial origin and correlates with their invasion into adjacent tissues and formation of metastases. Growing evidence indicates that loss of cell polarity and cell-cell adhesion may also be important in early stage of cancer. In first part of this review, we delineate the current understanding of the mechanisms that establish and maintain the polarity of epithelial tissues and discuss the involvement of cell polarity and apical junctional complex components in tumor pathogenesis. In the second part we address the clinical significance of cell polarity and junctional complex components in can- cer diagnosis and prognosis. Finally, we explore their potential use as therapeutic targets in the treatment of cancer.

  4. Cytoskeletal dynamics and cell signaling during planar polarity establishment in the Drosophila embryonic denticle. (United States)

    Price, Meredith H; Roberts, David M; McCartney, Brooke M; Jezuit, Erin; Peifer, Mark


    Many epithelial cells are polarized along the plane of the epithelium, a property termed planar cell polarity. The Drosophila wing and eye imaginal discs are the premier models of this process. Many proteins required for polarity establishment and its translation into cytoskeletal polarity were identified from studies of those tissues. More recently, several vertebrate tissues have been shown to exhibit planar cell polarity. Striking similarities and differences have been observed when different tissues exhibiting planar cell polarity are compared. Here we describe a new tissue exhibiting planar cell polarity - the denticles, hair-like projections of the Drosophila embryonic epidermis. We describe in real time the changes in the actin cytoskeleton that underlie denticle development, and compare this with the localization of microtubules, revealing new aspects of cytoskeletal dynamics that may have more general applicability. We present an initial characterization of the localization of several actin regulators during denticle development. We find that several core planar cell polarity proteins are asymmetrically localized during the process. Finally, we define roles for the canonical Wingless and Hedgehog pathways and for core planar cell polarity proteins in denticle polarity.

  5. New machinery is required for fuel cells. Mechanical engineering must keep in pace with the trend; Wer Brennstoffzellen will, braucht andere Maschinen. Maschinenbau darf Entwicklung nicht verpassen

    Energy Technology Data Exchange (ETDEWEB)



    Nobody knows whether fuel cells will have had their breakthrough by 2010. In view of the consequences for mechanical engineering, however, producers should keep abreast of developments. [German] Ob sich die Brennstoffzelle bis 2010 etabliert, kann noch niemand sicher sagen. Wegen der Folgen fuer den Maschinenbau sollten sich die Unternehmen jedoch mit dieser Moeglichkeit rechtzeitig befassen. (orig.)

  6. Transient Tissue-Scale Deformation Coordinates Alignment of Planar Cell Polarity Junctions in the Mammalian Skin. (United States)

    Aw, Wen Yih; Heck, Bryan W; Joyce, Bradley; Devenport, Danelle


    Planar cell polarity (PCP) refers to the collective alignment of polarity along the tissue plane. In skin, the largest mammalian organ, PCP aligns over extremely long distances, but the global cues that orient tissue polarity are unknown. Here, we show that Celsr1 asymmetry arises concomitant with a gradient of tissue deformation oriented along the medial-lateral axis. This uniaxial tissue tension, whose origin remains unknown, transiently transforms basal epithelial cells from initially isotropic and disordered states into highly elongated and aligned morphologies. Reorienting tissue deformation is sufficient to shift the global axis of polarity, suggesting that uniaxial tissue strain can act as a long-range polarizing cue. Observations both in vivo and in vitro suggest that the effect of tissue anisotropy on Celsr1 polarity is not a direct consequence of cell shape but rather reflects the restructuring of cell-cell interfaces during oriented cell divisions and cell rearrangements that serve to relax tissue strain. We demonstrate that cell intercalations remodel intercellular junctions predominantly between the mediolateral interfaces of neighboring cells. This restructuring of the cell surface polarizes Celsr1, which is slow to accumulate at nascent junctions yet stably associates with persistent junctions. We propose that tissue anisotropy globally aligns Celsr1 polarity by creating a directional bias in the formation of new cell interfaces while simultaneously aligning the persistent interfaces at which Celsr1 prefers to accumulate.

  7. Acquisition of cell polarity during cell cycle and oral replacement in Tetrahymena. (United States)

    Kaczanowska, Janina; Kaczanowski, Szymon; Kiersnowska, Mauryla; Fabczak, Hanna; Tulodziecka, Karolina; Kaczanowski, Andrzej


    The aim of this study was to search for a mechanism responsible for the acquisition of cell polarity in a ciliate Tetrahymena. Homologs of the mammalian genes coding for CDC42-GSK3beta- MARK/PAR1-MAPs proteins were found in the Tetrahymena genome (Eisen et al., 2006, and this study). These proteins belong to a pathway which controls assembly and disassembly of microtubule bundles and cell polarity in neural cells. In Tetrahymena, there are two types of morphogenesis: divisional and oral replacement (OR). In divisional morphogenesis, an elongation of longitudinal microtubule bundles (LMs) takes place during cell division. In contrast, in OR type morphogenesis, which occurs in starved non-dividing cells, a polar retraction of LMs occurs. In T. pyriformis, the frequency of developmental switch to OR morphogenesis increases in the presence of wortmannin, an inhibitor of the CDC42-GSK3beta-MARK pathway. In contrast, wortmannin when applied to dividing cells does not affect divisional morphogenesis. Using immunostaining with the antibody against mammalian mitotic phosphoproteins (MPM-2) we show that these proteins co-localize with the LMs and are distributed along the anterior-posterior gradient. In addition, we show that during OR type morphogenesis, the fate of LMs correlates with the anterior-posterior gradient of instability of the cortical structures. We used the conditional mouth-less mutant of T. thermophila (Tiedtke et al., 1988) to test if the presence of the oral apparatus is required for the maintenance of cell polarity. We discuss our results in relation to the hypothesis of GSK3-beta-MARK pathway involvement in the acquisition of cell polarity in Tetrahymena.

  8. Self-organization and advective transport in the cell polarity formation for asymmetric cell division. (United States)

    Seirin Lee, Sungrim; Shibata, Tatsuo


    Anterior-Posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which depends not only on the several genetic process but also biochemical and biophysical interactions. The mechanism of AP formation of Caenorhabditis elegans embryo is characterized into the three processes: (i) membrane association and dissociation of posterior and anterior proteins, (ii) diffusion into the membrane and cytosol, and (iii) active cortical and cytoplasmic flows induced by the contraction of the acto-myosin cortex. We explored the mechanism of symmetry breaking and AP polarity formation using self-recruitment model of posterior proteins. We found that the AP polarity pattern is established over wide range in the total mass of polarity proteins and the diffusion ratio in the cytosol to the membrane. We also showed that the advective transport in both membrane and cytosol during the establishment phase affects optimal time interval of establishment and positioning of the posterior domain, and plays a role to increase the robustness in the AP polarity formation by reducing the number of posterior domains for the sensitivity of initial conditions. We also demonstrated that a proper ratio of the total mass to cell size robustly regulate the length scale of the posterior domain.

  9. Keeping Your Voice Healthy (United States)

    ... Find an ENT Doctor Near You Keeping Your Voice Healthy Keeping Your Voice Healthy Patient Health Information ... heavily voice-related. Key Steps for Keeping Your Voice Healthy Drink plenty of water. Moisture is good ...

  10. Functional genomics in the study of yeast cell polarity: moving in the right direction. (United States)

    Styles, Erin; Youn, Ji-Young; Mattiazzi Usaj, Mojca; Andrews, Brenda


    The budding yeast Saccharomyces cerevisiae has been used extensively for the study of cell polarity, owing to both its experimental tractability and the high conservation of cell polarity and other basic biological processes among eukaryotes. The budding yeast has also served as a pioneer model organism for virtually all genome-scale approaches, including functional genomics, which aims to define gene function and biological pathways systematically through the analysis of high-throughput experimental data. Here, we outline the contributions of functional genomics and high-throughput methodologies to the study of cell polarity in the budding yeast. We integrate data from published genetic screens that use a variety of functional genomics approaches to query different aspects of polarity. Our integrated dataset is enriched for polarity processes, as well as some processes that are not intrinsically linked to cell polarity, and may provide new areas for future study.

  11. Superresolution microscopy reveals a dynamic picture of cell polarity maintenance during directional growth. (United States)

    Ishitsuka, Yuji; Savage, Natasha; Li, Yiming; Bergs, Anna; Grün, Nathalie; Kohler, Daria; Donnelly, Rebecca; Nienhaus, G Ulrich; Fischer, Reinhard; Takeshita, Norio


    Polar (directional) cell growth, a key cellular mechanism shared among a wide range of species, relies on targeted insertion of new material at specific locations of the plasma membrane. How these cell polarity sites are stably maintained during massive membrane insertion has remained elusive. Conventional live-cell optical microscopy fails to visualize polarity site formation in the crowded cell membrane environment because of its limited resolution. We have used advanced live-cell imaging techniques to directly observe the localization, assembly, and disassembly processes of cell polarity sites with high spatiotemporal resolution in a rapidly growing filamentous fungus, Aspergillus nidulans. We show that the membrane-associated polarity site marker TeaR is transported on microtubules along with secretory vesicles and forms a protein cluster at that point of the apical membrane where the plus end of the microtubule touches. There, a small patch of membrane is added through exocytosis, and the TeaR cluster gets quickly dispersed over the membrane. There is an incessant disassembly and reassembly of polarity sites at the growth zone, and each new polarity site locus is slightly offset from preceding ones. On the basis of our imaging results and computational modeling, we propose a transient polarity model that explains how cell polarity is stably maintained during highly active directional growth.

  12. Lethal (2) giant larvae: an indispensable regulator of cell polarity and cancer development. (United States)

    Cao, Fang; Miao, Yi; Xu, Kedong; Liu, Peijun


    Cell polarity is one of the most basic properties of all normal cells and is essential for regulating numerous biological processes. Loss of polarity is considered a hallmark for cancer. Multiple polarity proteins are implicated in maintenance of cell polarity. Lethal (2) giant larvae (Lgl) is one of polarity proteins that plays an important role in regulating cell polarity, asymmetric division as well as tumorigenesis. Lgl proteins in different species have similar structures and conserved functions. Lgl acts as an indispensable regulator of cell biological function, including cell polarity and asymmetric division, through interplaying with other polarity proteins, regulating exocytosis, mediating cytoskeleton and being involved in signaling pathways. Furthermore, Lgl plays a role of a tumor suppressor, and the aberrant expression of Hugl, a human homologue of Lgl, contributes to multiple cancers. However, the exact functions of Lgl and the underlying mechanisms remain enigmatic. In this review, we will give an overview of the Lgl functions in cell polarity and cancer development, discuss the potential mechanisms underlying these functions, and raise our conclusion of previous studies and points of view about the future studies.

  13. Mechanistic Framework for Establishment, Maintenance, and Alteration of Cell Polarity in Plants

    Directory of Open Access Journals (Sweden)

    Pankaj Dhonukshe


    Full Text Available Cell polarity establishment, maintenance, and alteration are central to the developmental and response programs of nearly all organisms and are often implicated in abnormalities ranging from patterning defects to cancer. By residing at the distinct plasma membrane domains polar cargoes mark the identities of those domains, and execute localized functions. Polar cargoes are recruited to the specialized membrane domains by directional secretion and/or directional endocytic recycling. In plants, auxin efflux carrier PIN proteins display polar localizations in various cell types and play major roles in directional cell-to-cell transport of signaling molecule auxin that is vital for plant patterning and response programs. Recent advanced microscopy studies applied to single cells in intact plants reveal subcellular PIN dynamics. They uncover the PIN polarity generation mechanism and identified important roles of AGC kinases for polar PIN localization. AGC kinase family members PINOID, WAG1, and WAG2, belonging to the AGC-3 subclass predominantly influence the polar localization of PINs. The emerging mechanism for AGC-3 kinases action suggests that kinases phosphorylate PINs mainly at the plasma membrane after initial symmetric PIN secretion for eventual PIN internalization and PIN sorting into distinct ARF-GEF-regulated polar recycling pathways. Thus phosphorylation status directs PIN translocation to different cell sides. Based on these findings a mechanistic framework evolves that suggests existence of cell side-specific recycling pathways in plants and implicates AGC3 kinases for differential PIN recruitment among them for eventual PIN polarity establishment, maintenance, and alteration.

  14. Regulation of cell polarity determinants by the Retinoblastoma tumor suppressor protein



    In addition to their canonical roles in the cell cycle, RB family proteins regulate numerous developmental pathways, although the mechanisms remain obscure. We found that Drosophila Rbf1 associates with genes encoding components of the highly conserved apical–basal and planar cell polarity pathways, suggesting a possible regulatory role. Here, we show that depletion of Rbf1 in Drosophila tissues is indeed associated with polarity defects in the wing and eye. Key polarity genes aPKC, par6, van...

  15. Planar cell polarity-mediated induction of neural stem cell expansion during axolotl spinal cord regeneration. (United States)

    Rodrigo Albors, Aida; Tazaki, Akira; Rost, Fabian; Nowoshilow, Sergej; Chara, Osvaldo; Tanaka, Elly M


    Axolotls are uniquely able to mobilize neural stem cells to regenerate all missing regions of the spinal cord. How a neural stem cell under homeostasis converts after injury to a highly regenerative cell remains unknown. Here, we show that during regeneration, axolotl neural stem cells repress neurogenic genes and reactivate a transcriptional program similar to embryonic neuroepithelial cells. This dedifferentiation includes the acquisition of rapid cell cycles, the switch from neurogenic to proliferative divisions, and the re-expression of planar cell polarity (PCP) pathway components. We show that PCP induction is essential to reorient mitotic spindles along the anterior-posterior axis of elongation, and orthogonal to the cell apical-basal axis. Disruption of this property results in premature neurogenesis and halts regeneration. Our findings reveal a key role for PCP in coordinating the morphogenesis of spinal cord outgrowth with the switch from a homeostatic to a regenerative stem cell that restores missing tissue.

  16. Tissue-wide Mechanical Forces Influence the Polarity of Stomatal Stem Cells in Arabidopsis. (United States)

    Bringmann, Martin; Bergmann, Dominique C


    Mechanical information is an important contributor to cell polarity in uni- and multicellular systems [1-3]. In planar tissues like the Drosophila wing, cell polarity reorients during growth as cells divide and reorganize [4]. In another planar tissue, the Arabidopsis leaf epidermis [5], polarized, asymmetric divisions of stomatal stem cells (meristemoid mother cells [MMCs]) are fundamental for the generation and patterning of multiple cell types, including stomata. The activity of key transcription factors, polarizing factors [6], and peptide signals [7] explains some local stomatal patterns emerging from the behavior of a few lineally related cells [6, 8-11]. Here we demonstrate that, in addition to locally acting signals, tissue-wide mechanical forces can act as organizing cues, and that they do so by influencing the polarity of individual MMCs. If the mechanical stress environment in the tissue is altered through stretching or cell ablations, cellular polarity changes in response. In turn, polarity predicts the orientation of cellular and tissue outgrowth, leading to increased mechanical conflicts between neighboring cells. This interplay among growth, oriented divisions, and cell specification could contribute to the characteristic patterning of stomatal guard cells in the context of a growing leaf.

  17. The cadherin Fat2 is required for planar cell polarity in the Drosophila ovary. (United States)

    Viktorinová, Ivana; König, Tina; Schlichting, Karin; Dahmann, Christian


    Planar cell polarity is an important characteristic of many epithelia. In the Drosophila wing, eye and abdomen, establishment of planar cell polarity requires the core planar cell polarity genes and two cadherins, Fat and Dachsous. Drosophila Fat2 is a cadherin related to Fat; however, its role during planar cell polarity has not been studied. Here, we have generated mutations in fat2 and show that Fat2 is required for the planar polarity of actin filament orientation at the basal side of ovarian follicle cells. Defects in actin filament orientation correlate with a failure of egg chambers to elongate during oogenesis. Using a functional fosmid-based fat2-GFP transgene, we show that the distribution of Fat2 protein in follicle cells is planar polarized and that Fat2 localizes where basal actin filaments terminate. Mosaic analysis demonstrates that Fat2 acts non-autonomously in follicle cells, indicating that Fat2 is required for the transmission of polarity information. Our results suggest a principal role for Fat-like cadherins during the establishment of planar cell polarity.

  18. Temporal regulation of planar cell polarity: insights from the Drosophila eye. (United States)

    Schweisguth, François


    In this issue of Cell, identify a first regulatory link between planar cell polarity (PCP) signaling and apical-basal polarity. The authors propose that a component of the apical Crumbs complex regulates the phosphorylation of the Frizzled (Fz) PCP receptor, thus modulating PCP in the Drosophila eye.

  19. Phenotype and polarization of autologous T cells by biomaterial-treated dendritic cells. (United States)

    Park, Jaehyung; Gerber, Michael H; Babensee, Julia E


    Given the central role of dendritic cells (DCs) in directing T-cell phenotypes, the ability of biomaterial-treated DCs to dictate autologous T-cell phenotype was investigated. In this study, we demonstrate that differentially biomaterial-treated DCs differentially directed autologous T-cell phenotype and polarization, depending on the biomaterial used to pretreat the DCs. Immature DCs (iDCs) were derived from human peripheral blood monocytes and treated with biomaterial films of alginate, agarose, chitosan, hyaluronic acid, or 75:25 poly(lactic-co-glycolic acid) (PLGA), followed by co-culture of these biomaterial-treated DCs and autologous T cells. When autologous T cells were co-cultured with DCs treated with biomaterial film/antigen (ovalbumin, OVA) combinations, different biomaterial films induced differential levels of T-cell marker (CD4, CD8, CD25, CD69) expression, as well as differential cytokine profiles [interferon (IFN)-γ, interleukin (IL)-12p70, IL-10, IL-4] in the polarization of T helper (Th) types. Dendritic cells treated with agarose films/OVA induced CD4+CD25+FoxP3+ (T regulatory cells) expression, comparable to untreated iDCs, on autologous T cells in the DC-T co-culture system. Furthermore, in this co-culture, agarose treatment induced release of IL-12p70 and IL-10 at higher levels as compared with DC treatment with other biomaterial films/OVA, suggesting Th1 and Th2 polarization, respectively. Dendritic cells treated with PLGA film/OVA treatment induced release of IFN-γ at higher levels compared with that observed for co-cultures with iDCs or DCs treated with all other biomaterial films. These results indicate that DC treatment with different biomaterial films has potential as a tool for immunomodulation by directing autologous T-cell responses.

  20. Prkci is required for a non-autonomous signal that coordinates cell polarity during cavitation. (United States)

    Mah, In Kyoung; Soloff, Rachel; Izuhara, Audrey K; Lakeland, Daniel L; Wang, Charles; Mariani, Francesca V


    Polarized epithelia define boundaries, spaces, and cavities within organisms. Cavitation, a process by which multicellular hollow balls or tubes are produced, is typically associated with the formation of organized epithelia. In order for these epithelial layers to form, cells must ultimately establish a distinct apical-basal polarity. Atypical PKCs have been proposed to be required for apical-basal polarity in diverse species. Here we show that while cells null for the Prkci isozyme exhibit some polarity characteristics, they fail to properly segregate apical-basal proteins, form a coordinated ectodermal epithelium, or participate in normal cavitation. A failure to cavitate could be due to an overgrowth of interior cells or to an inability of interior cells to die. Null cells however, do not have a marked change in proliferation rate and are still capable of undergoing cell death, suggesting that alterations in these processes are not the predominant cause of the failed cavitation. Overexpression of BMP4 or EZRIN can partially rescue the phenotype possibly by promoting cell death, polarity, and differentiation. However, neither is sufficient to provide the required cues to generate a polarized epithelium and fully rescue cavitation. Interestingly, when wildtype and Prkci(-/-) ES cells are mixed together, a polarized ectodermal epithelium forms and cavitation is rescued, likely due to the ability of wildtype cells to produce non-autonomous polarity cues. We conclude that Prkci is not required for cells to respond to these cues, though it is required to produce them. Together these findings indicate that environmental cues can facilitate the formation of polarized epithelia and that cavitation requires the proper coordination of multiple basic cellular processes including proliferation, differentiation, cell death, and apical-basal polarization.

  1. Positioning of polarity formation by extracellular signaling during asymmetric cell division. (United States)

    Seirin Lee, Sungrim


    Anterior-posterior (AP) polarity formation of cell membrane proteins plays a crucial role in determining cell asymmetry, which ultimately generates cell diversity. In Caenorhabditis elegans, a single fertilized egg cell (P0), its daughter cell (P1), and the germline precursors (P2 and P3 cells) form two exclusive domains of different PAR proteins on the membrane along the anterior-posterior axis. However, the phenomenon of polarity reversal has been observed in which the axis of asymmetric cell division of the P2 and P3 cells is formed in an opposite manner to that of the P0 and P1 cells. The extracellular signal MES-1/SRC-1 has been shown to induce polarity reversal, but the detailed mechanism remains elusive. Here, using a mathematical model, I explore the mechanism by which MES-1/SRC-1 signaling can induce polarity reversal and ultimately affect the process of polarity formation. I show that a positive correlation between SRC-1 and the on-rate of PAR-2 is the essential mechanism underlying polarity reversal, providing a mathematical basis for the orientation of cell polarity patterns.

  2. Loss of Cell Adhesion Increases Tumorigenic Potential of Polarity Deficient Scribble Mutant Cells.

    Directory of Open Access Journals (Sweden)

    Indrayani Waghmare

    Full Text Available Epithelial polarity genes are important for maintaining tissue architecture, and regulating growth. The Drosophila neoplastic tumor suppressor gene scribble (scrib belongs to the basolateral polarity complex. Loss of scrib results in disruption of its growth regulatory functions, and downregulation or mislocalization of Scrib is correlated to tumor growth. Somatic scribble mutant cells (scrib- surrounded by wild-type cells undergo apoptosis, which can be prevented by introduction of secondary mutations that provide a growth advantage. Using genetic tools in Drosophila, we analyzed the phenotypic effects of loss of scrib in different growth promoting backgrounds. We investigated if a central mechanism that regulates cell adhesion governs the growth and invasive potential of scrib mutant cells. Here we show that increased proliferation, and survival abilities of scrib- cells in different genetic backgrounds affect their differentiation, and intercellular adhesion. Further, loss of scrib is sufficient to cause reduced cell survival, activation of the JNK pathway and a mild reduction of cell adhesion. Our data show that for scrib cells to induce aggressive tumor growth characterized by loss of differentiation, cell adhesion, increased proliferation and invasion, cooperative interactions that derail signaling pathways play an essential role in the mechanisms leading to tumorigenesis. Thus, our study provides new insights on the effects of loss of scrib and the modification of these effects via cooperative interactions that enhance the overall tumorigenic potential of scrib deficient cells.

  3. Neurotypic cell attachment and growth on III-nitride lateral polarity structures. (United States)

    Bain, L E; Kirste, R; Johnson, C A; Ghashghaei, H T; Collazo, R; Ivanisevic, A


    III-nitride materials have recently received increasing levels of attention for their potential to successfully interface with, and sense biochemical interactions in biological systems. Expanding on available sensing schemes (including transistor-based devices,) a III-N lateral polarity structure capable of introducing quasi-phase matching through a periodic polarity grating presents a novel platform for second harmonic generation. This platform constitutes a non-linear optical phenomenon with exquisite sensitivity to the chemical state of a surface or interface. To characterize the response of a biological system to the nanostructured lateral polarity structures, we cultured neurotypic PC12 cells on AlGaN with varying ratios of Al:Ga - 0, 0.4, 0.6, and 1 - and on surfaces of varying pitch to the III-polar vs. N-polar grating - 5, 10, 20 and 50 μm. While some toxicity associated with increasing Al is observed, we documented and quantified trends in cell responses to the local material polarity and nanoscale roughness. The nitrogen-polar material has a significantly higher nanoscale roughness than III-polar regions, and a 80-200 nm step height difference between the III-polar and N-polar materials in the lateral polarity configuration generates adequate changes in topography to influence cell growth, improves cell adhesion and promotes cell migration along the direction of the features. As the designed material configuration is further explored for biochemical sensing, the lateral polarity scheme may provide a route in assessing the non-specific protein adsorption to this varying nano-topography that drives the subsequent cell response.

  4. Pak3 regulates apical-basal polarity in migrating border cells during Drosophila oogenesis. (United States)

    Felix, Martina; Chayengia, Mrinal; Ghosh, Ritabrata; Sharma, Aditi; Prasad, Mohit


    Group cell migration is a highly coordinated process that is involved in a number of physiological events such as morphogenesis, wound healing and tumor metastasis. Unlike single cells, collectively moving cells are physically attached to each other and retain some degree of apical-basal polarity during the migratory phase. Although much is known about direction sensing, how polarity is regulated in multicellular movement remains unclear. Here we report the role of the protein kinase Pak3 in maintaining apical-basal polarity in migrating border cell clusters during Drosophila oogenesis. Pak3 is enriched in border cells and downregulation of its function impedes border cell movement. Time-lapse imaging suggests that Pak3 affects protrusive behavior of the border cell cluster, specifically regulating the stability and directionality of protrusions. Pak3 functions downstream of guidance receptor signaling to regulate the level and distribution of F-actin in migrating border cells. We also provide evidence that Pak3 genetically interacts with the lateral polarity marker Scribble and that it regulates JNK signaling in the moving border cells. Since Pak3 depletion results in mislocalization of several apical-basal polarity markers and overexpression of Jra rescues the polarity of the Pak3-depleted cluster, we propose that Pak3 functions through JNK signaling to modulate apical-basal polarity of the migrating border cell cluster. We also observe loss of apical-basal polarity in Rac1-depleted border cell clusters, suggesting that guidance receptor signaling functions through Rac GTPase and Pak3 to regulate the overall polarity of the cluster and mediate efficient collective movement of the border cells to the oocyte boundary.

  5. Phosphorylation of the Polarity Protein BASL Differentiates Asymmetric Cell Fate through MAPKs and SPCH. (United States)

    Zhang, Ying; Guo, Xiaoyu; Dong, Juan


    Cell polarization is commonly used for the regulation of stem cell asymmetric division in both animals and plants. Stomatal development in Arabidopsis, a process that produces breathing pores in the epidermis, requires asymmetric cell division to differentiate highly specialized guard cells while maintaining a stem cell population [1, 2]. The BREAKING OF ASYMMETRY IN THE STOMATAL LINEAGE (BASL) protein exhibits a polarized localization pattern in the cell and is required for differential cell fates resulting from asymmetric cell division [3]. The polarization of BASL is made possible by a positive feedback loop with a canonical mitogen-activated protein kinase (MAPK) pathway that recruits the MAPKK kinase YODA (YDA) and MAPK 6 (MPK6) to the cortical polarity site [4]. Here, we study BASL intracellular dynamics and show that the membrane-associated BASL is slowly replenished at the cortical polarity site and that the mobility is tightly linked to its phosphorylation status. Because BASL polarity is only exhibited by one daughter cell after an asymmetric cell division, we study how BASL differentially functions in the two daughter cells. The YDA MAPK cascade transduces upstream ligand-receptor signaling [5-13] to the transcription factor SPEECHLESS (SPCH), which controls stomatal initiation and is directly suppressed by MPK3/6-mediated phosphorylation [14, 15]. We show that BASL polarization leads to elevated nuclear MPK6 signaling and lowered SPCH abundance in one of the two daughter cells. Therefore, two daughter cells are differentiated by BASL polarity-mediated differential suppression of SPCH, which may provide developmental plasticity in plant stem cell asymmetric cell division (ACD).

  6. Spatial and temporal aspects of Wnt signaling and planar cell polarity during vertebrate embryonic development. (United States)

    Sokol, Sergei Y


    Wnt signaling pathways act at multiple locations and developmental stages to specify cell fate and polarity in vertebrate embryos. A long-standing question is how the same molecular machinery can be reused to produce different outcomes. The canonical Wnt/β-catenin branch modulates target gene transcription to specify cell fates along the dorsoventral and anteroposterior embryonic axes. By contrast, the Wnt/planar cell polarity (PCP) branch is responsible for cell polarization along main body axes, which coordinates morphogenetic cell behaviors during gastrulation and neurulation. Whereas both cell fate and cell polarity are modulated by spatially- and temporally-restricted Wnt activity, the downstream signaling mechanisms are very diverse. This review highlights recent progress in the understanding of Wnt-dependent molecular events leading to the establishment of PCP and linking it to early morphogenetic processes.

  7. Wnt and planar cell polarity signaling in cystic renal disease. (United States)

    Goggolidou, Paraskevi


    Cystic kidney diseases can cause end stage renal disease, affecting millions of individuals worldwide. They may arise early or later in life, are characterized by a spectrum of symptoms and can be caused by diverse genetic defects. The primary cilium, a microtubule-based organelle that can serve as a signaling antenna, has been demonstrated to have a significant role in ensuring correct kidney development and function. In the kidney, one of the signaling pathways that requires the cilium for normal development is Wnt signaling. In this review, the roles of primary cilia in relation to canonical and non-canonical Wnt/PCP signaling in cystic renal disease are described. The evidence of the associations between cilia, Wnt signaling and cystic renal disease is discussed and the significance of planar cell polarity-related mechanisms in cystic kidney disease is presented. Although defective Wnt signaling is not the only cause of renal disease, research is increasingly highlighting its importance, encouraging the development of Wnt-associated diagnostic and prognostic tools for cystic renal disease.

  8. Flotillins are involved in the polarization of primitive and mature hematopoietic cells.

    Directory of Open Access Journals (Sweden)

    Lawrence Rajendran

    Full Text Available BACKGROUND: Migration of mature and immature leukocytes in response to chemokines is not only essential during inflammation and host defense, but also during development of the hematopoietic system. Many molecules implicated in migratory polarity show uniform cellular distribution under non-activated conditions, but acquire a polarized localization upon exposure to migratory cues. METHODOLOGY/PRINCIPAL FINDINGS: Here, we present evidence that raft-associated endocytic proteins (flotillins are pre-assembled in lymphoid, myeloid and primitive hematopoietic cells and accumulate in the uropod during migration. Furthermore, flotillins display a polarized distribution during immunological synapse formation. Employing the membrane lipid-order sensitive probe Laurdan, we show that flotillin accumulation in the immunological synapse is concomittant with membrane ordering in these regions. CONCLUSIONS: Together with the observation that flotillin polarization does not occur in other polarized cell types such as polarized epithelial cells, our results suggest a specific role for flotillins in hematopoietic cell polarization. Based on our results, we propose that in hematopoietic cells, flotillins provide intrinsic cues that govern segregation of certain microdomain-associated molecules during immune cell polarization.

  9. Rules of chemokine receptor association with T cell polarization in vivo



    Current concepts of chemokine receptor (CKR) association with Th1 and Th2 cell polarization and effector function have largely ignored the diverse nature of effector and memory T cells in vivo. Here, we systematically investigated the association of 11 CKRs, singly or in combination, with CD4 T cell polarization. We show that Th1, Th2, Th0, and nonpolarized T cells in blood and tissue can express any of the CKRs studied but that each CKR defines a characteristic pool of polarized and nonpolar...

  10. A three-tiered mechanism for regulation of planar cell polarity. (United States)

    Tree, David R P; Ma, Dali; Axelrod, Jeffrey D


    Some epithelial cells are polarized along an axis orthogonal to their apical-basal axes. Recent studies in Drosophila lead to the view that three classes of signaling molecules govern the planar cell polarity (PCP) pathway. The first class, or module, functions across whole tissues, providing directional information to individual cells. The second module, apparently shared by all planar polarized tissues, and related to the canonical Wnt signaling pathway, interprets the directional signal to produce subcellular asymmetries. The third modules are tissue specific, acting to translate subcellular asymmetry into the appropriate morphological manifestations in the different cell types.

  11. Plasticity of both planar cell polarity and cell identity during the development of Drosophila. (United States)

    Saavedra, Pedro; Vincent, Jean-Paul; Palacios, Isabel M; Lawrence, Peter A; Casal, José


    Drosophila has helped us understand the genetic mechanisms of pattern formation. Particularly useful have been those organs in which different cell identities and polarities are displayed cell by cell in the cuticle and epidermis (Lawrence, 1992; Bejsovec and Wieschaus, 1993; Freeman, 1997). Here we use the pattern of larval denticles and muscle attachments and ask how this pattern is maintained and renewed over the larval moult cycles. During larval growth each epidermal cell increases manyfold in size but neither divides nor dies. We follow individuals from moult to moult, tracking marked cells and find that, as cells are repositioned and alter their neighbours, their identities change to compensate and the pattern is conserved. Single cells adopting a new fate may even acquire a new polarity: an identified cell that makes a forward-pointing denticle in the first larval stage may make a backward-pointing denticle in the second and third larval stages. DOI:

  12. Wdr1-mediated cell shape dynamics and cortical tension are essential for epidermal planar cell polarity. (United States)

    Luxenburg, Chen; Heller, Evan; Pasolli, H Amalia; Chai, Sophia; Nikolova, Maria; Stokes, Nicole; Fuchs, Elaine


    During mouse development, core planar cell polarity (PCP) proteins become polarized in the epidermal plane to guide angling/morphogenesis of hair follicles. How PCP is established is poorly understood. Here, we identify a key role for Wdr1 (also known as Aip1), an F-actin-binding protein that enhances cofilin/destrin-mediated F-actin disassembly. We show that cofilin and destrin function redundantly in developing epidermis, but their combined depletion perturbs cell adhesion, cytokinesis, apicobasal polarity and PCP. Although Wdr1 depletion accentuates single-loss-of-cofilin/destrin phenotypes, alone it resembles core PCP mutations. Seeking a mechanism, we find that Wdr1 and cofilin/destrin-mediated actomyosin remodelling are essential for generating or maintaining cortical tension within the developing epidermal sheet and driving the cell shape and planar orientation changes that accompany establishment of PCP in mammalian epidermis. Our findings suggest intriguing evolutionary parallels but mechanistic modifications to the distal wing hinge-mediated mechanical forces that drive cell shape change and orient PCP in the Drosophila wing disc.

  13. Electrical signals polarize neuronal organelles, direct neuron migration, and orient cell division. (United States)

    Yao, Li; McCaig, Colin D; Zhao, Min


    During early brain development, the axis of division of neuronal precursor cells is regulated tightly and can determine whether neurons remain in the germinal layers or migrate away. Directed neuronal migration depends on the establishment of cell polarity, and cells are polarized dynamically in response to extracellular signals. Endogenous electric fields (EFs) orient cell division and direct migration of a variety of cell types. Here, we show that cell division of cultured hippocampal cells (neuron-like cells and glial-like cells) is oriented strikingly by an applied EF, which also directs neuronal migration. Directed migration involves polarization of the leading neurite, of the microtubule-associated protein MAP-2 and of the Golgi apparatus and the centrosome, all of which reposition asymmetrically to face the cathode. Pharmacological inhibition of Rho-associated coiled-coil forming protein kinases (ROCK) and phosphoinositide 3-kinase decreased, leading neurite orientation and Golgi polarization in the neurons in response to an EF and in parallel decreased the directedness of EF-guided neuronal migration. This work demonstrates that the axis of hippocampal cell division, the establishment of neuronal polarity, the polarization of intracellular structures, and the direction of neuronal migration are all regulated by an extracellular electrical cue.

  14. Planar cell polarity signalling controls cell division orientation during zebrafish gastrulation. (United States)

    Gong, Ying; Mo, Chunhui; Fraser, Scott E


    Oriented cell division is an integral part of pattern development in processes ranging from asymmetric segregation of cell-fate determinants to the shaping of tissues. Despite proposals that it has an important function in tissue elongation, the mechanisms regulating division orientation have been little studied outside of the invertebrates Caenorhabditis elegans and Drosophila melanogaster. Here, we have analysed mitotic divisions during zebrafish gastrulation using in vivo confocal imaging and found that cells in dorsal tissues preferentially divide along the animal-vegetal axis of the embryo. Establishment of this animal-vegetal polarity requires the Wnt pathway components Silberblick/Wnt11, Dishevelled and Strabismus. Our findings demonstrate an important role for non-canonical Wnt signalling in oriented cell division during zebrafish gastrulation, and indicate that oriented cell division is a driving force for axis elongation. Furthermore, we propose that non-canonical Wnt signalling has a conserved role in vertebrate axis elongation, orienting both cell intercalation and mitotic division.

  15. A Localized Complex of Two Protein Oligomers Controls the Orientation of Cell Polarity. (United States)

    Perez, Adam M; Mann, Thomas H; Lasker, Keren; Ahrens, Daniel G; Eckart, Michael R; Shapiro, Lucy


    Signaling hubs at bacterial cell poles establish cell polarity in the absence of membrane-bound compartments. In the asymmetrically dividing bacterium Caulobacter crescentus, cell polarity stems from the cell cycle-regulated localization and turnover of signaling protein complexes in these hubs, and yet the mechanisms that establish the identity of the two cell poles have not been established. Here, we recapitulate the tripartite assembly of a cell fate signaling complex that forms during the G1-S transition. Using in vivo and in vitro analyses of dynamic polar protein complex formation, we show that a polymeric cell polarity protein, SpmX, serves as a direct bridge between the PopZ polymeric network and the cell fate-directing DivJ histidine kinase. We demonstrate the direct binding between these three proteins and show that a polar microdomain spontaneously assembles when the three proteins are coexpressed heterologously in an Escherichia coli test system. The relative copy numbers of these proteins are essential for complex formation, as overexpression of SpmX in Caulobacter reorganizes the polarity of the cell, generating ectopic cell poles containing PopZ and DivJ. Hierarchical formation of higher-order SpmX oligomers nucleates new PopZ microdomain assemblies at the incipient lateral cell poles, driving localized outgrowth. By comparison to self-assembling protein networks and polar cell growth mechanisms in other bacterial species, we suggest that the cooligomeric PopZ-SpmX protein complex in Caulobacter illustrates a paradigm for coupling cell cycle progression to the controlled geometry of cell pole establishment.IMPORTANCE Lacking internal membrane-bound compartments, bacteria achieve subcellular organization by establishing self-assembling protein-based microdomains. The asymmetrically dividing bacterium Caulobacter crescentus uses one such microdomain to link cell cycle progression to morphogenesis, but the mechanism for the generation of this

  16. Selective functionalization of nanofiber scaffolds to regulate salivary gland epithelial cell proliferation and polarity. (United States)

    Cantara, Shraddha I; Soscia, David A; Sequeira, Sharon J; Jean-Gilles, Riffard P; Castracane, James; Larsen, Melinda


    Epithelial cell types typically lose apicobasal polarity when cultured on 2D substrates, but apicobasal polarity is required for directional secretion by secretory cells, such as salivary gland acinar cells. We cultured salivary gland epithelial cells on poly(lactic-co-glycolic acid) (PLGA) nanofiber scaffolds that mimic the basement membrane, a specialized extracellular matrix, and examined cell proliferation and apicobasal polarization. Although cells proliferated on nanofibers, chitosan-coated nanofiber scaffolds stimulated proliferation of salivary gland epithelial cells. Although apicobasal cell polarity was promoted by the nanofiber scaffolds relative to flat surfaces, as determined by the apical localization of ZO-1, it was antagonized by the presence of chitosan. Neither salivary gland acinar nor ductal cells fully polarized on the nanofiber scaffolds, as determined by the homogenous membrane distribution of the mature tight junction marker, occludin. However, nanofiber scaffolds chemically functionalized with the basement membrane protein, laminin-111, promoted more mature tight junctions, as determined by apical localization of occludin, but did not affect cell proliferation. To emulate the multifunctional capabilities of the basement membrane, bifunctional PLGA nanofibers were generated. Both acinar and ductal cell lines responded to signals provided by bifunctional scaffolds coupled to chitosan and laminin-111, demonstrating the applicability of such scaffolds for epithelial cell types.

  17. Polarity governed selective amplification of through plane proton shuttling in proton exchange membrane fuel cells. (United States)

    Gautam, Manu; Chattanahalli Devendrachari, Mruthyunjayachari; Thimmappa, Ravikumar; Raja Kottaichamy, Alagar; Pottachola Shafi, Shahid; Gaikwad, Pramod; Makri Nimbegondi Kotresh, Harish; Ottakam Thotiyl, Musthafa


    Graphene oxide (GO) anisotropically conducts protons with directional dominance of in plane ionic transport (σ IP) over the through plane (σ TP). In a typical H2-O2 fuel cell, since the proton conduction occurs through the plane during its generation at the fuel electrode, it is indeed inevitable to selectively accelerate GO's σ TP for advancement towards a potential fuel cell membrane. We successfully achieved ∼7 times selective amplification of GO's σ TP by tuning the polarity of the dopant molecule in its nanoporous matrix. The coexistence of strongly non-polar and polar domains in the dopant demonstrated a synergistic effect towards σ TP with the former decreasing the number of water molecules coordinated to protons by ∼3 times, diminishing the effects of electroosmotic drag exerted on ionic movements, and the latter selectively accelerating σ TP across the catalytic layers by bridging the individual GO planes via extensive host guest H-bonding interactions. When they are decoupled, the dopant with mainly non-polar or polar features only marginally enhances the σ TP, revealing that polarity factors contribute to fuel cell relevant transport properties of GO membranes only when they coexist. Fuel cell polarization and kinetic analyses revealed that these multitask dopants increased the fuel cell performance metrics of the power and current densities by ∼3 times compared to the pure GO membranes, suggesting that the functional group factors of the dopants are of utmost importance in GO-based proton exchange membrane fuel cells.

  18. AmotL2 disrupts apical-basal cell polarity and promotes tumour invasion. (United States)

    Mojallal, Mahdi; Zheng, Yujuan; Hultin, Sara; Audebert, Stéphane; van Harn, Tanja; Johnsson, Per; Lenander, Claes; Fritz, Nicolas; Mieth, Christin; Corcoran, Martin; Lembo, Frédérique; Hallström, Marja; Hartman, Johan; Mazure, Nathalie M; Weide, Thomas; Grandér, Dan; Borg, Jean-Paul; Uhlén, Per; Holmgren, Lars


    The establishment and maintenance of apical-basal cell polarity is essential for the functionality of glandular epithelia. Cell polarity is often lost in advanced tumours correlating with acquisition of invasive and malignant properties. Despite extensive knowledge regarding the formation and maintenance of polarity, the mechanisms that deregulate polarity in metastasizing cells remain to be fully characterized. Here we show that AmotL2 expression correlates with loss of tissue architecture in tumours from human breast and colon cancer patients. We further show that hypoxic stress results in activation of c-Fos-dependent expression of AmotL2 leading to loss of polarity. c-Fos/hypoxia-induced p60 AmotL2 interacts with the Crb3 and Par3 polarity complexes retaining them in large vesicles and preventing them from reaching the apical membrane. The resulting loss of polarity potentiates the response to invasive cues in vitro and in vivo in mice. These data provide a molecular mechanism how hypoxic stress deregulates cell polarity during tumour progression.

  19. Mathematical analysis of steady-state solutions in compartment and continuum models of cell polarization. (United States)

    Zheng, Zhenzhen; Chou, Ching-Shan; Yi, Tau-Mu; Nie, Qing


    Cell polarization, in which substances previously uniformly distributed become asymmetric due to external or/and internal stimulation, is a fundamental process underlying cell mobility, cell division, and other polarized functions. The yeast cell S. cerevisiae has been a model system to study cell polarization. During mating, yeast cells sense shallow external spatial gradients and respond by creating steeper internal gradients of protein aligned with the external cue. The complex spatial dynamics during yeast mating polarization consists of positive feedback, degradation, global negative feedback control, and cooperative effects in protein synthesis. Understanding such complex regulations and interactions is critical to studying many important characteristics in cell polarization including signal amplification, tracking dynamic signals, and potential trade-off between achieving both objectives in a robust fashion. In this paper, we study some of these questions by analyzing several models with different spatial complexity: two compartments, three compartments, and continuum in space. The step-wise approach allows detailed characterization of properties of the steady state of the system, providing more insights for biological regulations during cell polarization. For cases without membrane diffusion, our study reveals that increasing the number of spatial compartments results in an increase in the number of steady-state solutions, in particular, the number of stable steady-state solutions, with the continuum models possessing infinitely many steady-state solutions. Through both analysis and simulations, we find that stronger positive feedback, reduced diffusion, and a shallower ligand gradient all result in more steady-state solutions, although most of these are not optimally aligned with the gradient. We explore in the different settings the relationship between the number of steady-state solutions and the extent and accuracy of the polarization. Taken together

  20. Keeping Your Cool (United States)

    ... is another way to keep your body cool! Pack peaches, oranges, watermelon, and grapes in your cooler ... tell ya! To keep your feet cool and blister-free, try wearing shoes that allow your feet ...

  1. Dynamics of cell polarity in tissue morphogenesis: a comparative view from Drosophila and Ciona [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Michael T. Veeman


    Full Text Available Tissues in developing embryos exhibit complex and dynamic rearrangements that shape forming organs, limbs, and body axes. Directed migration, mediolateral intercalation, lumen formation, and other rearrangements influence the topology and topography of developing tissues. These collective cell behaviors are distinct phenomena but all involve the fine-grained control of cell polarity. Here we review recent findings in the dynamics of polarized cell behavior in both the Drosophila ovarian border cells and the Ciona notochord. These studies reveal the remarkable reorganization of cell polarity during organ formation and underscore conserved mechanisms of developmental cell polarity including the Par/atypical protein kinase C (aPKC and planar cell polarity pathways. These two very different model systems demonstrate important commonalities but also key differences in how cell polarity is controlled in tissue morphogenesis. Together, these systems raise important, broader questions on how the developmental control of cell polarity contributes to morphogenesis of diverse tissues across the metazoa.

  2. The acetylenic tricyclic bis(cyano enone), TBE-31, targets microtubule dynamics and cell polarity in migrating cells. (United States)

    Chan, Eddie; Saito, Akira; Honda, Tadashi; Di Guglielmo, Gianni M


    Cell migration is dependent on the microtubule network for structural support as well as for the proper delivery and positioning of polarity proteins at the leading edge of migrating cells. Identification of drugs that target cytoskeletal-dependent cell migration and protein transport in polarized migrating cells is important in understanding the cell biology of normal and tumor cells and can lead to new therapeutic targets in disease processes. Here, we show that the tricyclic compound TBE-31 directly binds to tubulin and interferes with microtubule dynamics, as assessed by end binding 1 (EB1) live cell imaging. Interestingly, this interference is independent of in vitro tubulin polymerization. Using immunofluorescence microscopy, we also observed that TBE-31 interferes with the polarity of migratory cells. The polarity proteins Rac1, IQGAP and Tiam1 were localized at the leading edge of DMSO-treated migrating cell, but were observed to be in multiple protrusions around the cell periphery of TBE-31-treated cells. Finally, we observed that TBE-31 inhibits the migration of Rat2 fibroblasts with an IC50 of 0.75 μM. Taken together, our results suggest that the inhibition of cell migration by TBE-31 may result from the improper maintenance of cell polarity of migrating cells.

  3. Networking for proteins : A yeast two-hybrid and RNAi profiling approach to uncover C. elegans cell polarity regulators

    NARCIS (Netherlands)

    Koorman, T.


    Cell polarity is a near universal trait of life and guides many aspects of animal development. Although a number of key polarity proteins have been identified, many interactions with proteins acting downstream likely remain to be elucidated. Mutations in polarity proteins or deregulation of polarity

  4. A role for Wnt/planar cell polarity signaling during lens fiber cell differentiation? (United States)

    Chen, Y; Stump, R J W; Lovicu, F J; McAvoy, J W


    Wnt signaling through frizzled (Fz) receptors plays key roles in just about every developmental system that has been studied. Several Wnt-Fz signaling pathways have been identified including the Wnt/planar cell polarity (PCP) pathway. PCP signaling is crucial for many developmental processes that require major cytoskeletal rearrangements. Downstream of Fz, PCP signaling is thought to involve the GTPases, Rho, Rac and Cdc42 and regulation of the JNK cascade. Here we report on the localization of these GTPases and JNK in the lens and assess their involvement in the cytoskeletal reorganisation that is a key element of FGF-induced lens fiber cell differentiation.

  5. Cell shape, spreading symmetry, and the polarization of stress-fibers in cells

    Energy Technology Data Exchange (ETDEWEB)

    Zemel, A [Institute of Dental Sciences, Faculty of Dental Medicine, and the Fritz Haber Center for Molecular Dynamics, Hebrew University-Hadassah Medical Center, Jerusalem, 91120 (Israel); Rehfeldt, F [III. Physikalisches Institut, Georg-August-Universitaet, 37077 Goettingen (Germany); Brown, A E X [Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Discher, D E [Graduate Group of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104 (United States); Safran, S A [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel)


    The active regulation of cellular forces during cell adhesion plays an important role in the determination of cell size, shape, and internal structure. While on flat, homogeneous and isotropic substrates some cells spread isotropically, others spread anisotropically and assume elongated structures. In addition, in their native environment as well as in vitro experiments, the cell shape and spreading asymmetry can be modulated by the local distribution of adhesive molecules and topography of the environment. We present a simple elastic model and experiments on stem cells to explain the variation of cell size with the matrix rigidity. In addition, we predict the experimental consequences of two mechanisms of acto-myosin polarization and focus here on the effect of the cell spreading asymmetry on the regulation of the stress-fiber alignment in the cytoskeleton. We show that when cell spreading is sufficiently asymmetric the alignment of acto-myosin forces in the cell increases monotonically with the matrix rigidity; however, in general this alignment is non-monotonic, as shown previously. These results highlight the importance of the symmetry characteristics of cell spreading in the regulation of cytoskeleton structure and suggest a mechanism by which different cell types may acquire different morphologies and internal structures in different mechanical environments.

  6. Cell shape, spreading symmetry, and the polarization of stress-fibers in cells (United States)

    Zemel, A.; Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.


    The active regulation of cellular forces during cell adhesion plays an important role in the determination of cell size, shape, and internal structure. While on flat, homogeneous and isotropic substrates some cells spread isotropically, others spread anisotropically and assume elongated structures. In addition, in their native environment as well as in vitro experiments, the cell shape and spreading asymmetry can be modulated by the local distribution of adhesive molecules and topography of the environment. We present a simple elastic model and experiments on stem cells to explain the variation of cell size with the matrix rigidity. In addition, we predict the experimental consequences of two mechanisms of acto-myosin polarization and focus here on the effect of the cell spreading asymmetry on the regulation of the stress-fiber alignment in the cytoskeleton. We show that when cell spreading is sufficiently asymmetric the alignment of acto-myosin forces in the cell increases monotonically with the matrix rigidity; however, in general this alignment is non-monotonic, as shown previously. These results highlight the importance of the symmetry characteristics of cell spreading in the regulation of cytoskeleton structure and suggest a mechanism by which different cell types may acquire different morphologies and internal structures in different mechanical environments.

  7. Expression of planar cell polarity genes during development of the mouse CNS. (United States)

    Tissir, Fadel; Goffinet, André M


    Atypical cadherin (Celsr3) and the receptor Frizzled3 (Fzd3) are crucial for the development of axonal tracts in the mouse CNS. Celsr3 and Fzd3 are orthologues of the Drosophila'planar cell polarity' (PCP) genes flamingo/starry night (fmi/stan) and frizzled, respectively. Reasoning that Celsr3 and Fzd3 might interact with PCP orthologues in mammals like they do in flies, we used mRNA in situ hybridization to compare the expression of Celsr3 and Fzd3 with that of dishevelled 1, 2 and 3 (Dvl1-3), van gogh-like 1 and 2 (Vangl1, 2), and prickle-like 1 and 2 (Prickle1, 2), during mouse CNS development, from embryonic day 10.5 to postnatal day 21. With the relative exception of Vangl1, all genes were expressed in the developing CNS. Although Celsr3- and Fzd3-deficient mice have similar phenotypes, Fzd3 expression was more widespread than that of Celsr3. Vangl2 and Dvl2 were preferentially expressed in ventricular zones, in keeping with their role during neural tube closure, where they could be partners of Celsr1. Dvl1 had a broad expression, reminiscent of that of Celsr2, and may be involved in neural maintenance. A large overlap in the expression territories of Dvl genes suggested redundancy. Vangl1 and Prickle1 had expression canvases different from each other and from other candidates, indicating unrelated function. Like Celsr3, Dvl3 and Prickle2 were expressed more strongly in postmitotic neurons than in precursors. Thus, the analogy between the PCP and Celsr3-Fzd3 genetic networks is limited, but may include Dvl3 and/or Prickle2.

  8. Control of planar cell polarity by interaction of DWnt4 and four-jointed. (United States)

    Lim, Janghoo; Norga, Koenraad K; Chen, Zhihong; Choi, Kwang-Wook


    The Drosophila eye and the wing display specific planar cell polarity. Although Frizzled (Fz) signaling has been implicated in the establishment of ommatidial and wing hair polarity, evidence for the Wnt gene function has been limited. Here we examined the function of a Drosophila homolog of Wnt4 (DWnt4) in the control of planar polarity. We show that DWnt4 mRNA and protein are preferentially expressed in the ventral region of eye disc. DWnt4 mutant eyes show polarity reversals mostly in the ventral domain, consistent with the ventral expression of DWnt4. Ectopic expression of DWnt4 in the dorsoventral (DV) polar margins is insufficient to induce ommatidial polarity but becomes inductive when coexpressed with Four-jointed (Fj). Similarly, DWnt4 and Fj result in synergistic induction of hair polarity toward the source of expression in the wing. Consistent with genetic interaction, we provide evidence for direct interaction of DWnt4 and Fj transmembrane protein. The extracellular domain of Fj is required for direct binding to DWnt4 and for the induction of hair polarity. In contrast to the synergy between DWnt4 and Fj, DWnt4 antagonizes the polarizing effect of Fz. Our results suggest that DWnt4 is involved in ommatidial polarity signaling in the ventral region of the eye and its function is mediated by interacting with Fj.

  9. Mechanisms of Cell Polarity-Controlled Epithelial Homeostasis and Immunity in the Intestine

    NARCIS (Netherlands)

    Klunder, Leon J; Faber, Klaas Nico; Dijkstra, Gerard; van IJzendoorn, Sven C D


    Intestinal epithelial cell polarity is instrumental to maintain epithelial homeostasis and balance communications between the gut lumen and bodily tissue, thereby controlling the defense against gastrointestinal pathogens and maintenance of immune tolerance to commensal bacteria. In this review, we

  10. Cells must express components of the planar cell polarity system and extracellular matrix to support cytonemes. (United States)

    Huang, Hai; Kornberg, Thomas B


    Drosophila dorsal air sac development depends on Decapentaplegic (Dpp) and Fibroblast growth factor (FGF) proteins produced by the wing imaginal disc and transported by cytonemes to the air sac primordium (ASP). Dpp and FGF signaling in the ASP was dependent on components of the planar cell polarity (PCP) system in the disc, and neither Dpp- nor FGF-receiving cytonemes extended over mutant disc cells that lacked them. ASP cytonemes normally navigate through extracellular matrix (ECM) composed of collagen, laminin, Dally and Dally-like (Dlp) proteins that are stratified in layers over the disc cells. However, ECM over PCP mutant cells had reduced levels of laminin, Dally and Dlp, and whereas Dpp-receiving ASP cytonemes navigated in the Dally layer and required Dally (but not Dlp), FGF-receiving ASP cytonemes navigated in the Dlp layer, requiring Dlp (but not Dally). These findings suggest that cytonemes interact directly and specifically with proteins in the stratified ECM.

  11. Cell polarity and spindle orientation in the distal epithelium of embryonic lung. (United States)

    El-Hashash, Ahmed H; Warburton, David


    A proper balance between self-renewal and differentiation of lung-specific progenitors at the distal epithelial tips is absolutely required for normal lung morphogenesis. Cell polarity and mitotic spindle orientation play a critical role in the self-renewal/differentiation of epithelial cells and can impact normal physiological processes, including epithelial tissue branching and differentiation. Therefore, understanding the behavior of lung distal epithelial progenitors could identify innovative solutions to restoring normal lung morphogenesis. Yet little is known about cell polarity, spindle orientation, and segregation of cell fate determinant in the embryonic lung epithelium, which contains progenitor cells. Herein, we provide the first evidence that embryonic lung distal epithelium is polarized and highly mitotic with characteristic perpendicular cell divisions. Consistent with these findings, mInsc, LGN, and NuMA polarity proteins, which control spindle orientation, are asymmetrically localized in mitotic distal epithelial progenitors of embryonic lungs. Furthermore, the cell fate determinant Numb is asymmetrically distributed at the apical side of distal epithelial progenitors and segregated to one daughter cell in most mitotic cells. These findings provide evidence for polarity in distal epithelial progenitors of embryonic lungs and provide a framework for future translationally oriented studies in this area.

  12. Polarity determination in breast tissue: Desmosomal adhesion, myoepit helial cells, and laminin 1

    Energy Technology Data Exchange (ETDEWEB)

    Bissell, Mina J.; Bilder, David


    In all epithelial organs, apicobasal polarity determines functional integrity and contributes to the maintenance of tissue and organ specificity. In the breast, the functional unit is a polar double-layered tube consisting of luminal epithelial cells surrounded by myoepithelial cells and a basement membrane. It is far from clear how this double-layered structure is established and how polarity is maintained. Two recent papers have shed some light onto this intriguing problem in mammary gland biology. The results point to desmosomes and laminin 1 as having crucial roles. However, some questions remain.

  13. Porcine aminopeptidase N mediated polarized infection by porcine epidemic diarrhea virus in target cells

    Energy Technology Data Exchange (ETDEWEB)

    Cong, Yingying; Li, Xiaoxue; Bai, Yunyun [College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030 (China); Lv, Xiaonan [College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030 (China); CAS Key Lab for Biomedical Effects of Nanomaterials and Nanosafety, National Center for Nanoscience & Technology of China, Beijing 100090 (China); Herrler, Georg [Institute for Virology, University of Veterinary Medicine, Hannover D-30559 (Germany); Enjuanes, Luis [Department of Molecular and Cell Biology, Centro Nacional de Biotecnología (CNB-CSIC), Campus Universidad Autónoma de Madrid, Cantoblanco, Madrid (Spain); Zhou, Xingdong [College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030 (China); Qu, Bo [Faculty of Life Sciences, Northeast Agricultural University, Harbin 150030 (China); Meng, Fandan [Institute for Virology, University of Veterinary Medicine, Hannover D-30559 (Germany); Cong, Chengcheng [College Animal Husbandry and Veterinary Medicine, Shenyang Agricultural University, Shenyang 110161 (China); Ren, Xiaofeng; Li, Guangxing [College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030 (China)


    Infection of polarized intestinal epithelial cells by porcine epidemic diarrhea virus (PEDV) was characterized. Indirect immunofluorescence assay, real-time PCR, and transmission electron microscopy confirmed PEDV can be successfully propagated in immortalized swine small intestine epithelial cells (IECs). Infection involved porcine aminpeptidase N (pAPN), a reported cellular receptor for PEDV, transient expression of pAPN and siRNA targeted pAPN increased and decreased the infectivity of PEDV in IECs, respectively. Subsequently, polarized entry into and release from both Vero E6 and IECs was analyzed. PEDV entry into polarized cells and pAPN grown on membrane inserts occurs via apical membrane. The progeny virus released into the medium was also quantified which demonstrated that PEDV is preferentially released from the apical membrane. Collectively, our data demonstrate that pAPN, the cellular receptor for PEDV, mediates polarized PEDV infection. These results imply the possibility that PEDV infection may proceed by lateral spread of virus in intestinal epithelial cells. - Highlights: • PEDV infection of polarized intestinal epithelial cells (IECs) was characterized. • Porcine aminpeptidase N (pAPN) facilitated PEDV infection in IECs. • PEDV entry into and release from polarized cell via its apical membrane. • PEDV infection may proceed by lateral spread of virus in IECs.

  14. Active self-polarization of contractile cells in asymmetrically shaped domains (United States)

    Zemel, A.; Safran, S. A.


    Mechanical forces generated by contractile cells allow the cells to sense their environment and to interact with other cells. By locally pulling on their environment, cells can sense and respond to mechanical features such as the local stress (or strain), the shape of a cellular domain, and the surrounding rigidity; at the same time, they also modify the mechanical state of the system. This creates a mechanical feedback loop that can result in self-polarization of cells. In this paper, we present a quantitative mechanical model that predicts the self-polarization of cells in spheroidally shaped domains, comprising contractile cells and an elastic matrix, that are embedded in a three-dimensional, cell-free gel. The theory is based on a generalization of the known results for passive inclusions in solids to include the effects of cell activity. We use the active cellular susceptibility tensor presented by Zemel [Phys. Rev. Lett. 97, 128103 (2006)] to calculate the polarization response and hence the elastic stress field developed by the cells in the cellular domain. The cell polarization is analyzed as a function of the shape and the elastic moduli of the cellular domain compared with the cell-free surrounding material. Consistent with experiment, our theory predicts the development of a stronger contractile force for cells in a gel that is surrounded by a large, cell-free material whose elastic modulus is stiffer than that of the gel that contains the cells. This provides a quantitative explanation of the differences in the development of cellular forces as observed in free and fixed gels. In the case of an asymmetrically shaped (spheroidal) domain of cells, we show that the anisotropic elastic field within the domain leads to a spontaneous self-polarization of the cells along the long axis of the domain.

  15. The viral spike protein is not involved in the polarized sorting of coronaviruses in epithelial cells

    NARCIS (Netherlands)

    Rossen, J W; de Beer, R; Godeke, G J; Raamsman, M J; Horzinek, M C; Vennema, H; Rottier, P J


    Coronaviruses are assembled by budding into a pre-Golgi compartment from which they are transported along the secretory pathway to leave the cell. In cultured epithelial cells, they are released in a polarized fashion; depending on the virus and cell type, they are sorted preferentially either to th

  16. Stathmin regulates microtubule dynamics and microtubule organizing center polarization in activated T cells. (United States)

    Filbert, Erin L; Le Borgne, Marie; Lin, Joseph; Heuser, John E; Shaw, Andrey S


    Polarization of T cells involves reorientation of the microtubule organizing center (MTOC). Because activated ERK is localized at the immunological synapse, we investigated its role by showing that ERK activation is important for MTOC polarization. Suspecting that ERK phosphorylates a regulator of microtubules, we next focused on stathmin, a known ERK substrate. Our work indicates that during T cell activation, ERK is recruited to the synapse, allowing it to phosphorylate stathmin molecules near the immunological synapse. Supporting an important role of stathmin phosphorylation in T cell activation, we showed that T cell activation results in increased microtubule growth rate dependent on the presence of stathmin. The significance of this finding was demonstrated by results showing that CTLs from stathmin(-/-) mice displayed defective MTOC polarization and defective target cell cytolysis. These data implicate stathmin as a regulator of the microtubule network during T cell activation.

  17. Flamingo, a seven-pass transmembrane cadherin, regulates planar cell polarity under the control of Frizzled. (United States)

    Usui, T; Shima, Y; Shimada, Y; Hirano, S; Burgess, R W; Schwarz, T L; Takeichi, M; Uemura, T


    We identified a seven-pass transmembrane receptor of the cadherin superfamily, designated Flamingo (Fmi), localized at cell-cell boundaries in the Drosophila wing. In the absence of Fmi, planar polarity was distorted. Before morphological polarization of wing cells along the proximal-distal (P-D) axis, Fmi was redistributed predominantly to proximal and distal cell edges. This biased localization of Fmi appears to be driven by an imbalance of the activity of Frizzled (Fz) across the proximal/distal cell boundary. These results, together with phenotypes caused by ectopic expression of fz and fmi, suggest that cells acquire the P-D polarity by way of the Fz-dependent boundary localization of Fmi.

  18. Reciprocity between Regulatory T Cells and Th17 Cells: Relevance to Polarized Immunity in Leprosy. (United States)

    Sadhu, Soumi; Khaitan, Binod Kumar; Joshi, Beenu; Sengupta, Utpal; Nautiyal, Arvind Kumar; Mitra, Dipendra Kumar


    T cell defect is a common feature in lepromatous or borderline lepromatous leprosy (LL/BL) patients in contrast to tuberculoid or borderline tuberculoid type (TT/BT) patients. Tuberculoid leprosy is characterized by strong Th1-type cell response with localized lesions whereas lepromatous leprosy is hallmarked by its selective Mycobacterium leprae specific T cell anergy leading to disseminated and progressive disease. FoxP3+ Regulatory T cells (Treg) which are essential for maintaining peripheral tolerance, preventing autoimmune diseases and limiting chronic inflammatory diseases also dampen proinflammatory T cells that include T helper 17 (Th17) cells. This study is aimed at evaluating the role of Treg cells in influencing other effector T cells and its relationship with the cytokine polarized state in leprosy patients. Peripheral blood mononuclear cells from of BT/TT (n = 15) and BL/LL (n = 15) patients were stimulated with M. leprae antigen (WCL) in presence of golgi transport inhibitor monensin for FACS based intracellular cytokine estimation. The frequency of Treg cells showed >5-fold increase in BL/LL in comparison to BT/TT and healthy contacts. These cells produced suppressive cytokine, IL-10 in BL/LL as opposed to BT/TT (p = 0.0200) indicating their suppressive function. The frequency of Th17 cells (CD4, CD45RO, IL-17) was, however, higher in BT/TT. Significant negative correlation (r = -0.68, P = 0.03) was also found between IL-10 of Treg cells and IL-17+ T cells in BL/LL. Blocking IL-10/TGF-β restored the IL-17+ T cells in BL/LL patients. Simultaneously, presence of Th17 related cytokines (TGF-β, IL-6, IL-17 and IL-23) decreased the number of FoxP3+ Treg cells concomitantly increasing IL-17 producing CD4+ cells in lepromatous leprosy. Higher frequency of Programmed Death-1/PD-1+ Treg cells and its ligand, PDL-1 in antigen presenting cells (APCs) was found in BL/LL patients. Inhibition of this pathway led to rescue of IFN-γ and IL-17 producing T cells

  19. Rules of chemokine receptor association with T cell polarization in vivo (United States)

    Kim, Chang H.; Rott, Lusijah; Kunkel, Eric J.; Genovese, Mark C.; Andrew, David P.; Wu, Lijun; Butcher, Eugene C.


    Current concepts of chemokine receptor (CKR) association with Th1 and Th2 cell polarization and effector function have largely ignored the diverse nature of effector and memory T cells in vivo. Here, we systematically investigated the association of 11 CKRs, singly or in combination, with CD4 T cell polarization. We show that Th1, Th2, Th0, and nonpolarized T cells in blood and tissue can express any of the CKRs studied but that each CKR defines a characteristic pool of polarized and nonpolarized CD4 T cells. Certain combinations of CKRs define populations that are markedly enriched in major subsets of Th1 versus Th2 cells. For example, although Th0, Th1, and Th2 cells are each found among blood CD4 T cells coordinately expressing CXCR3 and CCR4, Th1 but not Th2 cells can be CXCR3+CCR4–, and Th2 but only rare Th1 cells are CCR4+CXCR3–. Contrary to recent reports, although CCR7– cells contain a higher frequency of polarized CD4 T cells, most Th1 and Th2 effector cells are CCR7+ and thus may be capable of lymphoid organ homing. Interestingly, Th1-associated CKRs show little or no preference for Th1 cells except when they are coexpressed with CXCR3. We conclude that the combinatorial expression of CKRs, which allow tissue- and subset-dependent targeting of effector cells during chemotactic navigation, defines physiologically significant subsets of polarized and nonpolarized T cells. PMID:11696578

  20. The Hippo pathway polarizes the actin cytoskeleton during collective migration of Drosophila border cells. (United States)

    Lucas, Eliana P; Khanal, Ichha; Gaspar, Pedro; Fletcher, Georgina C; Polesello, Cedric; Tapon, Nicolas; Thompson, Barry J


    Collective migration of Drosophila border cells depends on a dynamic actin cytoskeleton that is highly polarized such that it concentrates around the outer rim of the migrating cluster of cells. How the actin cytoskeleton becomes polarized in these cells to enable collective movement remains unknown. Here we show that the Hippo signaling pathway links determinants of cell polarity to polarization of the actin cytoskeleton in border cells. Upstream Hippo pathway components localize to contacts between border cells inside the cluster and signal through the Hippo and Warts kinases to polarize actin and promote border cell migration. Phosphorylation of the transcriptional coactivator Yorkie (Yki)/YAP by Warts does not mediate the function of this pathway in promoting border cell migration, but rather provides negative feedback to limit the speed of migration. Instead, Warts phosphorylates and inhibits the actin regulator Ena to activate F-actin Capping protein activity on inner membranes and thereby restricts F-actin polymerization mainly to the outer rim of the migrating cluster.

  1. The tumor suppressor Lgl1 regulates front-rear polarity of migrating cells. (United States)

    Ravid, Shoshana


    Cell migration is a highly integrated, multistep process that plays an important role in physiological and pathological processes. The migrating cell is highly polarized, with complex regulatory pathways that integrate its component processes spatially and temporally. The Drosophila tumor suppressor, Lethal (2) giant larvae (Lgl), regulates apical-basal polarity in epithelia and asymmetric cell division. But little is known about the role of Lgl in establishing cell polarity in migrating cells. Recently, we showed that the mammalian Lgl1 interacts directly with non-muscle myosin IIA (NMIIA), inhibiting its ability to assemble into filaments in vitro. Lgl1 also regulates the cellular localization of NMIIA, the maturation of focal adhesions, and cell migration. We further showed that phosphorylation of Lgl1 by aPKCζ prevents its interaction with NMIIA and is important for Lgl1 and acto-NMII cytoskeleton cellular organization. Lgl is a critical downstream target of the Par6-aPKC cell polarity complex; we showed that Lgl1 forms two distinct complexes in vivo, Lgl1-NMIIA and Lgl1-Par6-aPKCζ in different cellular compartments. We further showed that aPKCζ and NMIIA compete to bind directly to Lgl1 through the same domain. These data provide new insights into the role of Lgl1, NMIIA, and Par6-aPKCζ in establishing front-rear polarity in migrating cells. In this commentary, I discuss the role of Lgl1 in the regulation of the acto-NMII cytoskeleton and its regulation by the Par6-aPKCζ polarity complex, and how Lgl1 activity may contribute to the establishment of front-rear polarity in migrating cells.

  2. Myosin Id is required for planar cell polarity in ciliated tracheal and ependymal epithelial cells. (United States)

    Hegan, Peter S; Ostertag, Eric; Geurts, Aron M; Mooseker, Mark S


    In wild type (WT) tracheal epithelial cells, ciliary basal bodies are oriented such that all cilia on the cell surface beat in the same upward direction. This precise alignment of basal bodies and, as a result, the ciliary axoneme, is termed rotational planar cell polarity (PCP). Rotational PCP in the multi-ciliated epithelial cells of the trachea is perturbed in rats lacking myosin Id (Myo1d). Myo1d is localized in the F-actin and basal body rich subapical cortex of the ciliated tracheal epithelial cell. Scanning and transmission electron microscopy of Myo1d knock out (KO) trachea revealed that the unidirectional bending pattern is disrupted. Instead, cilia splay out in a disordered, often radial pattern. Measurement of the alignment axis of the central pair axonemal microtubules was much more variable in the KO, another indicator that rotational PCP is perturbed. The asymmetric localization of the PCP core protein Vangl1 is lost. Both the velocity and linearity of cilia-driven movement of beads above the tracheal mucosal surface was impaired in the Myo1d KO. Multi-ciliated brain ependymal epithelial cells exhibit a second form of PCP termed translational PCP in which basal bodies and attached cilia are clustered at the anterior side of the cell. The precise asymmetric clustering of cilia is disrupted in the ependymal cells of the Myo1d KO rat. While basal body clustering is maintained, left-right positioning of the clusters is lost.

  3. Differential effects of Mycobacterium bovis - derived polar and apolar lipid fractions on bovine innate immune cells

    Directory of Open Access Journals (Sweden)

    Pirson Chris


    Full Text Available Abstract Mycobacterial lipids have long been known to modulate the function of a variety of cells of the innate immune system. Here, we report the extraction and characterisation of polar and apolar free lipids from Mycobacterium bovis AF 2122/97 and identify the major lipids present in these fractions. Lipids found included trehalose dimycolate (TDM and trehalose monomycolate (TMM, the apolar phthiocerol dimycocersates (PDIMs, triacyl glycerol (TAG, pentacyl trehalose (PAT, phenolic glycolipid (PGL, and mono-mycolyl glycerol (MMG. Polar lipids identified included glucose monomycolate (GMM, diphosphatidyl glycerol (DPG, phenylethanolamine (PE and a range of mono- and di-acylated phosphatidyl inositol mannosides (PIMs. These lipid fractions are capable of altering the cytokine profile produced by fresh and cultured bovine monocytes as well as monocyte derived dendritic cells. Significant increases in the production of IL-10, IL-12, MIP-1β, TNFα and IL-6 were seen after exposure of antigen presenting cells to the polar lipid fraction. Phenotypic characterisation of the cells was performed by flow cytometry and significant decreases in the expression of MHCII, CD86 and CD1b were found after exposure to the polar lipid fraction. Polar lipids also significantly increased the levels of CD40 expressed by monocytes and cultured monocytes but no effect was seen on the constitutively high expression of CD40 on MDDC or on the levels of CD80 expressed by any of the cells. Finally, the capacity of polar fraction treated cells to stimulate alloreactive lymphocytes was assessed. Significant reduction in proliferative activity was seen after stimulation of PBMC by polar fraction treated cultured monocytes whilst no effect was seen after lipid treatment of MDDC. These data demonstrate that pathogenic mycobacterial polar lipids may significantly hamper the ability of the host APCs to induce an appropriate immune response to an invading pathogen.

  4. Auxin Acts through MONOPTEROS to Regulate Plant Cell Polarity and Pattern Phyllotaxis. (United States)

    Bhatia, Neha; Bozorg, Behruz; Larsson, André; Ohno, Carolyn; Jönsson, Henrik; Heisler, Marcus G


    The periodic formation of plant organs such as leaves and flowers gives rise to intricate patterns that have fascinated biologists and mathematicians alike for hundreds of years [1]. The plant hormone auxin plays a central role in establishing these patterns by promoting organ formation at sites where it accumulates due to its polar, cell-to-cell transport [2-6]. Although experimental evidence as well as modeling suggest that feedback from auxin to its transport direction may help specify phyllotactic patterns [7-12], the nature of this feedback remains unclear [13]. Here we reveal that polarization of the auxin efflux carrier PIN-FORMED 1 (PIN1) is regulated by the auxin response transcription factor MONOPTEROS (MP) [14]. We find that in the shoot, cell polarity patterns follow MP expression, which in turn follows auxin distribution patterns. By perturbing MP activity both globally and locally, we show that localized MP activity is necessary for the generation of polarity convergence patterns and that localized MP expression is sufficient to instruct PIN1 polarity directions non-cell autonomously, toward MP-expressing cells. By expressing MP in the epidermis of mp mutants, we further show that although MP activity in a single-cell layer is sufficient to promote polarity convergence patterns, MP in sub-epidermal tissues helps anchor these polarity patterns to the underlying cells. Overall, our findings reveal a patterning module in plants that determines organ position by orienting transport of the hormone auxin toward cells with high levels of MP-mediated auxin signaling. We propose that this feedback process acts broadly to generate periodic plant architectures.

  5. A modeling approach to study the effect of cell polarization on keratinocyte migration.

    Directory of Open Access Journals (Sweden)

    Matthias Jörg Fuhr

    Full Text Available The skin forms an efficient barrier against the environment, and rapid cutaneous wound healing after injury is therefore essential. Healing of the uppermost layer of the skin, the epidermis, involves collective migration of keratinocytes, which requires coordinated polarization of the cells. To study this process, we developed a model that allows analysis of live-cell images of migrating keratinocytes in culture based on a small number of parameters, including the radius of the cells, their mass and their polarization. This computational approach allowed the analysis of cell migration at the front of the wound and a reliable identification and quantification of the impaired polarization and migration of keratinocytes from mice lacking fibroblast growth factors 1 and 2--an established model of impaired healing. Therefore, our modeling approach is suitable for large-scale analysis of migration phenotypes of cells with specific genetic defects or upon treatment with different pharmacological agents.

  6. A two-step mechanism underlies the planar polarization of regenerating sensory hair cells. (United States)

    López-Schier, Hernán; Hudspeth, A J


    The restoration of planar cell polarity is an essential but poorly understood step toward physiological recovery during sensory-organ regeneration. Investigating this issue in the lateral line of the zebrafish, we found that hair cells regenerate in pairs along a single axis established by the restricted localization and oriented division of their progenitors. By analyzing mutants lacking the planar-polarity determinant Vangl2, we ascertained that the uniaxial production of hair cells and the subsequent orientation of their hair bundles are controlled by distinct pathways, whose combination underlies the establishment of hair-cell orientation during development and regeneration. This mechanism may represent a general principle governing the long-term maintenance of planar cell polarity in remodeling epithelia.

  7. Loss of GM130 in breast cancer cells and its effects on cell migration, invasion and polarity. (United States)

    Baschieri, Francesco; Uetz-von Allmen, Edith; Legler, Daniel F; Farhan, Hesso


    Spatially distinct pools of the small GTPase Cdc42 were observed, but the major focus of research so far has been to investigate its signaling at the plasma membrane. We recently showed that the Golgi pool of Cdc42 is relevant for cell polarity and that it is regulated by GM130, a Golgi matrix protein. Loss of GM130 abrogated cell polarity and consistent with the notion that polarity is frequently impaired in cancer, we found that GM130 is downregulated in colorectal cancer. Whether the loss of GM130 solely affects polarity, or whether it affects other processes relevant for tumorigenesis remains unclear. In a panel of breast cancer cells lines, we investigated the consequences of GM130 depletion on traits of relevance for tumor progression, such as survival, proliferation, adhesion, migration and invasion. We show that cellular assays that depend on polarity, such as chemotaxis and wound scratch assays, are only of limited use to investigate the role of polarity modulators in cancer. Depletion of GM130 increases cellular velocity and increases the invasiveness of breast cancer cells, therefore supporting the view that alterations of polarity contribute to tumor progression.

  8. Mammalian aPKC/Par polarity complex mediated regulation of epithelial division orientation and cell fate

    Energy Technology Data Exchange (ETDEWEB)

    Vorhagen, Susanne; Niessen, Carien M., E-mail:


    Oriented cell division is a key regulator of tissue architecture and crucial for morphogenesis and homeostasis. Balanced regulation of proliferation and differentiation is an essential property of tissues not only to drive morphogenesis but also to maintain and restore homeostasis. In many tissues orientation of cell division is coupled to the regulation of differentiation producing daughters with similar (symmetric cell division, SCD) or differential fate (asymmetric cell division, ACD). This allows the organism to generate cell lineage diversity from a small pool of stem and progenitor cells. Division orientation and/or the ratio of ACD/SCD need to be tightly controlled. Loss of orientation or an altered ratio can promote overgrowth, alter tissue architecture and induce aberrant differentiation, and have been linked to morphogenetic diseases, cancer and aging. A key requirement for oriented division is the presence of a polarity axis, which can be established through cell intrinsic and/or extrinsic signals. Polarity proteins translate such internal and external cues to drive polarization. In this review we will focus on the role of the polarity complex aPKC/Par3/Par6 in the regulation of division orientation and cell fate in different mammalian epithelia. We will compare the conserved function of this complex in mitotic spindle orientation and distribution of cell fate determinants and highlight common and differential mechanisms in which this complex is used by tissues to adapt division orientation and cell fate to the specific properties of the epithelium.

  9. Cell polarity and neurogenesis in embryonic stem cell-derived neural rosettes. (United States)

    Banda, Erin; McKinsey, Anna; Germain, Noelle; Carter, James; Anderson, Nickesha Camille; Grabel, Laura


    Embryonic stem cells (ESCs) undergoing neural differentiation form radial arrays of neural stem cells, termed neural rosettes. These structures manifest many of the properties associated with embryonic and adult neurogenesis, including cell polarization, interkinetic nuclear migration (INM), and a gradient of neuronal differentiation. We now identify novel rosette structural features that serve to localize key regulators of neurogenesis. Cells within neural rosettes have specialized basal as well as apical surfaces, based on localization of the extracellular matrix receptor β1 integrin. Apical processes of cells in mature rosettes terminate at the lumen, where adherens junctions are apparent. Primary cilia are randomly distributed in immature rosettes and tightly associated with the neural stem cell's apical domain as rosettes mature. Components of two signaling pathways known to regulate neurogenesis in vivo and in rosettes, Hedgehog and Notch, are apically localized, with the Hedgehog effector Smoothened (Smo) associated with primary cilia and the Notch pathway γ-secretase subunit Presenilin 2 associated with the adherens junction. Increased neuron production upon treatment with the Notch inhibitor DAPT suggests a major role for Notch signaling in maintaining the neural stem cell state, as previously described. A less robust outcome was observed with manipulation of Hedgehog levels, though consistent with a role in neural stem cell survival or proliferation. Inhibition of both pathways resulted in an additive effect. These data support a model by which cells extending a process to the rosette lumen maintain neural stem cell identity whereas release from this association, either through asymmetric cell division or apical abscission, promotes neuronal differentiation.

  10. Keeping the Records Straight. (United States)

    Clift, Phil; Keynes, Milton


    Guidelines are given regarding keeping and using educational records for exceptional children in Great Britain. Procedures related to anecdotal records, observation inventories, and rating scales are delineated. (CL)

  11. Polar delivery in plants; commonalities and differences to animal epithelial cells. (United States)

    Kania, Urszula; Fendrych, Matyaš; Friml, Jiři


    Although plant and animal cells use a similar core mechanism to deliver proteins to the plasma membrane, their different lifestyle, body organization and specific cell structures resulted in the acquisition of regulatory mechanisms that vary in the two kingdoms. In particular, cell polarity regulators do not seem to be conserved, because genes encoding key components are absent in plant genomes. In plants, the broad knowledge on polarity derives from the study of auxin transporters, the PIN-FORMED proteins, in the model plant Arabidopsis thaliana. In animals, much information is provided from the study of polarity in epithelial cells that exhibit basolateral and luminal apical polarities, separated by tight junctions. In this review, we summarize the similarities and differences of the polarization mechanisms between plants and animals and survey the main genetic approaches that have been used to characterize new genes involved in polarity establishment in plants, including the frequently used forward and reverse genetics screens as well as a novel chemical genetics approach that is expected to overcome the limitation of classical genetics methods.

  12. Heparan Sulfate Proteoglycans Regulate Fgf Signaling and Cell Polarity during Collective Cell Migration

    Directory of Open Access Journals (Sweden)

    Marina Venero Galanternik


    Full Text Available Collective cell migration is a highly regulated morphogenetic movement during embryonic development and cancer invasion that involves the precise orchestration and integration of cell-autonomous mechanisms and environmental signals. Coordinated lateral line primordium migration is controlled by the regulation of chemokine receptors via compartmentalized Wnt/β-catenin and fibroblast growth factor (Fgf signaling. Analysis of mutations in two exostosin glycosyltransferase genes (extl3 and ext2 revealed that loss of heparan sulfate (HS chains results in a failure of collective cell migration due to enhanced Fgf ligand diffusion and loss of Fgf signal transduction. Consequently, Wnt/β-catenin signaling is activated ectopically, resulting in the subsequent loss of the chemokine receptor cxcr7b. Disruption of HS proteoglycan (HSPG function induces extensive, random filopodia formation, demonstrating that HSPGs are involved in maintaining cell polarity in collectively migrating cells. The HSPGs themselves are regulated by the Wnt/β-catenin and Fgf pathways and thus are integral components of the regulatory network that coordinates collective cell migration with organ specification and morphogenesis.

  13. Shaping the nervous system: role of the core planar cell polarity genes. (United States)

    Tissir, Fadel; Goffinet, André M


    Planar cell polarity (PCP) is complementary to the intrinsic polarization of single cells and refers to the global coordination of cell behaviour in the plane of a tissue and, by extension, to the signalling pathways that control it. PCP is most evident in cell sheets, and research into PCP was for years confined to studies in Drosophila melanogaster. However, PCP has more recently emerged as an important phenomenon in vertebrates, in which it regulates various developmental processes and is associated with multiple disorders. In particular, core PCP genes are crucial for the development and function of the nervous system. They are involved in neural tube closure, ependymal polarity, neuronal migration, dendritic growth and axon guidance.

  14. Disruption of Bardet-Biedl syndrome ciliary proteins perturbs planar cell polarity in vertebrates. (United States)

    Ross, Alison J; May-Simera, Helen; Eichers, Erica R; Kai, Masatake; Hill, Josephine; Jagger, Daniel J; Leitch, Carmen C; Chapple, J Paul; Munro, Peter M; Fisher, Shannon; Tan, Perciliz L; Phillips, Helen M; Leroux, Michel R; Henderson, Deborah J; Murdoch, Jennifer N; Copp, Andrew J; Eliot, Marie-Madeleine; Lupski, James R; Kemp, David T; Dollfus, Hélène; Tada, Masazumi; Katsanis, Nicholas; Forge, Andrew; Beales, Philip L


    The evolutionarily conserved planar cell polarity (PCP) pathway (or noncanonical Wnt pathway) drives several important cellular processes, including epithelial cell polarization, cell migration and mitotic spindle orientation. In vertebrates, PCP genes have a vital role in polarized convergent extension movements during gastrulation and neurulation. Here we show that mice with mutations in genes involved in Bardet-Biedl syndrome (BBS), a disorder associated with ciliary dysfunction, share phenotypes with PCP mutants including open eyelids, neural tube defects and disrupted cochlear stereociliary bundles. Furthermore, we identify genetic interactions between BBS genes and a PCP gene in both mouse (Ltap, also called Vangl2) and zebrafish (vangl2). In zebrafish, the augmented phenotype results from enhanced defective convergent extension movements. We also show that Vangl2 localizes to the basal body and axoneme of ciliated cells, a pattern reminiscent of that of the BBS proteins. These data suggest that cilia are intrinsically involved in PCP processes.

  15. Roles of planar cell polarity pathways in the development of neutral tube defects

    Directory of Open Access Journals (Sweden)

    Hua Yimin


    Full Text Available Abstract Neural tube defects (NTDs are the second most common birth defect in humans. Despite many advances in the understanding of NTDs and the identification of many genes related to NTDs, the fundamental etiology for the majority of cases of NTDs remains unclear. Planar cell polarity (PCP signaling pathway, which is important for polarized cell movement (such as cell migration and organ morphogenesis through the activation of cytoskeletal pathways, has been shown to play multiple roles during neural tube closure. The disrupted function of PCP pathway is connected with some NTDs. Here, we summarize our current understanding of how PCP factors affect the pathogenesis of NTDs.

  16. Planar cell polarity signaling in collective cell movements during morphogenesis and disease. (United States)

    Muñoz-Soriano, Verónica; Belacortu, Yaiza; Paricio, Nuria


    Collective and directed cell movements are crucial for diverse developmental processes in the animal kingdom, but they are also involved in wound repair and disease. During these processes groups of cells are oriented within the tissue plane, which is referred to as planar cell polarity (PCP). This requires a tight regulation that is in part conducted by the PCP pathway. Although this pathway was initially characterized in flies, subsequent studies in vertebrates revealed a set of conserved core factors but also effector molecules and signal modulators, which build the fundamental PCP machinery. The PCP pathway in Drosophila regulates several developmental processes involving collective cell movements such as border cell migration during oogenesis, ommatidial rotation during eye development, and embryonic dorsal closure. During vertebrate embryogenesis, PCP signaling also controls collective and directed cell movements including convergent extension during gastrulation, neural tube closure, neural crest cell migration, or heart morphogenesis. Similarly, PCP signaling is linked to processes such as wound repair, and cancer invasion and metastasis in adults. As a consequence, disruption of PCP signaling leads to pathological conditions. In this review, we will summarize recent findings about the role of PCP signaling in collective cell movements in flies and vertebrates. In addition, we will focus on how studies in Drosophila have been relevant to our understanding of the PCP molecular machinery and will describe several developmental defects and human disorders in which PCP signaling is compromised. Therefore, new discoveries about the contribution of this pathway to collective cell movements could provide new potential diagnostic and therapeutic targets for these disorders.

  17. Keeping Your Balance (United States)

    ... News & Events Press Releases NOF in the News Osteoporosis in the News Press/Media Kit NOF Events Blog Advocacy NOF Store Shopping Cart Home › Patients › Fractures/Fall Prevention › Exercise/Safe Movement › Keeping Your Balance Keeping Your Balance ...

  18. A Three-Dimensional Cell Culture Model To Study Enterovirus Infection of Polarized Intestinal Epithelial Cells. (United States)

    Drummond, Coyne G; Nickerson, Cheryl A; Coyne, Carolyn B


    Despite serving as the primary entry portal for coxsackievirus B (CVB), little is known about CVB infection of the intestinal epithelium, owing at least in part to the lack of suitable in vivo models and the inability of cultured cells to recapitulate the complexity and structure associated with the gastrointestinal (GI) tract. Here, we report on the development of a three-dimensional (3-D) organotypic cell culture model of Caco-2 cells to model CVB infection of the gastrointestinal epithelium. We show that Caco-2 cells grown in 3-D using the rotating wall vessel (RWV) bioreactor recapitulate many of the properties of the intestinal epithelium, including the formation of well-developed tight junctions, apical-basolateral polarity, brush borders, and multicellular complexity. In addition, transcriptome analyses using transcriptome sequencing (RNA-Seq) revealed the induction of a number of genes associated with intestinal epithelial differentiation and/or intestinal processes in vivo when Caco-2 cells were cultured in 3-D. Applying this model to CVB infection, we found that although the levels of intracellular virus production were similar in two-dimensional (2-D) and 3-D Caco-2 cell cultures, the release of infectious CVB was enhanced in 3-D cultures at early stages of infection. Unlike CVB, the replication of poliovirus (PV) was significantly reduced in 3-D Caco-2 cell cultures. Collectively, our studies show that Caco-2 cells grown in 3-D using the RWV bioreactor provide a cell culture model that structurally and transcriptionally represents key aspects of cells in the human GI tract and can thus be used to expand our understanding of enterovirus-host interactions in intestinal epithelial cells. IMPORTANCE Coxsackievirus B (CVB), a member of the enterovirus family of RNA viruses, is associated with meningitis, pericarditis, diabetes, dilated cardiomyopathy, and myocarditis, among other pathologies. CVB is transmitted via the fecal-oral route and encounters the

  19. STAT3 noncell-autonomously controls planar cell polarity during zebrafish convergence and extension. (United States)

    Miyagi, Chiemi; Yamashita, Susumu; Ohba, Yusuke; Yoshizaki, Hisayoshi; Matsuda, Michiyuki; Hirano, Toshio


    Zebrafish signal transducer and activator of transcription 3 (STAT3) controls the cell movements during gastrulation. Here, we show that noncell-autonomous activity of STAT3 signaling in gastrula organizer cells controls the polarity of neighboring cells through Dishevelled-RhoA signaling in the Wnt-planar cell polarity (Wnt-PCP) pathway. In STAT3-depleted embryos, although all the known molecules in the Wnt-PCP pathway were expressed normally, the RhoA activity in lateral mesendodermal cells was down-regulated, resulting in severe cell polarization defects in convergence and extension movements identical to Strabismus-depleted embryos. Cell-autonomous activation of Wnt-PCP signaling by DeltaN-dishevelled rescued the defect in cell elongation, but not the orientation of lateral mesendodermal cells in STAT3-depleted embryos. The defect in the orientation could be rescued by transplantation of shield cells having noncell-autonomous activity of STAT3 signaling. These results suggest that the cells undergoing convergence and extension movement may sense the gradient of signaling molecules, which are expressed in gastrula organizer by STAT3 and noncell-autonomously activate PCP signaling in neighboring cells during zebrafish gastrulation.

  20. Cofilin and Vangl2 cooperate in the initiation of planar cell polarity in the mouse embryo. (United States)

    Mahaffey, James P; Grego-Bessa, Joaquim; Liem, Karel F; Anderson, Kathryn V


    The planar cell polarity (PCP; non-canonical Wnt) pathway is required to orient the cells within the plane of an epithelium. Here, we show that cofilin 1 (Cfl1), an actin-severing protein, and Vangl2, a core PCP protein, cooperate to control PCP in the early mouse embryo. Two aspects of planar polarity can be analyzed quantitatively at cellular resolution in the mouse embryo: convergent extension of the axial midline; and posterior positioning of cilia on cells of the node. Analysis of the spatial distribution of brachyury(+) midline cells shows that the Cfl1 mutant midline is normal, whereas Vangl2 mutants have a slightly wider midline. By contrast, midline convergent extension fails completely in Vangl2 Cfl1 double mutants. Planar polarity is required for the posterior positioning of cilia on cells in the mouse node, which is essential for the initiation of left-right asymmetry. Node cilia are correctly positioned in Cfl1 and Vangl2 single mutants, but cilia remain in the center of the cell in Vangl2 Cfl1 double mutants, leading to randomization of left-right asymmetry. In both the midline and node, the defect in planar polarity in the double mutants arises because PCP protein complexes fail to traffic to the apical cell membrane, although other aspects of apical-basal polarity are unaffected. Genetic and pharmacological experiments demonstrate that F-actin remodeling is essential for the initiation, but not maintenance, of PCP. We propose that Vangl2 and cofilin cooperate to target Rab11(+) vesicles containing PCP proteins to the apical membrane during the initiation of planar cell polarity.

  1. Iron repletion relocalizes hephaestin to a proximal basolateral compartment in polarized MDCK and Caco2 cells

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Seung-Min [Department of Biological Sciences, University of Columbia, NY (United States); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Attieh, Zouhair K. [Department of Laboratory Science and Technology, American University of Science and Technology, Ashrafieh (Lebanon); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Son, Hee Sook [Department of Food Science and Human Nutrition, College of Human Ecology, Chonbuk National University (Korea, Republic of); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Chen, Huijun [Medical School, Nanjing University, Nanjing 210008, Jiangsu Province (China); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Bacouri-Haidar, Mhenia [Department of Biology, Faculty of Sciences (I), Lebanese University, Hadath (Lebanon); Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States); Vulpe, Chris D., E-mail: [Department of Nutritional Science and Toxicology, University of California, Berkeley, CA (United States)


    Highlights: Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in non-polarized cells. Black-Right-Pointing-Pointer Hephaestin localizes in the perinuclear space in iron deficient and polarized cells. Black-Right-Pointing-Pointer Hephaestin with apical iron moves near to basolateral membrane of polarized cells. Black-Right-Pointing-Pointer Peri-basolateral location of hephaestin is accessible to the extracellular space. Black-Right-Pointing-Pointer Hephaestin is involved in iron mobilization from the intestine to circulation. -- Abstract: While intestinal cellular iron entry in vertebrates employs multiple routes including heme and non-heme routes, iron egress from these cells is exclusively channeled through the only known transporter, ferroportin. Reduced intestinal iron export in sex-linked anemia mice implicates hephaestin, a ferroxidase, in this process. Polarized cells are exposed to two distinct environments. Enterocytes contact the gut lumen via the apical surface of the cell, and through the basolateral surface, to the body. Previous studies indicate both local and systemic control of iron uptake. We hypothesized that differences in iron availability at the apical and/or basolateral surface may modulate iron uptake via cellular localization of hephaestin. We therefore characterized the localization of hephaestin in two models of polarized epithelial cell lines, MDCK and Caco2, with varying iron availability at the apical and basolateral surfaces. Our results indicate that hephaestin is expressed in a supra-nuclear compartment in non-polarized cells regardless of the iron status of the cells and in iron deficient and polarized cells. In polarized cells, we found that both apical (as FeSO{sub 4}) and basolateral iron (as the ratio of apo-transferrin to holo-transferrin) affect mobilization of hephaestin from the supra-nuclear compartment. We find that the presence of apical iron is essential for relocalization of hephaestin to a

  2. An on-chip study on the influence of geometrical confinement and chemical gradient on cell polarity. (United States)

    Zheng, Wenfu; Xie, Yunyan; Sun, Kang; Wang, Dong; Zhang, Yi; Wang, Chen; Chen, Yong; Jiang, Xingyu


    Cell polarity plays key roles in tissue development, regeneration, and pathological processes. However, how the cells establish and maintain polarity is still obscure so far. In this study, by employing microfluidic techniques, we explored the influence of geometrical confinement and chemical stimulation on the cell polarity and their interplay. We found that teardrop shape-induced anterior/posterior polarization of cells displayed homogeneous distribution of epidermal growth factor receptor, and the polarity could be maintained in a uniform epidermal growth factor (EGF) solution, but be broken by a reverse gradient of EGF, implying different mechanism of geometrical and chemical cue-induced cell polarity. Further studies indicated that a teardrop pattern could cause polarized distribution of microtubule-organization center and nucleus-Golgi complex, and this polarity was weakened when the cells were released from the confinement. Our study provides the evidence regarding the difference between geometrical and chemical cue-induced cell polarity and would be useful for understanding relationship between polarity and directional migration of cells.

  3. Polarization imaging and classification of Jurkat T and Ramos B cells using a flow cytometer. (United States)

    Feng, Yuanming; Zhang, Ning; Jacobs, Kenneth M; Jiang, Wenhuan; Yang, Li V; Li, Zhigang; Zhang, Jun; Lu, Jun Q; Hu, Xin-Hua


    Label-free and rapid classification of cells can have awide range of applications in biology. We report a robust method of polarization diffraction imaging flow cytometry (p-DIFC) for achieving this goal. Coherently scattered light signals are acquired from single cells excited by a polarized laser beam in the form of two cross-polarized diffraction images. Image texture and intensity parameters are extracted with a gray level co-occurrence matrix (GLCM) algorithm to obtain an optimized set of feature parameters as the morphological "fingerprints" for automated cell classification. We selected the Jurkat T cells and Ramos B cells to test the p-DIFC method's capacity for cell classification. After detailed statistical analysis, we found that the optimized feature vectors yield accuracies of classification between the Jurkat and Ramos ranging from 97.8% to 100% among different cell data sets. Confocal imaging and three-dimensional reconstruction were applied to gain insights on the ability of p-DIFC method for classifying the two cell lines of highly similar morphology. Based on these results we conclude that the p-DIFC method has the capacity to discriminate cells of high similarity in their morphology with "fingerprints" features extracted from the diffraction images, which may be attributed to subtle but statistically significant differences in the nucleus-to-cell volume ratio in the case of Jurkat and Ramos cells.

  4. Differential regulation of the Hippo pathway by adherens junctions and apical-basal cell polarity modules. (United States)

    Yang, Chih-Chao; Graves, Hillary K; Moya, Ivan M; Tao, Chunyao; Hamaratoglu, Fisun; Gladden, Andrew B; Halder, Georg


    Adherens junctions (AJs) and cell polarity complexes are key players in the establishment and maintenance of apical-basal cell polarity. Loss of AJs or basolateral polarity components promotes tumor formation and metastasis. Recent studies in vertebrate models show that loss of AJs or loss of the basolateral component Scribble (Scrib) cause deregulation of the Hippo tumor suppressor pathway and hyperactivation of its downstream effectors Yes-associated protein (YAP) and Transcriptional coactivator with PDZ-binding motif (TAZ). However, whether AJs and Scrib act through the same or independent mechanisms to regulate Hippo pathway activity is not known. Here, we dissect how disruption of AJs or loss of basolateral components affect the activity of the Drosophila YAP homolog Yorkie (Yki) during imaginal disc development. Surprisingly, disruption of AJs and loss of basolateral proteins produced very different effects on Yki activity. Yki activity was cell-autonomously decreased but non-cell-autonomously elevated in tissues where the AJ components E-cadherin (E-cad) or α-catenin (α-cat) were knocked down. In contrast, scrib knockdown caused a predominantly cell-autonomous activation of Yki. Moreover, disruption of AJs or basolateral proteins had different effects on cell polarity and tissue size. Simultaneous knockdown of α-cat and scrib induced both cell-autonomous and non-cell-autonomous Yki activity. In mammalian cells, knockdown of E-cad or α-cat caused nuclear accumulation and activation of YAP without overt effects on Scrib localization and vice versa. Therefore, our results indicate the existence of multiple, genetically separable inputs from AJs and cell polarity complexes into Yki/YAP regulation.

  5. Kruppel-like factor 4 regulates intestinal epithelial cell morphology and polarity.

    Directory of Open Access Journals (Sweden)

    Tianxin Yu

    Full Text Available Krüppel-like factor 4 (KLF4 is a zinc finger transcription factor that plays a vital role in regulating cell lineage differentiation during development and maintaining epithelial homeostasis in the intestine. In normal intestine, KLF4 is predominantly expressed in the differentiated epithelial cells. It has been identified as a tumor suppressor in colorectal cancer. KLF4 knockout mice demonstrated a decrease in number of goblet cells in the colon, and conditional ablation of KLF4 from the intestinal epithelium led to altered epithelial homeostasis. However, the role of KLF4 in differentiated intestinal cells and colon cancer cells, as well as the mechanism by which it regulates homeostasis and represses tumorigenesis in the intestine is not well understood. In our study, KLF4 was partially depleted in the differentiated intestinal epithelial cells by a tamoxifen-inducible Cre recombinase. We found a significant increase in the number of goblet cells in the KLF4-deleted small intestine, suggesting that KLF4 is not only required for goblet cell differentiation, but also required for maintaining goblet cell numbers through its function in inhibiting cell proliferation. The number and position of Paneth cells also changed. This is consistent with the KLF4 knockout study using villin-Cre [1]. Through immunohistochemistry (IHC staining and statistical analysis, we found that a stem cell and/or tuft cell marker, DCAMKL1, and a proliferation marker, Ki67, are affected by KLF4 depletion, while an enteroendocrine cell marker, neurotensin (NT, was not affected. In addition, we found KLF4 depletion altered the morphology and polarity of the intestinal epithelial cells. Using a three-dimensional (3D intestinal epithelial cyst formation assay, we found that KLF4 is essential for cell polarity and crypt-cyst formation in human colon cancer cells. These findings suggest that, as a tumor suppressor in colorectal cancer, KLF4 affects intestinal epithelial cell

  6. Monitoring the initiation and kinetics of human dendritic cell-induced polarization of autologous naive CD4+ T cells.

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    Tammy Oth

    Full Text Available A crucial step in generating de novo immune responses is the polarization of naive cognate CD4+ T cells by pathogen-triggered dendritic cells (DC. In the human setting, standardized DC-dependent systems are lacking to study molecular events during the initiation of a naive CD4+ T cell response. We developed a TCR-restricted assay to compare different pathogen-triggered human DC for their capacities to instruct functional differentiation of autologous, naive CD4+ T cells. We demonstrated that this methodology can be applied to compare differently matured DC in terms of kinetics, direction, and magnitude of the naive CD4+ T cell response. Furthermore, we showed the applicability of this assay to study the T cell polarizing capacity of low-frequency blood-derived DC populations directly isolated ex vivo. This methodology for addressing APC-dependent instruction of naive CD4+ T cells in a human autologous setting will provide researchers with a valuable tool to gain more insight into molecular mechanisms occurring in the early phase of T cell polarization. In addition, it may also allow the study of pharmacological agents on DC-dependent T cell polarization in the human system.

  7. Itinerant exosomes: emerging roles in cell and tissue polarity



    Cells use secreted signals (e.g. chemokines and growth factors) and sophisticated vehicles such as argosomes, cytonemes, tunneling nanotubes and exosomes to relay important information to other cells, often over large distances. Exosomes, 30–100-nm intraluminal vesicles of multivesicular bodies (MVB) released upon exocytic fusion of the MVB with the plasma membrane, are increasingly recognized as a novel mode of cell-independent communication. Exosomes have been shown to function in antigen p...

  8. Wnt5a functions in planar cell polarity regulation in mice. (United States)

    Qian, Dong; Jones, Chonnettia; Rzadzinska, Agnieszka; Mark, Sharayne; Zhang, Xiaohui; Steel, Karen P; Dai, Xing; Chen, Ping


    Planar cell polarity (PCP) refers to the polarization of cells within the plane of a cell sheet. A distinctive epithelial PCP in vertebrates is the uniform orientation of stereociliary bundles of the sensory hair cells in the mammalian cochlea. In addition to establishing epithelial PCP, planar polarization is also required for convergent extension (CE); a polarized cellular movement that occurs during neural tube closure and cochlear extension. Studies in Drosophila and vertebrates have revealed a conserved PCP pathway, including Frizzled (Fz) receptors. Here we use the cochlea as a model system to explore the involvement of known ligands of Fz, Wnt morphogens, in PCP regulation. We show that Wnt5a forms a reciprocal expression pattern with a Wnt antagonist, the secreted frizzled-related protein 3 (Sfrp3 or Frzb), along the axis of planar polarization in the cochlear epithelium. We further demonstrate that Wnt5a antagonizes Frzb in regulating cochlear extension and stereociliary bundle orientation in vitro, and that Wnt5a(-/-) animals have a shortened and widened cochlea. Finally, we show that Wnt5a is required for proper subcellular distribution of a PCP protein, Ltap/Vangl2, and that Wnt5a interacts genetically with Ltap/Vangl2 for uniform orientation of stereocilia, cochlear extension, and neural tube closure. Together, these findings demonstrate that Wnt5a functions in PCP regulation in mice.

  9. PTK7/CCK-4 is a novel regulator of planar cell polarity in vertebrates. (United States)

    Lu, Xiaowei; Borchers, Annette G M; Jolicoeur, Christine; Rayburn, Helen; Baker, Julie C; Tessier-Lavigne, Marc


    In addition to the apical-basal polarity pathway operating in epithelial cells, a planar cell polarity (PCP) pathway establishes polarity within the plane of epithelial tissues and is conserved from Drosophila to mammals. In Drosophila, a 'core' group of PCP genes including frizzled (fz), flamingo/starry night, dishevelled (dsh), Van Gogh/strabismus and prickle, function to regulate wing hair, bristle and ommatidial polarity. In vertebrates, the PCP pathway regulates convergent extension movements and neural tube closure, as well as the orientation of stereociliary bundles of sensory hair cells in the inner ear. Here we show that a mutation in the mouse protein tyrosine kinase 7 (PTK7) gene, which encodes an evolutionarily conserved transmembrane protein with tyrosine kinase homology, disrupts neural tube closure and stereociliary bundle orientation, and shows genetic interactions with a mutation in the mouse Van Gogh homologue vangl2. We also show that PTK7 is dynamically localized during hair cell polarization, and that the Xenopus homologue of PTK7 is required for neural convergent extension and neural tube closure. These results identify PTK7 as a novel regulator of PCP in vertebrates.

  10. Modeling of electrode polarization for electrolytic cells with a limited ionic adsorption. (United States)

    Sawada, Atsushi


    Dilute electrolytic cells filled with chlorobenzene containing small amounts of tetrabutylammonium tetraphenylborate show anomalous dielectric dispersions in low-frequency regions. We propose a new model for electrode polarization in order to analyze the dielectric behavior of the dilute electrolytic cells. The model comprises two capacitive components: One is the space-charge polarization accompanied with a specific ionic adsorption on electrodes, and the other is the electrode capacitance which is brought about by an electronic spillover from the electrode surface. This model can primarily explain the anomalous frequency-dependent dielectric behavior of the electrolytic cells not only with low electrolyte concentrations, but also with high concentrations and can correctly describe the characteristics of the electrode polarization reflected in the dielectric spectra.

  11. Vangl1 and Vangl2: planar cell polarity components with a developing role in cancer. (United States)

    Hatakeyama, Jason; Wald, Jessica H; Printsev, Ignat; Ho, Hsin-Yi Henry; Carraway, Kermit L


    Cancers commonly reactivate embryonic developmental pathways to promote the aggressive behavior of their cells, resulting in metastasis and poor patient outcome. While developmental pathways such as canonical Wnt signaling and epithelial-to-mesenchymal transition have received much attention, our understanding of the role of the planar cell polarity (PCP) pathway in tumor progression remains rudimentary. Protein components of PCP, including a subset that overlaps with the canonical Wnt pathway, partition in polarized epithelial cells along the planar axis and are required for the establishment and maintenance of lateral epithelial polarity. Significant insight into PCP regulation of developmental and cellular processes has come from analysis of the functions of the core PCP scaffolding proteins Vangl1 and Vangl2. In particular, studies on zebrafish and with Looptail (Lp) mice, which harbor point mutations in Vangl2 that alter its trafficking and localization, point to roles for the PCP pathway in maintaining cell polarization along both the apical-basal and planar axes as well as in collective cell motility and invasiveness. Recent findings have suggested that the Vangls can promote similar processes in tumor cells. Initial data-mining efforts suggest that VANGL1 and VANGL2 are dysregulated in human cancers, and estrogen receptor (ER)-positive breast cancer patients whose tumors exhibit elevated VANGL1 expression suffer from shortened overall survival. Overall, evidence is beginning to accumulate that the heightened cellular motility and invasiveness associated with PCP reactivation may contribute to the malignancy of some cancer subtypes.

  12. Mitotic Control of Planar Cell Polarity by Polo-like Kinase 1. (United States)

    Shrestha, Rezma; Little, Katherine A; Tamayo, Joel V; Li, Wenyang; Perlman, David H; Devenport, Danelle


    During cell division, polarized epithelial cells employ mechanisms to preserve cell polarity and tissue integrity. In dividing cells of the mammalian skin, planar cell polarity (PCP) is maintained through the bulk internalization, equal segregation, and polarized recycling of cortical PCP proteins. The dramatic redistribution of PCP proteins coincides precisely with cell-cycle progression, but the mechanisms coordinating PCP and mitosis are unknown. Here we identify Plk1 as a master regulator of PCP dynamics during mitosis. Plk1 interacts with core PCP component Celsr1 via a conserved polo-box domain (PBD)-binding motif, localizes to mitotic endosomes, and directly phosphorylates Celsr1. Plk1-dependent phosphorylation activates the endocytic motif specifically during mitosis, allowing bulk recruitment of Celsr1 into endosomes. Inhibiting Plk1 activity blocks PCP internalization and perturbs PCP asymmetry. Mimicking dileucine motif phosphorylation is sufficient to drive Celsr1 internalization during interphase. Thus, Plk1-mediated phosphorylation of Celsr1 ensures that PCP redistribution is precisely coordinated with mitotic entry.

  13. Polarization Curve of a Non-Uniformly Aged PEM Fuel Cell

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    Andrei Kulikovsky


    Full Text Available We develop a semi-analytical model for polarization curve of a polymer electrolyte membrane (PEM fuel cell with distributed (aged along the oxygen channel MEA transport and kinetic parameters of the membrane–electrode assembly (MEA. We show that the curve corresponding to varying along the channel parameter, in general, does not reduce to the curve for a certain constant value of this parameter. A possibility to determine the shape of the deteriorated MEA parameter along the oxygen channel by fitting the model equation to the cell polarization data is demonstrated.

  14. Mutation of the planar cell polarity gene VANGL1 in adolescent idiopathic scoliosis

    DEFF Research Database (Denmark)

    Andersen, Malene Rask; Farooq, Muhammad; Rasmussen, Karen Koefoed


    STUDY DESIGN: Mutation analysis of a candidate disease gene in a cohort of patients with moderate to severe Adolescent idiopathic scoliosis (AIS). OBJECTIVE: To investigate if damaging mutations in the planar cell polarity gene VANGL1 could be identified in AIS patients. SUMMARY OF BACKGROUND DATA......: AIS is a spinal deformity which occurs in 1-3% of the population. The cause of AIS is often unknown, but genetic factors are important in the etiology. Rare variants in genes encoding regulators of WNT/planar cell polarity (PCP) signaling were recently identified in AIS patients. METHODS: We analyzed...

  15. Unipolar membrane association of Dishevelled mediates Frizzled planar cell polarity signaling. (United States)

    Axelrod, J D


    Drosophila epithelia acquire a planar cell polarity (PCP) orthogonal to their apical-basal axes. Frizzled (Fz) is the receptor for the PCP signal, and Dishevelled (Dsh) transduces the signal. Here, I demonstrate that unipolar relocalization of Dsh to the membrane is required to mediate PCP, but not Wingless (Wg) signaling. Dsh membrane localization reflects the activation of Fz/PCP signaling, revealing that the initially symmetric signal evolves to one that displays unipolar asymmetry, specifying the cells' ultimate polarity. This transition from symmetric to asymmetric Dsh localization requires Dsh function, and reflects an amplification process that generates a steep intracellular activity gradient necessary to determine PCP.

  16. Rap1 integrates tissue polarity, lumen formation, and tumorigenicpotential in human breast epithelial cells

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Masahiko; Nelson, Celeste M.; Myers, Connie A.; Bissell,Mina J.


    Maintenance of apico-basal polarity in normal breast epithelial acini requires a balance between cell proliferation, cell death, and proper cell-cell and cell-extracellular matrix signaling. Aberrations in any of these processes can disrupt tissue architecture and initiate tumor formation. Here we show that the small GTPase Rap1 is a crucial element in organizing acinar structure and inducing lumen formation. Rap1 activity in malignant HMT-3522 T4-2 cells is appreciably higher than in S1 cells, their non-malignant counterparts. Expression of dominant-negative Rap1 resulted in phenotypic reversion of T4-2 cells, led to formation of acinar structures with correct apico-basal polarity, and dramatically reduced tumor incidence despite the persistence of genomic abnormalities. The resulting acini contained prominent central lumina not observed when other reverting agents were used. Conversely, expression of dominant-active Rap1 in T4-2 cells inhibited phenotypic reversion and led to increased invasiveness and tumorigenicity. Thus, Rap1 acts as a central regulator of breast architecture, with normal levels of activation instructing apical polarity during acinar morphogenesis, and increased activation inducing tumor formation and progression to malignancy.

  17. Neisseria gonorrhoeae breaches the apical junction of polarized epithelial cells for transmigration by activating EGFR. (United States)

    Edwards, Vonetta L; Wang, Liang-Chun; Dawson, Valerie; Stein, Daniel C; Song, Wenxia


    Neisseria gonorrhoeae initiates infection at the apical surface of columnar endocervical epithelial cells in the female reproductive tract. These cells provide a physical barrier against pathogens by forming continuous apical junctional complexes between neighbouring cells. This study examines the interaction of gonococci (GC) with polarized epithelial cells. We show that viable GC preferentially localize at the apical side of the cell-cell junction in polarized endometrial and colonic epithelial cells, HEC-1-B and T84. In GC-infected cells, continuous apical junctional complexes are disrupted, and the junction-associated protein β-catenin is redistributed from the apical junction to the cytoplasm and to GC adherent sites; however, overall cellular levels remain unchanged. This redistribution of junctional proteins is associated with a decrease in the 'fence' function of the apical junction but not its 'gate' function. Disruption of the apical junction by removing calcium increases GC transmigration across the epithelial monolayer. GC inoculation induces the phosphorylation of both epidermal growth factor receptor (EGFR) and β-catenin, while inhibition of EGFR kinase activity significantly reduces both GC-induced β-catenin redistribution and GC transmigration. Therefore, the gonococcus is capable of weakening the apical junction and polarity of epithelial cells by activating EGFR, which facilitates GC transmigration across the epithelium.

  18. Pressure Dependent Wall Relaxation in Polarized $^3$He Gaseous Cells

    CERN Document Server

    Peng, C; Chu, P -H; Gao, H; Zhang, Y


    Pressure dependence of longitudinal relaxation time (T$_1$) due to the cell wall was observed previously at both room temperature and low temperature in valved Rb-coated refillable $^3$He gaseous cells in \\cite{Zheng2}. The diffusion of $^3$He from measurement cell through a capillary tube to the valve and the subsequent depolarization on the surface of the valve was proposed to possibly explain such a pressure dependence at room temperature \\cite{Saam}. In this paper, we investigate this diffusion effect through measurements of T$_1$ with newly designed Rb-coated Pyrex glass cells at 295 K as well as finite element analysis (FEA) studies. Both the experimental results and FEA studies show that the diffusion effect is insufficient to explain the observed linear pressure-dependent behavior of T$_1$.

  19. A combined binary interaction and phenotypic map of C. elegans cell polarity proteins (United States)

    Koorman, Thijs; Lemmens, Irma; Ramalho, João J.; Nieuwenhuize, Susan; van den Heuvel, Sander; Tavernier, Jan; Nance, Jeremy; Boxem, Mike


    The establishment of cell polarity is an essential process for the development of multicellular organisms and the functioning of cells and tissues. Here, we combine large-scale protein interaction mapping with systematic phenotypic profiling to study the network of physical interactions that underlies polarity establishment and maintenance in the nematode Caenorhabditis elegans. Using a fragment-based yeast two-hybrid strategy, we identified 439 interactions between 296 proteins, as well as the protein regions that mediate these interactions. Phenotypic profiling of the network resulted in the identification of 100 physically interacting protein pairs for which RNAi-mediated depletion caused a defect in the same polarity-related process. We demonstrate the predictive capabilities of the network by showing that the physical interaction between the RhoGAP PAC-1 and PAR-6 is required for radial polarization of the C. elegans embryo. Our network represents a valuable resource of candidate interactions that can be used to further our insight into cell polarization. PMID:26780296

  20. Two small GTPases act in concert with the bactofilin cytoskeleton to regulate dynamic bacterial cell polarity. (United States)

    Bulyha, Iryna; Lindow, Steffi; Lin, Lin; Bolte, Kathrin; Wuichet, Kristin; Kahnt, Jörg; van der Does, Chris; Thanbichler, Martin; Søgaard-Andersen, Lotte


    Cell polarity is essential for many bacterial activities, but the mechanisms responsible for its establishment are poorly understood. In Myxococcus xanthus, the type IV pili (T4P) motor ATPases PilB and PilT localize to opposite cell poles and switch poles during cellular reversals. We demonstrate that polar localization of PilB and PilT depends on the small GTPase SofG and BacP, a bactofilin cytoskeletal protein. Polymeric BacP localizes in both subpolar regions. SofG interacts directly with polymeric BacP and associates with one of these patches, forming a cluster that shuttles to the pole to establish localization of PilB and PilT at the same pole. Next, the small GTPase MglA sorts PilB and PilT to opposite poles to establish their correct polarity. During reversals, the Frz chemosensory system induces the inversion of PilB and PilT polarity. Thus, three hierarchically organized systems function in a cascade to regulate dynamic bacterial cell polarity.

  1. The planar cell polarity effector protein Wdpcp (Fritz) controls epithelial cell cortex dynamics via septins and actomyosin. (United States)

    Park, Tae Joo; Kim, Su Kyoung; Wallingford, John B


    Planar cell polarity (PCP) signaling controls polarized behaviors in diverse tissues, including the collective cell movements of gastrulation and the planar polarized beating of motile cilia. A major question in PCP signaling concerns the mechanisms linking this signaling cascade with more general cytoskeletal elements to drive polarized behavior. Previously, we reported that the PCP effector protein Wdpcp (formerly known as Fritz) interacts with septins and is critical for collective cell migration and cilia formation. Here, we report that Wdpcp is broadly involved in maintaining cortical tension in epithelial cells. In vivo 3D time-lapse imaging revealed that Wdpcp is necessary for basolateral plasma membrane stability in epithelial tissues, and we further show that Wdpcp controls cortical septin localization to maintain cortical rigidity in mucociliary epithelial cells. Finally, we show that Wdpcp acts via actomyosin to maintain balanced cortical tension in the epithelium. These data suggest that, in addition to its role in controlling plasma membrane dynamics in collective mesenchymal cell movements, Wdpcp is also essential for normal cell cortex stability during epithelial homeostasis.

  2. Bazooka/PAR3 is dispensable for polarity in Drosophila follicular epithelial cells

    Directory of Open Access Journals (Sweden)

    Jaffer Shahab


    Full Text Available Apico-basal polarity is the defining characteristic of epithelial cells. In Drosophila, apical membrane identity is established and regulated through interactions between the highly conserved Par complex (Bazooka/Par3, atypical protein kinase C and Par6, and the Crumbs complex (Crumbs, Stardust and PATJ. It has been proposed that Bazooka operates at the top of a genetic hierarchy in the establishment and maintenance of apico-basal polarity. However, there is still ambiguity over the correct sequence of events and cross-talk with other pathways during this process. In this study, we reassess this issue by comparing the phenotypes of the commonly used baz4 and baz815-8 alleles with those of the so far uncharacterized bazXR11 and bazEH747 null alleles in different Drosophila epithelia. While all these baz alleles display identical phenotypes during embryonic epithelial development, we observe strong discrepancies in the severity and penetrance of polarity defects in the follicular epithelium: polarity is mostly normal in bazEH747 and bazXR11 while baz4 and baz815-8 show loss of polarity, severe multilayering and loss of epithelial integrity throughout the clones. Further analysis reveals that the chromosomes carrying the baz4 and baz815-8 alleles may contain additional mutations that enhance the true baz loss-of-function phenotype in the follicular epithelium. This study clearly shows that Baz is dispensable for the regulation of polarity in the follicular epithelium, and that the requirement for key regulators of cell polarity is highly dependent on developmental context and cell type.

  3. Bazooka/PAR3 is dispensable for polarity in Drosophila follicular epithelial cells. (United States)

    Shahab, Jaffer; Tiwari, Manu D; Honemann-Capito, Mona; Krahn, Michael P; Wodarz, Andreas


    Apico-basal polarity is the defining characteristic of epithelial cells. In Drosophila, apical membrane identity is established and regulated through interactions between the highly conserved Par complex (Bazooka/Par3, atypical protein kinase C and Par6), and the Crumbs complex (Crumbs, Stardust and PATJ). It has been proposed that Bazooka operates at the top of a genetic hierarchy in the establishment and maintenance of apico-basal polarity. However, there is still ambiguity over the correct sequence of events and cross-talk with other pathways during this process. In this study, we reassess this issue by comparing the phenotypes of the commonly used baz(4) and baz(815-8) alleles with those of the so far uncharacterized baz(XR11) and baz(EH747) null alleles in different Drosophila epithelia. While all these baz alleles display identical phenotypes during embryonic epithelial development, we observe strong discrepancies in the severity and penetrance of polarity defects in the follicular epithelium: polarity is mostly normal in baz(EH747) and baz(XR11) while baz(4) and baz(815) (-8) show loss of polarity, severe multilayering and loss of epithelial integrity throughout the clones. Further analysis reveals that the chromosomes carrying the baz(4) and baz(815-8) alleles may contain additional mutations that enhance the true baz loss-of-function phenotype in the follicular epithelium. This study clearly shows that Baz is dispensable for the regulation of polarity in the follicular epithelium, and that the requirement for key regulators of cell polarity is highly dependent on developmental context and cell type.

  4. Trophoblast glycoprotein promotes pancreatic ductal adenocarcinoma cell metastasis through Wnt/planar cell polarity signaling. (United States)

    He, Ping; Jiang, Shuheng; Ma, Mingze; Wang, Yang; Li, Rongkun; Fang, Fang; Tian, Guangang; Zhang, Zhigang


    Trophoblast glycoprotein (TPBG), a 72 kDa glycoprotein was identified using a monoclonal antibody, which specifically binds human trophoblast. The expression of TPBG in normal tissues is limited; however, it is upregulated in numerous types of cancer. When TPBG is expressed at a high level, this usually indicates a poor clinical outcome. In the present study, it was demonstrated that TPBG was more commonly observed in human pancreatic ductal adenocarcinoma (PDAC) compared with normal pancreatic tissue. Immunohistochemical analysis of PDAC tissue microarrays indicated that the expression of TPBG in PDAC tissues was closely correlated with the tumor-node-metastasis stage of the tumor. Silencing of TPBG in PDAC cell lines resulted in a decreased ability of cancer cell migration and invasion. Further investigation demonstrated that the Wnt/planar cell polarity signaling pathway was suppressed, as the expression of Wnt5a and the activation of c-Jun N-terminal kinase was inhibited following TPBG knockdown. In conclusion, the present study provided evidence that TPBG is involved in PDAC metastasis, and that TPBG and its associated signaling pathways may be a suitable target for PDAC therapy.

  5. Polarity and cell division orientation in the cleavage embryo: from worm to human (United States)

    Ajduk, Anna; Zernicka-Goetz, Magdalena


    Cleavage is a period after fertilization, when a 1-cell embryo starts developing into a multicellular organism. Due to a series of mitotic divisions, the large volume of a fertilized egg is divided into numerous smaller, nucleated cells—blastomeres. Embryos of different phyla divide according to different patterns, but molecular mechanism of these early divisions remains surprisingly conserved. In the present paper, we describe how polarity cues, cytoskeleton and cell-to-cell communication interact with each other to regulate orientation of the early embryonic division planes in model animals such as Caenorhabditis elegans, Drosophila and mouse. We focus particularly on the Par pathway and the actin-driven cytoplasmic flows that accompany it. We also describe a unique interplay between Par proteins and the Hippo pathway in cleavage mammalian embryos. Moreover, we discuss the potential meaning of polarity, cytoplasmic dynamics and cell-to-cell communication as quality biomarkers of human embryos. PMID:26660321

  6. IKKα Promotes Intestinal Tumorigenesis by Limiting Recruitment of M1-like Polarized Myeloid Cells

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    Serkan I. Göktuna


    Full Text Available The recruitment of immune cells into solid tumors is an essential prerequisite of tumor development. Depending on the prevailing polarization profile of these infiltrating leucocytes, tumorigenesis is either promoted or blocked. Here, we identify IκB kinase α (IKKα as a central regulator of a tumoricidal microenvironment during intestinal carcinogenesis. Mice deficient in IKKα kinase activity are largely protected from intestinal tumor development that is dependent on the enhanced recruitment of interferon γ (IFNγ-expressing M1-like myeloid cells. In IKKα mutant mice, M1-like polarization is not controlled in a cell-autonomous manner but, rather, depends on the interplay of both IKKα mutant tumor epithelia and immune cells. Because therapies aiming at the tumor microenvironment rather than directly at the mutated cancer cell may circumvent resistance development, we suggest IKKα as a promising target for colorectal cancer (CRC therapy.

  7. Requirement for Dlgh-1 in planar cell polarity and skeletogenesis during vertebrate development.

    Directory of Open Access Journals (Sweden)

    Charlene Rivera

    Full Text Available The development of specialized organs is tightly linked to the regulation of cell growth, orientation, migration and adhesion during embryogenesis. In addition, the directed movements of cells and their orientation within the plane of a tissue, termed planar cell polarity (PCP, appear to be crucial for the proper formation of the body plan. In Drosophila embryogenesis, Discs large (dlg plays a critical role in apical-basal cell polarity, cell adhesion and cell proliferation. Craniofacial defects in mice carrying an insertional mutation in Dlgh-1 suggest that Dlgh-1 is required for vertebrate development. To determine what roles Dlgh-1 plays in vertebrate development, we generated mice carrying a null mutation in Dlgh-1. We found that deletion of Dlgh-1 caused open eyelids, open neural tube, and misorientation of cochlear hair cell stereociliary bundles, indicative of defects in planar cell polarity (PCP. Deletion of Dlgh-1 also caused skeletal defects throughout the embryo. These findings identify novel roles for Dlgh-1 in vertebrates that differ from its well-characterized roles in invertebrates and suggest that the Dlgh-1 null mouse may be a useful animal model to study certain human congenital birth defects.

  8. Requirement for Dlgh-1 in planar cell polarity and skeletogenesis during vertebrate development. (United States)

    Rivera, Charlene; Simonson, Sara J S; Yamben, Idella F; Shatadal, Shalini; Nguyen, Minh M; Beurg, Maryline; Lambert, Paul F; Griep, Anne E


    The development of specialized organs is tightly linked to the regulation of cell growth, orientation, migration and adhesion during embryogenesis. In addition, the directed movements of cells and their orientation within the plane of a tissue, termed planar cell polarity (PCP), appear to be crucial for the proper formation of the body plan. In Drosophila embryogenesis, Discs large (dlg) plays a critical role in apical-basal cell polarity, cell adhesion and cell proliferation. Craniofacial defects in mice carrying an insertional mutation in Dlgh-1 suggest that Dlgh-1 is required for vertebrate development. To determine what roles Dlgh-1 plays in vertebrate development, we generated mice carrying a null mutation in Dlgh-1. We found that deletion of Dlgh-1 caused open eyelids, open neural tube, and misorientation of cochlear hair cell stereociliary bundles, indicative of defects in planar cell polarity (PCP). Deletion of Dlgh-1 also caused skeletal defects throughout the embryo. These findings identify novel roles for Dlgh-1 in vertebrates that differ from its well-characterized roles in invertebrates and suggest that the Dlgh-1 null mouse may be a useful animal model to study certain human congenital birth defects.

  9. Dielectric process of space-charge polarization for an electrolytic cell with blocking electrodes. (United States)

    Sawada, Atsushi


    The dielectric process of space-charge polarization for an electrolytic cell with blocking electrodes is simulated considering bound charges externally supplied to the electrodes. A numerical calculation is performed to determine the distribution of mobile charges under an ac field satisfying Poisson's equation in which the dielectric constant varies with frequency. An exact frequency-dependent curve of the complex dielectric constant is obtained by including the contribution of bound charges induced by the space-charge polarization itself in Poisson's equation at every frequency. The present model of the space-charge polarization enables one to correctly understand the experimental results on the complex dielectric constant of electrolytic cells in low-frequency regions.

  10. An integrin-ILK-microtubule network orients cell polarity and lumen formation in glandular epithelium. (United States)

    Akhtar, Nasreen; Streuli, Charles H


    The extracellular matrix has a crucial role in determining the spatial orientation of epithelial polarity and the formation of lumens in glandular tissues; however, the underlying mechanisms remain elusive. By using Cre–Lox deletion we show that β1 integrins are required for normal mammary gland morphogenesis and lumen formation, both in vivo and in a three-dimensional primary culture model in which epithelial cells directly contact a basement membrane. Downstream of basement membrane β1 integrins, Rac1 is not involved; however, ILK is needed to polarize microtubule plus ends at the basolateral membrane and disrupting each of these components prevents lumen formation. The integrin–microtubule axis is necessary for the endocytic removal of apical proteins from the basement-membrane–cell interface and for internal Golgi positioning. We propose that this integrin signalling network controls the delivery of apical components to the correct surface and thereby governs the orientation of polarity and development of lumens.

  11. The planar cell polarity protein Strabismus promotes Pins anterior localization during asymmetric division of sensory organ precursor cells in Drosophila. (United States)

    Bellaïche, Yohanns; Beaudoin-Massiani, Olivia; Stuttem, Isabella; Schweisguth, François


    Cell fate diversity is generated in part by the unequal segregation of cell-fate determinants during asymmetric cell division. In the Drosophila bristle lineage, the sensory organ precursor (pI) cell is polarized along the anteroposterior (AP) axis by Frizzled (Fz) receptor signaling. We show here that Fz localizes at the posterior apical cortex of the pI cell prior to mitosis, whereas Strabismus (Stbm) and Prickle (Pk), which are also required for AP polarization of the pI cell, co-localize at the anterior apical cortex. Thus, asymmetric localization of Fz, Stbm and Pk define two opposite cortical domains prior to mitosis of the pI cell. At mitosis, Stbm forms an anterior crescent that overlaps with the distribution of Partner of Inscuteable (Pins) and Discs-large (Dlg), two components of the anterior Dlg-Pins-Galphai complex that regulates the localization of cell-fate determinants. At prophase, Stbm promotes the anterior localization of Pins. By contrast, Dishevelled (Dsh) acts antagonistically to Stbm by excluding Pins from the posterior cortex. We propose that the Stbm-dependent recruitment of Pins at the anterior cortex of the pI cell is a novel read-out of planar cell polarity.

  12. The Rho GTPase Cdc42 regulates hair cell planar polarity and cellular patterning in the developing cochlea. (United States)

    Kirjavainen, Anna; Laos, Maarja; Anttonen, Tommi; Pirvola, Ulla


    Hair cells of the organ of Corti (OC) of the cochlea exhibit distinct planar polarity, both at the tissue and cellular level. Planar polarity at tissue level is manifested as uniform orientation of the hair cell stereociliary bundles. Hair cell intrinsic polarity is defined as structural hair bundle asymmetry; positioning of the kinocilium/basal body complex at the vertex of the V-shaped bundle. Consistent with strong apical polarity, the hair cell apex displays prominent actin and microtubule cytoskeletons. The Rho GTPase Cdc42 regulates cytoskeletal dynamics and polarization of various cell types, and, thus, serves as a candidate regulator of hair cell polarity. We have here induced Cdc42 inactivation in the late-embryonic OC. We show the role of Cdc42 in the establishment of planar polarity of hair cells and in cellular patterning. Abnormal planar polarity was displayed as disturbances in hair bundle orientation and morphology and in kinocilium/basal body positioning. These defects were accompanied by a disorganized cell-surface microtubule network. Atypical protein kinase C (aPKC), a putative Cdc42 effector, colocalized with Cdc42 at the hair cell apex, and aPKC expression was altered upon Cdc42 depletion. Our data suggest that Cdc42 together with aPKC is part of the machinery establishing hair cell planar polarity and that Cdc42 acts on polarity through the cell-surface microtubule network. The data also suggest that defects in apical polarization are influenced by disturbed cellular patterning in the OC. In addition, our data demonstrates that Cdc42 is required for stereociliogenesis in the immature cochlea.

  13. Role of extracellular cations in cell motility, polarity, and chemotaxis

    Directory of Open Access Journals (Sweden)

    Soll D


    Full Text Available David R Soll1, Deborah Wessels1, Daniel F Lusche1, Spencer Kuhl1, Amanda Scherer1, Shawna Grimm1,21Monoclonal Antibody Research Institute, Developmental Studies, Hybridoma Bank, Department of Biology, University of Iowa, Iowa City; 2Mercy Medical Center, Surgical Residency Program, Des Moines, Iowa, USAAbstract: The concentration of cations in the aqueous environment of free living organisms and cells within the human body influence motility, shape, and chemotaxis. The role of extracellular cations is usually perceived to be the source for intracellular cations in the process of homeostasis. The role of surface molecules that interact with extracellular cations is believed to be that of channels, transporters, and exchangers. However, the role of Ca2+ as a signal and chemoattractant and the discovery of the Ca2+ receptor have demonstrated that extracellular cations can function as signals at the cell surface, and the plasma membrane molecules they interact with can function as bona fide receptors that activate coupled signal transduction pathways, associated molecules in the plasma membrane, or the cytoskeleton. With this perspective in mind, we have reviewed the cationic composition of aqueous environments of free living cells and cells that move in multicellular organisms, most notably humans, the range of molecules interacting with cations at the cell surface, the concept of a cell surface cation receptor, and the roles extracellular cations and plasma membrane proteins that interact with them play in the regulation of motility, shape, and chemotaxis. Hopefully, the perspective of this review will increase awareness of the roles extracellular cations play and the possibility that many of the plasma membrane proteins that interact with them could also play roles as receptors.Keywords: extracellular cations, chemotaxis, transporters, calcium, receptors

  14. Planar Cell Polarity Breaks the Symmetry of PAR Protein Distribution prior to Mitosis in Drosophila Sensory Organ Precursor Cells. (United States)

    Besson, Charlotte; Bernard, Fred; Corson, Francis; Rouault, Hervé; Reynaud, Elodie; Keder, Alyona; Mazouni, Khalil; Schweisguth, François


    During development, cell-fate diversity can result from the unequal segregation of fate determinants at mitosis. Polarization of the mother cell is essential for asymmetric cell division (ACD). It often involves the formation of a cortical domain containing the PAR complex proteins Par3, Par6, and atypical protein kinase C (aPKC). In the fly notum, sensory organ precursor cells (SOPs) divide asymmetrically within the plane of the epithelium and along the body axis to generate two distinct cells. Fate asymmetry depends on the asymmetric localization of the PAR complex. In the absence of planar cell polarity (PCP), SOPs divide with a random planar orientation but still asymmetrically, showing that PCP is dispensable for PAR asymmetry at mitosis. To study when and how the PAR complex localizes asymmetrically, we have used a quantitative imaging approach to measure the planar polarization of the proteins Bazooka (Baz, fly Par3), Par6, and aPKC in living pupae. By using imaging of functional GFP-tagged proteins with image processing and computational modeling, we find that Baz, Par6, and aPKC become planar polarized prior to mitosis in a manner independent of the AuroraA kinase and that PCP is required for the planar polarization of Baz, Par6, and aPKC during interphase. This indicates that a "mitosis rescue" mechanism establishes asymmetry at mitosis in PCP mutants. This study therefore identifies PCP as the initial symmetry-breaking signal for the planar polarization of PAR proteins in asymmetrically dividing SOPs.

  15. Dynamics of planar cell polarity protein Vangl2 in the mouse oviduct epithelium. (United States)

    Shi, Dongbo; Usami, Fumiko; Komatsu, Kouji; Oka, Sanae; Abe, Takaya; Uemura, Tadashi; Fujimori, Toshihiko


    The planar cell polarity (PCP) pathway regulates morphogenesis in various organs. The polarized localization is a key feature of core PCP factors for orchestrating cell polarity in an epithelial sheet. Several studies using Drosophila melanogaster have investigated the mechanism of the polarized localization. However, to what extent these mechanisms are conserved and how the polarization of core PCP factors is maintained in mature vertebrates are still open questions. Here, we addressed these questions by analyzing the dynamics of Vangl2, a member of core PCP factors, in the mouse oviduct epithelium. Multiple core PCP factors including Vangl2 were expressed in the mouse oviduct in postnatal stages. Vangl1, Vangl2 and Frizzled6 had polarized localization in the oviduct epithelium. Exogenously introduced expression of green fluorescent protein (GFP)-tagged core PCP factors by electroporation revealed that Vangl1, Vangl2 and Prickle2 are localized on the ovarian side of the cell periphery in the oviduct. To visualize the Vangl2 dynamics, we generated the R26-Vangl2-EGFP transgenic mice. In these mice, Vangl2-EGFP was ubiquitously expressed and showed polarized localization in multiple organs including the oviduct, the trachea, the lateral ventricle and the uterus. Fluorescence recovery after photobleaching (FRAP) analysis in the mature oviduct revealed that Vangl2 in the enriched subdomain of cell periphery (cellular edge) was more stable than Vangl2 in the less-enriched cellular edge. Furthermore, when a subregion of a Vangl2-enriched cellular edge was bleached, the Vangl2-enriched subregion neighboring the bleached region in the same cellular edge tended to decrease more intensities than the neighboring sub-region in the next Vangl2-enriched cellular edge. Finally, the polarization of Vangl2 was observed in nocodazole treated mouse viduct, suggesting the maintenance of Vangl2 asymmetry is independent of microtubule formation. Taken together, we revealed the

  16. The planar cell polarity pathway in vertebrate development

    NARCIS (Netherlands)

    Wansleeben, C.; Meijlink, F.


    Directing the orientation of cells in three dimensions is a fundamental aspect of many of the processes underlying the generation of the appropriate shape and function of tissues and organs during embryonic development. In an epithelium, this requires not only the establishment of apicobasal polarit

  17. FGF signaling regulates Wnt ligand expression to control vulval cell lineage polarity in C. elegans. (United States)

    Minor, Paul J; He, Ting-Fang; Sohn, Chang Ho; Asthagiri, Anand R; Sternberg, Paul W


    The interpretation of extracellular cues leading to the polarization of intracellular components and asymmetric cell divisions is a fundamental part of metazoan organogenesis. The Caenorhabditis elegans vulva, with its invariant cell lineage and interaction of multiple cell signaling pathways, provides an excellent model for the study of cell polarity within an organized epithelial tissue. Here, we show that the fibroblast growth factor (FGF) pathway acts in concert with the Frizzled homolog LIN-17 to influence the localization of SYS-1, a component of the Wnt/β-catenin asymmetry pathway, indirectly through the regulation of cwn-1. The source of the FGF ligand is the primary vulval precursor cell (VPC) P6.p, which controls the orientation of the neighboring secondary VPC P7.p by signaling through the sex myoblasts (SMs), activating the FGF pathway. The Wnt CWN-1 is expressed in the posterior body wall muscle of the worm as well as in the SMs, making it the only Wnt expressed on the posterior and anterior sides of P7.p at the time of the polarity decision. Both sources of cwn-1 act instructively to influence P7.p polarity in the direction of the highest Wnt signal. Using single molecule fluorescence in situ hybridization, we show that the FGF pathway regulates the expression of cwn-1 in the SMs. These results demonstrate an interaction between FGF and Wnt in C. elegans development and vulval cell lineage polarity, and highlight the promiscuous nature of Wnts and the importance of Wnt gradient directionality within C. elegans.

  18. Different populations of Wnt-containing vesicles are individually released from polarized epithelial cells (United States)

    Chen, Qiuhong; Takada, Ritsuko; Noda, Chiyo; Kobayashi, Satoru; Takada, Shinji


    Accumulating evidence suggests that exosomes are heterogeneous in molecular composition and physical properties. Here we examined whether epithelial cells secrete a heterogeneous population of exosomes, and if that is the case, whether epithelial cell polarity affects release of different populations of exosomes, especially that of those carrying Wnt. Sucrose-density ultracentrifugation and molecular marker analysis revealed that different populations of exosomes or exosome-like vesicles were released from MDCK cells depending on the cell polarity. Wnt3a associated with these vesicles were detectable in culture media collected from both apical and basolateral sides of the cells. Basolaterally secreted Wnt3a were co-fractionated with a typical exosomal protein TSG101 in fractions having typical exosome densities. In contrast, most of apically secreted Wnt3a, as well as Wnt11, were co-fractionated with CD63 and Hsp70, which are also common to the most exosomes, but recovered in higher density fractions. Wnt3a exhibiting similar floatation behavior to the apically secreted ones were also detectable in the culture media of Wnt3a-expressing L and HEK293 cells. The lipidation of Wnt3a was required for its basolateral secretion in exosomes but was dispensable for the apical one. Thus, epithelial cells release Wnt via distinct populations of vesicles differing in secretion polarity and lipidation dependency. PMID:27765945

  19. The hippo pathway promotes Notch signaling in regulation of cell differentiation, proliferation, and oocyte polarity.

    Directory of Open Access Journals (Sweden)

    Jianzhong Yu

    Full Text Available Specification of the anterior-posterior axis in Drosophila oocytes requires proper communication between the germ-line cells and the somatically derived follicular epithelial cells. Multiple signaling pathways, including Notch, contribute to oocyte polarity formation by controlling the temporal and spatial pattern of follicle cell differentiation and proliferation. Here we show that the newly identified Hippo tumor-suppressor pathway plays a crucial role in the posterior follicle cells in the regulation of oocyte polarity. Disruption of the Hippo pathway, including major components Hippo, Salvador, and Warts, results in aberrant follicle-cell differentiation and proliferation and dramatic disruption of the oocyte anterior-posterior axis. These phenotypes are related to defective Notch signaling in follicle cells, because misexpression of a constitutively active form of Notch alleviates the oocyte polarity defects. We also find that follicle cells defective in Hippo signaling accumulate the Notch receptor and display defects in endocytosis markers. Our findings suggest that the interaction between Hippo and classic developmental pathways such as Notch is critical to spatial and temporal regulation of differentiation and proliferation and is essential for development of the body axes in Drosophila.

  20. A biomechanical model for cell polarization and intercalation during Drosophila germband extension (United States)

    Lan, Haihan; Wang, Qiming; Fernandez-Gonzalez, Rodrigo; Feng, James J.


    Germband extension during Drosophila development features the merging of cells along the dorsal-ventral (DV) axis and their separation along the anterior-posterior (AP) axis. This intercalation process involves planar cell polarity, anisotropic contractile forces along cell edges, and concerted cell deformation and movement. Although prior experiments have probed each of these factors separately, the connection among them remains unclear. This paper presents a chemo-mechanical model that integrates the three factors into a coherent framework. The model predicts the polarization of Rho-kinase, myosin and Bazooka downstream of an anisotropic Shroom distribution. In particular, myosin accumulates on cell edges along the DV axis, causing them to contract into a vertex. Subsequently, medial myosin in the cells anterior and posterior to the vertex helps to elongate it into a new edge parallel to the body axis. Thus, the tissue extends along the AP axis and narrows in the transverse direction through neighbor exchange. Model predictions of the polarity of the proteins and cell and tissue deformation are in good agreement with experimental observations.

  1. The young and happy marriage of membrane traffic and cell polarity. (United States)

    Thompson, Barry J; Perez, Franck; Vaccari, Thomas


    The ESF-EMBO meeting on 'Cell Polarity and Membrane Traffic' took place in Poland in April 2012. It brought together scientists from two once separate fields and highlighted their emerging interdependence. The wealth of scientific insights and discoveries presented laid a path for future research.

  2. Dystroglycan is required for polarizing the epithelial cells and the oocyte in Drosophila

    DEFF Research Database (Denmark)

    Deng, Wu-Min; Schneider, Martina; Frock, Richard;


    The transmembrane protein Dystroglycan is a central element of the dystrophin-associated glycoprotein complex, which is involved in the pathogenesis of many forms of muscular dystrophy. Dystroglycan is a receptor for multiple extracellular matrix (ECM) molecules such as Laminin, agrin and perleca......, possibly by organizing the Laminin ECM. These data suggest that the primary function of Dystroglycan in oogenesis is to organize cellular polarity; and this study sets the stage for analyzing the Dystroglycan complex by using the power of Drosophila molecular genetics......., and plays a role in linking the ECM to the actin cytoskeleton; however, how these interactions are regulated and their basic cellular functions are poorly understood. Using mosaic analysis and RNAi in the model organism Drosophila melanogaster, we show that Dystroglycan is required cell......-autonomously for cellular polarity in two different cell types, the epithelial cells (apicobasal polarity) and the oocyte (anteroposterior polarity). Loss of Dystroglycan function in follicle and disc epithelia results in expansion of apical markers to the basal side of cells and overexpression results in a reduced apical...

  3. Effect of Polarization on Airway Epithelial Conditioning of Monocyte-Derived Dendritic Cells

    DEFF Research Database (Denmark)

    Papazian, Dick; Chhoden, Tashi; Arge, Maria


    to sample allergens administered to the apical side. Allergen uptake depended on both polarization and the nature of the allergen. AEC conditioning led to decreased birch allergen-specific proliferation of autologous T cells and a trend toward decreased secretion of the Th2-specific cytokines IL-5 and IL-13...

  4. Mathematical modeling of planar cell polarity signaling in the Drosophila melanogaster wing (United States)

    Amonlirdviman, Keith

    Planar cell polarity (PCP) signaling refers to the coordinated polarization of cells within the plane of various epithelial tissues to generate sub-cellular asymmetry along an axis orthogonal to their apical-basal axes. For example, in the Drosophila wing, PCP is seen in the parallel orientation of hairs that protrude from each of the approximately 30,000 epithelial cells to robustly point toward the wing tip. Through a poorly understood mechanism, cell clones mutant for some PCP signaling components, including some, but not all alleles of the receptor frizzled, cause polarity disruptions of neighboring, wild-type cells, a phenomenon referred to as domineering nonautonomy. Previous models have proposed diffusible factors to explain nonautonomy, but no such factors have yet been found. This dissertation describes the mathematical modeling of PCP in the Drosophila wing, based on a contact dependent signaling hypothesis derived from experimental results. Intuition alone is insufficient to deduce that this hypothesis, which relies on a local feedback loop acting at the cell membrane, underlies the complex patterns observed in large fields of cells containing mutant clones, and others have argued that it cannot account for observed phenotypes. Through reaction-diffusion, partial differential equation modeling and simulation, the feedback loop is shown to fully reproduce PCP phenotypes, including domineering nonautonomy. The sufficiency of this model and the experimental validation of model predictions argue that previously proposed diffusible factors need not be invoked to explain PCP signaling and reveal how specific protein-protein interactions lead to autonomy or domineering nonautonomy. Based on these results, an ordinary differential equation model is derived to study the relationship of the feedback loop with upstream signaling components. The cadherin Fat transduces a cue to the local feedback loop, biasing the polarity direction of each cell toward the wing tip

  5. Eya1 controls cell polarity, spindle orientation, cell fate and Notch signaling in distal embryonic lung epithelium. (United States)

    El-Hashash, Ahmed H K; Turcatel, Gianluca; Al Alam, Denise; Buckley, Sue; Tokumitsu, Hiroshi; Bellusci, Saverio; Warburton, David


    Cell polarity, mitotic spindle orientation and asymmetric division play a crucial role in the self-renewal/differentiation of epithelial cells, yet little is known about these processes and the molecular programs that control them in embryonic lung distal epithelium. Herein, we provide the first evidence that embryonic lung distal epithelium is polarized with characteristic perpendicular cell divisions. Consistent with these findings, spindle orientation-regulatory proteins Insc, LGN (Gpsm2) and NuMA, and the cell fate determinant Numb are asymmetrically localized in embryonic lung distal epithelium. Interfering with the function of these proteins in vitro randomizes spindle orientation and changes cell fate. We further show that Eya1 protein regulates cell polarity, spindle orientation and the localization of Numb, which inhibits Notch signaling. Hence, Eya1 promotes both perpendicular division as well as Numb asymmetric segregation to one daughter in mitotic distal lung epithelium, probably by controlling aPKCζ phosphorylation. Thus, epithelial cell polarity and mitotic spindle orientation are defective after interfering with Eya1 function in vivo or in vitro. In addition, in Eya1(-/-) lungs, perpendicular division is not maintained and Numb is segregated to both daughter cells in mitotic epithelial cells, leading to inactivation of Notch signaling. As Notch signaling promotes progenitor cell identity at the expense of differentiated cell phenotypes, we test whether genetic activation of Notch could rescue the Eya1(-/-) lung phenotype, which is characterized by loss of epithelial progenitors, increased epithelial differentiation but reduced branching. Indeed, genetic activation of Notch partially rescues Eya1(-/-) lung epithelial defects. These findings uncover novel functions for Eya1 as a crucial regulator of the complex behavior of distal embryonic lung epithelium.

  6. Translocation of Ricin Across Polarized Human Bronchial Epithelial Cells (United States)


    Elsevier Ltd.1. Introduction Native to tropical east Africa, castor bean plants ( Ricinus communis ) are commercially cultivated in many areas of the...junctions permitted toxin to move around the cells, thus gaining entry by paracellular diffusion. 2. Materials and methods 2.1. Materials Ricinus communis ...x: þ1 301 610 2348. .L. Hale). er Ltd.Ricinus communis agglutinin II (ricin) belongs to the type 2 ribosome-inactivating protein family consisting of

  7. Polarity establishment, morphogenesis, and cultured plant cells in space (United States)

    Krikorian, Abraham D.


    Plant development entails an orderly progression of cellular events both in terms of time and geometry. There is only circumstantial evidence that, in the controlled environment of the higher plant embryo sac, gravity may play a role in embryo development. It is still not known whether or not normal embryo development and differentiation in higher plants can be expected to take place reliably and efficiently in the micro g space environment. It seems essential that more attention be given to studying aspects of reproductive biology in order to be confident that plants will survive seed to seed to seed in a space environment. Until the time arrives when successive generations of plants can be grown, the best that can be done is utilize the most appropriate systems and begin, piece meal, to accumulate information on important aspects of plant reproduction. Cultured plant cells can play an important role in these activities since they can be grown so as to be morphogenetically competent, and thus can simulate those embryogenic events more usually identified with fertilized eggs in the embryo sac of the ovule in the ovary. Also, they can be manipulated with relative ease. The extreme plasticity of such demonstrably totipotent cell systems provides a means to test environmental effects such as micro g on a potentially free-running entity. The successful manipulation and management of plant cells and propagules in space also has significance for exploitation of biotechnologies in space since such systems, perforce, are an important vehicle whereby many genetic engineering manipulations are achieved.

  8. Planar cell polarity defects and defective Vangl2 trafficking in mutants for the COPII gene Sec24b

    NARCIS (Netherlands)

    Wansleeben, C.; Feitsma, H.; Montcouquiol, M.; Kroon, C.; Cuppen, E.; Meijlink, F.


    Among the cellular properties that are essential for the organization of tissues during animal development, the importance of cell polarity in the plane of epithelial sheets has become increasingly clear in the past decades. Planar cell polarity (PCP) signaling in vertebrates has indispensable roles

  9. Basolateral invasion and trafficking of Campylobacter jejuni in polarized epithelial cells.

    Directory of Open Access Journals (Sweden)

    Lieneke I Bouwman

    Full Text Available Campylobacter jejuni is a major cause of bacterial diarrheal disease. Most enteropathogenic bacteria including C. jejuni can invade cultured eukaryotic cells via an actin- and/or microtubule-dependent and an energy-consuming uptake process. Recently, we identified a novel highly efficient C. jejuni invasion pathway that involves bacterial migration into the subcellular space of non-polarized epithelial cells (termed subvasion followed by invasion from the cell basis. Here we report cellular requirements of this entry mechanism and the subsequent intracellular trafficking route of C. jejuni in polarized islands of Caco-2 intestinal epithelial cells. Advanced microscopy on infected cells revealed that C. jejuni invades the polarized intestinal cells via the subcellular invasion pathway. Remarkably, invasion was not blocked by the inhibitors of microtubule dynamics colchicine or paclitaxel, and was even enhanced after disruption of host cell actin filaments by cytochalasin D. Invasion also continued after dinitrophenol-induced cellular depletion of ATP, whereas this compound effectively inhibited the uptake of invasive Escherichia coli. Confocal microscopy demonstrated that intracellular C. jejuni resided in membrane-bound CD63-positive cellular compartments for up to 24 h. Establishment of a novel luciferase reporter-based bacterial viability assay, developed to overcome the limitations of the classical bacterial recovery assay, demonstrated that a subset of C. jejuni survived intracellularly for up to 48 h. Taken together, our results indicate that C. jejuni is able to actively invade polarized intestinal epithelial cells via a novel actin- and microtubule-independent mechanism and remains metabolically active in the intracellular niche for up to 48 hours.

  10. Hybrid T-helper cells: stabilizing the moderate center in a polarized system.

    Directory of Open Access Journals (Sweden)

    Sui Huang

    Full Text Available Polarization of cell phenotypes, a common strategy to achieve cell type diversity in metazoa, results from binary cell-fate decisions in the branching pedigree of development. Such "either-or" fate decisions are controlled by two opposing cell fate-determining transcription factors. Each of the two distinct "master regulators" promotes differentiation of its respective sister lineage. But they also suppress one other, leading to their mutually exclusive expression in the two ensuing lineages. Thus, promiscuous coexistence of the antagonist regulators in the same cell, the hallmark of the common "undecided" progenitor of two sister lineages, is considered unstable. This antagonism ensures robust polarization into two discretely distinct cell types. But now the immune system's T-helper (Th cells and their two canonical subtypes, Th1 and Th2 cells, tell a different story, as revealed in three papers recently published in PLOS Biology. The intermediate state that co-expresses the two opposing master regulators of the Th1 and Th2 subtypes, T-bet and Gata3, is highly stable and is not necessarily an undecided precursor. Instead, the Th1/Th2 hybrid cell is a robust new type with properties of both Th1 and Th2 cells. These hybrid cells are functionally active and possess the benefit of moderation: self-limitation of effector T cell function to prevent excessive inflammation, a permanent risk in host defense that can cause tissue damage or autoimmunity. Gene regulatory network analysis suggests that stabilization of the intermediate center in a polarizing system can be achieved by minor tweaking of the architecture of the mutual suppression gene circuit, and thus is a design option readily available to evolution.

  11. MiR-16 regulates mouse peritoneal macrophage polarization and affects T-cell activation. (United States)

    Jia, Xiaoqin; Li, Xiaomin; Shen, Yating; Miao, Junjun; Liu, Hao; Li, Guoli; Wang, Zhengbing


    MiR-16 is a tumour suppressor that is down-regulated in certain human cancers. However, little is known on its activity in other cell types. In this study, we examined the biological significance and underlying mechanisms of miR-16 on macrophage polarization and subsequent T-cell activation. Mouse peritoneal macrophages were isolated and induced to undergo either M1 polarization with 100 ng/ml of interferon-γ and 20 ng/ml of lipopolysaccharide, or M2 polarization with 20 ng/ml of interleukin (IL)-4. The identity of polarized macrophages was determined by profiling cell-surface markers by flow cytometry and cytokine production by ELISA. Macrophages were infected with lentivirus-expressing miR-16 to assess the effects of miR-16. Effects on macrophage-T cell interactions were analysed by co-culturing purified CD4(+) T cells with miR-16-expressing peritoneal macrophages, and measuring activation marker CD69 by flow cytometry and cytokine secretion by ELISA. Bioinformatics analysis was applied to search for potential miR-16 targets and understand its underlying mechanisms. MiR-16-induced M1 differentiation of mouse peritoneal macrophages from either the basal M0- or M2-polarized state is indicated by the significant up-regulation of M1 marker CD16/32, repression of M2 marker CD206 and Dectin-1, and increased secretion of M1 cytokine IL-12 and nitric oxide. Consistently, miR-16-expressing macrophages stimulate the activation of purified CD4(+) T cells. Mechanistically, miR-16 significantly down-regulates the expression of PD-L1, a critical immune suppressor that controls macrophage-T cell interaction and T-cell activation. MiR-16 plays an important role in shifting macrophage polarization from M2 to M1 status, and functionally activating CD4(+) T cells. This effect is potentially mediated through the down-regulation of immune suppressor PD-L1.

  12. Influenza H5N1 virus infection of polarized human alveolar epithelial cells and lung microvascular endothelial cells

    Directory of Open Access Journals (Sweden)

    Yuen Kit M


    Full Text Available Abstract Background Highly pathogenic avian influenza (HPAI H5N1 virus is entrenched in poultry in Asia and Africa and continues to infect humans zoonotically causing acute respiratory disease syndrome and death. There is evidence that the virus may sometimes spread beyond respiratory tract to cause disseminated infection. The primary target cell for HPAI H5N1 virus in human lung is the alveolar epithelial cell. Alveolar epithelium and its adjacent lung microvascular endothelium form host barriers to the initiation of infection and dissemination of influenza H5N1 infection in humans. These are polarized cells and the polarity of influenza virus entry and egress as well as the secretion of cytokines and chemokines from the virus infected cells are likely to be central to the pathogenesis of human H5N1 disease. Aim To study influenza A (H5N1 virus replication and host innate immune responses in polarized primary human alveolar epithelial cells and lung microvascular endothelial cells and its relevance to the pathogenesis of human H5N1 disease. Methods We use an in vitro model of polarized primary human alveolar epithelial cells and lung microvascular endothelial cells grown in transwell culture inserts to compare infection with influenza A subtype H1N1 and H5N1 viruses via the apical or basolateral surfaces. Results We demonstrate that both influenza H1N1 and H5N1 viruses efficiently infect alveolar epithelial cells from both apical and basolateral surface of the epithelium but release of newly formed virus is mainly from the apical side of the epithelium. In contrast, influenza H5N1 virus, but not H1N1 virus, efficiently infected polarized microvascular endothelial cells from both apical and basolateral aspects. This provides a mechanistic explanation for how H5N1 virus may infect the lung from systemic circulation. Epidemiological evidence has implicated ingestion of virus-contaminated foods as the source of infection in some instances and our

  13. Competition for actin between two distinct F-actin networks defines a bistable switch for cell polarization. (United States)

    Lomakin, Alexis J; Lee, Kun-Chun; Han, Sangyoon J; Bui, Duyen A; Davidson, Michael; Mogilner, Alex; Danuser, Gaudenz


    Symmetry-breaking polarization enables functional plasticity of cells and tissues and is yet not well understood. Here we show that epithelial cells, hard-wired to maintain a static morphology and to preserve tissue organization, can spontaneously switch to a migratory polarized phenotype after relaxation of the actomyosin cytoskeleton. We find that myosin II engages actin in the formation of cortical actomyosin bundles and thus makes it unavailable for deployment in the process of dendritic growth normally driving cell motility. Under low-contractility regimes, epithelial cells polarize in a front-back manner owing to the emergence of actin retrograde flows powered by dendritic polymerization of actin. Coupled to cell movement, the flows transport myosin II from the front to the back of the cell, where the motor locally 'locks' actin in contractile bundles. This polarization mechanism could be employed by embryonic and cancer epithelial cells in microenvironments where high-contractility-driven cell motion is inefficient.

  14. Second generation hybrid polar compounds are potent inducers of transformed cell differentiation. (United States)

    Richon, V M; Webb, Y; Merger, R; Sheppard, T; Jursic, B; Ngo, L; Civoli, F; Breslow, R; Rifkind, R A; Marks, P A


    Hybrid polar compounds, of which hexamethylenebisacetamide (HMBA) is the prototype, are potent inducers of differentiation of murine erythroleukemia (MEL) cells and a wide variety of other transformed cells. HMBA has been shown to induce differentiation of neoplastic cells in patients, but is not an adequate therapeutic agent because of dose-limiting toxicity. We report on a group of three potent second generation hybrid polar compounds, diethyl bis-(pentamethylene-N,N-dimethylcarboxamide) malonate (EMBA), suberoylanilide hydroxamic acid (SAHA), and m-carboxycinnamic acid bis-hydroxamide (CBHA) with optimal concentrations for inducing MEL cells of 0.4 mM, 2 microM, and 4 microM, respectively, compared to 5 mM for HMBA. All three agents induce accumulation of underphosphorylated pRB; increased levels of p2l protein, a prolongation of the initial G1 phase of the cell cycle; and accumulation of hemoglobin. However, based upon their effective concentrations, the cross-resistance or sensitivity of an HMBA-resistant MEL cell variant, and differences in c-myb expression during induction, these differentiation-inducing hybrid polar compounds can be grouped into two subsets, HMBA/EMBA and SAHA/CBHA. This classification may prove of value in selecting and planning prospective preclinical and clinical studies toward the treatment of cancer by differentiation therapy.

  15. The influence of artificial-thunderstorm cell polarity on discharge initiation by model hydrometeor arrays (United States)

    Temnikov, A. G.; Chernenskii, L. L.; Orlov, A. V.; Lysov, N. Yu.; Belova, O. S.; Kalugina, I. E.; Gerastenok, T. K.; Zhuravkova, D. S.


    The initiation of discharge by model hydrometeors between an artificial-thunderstorm cell (aerosol cloud) of negative or positive polarity and ground has been experimentally studied. It is established for the first time that the conditions of cloud-ground spark discharge initiation by hydrometeors, as well as the characteristics of discharge significantly depend on the polarity of charged cloud. The effect of hydrometeor arrays can be manifested by the cloud-ground lightning initiated in a thundercloud and used for developing scientific principles of artificial lightning discharge.

  16. Synthetic interaction between the TipN polarity factor and an AcrAB-family efflux pump implicates cell polarity in bacterial drug resistance. (United States)

    Kirkpatrick, Clare L; Viollier, Patrick H


    Quinolone antibiotics are clinically important drugs that target bacterial DNA replication and chromosome segregation. Although the AcrAB-family efflux pumps generally protect bacteria from such drugs, the physiological role of these efflux systems and their interplay with other cellular events are poorly explored. Here, we report an intricate relationship between antibiotic resistance and cell polarity in the model bacterium Caulobacter crescentus. We show that a polarity landmark protein, TipN, identified by virtue of its ability to direct flagellum placement to the new cell pole, protects cells from toxic misregulation of an AcrAB efflux pump through a cis-encoded nalidixic acid-responsive transcriptional repressor. Alongside the importance of polarity in promoting the inheritance and activity of virulence functions including motility, we can now ascribe to it an additional role in drug resistance that is distinct from classical efflux mechanisms.

  17. LARG and mDia1 link Galpha12/13 to cell polarity and microtubule dynamics. (United States)

    Goulimari, Polyxeni; Knieling, Helga; Engel, Ulrike; Grosse, Robert


    Regulation of cell polarity is a process observed in all cells. During directed migration, cells orientate their microtubule cytoskeleton and the microtubule-organizing-center (MTOC), which involves integrins and downstream Cdc42 and glycogen synthase kinase-3beta activity. However, the contribution of G protein-coupled receptor signal transduction for MTOC polarity is less well understood. Here, we report that the heterotrimeric Galpha(12) and Galpha(13) proteins are necessary for MTOC polarity and microtubule dynamics based on studies using Galpha(12/13)-deficient mouse embryonic fibroblasts. Cell polarization involves the Galpha(12/13)-interacting leukemia-associated RhoGEF (LARG) and the actin-nucleating diaphanous formin mDia1. Interestingly, LARG associates with pericentrin and localizes to the MTOC and along microtubule tracks. We propose that Galpha(12/13) proteins exert essential functions linking extracellular signals to microtubule dynamics and cell polarity via RhoGEF and formin activity.

  18. The role of G protein-coupled receptors in cochlear planar cell polarity. (United States)

    Sun, Jinpeng; Zhang, Daolai; Wang, Yanfei; Lin, Hal; Yu, Xiao; Xu, Zhigang


    Planar cell polarity (PCP) is defined as the coordinated alignment of cell polarity across the tissue plane, which is important for the integration of cells into tissues. One of the best examples of PCP is in the cochlear epithelium. Several core PCP proteins have been identified to play important roles in PCP regulation, in which these proteins form complexes and associate with the cell membrane asymmetrically, mediating intercellular PCP signal transduction. Among the core PCP proteins are two G protein-coupled receptors (GPCRs), Celsr and Frizzled, both of which have been shown to play important roles in cochlear PCP regulation. Celsr and Frizzled genes are expressed in the cochlear sensory epithelium, and Frizzled1, 2, 3 and 6 show asymmetric localizations on the cell membrane of hair cells or supporting cells. In the animal model, Celsr1, Frizzled2 and Frizzled3/6 mutant or knockout mice have profound cochlear PCP deficits. Downstream of GPCR signaling, Gαi was shown to asymmetrically localize on the apical surface of hair cells, together with LGN and mInsc, Gαi controls cochlear PCP in a cell-autonomous way. Inactivity of Gαi, LGN or mInsc results in PCP deficits in the mouse cochlea. We hypothesize that GPCR-Gαi coupling plays a pivotal role in cochlear PCP regulation via connecting the intercellular PCP signals with cell-autonomous PCP machinery. Further investigations are needed to fully understand the mechanism of cochlear PCP regulation.

  19. Is a persistent global bias necessary for the establishment of planar cell polarity?

    Directory of Open Access Journals (Sweden)

    Sabine Fischer

    Full Text Available Planar cell polarity (PCP--the coordinated polarisation of a whole field of cells within the plane of a tissue-relies on the interaction of three modules: a global module that couples individual cellular polarity to the tissue axis, a local module that aligns the axis of polarisation of neighbouring cells, and a readout module that directs the correct outgrowth of PCP-regulated structures such as hairs and bristles. While much is known about the molecular components that are required for PCP, the functional details of--and interactions between--the modules remain unclear. In this work, we perform a mathematical and computational analysis of two previously proposed computational models of the local module (Amonlirdviman et al., Science, 307, 2005; Le Garrec et al., Dev. Dyn., 235, 2006. Both models can reproduce wild-type and mutant phenotypes of PCP observed in the Drosophila wing under the assumption that a tissue-wide polarity cue from the global module persists throughout the development of PCP. We demonstrate that both models can also generate tissue-level PCP when provided with only a transient initial polarity cue. However, in these models such transient cues are not sufficient to ensure robustness of the resulting cellular polarisation.

  20. Shear stress regulates forward and reverse planar cell polarity of vascular endothelium in vivo and in vitro. (United States)

    McCue, Shannon; Dajnowiec, Dorota; Xu, Feng; Zhang, Ming; Jackson, Moira R; Langille, B Lowell


    Cultured vascular endothelium displays profound morphological adaptations to shear stress that include planar cell polarity (PCP) that is directed downstream. Endothelial cells in blood vessels are also polarized; however, the direction of polarity is vessel specific, and shear-independent mechanisms have been inferred. The regulation of endothelial PCP is therefore controversial. We report that the direction of PCP in blood vessels is age and vessel specific; nonetheless, it is caused by shear-related regulation of glycogen synthase kinase-3beta (GSK-3beta), a profound regulator of endothelial microtubule stability. When GSK-3beta is inhibited, PCP reverses direction. Endothelium is the only cell type studied to date that can reverse direction of polarity. Tight regulation of GSK-3beta, microtubule dynamics, and cell polarity was also required for the striking morphological responses of endothelium to shear stress (cell elongation and orientation with shear). Finally, the cytoskeletal polarity displayed in blood vessels is associated with polarized (shear-directed) cell mitoses that have important effects on endothelial repair. Vascular endothelium therefore displays a novel mode of mechanosensitive PCP that represents the first example of a single cell type that can reverse direction of polarity.

  1. Planar cell polarity genes, Celsr1-3, in neural development

    Institute of Scientific and Technical Information of China (English)

    Jia Feng; Qi Han; Libing Zhou


    flamingo is among the ‘core' planar cell-polarity genes,protein of which belongs to a unique cadherin subfamily.In contrast to the classic cadherins,composed of several cxtracellular cadhcrin repcats,one transmembrane domain and one cytoplasmic segment linked to catenin binding,Drosophila Flamingo has seven transmembrane segments and a cytoplasmic tail with no catenin-binding sequence.In Drosophila,Flamingo has pleotropic roles in controlling epithelial polarity and neuronal morphogenesis.Three mammalian orthologs of flamingo,Celsr1-3,are widely expressed in the nervous system.Recent work has shown that Celsr1-3 play important roles in neural development,such as in axon guidance,neuronal migration,and cilium polarity.Celsr1-3 single-gene knockout mice exhibit different phenotypes,but there are cooperative interactions among these genes.

  2. Cell polarity and patterning by PIN trafficking through early endosomal compartments in Arabidopsis thaliana.

    Directory of Open Access Journals (Sweden)

    Hirokazu Tanaka


    Full Text Available PIN-FORMED (PIN proteins localize asymmetrically at the plasma membrane and mediate intercellular polar transport of the plant hormone auxin that is crucial for a multitude of developmental processes in plants. PIN localization is under extensive control by environmental or developmental cues, but mechanisms regulating PIN localization are not fully understood. Here we show that early endosomal components ARF GEF BEN1 and newly identified Sec1/Munc18 family protein BEN2 are involved in distinct steps of early endosomal trafficking. BEN1 and BEN2 are collectively required for polar PIN localization, for their dynamic repolarization, and consequently for auxin activity gradient formation and auxin-related developmental processes including embryonic patterning, organogenesis, and vasculature venation patterning. These results show that early endosomal trafficking is crucial for cell polarity and auxin-dependent regulation of plant architecture.

  3. Planar cell polarity genes, Celsr1-3, in neural development. (United States)

    Feng, Jia; Han, Qi; Zhou, Libing


    flamingo is among the 'core' planar cell-polarity genes, protein of which belongs to a unique cadherin subfamily. In contrast to the classic cadherins, composed of several extracellular cadherin repeats, one transmembrane domain and one cytoplasmic segment linked to catenin binding, Drosophila Flamingo has seven transmembrane segments and a cytoplasmic tail with no catenin-binding sequence. In Drosophila, Flamingo has pleotropic roles in controlling epithelial polarity and neuronal morphogenesis. Three mammalian orthologs of flamingo, Celsr1-3, are widely expressed in the nervous system. Recent work has shown that Celsr1-3 play important roles in neural development, such as in axon guidance, neuronal migration, and cilium polarity. Celsr1-3 single-gene knockout mice exhibit different phenotypes, but there are cooperative interactions among these genes.

  4. Participation of the cell polarity protein PALS1 to T-cell receptor-mediated NF-κB activation.

    Directory of Open Access Journals (Sweden)

    Gabrielle Carvalho

    Full Text Available BACKGROUND: Beside their established function in shaping cell architecture, some cell polarity proteins were proposed to participate to lymphocyte migration, homing, scanning, as well as activation following antigen receptor stimulation. Although PALS1 is a central component of the cell polarity network, its expression and function in lymphocytes remains unknown. Here we investigated whether PALS1 is present in T cells and whether it contributes to T Cell-Receptor (TCR-mediated activation. METHODOLOGY/PRINCIPAL FINDINGS: By combining RT-PCR and immunoblot assays, we found that PALS1 is constitutively expressed in human T lymphocytes as well as in Jurkat T cells. siRNA-based knockdown of PALS1 hampered TCR-induced activation and optimal proliferation of lymphocyte. We further provide evidence that PALS1 depletion selectively hindered TCR-driven activation of the transcription factor NF-κB. CONCLUSIONS: The cell polarity protein PALS1 is expressed in T lymphocytes and participates to the optimal activation of NF-κB following TCR stimulation.

  5. Polarization of migrating monocytic cells is independent of PI 3-kinase activity.

    Directory of Open Access Journals (Sweden)

    Silvia Volpe

    Full Text Available BACKGROUND: Migration of mammalian cells is a complex cell type and environment specific process. Migrating hematopoietic cells assume a rapid amoeboid like movement when exposed to gradients of chemoattractants. The underlying signaling mechanisms remain controversial with respect to localization and distribution of chemotactic receptors within the plasma membrane and the role of PI 3-kinase activity in cell polarization. METHODOLOGY/PRINCIPAL FINDINGS: We present a novel model for the investigation of human leukocyte migration. Monocytic THP-1 cells transfected with the alpha(2A-adrenoceptor (alpha(2AAR display comparable signal transduction responses, such as calcium mobilization, MAP-kinase activation and chemotaxis, to the noradrenaline homologue UK 14'304 as when stimulated with CCL2, which binds to the endogenous chemokine receptor CCR2. Time-lapse video microscopy reveals that chemotactic receptors remain evenly distributed over the plasma membrane and that their internalization is not required for migration. Measurements of intramolecular fluorescence resonance energy transfer (FRET of alpha(2AAR-YFP/CFP suggest a uniform activation of the receptors over the entire plasma membrane. Nevertheless, PI 3-kinase activation is confined to the leading edge. When reverting the gradient of chemoattractant by moving the dispensing micropipette, polarized monocytes--in contrast to neutrophils--rapidly flip their polarization axis by developing a new leading edge at the previous posterior side. Flipping of the polarization axis is accompanied by re-localization of PI-3-kinase activity to the new leading edge. However, reversal of the polarization axis occurs in the absence of PI 3-kinase activation. CONCLUSIONS/SIGNIFICANCE: Accumulation and internalization of chemotactic receptors at the leading edge is dispensable for cell migration. Furthermore, uniformly distributed receptors allow the cells to rapidly reorient and adapt to changes in the

  6. Trafficking through COPII stabilises cell polarity and drives secretion during Drosophila epidermal differentiation.

    Directory of Open Access Journals (Sweden)

    Michaela Norum

    Full Text Available BACKGROUND: The differentiation of an extracellular matrix (ECM at the apical side of epithelial cells implies massive polarised secretion and membrane trafficking. An epithelial cell is hence engaged in coordinating secretion and cell polarity for a correct and efficient ECM formation. PRINCIPAL FINDINGS: We are studying the molecular mechanisms that Drosophila tracheal and epidermal cells deploy to form their specific apical ECM during differentiation. In this work we demonstrate that the two genetically identified factors haunted and ghost are essential for polarity maintenance, membrane topology as well as for secretion of the tracheal luminal matrix and the cuticle. We show that they code for the Drosophila COPII vesicle-coating components Sec23 and Sec24, respectively, that organise vesicle transport from the ER to the Golgi apparatus. CONCLUSION: Taken together, epithelial differentiation during Drosophila embryogenesis is a concerted action of ECM formation, plasma membrane remodelling and maintenance of cell polarity that all three rely mainly, if not absolutely, on the canonical secretory pathway from the ER over the Golgi apparatus to the plasma membrane. Our results indicate that COPII vesicles constitute a central hub for these processes.

  7. Drosophila Stardust is a partner of Crumbs in the control of epithelial cell polarity. (United States)

    Bachmann, A; Schneider, M; Theilenberg, E; Grawe, F; Knust, E


    The polarized architecture of epithelial cells depends on the highly stereotypic distribution of cellular junctions and other membrane-associated protein complexes. In epithelial cells of the Drosophila embryo, three distinct domains subdivide the lateral plasma membrane. The most apical one comprises the subapical complex (SAC). It is followed by the zonula adherens (ZA) and, further basally, by the septate junction. A core component of the SAC is the transmembrane protein Crumbs, the cytoplasmic domain of which recruits the PDZ-protein Discs Lost into the complex. Cells lacking crumbs or the functionally related gene stardust fail to organize a continuous ZA and to maintain cell polarity. Here we show that stardust provides an essential component of the SAC. Stardust proteins colocalize with Crumbs and bind to the carboxy-terminal amino acids of its cytoplasmic tail. We introduce two different Stardust proteins here: one MAGUK protein, characterized by a PDZ domain, an SH3 domain and a guanylate kinase domain; and a second isoform comprising only the guanylate kinase domain. The Stardust proteins represent versatile candidates as structural and possibly regulatory constituents of the SAC, a crucial element in the control of epithelial cell polarity.

  8. The planar cell polarity gene strabismus regulates convergence and extension and neural fold closure in Xenopus. (United States)

    Goto, Toshiyasu; Keller, Ray


    We cloned Xenopus Strabismus (Xstbm), a homologue of the Drosophila planar cell or tissue polarity gene. Xstbm encodes four transmembrane domains in its N-terminal half and a PDZ-binding motif in its C-terminal region, a structure similar to Drosophila and mouse homologues. Xstbm is expressed strongly in the deep cells of the anterior neural plate and at lower levels in the posterior notochordal and neural regions during convergent extension. Overexpression of Xstbm inhibits convergent extension of mesodermal and neural tissues, as well as neural tube closure, without direct effects on tissue differentiation. Expression of Xstbm(DeltaPDZ-B), which lacks the PDZ-binding region of Xstbm, inhibits convergent extension when expressed alone but rescues the effect of overexpressing Xstbm, suggesting that Xstbm(DeltaPDZ-B) acts as a dominant negative and that both increase and decrease of Xstbm function from an optimum retards convergence and extension. Recordings show that cells expressing Xstbm or Xstbm(DeltaPDZ-B) fail to acquire the polarized protrusive activity underlying normal cell intercalation during convergent extension of both mesodermal and neural and that this effect is population size-dependent. These results further characterize the role of Xstbm in regulating the cell polarity driving convergence and extension in Xenopus.

  9. Polarization Force Microscopy of the Cell-Mineral Interface: Insights Into the Bioelectric Signature (United States)

    Bartosik, E. M.; Kendall, T. A.


    The success of bioremediation strategies is dependent upon effective monitoring of microorganisms in the subsurface. Induced polarization (IP) may represent a cost-effective, complementary technique to existing borehole-based microbe detection schemes. Recent studies show a significant, yet poorly understood IP effect associated with the presence of bacteria in aqueous and porous media. This effect is believed to be rooted in the physicochemical surface interactions between cells and minerals which we probe using polarization and electric force microscopy. Dispersions of the local permittivity inferred from polarization force data that was collected over a hydrated mineral surface correspond to dispersions modeled for a bacterium. In each case, absolute permittivities and frequency cut-off values increase with surface potential and ion mobility, respectively. Potentially similar polarization mechanisms between the inorganic and organic condition are inferred. Further polarization force microscopy measurements of the mineral-microbe interface will provide molecular-level insight that complements column and field-scale IP observations. Anticipated is a more comprehensive mechanisitic description of the bioelectric IP response that facilitates application of IP to bioremediation.

  10. Restoration of cell polarity and bile excretion function of hepatocytes in sandwich-culture

    Institute of Scientific and Technical Information of China (English)

    ZHANG Xian-jie; WANG Ying; SUN Jia-bang; SONG Mao-min; QIAO Xin


    Objective:To investigate the nature of the restoration of cell polarity and bile excretion function in Sandwich-cultured hepatocytes.Methods:Freshly isolated hepatocytes from male Sprague-Dawley rats were cultured in a double layer collagen gel Sandwich configuration.Morphological changes were observed under a inverted microscope.The domain specific membrane associated protein DPP Ⅳ was tested by immunofluorescenee,and the bile excretion function was determined by using fluorescein diacetate.Hepatocytes cultured on a single layer of collagen gel were taken as control.Results:Adult rat hepatocytes cultured in a double layer collagen gel sandwich configuration regained its morphological and functional polarity and maintained polygonal morphology for at least 4 weeks.Immunofluorescence studies USing antibodies against DPP Ⅳ showed polarity restoration as early as 48 h.After cultured in the double layer collagen gel Sandwich configuration for 96 h the hepatocytes began to excrete bile;while hepatocytes cultured on a single layer collagen gel had no bile excretion.Conclusion:Hepatocytes cultured in a double layer collagen gel Sandwich configuration are able to regain their morphological and functional polarity givan certain conditions.Hepaotcyte culture is a useful tool for the study of polarity restoration.

  11. Galileo Station Keeping Strategy (United States)

    Perez-Cambriles, Antonio; Bejar-Romero, Juan Antonio; Aguilar-Taboada, Daniel; Perez-Lopez, Fernando; Navarro, Daniel


    This paper presents analyses done for the design and implementation of the Maneuver Planning software of the Galileo Flight Dynamics Facility. The station keeping requirements of the constellation have been analyzed in order to identify the key parameters to be taken into account in the design and implementation of the software.

  12. Keeping The Faith

    Institute of Scientific and Technical Information of China (English)


    More young people are turning to Buddhism as the ancient philosophy strives to keep up with the times Yin Xiaotian, 37, is successful, modern and ambitious. In his car, a blessing card hangs from the rearview mirror. On one side of the card is a picture of Mao Zedong.

  13. Record Keeping Guidelines (United States)

    American Psychologist, 2007


    These guidelines are designed to educate psychologists and provide a framework for making decisions regarding professional record keeping. State and federal laws, as well as the American Psychological Association's "Ethical Principles of Psychologists and Code of Conduct," generally require maintenance of appropriate records of psychological…

  14. Keeping Food Safe

    Centers for Disease Control (CDC) Podcasts


    This CDC Kidtastics podcast discusses things kids and parents can do to help prevent illness by keeping food safe.  Created: 5/27/2009 by National Center for Zoonotic, Vector-Borne, and Enteric Diseases (NCZVED).   Date Released: 5/27/2009.

  15. The planar cell polarity protein VANGL2 coordinates remodeling of the extracellular matrix. (United States)

    Williams, B Blairanne; Mundell, Nathan; Dunlap, Julie; Jessen, Jason


    Understanding how planar cell polarity (PCP) is established, maintained, and coordinated in migrating cell populations is an important area of research with implications for both embryonic morphogenesis and tumor cell invasion. We recently reported that the PCP protein Vang-like 2 (VANGL2) regulates the endocytosis and cell surface level of membrane type-1 matrix metalloproteinase (MMP14 or MT1-MMP). Here, we further discuss these findings in terms of extracellular matrix (ECM) remodeling, cell migration, and zebrafish gastrulation. We also demonstrate that VANGL2 function impacts the focal degradation of ECM by human cancer cells including the formation or stability of invadopodia. Together, our findings implicate MMP14 as a downstream effector of VANGL2 signaling and suggest a model whereby the regulation of pericellular proteolysis is a fundamental aspect of PCP in migrating cells.

  16. Cdc42 is not essential for filopodium formation, directed migration, cell polarization, and mitosis in fibroblastoid cells

    DEFF Research Database (Denmark)

    Czuchra, Aleksandra; Wu, Xunwei; Meyer, Hannelore


    apparatus into the direction of migration was decreased. However, expression of dominant negative Cdc42 in Cdc42-null cells resulted in strongly reduced directed migration, severely reduced single cell directionality, and complete loss of Golgi polarization and of directionality of protrusion formation...... of Cdc42 did not affect filopodium or lamellipodium formation and had no significant influence on the speed of directed migration nor on mitosis. Cdc42-deficient cells displayed a more elongated cell shape and had a reduced area. Furthermore, directionality during migration and reorientation of the Golgi...

  17. N-cadherin is required for the polarized cell behaviors that drive neurulation in the zebrafish. (United States)

    Hong, Elim; Brewster, Rachel


    Through the direct analysis of cell behaviors, we address the mechanisms underlying anterior neural tube morphogenesis in the zebrafish and the role of the cell adhesion molecule N-cadherin (N-cad) in this process. We demonstrate that although the mode of neurulation differs at the morphological level between amphibians and teleosts, the underlying cellular mechanisms are conserved. Contrary to previous reports, the zebrafish neural plate is a multi-layered structure, composed of deep and superficial cells that converge medially while undergoing radial intercalation, to form a single cell-layered neural tube. Time-lapse recording of individual cell behaviors reveals that cells are polarized along the mediolateral axis and exhibit protrusive activity. In N-cad mutants, both convergence and intercalation are blocked. Moreover, although N-cad-depleted cells are not defective in their ability to form protrusions, they are unable to maintain them stably. Taken together, these studies uncover key cellular mechanisms underlying neural tube morphogenesis in teleosts, and reveal a role for cadherins in promoting the polarized cell behaviors that underlie cellular rearrangements and shape the vertebrate embryo.

  18. Positioning of centrioles is a conserved readout of Frizzled planar cell polarity signalling. (United States)

    Carvajal-Gonzalez, Jose Maria; Roman, Angel-Carlos; Mlodzik, Marek


    Planar cell polarity (PCP) signalling is a well-conserved developmental pathway regulating cellular orientation during development. An evolutionarily conserved pathway readout is not established and, moreover, it is thought that PCP mediated cellular responses are tissue-specific. A key PCP function in vertebrates is to regulate coordinated centriole/cilia positioning, a function that has not been associated with PCP in Drosophila. Here we report instructive input of Frizzled-PCP (Fz/PCP) signalling into polarized centriole positioning in Drosophila wings. We show that centrioles are polarized in pupal wing cells as a readout of PCP signalling, with both gain and loss-of-function Fz/PCP signalling affecting centriole polarization. Importantly, loss or gain of centrioles does not affect Fz/PCP establishment, implicating centriolar positioning as a conserved PCP-readout, likely downstream of PCP-regulated actin polymerization. Together with vertebrate data, these results suggest a unifying model of centriole/cilia positioning as a common downstream effect of PCP signalling from flies to mammals.

  19. Self-Organization of Polarized Cerebellar Tissue in 3D Culture of Human Pluripotent Stem Cells

    Directory of Open Access Journals (Sweden)

    Keiko Muguruma


    Full Text Available During cerebellar development, the main portion of the cerebellar plate neuroepithelium gives birth to Purkinje cells and interneurons, whereas the rhombic lip, the germinal zone at its dorsal edge, generates granule cells and cerebellar nuclei neurons. However, it remains elusive how these components cooperate to form the intricate cerebellar structure. Here, we found that a polarized cerebellar structure self-organizes in 3D human embryonic stem cell (ESC culture. The self-organized neuroepithelium differentiates into electrophysiologically functional Purkinje cells. The addition of fibroblast growth factor 19 (FGF19 promotes spontaneous generation of dorsoventrally polarized neural-tube-like structures at the level of the cerebellum. Furthermore, addition of SDF1 and FGF19 promotes the generation of a continuous cerebellar plate neuroepithelium with rhombic-lip-like structure at one end and a three-layer cytoarchitecture similar to the embryonic cerebellum. Thus, human-ESC-derived cerebellar progenitors exhibit substantial self-organizing potential for generating a polarized structure reminiscent of the early human cerebellum at the first trimester.

  20. The clathrin adaptor AP-1 complex and Arf1 regulate planar cell polarity in vivo. (United States)

    Carvajal-Gonzalez, Jose Maria; Balmer, Sophie; Mendoza, Meg; Dussert, Aurore; Collu, Giovanna; Roman, Angel-Carlos; Weber, Ursula; Ciruna, Brian; Mlodzik, Marek


    A key step in generating planar cell polarity (PCP) is the formation of restricted junctional domains containing Frizzled/Dishevelled/Diego (Fz/Dsh/Dgo) or Van Gogh/Prickle (Vang/Pk) complexes within the same cell, stabilized via Flamingo (Fmi) across cell membranes. Although models have been proposed for how these complexes acquire and maintain their polarized localization, the machinery involved in moving core PCP proteins around cells remains unknown. We describe the AP-1 adaptor complex and Arf1 as major regulators of PCP protein trafficking in vivo. AP-1 and Arf1 disruption affects the accumulation of Fz/Fmi and Vang/Fmi complexes in the proximo-distal axis, producing severe PCP phenotypes. Using novel tools, we demonstrate a direct and specific Arf1 involvement in Fz trafficking in vivo. Moreover, we uncover a conserved Arf1 PCP function in vertebrates. Our data support a model whereby the trafficking machinery plays an important part during PCP establishment, promoting formation of polarized PCP-core complexes in vivo.

  1. Coupling mechanical deformations and planar cell polarity to create regular patterns in the zebrafish retina.

    Directory of Open Access Journals (Sweden)

    Guillaume Salbreux

    Full Text Available The orderly packing and precise arrangement of epithelial cells is essential to the functioning of many tissues, and refinement of this packing during development is a central theme in animal morphogenesis. The mechanisms that determine epithelial cell shape and position, however, remain incompletely understood. Here, we investigate these mechanisms in a striking example of planar order in a vertebrate epithelium: The periodic, almost crystalline distribution of cone photoreceptors in the adult teleost fish retina. Based on observations of the emergence of photoreceptor packing near the retinal margin, we propose a mathematical model in which ordered columns of cells form as a result of coupling between planar cell polarity (PCP and anisotropic tissue-scale mechanical stresses. This model recapitulates many observed features of cone photoreceptor organization during retinal growth and regeneration. Consistent with the model's predictions, we report a planar-polarized distribution of Crumbs2a protein in cone photoreceptors in both unperturbed and regenerated tissue. We further show that the pattern perturbations predicted by the model to occur if the imposed stresses become isotropic closely resemble defects in the cone pattern in zebrafish lrp2 mutants, in which intraocular pressure is increased, resulting in altered mechanical stress and ocular enlargement. Evidence of interactions linking PCP, cell shape, and mechanical stresses has recently emerged in a number of systems, several of which show signs of columnar cell packing akin to that described here. Our results may hence have broader relevance for the organization of cells in epithelia. Whereas earlier models have allowed only for unidirectional influences between PCP and cell mechanics, the simple, phenomenological framework that we introduce here can encompass a broad range of bidirectional feedback interactions among planar polarity, shape, and stresses; our model thus represents a

  2. Prickle mediates feedback amplification to generate asymmetric planar cell polarity signaling. (United States)

    Tree, David R P; Shulman, Joshua M; Rousset, Raphaël; Scott, Matthew P; Gubb, David; Axelrod, Jeffrey D


    Planar cell polarity signaling in Drosophila requires the receptor Frizzled and the cytoplasmic proteins Dishevelled and Prickle. From initial, symmetric subcellular distributions in pupal wing cells, Frizzled and Dishevelled become highly enriched at the distal portion of the cell cortex. We describe a Prickle-dependent intercellular feedback loop that generates asymmetric Frizzled and Dishevelled localization. In the absence of Prickle, Frizzled and Dishevelled remain symmetrically distributed. Prickle localizes to the proximal side of pupal wing cells and binds the Dishevelled DEP domain, inhibiting Dishevelled membrane localization and antagonizing Frizzled accumulation. This activity is linked to Frizzled activity on the adjacent cell surface. Prickle therefore functions in a feedback loop that amplifies differences between Frizzled levels on adjacent cell surfaces.

  3. Study of Collagen Birefringence in Different Grades of Oral Squamous Cell Carcinoma Using Picrosirius Red and Polarized Light Microscopy



    Objectives. The present study was done to evaluate birefringence pattern of collagen fibres in different grades of oral squamous cell carcinoma using Picrosirius red stain and polarization microscopy and to determine if there is a change in collagen fibres between different grades of oral squamous cell carcinoma. Materials and Methods. Picrosirius red stained 5 μm thick sections of previously diagnosed different grades of squamous cell carcinoma and normal oral mucosa were studied under polar...

  4. The role of VAMP7/TI-VAMP in cell polarity and lysosomal exocytosis in vivo. (United States)

    Sato, Mahito; Yoshimura, Shinichiro; Hirai, Rika; Goto, Ayako; Kunii, Masataka; Atik, Nur; Sato, Takashi; Sato, Ken; Harada, Reiko; Shimada, Junko; Hatabu, Toshimitsu; Yorifuji, Hiroshi; Harada, Akihiro


    VAMP7 or tetanus neurotoxin-insensitive vesicle- associated membrane protein (TI-VAMP) has been proposed to regulate apical transport in polarized epithelial cells, axonal transport in neurons and lysosomal exocytosis. To investigate the function of VAMP7 in vivo, we generated VAMP7 knockout mice. Here, we show that VAMP7 knockout mice are indistinguishable from control mice and display a similar localization of apical proteins in the kidney and small intestine and a similar localization of axonal proteins in the nervous system. Neurite outgrowth of cultured mutant hippocampal neurons was reduced in mutant neurons. However, lysosomal exocytosis was not affected in mutant fibroblasts. Our results show that VAMP7 is required in neurons to extend axons to the full extent. However, VAMP7 does not seem to be required for epithelial cell polarity and lysosomal exocytosis.

  5. Cdc42 regulates epithelial cell polarity and cytoskeletal function during kidney tubule development

    DEFF Research Database (Denmark)

    Elias, Bertha C; Das, Amrita; Parekh, Diptiben V


    The Rho GTPase Cdc42 regulates key signaling pathways required for multiple cell functions, including maintenance of shape, polarity, proliferation, migration, differentiation and morphogenesis. Although previous studies have shown that Cdc42 is required for proper epithelial development and main......The Rho GTPase Cdc42 regulates key signaling pathways required for multiple cell functions, including maintenance of shape, polarity, proliferation, migration, differentiation and morphogenesis. Although previous studies have shown that Cdc42 is required for proper epithelial development...... and maintenance, its exact molecular function in kidney development is not well understood. In this study, we define the specific role of Cdc42 during murine kidney epithelial tubulogenesis by deleting it selectively at the initiation of ureteric bud or metanephric mesenchyme development. Deletion in either...

  6. Kv7.1 surface expression is regulated by epithelial cell polarization

    DEFF Research Database (Denmark)

    Andersen, Martin N; Olesen, Søren-Peter; Rasmussen, Hanne Borger


    The potassium channel K(V)7.1 is expressed in the heart where it contributes to the repolarization of the cardiac action potential. In addition, K(V)7.1 is expressed in epithelial tissues where it plays a role in salt and water transport. Mutations in the kcnq1 gene can lead to long QT syndrome...... and deafness, and several mutations have been described as trafficking mutations. To learn more about the basic mechanisms that regulate K(V)7.1 surface expression, we have investigated the trafficking of K(V)7.1 during the polarization process of the epithelial cell line Madin-Darby Canine Kidney (MDCK) using...... is regulated by signaling mechanisms involved in epithelial cell polarization in particular signaling cascades involving protein kinase C and PI3K....

  7. Interaction of red blood cells with a polarized electrode: evidence of long-range intermolecular forces. (United States)

    Gingell, D; Fornes, J A


    We have investigated the electrostatic interaction of glutaraldehyde-fixed human red cells with a polarizable electrode carrying a defined surface charge density which can be varied continuously through a wide range. Cells in a dilute salt solution are unable to adhere to the electrode at high negative charge, but at lower negative charge densities they are reversibly adherent and can be forced off by increasing the negative polarization. Near zero electrode charge they become irreversibly stuck to the electrode and cannot be evicted even at maximum electrode polarization. Calculation of the electrostatic repulsive force using measured charge densities indicates the existence of an attractive force which may be acting over several hundred angstroms.

  8. Telling stories: keeping secrets. (United States)

    Jensen, Joan M


    This article addresses the reticence of some farm women to share their experiences with historians and how that desire to keep secrets collides with the desire by scholars to tell the stories of these women. It argues that scholars must continue to struggle with the issue of which stories to tell publicly and which to keep private. The author discusses her own experience telling stories about rural women in the 1970s and the need to give voice to the heritage of rural women, especially of groups that have feared revealing their experiences. She offers examples of historians of rural women who have successfully worked with formerly silenced populations and urges historians to continue to tell stories about these lives, to reevaluate what has been already learned, to ask new questions, and to discuss which secrets need to be shared.

  9. Ciliary proteins Bbs8 and Ift20 promote planar cell polarity in the cochlea. (United States)

    May-Simera, Helen L; Petralia, Ronald S; Montcouquiol, Mireille; Wang, Ya-Xian; Szarama, Katherine B; Liu, Yun; Lin, Weichun; Deans, Michael R; Pazour, Gregory J; Kelley, Matthew W


    Primary cilia have been implicated in the generation of planar cell polarity (PCP). However, variations in the severity of polarity defects in different cilia mutants, coupled with recent demonstrations of non-cilia-related actions of some cilia genes, make it difficult to determine the basis of these polarity defects. To address this issue, we evaluated PCP defects in cochlea from a selection of mice with mutations in cilia-related genes. Results indicated notable PCP defects, including mis-oriented hair cell stereociliary bundles, in Bbs8 and Ift20 single mutants that are more severe than in other cilia gene knockouts. In addition, deletion of either Bbs8 or Ift20 results in disruptions in asymmetric accumulation of the core PCP molecule Vangl2 in cochlear cells, suggesting a role for Bbs8 and/or Ift20, possibly upstream of core PCP asymmetry. Consistent with this, co-immunoprecipitation experiments indicate direct interactions of Bbs8 and Ift20 with Vangl2. We observed localization of Bbs and Ift proteins to filamentous actin as well as microtubules. This could implicate these molecules in selective trafficking of membrane proteins upstream of cytoskeletal reorganization, and identifies new roles for cilia-related proteins in cochlear PCP.

  10. Glycoproteins from sugarcane plants regulate cell polarity of Ustilago scitaminea teliospores. (United States)

    Millanes, Ana-María; Fontaniella, Blanca; Legaz, María-Estrella; Vicente, Carlos


    Saccharum officinarum, cv. Mayarí, is a variety of sugarcane resistant to smut disease caused by Ustilago scitaminea. Sugarcane naturally produces glycoproteins that accumulate in the parenchymatous cells of stalks. These glycoproteins contain a heterofructan as polysaccharide moiety. The concentration of these glycoproteins clearly increases after inoculation of sugarcane plants with smut teliospores, although major symptoms of disease are not observed. These glycoproteins induce homotypic adhesion and inhibit teliospore germination. When glycoproteins from healthy, non-inoculated plants are fractionated, they inhibit actin capping, which occurs before teliospore germination. However, inoculation of smut teliospores induce glycoprotein fractions that promote teliospore polarity and are different from those obtained from healthy plants. These fractions exhibit arginase activity, which is strongly enhanced in inoculated plants. Arginase from healthy plants binds to cell wall teliospores and it is completely desorpted by sucrose, but only 50% of arginase activity from inoculated plants is desorpted by the disaccharide. The data presented herein are consistent with a model of excess arginase entry into teliospores. Arginase synthesized by sugarcane plants as a response to the experimental infection would increase the synthesis of putrescine, which impedes polarization at concentration values higher than 0.05 mM. However, smut teliospores seem to be able to change the pattern of glycoprotein production by sugarcane, thereby promoting the synthesis of different glycoproteins that activate polarization after binding to their cell wall ligand.

  11. Circularly Polarized Transparent Microstrip Patch Reflectarray Integrated with Solar Cell for Satellite Applications

    Directory of Open Access Journals (Sweden)

    S. H. Zainud-Deen


    Full Text Available Circularly polarized (CP transparent microstrip reflectarray antenna is integrated with solar cell for small satellite applications at 10 GHz. The reflectarray unit cell consists of a perfect electric conductor (PEC square patch printed on an optically transparent substrate with the PEC ground plane. A comparison between using transparent conducting polymers and using the PEC in unit-cell construction has been introduced. The waveguide simulator is used to calculate the required compensation phase of each unit cell in the reflectarray. The radiation characteristics of 13 × 13 CP transparent reflectarray antenna are investigated. A circularly polarized horn antenna is used to feed the reflectarray. The solar cell is incorporated with the transparent reflectarray on the same area. The solar-cell integration with the reflectarray reduces the maximum gain by about 0.5 dB due to the increase in the magnitude of the reflection coefficient. The results are calculated using the finite integral technique (FIT.

  12. Shaping the mammalian auditory sensory organ by the planar cell polarity pathway. (United States)

    Kelly, Michael; Chen, Ping


    The human ear is capable of processing sound with a remarkable resolution over a wide range of intensity and frequency. This ability depends largely on the extraordinary feats of the hearing organ, the organ of Corti and its sensory hair cells. The organ of Corti consists of precisely patterned rows of sensory hair cells and supporting cells along the length of the snail-shaped cochlear duct. On the apical surface of each hair cell, several rows of actin-containing protrusions, known as stereocilia, form a "V"-shaped staircase. The vertices of all the "V"-shaped stereocilia point away from the center of the cochlea. The uniform orientation of stereocilia in the organ of Corti manifests a distinctive form of polarity known as planar cell polarity (PCP). Functionally, the direction of stereociliary bundle deflection controls the mechanical channels located in the stereocilia for auditory transduction. In addition, hair cells are tonotopically organized along the length of the cochlea. Thus, the uniform orientation of stereociliary bundles along the length of the cochlea is critical for effective mechanotransduction and for frequency selection. Here we summarize the morphological and molecular events that bestow the structural characteristics of the mammalian hearing organ, the growth of the snail-shaped cochlear duct and the establishment of PCP in the organ of Corti. The PCP of the sensory organs in the vestibule of the inner ear will also be described briefly.

  13. Twinstar, the Drosophila homolog of cofilin/ADF, is required for planar cell polarity patterning. (United States)

    Blair, Adrienne; Tomlinson, Andrew; Pham, Hung; Gunsalus, Kristin C; Goldberg, Michael L; Laski, Frank A


    Planar cell polarity (PCP) is a level of tissue organization in which cells adopt a uniform orientation within the plane of an epithelium. The process of tissue polarization is likely to be initiated by an extracellular gradient. Thus, determining how cells decode and convert this graded information into subcellular asymmetries is key to determining how cells direct the reorganization of the cytoskeleton to produce uniformly oriented structures. Twinstar (Tsr), the Drosophila homolog of Cofilin/ADF (actin depolymerization factor), is a component of the cytoskeleton that regulates actin dynamics. We show here that various alleles of tsr produce PCP defects in the wing, eye and several other epithelia. In wings mutant for tsr, Frizzled (Fz) and Flamingo (Fmi) proteins do not properly localize to the proximodistal boundaries of cells. The correct asymmetric localization of these proteins instructs the actin cytoskeleton to produce one actin-rich wing hair at the distal-most vertex of each cell. These results argue that actin remodeling is not only required in the manufacture of wing hairs, but also in the PCP read-out that directs where a wing hair will be secreted.

  14. NKp46 clusters at the immune synapse and regulates NK cell polarization

    Directory of Open Access Journals (Sweden)

    Uzi eHadad


    Full Text Available Natural killer cells play an important role in first-line defense against tumor and virus-infected cells. The activity of NK cells is tightly regulated by a repertoire of cell-surface expressed inhibitory and activating receptors. NKp46 is a major NK cell activating receptor that is involved in the elimination of target cells. NK cells form different types of synapses that result in distinct functional outcomes: cytotoxic, inhibitory, and regulatory. Recent studies revealed that complex integration of NK receptor signaling controls cytoskeletal rearrangement and other immune synapse-related events. However the distinct nature by which NKp46 participates in NK immunological synapse formation and function remains unknown. In this study we determined that NKp46 forms microclusters structures at the immune synapse between NK cells and target cells. Over-expression of human NKp46 is correlated with increased accumulation of F-actin mesh at the immune synapse. Concordantly, knock-down of NKp46 in primary human NK cells decreased recruitment of F-actin to the synapse. Live cell imaging experiments showed a linear correlation between NKp46 expression and lytic granules polarization to the immune synapse. Taken together, our data suggest that NKp46 signaling directly regulates the NK lytic immune synapse from early formation to late function.

  15. Hypoxic pretreatment of human umbilical cord mesenchymal stem cells regulating macrophage polarization

    Directory of Open Access Journals (Sweden)

    Chuan TONG


    Full Text Available Objective  To investigate the effect of human umbilical cord mesenchymal stem cells (hUC-MSCs on macrophage polarization under hypoxia. Methods  hUC-MSCs were obtained by explants adherent culture and cultured under normoxia (21% O2 and hypoxia (5% O2. The multi-directional differentiation of hUC-MSCs was observed by osteogenic and adipogenic differentiation induction. Live/death staining was performed to detect the cell viability, and ELISA was executed to detect the protein content in supernatant of hUC-MSCs. Transwell chamber was employed to co-culture the hUC-MSCs cultured under normoxia and hypoxia and macrophage (THP-1 stimulated by lipopolysaccharide (IPS, then the polarization of THP-1 was detected by immunofluorescence, and the secretions of inflammatory factor and anti-inflammatory factor of THP-1 were detected by ELISA. Results  hUC-MSCs cultured under hypoxia showed the ability of osteogenic and adipogenic multi-directional differentiation. Live/death staining showed the high cell viability of hUC-MSCs cultured under normoxia and hypoxia. The expression levels of prostaglandin E2 (PGE2 and indoleamine 2,3-dioxygenase (IDO were significantly higher in the hUC-MSCs cultured under hypoxia than in those cultured under normoxia. hUCMSCs cultured under hypoxia promoted the polarization of THP-1 to M2, obviously reduced the expression of TNF-α and IL-1β, and increased the expression of IL-10 significantly. Conclusion hUC-MSCs cultured under hypoxia may promote the polarization of THP-1 to M2 and improve the viability of anti-inflammatory. DOI: 10.11855/j.issn.0577-7402.2016.07.01

  16. Interaction of motility, directional sensing, and polarity modules recreates the behaviors of chemotaxing cells.

    Directory of Open Access Journals (Sweden)

    Changji Shi

    Full Text Available Chemotaxis involves the coordinated action of separable but interrelated processes: motility, gradient sensing, and polarization. We have hypothesized that these are mediated by separate modules that account for these processes individually and that, when combined, recreate most of the behaviors of chemotactic cells. Here, we describe a mathematical model where the modules are implemented in terms of reaction-diffusion equations. Migration and the accompanying changes in cellular morphology are demonstrated in simulations using a mechanical model of the cell cortex implemented in the level set framework. The central module is an excitable network that accounts for random migration. The response to combinations of uniform stimuli and gradients is mediated by a local excitation, global inhibition module that biases the direction in which excitability is directed. A polarization module linked to the excitable network through the cytoskeleton allows unstimulated cells to move persistently and, for cells in gradients, to gradually acquire distinct sensitivity between front and back. Finally, by varying the strengths of various feedback loops in the model we obtain cellular behaviors that mirror those of genetically altered cell lines.

  17. Dystroglycan loss disrupts polarity and beta-casein induction inmammary epithelial cells by perturbing laminin anchoring

    Energy Technology Data Exchange (ETDEWEB)

    Weir, M. Lynn; Oppizzi, Maria Luisa; Henry, Michael D.; Onishi,Akiko; Campbell, Kevin P.; Bissell, Mina J.; Muschler, John L.


    Precise contact between epithelial cells and their underlying basement membrane is critical to the maintenance of tissue architecture and function. To understand the role that the laminin receptor dystroglycan (DG) plays in these processes, we assayed cell responses to laminin-111 following conditional ablation of DG expression in cultured mammary epithelial cells (MECs). Strikingly, DG loss disrupted laminin-111-induced polarity and {beta}-casein production, and abolished laminin assembly at the step of laminin binding to the cell surface. DG re-expression restored these deficiencies. Investigations of mechanism revealed that DG cytoplasmic sequences were not necessary for laminin assembly and signaling, and only when the entire mucin domain of extracellular DG was deleted did laminin assembly not occur. These results demonstrate that DG is essential as a laminin-111 co-receptor in MECs that functions by mediating laminin anchoring to the cell surface, a process that allows laminin polymerization, tissue polarity, and {beta}-casein induction. The observed loss of laminin-111 assembly and signaling in DG-/-MECs provides insights into the signaling changes occurring in breast carcinomas and other cancers, where DG's laminin-binding function is frequently defective.

  18. Mycobacterium tuberculosislpdC, Rv0462, induces dendritic cell maturation and Th1 polarization

    Energy Technology Data Exchange (ETDEWEB)

    Heo, Deok Rim [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Shin, Sung Jae; Kim, Woo Sik [Department of Microbiology, College of Medicine, Chungnam National University, Munwha-Dong, Jung-Ku, Daejeon 301-747 (Korea, Republic of); Noh, Kyung Tae; Park, Jin Wook; Son, Kwang Hee [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Park, Won Sun [Department of Physiology, Kangwon National University, School of Medicine, Chuncheon 200-701 (Korea, Republic of); Lee, Min-Goo [Department of Physiology, Korea University, College of Medicine, Anam-dong, Sungbuk-Gu, Seoul 136-705 (Korea, Republic of); Kim, Daejin [Department of Anatomy, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Shin, Yong Kyoo [Department of Pharmacology, Chung-Ang University, College of Medicine, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Jung, In Duk, E-mail: [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Park, Yeong-Min, E-mail: [Department of Microbiology and Immunology, School of Medicine, Pusan National University, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of); Research Institute of Convergence of Biomedical Science and Technology, Pusan National University Yangsan Hospital, Beom-eo Ri, Mulgum Eop, Yangsan, Gyeongsangnam-do 626-770 (Korea, Republic of)


    Highlights: {yields} Treatment with Rv0462 induces the expression of surface molecules and the production of cytokines in DCs. {yields} Rv0462 induces the activation of MAPKs. {yields} Rv0462-treated DCs enhances the proliferation of CD4{sup +} T cells. -- Abstract: Mycobacterium tuberculosis, the etiological factor of pulmonary tuberculosis, causes significant morbidity and mortality worldwide. Activation of host immune responses for containment of mycobacterial infections involves participation of innate immune cells, such as dendritic cells (DCs). In this study, we demonstrated that the gene encoding lipoamide dehydrogenase C (lpdC) from M. tuberculosis, Rv0462, induce maturation and activation of DCs involved in the MAPKs signaling pathway. Moreover, Rv0462-treated DCs activated naive T cells, polarized CD4{sup +} and CD8{sup +} T cells to secrete IFN-{gamma} in syngeneic mixed lymphocyte reactions, which would be expected to contribute to Th1 polarization of the immune response. Our results suggest that Rv0462 can contribute to the innate and adaptive immune responses during tuberculosis infection, and thus modulate the clinical course of tuberculosis.

  19. Inhibition of planar cell polarity extends neural growth during regeneration, homeostasis, and development. (United States)

    Beane, Wendy S; Tseng, Ai-Sun; Morokuma, Junji; Lemire, Joan M; Levin, Michael


    The ability to stop producing or replacing cells at the appropriate time is essential, as uncontrolled growth can lead to loss of function and even cancer. Tightly regulated mechanisms coordinate the growth of stem cell progeny with the patterning needs of the host organism. Despite the importance of proper termination during regeneration, cell turnover, and embryonic development, very little is known about how tissues determine when patterning is complete during these processes. Using planarian flatworms, we show that the planar cell polarity (PCP) pathway is required to stop the growth of neural tissue. Although traditionally studied as regulators of tissue polarity, we found that loss of the PCP genes Vangl2, DAAM1, and ROCK by RNA interference (individually or together) resulted in supernumerary eyes and excess optical neurons in intact planarians, while regenerating planarians had continued hyperplasia throughout the nervous system long after controls ceased new growth. This failure to terminate growth suggests that neural tissues use PCP as a readout of patterning, highlighting a potential role for intact PCP as a signal to stem and progenitor cells to halt neuronal growth when patterning is finished. Moreover, we found this mechanism to be conserved in vertebrates. Loss of Vangl2 during normal development, as well as during Xenopus tadpole tail regeneration, also leads to the production of excess neural tissue. This evolutionarily conserved function of PCP represents a tractable new approach for controlling the growth of nerves.

  20. Viral protein determinants of Lassa virus entry and release from polarized epithelial cells. (United States)

    Schlie, Katrin; Maisa, Anna; Freiberg, Fabian; Groseth, Allison; Strecker, Thomas; Garten, Wolfgang


    The epithelium plays a key role in the spread of Lassa virus. Transmission from rodents to humans occurs mainly via inhalation or ingestion of droplets, dust, or food contaminated with rodent urine. Here, we investigated Lassa virus infection in cultured epithelial cells and subsequent release of progeny viruses. We show that Lassa virus enters polarized Madin-Darby canine kidney (MDCK) cells mainly via the basolateral route, consistent with the basolateral localization of the cellular Lassa virus receptor alpha-dystroglycan. In contrast, progeny virus was efficiently released from the apical cell surface. Further, we determined the roles of the glycoprotein, matrix protein, and nucleoprotein in directed release of nascent virus. To do this, a virus-like-particle assay was developed in polarized MDCK cells based on the finding that, when expressed individually, both the glycoprotein GP and matrix protein Z form virus-like particles. We show that GP determines the apical release of Lassa virus from epithelial cells, presumably by recruiting the matrix protein Z to the site of virus assembly, which is in turn essential for nucleocapsid incorporation into virions.

  1. Highly polarized Th17 cells induce EAE via a T-bet independent mechanism. (United States)

    Grifka-Walk, Heather M; Lalor, Stephen J; Segal, Benjamin M


    In the MOG35-55 induced EAE model, autoreactive Th17 cells that accumulate in the central nervous system acquire Th1 characteristics via a T-bet dependent mechanism. It remains to be determined whether Th17 plasticity and encephalitogenicity are causally related to each other. Here, we show that IL-23 polarized T-bet(-/-) Th17 cells are unimpaired in either activation or proliferation, and induce higher quantities of the chemokines RANTES and CXCL2 than WT Th17 cells. Unlike their WT counterparts, T-bet(-/-) Th17 cells retain an IL-17(hi) IFN-γ(neg-lo) cytokine profile following adoptive transfer into syngeneic hosts. This population of highly polarized Th17 effectors is capable of mediating EAE, albeit with a milder clinical course. It has previously been reported that the signature Th1 and Th17 effector cytokines, IFN-γ and IL-17, are dispensable for the development of autoimmune demyelinating disease. The current study demonstrates that the "master regulator" transcription factor, T-bet, is also not universally required for encephalitogenicity. Our results contribute to a growing body of data showing heterogeneity of myelin-reactive T cells and the independent mechanisms they employ to inflict damage to central nervous system tissues, complicating the search for therapeutic targets relevant across the spectrum of individuals with multiple sclerosis.

  2. The core planar cell polarity gene prickle interacts with flamingo to promote sensory axon advance in the Drosophila embryo. (United States)

    Mrkusich, Eli M; Flanagan, Dustin J; Whitington, Paul M


    The atypical cadherin Drosophila protein Flamingo and its vertebrate homologues play widespread roles in the regulation of both dendrite and axon growth. However, little is understood about the molecular mechanisms that underpin these functions. Whereas flamingo interacts with a well-defined group of genes in regulating planar cell polarity, previous studies have uncovered little evidence that the other core planar cell polarity genes are involved in regulation of neurite growth. We present data in this study showing that the planar cell polarity gene prickle interacts with flamingo in regulating sensory axon advance at a key choice point - the transition between the peripheral nervous system and the central nervous system. The cytoplasmic tail of the Flamingo protein is not required for this interaction. Overexpression of another core planar cell polarity gene dishevelled produces a similar phenotype to prickle mutants, suggesting that this gene may also play a role in regulation of sensory axon advance.

  3. Kermit interacts with Gαo, Vang, and motor proteins in Drosophila planar cell polarity.

    Directory of Open Access Journals (Sweden)

    Chen Lin

    Full Text Available In addition to the ubiquitous apical-basal polarity, epithelial cells are often polarized within the plane of the tissue--the phenomenon known as planar cell polarity (PCP. In Drosophila, manifestations of PCP are visible in the eye, wing, and cuticle. Several components of the PCP signaling have been characterized in flies and vertebrates, including the heterotrimeric Go protein. However, Go signaling partners in PCP remain largely unknown. Using a genetic screen we uncover Kermit, previously implicated in G protein and PCP signaling, as a novel binding partner of Go. Through pull-down and genetic interaction studies, we find that Kermit interacts with Go and another PCP component Vang, known to undergo intracellular relocalization during PCP establishment. We further demonstrate that the activity of Kermit in PCP differentially relies on the motor proteins: the microtubule-based dynein and kinesin motors and the actin-based myosin VI. Our results place Kermit as a potential transducer of Go, linking Vang with motor proteins for its delivery to dedicated cellular compartments during PCP establishment.

  4. FO Aqr time keeping

    CERN Document Server

    Bonnardeau, Michel


    Twelve seasons, from 2004 to 2015, of photometric monitoring of the intermediate polar FO Aqr are presented and are compared with previous observations. The ambiguities in the cycle counting can be lifted and a new O-C diagram, spanning 34 yr, is presented, along with new ephemerides.

  5. AO Psc time keeping (United States)

    Bonnardeau, Michel


    Eleven seasons, from 2004 to 2014, of photometric monitoring of the intermediate polar AO Psc are presented and are compared with previous observations. The spin up of the white dwarf is found to be slowing down. The amplitudes of the modulated and non-modulated components of the brightness are found to have undergone a major change in 2007.

  6. The storage cell of the polarized H/D internal gas target of the HERMES experiment at HERA

    CERN Document Server

    Baumgarten, C; Carassiti, V; Ciullo, G; Court, G; Dalpiaz, P F; Garutti, E; Golendukhin, A; Graw, G; Haeberli, W; Henoch, M; Hertenberger, R; Koch, N; Kolster, H; Lenisa, P; Marukyan, H; Nass, A; Reggiani, D; Rith, K; Stancari, M; Steffens, E; Stewart, J; Wise, T


    The storage cell of the internal, longitudinally polarized, atomic gas target of the Hermes experiment is presented. The polarized atoms of hydrogen or deuterium are accumulated in an open-ended thin walled storage cell through which the circulating electron or positron beam of the HERA accelerator passes. The target areal density is 10 sup 1 sup 4 atoms/cm sup 2 , two orders of magnitude larger than without the cell. The construction details of the cell are described and the cell's performance during HERMES run of 1997-2000 is discussed.

  7. Coupling of cytoplasm and adhesion dynamics determines cell polarization and locomotion

    CERN Document Server

    Bock, Martin; Möhl, Christoph


    Observations of single epidermal cells on flat adhesive substrates have revealed two distinct morphological and functional states, namely a non-migrating symmetric unpolarized state and a migrating asymmetric polarized state. These states are characterized by different spatial distributions and dynamics of important biochemical cell components: F-actin and myosin-II form the contractile part of the cytoskeleton, and integrin receptors in the plasma membrane connect F-actin filaments to the substratum. In this way, focal adhesion complexes are assembled, which determine cytoskeletal force transduction and subsequent cell locomotion. So far, physical models have reduced this phenomenon either to gradients in regulatory control molecules or to different mechanics of the actin filament system in different regions of the cell. Here we offer an alternative and self-organizational model incorporating polymerization, pushing and sliding of filaments, as well as formation of adhesion sites and their force dependent ki...

  8. Cancer-associated fibroblasts as another polarized cell type of the tumor microenvironment

    Directory of Open Access Journals (Sweden)

    Martin eAugsten


    Full Text Available Tumor- or cancer-associated fibroblasts (CAFs are one of the most abundant stromal cell types in different carcinomas and comprise a heterogeneous cell population. Classically, CAFs are assigned with pro-tumorigenic effects stimulating tumor growth and progression. More recent studies demonstrated also tumor-inhibitory effects of CAFs suggesting that tumor-residing fibroblasts exhibit a similar degree of plasticity as other stromal cell types. Reciprocal interactions with the tumor milieu and different sources of origin are emerging as two important factors underlying CAF heterogeneity. This review highlights recent advances in our understanding of CAF biology and proposes to expand the term of cellular ´polarization´, previously introduced to describe different activation states of various immune cells, onto CAFs to reflect their phenotypic diversity.

  9. Cells and Yin-Yang polarity- (Towards greater similarity between the animate and the inanimate

    Directory of Open Access Journals (Sweden)

    Kothari M


    Full Text Available A cell-plant or animal-is proving a bioelectric wonder al-ready boasting of pyro-, piezo-, ferroelectricity, solid state and electretism as eminent exhibits and probable functional mechan-isms. A cell, its parts, and its products owe the bioelectric boon to inherent and universal polarity pregnant with dipolar electro-magnetic moment. The cytologic bipolarity prompts a hypothesis that the cell and its world may be no exception to the working of Yin-Yang, the Taoistic concept o f all-pervading reality. Nuclear, cytoplasmic, gametic and zygotic considerations compellingly suggest that Yin-Yang does prevail, making us and′ our cells basically field-effects, thus erasing further the distinction between male and female, animate and inanimate, biomass and bioenergy.

  10. The planar cell polarity protein Vangl2 is involved in postsynaptic compartmentalization. (United States)

    Nagaoka, Tadahiro; Kishi, Masashi


    The excitatory postsynaptic region of the vertebrate hippocampus is usually compartmentalized into the postsynaptic density (PSD) and N-cadherin-rich domain, which is important for synaptic adhesion. However, the molecular mechanisms underlying the compartment formation are unknown. In the present report, we show that the planar cell polarity (PCP) protein Van Gogh-like 2 (Vangl2) plays a role in this regionalization. In cultured rat hippocampal neurons that were subjected to Vangl2 expression silencing, the formed clusters of PSD-95, one of the major scaffolding proteins in PSD, tended to overlap with those of N-cadherin. Further, in the dendrites of these neurons, the immunofluorescence of PSD-95 was to some extent diffused, without a significant change in the total signal. Because Vangl2 physically interacts with both PSD-95 and N-cadherin in vivo, these results suggest that a PCP-related direct molecular mechanism underlies the horizontal polarization of the postsynaptic regions.

  11. SOLID OXIDE FUEL CELL CATHODES: Polarization Mechanisms and Modeling of the Electrochemical Performance (United States)

    Fleig, Jurgen


    Several recent experimental and numerical investigations have contributed to the improved understanding of the electrochemical mechanisms taking place at solid oxide fuel cell (SOFC) cathodes and yielded valuable information on the relationships between alterable parameters (geometry/material) and the cathodic polarization resistance. Efforts to reduce the polarization resistance in SOFCs can benefit from these results, and some important aspects of the corresponding studies are reviewed. Experimental results, particularly measurements using geometrically well-defined Sr-doped LaMnO3 (LSM) cathodes, are discussed. In regard to simulations, the different levels of sophistication used in SOFC electrode modeling studies are summarized and compared. Exemplary simulations of mixed conducting cathodes that show the capabilities and limits of different modeling levels are described.

  12. Calponin 2 Acts As an Effector of Noncanonical Wnt-Mediated Cell Polarization during Neural Crest Cell Migration

    Directory of Open Access Journals (Sweden)

    Bärbel Ulmer


    Full Text Available Neural crest cells (NCCs migrate throughout the embryo to differentiate into cell types of all germ layers. Initial directed NCC emigration relies on planar cell polarity (PCP, which through the activity of the small GTPases RhoA and Rac governs the actin-driven formation of polarized cell protrusions. We found that the actin binding protein calponin 2 (Cnn2 was expressed in protrusions at the leading edge of migratory NCCs in chicks and frogs. Cnn2 knockdown resulted in NCC migration defects in frogs and chicks and randomized outgrowth of cell protrusions in NCC explants. Morphant cells showed central stress fibers at the expense of the peripheral actin network. Cnn2 acted downstream of Wnt/PCP, as migration defects induced by dominant-negative Wnt11 or inhibition of RhoA function were rescued by Cnn2 knockdown. These results suggest that Cnn2 modulates actin dynamics during NCC migration as an effector of noncanonical Wnt/PCP signaling.

  13. Effect of atomic noise on optical squeezing via polarization self-rotation in a thermal vapor cell

    DEFF Research Database (Denmark)

    Hsu, M.T.L.; Hetet, G.; Peng, A.


    show results of the characterization of PSR in isotopically enhanced rubidium-87 cells, performed in two independent laboratories. We observed that, contrary to earlier work, the presence of atomic noise in the thermal vapor overwhelms the observation of squeezing. We present a theory that contains......The traversal of an elliptically polarized optical field through a thermal vapor cell can give rise to a rotation of its polarization axis. This process, known as polarization self-rotation (PSR), has been suggested as a mechanism for producing squeezed light at atomic transition wavelengths. We...... atomic noise terms and show that a null result in squeezing is consistent with this theory....

  14. Structural polarity and dynamics of male germline stem cells in the milkweed bug (Oncopeltus fasciatus). (United States)

    Schmidt, Esther D; Dorn, August


    The male germline stem cells (GSCs) of the milkweed bug present an extraordinary structural polarity that is, to our knowledge, unequalled by any other type of stem cells. They consist of a perikaryon and numerous projections arising from the cell pole directed toward the apical cells, the proposed niche of the GSCs. The projections can traverse a considerable distance until their terminals touch the apical cells. From hatching until death, the GSC projections undergo conspicuous changes, the sequence of which has been deduced from observations of all developmental stages. Projection formation starts from lobular cell protrusions showing trabecular ingrowths of the cell membrane. Finger-like projections result from a process of growth and "carving out". The newly formed projections contain mostly only free ribosomes other than a few mitochondria. A stereotyped degradation process commences in the projection terminals: profiles of circular, often concentric, cisternae of rough endoplasmic reticulum appear and turn into myelin bodies, whereas mitochondria become more numerous. The cytoplasm vesiculates, lysosomal bodies appear, and mitochondria become swollen. At the same time, the projection terminals are segregated by transverse ingrowths of the cell membrane. Finally, autophagic vacuoles and myelin bodies fill the segregated terminals, which then rupture. Simultaneously, new projections seem to sprout from the perikaryon of the GSCs. These dynamics, which are not synchronized among the GSCs, indicate that a novel type of signal exchange and transduction between the stem cells and their niche is involved in the regulation of asymmetric versus symmetric division of GSCs.

  15. Hyaluronan synthesis is necessary for autoreactive T-cell trafficking, activation, and Th1 polarization. (United States)

    Kuipers, Hedwich F; Rieck, Mary; Gurevich, Irina; Nagy, Nadine; Butte, Manish J; Negrin, Robert S; Wight, Thomas N; Steinman, Lawrence; Bollyky, Paul L


    The extracellular matrix polysaccharide hyaluronan (HA) accumulates at sites of autoimmune inflammation, including white matter lesions in multiple sclerosis (MS), but its functional importance in pathogenesis is unclear. We have evaluated the impact of 4-methylumbelliferone (4-MU), an oral inhibitor of HA synthesis, on disease progression in the experimental autoimmune encephalomyelitis (EAE) mouse model of MS. Treatment with 4-MU decreases the incidence of EAE, delays its onset, and reduces the severity of established disease. 4-MU inhibits the activation of autoreactive T cells and prevents their polarization toward a Th1 phenotype. Instead, 4-MU promotes polarization toward a Th2 phenotpye and induction of Foxp3(+) regulatory T cells. Further, 4-MU hastens trafficking of T cells through secondary lymphoid organs, impairs the infiltration of T cells into the CNS parenchyma, and limits astrogliosis. Together, these data suggest that HA synthesis is necessary for disease progression in EAE and that treatment with 4-MU may be a potential therapeutic strategy in CNS autoimmunity. Considering that 4-MU is already a therapeutic, called hymecromone, that is approved to treat biliary spasm in humans, we propose that it could be repurposed to treat MS.

  16. Application of Butler-Volmer equations in the modelling of activation polarization for PEM fuel cells (United States)

    Mann, R. F.; Amphlett, J. C.; Peppley, B. A.; Thurgood, C. P.

    Proton exchange membrane (PEM) fuel cells have been under development for many years and appear to be the potential solution for many electricity supply applications. Modelling and computer simulation of PEM fuel cells have been equally active areas of work as a means of developing better understanding of cell and stack operation, facilitating design improvements and supporting system simulation studies. In general, fuel cell models must be capable of predicting values of the activation polarization at both the anode and the cathode. Since the magnitude of an activation polarization for a particular electrode depends on the inverse of the chemical (or electrochemical) reaction rate at that electrode, reaction rate expressions are normally required for each electrode. The reaction rate is commonly expressed as an 'exchange current density', typical symbol i 0, and mechanistic expressions to predict i 0 are, therefore, components of an ideal model. Most expressions for i 0 are based on the Butler-Volmer (B-V) equation or on more approximate equations derived from the B-V equation. Many publications use one of these B-V equations without a critical determination of the applicability or accuracy of the particular equation being used. The present paper examines these questions and makes some recommendations regarding the applicability of each equation in the 'B-V family of equations'. In addition, terminology and symbols have been modified, where possible, to make modelling based on B-V equations more easily understood and applied by those without an extensive background in electrochemistry.

  17. GRHL2 coordinates regeneration of a polarized mucociliary epithelium from basal stem cells. (United States)

    Gao, Xia; Bali, Aman S; Randell, Scott H; Hogan, Brigid L M


    Pseudostratified airway epithelium of the lung is composed of polarized ciliated and secretory cells maintained by basal stem/progenitor cells. An important question is how lineage choice and differentiation are coordinated with apical-basal polarity and epithelial morphogenesis. Our previous studies indicated a key integrative role for the transcription factor Grainyhead-like 2 (Grhl2). In this study, we present further evidence for this model using conditional gene deletion during the regeneration of airway epithelium and clonal organoid culture. We also use CRISPR/Cas9 genome editing in primary human basal cells differentiating into organoids and mucociliary epithelium in vitro. Loss of Grhl2 inhibits organoid morphogenesis and the differentiation of ciliated cells and reduces the expression of both notch and ciliogenesis genes (Mcidas, Rfx2, and Myb) with distinct Grhl2 regulatory sites. The genome editing of other putative target genes reveals roles for zinc finger transcription factor Znf750 and small membrane adhesion glycoprotein in promoting ciliogenesis and barrier function as part of a network of genes coordinately regulated by Grhl2.

  18. A Molecular Probe for the Detection of Polar Lipids in Live Cells (United States)

    Bader, Christie A.; Shandala, Tetyana; Carter, Elizabeth A.; Ivask, Angela; Guinan, Taryn; Hickey, Shane M.; Werrett, Melissa V.; Wright, Phillip J.; Simpson, Peter V.; Stagni, Stefano; Voelcker, Nicolas H.; Lay, Peter A.; Massi, Massimiliano; Brooks, Douglas A.


    Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular

  19. A Molecular Probe for the Detection of Polar Lipids in Live Cells. (United States)

    Bader, Christie A; Shandala, Tetyana; Carter, Elizabeth A; Ivask, Angela; Guinan, Taryn; Hickey, Shane M; Werrett, Melissa V; Wright, Phillip J; Simpson, Peter V; Stagni, Stefano; Voelcker, Nicolas H; Lay, Peter A; Massi, Massimiliano; Plush, Sally E; Brooks, Douglas A


    Lipids have an important role in many aspects of cell biology, including membrane architecture/compartment formation, intracellular traffic, signalling, hormone regulation, inflammation, energy storage and metabolism. Lipid biology is therefore integrally involved in major human diseases, including metabolic disorders, neurodegenerative diseases, obesity, heart disease, immune disorders and cancers, which commonly display altered lipid transport and metabolism. However, the investigation of these important cellular processes has been limited by the availability of specific tools to visualise lipids in live cells. Here we describe the potential for ReZolve-L1™ to localise to intracellular compartments containing polar lipids, such as for example sphingomyelin and phosphatidylethanolamine. In live Drosophila fat body tissue from third instar larvae, ReZolve-L1™ interacted mainly with lipid droplets, including the core region of these organelles. The presence of polar lipids in the core of these lipid droplets was confirmed by Raman mapping and while this was consistent with the distribution of ReZolve-L1™ it did not exclude that the molecular probe might be detecting other lipid species. In response to complete starvation conditions, ReZolve-L1™ was detected mainly in Atg8-GFP autophagic compartments, and showed reduced staining in the lipid droplets of fat body cells. The induction of autophagy by Tor inhibition also increased ReZolve-L1™ detection in autophagic compartments, whereas Atg9 knock down impaired autophagosome formation and altered the distribution of ReZolve-L1™. Finally, during Drosophila metamorphosis fat body tissues showed increased ReZolve-L1™ staining in autophagic compartments at two hours post puparium formation, when compared to earlier developmental time points. We concluded that ReZolve-L1™ is a new live cell imaging tool, which can be used as an imaging reagent for the detection of polar lipids in different intracellular

  20. The Wnt receptor Ryk plays a role in mammalian planar cell polarity signaling. (United States)

    Macheda, Maria L; Sun, Willy W; Kugathasan, Kumudhini; Hogan, Benjamin M; Bower, Neil I; Halford, Michael M; Zhang, You Fang; Jacques, Bonnie E; Lieschke, Graham J; Dabdoub, Alain; Stacker, Steven A


    Wnts are essential for a wide range of developmental processes, including cell growth, division, and differentiation. Some of these processes signal via the planar cell polarity (PCP) pathway, which is a β-catenin-independent Wnt signaling pathway. Previous studies have shown that Ryk, a member of the receptor tyrosine kinase family, can bind to Wnts. Ryk is required for normal axon guidance and neuronal differentiation during development. Here, we demonstrate that mammalian Ryk interacts with the Wnt/PCP pathway. In vitro analysis showed that the Wnt inhibitory factor domain of Ryk was necessary for Wnt binding. Detailed analysis of two vertebrate model organisms showed Ryk phenotypes consistent with PCP signaling. In zebrafish, gene knockdown using morpholinos revealed a genetic interaction between Ryk and Wnt11 during the PCP pathway-regulated process of embryo convergent extension. Ryk-deficient mouse embryos displayed disrupted polarity of stereociliary hair cells in the cochlea, a characteristic of disturbed PCP signaling. This PCP defect was also observed in mouse embryos that were double heterozygotes for Ryk and Looptail (containing a mutation in the core Wnt/PCP pathway gene Vangl2) but not in either of the single heterozygotes, suggesting a genetic interaction between Ryk and Vangl2. Co-immunoprecipitation studies demonstrated that RYK and VANGL2 proteins form a complex, whereas RYK also activated RhoA, a downstream effector of PCP signaling. Overall, our data suggest an important role for Ryk in Wnt/planar cell polarity signaling during vertebrate development via the Vangl2 signaling pathway, as demonstrated in the mouse cochlea.

  1. Inversin/Nephrocystin-2 is required for fibroblast polarity and directional cell migration.

    Directory of Open Access Journals (Sweden)

    Iben R Veland

    Full Text Available Inversin is a ciliary protein that critically regulates developmental processes and tissue homeostasis in vertebrates, partly through the degradation of Dishevelled (Dvl proteins to coordinate Wnt signaling in planar cell polarity (PCP. Here, we investigated the role of Inversin in coordinating cell migration, which highly depends on polarity processes at the single-cell level, including the spatial and temporal organization of the cytoskeleton as well as expression and cellular localization of proteins in leading edge formation of migrating cells. Using cultures of mouse embryonic fibroblasts (MEFs derived from inv(-/- and inv(+/+ animals, we confirmed that both inv(-/- and inv(+/+ MEFs form primary cilia, and that Inversin localizes to the primary cilium in inv(+/+ MEFs. In wound healing assays, inv(-/- MEFs were severely compromised in their migratory ability and exhibited cytoskeletal rearrangements, including distorted lamellipodia formation and cilia orientation. Transcriptome analysis revealed dysregulation of Wnt signaling and of pathways regulating actin organization and focal adhesions in inv(-/- MEFs as compared to inv(+/+ MEFs. Further, Dvl-1 and Dvl-3 localized to MEF primary cilia, and β-catenin/Wnt signaling was elevated in inv(-/- MEFs, which moreover showed reduced ciliary localization of Dvl-3. Finally, inv(-/- MEFs displayed dramatically altered activity and localization of RhoA, Rac1, and Cdc42 GTPases, and aberrant expression and targeting of the Na(+/H(+ exchanger NHE1 and ezrin/radixin/moesin (ERM proteins to the edge of cells facing the wound. Phosphorylation of β-catenin at the ciliary base and formation of well-defined lamellipodia with localization and activation of ERM to the leading edge of migrating cells were restored in inv(-/- MEFs expressing Inv-GFP. Collectively, our findings point to the significance of Inversin in controlling cell migration processes, at least in part through transcriptional regulation of

  2. Keeping Enceladus warm (United States)

    Travis, B. J.; Schubert, G.


    Despite its small size, Enceladus emits considerable heat, especially at its south pole, even long after simple thermal models predict it should be frozen. Several sources of energy have been proposed as responsible for this heating, such as tidal dissipative heating (TDH), convection and shearing in the ice shell, and exothermic chemical reactions (e.g., serpentine formation). Crater relaxation simulations suggest that episodic heating events have occurred over long stretches of Enceladus' history. Thermal history and hydrothermal simulations reported here show that a combination of steady plus episodic TDH heating could maintain at least a polar ocean to the present time. Hydrothermal circulation can play a significant role in mining Enceladus' internal heat, facilitating the persistence of an ocean even to the present by focusing internal heat to the polar regions.

  3. Rearrangements between differentiating hair cells coordinate planar polarity and the establishment of mirror symmetry in lateral-line neuromasts

    Directory of Open Access Journals (Sweden)

    Ivana Mirkovic


    In addition to their ubiquitous apical-basal polarity, many epithelia are also polarized along an orthogonal axis, a phenomenon termed planar cell polarity (PCP. In the mammalian inner ear and the zebrafish lateral line, PCP is revealed through the orientation of mechanosensitive hair cells relative to each other and to the body axes. In each neuromast, the receptor organ of the lateral line, hair bundles are arranged in a mirror-symmetrical fashion. Here we show that the establishment of mirror symmetry is preceded by rotational rearrangements between hair-cell pairs, a behavior consistently associated with the division of hair-cell precursors. Time-lapse imaging of trilobite mutants, which lack the core PCP constituent Vang-like protein 2 (Vangl2, shows that their misoriented hair cells correlate with misaligned divisions of hair-cell precursors and an inability to complete rearrangements accurately. Vangl2 is asymmetrically localized in the cells of the neuromast, a configuration required for accurate completion of rearrangements. Manipulation of Vangl2 expression or of Notch signaling results in a uniform hair-cell polarity, indicating that rearrangements refine neuromast polarity with respect to the body axes.

  4. Periplasmic Acid Stress Increases Cell Division Asymmetry (Polar Aging of Escherichia coli.

    Directory of Open Access Journals (Sweden)

    Michelle W Clark

    Full Text Available Under certain kinds of cytoplasmic stress, Escherichia coli selectively reproduce by distributing the newer cytoplasmic components to new-pole cells while sequestering older, damaged components in cells inheriting the old pole. This phenomenon is termed polar aging or cell division asymmetry. It is unknown whether cell division asymmetry can arise from a periplasmic stress, such as the stress of extracellular acid, which is mediated by the periplasm. We tested the effect of periplasmic acid stress on growth and division of adherent single cells. We tracked individual cell lineages over five or more generations, using fluorescence microscopy with ratiometric pHluorin to measure cytoplasmic pH. Adherent colonies were perfused continually with LBK medium buffered at pH 6.00 or at pH 7.50; the external pH determines periplasmic pH. In each experiment, cell lineages were mapped to correlate division time, pole age and cell generation number. In colonies perfused at pH 6.0, the cells inheriting the oldest pole divided significantly more slowly than the cells inheriting the newest pole. In colonies perfused at pH 7.50 (near or above cytoplasmic pH, no significant cell division asymmetry was observed. Under both conditions (periplasmic pH 6.0 or pH 7.5 the cells maintained cytoplasmic pH values at 7.2-7.3. No evidence of cytoplasmic protein aggregation was seen. Thus, periplasmic acid stress leads to cell division asymmetry with minimal cytoplasmic stress.

  5. New circular polarization selective surface concepts based on the Pierrot cell using printed circuit technology (United States)

    Lopez, Humberto Israel

    This M.A.Sc. thesis focuses on finding an alternative method of constructing a circular polarization selective surface (CPSS) based on the Pierrot cell using the standard printed circuit technology. This technique uses a folded flexible substrate, which enables the implementation of the 3D Pierrot cells on a single metal layer defined with precision printed circuit board techniques, without the need for metalized via holes. Different topologies of the CPSS are analyzed in order to make the CPSS more efficient in terms of bandwidth and independence on the direction of propagation of the incident wave. A left-hand CPSS is designed to illustrate the benefits of the proposed approach. The first approach is a simple Pierrot unit cell CPSS which is optimized to have good reflection and transmission coefficients. A prototype is built and then characterized in a test bench operating in the K-band. For the fabricated prototype, the transmission coefficients of plane waves at normal incidence in the right-hand and the left-hand circular polarizations are --0.48 dB and --24 dB respectively. The bandwidth for which the transmission coefficient of the incident left-handed incident wave is greater than --3 dB was of 17.6%. These results are in good agreement with simulations results obtained with HFSS. A second variant considered is a Pierrot cell with a series load in the middle segment. With this cell it is possible to equalize the frequencies giving a better operation in the right- and left-handed circular polarized waves. There is an improvement for the co-pol to cross-pol ratio for the RHCP waves of 10 dB at 20 GHz. The added load does not affect the performance for the left-hand circular polarization, as expected. The third modification is a Pierrot cell at 90 degrees. This cell is designed to allow the combination of two Pierrot cells working at different frequencies on the same substrate in order to increase the frequency bandwidth of the CPSS. Unfortunately, the axial

  6. Optimal matrix rigidity for stress-fibre polarization in stem cells (United States)

    Zemel, A.; Rehfeldt, F.; Brown, A. E. X.; Discher, D. E.; Safran, S. A.


    The shape and differentiated state of many cell types are highly sensitive to the rigidity of the microenvironment. The physical mechanisms involved, however, are unknown. Here, we present a theoretical model and experiments demonstrating that the alignment of stress fibres within stem cells is a non-monotonic function of matrix rigidity. We treat the cell as an active elastic inclusion in a surrounding matrix, allowing the actomyosin forces to polarize in response to elastic stresses developed in the cell. The theory correctly predicts the monotonic increase of the cellular forces with the matrix rigidity and the alignment of stress fibres parallel to the long axis of cells. We show that the anisotropy of this alignment depends non-monotonically on matrix rigidity and demonstrate it experimentally by quantifying the orientational distribution of stress fibres in stem cells. These findings offer physical insight into the sensitivity of stem-cell differentiation to tissue elasticity and, more generally, introduce a cell-type-specific parameter for actomyosin polarizability.

  7. Influence of polar solvents on photovoltaic performance of Monascusred dye-sensitized solar cell. (United States)

    Lee, Jae Wook; Kim, Tae Young; Ko, Hyun Seok; Han, Shin; Lee, Suk-Ho; Park, Kyung Hee


    Dye-sensitized solar cells (DSSCs) were assembled using natural dyes extracted from Monascus red pigment as a sensitizer. In this work, we studied the adsorption characteristics for harvesting sunlight and the electrochemical behavior for electron transfer in Monascus red DSSC using different solvents. The effect of polar aprotic and protic solvents including water, ethanol, and dimethylsulfoxide (DMSO) used in the sensitization process was investigated for the improvement in conversion efficiency of a cell. As for the Monascus red dye-sensitized electrode in DMSO solvent, the solar cell yields a short-circuit current density (Jsc) of 1.23mA/cm(2), a photovoltage (Voc) of 0.75V, and a fill factor of 0.72, corresponding to an energy conversion efficiency (η) of 0.66%.

  8. The Par3 polarity protein is an exocyst receptor essential for mammary cell survival (United States)

    Ahmed, Syed Mukhtar; Macara, Ian G.


    The exocyst is an essential component of the secretory pathway required for delivery of basolateral proteins to the plasma membranes of epithelial cells. Delivery occurs adjacent to tight junctions (TJ), suggesting that it recognizes a receptor at this location. However, no such receptor has been identified. The Par3 polarity protein associates with TJs but has no known function in membrane traffic. We now show that, unexpectedly, Par3 is essential for mammary cell survival. Par3 silencing causes apoptosis, triggered by phosphoinositide trisphosphate depletion and decreased Akt phosphorylation, resulting from failure of the exocyst to deliver basolateral proteins to the cortex. A small region of PAR3 binds directly to Exo70 and is sufficient for exocyst docking, membrane-protein delivery and cell survival. PAR3 lacking this domain can associate with the cortex but cannot support exocyst function. We conclude that Par3 is the long-sought exocyst receptor required for targeted membrane-protein delivery. PMID:28358000

  9. Influence of polar solvents on photovoltaic performance of Monascusred dye-sensitized solar cell (United States)

    Lee, Jae Wook; Kim, Tae Young; Ko, Hyun Seok; Han, Shin; Lee, Suk-Ho; Park, Kyung Hee

    Dye-sensitized solar cells (DSSCs) were assembled using natural dyes extracted from Monascus red pigment as a sensitizer. In this work, we studied the adsorption characteristics for harvesting sunlight and the electrochemical behavior for electron transfer in Monascus red DSSC using different solvents. The effect of polar aprotic and protic solvents including water, ethanol, and dimethylsulfoxide (DMSO) used in the sensitization process was investigated for the improvement in conversion efficiency of a cell. As for the Monascus red dye-sensitized electrode in DMSO solvent, the solar cell yields a short-circuit current density (Jsc) of 1.23 mA/cm2, a photovoltage (Voc) of 0.75 V, and a fill factor of 0.72, corresponding to an energy conversion efficiency (η) of 0.66%.

  10. Soluble CLEC2 Extracellular Domain Improves Glucose and Lipid Homeostasis by Regulating Liver Kupffer Cell Polarization

    Directory of Open Access Journals (Sweden)

    Xinle Wu


    Full Text Available The polarization of tissue resident macrophages toward the alternatively activated, anti-inflammatory M2 phenotype is believed to positively impact obesity and insulin resistance. Here we show that the soluble form of the extracellular domain (ECD of C-type lectin-like receptor 2, CLEC2, regulates Kupffer cell polarization in the liver and improves glucose and lipid parameters in diabetic animal models. Over-expression of Fc-CLEC2(ECD in mice via in vivo gene delivery, or injection of recombinant Fc-CLEC2(ECD protein, results in a reduction of blood glucose and liver triglyceride levels and improves glucose tolerance. Furthermore, Fc-CLEC2(ECD treatment improves cytokine profiles and increases both the M2 macrophage population and the genes involved in the oxidation of lipid metabolism in the liver. These data reveal a previously unidentified role for CLEC2 as a regulator of macrophage polarity, and establish CLEC2 as a promising therapeutic target for treatment of diabetes and liver disease.

  11. Gβ Regulates Coupling between Actin Oscillators for Cell Polarity and Directional Migration.

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    Oliver Hoeller


    Full Text Available For directional movement, eukaryotic cells depend on the proper organization of their actin cytoskeleton. This engine of motility is made up of highly dynamic nonequilibrium actin structures such as flashes, oscillations, and traveling waves. In Dictyostelium, oscillatory actin foci interact with signals such as Ras and phosphatidylinositol 3,4,5-trisphosphate (PIP3 to form protrusions. However, how signaling cues tame actin dynamics to produce a pseudopod and guide cellular motility is a critical open question in eukaryotic chemotaxis. Here, we demonstrate that the strength of coupling between individual actin oscillators controls cell polarization and directional movement. We implement an inducible sequestration system to inactivate the heterotrimeric G protein subunit Gβ and find that this acute perturbation triggers persistent, high-amplitude cortical oscillations of F-actin. Actin oscillators that are normally weakly coupled to one another in wild-type cells become strongly synchronized following acute inactivation of Gβ. This global coupling impairs sensing of internal cues during spontaneous polarization and sensing of external cues during directional motility. A simple mathematical model of coupled actin oscillators reveals the importance of appropriate coupling strength for chemotaxis: moderate coupling can increase sensitivity to noisy inputs. Taken together, our data suggest that Gβ regulates the strength of coupling between actin oscillators for efficient polarity and directional migration. As these observations are only possible following acute inhibition of Gβ and are masked by slow compensation in genetic knockouts, our work also shows that acute loss-of-function approaches can complement and extend the reach of classical genetics in Dictyostelium and likely other systems as well.

  12. KEEPING Exploring New Frontiers

    Institute of Scientific and Technical Information of China (English)

    Yan Manman


    @@ "To live fully is to surge ahead constantly. After achieving what you have aimed at, you should aim higher.Therefore, success doesn't mean what level you are at, but the journey of achieving next level". This is the meaning of success in the eyes of Guy Lam, Chairman of Pacrim International Capital Inc, Over 20 years since he began to engage in business, He has been keeping it in mind that the value of life lies in the journey to new creation but not the level of ownership. Therefore, when he achieved one success after another in different fields, Guy was never content with the achievement he had obtained.but more eager to explore new frontiers.

  13. Dishevelled is essential for neural connectivity and planar cell polarity in planarians. (United States)

    Almuedo-Castillo, Maria; Saló, Emili; Adell, Teresa


    The Wingless/Integrated (Wnt) signaling pathway controls multiple events during development and homeostasis. It comprises multiple branches, mainly classified according to their dependence on β-catenin activation. The Wnt/β-catenin branch is essential for the establishment of the embryonic anteroposterior (AP) body axis throughout the phylogenetic tree. It is also required for AP axis establishment during planarian regeneration. Wnt/β-catenin-independent signaling encompasses several different pathways, of which the most extensively studied is the planar cell polarity (PCP) pathway, which is responsible for planar polarization of cell structures within an epithelial sheet. Dishevelled (Dvl) is the hub of Wnt signaling because it regulates and channels the Wnt signal into every branch. Here, we analyze the role of Schmidtea mediterranea Dvl homologs (Smed-dvl-1 and Smed-dvl-2) using gene silencing. We demonstrate that in addition to a role in AP axis specification, planarian Dvls are involved in at least two different β-catenin-independent processes. First, they are essential for neural connectivity through Smed-wnt5 signaling. Second, Smed-dvl-2, together with the S. mediterranea homologs of Van-Gogh (Vang) and Diversin (Div), is required for apical positioning of the basal bodies of epithelial cells. These data represent evidence not only of the function of the PCP network in lophotrocozoans but of the involvement of the PCP core elements Vang and Div in apical positioning of the cilia.

  14. Evaluation of Planar-Cell-Polarity Phenotypes in Ciliopathy Mouse Mutant Cochlea. (United States)

    May-Simera, Helen


    In recent years, primary cilia have emerged as key regulators in development and disease by influencing numerous signaling pathways. One of the earliest signaling pathways shown to be associated with ciliary function was the non-canonical Wnt signaling pathway, also referred to as planar cell polarity (PCP) signaling. One of the best places in which to study the effects of planar cell polarity (PCP) signaling during vertebrate development is the mammalian cochlea. PCP signaling disruption in the mouse cochlea disrupts cochlear outgrowth, cellular patterning and hair cell orientation, all of which are affected by cilia dysfunction. The goal of this protocol is to describe the analysis of PCP signaling in the developing mammalian cochlea via phenotypic analysis, immunohistochemistry and scanning electron microscopy. Defects in convergence and extension are manifested as a shortening of the cochlear duct and/or changes in cellular patterning, which can be quantified following dissection from developing mouse mutants. Changes in stereociliary bundle orientation and kinocilia length or positioning can be observed and quantitated using either immunofluorescence or scanning electron microscopy (SEM). A deeper insight into the role of ciliary proteins in cellular signaling pathways and other biological phenomena is crucial for our understanding of cellular and developmental biology, as well as for the development of targeted treatment strategies.

  15. Role of the Polycystins in Cell Migration, Polarity, and Tissue Morphogenesis

    Directory of Open Access Journals (Sweden)

    Elisa Agnese Nigro


    Full Text Available Cystic kidney diseases (CKD is a class of disorders characterized by ciliary dysfunction and, therefore, belonging to the ciliopathies. The prototype CKD is autosomal dominant polycystic kidney disease (ADPKD, whose mutated genes encode for two membrane-bound proteins, polycystin-1 (PC-1 and polycystin-2 (PC-2, of unknown function. Recent studies on CKD-associated genes identified new mechanisms of morphogenesis that are central for establishment and maintenance of proper renal tubular diameter. During embryonic development in the mouse and lower vertebrates a convergent-extension (CE-like mechanism based on planar cell polarity (PCP and cellular intercalation is involved in “sculpting” the tubules into a narrow and elongated shape. Once the appropriate diameter is established, further elongation occurs through oriented cell division (OCD. The polycystins (PCs regulate some of these essential processes. In this review we summarize recent work on the role of PCs in regulating cell migration, the cytoskeleton, and front-rear polarity. These important properties are essential for proper morphogenesis of the renal tubules and the lymphatic vessels. We highlight here several open questions and controversies. Finally, we try to outline some of the next steps required to study these processes and their relevance in physiological and pathological conditions.

  16. JAM-A is both essential and inhibitory to development of hepatic polarity in WIF-B cells. (United States)

    Braiterman, Lelita T; Heffernan, Sean; Nyasae, Lydia; Johns, David; See, Alfred P; Yutzy, Rebeca; McNickle, Allison; Herman, Mira; Sharma, Arun; Naik, Ulhas P; Hubbard, Ann L


    Junctional adhesion molecule (JAM) is involved in tight junction (TJ) formation in epithelial cells. Three JAMs (A, B, and C) are expressed in rat hepatocytes, but only rat JAM-A is present in polarized WIF-B cells, a rat-human hepatic line. We used knockdown (KD) and overexpression in WIF-B cells to determine the role of JAM-A in the development of hepatic polarity. Expression of rat JAM-A short hairpin RNA resulted in approximately 50% KD of JAM-A and substantial loss of hepatic polarity, as measured by the absence of apical cysts formed by adjacent cells and sealed by TJ belts. When inhibitory RNA-resistant human JAM-A (huWT) was expressed in KD cells, hepatic polarity was restored. In contrast, expression of JAM-A that either lacked its PDZ-binding motif (huDeltaC-term) or harbored a point mutation (T273A) did not complement, indicating that multiple sites within JAM-A's cytoplasmic tail are required for the development of hepatic polarity. Overexpression of huWT in normal WIF-B cells unexpectedly blocked WIF-B maturation to the hepatic phenotype, as did expression of three huJAM-A constructs with single point mutations in putative phosphorylation sites. In contrast, huDeltaC-term was without effect, and the T273A mutant only partially blocked maturation. Our results show that JAM-A is essential for the development of polarity in cultured hepatic cells via its possible phosphorylation and recruitment of relevant PDZ proteins and that hepatic polarity is achieved within a narrow range of JAM-A expression levels. Importantly, formation/maintenance of TJs and the apical domain in hepatic cells are linked, unlike simple epithelia.

  17. Comparison of clinical grade type 1 polarized and standard matured dendritic cells for cancer immunotherapy

    DEFF Research Database (Denmark)

    Hansen, Morten; Hjortø, Gertrud Malene; Donia, Marco


    Monocyte-derived dendritic cells (DCs) used for immunotherapy e.g. against cancer are commonly matured by pro-inflammatory cytokines (TNF-α, IL-1β, IL-6) and prostaglandin E2 although the absence of Toll-like receptor mediated activation prevents secretion of IL-12 from DCs and subsequent efficient......DCs and strikingly had the highest expression of the inhibitory molecules PD-L1 and CD25. Thus, further studies with type 1 polarized DCs are warranted for use in immunotherapy, but when combined with PGE2 as in mpDCs, they seems to be less optimal for maturation of DCs....

  18. Cloning and expression of Xenopus Prickle, an orthologue of a Drosophila planar cell polarity gene. (United States)

    Wallingford, John B; Goto, Toshiyasu; Keller, Ray; Harland, Richard M


    We have cloned Xenopus orthologues of the Drosophila planar cell polarity (PCP) gene Prickle. Xenopus Prickle (XPk) is expressed in tissues at the dorsal midline during gastrulation and early neurulation. XPk is later expressed in a segmental pattern in the presomitic mesoderm and then in recently formed somites. XPk is also expressed in the tailbud, pronephric duct, retina, and the otic vesicle. The complex expression pattern of XPk suggests that PCP signaling is used in a diverse array of developmental processes in vertebrate embryos.

  19. An instructive role for C. elegans E-cadherin in translating cell contact cues into cortical polarity. (United States)

    Klompstra, Diana; Anderson, Dorian C; Yeh, Justin Y; Zilberman, Yuliya; Nance, Jeremy


    Cell contacts provide spatial cues that polarize early embryos and epithelial cells. The homophilic adhesion protein E-cadherin is required for contact-induced polarity in many cells. However, it is debated whether E-cadherin functions instructively as a spatial cue, or permissively by ensuring adequate adhesion so that cells can sense other contact signals. In Caenorhabditis elegans, contacts polarize early embryonic cells by recruiting the RhoGAP PAC-1 to the adjacent cortex, inducing PAR protein asymmetry. Here we show that the E-cadherin HMR-1, which is dispensable for adhesion, functions together with the α-catenin HMP-1, the p120 catenin JAC-1, and the previously uncharacterized linker PICC-1 (human CCDC85A-C) to bind PAC-1 and recruit it to contacts. Mislocalizing the HMR-1 intracellular domain to contact-free surfaces draws PAC-1 to these sites and depolarizes cells, demonstrating an instructive role for HMR-1 in polarization. Our findings identify an E-cadherin-mediated pathway that translates cell contacts into cortical polarity by directly recruiting a symmetry-breaking factor to the adjacent cortex.

  20. Ciliogenesis defects in embryos lacking inturned or fuzzy function are associated with failure of planar cell polarity and Hedgehog signaling. (United States)

    Park, Tae Joo; Haigo, Saori L; Wallingford, John B


    The vertebrate planar cell polarity (PCP) pathway has previously been found to control polarized cell behaviors rather than cell fate. We report here that disruption of Xenopus laevis orthologs of the Drosophila melanogaster PCP effectors inturned (in) or fuzzy (fy) affected not only PCP-dependent convergent extension but also elicited embryonic phenotypes consistent with defective Hedgehog signaling. These defects in Hedgehog signaling resulted from a broad requirement for Inturned and Fuzzy in ciliogenesis. We show that these proteins govern apical actin assembly and thus control the orientation, but not assembly, of ciliary microtubules. Finally, accumulation of Dishevelled and Inturned near the basal apparatus of cilia suggests that these proteins function in a common pathway with core PCP components to regulate ciliogenesis. Together, these data highlight the interrelationships between cell polarity, cellular morphogenesis, signal transduction and cell fate specification.

  1. Cell and tissue polarity in the intestinal tract during tumourigenesis: cells still know the right way up, but tissue organization is lost. (United States)

    Fatehullah, Aliya; Appleton, Paul L; Näthke, Inke S


    Cell and tissue polarity are tightly coupled and are vital for normal tissue homeostasis. Changes in cellular and tissue organization are common to even early stages of disease, particularly cancer. The digestive tract is the site of the second most common cause of cancer deaths in the developed world. Tumours in this tissue arise in an epithelium that has a number of axes of cell and tissue polarity. Changes in cell and tissue polarity in response to genetic changes that are known to underpin disease progression provide clues about the link between molecular-, cellular- and tissue-based mechanisms that accompany cancer. Mutations in adenomatous polyposis coli (APC) are common to most colorectal cancers in humans and are sufficient to cause tumours in mouse intestine. Tissue organoids mimic many features of whole tissue and permit identifying changes at different times after inactivation of APC. Using gut organoids, we show that tissue polarity is lost very early during cancer progression, whereas cell polarity, at least apical-basal polarity, is maintained and changes only at later stages. These observations reflect the situation in tumours and validate tissue organoids as a useful system to investigate the relationship between cell polarity and tissue organization.

  2. Wnt-signaling and planar cell polarity genes regulate axon guidance along the anteroposterior axis in C. elegans. (United States)

    Ackley, Brian D


    During the development of the nervous system, neurons encounter signals that inform their outgrowth and polarization. Understanding how these signals combinatorially function to pattern the nervous system is of considerable interest to developmental neurobiologists. The Wnt ligands and their receptors have been well characterized in polarizing cells during asymmetric cell division. The planar cell polarity (PCP) pathway is also critical for cell polarization in the plane of an epithelium. The core set of PCP genes include members of the conserved Wnt-signaling pathway, such as Frizzled and Disheveled, but also the cadherin-domain protein Flamingo. In Drosophila, the Fat and Dachsous cadherins also function in PCP, but in parallel to the core PCP components. C. elegans also have two Fat-like and one Dachsous-like cadherins, at least one of which, cdh-4, contributes to neural development. In C. elegans Wnt ligands and the conserved PCP genes have been shown to regulate a number of different events, including embryonic cell polarity, vulval morphogenesis, and cell migration. As is also observed in vertebrates, the Wnt and PCP genes appear to function to primarily provide information about the anterior to posterior axis of development. Here, we review the recent work describing how mutations in the Wnt and core PCP genes affect axon guidance and synaptogenesis in C. elegans.

  3. Prickle1 mutation causes planar cell polarity and directional cell migration defects associated with cardiac outflow tract anomalies and other structural birth defects

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    Brian C. Gibbs


    Full Text Available Planar cell polarity (PCP is controlled by a conserved pathway that regulates directional cell behavior. Here, we show that mutant mice harboring a newly described mutation termed Beetlejuice (Bj in Prickle1 (Pk1, a PCP component, exhibit developmental phenotypes involving cell polarity defects, including skeletal, cochlear and congenital cardiac anomalies. Bj mutants die neonatally with cardiac outflow tract (OFT malalignment. This is associated with OFT shortening due to loss of polarized cell orientation and failure of second heart field cell intercalation mediating OFT lengthening. OFT myocardialization was disrupted with cardiomyocytes failing to align with the direction of cell invasion into the outflow cushions. The expression of genes mediating Wnt signaling was altered. Also noted were shortened but widened bile ducts and disruption in canonical Wnt signaling. Using an in vitro wound closure assay, we showed Bj mutant fibroblasts cannot establish polarized cell morphology or engage in directional cell migration, and their actin cytoskeleton failed to align with the direction of wound closure. Unexpectedly, Pk1 mutants exhibited primary and motile cilia defects. Given Bj mutant phenotypes are reminiscent of ciliopathies, these findings suggest Pk1 may also regulate ciliogenesis. Together these findings show Pk1 plays an essential role in regulating cell polarity and directional cell migration during development.

  4. Prickle1 mutation causes planar cell polarity and directional cell migration defects associated with cardiac outflow tract anomalies and other structural birth defects. (United States)

    Gibbs, Brian C; Damerla, Rama Rao; Vladar, Eszter K; Chatterjee, Bishwanath; Wan, Yong; Liu, Xiaoqin; Cui, Cheng; Gabriel, George C; Zahid, Maliha; Yagi, Hisato; Szabo-Rogers, Heather L; Suyama, Kaye L; Axelrod, Jeffrey D; Lo, Cecilia W


    Planar cell polarity (PCP) is controlled by a conserved pathway that regulates directional cell behavior. Here, we show that mutant mice harboring a newly described mutation termed Beetlejuice (Bj) in Prickle1 (Pk1), a PCP component, exhibit developmental phenotypes involving cell polarity defects, including skeletal, cochlear and congenital cardiac anomalies. Bj mutants die neonatally with cardiac outflow tract (OFT) malalignment. This is associated with OFT shortening due to loss of polarized cell orientation and failure of second heart field cell intercalation mediating OFT lengthening. OFT myocardialization was disrupted with cardiomyocytes failing to align with the direction of cell invasion into the outflow cushions. The expression of genes mediating Wnt signaling was altered. Also noted were shortened but widened bile ducts and disruption in canonical Wnt signaling. Using an in vitro wound closure assay, we showed Bj mutant fibroblasts cannot establish polarized cell morphology or engage in directional cell migration, and their actin cytoskeleton failed to align with the direction of wound closure. Unexpectedly, Pk1 mutants exhibited primary and motile cilia defects. Given Bj mutant phenotypes are reminiscent of ciliopathies, these findings suggest Pk1 may also regulate ciliogenesis. Together these findings show Pk1 plays an essential role in regulating cell polarity and directional cell migration during development.

  5. Infection of Polarized MDCK Cells with Herpes Simplex Virus 1: Two Asymmetrically Distributed Cell Receptors Interact with Different Viral Proteins (United States)

    Sears, Amy E.; McGwire, Bradford S.; Roizman, Bernard


    Herpes simplex virus 1 attaches to at least two cell surface receptors. In polarized epithelial (Madin-Darby canine kidney; MDCK) cells one receptor is located in the apical surface and attachment to the cells requires the presence of glycoprotein C in the virus. The second receptor is located in the basal surface and does not require the presence of glycoprotein C. Exposure of MDCK cells at either the apical or basal surface to wild-type virus yields plaques and viral products whereas infection by a glycoprotein C-negative mutant yields identical results only after exposure of MDCK cells to virus at the basal surface. Multiple receptors for viral entry into cells expand the host range of the virus. The observation that glycoprotein C-negative mutants are infectious in many nonpolarized cell lines suggests that cells in culture may express more than one receptor and explains why genes that specify the viral proteins that recognize redundant receptors, like glycoprotein C, are expendable.

  6. The abdomen of Drosophila: does planar cell polarity orient the neurons of mechanosensory bristles?

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    Fabre Caroline CG


    Full Text Available Abstract Background In the adult abdomen of Drosophila, the shafts of mechanosensory bristles point consistently from anterior to posterior. This is an example of planar cell polarity (PCP; some genes responsible for PCP have been identified. Each adult bristle is made by a clone of four cells, including the neuron that innervates it, but little is known as to how far the formation or positions of these cells depends on PCP. The neurons include a single dendrite and an axon; it is not known whether the orientation of these processes is influenced by PCP. Results We describe the development of the abdominal mechanosensory bristles in detail. The division of the precursor cell gives two daughters, one (pIIa divides to give rise to the bristle shaft and socket cell and the other (pIIb generates the neuron, the sheath and the fifth cell. Although the bristles and their associated shaft and socket cells are consistently oriented, the positioning and behaviour of the neuron, the sheath and the fifth cell, as well as the orientation of the axons and the dendritic paths, depend on location. For example, in the anterior zone of the segment, the axons grow posteriorly, while in the posterior zone, they grow anteriorly. Manipulating the PCP genes can reverse bristle orientation, change the path taken by the dendrite and the position of the cell body of the neuron. However, the paths taken by the axon are not affected. Conclusion PCP genes, such as starry night and dachsous orient the bristles and position the neuronal cell body and affect the shape of the dendrites. However, these PCP genes do not appear to change the paths followed by the sensory axons, which must, therefore, be polarised by other factors.

  7. Normal and tumor-derived myoepithelial cells differ in their ability to interact with luminal breast epithelial cells for polarity and basement membrane deposition

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    Gudjonsson, Thorarinn; Ronnov-Jessen, Lone; Villadsen, Rene; Rank, Fritz; Bissell, Mina J.; Petersen, Ole William


    The signals that determine the correct polarity of breast epithelial structures in vivo are not understood. We have shown previously that luminal epithelial cells can be polarized when cultured within a reconstituted basement membrane gel. We reasoned that such cues in vivo may be given by myoepithelial cells. Accordingly, we used an assay where luminal epithelial cells are incorrectly polarized to test this hypothesis. We show that culturing human primary luminal epithelial cells within collagen-I gels leads to formation of structures with no lumina and with reverse polarity as judged by dual stainings for sialomucin, epithelial specific antigen or occludin. No basement membrane is deposited, and {beta}4-integrin staining is negative. Addition of purified human myoepithelial cells isolated from normal glands corrects the inverse polarity, and leads to formation of double-layered acini with central lumina. Among the laminins present in the human breast basement membrane (laminin-1, -5 and -10/11), laminin-1 was unique in its ability to substitute for myoepithelial cells in polarity reversal. Myoepithelial cells were purified also from four different breast cancer sources including a biphasic cell line. Three out of four samples either totally lacked the ability to interact with luminal epithelial cells, or conveyed only correction of polarity in a fraction of acini. This behavior was directly related to the ability of the tumor myoepithelial cells to produce {alpha}-1 chain of laminin. In vivo, breast carcinomas were either negative for laminin-1 (7/12 biopsies) or showed a focal, fragmented deposition of a less intensely stained basement membrane (5/12 biopsies). Dual staining with myoepithelial markers revealed that tumorassociated myoepithelial cells were either negative or weakly positive for expression of laminin-1, establishing a strong correlation between loss of laminin-1 and breast cancer. We conclude that the double-layered breast acinus may be

  8. Treg/Th17 polarization by distinct subsets of breast cancer cells is dictated by the interaction with mesenchymal stem cells


    Patel, Shyam A.; Dave, Meneka A.; Bliss, Sarah A.; Giec-Ujda, Agata B.; Bryan, Margarette; Pliner, Lillian F.; Rameshwar, Pranela


    Breast cancer (BC) cells (BCCs) exist within a hierarchy beginning with cancer stem cells (CSCs). Unsorted BCCs interact with mesenchymal stem cells (MSCs) to induce regulatory T cells (Tregs). This study investigated how distinct BCC subsets interacted with MSCs to polarize T-cell response, Tregs versus T helper 17 (Th17). This study tested BC initiating cells (CSCs) and the relatively more mature early and late BC progenitors. CSCs interacted with the highest avidity to MSCs. This interacti...

  9. Control of vertebrate core planar cell polarity protein localization and dynamics by Prickle 2. (United States)

    Butler, Mitchell T; Wallingford, John B


    Planar cell polarity (PCP) is a ubiquitous property of animal tissues and is essential for morphogenesis and homeostasis. In most cases, this fundamental property is governed by a deeply conserved set of 'core PCP' proteins, which includes the transmembrane proteins Van Gogh-like (Vangl) and Frizzled (Fzd), as well as the cytoplasmic effectors Prickle (Pk) and Dishevelled (Dvl). Asymmetric localization of these proteins is thought to be central to their function, and understanding the dynamics of these proteins is an important challenge in developmental biology. Among the processes that are organized by the core PCP proteins is the directional beating of cilia, such as those in the vertebrate node, airway and brain. Here, we exploit the live imaging capabilities of Xenopus to chart the progressive asymmetric localization of fluorescent reporters of Dvl1, Pk2 and Vangl1 in a planar polarized ciliated epithelium. Using this system, we also characterize the influence of Pk2 on the asymmetric dynamics of Vangl1 at the cell cortex, and we define regions of Pk2 that control its own localization and those impacting Vangl1. Finally, our data reveal a striking uncoupling of Vangl1 and Dvl1 asymmetry. This study advances our understanding of conserved PCP protein functions and also establishes a rapid, tractable platform to facilitate future in vivo studies of vertebrate PCP protein dynamics.

  10. TNF-α decreases VEGF secretion in highly polarized RPE cells but increases it in non-polarized RPE cells related to crosstalk between JNK and NF-κB pathways.

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    Hiroto Terasaki

    Full Text Available Asymmetrical secretion of vascular endothelial growth factor (VEGF by retinal pigment epithelial (RPE cells in situ is critical for maintaining the homeostasis of the retina and choroid. VEGF is also involved in the development and progression of age-related macular degeneration (AMD. We studied the effect of tumor necrosis factor-α (TNF-α on the secretion of VEGF in polarized and non-polarized RPE cells (P-RPE cells and N-RPE cells, respectively in culture and in situ in rats. A subretinal injection of TNF-α caused a decrease in VEGF expression and choroidal atrophy. Porcine RPE cells were seeded on Transwell™ filters, and their maturation and polarization were confirmed by the asymmetrical VEGF secretion and trans electrical resistance. Exposure to TNF-α decreased the VEGF secretion in P-RPE cells but increased it in N-RPE cells in culture. TNF-α inactivated JNK in P-RPE cells but activated it in N-RPE cells, and TNF-α activated NF-κB in P-RPE cells but not in N-RPE cells. Inhibition of NF-κB activated JNK in both types of RPE cells indicating crosstalk between JNK and NF-κB. TNF-α induced the inhibitory effects of NF-κB on JNK in P-RPE cells because NF-κB is continuously inactivated. In N-RPE cells, however, it was not evident because NF-κB was already activated. The basic activation pattern of JNK and NF-κB and their crosstalk led to opposing responses of RPE cells to TNF-α. These results suggest that VEGF secretion under inflammatory conditions depends on cellular polarization, and the TNF-α-induced VEGF down-regulation may result in choroidal atrophy in polarized physiological RPE cells. TNF-α-induced VEGF up-regulation may cause neovascularization by non-polarized or non-physiological RPE cells.

  11. Two separate molecular systems, Dachsous/Fat and Starry night/Frizzled, act independently to confer planar cell polarity. (United States)

    Casal, José; Lawrence, Peter A; Struhl, Gary


    Planar polarity is a fundamental property of epithelia in animals and plants. In Drosophila it depends on at least two sets of genes: one set, the Ds system, encodes the cadherins Dachsous (Ds) and Fat (Ft), as well as the Golgi protein Four-jointed. The other set, the Stan system, encodes Starry night (Stan or Flamingo) and Frizzled. The prevailing view is that the Ds system acts via the Stan system to orient cells. However, using the Drosophila abdomen, we find instead that the two systems operate independently: each confers and propagates polarity, and can do so in the absence of the other. We ask how the Ds system acts; we find that either Ds or Ft is required in cells that send information and we show that both Ds and Ft are required in the responding cells. We consider how polarity may be propagated by Ds-Ft heterodimers acting as bridges between cells.

  12. 10.6% Certified Colloidal Quantum Dot Solar Cells via Solvent-Polarity-Engineered Halide Passivation. (United States)

    Lan, Xinzheng; Voznyy, Oleksandr; García de Arquer, F Pelayo; Liu, Mengxia; Xu, Jixian; Proppe, Andrew H; Walters, Grant; Fan, Fengjia; Tan, Hairen; Liu, Min; Yang, Zhenyu; Hoogland, Sjoerd; Sargent, Edward H


    Colloidal quantum dot (CQD) solar cells are solution-processed photovoltaics with broad spectral absorption tunability. Major advances in their efficiency have been made via improved CQD surface passivation and device architectures with enhanced charge carrier collection. Herein, we demonstrate a new strategy to improve further the passivation of CQDs starting from the solution phase. A cosolvent system is employed to tune the solvent polarity in order to achieve the solvation of methylammonium iodide (MAI) and the dispersion of hydrophobic PbS CQDs simultaneously in a homogeneous phase, otherwise not achieved in a single solvent. This process enables MAI to access the CQDs to confer improved passivation. This, in turn, allows for efficient charge extraction from a thicker photoactive layer device, leading to a certified solar cell power conversion efficiency of 10.6%, a new certified record in CQD photovoltaics.

  13. Wnt-Frizzled/planar cell polarity signaling: cellular orientation by facing the wind (Wnt). (United States)

    Yang, Yingzi; Mlodzik, Marek


    The establishment of planar cell polarity (PCP) in epithelial and mesenchymal cells is a critical, evolutionarily conserved process during development and organogenesis. Analyses in Drosophila and several vertebrate model organisms have contributed a wealth of information on the regulation of PCP. A key conserved pathway regulating PCP, the so-called core Wnt-Frizzled PCP (Fz/PCP) signaling pathway, was initially identified through genetic studies of Drosophila. PCP studies in vertebrates, most notably mouse and zebrafish, have identified novel factors in PCP signaling and have also defined cellular features requiring PCP signaling input. These studies have shifted focus to the role of Van Gogh (Vang)/Vangl genes in this molecular system. This review focuses on new insights into the core Fz/Vangl/PCP pathway and recent advances in Drosophila and vertebrate PCP studies. We attempt to integrate these within the existing core Fz/Vangl/PCP signaling framework.

  14. Tissue/planar cell polarity in vertebrates: new insights and new questions. (United States)

    Wang, Yanshu; Nathans, Jeremy


    This review focuses on the tissue/planar cell polarity (PCP) pathway and its role in generating spatial patterns in vertebrates. Current evidence suggests that PCP integrates both global and local signals to orient diverse structures with respect to the body axes. Interestingly, the system acts on both subcellular structures, such as hair bundles in auditory and vestibular sensory neurons, and multicellular structures, such as hair follicles. Recent work has shown that intriguing connections exist between the PCP-based orienting system and left-right asymmetry, as well as between the oriented cell movements required for neural tube closure and tubulogenesis. Studies in mice, frogs and zebrafish have revealed that similarities, as well as differences, exist between PCP in Drosophila and vertebrates.

  15. Planar cell polarity effector gene Intu regulates cell fate-specific differentiation of keratinocytes through the primary cilia. (United States)

    Dai, D; Li, L; Huebner, A; Zeng, H; Guevara, E; Claypool, D J; Liu, A; Chen, J


    Genes involved in the planar cell polarity (PCP) signaling pathway are essential for a number of developmental processes in mammals, such as convergent extension and ciliogenesis. Tissue-specific PCP effector genes of the PCP signaling pathway are believed to mediate PCP signals in a tissue- and cell type-specific manner. However, how PCP signaling controls the morphogenesis of mammalian tissues remains unclear. In this study, we investigated the role of inturned (Intu), a tissue-specific PCP effector gene, during hair follicle formation in mice. Tissue-specific disruption of Intu in embryonic epidermis resulted in hair follicle morphogenesis arrest because of the failure of follicular keratinocyte to differentiate. Targeting Intu in the epidermis resulted in almost complete loss of primary cilia in epidermal and follicular keratinocytes, and a suppressed hedgehog signaling pathway. Surprisingly, the epidermal stratification and differentiation programs and barrier function were not affected. These results demonstrate that tissue-specific PCP effector genes of the PCP signaling pathway control the differentiation of keratinocytes through the primary cilia in a cell fate- and context-dependent manner, which may be critical in orchestrating the propagation and interpretation of polarity signals established by the core PCP components.

  16. The Wnt coreceptor Ryk regulates Wnt/planar cell polarity by modulating the degradation of the core planar cell polarity component Vangl2. (United States)

    Andre, Philipp; Wang, Qianyi; Wang, Na; Gao, Bo; Schilit, Arielle; Halford, Michael M; Stacker, Steven A; Zhang, Xuemin; Yang, Yingzi


    The Wnt signaling pathways control many critical developmental and adult physiological processes. In vertebrates, one fundamentally important function of Wnts is to provide directional information by regulating the evolutionarily conserved planar cell polarity (PCP) pathway during embryonic morphogenesis. However, despite the critical roles of Wnts and PCP in vertebrate development and disease, little is known about the molecular mechanisms underlying Wnt regulation of PCP. Here, we have found that the receptor-like tyrosine kinase (Ryk), a Wnt5a-binding protein required in axon guidance, regulates PCP signaling. We show that Ryk interacts with Vangl2 genetically and biochemically, and such interaction is potentiated by Wnt5a. Loss of Ryk in a Vangl2(+/-) background results in classic PCP defects, including open neural tube, misalignment of sensory hair cells in the inner ear, and shortened long bones in the limbs. Complete loss of both Ryk and Vangl2 results in more severe phenotypes that resemble the Wnt5a(-/-) mutant in many aspects such as shortened anterior-posterior body axis, limb, and frontonasal process. Our data identify the Wnt5a-binding protein Ryk as a general regulator of the mammalian Wnt/PCP signaling pathway. We show that Ryk transduces Wnt5a signaling by forming a complex with Vangl2 and that Ryk regulates PCP by at least in part promoting Vangl2 stability. As human mutations in WNT5A and VANGL2 are found to cause Robinow syndrome and neural tube defects, respectively, our results further suggest that human mutations in RYK may also be involved in these diseases.

  17. Planar Cell Polarity Effector Fritz Interacts with Dishevelled and Has Multiple Functions in Regulating PCP (United States)

    Wang, Ying; Naturale, Victor F.; Adler, Paul N.


    The Planar cell Polarity Effector (PPE) genes inturned, fuzzy, and fritz are downstream components in the frizzled/starry night signaling pathway, and their function is instructed by upstream Planar Cell Polarity (PCP) core genes such as frizzled and dishevelled. PPE proteins accumulate asymmetrically in wing cells and function in a protein complex mediated by direct interactions between In and Frtz and In and Fy. How the PCP proteins instruct the accumulation of PPE protein is unknown. We found a likely direct interaction between Dishevelled and Fritz and Dishevelled and Fuzzy that could play a role in this. We previously found that mild overexpression of frtz rescued a weak in allele. To determine if this was due to extra Frtz stabilizing mutant In or due to Frtz being able to bypass the need for In we generate a precise deletion of the inturned gene (inPD). We found that mild overexpression of Fritz partially rescued inPD, indicating that fritz has In independent activity in PCP. Previous studies of PPE proteins used fixed tissues, and did not provide any insights into the dynamic properties of PPE proteins. We used CRISPR/Cas9 genome editing technology to edit the fritz gene to add a green fluorescent protein tag. fritzmNeonGreen provides complete rescue activity and works well for in vivo imaging. Our data showed that Fritz is very dynamic in epidermal cells and preferentially distributed to discrete membrane subdomains (“puncta”). Surprisingly, we found it in stripes in developing bristles. PMID:28258110

  18. MHV-A59 enters polarized murine epithelial cells through the apical surface but is released basolaterally

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    Rossen, J W; Voorhout, W F; Horzinek, M C; van der Ende, A; Strous, G J; Rottier, P J


    Coronaviruses have a marked tropism for epithelial cells. Entry and release of the porcine transmissible gastroenteritis virus (TGEV) is restricted to apical surfaces of polarized epithelial cells, as we have recently shown (J. W. A. Rossen, C. P. J. Bekker, W. F. Voorhout, G. J. A. M. Strous, A. va

  19. The Light-Induced Field-Effect Solar Cell Concept - Perovskite Nanoparticle Coating Introduces Polarization Enhancing Silicon Cell Efficiency. (United States)

    Wang, Yusheng; Xia, Zhouhui; Liu, Lijia; Xu, Weidong; Yuan, Zhongcheng; Zhang, Yupeng; Sirringhaus, Henning; Lifshitz, Yeshayahu; Lee, Shui-Tong; Bao, Qiaoliang; Sun, Baoquan


    Solar cell generates electrical energy from light one via pulling excited carrier away under built-in asymmetry. Doped semiconductor with antireflection layer is general strategy to achieve this including crystalline silicon (c-Si) solar cell. However, loss of extra energy beyond band gap and light reflection in particular wavelength range is known to hinder the efficiency of c-Si cell. Here, it is found that part of short wavelength sunlight can be converted into polarization electrical field, which strengthens asymmetry in organic-c-Si heterojunction solar cell through molecule alignment process. The light harvested by organometal trihalide perovskite nanoparticles (NPs) induces molecular alignment on a conducting polymer, which generates positive electrical surface field. Furthermore, a "field-effect solar cell" is successfully developed and implemented by combining perovskite NPs with organic/c-Si heterojunction associating with light-induced molecule alignment, which achieves an efficiency of 14.3%. In comparison, the device with the analogous structure without perovskite NPs only exhibits an efficiency of 12.7%. This finding provides a novel concept to design solar cell by sacrificing part of sunlight to provide "extra" asymmetrical field continuously as to drive photogenerated carrier toward respective contacts under direct sunlight. Moreover, it also points out a method to combine promising perovskite material with c-Si solar cell.

  20. Planar cell polarity in the Drosophila eye is directed by graded Four-jointed and Dachsous expression. (United States)

    Simon, Michael A


    Planar cell polarity (PCP) occurs when the cells of an epithelium are polarized along a common axis lying in the epithelial plane. During the development of PCP, cells respond to long-range directional signals that specify the axis of polarization. In previous work on the Drosophila eye, we proposed that a crucial step in this process is the establishment of graded expression of the cadherin Dachsous (Ds) and the Golgi-associated protein Four-jointed (Fj). These gradients were proposed to specify the direction of polarization by producing an activity gradient of the cadherin Fat within each ommatidium. In this report, I test and confirm the key predictions of this model by altering the patterns of Fj, Ds and Fat expression. It is shown that the gradients of Fj and Ds expression provide partially redundant positional information essential for specifying the polarization axis. I further demonstrate that reversing the Fj and Ds gradients can lead to reversal of the axis of polarization. Finally, it is shown that an ectopic gradient of Fat expression can re-orient PCP in the eye. In contrast to the eye, the endogenous gradients of Fj and Ds expression do not play a major role in directing PCP in the wing. Thus, this study reveals that the two tissues use different strategies to orient their PCP.

  1. Activation of the Wnt/planar cell polarity pathway is required for pericyte recruitment during pulmonary angiogenesis. (United States)

    Yuan, Ke; Orcholski, Mark E; Panaroni, Cristina; Shuffle, Eric M; Huang, Ngan F; Jiang, Xinguo; Tian, Wen; Vladar, Eszter K; Wang, Lingli; Nicolls, Mark R; Wu, Joy Y; de Jesus Perez, Vinicio A


    Pericytes are perivascular cells localized to capillaries that promote vessel maturation, and their absence can contribute to vessel loss. Whether impaired endothelial-pericyte interaction contributes to small vessel loss in pulmonary arterial hypertension (PAH) is unclear. Using 3G5-specific, immunoglobulin G-coated magnetic beads, we isolated pericytes from the lungs of healthy subjects and PAH patients, followed by lineage validation. PAH pericytes seeded with healthy pulmonary microvascular endothelial cells failed to associate with endothelial tubes, resulting in smaller vascular networks compared to those with healthy pericytes. After the demonstration of abnormal polarization toward endothelium via live-imaging and wound-healing studies, we screened PAH pericytes for abnormalities in the Wnt/planar cell polarity (PCP) pathway, which has been shown to regulate cell motility and polarity in the pulmonary vasculature. PAH pericytes had reduced expression of frizzled 7 (Fzd7) and cdc42, genes crucial for Wnt/PCP activation. With simultaneous knockdown of Fzd7 and cdc42 in healthy pericytes in vitro and in a murine model of angiogenesis, motility and polarization toward pulmonary microvascular endothelial cells were reduced, whereas with restoration of both genes in PAH pericytes, endothelial-pericyte association was improved, with larger vascular networks. These studies suggest that the motility and polarity of pericytes during pulmonary angiogenesis are regulated by Wnt/PCP activation, which can be targeted to prevent vessel loss in PAH.

  2. Bonzo/CXCR6 expression defines type 1–polarized T-cell subsets with extralymphoid tissue homing potential



    Chemokine receptor expression is finely controlled during T-cell development. We show that newly identified chemokine receptor Bonzo/CXCR6 is expressed by subsets of Th1 or T-cytotoxic 1 (Tc1) cells, but not by Th2 or Tc2 cells, establishing Bonzo as a differential marker of polarized type 1 T cells in vitro and in vivo. Priming of naive T cells by dendritic cells induces expression of Bonzo on T cells. IL-12 enhances this dendritic cell–dependent upregulation, while IL-4 inhibits it. In bloo...

  3. Planar cell polarity aligns osteoblast division in response to substrate strain. (United States)

    Galea, Gabriel L; Meakin, Lee B; Savery, Dawn; Taipaleenmaki, Hanna; Delisser, Peter; Stein, Gary S; Copp, Andrew J; van Wijnen, Andre J; Lanyon, Lance E; Price, Joanna S


    Exposure of bone to dynamic strain increases the rate of division of osteoblasts and also influences the directional organization of the cellular and molecular structure of the bone tissue that they produce. Here, we report that brief exposure to dynamic substrate strain (sufficient to rapidly stimulate cell division) influences the orientation of osteoblastic cell division. The initial proliferative response to strain involves canonical Wnt signaling and can be blocked by sclerostin. However, the strain-related orientation of cell division is independently influenced through the noncanonical Wnt/planar cell polarity (PCP) pathway. Blockade of Rho-associated coiled kinase (ROCK), a component of the PCP pathway, prevents strain-related orientation of division in osteoblast-like Saos-2 cells. Heterozygous loop-tail mutation of the core PCP component van Gogh-like 2 (Vangl2) in mouse osteoblasts impairs the orientation of division in response to strain. Examination of bones from Vangl2 loop-tail heterozygous mice by µCT and scanning electron microscopy reveals altered bone architecture and disorganized bone-forming surfaces. Hence, in addition to the well-accepted role of PCP involvement in response to developmental cues during skeletal morphogenesis, our data reveal that this pathway also acts postnatally, in parallel with canonical Wnt signaling, to transduce biomechanical cues into skeletal adaptive responses. The simultaneous and independent actions of these two pathways appear to influence both the rate and orientation of osteoblast division, thus fine-tuning bone architecture to meet the structural demands of functional loading.

  4. Structural polarity and dynamics of male germline stem cells in an insect (milkweed bug Oncopeltus fasciatus). (United States)

    Dorn, David C; Dorn, August


    Knowing the structure opens a door for a better understanding of function because there is no function without structure. Male germline stem cells (GSCs) of the milkweed bug (Oncopeltus fasciatus) exhibit a very extraordinary structure and a very special relationship with their niche, the apical cells. This structural relationship is strikingly different from that known in the fruit fly (Drosophila melanogaster) -- the most successful model system, which allowed deep insights into the signaling interactions between GSCs and niche. The complex structural polarity of male GSCs in the milkweed bug combined with their astonishing dynamics suggest that cell morphology and dynamics are causally related with the most important regulatory processes that take place between GSCs and niche and ensure maintenance, proliferation, and differentiation of GSCs in accordance with the temporal need of mature sperm. The intricate structure of the GSCs of the milkweed bug (and probably of some other insects, i.e., moths) is only accessible by electron microscopy. But, studying singular sections through the apical complex (i.e., GSCs and apical cells) is not sufficient to obtain a full picture of the GSCs; especially, the segregation of projection terminals is not tangible. Only serial sections and their overlay can establish whether membrane ingrowths merely constrict projections or whether a projection terminal is completely cut off. To sequence the GSC dynamics, it is necessary to include juvenile stages, when the processes start and the GSCs occur in small numbers. The fine structural analysis of segregating projection terminals suggests that these terminals undergo autophagocytosis. Autophagosomes can be labeled by markers. We demonstrated acid phosphatase and thiamine pyrophosphatase (TPPase). Both together are thought to identify autophagosomes. Using the appropriate substrate of the enzymes and cerium chloride, the precipitation of electron-dense cerium phosphate granules

  5. Planar cell polarity proteins differentially regulate extracellular matrix organization and assembly during zebrafish gastrulation. (United States)

    Dohn, Michael R; Mundell, Nathan A; Sawyer, Leah M; Dunlap, Julie A; Jessen, Jason R


    Zebrafish gastrulation cell movements occur in the context of dynamic changes in extracellular matrix (ECM) organization and require the concerted action of planar cell polarity (PCP) proteins that regulate cell elongation and mediolateral alignment. Data obtained using Xenopus laevis gastrulae have shown that integrin-fibronectin interactions underlie the formation of polarized cell protrusions necessary for PCP and have implicated PCP proteins themselves as regulators of ECM. By contrast, the relationship between establishment of PCP and ECM assembly/remodeling during zebrafish gastrulation is unclear. We previously showed that zebrafish embryos carrying a null mutation in the four-pass transmembrane PCP protein vang-like 2 (vangl2) exhibit increased matrix metalloproteinase activity and decreased immunolabeling of fibronectin. These data implicated for the first time a core PCP protein in the regulation of pericellular proteolysis of ECM substrates and raised the question of whether other zebrafish PCP proteins also impact ECM organization. In Drosophila melanogaster, the cytoplasmic PCP protein Prickle binds Van Gogh and regulates its function. Here we report that similar to vangl2, loss of zebrafish prickle1a decreases fibronectin protein levels in gastrula embryos. We further show that Prickle1a physically binds Vangl2 and regulates both the subcellular distribution and total protein level of Vangl2. These data suggest that the ability of Prickle1a to impact fibronectin organization is at least partly due to effects on Vangl2. In contrast to loss of either Vangl2 or Prickle1a function, we find that glypican4 (a Wnt co-receptor) and frizzled7 mutant gastrula embryos with disrupted non-canonical Wnt signaling exhibit the opposite phenotype, namely increased fibronectin assembly. Our data show that glypican4 mutants do not have decreased proteolysis of ECM substrates, but instead have increased cell surface cadherin protein expression and increased intercellular

  6. Disruption of planar cell polarity signaling results in congenital heart defects and cardiomyopathy attributable to early cardiomyocyte disorganization. (United States)

    Phillips, Helen M; Rhee, Hong Jun; Murdoch, Jennifer N; Hildreth, Victoria; Peat, Jonathan D; Anderson, Robert H; Copp, Andrew J; Chaudhry, Bill; Henderson, Deborah J


    The Drosophila scribble gene regulates apical-basal polarity and is implicated in control of cellular architecture and cell growth control. Mutations in mammalian Scrib (circletail; Crc mutant) also result in abnormalities suggestive of roles in planar cell polarity regulation. We show that Crc mutants develop heart malformations and cardiomyopathy attributable to abnormalities in cardiomyocyte organization within the early heart tube. N-Cadherin is lost from the cardiomyocyte cell membrane and cell-cell adhesion is disrupted. This results in abnormalities in heart looping and formation of both the trabeculae and compact myocardium, which ultimately results in cardiac misalignment defects and ventricular noncompaction. Thus, these late abnormalities arise from defects occurring at the earliest stages of heart development. Mislocalization of Vangl2 in Crc/Crc cardiomyocytes suggests Scrib is acting in the planar cell polarity pathway in this tissue. Moreover, double heterozygosity for mutations in both Scrib and Vangl2 can cause cardiac defects similar to those found in homozygous mutants for each gene but without other major defects. We propose that heterozygosity for mutations in different genes in the planar cell polarity pathway may be an important mechanism for congenital heart defects and cardiomyopathy in humans.

  7. DNA replication defects delay cell division and disrupt cell polarity in early Caenorhabditis elegans embryos. (United States)

    Encalada, S E; Martin, P R; Phillips, J B; Lyczak, R; Hamill, D R; Swan, K A; Bowerman, B


    In early Caenorhabditis elegans embryos, asymmetric cell divisions produce descendants with asynchronous cell cycle times. To investigate the relationship between cell cycle regulation and pattern formation, we have identified a collection of embryonic-lethal mutants in which cell divisions are delayed and cell fate patterns are abnormal. In div (for division delayed) mutant embryos, embryonic cell divisions are delayed but remain asynchronous. Some div mutants produce well-differentiated cell types, but they frequently lack the endodermal and mesodermal cell fates normally specified by a transcriptional activator called SKN-1. We show that mislocalization of PIE-1, a negative regulator of SKN-1, prevents the specification of endoderm and mesoderm in div-1 mutant embryos. In addition to defects in the normally asymmetric distribution of PIE-1, div mutants also exhibit other losses of asymmetry during early embryonic cleavages. The daughters of normally asymmetric divisions are nearly equal in size, and cytoplasmic P-granules are not properly localized to germline precursors in div mutant embryos. Thus the proper timing of cell division appears to be important for multiple aspects of asymmetric cell division. One div gene, div-1, encodes the B subunit of the DNA polymerase alpha-primase complex. Reducing the function of other DNA replication genes also results in a delayed division phenotype and embryonic lethality. Thus the other div genes we have identified are likely to encode additional components of the DNA replication machinery in C. elegans.

  8. Cell growth characteristics from angle- and polarization-resolved light scattering: Prospects for two-dimensional correlation analysis (United States)

    Herran Cuspinera, Roxana M.; Hore, Dennis K.


    We highlight the potential of generalized two-dimensional correlation analysis for the fingerprinting of cell growth in solution monitored by light scattering, where the synchronous and asynchronous responses serve as a sensitive marker for the effect of growth conditions on the distribution of cell morphologies. The polarization of the scattered light varies according to the cell size distribution, and so the changes in the polarization over time are an excellent indicator of the dynamic growth conditions. However, direct comparison of the polarization-, time-, and angle-resolved signals between different experiments is hindered by the subtle changes in the data, and the inability to easily adapt models to account for these differences. Using Mie scattering simulations of different growth conditions, and some preliminary experimental data for a single set of conditions, we illustrate that correlation analysis provides rapid and sensitive qualitative markers of growth characteristics.

  9. Drosophila Rho-associated kinase (Drok) links Frizzled-mediated planar cell polarity signaling to the actin cytoskeleton. (United States)

    Winter, C G; Wang, B; Ballew, A; Royou, A; Karess, R; Axelrod, J D; Luo, L


    Frizzled (Fz) and Dishevelled (Dsh) are components of an evolutionarily conserved signaling pathway that regulates planar cell polarity. How this signaling pathway directs asymmetric cytoskeletal reorganization and polarized cell morphology remains unknown. Here, we show that Drosophila Rho-associated kinase (Drok) works downstream of Fz/Dsh to mediate a branch of the planar polarity pathway involved in ommatidial rotation in the eye and in restricting actin bundle formation to a single site in developing wing cells. The primary output of Drok signaling is regulating the phosphorylation of nonmuscle myosin regulatory light chain, and hence the activity of myosin II. Drosophila myosin VIIA, the homolog of the human Usher Syndrome 1B gene, also functions in conjunction with this newly defined portion of the Fz/Dsh signaling pathway to regulate the actin cytoskeleton.

  10. Mn bioavailability by polarized Caco-2 cells: comparison between Mn gluconate and Mn oxyprolinate

    Directory of Open Access Journals (Sweden)

    Fulgenzi Alessandro


    Full Text Available Abstract Background Micronutrient inadequate intake is responsible of pathological deficiencies and there is a need of assessing the effectiveness of metal supplementation, frequently proposed to rebalance poor diets. Manganese (Mn is present in many enzymatic intracellular systems crucial for the regulation of cell metabolism, and is contained in commercially available metal supplements. Methods We compared the effects of two different commercial Mn forms, gluconate (MnGluc and oxyprolinate (MnOxP. For this purpose we used the polarized Caco-2 cells cultured on transwell filters, an established in vitro model of intestinal epithelium. Since micronutrient deficiency may accelerate mitochondrial efficiency, the mitochondrial response of these cells, in the presence of MnGluc and MnOxP, by microscopy methods and by ATP luminescence assay was used. Results In the presence of both MnOxP and MnGluc a sustained mitochondrial activity was shown by mitoTraker labeling (indicative of mitochondrial respiration, but ATP intracellular content remained comparable to untreated cells only in the presence of MnOxP. In addition MnOxP transiently up-regulated the antioxidant enzyme Mn superoxide dismutase more efficiently than MnGluc. Both metal treatments preserved NADH and βNADPH diaphorase oxidative activity, avoided mitochondrial dysfunction, as assessed by the absence of a sustained phosphoERK activation, and were able to maintain cell viability. Conclusions Collectively, our data indicate that MnOxP and MnGluc, and primarily the former, produce a moderate and safe modification of Caco-2 cell metabolism, by activating positive enzymatic mechanisms, thus could contribute to long-term maintenance of cell homeostasis.

  11. Shifted T Helper Cell Polarization in a Murine Staphylococcus aureus Mastitis Model. (United States)

    Zhao, Yanqing; Zhou, Ming; Gao, Yang; Liu, Heyuan; Yang, Wenyu; Yue, Jinhua; Chen, Dekun


    Mastitis, one of the most costly diseases in dairy ruminants, is an inflammation of the mammary gland caused by pathogenic infection. The mechanisms of adaptive immunity against pathogens in mastitis have not been fully elucidated. To investigate T helper cell-mediated adaptive immune responses, we established a mastitis model by challenge with an inoculum of 4 × 106 colony-forming units of Staphylococcus aureus in the mammary gland of lactating mice, followed by quantification of bacterial burden and histological analysis. The development of mastitis was accompanied by a significant increase in both Th17 and Th1 cells in the mammary gland. Moreover, the relative expression of genes encoding cytokines and transcription factors involved in the differentiation and function of these T helper cells, including Il17, Rorc, Tgfb, Il1b, Il23, Ifng, Tbx21, and Il12, was greatly elevated in the infected mammary gland. IL-17 is essential for neutrophil recruitment to infected mammary gland via CXC chemokines, whereas the excessive IL-17 production contributes to tissue damage in mastitis. In addition, a shift in T helper cell polarization toward Th2 and Treg cells was observed 5 days post-infection, and the mRNA expression of the anti-inflammatory cytokine Il10 was markedly increased at day 7 post-infection. These results indicate that immune clearance of Staphylococcus aureus in mastitis is facilitated by the enrichment of Th17, Th1 and Th2 cells in the mammary gland mediated by pro-inflammatory cytokine production, which is tightly regulated by Treg cells and the anti-inflammatory cytokine IL-10.

  12. Assembly and positioning of actomyosin rings by contractility and planar cell polarity. (United States)

    Sehring, Ivonne M; Recho, Pierre; Denker, Elsa; Kourakis, Matthew; Mathiesen, Birthe; Hannezo, Edouard; Dong, Bo; Jiang, Di


    The actomyosin cytoskeleton is a primary force-generating mechanism in morphogenesis, thus a robust spatial control of cytoskeletal positioning is essential. In this report, we demonstrate that actomyosin contractility and planar cell polarity (PCP) interact in post-mitotic Ciona notochord cells to self-assemble and reposition actomyosin rings, which play an essential role for cell elongation. Intriguingly, rings always form at the cells' anterior edge before migrating towards the center as contractility increases, reflecting a novel dynamical property of the cortex. Our drug and genetic manipulations uncover a tug-of-war between contractility, which localizes cortical flows toward the equator and PCP, which tries to reposition them. We develop a simple model of the physical forces underlying this tug-of-war, which quantitatively reproduces our results. We thus propose a quantitative framework for dissecting the relative contribution of contractility and PCP to the self-assembly and repositioning of cytoskeletal structures, which should be applicable to other morphogenetic events.

  13. Diego and Prickle regulate Frizzled planar cell polarity signalling by competing for Dishevelled binding. (United States)

    Jenny, Andreas; Reynolds-Kenneally, Jessica; Das, Gishnu; Burnett, Micheal; Mlodzik, Marek


    Epithelial planar cell polarity (PCP) is evident in the cellular organization of many tissues in vertebrates and invertebrates. In mammals, PCP signalling governs convergent extension during gastrulation and the organization of a wide variety of structures, including the orientation of body hair and sensory hair cells of the inner ear. In Drosophila melanogaster, PCP is manifest in adult tissues, including ommatidial arrangement in the compound eye and hair orientation in wing cells. PCP establishment requires the conserved Frizzled/Dishevelled PCP pathway. Mutations in PCP-pathway-associated genes cause aberrant orientation of body hair or inner-ear sensory cells in mice, or misorientation of ommatidia and wing hair in D. melanogaster. Here we provide mechanistic insight into Frizzled/Dishevelled signalling regulation. We show that the ankyrin-repeat protein Diego binds directly to Dishevelled and promotes Frizzled signalling. Dishevelled can also be bound by the Frizzled PCP antagonist Prickle. Strikingly, Diego and Prickle compete with one another for Dishevelled binding, thereby modulating Frizzled/Dishevelled activity and ensuring tight control over Frizzled PCP signalling.

  14. Comparative study on power generation of dual-cathode microbial fuel cell according to polarization methods. (United States)

    Lee, Kang-yu; Ryu, Wyan-seuk; Cho, Sung-il; Lim, Kyeong-ho


    Microbial fuel cells (MFCs) exist in various forms depending on the type of pollutant to be removed and the expected performance. Dual-cathode MFCs, with their simple structure, are capable of removing both organic matter and nitrogen. Moreover, various methods are available for the collection of polarization data, which can be used to calculate the maximum power density, an important factor of MFCs. Many researchers prefer the method of varying the external resistance in a single-cycle due to the short measurement time and high accuracy. This study compared power densities of dual-cathode MFCs in a single-cycle with values calculated over multi-cycles to determine the optimal polarization method. External resistance was varied from high to low and vice versa in the single-cycle, to calculate power density. External resistance was organized in descending order with initial start-up at open circuit voltage (OCV), and then it was organized in descending order again after the initial start-up at 1000 Ω. As a result, power density was underestimated at the anoxic cathode when the external resistance was varied from low to high, and overestimated at the aerobic cathode and anoxic cathode when external resistance at OCV was reduced following initial start-up. In calculating the power densities of dual-cathode MFCs, this paper recommends the method of gradually reducing the external resistance after initial start-up with high external resistance.

  15. The effects of human umbilical cord perivascular cells on rat hepatocyte structure and functional polarity. (United States)

    Gómez-Aristizábal, Alejandro; Davies, John Edward


    Hepatocyte culture is a useful tool for the study of their biology and the development of bioartificial livers. However, many challenges have to be overcome since hepatocytes rapidly lose their normal phenotype in vitro. We have recently demonstrated that human umbilical cord perivascular cells (HUCPVCs) are able to provide support to hepatocytes. In the present study we go further into exploring the effects that HUCPVCs have in the functional polarization, and both the internal and external organization, of hepatocytes. Also, we investigate HUCPVC-hepatocyte crosstalk by tracking both the effects of HUCPVCs on hepatocyte transcription factors and those of hepatocytes on the expression of hepatotrophic factors in HUCPVCs. Our results show that HUCPVCs maintain the functional polarity of hepatocytes ex vivo, as judged by the secretion of fluorescein into bile canaliculi, for at least 40 days. Transmission electron microscopy revealed that hepatocytes in coculture organize in an organoid-like structure embedded in extracellular matrix surrounded by HUCPVCs. In coculture, hepatocytes displayed a higher expression of C/EBPα, implicated in maintenance of the mature hepatocyte phenotype, and HUCPVCs upregulated hepatocyte growth factor and Jagged1 indicating that these genes may play important roles in HUCPVC-hepatocyte interactions.

  16. Analysis of polarization methods for elimination of power overshoot in microbial fuel cells

    KAUST Repository

    Watson, Valerie J.


    Polarization curves from microbial fuel cells (MFCs) often show an unexpectedly large drop in voltage with increased current densities, leading to a phenomenon in the power density curve referred to as "power overshoot". Linear sweep voltammetry (LSV, 1 mV s- 1) and variable external resistances (at fixed intervals of 20 min) over a single fed-batch cycle in an MFC both resulted in power overshoot in power density curves due to anode potentials. Increasing the anode enrichment time from 30 days to 100 days did not eliminate overshoot, suggesting that insufficient enrichment of the anode biofilm was not the primary cause. Running the reactor at a fixed resistance for a full fed-batch cycle (~ 1 to 2 days), however, completely eliminated the overshoot in the power density curve. These results show that long times at a fixed resistance are needed to stabilize current generation by bacteria in MFCs, and that even relatively slow LSV scan rates and long times between switching circuit loads during a fed-batch cycle may produce inaccurate polarization and power density results for these biological systems. © 2010 Elsevier B.V. All rights reserved.

  17. Isoform-specific interaction of Flamingo/Starry Night with excess Bazooka affects planar cell polarity in the Drosophila wing. (United States)

    Wasserscheid, Isabel; Thomas, Ulrich; Knust, Elisabeth


    Epithelia display two types of polarity, apical-basal and planar cell polarity (PCP), and both are crucial for morphogenesis and organogenesis. PCP signaling pathways comprise transmembrane proteins, such as Flamingo/Starry Night, and cytoplasmic, membrane-associated proteins such as Dishevelled. During establishment of PCP in the Drosophila wing, PCP proteins accumulate apically in distinct "cortical domains" on proximal and distal plasma membranes. This finding suggests that their localized function depends on prior definition of apicobasal polarity. Here, we show that overexpression of Bazooka, a PDZ-domain protein essential for apicobasal polarity in the embryo, perturbs development of PCP, but has no effect on apicobasal polarity. The PCP phenotype is associated with a failure to restrict Flamingo/Starry night to the proximal and distal plasma membranes of the wing epithelium. We further demonstrate that flamingo expresses two differentially spliced RNAs in wing imaginal discs, which encode two isoforms of the atypical cadherin Flamingo. The predominant Starry night-type form contains a PDZ-binding motif, which mediates binding to Bazooka in vitro. Pull-down assays support the occurrence of such an interaction in wing imaginal discs. The results suggest that interaction between the apicobasal and planar cell polarity systems has to be tightly coordinated to ensure proper morphogenesis of the wing disc epithelium.

  18. The dual effects of polar methanolic extract of Hypericum perforatum L. in bladder cancer cells (United States)

    Nseyo, U. O.; Nseyo, O. U.; Shiverick, K. T.; Medrano, T.; Mejia, M.; Stavropoulos, N.; Tsimaris, I.; Skalkos, D.


    Introduction and background: We have reported on the polar methanolic fraction (PMF) of Hypericum Perforatum L as a novel photosensitizing agent for photodynamic therapy (PDT) and photodynamic diagnosis (PDD). PMF has been tested in human leukemic cells, HL-60 cells, cord blood hemopoietic progenitor cells, bladder cancers derived from metastatic lymph node (T-24) and primary papillary bladder lesion (RT-4). However, the mechanisms of the effects of PMF on these human cell lines have not been elucidated. We have investigated mechanisms of PMF + light versus PMF-alone (dark experiment) in T-24 human bladder cancer cells. Methods: PMF was prepared from an aerial herb of HPL which was brewed in methanol and extracted with ether and methanol. Stock solutions of PMF were made in DSMO and stored in dark conditions. PMF contains 0.57% hypericin and 2.52% hyperforin. The T24 cell line was obtained from American Type Culture Collection (ATCC). In PDT treatment, PMF (60μg/ml) was incubated with cells, which were excited with laser light (630nm) 24 hours later. Apoptosis was determined by DNA fragmentation/laddering assay. DNA isolation was performed according to the manufacture's instructions with the Kit (Oncogene Kit#AM41). Isolated DNA samples were separated by electrophoresis in 1.5% in agarose gels and bands were visualized by ethidium bromide labeling. The initial cell cycle analysis and phase distribution was by flow cytometry. DNA synthesis was measured by [3H] thymidine incorporation, and cell cycle regulatory proteins were assayed by Western immunoblot. Results: The results of the flow cytometry showed PMF +light induced significant (40%) apoptosis in T24 cells, whereas Light or PMF alone produced little apoptosis. The percentage of cells in G 0/G I phase was decreased by 25% and in G2/M phase by 38%. The main impact was observed on the S phase which was blocked by 78% from the specific photocytotoxic process. DNA laddering analysis showed that PMF (60

  19. In Vitro Polarized Resonance Raman Study of N719 and N719-TBP in Dye Sensitized Solar Cells

    DEFF Research Database (Denmark)

    Hassig, Søren; Jernshøj, Kit; Phuong, Nguyen Tuyet;


    The working efficiency of dye-sensitized solar cells (DSCs) depends on the long-term stability of the dye itself and on the microscopic structure of the dye-semiconductor interface. Previous experimental studies of DSCs based on ruthenium dye with bipyridine ligands (N719) adsorbed to the TiO2......substrate applied FTIR,un-polarized Raman (RS) and un-polarized resonance Raman (RRS) spectroscopy. In the un-polarized RRS studies of N719/TiO2 – DSCs the discussion of the adsorption of N719 was based on the rather weak carbonyl or carboxyl group stretching vibrations and on minor spectral changes...... of overlapping Raman modes, whereas conclusions about the dye-stability was based on the observation that fresh and aged DSCs had almost identical RRS spectra. In the present paper we address the problems mentioned above, by utilizing the unique property of Raman scattering that the polarization of the scattered...

  20. Endothelial Cell Migration and Vascular Endothelial Growth Factor Expression Are the Result of Loss of Breast Tissue Polarity

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Amy; Cuevas, Ileana; Kenny, Paraic A; Miyake, Hiroshi; Mace, Kimberley; Ghajar, Cyrus; Boudreau, Aaron; Bissell, Mina; Boudreau, Nancy


    Recruiting a new blood supply is a rate-limiting step in tumor progression. In a three-dimensional model of breast carcinogenesis, disorganized, proliferative transformed breast epithelial cells express significantly higher expression of angiogenic genes compared with their polarized, growth-arrested nonmalignant counterparts. Elevated vascular endothelial growth factor (VEGF) secretion by malignant cells enhanced recruitment of endothelial cells (EC) in heterotypic cocultures. Significantly, phenotypic reversion of malignant cells via reexpression of HoxD10, which is lost in malignant progression, significantly attenuated VEGF expression in a hypoxia-inducible factor 1{alpha}-independent fashion and reduced EC migration. This was due primarily to restoring polarity: forced proliferation of polarized, nonmalignant cells did not induce VEGF expression and EC recruitment, whereas disrupting the architecture of growth-arrested, reverted cells did. These data show that disrupting cytostructure activates the angiogenic switch even in the absence of proliferation and/or hypoxia and restoring organization of malignant clusters reduces VEGF expression and EC activation to levels found in quiescent nonmalignant epithelium. These data confirm the importance of tissue architecture and polarity in malignant progression.

  1. Role of the planar cell polarity pathway in regulating ectopic hair cell-like cells induced by Math1 and testosterone treatment. (United States)

    Yang, Xiao-Yu; Jin, Kai; Ma, Rui; Yang, Juan-Mei; Luo, Wen-Wei; Han, Zhao; Cong, Ning; Ren, Dong-Dong; Chi, Fang-Lu


    Planar cell polarity (PCP) signaling regulates cochlear extension and coordinates orientation of sensory hair cells in the inner ear. Retroviral-mediated introduction of the Math1 transcription factor leads to the transdifferentiation of some mature supporting cells into hair cells. Testosterone, a gonadal sex steroid hormone, is associated with neuroprotection and regeneration in Central Nervous System (CNS) development. Experiments were performed in vitro using Ad5-EGFP-Math1/Ad5-Math1 in neonatal mouse cochleas. Establishment of ectopic hair-cell like cell(HCLC) polarity in the lesser epithelial ridge (LER) with or without testosterone-3-(O-carboxymethyl) oxime bovine serum albumin (testosterone-BSA) treatment was investigated to determine the role of the PCP pathway in regulating ectopic regenerated (HCLCs) through induction by Math1 and testosterone treatment. After Math1 infection, new ectopic regenerated HCLCs were detected in the LER. After the HCLCs developed actin-rich stereocilia, the basal bodies moved from the center to the distal side. Moreover, the narrower, non-sensory LER region meant that the convergent extension (CE) was also established after transfection with Math1. After 9 days of in vitro testosterone-BSA treatment, more Edu(+), Sox2(+), and HCLC cells were observed in the LER with an accompanying downregulation of E-cadherin. Interestingly, the CE of the Ad5-EGFP-math1 treated LER is altered, but the intrinsic cellular polarity of the HCLCs is not obviously changed. In summary, our results indicate that PCP signaling is involved in the development of ectopic HCLCs and the CE of the ectopic sensory region is altered by testosterone-BSA through downregulation of cell-cell adhesion. Testosterone-BSA and Math1 treatment could promote an increase in HCLCs in the LER through proliferation and transdifferentiation.

  2. Effects of Butter and Phytanic acid intake on metabolic parameters and T-cell polarization

    DEFF Research Database (Denmark)

    Drachmann, Tue

    dairy fat in general and phytanic acid on metabolic parameters, we performed several studies. First, we investigated effects on hepatic lipid metabolism, glucose homeostasis, and circulating metabolic markers, of high fat diets based on butter from high- or low-yield production, a diet based on high...... oleic acid sunflower oil, and a diet based on grape-seed oil with high amount of linoleic acid, in diet induced obese mice. Second, we investigated phytanic acid effects on similar parameters in obese mice, both as dose response in butter based diets, and in grape-seed oil based diets with and without...... addition of phytanic acid. Third, we investigated butter and phytanic acid effects on human T-cell polarization, both by in vitro incubation with phytanic acid, and by a 12 weeks intervention with intake of butter. Finally, we performed two human interventions, first one with intake of butter and cheese...

  3. Dachsous-Dependent Asymmetric Localization of Spiny-Legs Determines Planar Cell Polarity Orientation in Drosophila

    Directory of Open Access Journals (Sweden)

    Tomonori Ayukawa


    Full Text Available In Drosophila, planar cell polarity (PCP molecules such as Dachsous (Ds may function as global directional cues directing the asymmetrical localization of PCP core proteins such as Frizzled (Fz. However, the relationship between Ds asymmetry and Fz localization in the eye is opposite to that in the wing, thereby causing controversy regarding how these two systems are connected. Here, we show that this relationship is determined by the ratio of two Prickle (Pk isoforms, Pk and Spiny-legs (Sple. Pk and Sple form different complexes with distinct subcellular localizations. When the amount of Sple is increased in the wing, Sple induces a reversal of PCP using the Ds-Ft system. A mathematical model demonstrates that Sple is the key regulator connecting Ds and the core proteins. Our model explains the previously noted discrepancies in terms of the differing relative amounts of Sple in the eye and wing.

  4. The Drosophila Cadherin Fat regulates tissue size and planar cell polarity through different domains.

    Directory of Open Access Journals (Sweden)

    Xuesong Zhao

    Full Text Available The Drosophila Cadherin Fat (Ft has been identified as a crucial regulator of tissue size and Planar Cell Polarity (PCP. However, the precise mechanism by which Ft regulates these processes remains unclear. In order to advance our understanding of the action of Ft, we have sought to identify the crucial Ft effector domains. Here we report that a small region of the Ft cytoplasmic domain (H2 region is both necessary and sufficient, when membrane localized, to support viability and prevent tissue overgrowth. Interestingly, the H2 region is dispensable for regulating PCP signaling, whereas the mutant Ft lacking the H2 region is fully capable of directing PCP. This result suggests that Ft's roles in PCP signaling and tissue size control are separable, and each can be carried out independently. Surprisingly, the crucial regions of Ft identified in our structure-function study do not overlap with the previously reported interaction regions with Atrophin, Dco, or Lowfat.

  5. Differential recruitment of Dishevelled provides signaling specificity in the planar cell polarity and Wingless signaling pathways. (United States)

    Axelrod, J D; Miller, J R; Shulman, J M; Moon, R T; Perrimon, N


    In Drosophila, planar cell polarity (PCP) signaling is mediated by the receptor Frizzled (Fz) and transduced by Dishevelled (Dsh). Wingless (Wg) signaling also requires Dsh and may utilize DFz2 as a receptor. Using a heterologous system, we show that Dsh is recruited selectively to the membrane by Fz but not DFz2, and this recruitment depends on the DEP domain but not the PDZ domain in Dsh. A mutation in the DEP domain impairs both membrane localization and the function of Dsh in PCP signaling, indicating that translocation is important for function. Further genetic and molecular analyses suggest that conserved domains in Dsh function differently during PCP and Wg signaling, and that divergent intracellular pathways are activated. We propose that Dsh has distinct roles in PCP and Wg signaling. The PCP signal may selectively result in focal Fz activation and asymmetric relocalization of Dsh to the membrane, where Dsh effects cytoskeletal reorganization to orient prehair initiation.

  6. Planar cell polarity and a potential role for a Wnt morphogen gradient in stereociliary bundle orientation in the mammalian inner ear. (United States)

    Dabdoub, Alain; Kelley, Matthew W


    The planar cell polarity (PCP) pathway, a noncanonical Wnt signaling pathway, is crucial for embryonic development in all animals as it is responsible for the regulation of coordinated orientation of structures within the plane of the various epithelia. In the mammalian cochlea, one of the best examples of planar polarity in vertebrates, stereociliary bundles located on mechanosensory hair cells within the sensory epithelium are all uniformly polarized. Generation of this polarity is important for hair cell mechanotransduction and auditory perception as stereociliary bundles are only sensitive to vibrations in their single plane of polarization. We describe the two step developmental process that results in the generation of planar polarity in the mammalian inner ear. Furthermore, we review evidence for the role of Wnt signaling, and the possible generation of a Wnt gradient, in planar polarity.

  7. Planar cell polarity enables posterior localization of nodal cilia and left-right axis determination during mouse and Xenopus embryogenesis.

    Directory of Open Access Journals (Sweden)

    Dragana Antic

    Full Text Available Left-right asymmetry in vertebrates is initiated in an early embryonic structure called the ventral node in human and mouse, and the gastrocoel roof plate (GRP in the frog. Within these structures, each epithelial cell bears a single motile cilium, and the concerted beating of these cilia produces a leftward fluid flow that is required to initiate left-right asymmetric gene expression. The leftward fluid flow is thought to result from the posterior tilt of the cilia, which protrude from near the posterior portion of each cell's apical surface. The cells, therefore, display a morphological planar polarization. Planar cell polarity (PCP is manifested as the coordinated, polarized orientation of cells within epithelial sheets, or as directional cell migration and intercalation during convergent extension. A set of evolutionarily conserved proteins regulates PCP. Here, we provide evidence that vertebrate PCP proteins regulate planar polarity in the mouse ventral node and in the Xenopus gastrocoel roof plate. Asymmetric anterior localization of VANGL1 and PRICKLE2 (PK2 in mouse ventral node cells indicates that these cells are planar polarized by a conserved molecular mechanism. A weakly penetrant Vangl1 mutant phenotype suggests that compromised Vangl1 function may be associated with left-right laterality defects. Stronger functional evidence comes from the Xenopus GRP, where we show that perturbation of VANGL2 protein function disrupts the posterior localization of motile cilia that is required for leftward fluid flow, and causes aberrant expression of the left side-specific gene Nodal. The observation of anterior-posterior PCP in the mouse and in Xenopus embryonic organizers reflects a strong evolutionary conservation of this mechanism that is important for body plan determination.

  8. Keeping out the oxygen

    NARCIS (Netherlands)

    de Jongh, P.E.


    Hydrogen, the lightest of the elements, is expected to play a major role in our future energy economy. Its staggering energy content of 142 MJ kg-1 exceeds that of petroleum by a factor of three. Moreover, the combustion of hydrogen, as well as its use in electricity-producing fuel cells, is not ass

  9. NO2 inhalation induces maturation of pulmonary CD11c+ cells that promote antigenspecific CD4+ T cell polarization

    Directory of Open Access Journals (Sweden)

    Suratt Benjamin T


    -exposed mice produced IL-1, IL-12p70, and IL-6 in vitro and augmented antigen-induced IL-5 production. Conclusions CD11c+ cells are critical for NO2-promoted allergic sensitization. NO2 exposure causes pulmonary CD11c+ cells to acquire a phenotype capable of increased antigen uptake, migration to the draining lymph node, expression of MHCII and co-stimulatory molecules required to activate naïve T cells, and secretion of polarizing cytokines to shape a Th2/Th17 response.

  10. Cell cycle coordination and regulation of bacterial chromosome segregation dynamics by polarly localized proteins. (United States)

    Schofield, Whitman B; Lim, Hoong Chuin; Jacobs-Wagner, Christine


    What regulates chromosome segregation dynamics in bacteria is largely unknown. Here, we show in Caulobacter crescentus that the polarity factor TipN regulates the directional motion and overall translocation speed of the parS/ParB partition complex by interacting with ParA at the new pole. In the absence of TipN, ParA structures can regenerate behind the partition complex, leading to stalls and back-and-forth motions of parS/ParB, reminiscent of plasmid behaviour. This extrinsic regulation of the parS/ParB/ParA system directly affects not only division site selection, but also cell growth. Other mechanisms, including the pole-organizing protein PopZ, compensate for the defect in segregation regulation in ΔtipN cells. Accordingly, synthetic lethality of PopZ and TipN is caused by severe chromosome segregation and cell division defects. Our data suggest a mechanistic framework for adapting a self-organizing oscillator to create motion suitable for chromosome segregation.

  11. p/n-Polarity of thiophene oligomers in photovoltaic cells: role of molecular vs. supramolecular properties. (United States)

    Ghosh, Tanwistha; Gopal, Anesh; Saeki, Akinori; Seki, Shu; Nair, Vijayakumar C


    Molecular and supramolecular properties play key roles in the optoelectronic properties and photovoltaic performances of organic materials. In the present work, we show how small changes in the molecular structure affect such properties, which in turn control the intrinsic and fundamental properties such as the p/n-polarity of organic semiconductors in bulk-heterojunction solar cells. Herein, we designed and synthesized two acceptor-donor-acceptor type semiconducting thiophene oligomers end-functionalized with oxazolone/isoxazolone derivatives (OT1 and OT2 respectively). The HOMO-LUMO energy levels of both derivatives were found to be positioned in such a way that they can act as electron acceptors to P3HT and electron donors to PCBM. However, OT1 functions as a donor (with PCBM) and OT2 as an acceptor (with P3HT) in BHJ photovoltaic cells, and their reverse roles results in either no or poor performance of the cells. Detailed studies using UV-vis absorption and fluorescence spectroscopy, time-correlated single photon counting, UV-photoelectron spectroscopy, density functional theory calculations, X-ray diffraction, and thermal gravimetric analysis proved that both molecular and supramolecular properties contributed equally but in a contrasting manner to the abovementioned observation. The obtained results were further validated by flash-photolysis time-resolved microwave conductivity studies which showed an excellent correlation between the structure, property, and device performances of the materials.

  12. Polarization birefringence measurements for characterizing the myocardium, including healthy, infarcted, and stem-cell-regenerated tissues (United States)

    Wood, Michael F. G.; Ghosh, Nirmalya; Wallenburg, Marika A.; Li, Shu-Hong; Weisel, Richard D.; Wilson, Brian C.; Li, Ren-Ke; Vitkin, I. Alex


    Myocardial infarction leads to structural remodeling of the myocardium, in particular to the loss of cardiomyocytes due to necrosis and an increase in collagen with scar formation. Stem cell regenerative treatments have been shown to alter this remodeling process, resulting in improved cardiac function. As healthy myocardial tissue is highly fibrous and anisotropic, it exhibits optical linear birefringence due to the different refractive indices parallel and perpendicular to the fibers. Accordingly, changes in myocardial structure associated with infarction and treatment-induced remodeling will alter the anisotropy exhibited by the tissue. Polarization-based linear birefringence is measured on the myocardium of adult rat hearts after myocardial infarction and compared with hearts that had received mesenchymal stem cell treatment. Both point measurement and imaging data show a decrease in birefringence in the region of infarction, with a partial rebound back toward the healthy values following regenerative treatment with stem cells. These results demonstrate the ability of optical polarimetry to characterize the micro-organizational state of the myocardium via its measured anisotropy, and the potential of this approach for monitoring regenerative treatments of myocardial infarction.

  13. Polarizing T and B cell responses by APC-targeted subunit vaccines.

    Directory of Open Access Journals (Sweden)

    Gunnveig eGrødeland


    Full Text Available Current influenza vaccines mostly aim at the induction of specific neutralizing antibodies. While antibodies are important for protection against a particular virus strain, T cells can recognize epitopes that will offer broader protection against influenza. We have previously developed a DNA vaccine format by which protein antigens can be targeted specifically to receptors on antigen presenting cells (APCs. The DNA-encoded vaccine proteins are homodimers, each chain consisting of a targeting unit, a dimerization unit, and an antigen. The strategy of targeting antigen to APCs greatly enhances immune responses as compared to non-targeted controls. Furthermore, targeting of antigen to different receptors on APCs can polarize the immune response to different arms of immunity. Here, we discuss how targeting of hemagglutinin (HA to MHC class II molecules increases Th2 and IgG1 antibody responses, whereas targeting to chemokine receptors XCR1 or CCR1/3/5 increases Th1 and IgG2a responses, in addition to CD8+ T cell responses. We also discuss these results in relation to work published by others on APC-targeting. Differential targeting of APC surface molecules may allow the induction of tailor-made phenotypes of adaptive immune responses that are optimal for protection against various infectious agents, including influenza virus.

  14. The Arctic and Polar cells act on the Arctic sea ice variation

    Directory of Open Access Journals (Sweden)

    Weihong Qian


    Full Text Available The Arctic sea ice has undergone a substantial long-term decline with superimposed interannual sea ice minimum (SIM events over the last decades. This study focuses on the relationship between atmospheric circulation and the SIM events in the Arctic region. Four reanalysis products and simulations of one climate model are first analysed to confirm the existence of the Arctic cell, a meridional circulation cell to the north of 80°N, by visualising through the mean streamline and mean mass stream function in the Northern Hemisphere. Dynamical analyses of zonally averaged stationary eddy heat and momentum fluxes as well as the global precipitation rate data further confirm its existence. Finally, we found that the change in the Arctic sea ice concentration lags the variations of the descending air flow intensity associated with the Polar and Arctic cells, by about 2 months for the climatic annual cycle and about 10 months for the interannual anomaly. Five Arctic SIM events during the last three decades support this relationship. These results have implications for understanding the relationship between atmospheric circulation and sea-ice variations, and for predicting the Arctic sea ice changes.

  15. Vangl-dependent planar cell polarity signalling is not required for neural crest migration in mammals. (United States)

    Pryor, Sophie E; Massa, Valentina; Savery, Dawn; Andre, Philipp; Yang, Yingzi; Greene, Nicholas D E; Copp, Andrew J


    The role of planar cell polarity (PCP) signalling in neural crest (NC) development is unclear. The PCP dependence of NC cell migration has been reported in Xenopus and zebrafish, but NC migration has not been studied in mammalian PCP mutants. Vangl2(Lp/Lp) mouse embryos lack PCP signalling and undergo almost complete failure of neural tube closure. Here we show, however, that NC specification, migration and derivative formation occur normally in Vangl2(Lp/Lp) embryos. The gene family member Vangl1 was not expressed in NC nor ectopically expressed in Vangl2(Lp/Lp) embryos, and doubly homozygous Vangl1/Vangl2 mutants exhibited normal NC migration. Acute downregulation of Vangl2 in the NC lineage did not prevent NC migration. In vitro, Vangl2(Lp/Lp) neural tube explants generated emigrating NC cells, as in wild type. Hence, PCP signalling is not essential for NC migration in mammals, in contrast to its essential role in neural tube closure. PCP mutations are thus unlikely to mediate NC-related birth defects in humans.

  16. Genetic evidence that Drosophila frizzled controls planar cell polarity and Armadillo signaling by a common mechanism. (United States)

    Povelones, Michael; Howes, Rob; Fish, Matt; Nusse, Roel


    The frizzled (fz) gene in Drosophila controls two distinct signaling pathways: it directs the planar cell polarization (PCP) of epithelia and it regulates cell fate decisions through Armadillo (Arm) by acting as a receptor for the Wnt protein Wingless (Wg). With the exception of dishevelled (dsh), the genes functioning in these two pathways are distinct. We have taken a genetic approach, based on a series of new and existing fz alleles, for identifying individual amino acids required for PCP or Arm signaling. For each allele, we have attempted to quantify the strength of signaling by phenotypic measurements. For PCP signaling, the defect was measured by counting the number of cells secreting multiple hairs in the wing. We then examined each allele for its ability to participate in Arm signaling by the rescue of fz mutant embryos with maternally provided fz function. For both PCP and Arm signaling we observed a broad range of phenotypes, but for every allele there is a strong correlation between its phenotypic strength in each pathway. Therefore, even though the PCP and Arm signaling pathways are genetically distinct, the set of signaling-defective fz alleles affected both pathways to a similar extent. This suggests that fz controls these two different signaling activities by a common mechanism. In addition, this screen yielded a set of missense mutations that identify amino acids specifically required for fz signaling function.

  17. Shroom3 functions downstream of planar cell polarity to regulate myosin II distribution and cellular organization during neural tube closure

    Directory of Open Access Journals (Sweden)

    Erica M. McGreevy


    Full Text Available Neural tube closure is a critical developmental event that relies on actomyosin contractility to facilitate specific processes such as apical constriction, tissue bending, and directional cell rearrangements. These complicated processes require the coordinated activities of Rho-Kinase (Rock, to regulate cytoskeletal dynamics and actomyosin contractility, and the Planar Cell Polarity (PCP pathway, to direct the polarized cellular behaviors that drive convergent extension (CE movements. Here we investigate the role of Shroom3 as a direct linker between PCP and actomyosin contractility during mouse neural tube morphogenesis. In embryos, simultaneous depletion of Shroom3 and the PCP components Vangl2 or Wnt5a results in an increased liability to NTDs and CE failure. We further show that these pathways intersect at Dishevelled, as Shroom3 and Dishevelled 2 co-distribute and form a physical complex in cells. We observed that multiple components of the Shroom3 pathway are planar polarized along mediolateral cell junctions in the neural plate of E8.5 embryos in a Shroom3 and PCP-dependent manner. Finally, we demonstrate that Shroom3 mutant embryos exhibit defects in planar cell arrangement during neural tube closure, suggesting a role for Shroom3 activity in CE. These findings support a model in which the Shroom3 and PCP pathways interact to control CE and polarized bending of the neural plate and provide a clear illustration of the complex genetic basis of NTDs.

  18. Shroom3 functions downstream of planar cell polarity to regulate myosin II distribution and cellular organization during neural tube closure. (United States)

    McGreevy, Erica M; Vijayraghavan, Deepthi; Davidson, Lance A; Hildebrand, Jeffrey D


    Neural tube closure is a critical developmental event that relies on actomyosin contractility to facilitate specific processes such as apical constriction, tissue bending, and directional cell rearrangements. These complicated processes require the coordinated activities of Rho-Kinase (Rock), to regulate cytoskeletal dynamics and actomyosin contractility, and the Planar Cell Polarity (PCP) pathway, to direct the polarized cellular behaviors that drive convergent extension (CE) movements. Here we investigate the role of Shroom3 as a direct linker between PCP and actomyosin contractility during mouse neural tube morphogenesis. In embryos, simultaneous depletion of Shroom3 and the PCP components Vangl2 or Wnt5a results in an increased liability to NTDs and CE failure. We further show that these pathways intersect at Dishevelled, as Shroom3 and Dishevelled 2 co-distribute and form a physical complex in cells. We observed that multiple components of the Shroom3 pathway are planar polarized along mediolateral cell junctions in the neural plate of E8.5 embryos in a Shroom3 and PCP-dependent manner. Finally, we demonstrate that Shroom3 mutant embryos exhibit defects in planar cell arrangement during neural tube closure, suggesting a role for Shroom3 activity in CE. These findings support a model in which the Shroom3 and PCP pathways interact to control CE and polarized bending of the neural plate and provide a clear illustration of the complex genetic basis of NTDs.

  19. Interactions between Fat and Dachsous and the regulation of planar cell polarity in the Drosophila wing. (United States)

    Matakatsu, Hitoshi; Blair, Seth S


    It was recently suggested that a proximal to distal gradient of the protocadherin Dachsous (Ds) acts as a cue for planar cell polarity (PCP) in the Drosophila wing, orienting cell-cell interactions by inhibiting the activity of the protocadherin Fat (Ft). This Ft-Ds signaling model is based on mutant loss-of-function phenotypes, leaving open the question of whether Ds is instructive or permissive for PCP. We developed tools for misexpressing ds and ft in vitro and in vivo, and have used these to test aspects of the model. First, this model predicts that Ds and Ft can bind. We show that Ft and Ds mediate preferentially heterophilic cell adhesion in vitro, and that each stabilizes the other on the cell surface. Second, the model predicts that artificial gradients of Ds are sufficient to reorient PCP in the wing; our data confirms this prediction. Finally, loss-of-function phenotypes suggest that the gradient of ds expression is necessary for correct PCP throughout the wing. Surprisingly, this is not the case. Uniform levels of ds drive normally oriented PCP and, in all but the most proximal regions of the wing, uniform ds rescues the ds mutant PCP phenotype. Nor are distal PCP defects increased by the loss of spatial information from the distally expressed four-jointed (fj) gene, which encodes putative modulator of Ft-Ds signaling. Thus, while our results support the existence of Ft-Ds binding and show that it is sufficient to alter PCP, ds expression is permissive or redundant with other PCP cues in much of the wing.

  20. Transcriptome analysis of soybean leaf abscission identifies transcriptional regulators of organ polarity and cell fate

    Directory of Open Access Journals (Sweden)

    Joonyup eKim


    Full Text Available Abscission, organ separation, is a developmental process that is modulated by endogenous and environmental factors. To better understand the molecular events underlying the progression of abscission in soybean, an agriculturally important legume, we performed RNA sequencing (RNA-seq of RNA isolated from the leaf abscission zones (LAZ and petioles (Non-AZ, NAZ after treating stem/petiole explants with ethylene for 0, 12, 24, 48, and 72 h. As expected, expression of several families of cell wall modifying enzymes and many pathogenesis-related (PR genes specifically increased in the LAZ as abscission progressed. Here, we focus on the 5,206 soybean genes we identified as encoding transcription factors (TFs. Of the 5,206 TFs, 1,088 were differentially up- or down-regulated more than 8-fold in the LAZ over time, and, within this group, 188 of the TFs were differentially regulated more than 8-fold in the LAZ relative to the NAZ. These 188 abscission-specific TFs include several TFs containing domains for homeobox, MYB, Zinc finger, bHLH, AP2, NAC, WRKY, YABBY, and auxin-related motifs. To discover the connectivity among the TFs and highlight developmental processes that support organ separation, the 188 abscission-specific TFs were then clustered based on a >4-fold up- or down-regulation in two consecutive time points (i.e., 0 h and 12 h, 12 h and 24 h, 24 h and 48 h, or 48 h and 72 h. By requiring a sustained change in expression over two consecutive time intervals and not just one or several time intervals, we could better tie changes in TFs to a particular process or phase of abscission. The greatest number of TFs clustered into the 0 h and 12 h group. Transcriptional network analysis for these abscission-specific TFs indicated that most of these TFs are known as key determinants in the maintenance of organ polarity, lateral organ growth and cell fate. The abscission-specific expression of these TFs prior to the onset of abscission and their

  1. Transcriptome Analysis of Soybean Leaf Abscission Identifies Transcriptional Regulators of Organ Polarity and Cell Fate. (United States)

    Kim, Joonyup; Yang, Jinyoung; Yang, Ronghui; Sicher, Richard C; Chang, Caren; Tucker, Mark L


    Abscission, organ separation, is a developmental process that is modulated by endogenous and environmental factors. To better understand the molecular events underlying the progression of abscission in soybean, an agriculturally important legume, we performed RNA sequencing (RNA-seq) of RNA isolated from the leaf abscission zones (LAZ) and petioles (Non-AZ, NAZ) after treating stem/petiole explants with ethylene for 0, 12, 24, 48, and 72 h. As expected, expression of several families of cell wall modifying enzymes and many pathogenesis-related (PR) genes specifically increased in the LAZ as abscission progressed. Here, we focus on the 5,206 soybean genes we identified as encoding transcription factors (TFs). Of the 5,206 TFs, 1,088 were differentially up- or down-regulated more than eight-fold in the LAZ over time, and, within this group, 188 of the TFs were differentially regulated more than eight-fold in the LAZ relative to the NAZ. These 188 abscission-specific TFs include several TFs containing domains for homeobox, MYB, Zinc finger, bHLH, AP2, NAC, WRKY, YABBY, and auxin-related motifs. To discover the connectivity among the TFs and highlight developmental processes that support organ separation, the 188 abscission-specific TFs were then clustered based on a >four-fold up- or down-regulation in two consecutive time points (i.e., 0 and 12 h, 12 and 24 h, 24 and 48 h, or 48 and 72 h). By requiring a sustained change in expression over two consecutive time intervals and not just one or several time intervals, we could better tie changes in TFs to a particular process or phase of abscission. The greatest number of TFs clustered into the 0 and 12 h group. Transcriptional network analysis for these abscission-specific TFs indicated that most of these TFs are known as key determinants in the maintenance of organ polarity, lateral organ growth, and cell fate. The abscission-specific expression of these TFs prior to the onset of abscission and their functional

  2. The Fz-Dsh Planar Cell Polarity Pathway Induces Oriented Cell Division via Mud/NuMA in Drosophila and Zebrafish



    The Frizzled receptor and Dishevelled effector regulate mitotic spindle orientation in both vertebrates and invertebrates, but how Dishevelled orients the mitotic spindle is unknown. Using the Drosophila S2 cell "induced polarity" system, we find that Dishevelled cortical polarity is sufficient to orient the spindle, and that Dishevelled's DEP domain mediates this function. This domain binds a C-terminal domain of Mud (the Drosophila NuMA ortholog), and Mud is required for Dishevelled-mediate...

  3. Exon loss accounts for differential sorting of Na-K-Cl cotransporters in polarized epithelial cells. (United States)

    Carmosino, Monica; Giménez, Ignacio; Caplan, Michael; Forbush, Biff


    The renal Na-K-Cl cotransporter (NKCC2) is selectively expressed in the apical membranes of cells of the mammalian kidney, where it is the target of the clinically important loop diuretics. In contrast, the "secretory" NKCC1 cotransporter is localized in the basolateral membranes of many epithelia. To identify the sorting signal(s) that direct trafficking of NKCCs, we generated chimeras between the two isoforms and expressed these constructs in polarized renal epithelial cell lines. This analysis revealed an amino acid stretch in NKCC2 containing apical sorting information. The NKCC1 C terminus contains a dileucine motif that constitutes the smallest essential component of its basolateral sorting signal. NKCC1 lacking this motif behaves as an apical protein. Examination of the NKCC gene structure reveals that this dileucine motif is encoded by an additional exon in NKCC1 absent in NKCC2. Phylogenetic analysis of this exon suggests that the evolutionary loss of this exon from the gene encoding the basolateral NKCC1 constitutes a novel mechanism that accounts for the apical sorting of the protein encoded by the NKCC2 gene.

  4. Diego interacts with Prickle and Strabismus/Van Gogh to localize planar cell polarity complexes. (United States)

    Das, Gishnu; Jenny, Andreas; Klein, Thomas J; Eaton, Suzanne; Mlodzik, Marek


    Planar cell polarity (PCP) in the Drosophila eye is established by the distinct fate specifications of photoreceptors R3 and R4, and is regulated by the Frizzled (Fz)/PCP signaling pathway. Before the PCP proteins become asymmetrically localized to opposite poles of the cell in response to Fz/PCP signaling, they are uniformly apically colocalized. Little is known about how the apical localization is maintained. We provide evidence that the PCP protein Diego (Dgo) promotes the maintenance of apical localization of Flamingo (Fmi), an atypical Cadherin-family member, which itself is required for the apical localization of the other PCP factors. This function of Dgo is redundant with Prickle (Pk) and Strabismus (Stbm), and only appreciable in double mutant tissue. We show that the initial membrane association of Dgo depends on Fz, and that Dgo physically interacts with Stbm and Pk through its Ankyrin repeats, providing evidence for a PCP multiprotein complex. These interactions suggest a positive feedback loop initiated by Fz that results in the apical maintenance of other PCP factors through Fmi.

  5. Influence of particle size and concentration on the diffuse backscattering of polarized light from tissue phantoms and biological cell suspensions

    Energy Technology Data Exchange (ETDEWEB)

    Hielscher, A.H.; Mourant, J.R.; Bigio, I.J. [Los Alamos National Laboratory, Bioscience and Biotechnology, CST-4, MS E535, Los Alamos, New Mexico 87545 (United States)


    We present experimental results that show the spatial variations of the diffuse-backscattered intensity when linearly polarized light is incident upon highly scattering media. Experiments on polystyrene-sphere and Intralipid suspensions demonstrate that the radial and azimuthal variations of the observed pattern depend on the concentration, and anisotropy factor {ital g} of the particles that constitute the scattering medium. Measurements performed on biological-cell suspensions show the potential of this method for cell characterization. {copyright} 1997 Optical Society of America

  6. DLG5 connects cell polarity and Hippo signaling protein networks by linking PAR-1 with MST1/2. (United States)

    Kwan, Julian; Sczaniecka, Anna; Arash, Emad Heidary; Nguyen, Liem; Chen, Chia-Chun; Ratkovic, Srdjana; Klezovitch, Olga; Attisano, Liliana; McNeill, Helen; Emili, Andrew; Vasioukhin, Valeri


    Disruption of apical-basal polarity is implicated in developmental disorders and cancer; however, the mechanisms connecting cell polarity proteins with intracellular signaling pathways are largely unknown. We determined previously that membrane-associated guanylate kinase (MAGUK) protein discs large homolog 5 (DLG5) functions in cell polarity and regulates cellular proliferation and differentiation via undefined mechanisms. We report here that DLG5 functions as an evolutionarily conserved scaffold and negative regulator of Hippo signaling, which controls organ size through the modulation of cell proliferation and differentiation. Affinity purification/mass spectrometry revealed a critical role of DLG5 in the formation of protein assemblies containing core Hippo kinases mammalian ste20 homologs 1/2 (MST1/2) and Par-1 polarity proteins microtubule affinity-regulating kinases 1/2/3 (MARK1/2/3). Consistent with this finding, Hippo signaling is markedly hyperactive in mammalian Dlg5(-/-) tissues and cells in vivo and ex vivo and in Drosophila upon dlg5 knockdown. Conditional deletion of Mst1/2 fully rescued the phenotypes of brain-specific Dlg5 knockout mice. Dlg5 also interacts genetically with Hippo effectors Yap1/Taz Mechanistically, we show that DLG5 inhibits the association between MST1/2 and large tumor suppressor homologs 1/2 (LATS1/2), uses its scaffolding function to link MST1/2 with MARK3, and inhibits MST1/2 kinase activity. These data reveal a direct connection between cell polarity proteins and Hippo, which is essential for proper development of multicellular organisms.

  7. Bonzo/CXCR6 expression defines type 1–polarized T-cell subsets with extralymphoid tissue homing potential (United States)

    Kim, Chang H.; Kunkel, Eric J.; Boisvert, Judie; Johnston, Brent; Campbell, James J.; Genovese, Mark C.; Greenberg, Harry B.; Butcher, Eugene C.


    Chemokine receptor expression is finely controlled during T-cell development. We show that newly identified chemokine receptor Bonzo/CXCR6 is expressed by subsets of Th1 or T-cytotoxic 1 (Tc1) cells, but not by Th2 or Tc2 cells, establishing Bonzo as a differential marker of polarized type 1 T cells in vitro and in vivo. Priming of naive T cells by dendritic cells induces expression of Bonzo on T cells. IL-12 enhances this dendritic cell–dependent upregulation, while IL-4 inhibits it. In blood, 35–56% of Bonzo+ CD4 T cells are Th1 cells, and 60–65% of Bonzo+ CD8 T cells are Tc1 cells, while few Bonzo+ cells are type 2 T cells. Almost all Bonzo+ Tc1 cells contain preformed granzyme A and display cytotoxic effector phenotype. Most Bonzo+ T cells lack L-selectin and/or CCR7, homing receptors for lymphoid tissues. Instead, Bonzo+ T cells are dramatically enriched among T cells in tissue sites of inflammation, such as rheumatoid joints and inflamed livers. Bonzo may be important in trafficking of effector T cells that mediate type 1 inflammation, making it a potential target for therapeutic modulation of inflammatory diseases. PMID:11238560

  8. The influence of non polar and polar molecules in mouse motile cells membranes and pure lipid bilayers.

    Directory of Open Access Journals (Sweden)

    Francisco J Sierra-Valdez

    Full Text Available We report an experimental study of mouse sperm motility that shows chief aspects characteristic of neurons: the anesthetic (produced by tetracaine and excitatory (produced by either caffeine or calcium effects and their antagonic action. While tetracaine inhibits sperm motility and caffeine has an excitatory action, the combination of these two substances balance the effects, producing a motility quite similar to that of control cells. We also study the effects of these agents (anesthetic and excitatory on the melting points of pure lipid liposomes constituted by 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC and dipalmitoyl phosphatidic acid (DPPA. Tetracaine induces a large fluidization of the membrane, shifting the liposomes melting transition temperature to much lower values. The effect of caffeine is null, but its addition to tetracaine-doped liposomes greatly screen the fluidization effect. A high calcium concentration stiffens pure lipid membranes and strongly reduces the effect of tetracaine. Molecular Dynamics Simulations are performed to further understand our experimental findings at the molecular level. We find a strong correlation between the effect of antagonic molecules that could explain how the mechanical properties suitable for normal cell functioning are affected and recovered.

  9. Cdc42-dependent Modulation of Tight Junctions and Membrane Protein Traffic in Polarized Madin-Darby Canine Kidney Cells (United States)

    Rojas, Raul; Ruiz, Wily G.; Leung, Som-Ming; Jou, Tzuu-Shuh; Apodaca, Gerard


    Polarized epithelial cells maintain the asymmetric composition of their apical and basolateral membrane domains by at least two different processes. These include the regulated trafficking of macromolecules from the biosynthetic and endocytic pathway to the appropriate membrane domain and the ability of the tight junction to prevent free mixing of membrane domain-specific proteins and lipids. Cdc42, a Rho family GTPase, is known to govern cellular polarity and membrane traffic in several cell types. We examined whether this protein regulated tight junction function in Madin-Darby canine kidney cells and pathways that direct proteins to the apical and basolateral surface of these cells. We used Madin-Darby canine kidney cells that expressed dominant-active or dominant-negative mutants of Cdc42 under the control of a tetracycline-repressible system. Here we report that expression of dominant-active Cdc42V12 or dominant-negative Cdc42N17 altered tight junction function. Expression of Cdc42V12 slowed endocytic and biosynthetic traffic, and expression of Cdc42N17 slowed apical endocytosis and basolateral to apical transcytosis but stimulated biosynthetic traffic. These results indicate that Cdc42 may modulate multiple cellular pathways required for the maintenance of epithelial cell polarity. PMID:11514615

  10. The planar cell polarity protein Vangl2 is required for retinal axon guidance. (United States)

    Leung, Vicki; Iliescu, Alexandra; Jolicoeur, Christine; Gravel, Michel; Apuzzo, Sergio; Torban, Elena; Cayouette, Michel; Gros, Philippe


    Vangl2 plays a critical role in the establishment of planar cell polarity (PCP). Previously, we detected expression of Vangl2 in the developing retina during late embryogenesis, which led us to investigate the possible role of Vangl2-mediated PCP signaling in eye development. We have generated a Vangl2(BGeo) knock-in mouse allowing us to evaluate Vangl2 mRNA expression during retinal development, and used an isoform-specific antibody to examine Vangl2 protein expression in cryosections. To investigate the role of Vangl2 in retinal development, we examined eyes taken from embryos homozygous for independent alleles of Looptail (Lp, Lp(m1jus) ) mutant mice. We found that Vangl2 mRNA and protein are dynamically expressed in the developing embryonic and postnatal retina, with Vangl2 expression becoming progressively restricted to the ganglion cell layer and optic nerve as the retina matures. The expression pattern of Vangl2 transcript and protein is most prominent in retinal ganglion cells (RGC), and their axons. Additionally, we show that Vangl2 is required for retinal and optic nerve development as Vangl2 (Lp/Lp) mutant embryos display a significantly reduced eye size, marked thickening of the retina, and striking abnormalities in the morphology of the optic nerve (significant hypoplasia, and aberrant exit trajectory). Notably, we identified a salient intraretinal axon guidance defect in Vangl2 (Lp/Lp) mutant embryos through which axon bundles traverse the entire thickness of the retina and become trapped within the subretinal space. Our observations identify a new and essential role for Vangl2-dependent PCP signaling in the intraretinal path-finding of RGC axons.

  11. Autofocus Correction of Azimuth Phase Error and Residual Range Cell Migration in Spotlight SAR Polar Format Imagery

    CERN Document Server

    Mao, Xinhua; Zhu, Zhaoda


    Synthetic aperture radar (SAR) images are often blurred by phase perturbations induced by uncompensated sensor motion and /or unknown propagation effects caused by turbulent media. To get refocused images, autofocus proves to be useful post-processing technique applied to estimate and compensate the unknown phase errors. However, a severe drawback of the conventional autofocus algorithms is that they are only capable of removing one-dimensional azimuth phase errors (APE). As the resolution becomes finer, residual range cell migration (RCM), which makes the defocus inherently two-dimensional, becomes a new challenge. In this paper, correction of APE and residual RCM are presented in the framework of polar format algorithm (PFA). First, an insight into the underlying mathematical mechanism of polar reformatting is presented. Then based on this new formulation, the effect of polar reformatting on the uncompensated APE and residual RCM is investigated in detail. By using the derived analytical relationship betwee...

  12. Gravity and light control of the developmental polarity of regenerating protoplasts isolated from prothallial cells of the fern Ceratopteris richardii (United States)

    Edwards, E. S.; Roux, S. J.


    A procedure has been developed for isolating protoplasts from prothalli of Ceratopteris richardii which can be cultured and are capable of regeneration. Protoplasts were isolated from 2-week-old gametophytes in a medium containing wall-digesting enzymes in 0.5 M sucrose, followed by purification of the released protoplasts by floating them up into a 0.5 M sorbitol layer. Regeneration occurred over a period of 10-24 days, and, under optimal osmotic conditions, followed the developmental pattern seen during spore germination, in that the first division gave rise to a primary rhizoid. Thus, prothallial protoplasts are comparable to germinating spores as suitable models for studies of developmental polarity in single cells. As in germinating spores, the polarity of development in regenerating protoplasts is influenced by the vectors of gravity and unilateral light. However, the relative influence of light in fixing this polarity is greater in regenerating protoplasts, while in germinating spores, the influence of gravity is greater.

  13. In Vitro Polarized Resonance Raman Study of N719 and N719-TBP in Dye Sensitized Solar Cells

    DEFF Research Database (Denmark)

    Hassing, Søren; Jernshøj, Kit Drescher; Nguyen, Phuong Tuyet;


    the adsorption of the dye on TiO2 can be obtained. Furthermore it is found that the polarization fluorescence anisotropy is very different for adsorbed and non-adsorbed dye molecules. This information is automatically obtained when processing the Raman data. The conclusion is that if the polarization properties......Abstract: The working efficiency of dye-sensitized solar cells (DSCs) depends on the long-term stability of the dye itself and on the microscopic structure of the dye-semiconductor interface. Previous experimental studies of DSCs based on ruthenium dye with bipyridine ligands (N719) adsorbed...... on N719/TiO2 – DSCs that by combining an analysis of the wave number dependent polarization of these modes with the small shifts observed in the visible absorption spectra of adsorbed, non-adsorbed molecules and degradation products new and more reliable information about dye stability and about...

  14. Prickle and Strabismus form a functional complex to generate a correct axis during planar cell polarity signaling. (United States)

    Jenny, Andreas; Darken, Rachel S; Wilson, Paul A; Mlodzik, Marek


    Frizzled (Fz) signaling regulates the establishment of planar cell polarity (PCP). The PCP genes prickle (pk) and strabismus (stbm) are thought to antagonize Fz signaling. We show that they act in the same cell, R4, adjacent to that in which the Fz/PCP pathway is required in the Drosophila eye. We demonstrate that Stbm and Pk interact physically and that Stbm recruits Pk to the cell membrane. Through this interaction, Pk affects Stbm membrane localization and can cause clustering of Stbm. Pk is also known to interact with Dsh and is thought to antagonize Dsh by affecting its membrane localization. Thus our data suggest that the Stbm/Pk complex modulates Fz/Dsh activity, resulting in a symmetry-breaking step during polarity signaling.

  15. Modulation of Endocytic Traffic in Polarized Madin-Darby Canine Kidney Cells by the Small GTPase RhoA (United States)

    Leung, Som-Ming; Rojas, Raul; Maples, Christopher; Flynn, Christopher; Ruiz, Wily G.; Jou, Tzuu-Shuh; Apodaca, Gerard


    Efficient postendocytic membrane traffic in polarized epithelial cells is thought to be regulated in part by the actin cytoskeleton. RhoA modulates assemblies of actin in the cell, and it has been shown to regulate pinocytosis and phagocytosis; however, its effects on postendocytic traffic are largely unexplored. To this end, we expressed wild-type RhoA (RhoAWT), dominant active RhoA (RhoAV14), and dominant inactive RhoA (RhoAN19) in Madin-Darby canine kidney (MDCK) cells expressing the polymeric immunoglobulin receptor. RhoAV14 expression stimulated the rate of apical and basolateral endocytosis, whereas RhoAN19 expression decreased the rate from both membrane domains. Polarized basolateral recycling of transferrin was disrupted in RhoAV14-expressing cells as a result of increased ligand release at the apical pole of the cell. Degradation of basolaterally internalized epidermal growth factor was slowed in RhoAV14-expressing cells. Although apical recycling of immunoglobulin A (IgA) was largely unaffected in cells expressing RhoAV14, transcytosis of basolaterally internalized IgA was severely impaired. Morphological and biochemical analyses demonstrated that a large proportion of IgA internalized from the basolateral pole of RhoAV14-expressing cells remained within basolateral early endosomes and was slow to exit these compartments. RhoAN19 and RhoAWT expression had little effect on these postendocytic pathways. These results indicate that in polarized MDCK cells activated RhoA may modulate endocytosis from both membrane domains and postendocytic traffic at the basolateral pole of the cell. PMID:10588664

  16. The adhesion GPCR latrophilin - a novel signaling cascade in oriented cell division and anterior-posterior polarity. (United States)

    Winkler, Jana; Prömel, Simone


    Although several signaling pathways in oriented cell division have been well characterized such as delta/notch inductions or wnt/frizzled-based anterior-posterior polarity, there is strong evidence for additional signal pathways controlling early anterior-posterior polarity decisions. The homolog of the adhesion G protein-coupled receptor latrophilin, LAT-1 has been identified as a receptor essential for oriented cell division in an anterior-posterior direction of specific blastomeres in the early C. elegans embryo. We recently conducted a study aiming at clarifying the signals involved in LAT-1 function. We identified a Gs protein/adenylyl cyclase/cAMP pathway in vitro and demonstrated its physiological relevance in oriented cell division. By interaction with a Gs protein LAT-1 elevates cAMP levels. These data indicate that G-protein signaling in oriented cell division is not solely GPCR-independent. This commentary will discuss our findings in the context of the current knowledge of mechanisms controlling oriented cell division and anterior-posterior polarity. Further, we identify open questions which need to be addressed in the future.

  17. Comparision between Ga- and N-polarity InGaN solar cells with gradient-In-composition intrinsic layers (United States)

    Lu, Lin; Li, Ming-Chao; Lv, Chen; Gao, Wen-Gen; Jiang, Ming; Xu, Fu-Jun; Chen, Qi-Gong


    Performances of Ga- and N-polarity solar cells (SCs) adopting gradient-In-composition intrinsic layer (IL) are compared. It is found the gradient ILs can greatly weaken the negative influence from the polarization effects for the Ga- polarity case, and the highest conversion efficiency (η) of 2.18% can be obtained in the structure with a linear increase of In composition in the IL from bottom to top. This is mainly attributed to the adsorptions of more photons caused by the higher In composition in the IL closer to the p-GaN window layer. In contrast, for the N-polarity case, the SC structure with an InGaN IL adopting fixed In composition prevails over the ones adopting the gradient-In-composition IL, where the highest η of 9.28% can be obtained at x of 0.62. N-polarity SC structures are proven to have greater potential preparations in high-efficient InGaN SCs. Project supported by the National Natural Science Foundation of China (Grant Nos. 61306108, 61172131, and 61271377), the Scientific Research Foundation for the Returned Overseas Chinese Scholars, Ministry of Education of China (Grant No. 2013693), and the Anhui Polytechnic University Funds for Excellent Young Scientists, China (Grant No. 2014YQQ005).

  18. Wnt/planar cell polarity signaling controls the anterior-posterior organization of monoaminergic axons in the brainstem. (United States)

    Fenstermaker, Ali G; Prasad, Asheeta A; Bechara, Ahmad; Adolfs, Youri; Tissir, Fadel; Goffinet, Andre; Zou, Yimin; Pasterkamp, R Jeroen


    Monoaminergic neurons [serotonergic (5-HT) and dopaminergic (mdDA)] in the brainstem project axons along the anterior-posterior axis. Despite their important physiological functions and implication in disease, the molecular mechanisms that dictate the formation of these projections along the anterior-posterior axis remain unknown. Here we reveal a novel requirement for Wnt/planar cell polarity signaling in the anterior-posterior organization of the monoaminergic system. We find that 5-HT and mdDA axons express the core planar cell polarity components Frizzled3, Celsr3, and Vangl2. In addition, monoaminergic projections show anterior-posterior guidance defects in Frizzled3, Celsr3, and Vangl2 mutant mice. The only known ligands for planar cell polarity signaling are Wnt proteins. In culture, Wnt5a attracts 5-HT but repels mdDA axons, and Wnt7b attracts mdDA axons. However, mdDA axons from Frizzled3 mutant mice are unresponsive to Wnt5a and Wnt7b. Both Wnts are expressed in gradients along the anterior-posterior axis, consistent with their role as directional cues. Finally, Wnt5a mutants show transient anterior-posterior guidance defects in mdDA projections. Furthermore, we observe during development that the cell bodies of migrating descending 5-HT neurons eventually reorient along the direction of their axons. In Frizzled3 mutants, many 5-HT and mdDA neuron cell bodies are oriented abnormally along the direction of their aberrant axon projections. Overall, our data suggest that Wnt/planar cell polarity signaling may be a global anterior-posterior guidance mechanism that controls axonal and cellular organization beyond the spinal cord.

  19. Mutations in planar cell polarity gene SCRIB are associated with spina bifida.

    Directory of Open Access Journals (Sweden)

    Yunping Lei

    Full Text Available Neural tube defects (NTDs (OMIM #182940 including anencephaly, spina bifida and craniorachischisis, are severe congenital malformations that affect 0.5-1 in 1,000 live births in the United States, with varying prevalence around the world. Mutations in planar cell polarity (PCP genes are believed to cause a variety of NTDs in both mice and humans. SCRIB is a PCP-associated gene. Mice that are homozygous for the Scrib p.I285K and circletail (Crc mutations, present with the most severe form of NTDs, namely craniorachischisis. A recent study reported that mutations in SCRIB were associated with craniorachischisis in humans, but whether SCRIB mutations contribute to increased spina bifida risk is still unknown. We sequenced the SCRIB gene in 192 infants with spina bifida and 190 healthy controls. Among the spina bifida patients, we identified five novel missense mutations that were predicted-to-be-deleterious by the PolyPhen software. Of these five mutations, three of them (p.P1043L, p.P1332L, p.L1520R significantly affected the subcellular localization of SCRIB. In addition, we demonstrated that the craniorachischisis mouse line-90 mutation I285K, also affected SCRIB subcellular localization. In contrast, only one novel missense mutation (p.A1257T was detected in control samples, and it was predicted to be benign. This study demonstrated that rare deleterious mutations of SCRIB may contribute to the multifactorial risk for human spina bifida.

  20. Keeping Noise Down on the Farm (United States)

    ... Do > Keeping Noise Down on the Farm Keeping Noise Down on the Farm SHARE Some people may ... risks permanent hearing damage. Take steps to reduce noise from machinery. Keep machinery running smoothly by replacing ...

  1. Study of Collagen Birefringence in Different Grades of Oral Squamous Cell Carcinoma Using Picrosirius Red and Polarized Light Microscopy

    Directory of Open Access Journals (Sweden)

    Pillai Arun Gopinathan


    Full Text Available Objectives. The present study was done to evaluate birefringence pattern of collagen fibres in different grades of oral squamous cell carcinoma using Picrosirius red stain and polarization microscopy and to determine if there is a change in collagen fibres between different grades of oral squamous cell carcinoma. Materials and Methods. Picrosirius red stained 5 μm thick sections of previously diagnosed different grades of squamous cell carcinoma and normal oral mucosa were studied under polarization microscopy for arrangement as well as birefringence of collagen fibres around tumour islands. Results. It was found that thin collagen fibres increased and thick collagen fibres decreased with dedifferentiation of OSCC (P<0.0001 . It was observed that there was change in polarization colours of thick fibres from yellowish orange to greenish yellow with dedifferentiation of OSCC indicating loosely packed fibres (P<0.0001. Conclusion. There was a gradual change of birefringence of collagen from yellowish orange to greenish yellow from well to poorly differentiated squamous cell carcinoma, indicating that there is a change from mature form of collagen to immature form as tumour progresses. Studying collagen fibres with Picrosirius red for stromal changes around tumour islands along with routine staining may help in predicting the prognosis of tumour.

  2. Metasurface polarization splitter

    CERN Document Server

    Slovick, Brian A; Yu, Zhi Gang; Kravchenckou, Ivan I; Briggs, Dayrl P; Moitra, Parikshit; Krishnamurthy, Srini; Valentine, Jason


    Polarization beam splitters, devices that separate the two orthogonal polarizations of light into different propagation directions, are one of the most ubiquitous optical elements. However, traditionally polarization splitters rely on bulky optical materials, while emerging optoelectronic and photonic circuits require compact, chip-scale polarization splitters. Here we show that a subwavelength rectangular lattice of cylindrical silicon Mie resonators functions as a polarization splitter, efficiently reflecting one polarization while transmitting the other. We show that the polarization splitting arises from the anisotropic permittivity and permeability of the metasurface due to the two-fold rotational symmetry of the rectangular unit cell. The high polarization efficiency, low loss, and low profile make these metasurface polarization splitters ideally suited for monolithic integration with optoelectronic and photonic circuits.

  3. Blazed vector grating liquid crystal cells with photocrosslinkable polymeric alignment films fabricated by one-step polarizer rotation method (United States)

    Kawai, Kotaro; Kuzuwata, Mitsuru; Sasaki, Tomoyuki; Noda, Kohei; Kawatsuki, Nobuhiro; Ono, Hiroshi


    Blazed vector grating liquid crystal (LC) cells, in which the directors of low-molar-mass LCs are antisymmetrically distributed, were fabricated by one-step exposure of an empty glass cell inner-coated with a photocrosslinkable polymer LC (PCLC) to UV light. By adopting a LC cell structure, twisted nematic (TN) and homogeneous (HOMO) alignments were obtained in the blazed vector grating LC cells. Moreover, the diffraction efficiency of the blazed vector grating LC cells was greatly improved by increasing the thickness of the device in comparison with that of a blazed vector grating with a thin film structure obtained in our previous study. In addition, the diffraction efficiency and polarization states of ±1st-order diffracted beams from the resultant blazed vector grating LC cells were controlled by designing a blazed pattern in the alignment films, and these diffraction properties were well explained on the basis of Jones calculus and the elastic continuum theory of nematic LCs.

  4. A dynamic complex of signaling proteins uses polar localization to regulate cell-fate asymmetry in Caulobacter crescentus. (United States)

    Tsokos, Christos G; Perchuk, Barrett S; Laub, Michael T


    Cellular asymmetry is critical to metazoan development and the life cycle of many microbes. In Caulobacter, cell cycle progression and the formation of asymmetric daughter cells depend on the polarly-localized histidine kinase CckA. How CckA is regulated and why activity depends on localization are unknown. Here, we demonstrate that the unorthodox kinase DivL promotes CckA activity and that the phosphorylated regulator DivK inhibits CckA by binding to DivL. Early in the cell cycle, CckA is activated by the dephosphorylation of DivK throughout the cell. However, in later stages, when phosphorylated DivK levels are high, CckA activation relies on polar localization with a DivK phosphatase. Localization thus creates a protected zone for CckA within the cell, without the use of membrane-enclosed compartments. Our results reveal the mechanisms by which CckA is regulated in a cell-type-dependent manner. More generally, our findings reveal how cells exploit subcellular localization to orchestrate sophisticated regulatory processes.

  5. Yeast Endocytic Adaptor AP-2 Binds the Stress Sensor Mid2 and Functions in Polarized Cell Responses (United States)

    Chapa-y-Lazo, Bernardo; Allwood, Ellen G; Smaczynska-de Rooij, Iwona I; Snape, Mary L; Ayscough, Kathryn R


    The AP-2 complex is a heterotetrameric endocytic cargo-binding adaptor that facilitates uptake of membrane proteins during mammalian clathrin-mediated endocytosis. While budding yeast has clear homologues of all four AP-2 subunits which form a complex and localize to endocytic sites in vivo, the function of yeast AP-2 has remained enigmatic. Here, we demonstrate that AP-2 is required for hyphal growth in Candida albicans and polarized cell responses in Saccharomyces cerevisiae. Deletion of APM4, the cargo-binding mu subunit of AP-2, causes defects in pseudohyphal growth, generation of a mating projection and the cell wall damage response. In an apm4 null mutant, the cell wall stress sensor Mid2 is unable to relocalize to the tip of a mating projection following pheromone addition, or to the mother bud neck in response to cell wall damage. A direct binding interaction between Mid2 and the mu homology domain of Apm4 further supports a model in which AP-2 binds Mid2 to facilitate its internalization and relocalization in response to specific signals. Thus, Mid2 is the first cargo for AP-2 identified in yeast. We propose that endocytic recycling of Mid2 and other components is required for polarized cell responses ensuring cell wall deposition and is tightly monitored during cell growth. PMID:24460703

  6. Sds22, a PP1 phosphatase regulatory subunit, regulates epithelial cell polarity and shape [Sds22 in epithelial morphology

    Directory of Open Access Journals (Sweden)

    Sung Hsin-Ho


    Full Text Available Abstract Background How epithelial cells adopt their particular polarised forms is poorly understood. In a screen for genes regulating epithelial morphology in Drosophila, we identified sds22, a conserved gene previously characterised in yeast. Results In the columnar epithelia of imaginal discs or follicle cells, mutation of sds22 causes contraction of cells along their apical-basal axis, resulting in a more cuboidal morphology. In addition, the mutant cells can also display altered cell polarity, forming multiple layers in follicle cells and leaving the epithelium in imaginal discs. In yeast, sds22 encodes a PP1 phosphatase regulatory subunit. Consistent with this, we show that Drosophila Sds22 binds to all four Drosophila PP1s and shares an overlapping phenotype with PP1beta9c. We also show that two previously postulated PP1 targets, Spaghetti Squash and Moesin are hyper-phosphorylated in sds22 mutants. This function is shared by the human homologue of Sds22, PPP1R7. Conclusion Sds22 is a conserved PP1 phosphatase regulatory subunit that controls cell shape and polarity.

  7. Record keeping, genetic selection, educational experience and farm management effects on average milk yield per cow, milk fat percentage, bacterial score and bulk tank somatic cell count of dairy farms in the Central region of Thailand. (United States)

    Rhone, J A; Koonawootrittriron, S; Elzo, M A


    A study was conducted to estimate the record keeping, genetic selection, educational, and farm management effects on average milk yield per cow (AYC), milk fat percentage, bacterial score, and bulk tank somatic cell count (BTSCC) of dairy farms in the central region of Thailand. Farms were located in the provinces of Saraburi and Nakhon Ratchisima and were members of the Muaklek dairy cooperative. Records from individual animals were unavailable. Thus, farm records of milk yield, milk fat percentage, bacterial score, and BTCCC were collected from July 1, 2003 through June 30, 2006. Additional record keeping, genetic selection, education, and farm management information was collected through a questionnaire in May of 2006. Data from the Muaklek dairy cooperative and the questionnaire were then merged by a farm identification number. A single trait mixed model was used to analyze AYC, milk fat percentage, and BTSCC, while a log linear model was used to analyze bacterial score. Results showed that farms that kept records on individual animals had higher (P personal opinion. Farms milking cows with a single unit milking machine and by hand, had higher (P < 0.05) bacterial scores and BTSCC than farms using only a single or multi unit machine. Overall farms that kept individual animal records, used EBV when selecting sires, used a single method for collecting milk, and used family labor achieved higher performance from their herds than farms that did not.

  8. Van Gogh-like2 (Strabismus) and its role in planar cell polarity and convergent extension in vertebrates. (United States)

    Torban, Elena; Kor, Christine; Gros, Philippe


    In the past two years, studies of Stbm genes (also known as Vangl2) and the proteins that they encode in mice, flies, frogs and fish have shown that they have a crucial role in regulating planar cell polarity and convergent extension movements. Combined genetic and biochemical analyses have pointed to signaling pathways where Stbm (Vangl2) proteins might act, and have identified several interacting proteins that form a crucial multi-protein signaling complex at the membrane. These studies show that these proteins have a pivotal role in a signaling cascade(s) that has been highly conserved in evolution. This review will summarize recent findings documenting the involvement of Stbm (Vangl2) and associated proteins in planar cell polarity, non-canonical Wnt signaling and convergent extension movements.

  9. Remodeling of the Fission Yeast Cdc42 Cell-Polarity Module via the Sty1 p38 Stress-Activated Protein Kinase Pathway. (United States)

    Mutavchiev, Delyan R; Leda, Marcin; Sawin, Kenneth E


    The Rho family GTPase Cdc42 is a key regulator of eukaryotic cellular organization and cell polarity [1]. In the fission yeast Schizosaccharomyces pombe, active Cdc42 and associated effectors and regulators (the "Cdc42 polarity module") coordinate polarized growth at cell tips by controlling the actin cytoskeleton and exocytosis [2-4]. Localization of the Cdc42 polarity module to cell tips is thus critical for its function. Here we show that the fission yeast stress-activated protein kinase Sty1, a homolog of mammalian p38 MAP kinase, regulates localization of the Cdc42 polarity module. In wild-type cells, treatment with latrunculin A, a drug that leads to actin depolymerization, induces dispersal of the Cdc42 module from cell tips and cessation of polarized growth [5, 6]. We show that latrunculin A treatment also activates the Sty1 MAP kinase pathway and, strikingly, we find that loss of Sty1 MAP kinase signaling prevents latrunculin A-induced dispersal of the Cdc42 module, allowing polarized growth even in complete absence of the actin cytoskeleton. Regulation of the Cdc42 module by Sty1 is independent of Sty1's role in stress-induced gene expression. We also describe a system for activation of Sty1 kinase "on demand" in the absence of any external stress, and use this to show that Sty1 activation alone is sufficient to disperse the Cdc42 module from cell tips in otherwise unperturbed cells. During nitrogen-starvation-induced quiescence, inhibition of Sty1 converts non-growing, depolarized cells into growing, polarized cells. Our results place MAP kinase Sty1 as an important physiological regulator of the Cdc42 polarity module.

  10. The Cyclase-associated Protein CAP as Regulator of Cell Polarity and cAMP Signaling in Dictyostelium


    Noegel, Angelika A; Blau-Wasser, Rosemarie; Sultana, Hameeda; Müller, Rolf; Israel, Lars; Schleicher, Michael; Patel, Hitesh; Weijer, Cornelis J


    Cyclase-associated protein (CAP) is an evolutionarily conserved regulator of the G-actin/F-actin ratio and, in yeast, is involved in regulating the adenylyl cyclase activity. We show that cell polarization, F-actin organization, and phototaxis are altered in a Dictyostelium CAP knockout mutant. Furthermore, in complementation assays we determined the roles of the individual domains in signaling and regulation of the actin cytoskeleton. We studied in detail the adenylyl cyclase activity and fo...

  11. Polarization Imaging Apparatus for Cell and Tissue Imaging and Diagnostics Project (United States)

    National Aeronautics and Space Administration — In recent years there has been an increasing interest in the propagation of polarized light in randomly scattering media. The investigation of backscattered light is...

  12. Polarization Imaging Apparatus for Cell and Tissue Imaging and Diagnostics Project (United States)

    National Aeronautics and Space Administration — This work proposes to capitalize on our Phase I success in a novel visible-near infrared Stokes polarization imaging technology based on high performance fast...

  13. Genetic interactions between planar cell polarity genes cause diverse neural tube defects in mice

    Directory of Open Access Journals (Sweden)

    Jennifer N. Murdoch


    Full Text Available Neural tube defects (NTDs are among the commonest and most severe forms of developmental defect, characterized by disruption of the early embryonic events of central nervous system formation. NTDs have long been known to exhibit a strong genetic dependence, yet the identity of the genetic determinants remains largely undiscovered. Initiation of neural tube closure is disrupted in mice homozygous for mutations in planar cell polarity (PCP pathway genes, providing a strong link between NTDs and PCP signaling. Recently, missense gene variants have been identified in PCP genes in humans with NTDs, although the range of phenotypes is greater than in the mouse mutants. In addition, the sequence variants detected in affected humans are heterozygous, and can often be detected in unaffected individuals. It has been suggested that interactions between multiple heterozygous gene mutations cause the NTDs in humans. To determine the phenotypes produced in double heterozygotes, we bred mice with all three pairwise combinations of Vangl2Lp, ScribCrc and Celsr1Crsh mutations, the most intensively studied PCP mutants. The majority of double-mutant embryos had open NTDs, with the range of phenotypes including anencephaly and spina bifida, therefore reflecting the defects observed in humans. Strikingly, even on a uniform genetic background, variability in the penetrance and severity of the mutant phenotypes was observed between the different double-heterozygote combinations. Phenotypically, Celsr1Crsh;Vangl2Lp;ScribCrc triply heterozygous mutants were no more severe than doubly heterozygous or singly homozygous mutants. We propose that some of the variation between double-mutant phenotypes could be attributed to the nature of the protein disruption in each allele: whereas ScribCrc is a null mutant and produces no Scrib protein, Celsr1Crsh and Vangl2Lp homozygotes both express mutant proteins, consistent with dominant effects. The variable outcomes of these genetic

  14. Genetic interactions between planar cell polarity genes cause diverse neural tube defects in mice. (United States)

    Murdoch, Jennifer N; Damrau, Christine; Paudyal, Anju; Bogani, Debora; Wells, Sara; Greene, Nicholas D E; Stanier, Philip; Copp, Andrew J


    Neural tube defects (NTDs) are among the commonest and most severe forms of developmental defect, characterized by disruption of the early embryonic events of central nervous system formation. NTDs have long been known to exhibit a strong genetic dependence, yet the identity of the genetic determinants remains largely undiscovered. Initiation of neural tube closure is disrupted in mice homozygous for mutations in planar cell polarity (PCP) pathway genes, providing a strong link between NTDs and PCP signaling. Recently, missense gene variants have been identified in PCP genes in humans with NTDs, although the range of phenotypes is greater than in the mouse mutants. In addition, the sequence variants detected in affected humans are heterozygous, and can often be detected in unaffected individuals. It has been suggested that interactions between multiple heterozygous gene mutations cause the NTDs in humans. To determine the phenotypes produced in double heterozygotes, we bred mice with all three pairwise combinations of Vangl2(Lp), Scrib(Crc) and Celsr1(Crsh) mutations, the most intensively studied PCP mutants. The majority of double-mutant embryos had open NTDs, with the range of phenotypes including anencephaly and spina bifida, therefore reflecting the defects observed in humans. Strikingly, even on a uniform genetic background, variability in the penetrance and severity of the mutant phenotypes was observed between the different double-heterozygote combinations. Phenotypically, Celsr1(Crsh);Vangl2(Lp);Scrib(Crc) triply heterozygous mutants were no more severe than doubly heterozygous or singly homozygous mutants. We propose that some of the variation between double-mutant phenotypes could be attributed to the nature of the protein disruption in each allele: whereas Scrib(Crc) is a null mutant and produces no Scrib protein, Celsr1(Crsh) and Vangl2(Lp) homozygotes both express mutant proteins, consistent with dominant effects. The variable outcomes of these genetic

  15. A family of ROP proteins that suppresses actin dynamics, and is essential for polarized growth and cell adhesion. (United States)

    Burkart, Graham M; Baskin, Tobias I; Bezanilla, Magdalena


    In plants, the ROP family of small GTPases has been implicated in the polarized growth of tip-growing cells, such as root hairs and pollen tubes; however, most of the data derive from overexpressing ROP genes or constitutively active and dominant-negative isoforms, whereas confirmation by using loss-of-function studies has generally been lacking. Here, in the model moss Physcomitrella patens, we study ROP signaling during tip growth by using a loss-of-function approach based on RNA interference (RNAi) to silence the entire moss ROP family. We find that plants with reduced expression of ROP genes, in addition to failing to initiate tip growth, have perturbed cell wall staining, reduced cell adhesion and have increased actin-filament dynamics. Although plants subjected to RNAi against the ROP family also have reduced microtubule dynamics, this reduction is not specific to loss of ROP genes, as it occurs when actin function is compromised chemically or genetically. Our data suggest that ROP proteins polarize the actin cytoskeleton by suppressing actin-filament dynamics, leading to an increase in actin filaments at the site of polarized secretion.

  16. DC electric fields direct breast cancer cell migration, induce EGFR polarization, and increase the intracellular level of calcium ions. (United States)

    Wu, Dan; Ma, Xiuli; Lin, Francis


    Migration of cancer cells leads to invasion of primary tumors to distant organs (i.e., metastasis). Growing number of studies have demonstrated the migration of various cancer cell types directed by applied direct current electric fields (dcEF), i.e., electrotaxis, and suggested its potential implications in metastasis. MDA-MB-231 cell, a human metastatic breast cancer cell line, has been shown to migrate toward the anode of dcEF. Further characterizations of MDA-MB-231 cell electrotaxis and investigation of its underlying signaling mechanisms will lead to a better understanding of electrically guided cancer cell migration and metastasis. Therefore, we quantitatively characterized MDA-MB-231 cell electrotaxis and a few associated signaling events. Using a microfluidic device that can create well-controlled dcEF, we showed the anode-directing migration of MDA-MB-231 cells. In addition, surface staining of epidermal growth factor receptor (EGFR) and confocal microscopy showed the dcEF-induced anodal EGFR polarization in MDA-MB-231 cells. Furthermore, we showed an increase of intracellular calcium ions in MDA-MB-231 cells upon dcEF stimulation. Altogether, our study provided quantitative measurements of electrotactic migration of MDA-MB-231 cells, and demonstrated the electric field-mediated EGFR and calcium signaling events, suggesting their involvement in breast cancer cell electrotaxis.

  17. Activation and polar sequestration of PopA, a c-di-GMP effector protein involved in Caulobacter crescentus cell cycle control

    DEFF Research Database (Denmark)

    Ozaki, Shogo; Schalch-Moser, Annina; Zumthor, Ludwig;


    When Caulobacter crescentus enters S-phase the replication initiation inhibitor CtrA dynamically positions to the old cell pole to be degraded by the polar ClpXP protease. Polar delivery of CtrA requires PopA and the diguanylate cyclase PleD that positions to the same pole. Here we present evidence...

  18. Effect of modulation of PPAR-γ activity on Kupffer cells M1/M2 polarization in the development of non-alcoholic fatty liver disease (United States)

    Luo, Wenjing; Xu, Qinyu; Wang, Qi; Wu, Huimin; Hua, Jing


    Abnormal lipid-mediated hepatic inflammatory-immune dysfunction and chronic low grade inflammation play an important role in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). Macrophage polarization is an important mechanism for the regulation of inflammatory response. Since PPAR-γ has emerged as a master regulator of macrophage polarization, we aimed to investigate the lipid-induced macrophage/Kupffer cell polarization in vivo and in vitro, and explore the association between PPAR-γ activity and macrophages M1/M2 polarization shifting. Here we showed that long-term high-fat diet increased Kupffer cells content with M1-predominant phenotype and increasing production of pro-inflammatory cytokines. Saturated fatty acids polarized Kupffer cells/macrophages to an M1-predominant phenotype while n-3 PUFA polarized Kupffer cells/macrophages to an M2 phenotype, which was associated with activation of NF-κB signal pathway and PPAR-γ respectively. Furthermore, up-regulation of PPAR-γ shifted lipid-induced macrophages polarization from M1-predominant phenotype to M2 phenotype. Macrophages polarization switch was associated with the interaction between PPAR-γ and NF-κBp65 signal pathway. Rosiglitazone restored high-fat diet-induced imblance of Kupffer cells M1/M2 polarization and alleviated hepatic steatosis as well as local pro-inflammatory response. These findings suggest that manipulation of PPAR-γ activity has the potential to balance lipid-induced M1/M2 macrophage/Kupffer cell polarization, and leading to prevent the development of NAFLD. PMID:28300213

  19. Mammalian diaphanous-related formin 1 regulates GSK3β-dependent microtubule dynamics required for T cell migratory polarization.

    Directory of Open Access Journals (Sweden)

    Baoxia Dong

    Full Text Available The mammalian diaphanous-related formin (mDia1, a Rho-regulated cytoskeletal modulator, has been shown to promote T lymphocyte chemotaxis and interaction with antigen presenting cells, but the mechanisms underpinning mDia1 roles in these processes have not been defined. Here we show that mDia1(-/- T cells exhibit impaired lymphocyte function-associated antigen 1 (LFA-1-mediated T cell adhesion, migration and in vivo trafficking. These defects are associated with impaired microtubule (MT polarization and stabilization, altered MT dynamics and reduced peripheral clustering of the MT plus-end-protein, adenomatous polyposis coli (APC in migrating T cells following LFA-1-engagement. Loss of mDia1 also leads to impaired inducible inactivation of the glycogen synthase kinase (GSK 3β as well as hyperphosphorylation and reduced levels of APC in migrating T cells. These findings identify essential roles for the mDia1 formin in modulating GSK3β-dependent MT contributions to induction of T-cell polarity, adhesion and motility.

  20. Mammalian diaphanous-related formin 1 regulates GSK3β-dependent microtubule dynamics required for T cell migratory polarization. (United States)

    Dong, Baoxia; Zhang, Steven S; Gao, Wen; Su, Haichun; Chen, Jun; Jin, Fuzi; Bhargava, Ajay; Chen, Xiequn; Jorgensen, Lars; Alberts, Arthur S; Zhang, Jinyi; Siminovitch, Katherine A


    The mammalian diaphanous-related formin (mDia1), a Rho-regulated cytoskeletal modulator, has been shown to promote T lymphocyte chemotaxis and interaction with antigen presenting cells, but the mechanisms underpinning mDia1 roles in these processes have not been defined. Here we show that mDia1(-/-) T cells exhibit impaired lymphocyte function-associated antigen 1 (LFA-1)-mediated T cell adhesion, migration and in vivo trafficking. These defects are associated with impaired microtubule (MT) polarization and stabilization, altered MT dynamics and reduced peripheral clustering of the MT plus-end-protein, adenomatous polyposis coli (APC) in migrating T cells following LFA-1-engagement. Loss of mDia1 also leads to impaired inducible inactivation of the glycogen synthase kinase (GSK) 3β as well as hyperphosphorylation and reduced levels of APC in migrating T cells. These findings identify essential roles for the mDia1 formin in modulating GSK3β-dependent MT contributions to induction of T-cell polarity, adhesion and motility.

  1. Wdpcp, a PCP protein required for ciliogenesis, regulates directional cell migration and cell polarity by direct modulation of the actin cytoskeleton.

    Directory of Open Access Journals (Sweden)

    Cheng Cui


    Full Text Available Planar cell polarity (PCP regulates cell alignment required for collective cell movement during embryonic development. This requires PCP/PCP effector proteins, some of which also play essential roles in ciliogenesis, highlighting the long-standing question of the role of the cilium in PCP. Wdpcp, a PCP effector, was recently shown to regulate both ciliogenesis and collective cell movement, but the underlying mechanism is unknown. Here we show Wdpcp can regulate PCP by direct modulation of the actin cytoskeleton. These studies were made possible by recovery of a Wdpcp mutant mouse model. Wdpcp-deficient mice exhibit phenotypes reminiscent of Bardet-Biedl/Meckel-Gruber ciliopathy syndromes, including cardiac outflow tract and cochlea defects associated with PCP perturbation. We observed Wdpcp is localized to the transition zone, and in Wdpcp-deficient cells, Sept2, Nphp1, and Mks1 were lost from the transition zone, indicating Wdpcp is required for recruitment of proteins essential for ciliogenesis. Wdpcp is also found in the cytoplasm, where it is localized in the actin cytoskeleton and in focal adhesions. Wdpcp interacts with Sept2 and is colocalized with Sept2 in actin filaments, but in Wdpcp-deficient cells, Sept2 was lost from the actin cytoskeleton, suggesting Wdpcp is required for Sept2 recruitment to actin filaments. Significantly, organization of the actin filaments and focal contacts were markedly changed in Wdpcp-deficient cells. This was associated with decreased membrane ruffling, failure to establish cell polarity, and loss of directional cell migration. These results suggest the PCP defects in Wdpcp mutants are not caused by loss of cilia, but by direct disruption of the actin cytoskeleton. Consistent with this, Wdpcp mutant cochlea has normal kinocilia and yet exhibits PCP defects. Together, these findings provide the first evidence, to our knowledge, that a PCP component required for ciliogenesis can directly modulate the actin

  2. Extracellular enzymatic activities of cold-adapted bacteria from polar oceans and effect of temperature and salinity on cell growth

    Institute of Scientific and Technical Information of China (English)

    Zeng Yinxin; Yu Yong; Chen Bo; Li Huirong


    The potential of 324 bacteria isolated from different habitats in polar oceans to produce a variety of extracellular enzymatic activities at low temperature was investigated. By plate assay, lipase, protease, amylase, gelatinase, agarase, chitinase or cellulase were detected. Lipases were generally present by bacteria living in polar oceans. Protease-producing bacteria held the second highest proportion in culturable isolates. Strains producing amylase kept a relative stable proportion of around 30% in different polar marine habitats. All 50 Arctic sea-ice bacteria producing proteases were cold-adapted strains, however, only 20% were psychrophilic. 98% of them could grow at 3% NaCl, and 56% could grow without NaCl. On the other hand, 98% of these sea-ice bacteria produced extracellular proteases with optimum temperature at or higher than 35℃, well above the upper temperature limit of cell growth. Extracellular enzymes including amylase, agarase, cellulase and lipase released by bacteria from seawater or sediment in polar oceans, most expressed maximum activities between 25 and 35℃. Among extracellular enzymes released by bacterial strain BSw20308, protease expressed maximum activity at 40℃, higher than 35℃ of polysaccharide hydrolases and 25℃ of lipase.

  3. No evidence of altered alveolar macrophage polarization, but reduced expression of TLR2, in bronchoalveolar lavage cells in sarcoidosis

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    Wikén Maria


    Full Text Available Abstract Background Sarcoidosis is a granulomatous inflammatory disease, possibly of infectious aetiology. We aimed to investigate whether the degree of functional polarization of alveolar macrophages (AMs, or Toll-like receptor (TLR expression, is associated with sarcoidosis or with distinct clinical manifestations of this disease. Methods Total BAL cells (cultured four or 24 h in medium, or stimulated 24 h with LPS from 14 patients and six healthy subjects, sorted AMs from 22 patients (Löfgren's syndrome n = 11 and 11 healthy subjects, and sorted CD4+ T cells from 26 patients (Löfgren's syndrome n = 13 and seven healthy subjects, were included. Using real-time PCR, the relative gene expression of IL-10, IL-12p35, IL-12p40, IL-23p19, CCR2, CCR7, iNOS, CXCL10, CXCL11, CXCL16, CCL18, CCL20, CD80, and CD86, and innate immune receptors TLR2, TLR4, and TLR9, was quantified in sorted AMs, and for selected genes in total BAL cells, while IL-17A was quantified in T cells. Results We did not find evidence of a difference with regard to alveolar macrophage M1/M2 polarization between sarcoidosis patients and healthy controls. TLR2 gene expression was significantly lower in sorted AMs from patients, particular in Löfgren's patients. CCL18 gene expression in AMs was significantly higher in patients compared to controls. Additionally, the IL-17A expression was lower in Löfgren's patients' CD4+ T cells. Conclusions Overall, there was no evidence for alveolar macrophage polarization in sarcoidosis. However, there was a reduced TLR2 mRNA expression in patients with Löfgren's syndrome, which may be of relevance for macrophage interactions with a postulated sarcoidosis pathogen, and for the characteristics of the ensuing T cell response.

  4. Formation of Kv2.1-FAK Complex as a Mechanism of FAK Activation, Cell Polarization and Enhanced Motility


    Wei, Jian-Feng; Wei, Ling; ZHOU, XIN; Lu, Zhong-yang; Francis, Kevin; Hu, Xin-yang; Liu, Yu; Xiong, Wen-Cheng; Zhang, Xiao; Banik, Naren L.; Zheng, Shu-Sen; Yu, Shan Ping


    Focal adhesion kinase (FAK) plays key roles in cell adhesion and migration. We now report that the delayed rectifier Kv2.1 potassium channel, through its LD-like motif in N-terminus, may interact with FAK and enhance phosphorylation of FAK397 and FAK576/577. Overlapping distribution of Kv2.1 and FAK was observed on soma and proximal dendrites of cortical neurons. FAK expression promotes a polarized membrane distribution of the Kv2.1 channel. In Kv2.1-transfected CHO cells, formation of the Kv...

  5. Water-polysaccharide interactions in the primary cell wall of Arabidopsis thaliana from polarization transfer solid-state NMR. (United States)

    White, Paul B; Wang, Tuo; Park, Yong Bum; Cosgrove, Daniel J; Hong, Mei


    Polysaccharide-rich plant cell walls are hydrated under functional conditions, but the molecular interactions between water and polysaccharides in the wall have not been investigated. In this work, we employ polarization transfer solid-state NMR techniques to study the hydration of primary-wall polysaccharides of the model plant, Arabidopsis thaliana. By transferring water (1)H polarization to polysaccharides through distance- and mobility-dependent (1)H-(1)H dipolar couplings and detecting it through polysaccharide (13)C signals, we obtain information about water proximity to cellulose, hemicellulose, and pectins as well as water mobility. Both intact and partially extracted cell wall samples are studied. Our results show that water-pectin polarization transfer is much faster than water-cellulose polarization transfer in all samples, but the extent of extraction has a profound impact on the water-polysaccharide spin diffusion. Removal of calcium ions and the consequent extraction of homogalacturonan (HG) significantly slowed down spin diffusion, while further extraction of matrix polysaccharides restored the spin diffusion rate. These trends are observed in cell walls with similar water content, thus they reflect inherent differences in the mobility and spatial distribution of water. Combined with quantitative analysis of the polysaccharide contents, our results indicate that calcium ions and HG gelation increase the amount of bound water, which facilitates spin diffusion, while calcium removal disrupts the gel and gives rise to highly dynamic water, which slows down spin diffusion. The recovery of spin diffusion rates after more extensive extraction is attributed to increased water-exposed surface areas of the polysaccharides. Water-pectin spin diffusion precedes water-cellulose spin diffusion, lending support to the single-network model of plant primary walls in which a substantial fraction of the cellulose surface is surrounded by pectins.

  6. Localization of Core Planar Cell Polarity Proteins, PRICKLEs, in Ameloblasts of Rat Incisors: Possible Regulation of Enamel Rod Decussation. (United States)

    Nishikawa, Sumio; Kawamoto, Tadafumi


    To confirm the possible involvement of planar cell polarity proteins in odontogenesis, one group of core proteins, PRICKLE1, PRICKLE2, PRICKLE3, and PRICKLE4, was examined in enamel epithelial cells and ameloblasts by immunofluorescence microscopy. PRICKLE1 and PRICKLE2 showed similar localization in the proliferation and secretory zones of the incisor. Immunoreactive dots and short rods in ameloblasts and stratum intermedium cells were evident in the proliferation to differentiation zone, but in the secretion zone, cytoplasmic dots decreased and the distal terminal web was positive for PRICKLE1 and PRICKLE2. PRICKLE3 and PRICKLE4 showed cytoplasmic labeling in ameloblasts and other enamel epithelial cells. Double labeling of PRICKLE2 with VANGL1, which is another planar cell polarity protein, showed partial co-localization. To examine the transport route of PRICKLE proteins, PRICKLE1 localization was examined after injection of a microtubule-disrupting reagent, colchicine, and was compared with CX43, which is a membrane protein transported as vesicles via microtubules. The results confirmed the retention of immunoreactive dots for PRICKLE1 in the cytoplasm of secretory ameloblasts of colchicine-injected animals, but fewer dots were observed in control animals. These results suggest that PRICKLE1 and PRICKLE2 are transported as vesicles to the junctional area, and are involved in pattern formation of distal junctional complexes and terminal webs of ameloblasts, further implying a role in the formed enamel rod arrangement.

  7. Phosphorylation of the E3 ubiquitin ligase RNF41 by the kinase Par-1b is required for epithelial cell polarity. (United States)

    Lewandowski, Katherine T; Piwnica-Worms, Helen


    The establishment and maintenance of cell polarity is an essential property governing organismal homeostasis, and loss of polarity is a common feature of cancer cells. The ability of epithelial cells to establish apical-basal polarity depends on intracellular signals generated from polarity proteins, such as the Par-1 family of proteins, as well as extracellular signals generated through cell contacts with the extracellular matrix (ECM). The Par-1 family has a well-established role in regulating cell-cell contacts in the form of tight junctions by phosphorylating Par-3. In addition, Par-1 has been shown to impact on cell-ECM interactions by regulating laminin receptor localization and laminin deposition on the basal surface of epithelial cells. Laminins are major structural and signaling components of basement membrane (BM), a sheet of specialized ECM underlying epithelia. In this study, we identify RNF41, an E3 ubiquitin ligase, as a novel Par-1b (also known as MARK2) effector in the cell-ECM pathway. Par-1b binds to and phosphorylates RNF41 on serine 254. Phosphorylation of RNF41 by Par-1b is required for epithelial cells to localize laminin-111 receptors to their basolateral surfaces and to properly anchor to laminin-111. In addition, phosphorylation of RNF41 is required for epithelial cells to establish apical-basal polarity. Our data suggests that phosphorylation of RNF41 by Par-1b regulates basolateral membrane targeting of laminin-111 receptors, thereby facilitating cell anchorage to laminin-111 and ultimately forming the cell-ECM contacts required for epithelial cells to establish apical-basal cell polarity.

  8. A specific sorting signal is not required for the polarized secretion of newly synthesized proteins from cultured intestinal epithelial cells. (United States)

    Rindler, M J; Traber, M G


    Caco-2 cells, derived from human colon, have the morphological, functional, and biochemical properties of small intestinal epithelial cells. After infection with enveloped viruses, influenza virions assembled at the apical plasma membrane while vesicular stomatitis virus (VSV) particles appeared exclusively at the basolateral membrane, similar to the pattern observed in virus-infected Madin-Darby canine kidney (MDCK). When grown in Millicell filter chamber devices and labeled with [35S]methionine, Caco-2 monolayers released all of their radiolabeled secretory products preferentially into the basal chamber. Among the proteins identified were apolipoproteins AI and E, transferrin, and alpha-fetoprotein. No proteins were observed to be secreted preferentially from the apical cell surface. The lysosomal enzyme beta-hexosaminidase was also secreted primarily from the basolateral surface of the cells in the presence or absence of lysosomotropic drugs or tunicamycin, which inhibit the targetting of lysosomal enzymes to lysosomes. Neither of these drug treatments significantly affected the polarized secretion of other nonlysosomal proteins. In addition, growth hormone (GH), which is released in a nonpolar fashion from MDCK cells, was secreted exclusively from the basolateral membrane after transfection of Caco-2 cells with GH cDNA in a pSV2-based expression vector. Similar results were obtained in transient expression experiments and after selection of permanently transformed Caco-2 cells expressing GH. Since both beta-hexosaminidase and GH would be expected to lack sorting signals for polarized exocytosis in epithelial cells, these results indicate that in intestinal cells, proteins transported via the basolateral secretory pathway need not have specific sorting signals.

  9. Electrochemical Performance and Stability of the Cathode for Solid Oxide Fuel Cells. I. Cross Validation of Polarization Measurements by Impedance Spectroscopy and Current-Potential Sweep

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Xiao Dong; Pederson, Larry R.; Templeton, Jared W.; Stevenson, Jeffry W.


    The aim of this paper is to address three issues in solid oxide fuel cells: (1) cross-validation of the polarization of a single cell measured using both dc and ac approaches, (2) the precise determination of the total areal specific resistance (ASR), and (3) understanding cathode polarization with LSCF cathodes. The ASR of a solid oxide fuel cell is a dynamic property, meaning that it changes with current density. The ASR measured using ac impedance spectroscopy (low frequency interception with real Z´ axis of ac impedance spectrum) matches with that measured from a dc IV sweep (the tangent of dc i-V curve). Due to the dynamic nature of ASR, we found that an ac impedance spectrum measured under open circuit voltage or on a half cell may not represent cathode performance under real operating conditions, particularly at high current density. In this work, the electrode polarization was governed by the cathode activation polarization; the anode contribution was negligible.

  10. The fenestrin antigen in submembrane skeleton of the ciliate Tetrahymena thermophila is proposed as a marker of cell polarity during cell division and in oral replacement. (United States)

    Kaczanowska, Janina; Joachimiak, Ewa; Kiersnowska, Mauryla; Krzywicka, Anna; Golinska, Krystyna; Kaczanowski, Andrzej


    Tetrahymena thermophila cells have two types of polarized morphogenesis: divisional morphogenesis and oral reorganization (OR). The aim of this research is the analysis of cortical patterns of immunostaining during cell division and in OR using previously characterized antibodies against fenestrin and epiplasm B proteins. During cell division, the anarchic field of basal body proliferation of the new developing oral apparatus (AF) showed concomitant strong binding of the fenestrin antigen and withdrawal of a signal of the epiplasm B antigen. At a specific stage, the fenestrin antigen also appeared as a character of the anterior cortex pole, with a co-localized decrease in the detected epiplasm B antigen. The fenestrin antigen also showed a polarity of duplicating basal bodies in ciliary rows. Indirect immunofluorescence and immunogold labeling experiments were performed in the absence and presence of an inhibitor of activity of serine/threonine kinases, 6-dimethylaminopurine (6-DMAP) as an inducer of the oral replacement process. In the presence of 6-DMAP, one class of cells started OR, and some others were trapped and affected in cell division. Both types of cells showed an instability of oral structures and formed enlarged primordial oral fields. These anarchic fields (AFs) bind the fenestrin antigen, with disappearance of epiplasmic antigen staining. Only one protein (about 64 kDa) is detected in western blots by the anti-fenestrin antibody and it accumulated in 6-DMAP-treated cells that are involved in uncompleted morphogenetic activity. At a defined stage of oral development, both during cell division and in OR, the fenestrin antigen served as a marker of polarity of the cell of the anterior pole character.

  11. Polarization Analysis Equipment in SANS-J-II: Study of Polymer Electrolyte Membrane for Fuel Cell (United States)

    Noda, Yohei; Yamaguchi, Daisuke; Putra, Ananda; Koizumi, Satoshi; Sakaguchi, Yoshifumi; Oku, Takayuki; Suzuki, Jun-ichi

    In small angle neutron scattering spectrometer, SANS-J-II at Japan Research Reactor No. 3 (JRR-3), a polarization analysis setup has been equipped, which is composed of transmission-type supermirror polarizer, radial-bender-type supermirror analyzer, π flipper, and solenoids for generating guide magnetic field. This setup was applied to the structural study of polymer electrolyte membrane, Nafion under water-swollen state. The sample is known to exhibit several characteristic peaks at wide angle region, which is related to water transporting channels. By use of polarization analysis technique, the coherent and incoherent contributions were successfully separated. Consequently, we obtained reliable information about decaying power law of ionic cluster peak and the shape of the broad peak, relating to ordering with short distance (5.6 Å).

  12. Emerging role of cell polarity proteins in breast cancer progression and metastasis

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    Chatterjee SJ


    Full Text Available Sudipa June Chatterjee, Luke McCaffrey Rosalind and Morris Goodman Cancer Centre, Department of Oncology, McGill University, Montreal, QC, Canada Abstract: Breast cancer is a heterogeneous group of diseases that frequently exhibits loss of growth control, and disrupted tissue organization and differentiation. Several recent studies indicate that apical–basal polarity provides a tumor-suppressive function, and that disrupting polarity proteins affects many stages of breast cancer progression from initiation through metastasis. In this review we highlight some of the recent advances in our understanding of the molecular mechanisms by which loss of apical–basal polarity deregulates apoptosis, proliferation, and promotes invasion and metastasis in breast cancer. Keywords: apical, basal, oncogene, tumor suppressor, proliferation, apoptosis

  13. Polarization and Dielectric Study of Methylammonium Lead Iodide Thin Film to Reveal its Nonferroelectric Nature under Solar Cell Operating Conditions

    Energy Technology Data Exchange (ETDEWEB)

    Hoque, Md Nadim Ferdous; Yang, Mengjin; Li, Zhen; Islam, Nazifah; Pan, Xuan; Zhu, Kai; Fan, Zhaoyang


    Researchers have debated whether methylammonium lead iodide (MAPbI3), with a perovskite crystal structure, is ferroelectric and therefore contributes to the current--voltage hysteresis commonly observed in hybrid perovskite solar cells (PSCs). We thoroughly investigated temperature-dependent polarization, dielectric, and impedance spectroscopies, and we found no evidence of ferroelectric effect in a MAPbI3 thin film at normal operating conditions. Therefore, the effect does not contribute to the hysteresis in PSCs, whereas the large component of ionic migration observed may play a critical role. Our temperature-based polarization and dielectric studies find that MAPbI3 exhibits different electrical behaviors below and above ca. 45 degrees C, suggesting a phase transition around this temperature. In particular, we report the activation energies of ionic migration for the two phases and temperature-dependent permittivity of MAPbI3. This study contributes to the understanding of the material properties and device performance of hybrid perovskites.

  14. Planar cell polarity genes frizzled4 and frizzled6 exert patterning influence on arterial vessel morphogenesis (United States)

    Gosak, Marko; Horvat, Denis; Žalik, Borut; Seguy, Benjamin; Chauvel, Remi; Malandain, Gregoire; Couffinhal, Thierry; Duplàa, Cécile; Marhl, Marko


    Quantitative analysis of the vascular network anatomy is critical for the understanding of the vasculature structure and function. In this study, we have combined microcomputed tomography (microCT) and computational analysis to provide quantitative three-dimensional geometrical and topological characterization of the normal kidney vasculature, and to investigate how 2 core genes of the Wnt/planar cell polarity, Frizzled4 and Frizzled6, affect vascular network morphogenesis. Experiments were performed on frizzled4 (Fzd4-/-) and frizzled6 (Fzd6-/-) deleted mice and littermate controls (WT) perfused with a contrast medium after euthanasia and exsanguination. The kidneys were scanned with a high-resolution (16 μm) microCT imaging system, followed by 3D reconstruction of the arterial vasculature. Computational treatment includes decomposition of 3D networks based on Diameter-Defined Strahler Order (DDSO). We have calculated quantitative (i) Global scale parameters, such as the volume of the vasculature and its fractal dimension (ii) Structural parameters depending on the DDSO hierarchical levels such as hierarchical ordering, diameter, length and branching angles of the vessel segments, and (iii) Functional parameters such as estimated resistance to blood flow alongside the vascular tree and average density of terminal arterioles. In normal kidneys, fractal dimension was 2.07±0.11 (n = 7), and was significantly lower in Fzd4-/- (1.71±0.04; n = 4), and Fzd6-/- (1.54±0.09; n = 3) kidneys. The DDSO number was 5 in WT and Fzd4-/-, and only 4 in Fzd6-/-. Scaling characteristics such as diameter and length of vessel segments were altered in mutants, whereas bifurcation angles were not different from WT. Fzd4 and Fzd6 deletion increased vessel resistance, calculated using the Hagen-Poiseuille equation, for each DDSO, and decreased the density and the homogeneity of the distal vessel segments. Our results show that our methodology is suitable for 3D quantitative

  15. Molecular scaffolds underpinning macroglial polarization: an analysis of retinal Müller cells and brain astrocytes in mouse. (United States)

    Enger, Rune; Gundersen, Georg Andreas; Haj-Yasein, Nadia Nabil; Eilert-Olsen, Martine; Thoren, Anna Elisabeth; Vindedal, Gry Fluge; Petersen, Pétur Henry; Skare, Øivind; Nedergaard, Maiken; Ottersen, Ole Petter; Nagelhus, Erlend A


    Key roles of macroglia are inextricably coupled to specialized membrane domains. The perivascular endfoot membrane has drawn particular attention, as this domain contains a unique complement of aquaporin-4 (AQP4) and other channel proteins that distinguishes it from perisynaptic membranes. Recent studies indicate that the polarization of macroglia is lost in a number of diseases, including temporal lobe epilepsy and Alzheimer's disease. A better understanding is required of the molecular underpinning of astroglial polarization, particularly when it comes to the significance of the dystrophin associated protein complex (DAPC). Here, we employ immunofluorescence and immunogold cytochemistry to analyze the molecular scaffolding in perivascular endfeet in macroglia of retina and three regions of brain (cortex, dentate gyrus, and cerebellum), using AQP4 as a marker. Compared with brain astrocytes, Müller cells (a class of retinal macroglia) exhibit lower densities of the scaffold proteins dystrophin and α-syntrophin (a DAPC protein), but higher levels of AQP4. In agreement, depletion of dystrophin or α-syntrophin--while causing a dramatic loss of AQP4 from endfoot membranes of brain astrocytes--had only modest or insignificant effect, respectively, on the AQP4 pool in endfoot membranes of Müller cells. In addition, while polarization of brain macroglia was less affected by dystrophin depletion than by targeted deletion of α-syntrophin, the reverse was true for retinal macroglia. These data indicate that the molecular scaffolding in perivascular endfeet is more complex than previously assumed and that macroglia are heterogeneous with respect to the mechanisms that dictate their polarization.

  16. Architectural Analysis of Picrosirius Red Stained Collagen in Oral Epithelial Dysplasia and Oral Squamous Cell Carcinoma using Polarization Microscopy (United States)

    Sharma, Rashi; Rehani, Shweta; Mehendiratta, Monica; Kumra, Madhumani; Mathias, Yulia; Yadav, Jyoti; Sahay, Khushboo


    Introduction Collagen degradation is important both for carcinogenesis and in its progression. Research regarding the co-relation of collagen with Oral Epithelial Dysplasia (OED) and Oral Squamous Cell Carcinoma (OSCC) is less explored. Aim To elucidate the nature of collagen in Oral Epithelial Dysplasia (OED) and Oral Squamous Cell Carcinoma (OSCC) using Picrosirius Red Stain (PSR) under polarizing microscopy. Materials and Methods The study consisted of a total 40 samples which were divided into three groups. Group I included buccal mucosa as negative and irritation fibroma as positive control, group II consisted of OED and group III consisted of Oral Squamous Cell Carcinoma (OSCC). A histochemical analysis was conducted using PSR-polarization method by two independent observers. Results The control group shows predominantly reddish–orange birefringence. In OED with the advancement of grades, the colour changed from yellowish-orange colour to yellow-greenish with progressive increase in greenish hue. As OSCC regresses from well to poorly differentiated, the colour changed from reddish-orange to yellowish orange to greenish-yellow suggesting a transition from mature to immature collagen. Conclusion An observable gradual change in collagen of both OED and OSCC was noted as they were proceeding from benign to critical step. Thus, PSR is a useful tool for studying stromal changes as supporting collagen shows the transition in the form besides the alterations in epithelial cells. PMID:26816897

  17. Planar cell polarity: the Dachsous/Fat system contributes differently to the embryonic and larval stages of Drosophila. (United States)

    Saavedra, Pedro; Brittle, Amy; Palacios, Isabel M; Strutt, David; Casal, José; Lawrence, Peter A


    The epidermal patterns of all three larval instars (L1-L3) ofDrosophilaare made by one unchanging set of cells. The seven rows of cuticular denticles of all larval stages are consistently planar polarised, some pointing forwards, others backwards. In L1 all the predenticles originate at the back of the cells but, in L2 and L3, they form at the front or the back of the cell depending on the polarity of the forthcoming denticles. We find that, to polarise all rows, the Dachsous/Fat system is differentially utilised; in L1 it is active in the placement of the actin-based predenticles but is not crucial for the final orientation of the cuticular denticles, in L2 and L3 it is needed for placement and polarity. We find Four-jointed to be strongly expressed in the tendon cells and show how this might explain the orientation of all seven rows. Unexpectedly, we find that L3 that lack Dachsous differ from larvae lacking Fat and we present evidence that this is due to differently mislocalised Dachs. We make some progress in understanding how Dachs contributes to phenotypes of wildtype and mutant larvae and adults.

  18. Planar cell polarity: the Dachsous/Fat system contributes differently to the embryonic and larval stages of Drosophila

    Directory of Open Access Journals (Sweden)

    Pedro Saavedra


    Full Text Available The epidermal patterns of all three larval instars (L1–L3 of Drosophila are made by one unchanging set of cells. The seven rows of cuticular denticles of all larval stages are consistently planar polarised, some pointing forwards, others backwards. In L1 all the predenticles originate at the back of the cells but, in L2 and L3, they form at the front or the back of the cell depending on the polarity of the forthcoming denticles. We find that, to polarise all rows, the Dachsous/Fat system is differentially utilised; in L1 it is active in the placement of the actin-based predenticles but is not crucial for the final orientation of the cuticular denticles, in L2 and L3 it is needed for placement and polarity. We find Four-jointed to be strongly expressed in the tendon cells and show how this might explain the orientation of all seven rows. Unexpectedly, we find that L3 that lack Dachsous differ from larvae lacking Fat and we present evidence that this is due to differently mislocalised Dachs. We make some progress in understanding how Dachs contributes to phenotypes of wildtype and mutant larvae and adults.

  19. Asymmetric localization of Vangl2 and Fz3 indicate novel mechanisms for planar cell polarity in mammals. (United States)

    Montcouquiol, Mireille; Sans, Nathalie; Huss, David; Kach, Jacob; Dickman, J David; Forge, Andrew; Rachel, Rivka A; Copeland, Neal G; Jenkins, Nancy A; Bogani, Debora; Murdoch, Jennifer; Warchol, Mark E; Wenthold, Robert J; Kelley, Matthew W


    Planar cell polarity (PCP) is a process in which cells develop with uniform orientation within the plane of an epithelium. To begin to elucidate the mechanisms of PCP in vertebrates, the localization of the protein Vangl2 (Van Gogh-like) was determined during the development of the mammalian cochlea. Results indicate that Vangl2 becomes asymmetrically localized to specific cell-cell boundaries along the axis of polarization and that this asymmetry is lost in PCP mutants. In addition, PDZ2 (postsynaptic density/Discs large/zona occludens 1), PDZ3, and PDZ4 of the PCP protein Scrb1 (Scribble) are shown to bind to the C-terminal PDZ binding domain of Vangl2, suggesting that Scrb1 plays a direct role in asymmetric targeting of Vangl2. Finally, Fz3 (Frizzled), a newly demonstrated mediator of PCP, is also asymmetrically localized in a pattern that matches that of Vangl2. The presence and asymmetry of Fz3 at the membrane is shown to be dependent on Vangl2. This result suggests a role for Vangl2 in the targeting or anchoring of Fz3, a hypothesis strengthened by the existence of a physical interaction between the two proteins. Together, our data support the idea that protein asymmetry plays an important role in the development of PCP, but the colocalization and interaction of Fz3 and Vangl2 suggests that novel PCP mechanisms exist in vertebrates.

  20. Exocytosis and polarity in plant cells: insights by studying cellulose synthase complexes and the exocyst

    NARCIS (Netherlands)

    Ying Zhang, Ying


    The work presented in this thesis covers aspects of exocytosis, plant cell growth and cell wall formation. These processes are strongly linked as cell growth and cell wall formation occur simultaneously and exocytosis is the process that delivers cell wall components to the existing cell wall and in

  1. Distribution specificity of polarized populations of T helper cells in patients with chronic hepatitis B virus infection

    Institute of Scientific and Technical Information of China (English)

    JIANG Rong-long; FENG Xiao-rong; LU Qiao-sheng; LUO Kang-xian; FU Ning


    Objective: To investigate the roles of the polarized populations of T helper cells isolated from the peripheral blood mononuclear cells (PBMCs) of individuals with chronic hepatitis B virus (HBV) infection. Methods: PBMCs from patients with chronic HBV infection were separated routinely, stimulated by PMA, ionomycin and monensin, and the production of IL-4, IFN-γ and TGF-β by CD4+ T cells was observed by flow cytometry(FACS). Results: The percentages of the T cells producing IFN-γ, IL-4 or TGF-β ranged from 2.3% to 18.6%, 1.1% to 8.7% and 0.7% to 7.1% respectively among CD4+ cells from non-infected individuals. The majority of CD4+ T cells in PBMCs from individuals with chronic HBV infection were Th0 cells. The proportion of Th1 cells in patients with active chronic hepatitis B was higher than that in patients at inactive stage of the disease (P<0.05), indicating a significant elevation of Thl cells with the hepatic inflammation activity. The percentage of Th2 cells in individuals with HBV infection was higher than that in controls (P<0.05),but showed no difference between different patients (P>0.05). The percentage of Th3 cells was higher in asymptomatic HBV carriers than that in patients with chronic hepatitis B and in healthy controls (P<0.05). Conclusions: Th1-type cytokines are related with hepatic inflammation activity of chronic hepatitis B, and Th2 cells may be associated with the persistence of HBV infection. Th3 cells cooperating with Th2 cells are likely to function as negative immunoregulator, and may be responsible for the immune tolerance state of chronic HBV infection.

  2. Proinflammatory-activated glioma cells induce a switch in microglial polarization and activation status, from a predominant M2b phenotype to a mixture of M1 and M2a/B polarized cells

    Directory of Open Access Journals (Sweden)

    Lucia Lisi


    Full Text Available Malignant gliomas are primary brain tumors characterized by morphological and genetic complexities, as well as diffuse infiltration into normal brain parenchyma. Within gliomas, microglia/macrophages represent the largest tumor-infiltrating cell population, contributing by at least one-third to the total tumor mass. Bi-directional interactions between glioma cells and microglia may therefore play an important role on tumor growth and biology. In the present study, we have characterized the influence of glioma-soluble factors on microglial function, comparing the effects of media harvested under basal conditions with those of media obtained after inducing a pro-inflammatory activation state in glioma cells. We found that microglial cells undergo a different pattern of activation depending on the stimulus; in the presence of activated glioma-derived factors, i.e. a condition mimicking the late stage of pathology, microglia presents as a mixture of polarization phenotypes (M1 and M2a/b, with up-regulation of iNOS (inducible nitric oxide synthase, ARG (arginase and IL (interleukine-10. At variance, microglia exposed to basal glioma-derived factors, i.e. a condition resembling the early stage of pathology, shows a more specific pattern of activation, with increased M2b polarization status and up-regulation of IL-10 only. As far as viability and cell proliferation are concerned, both LI-CM [LPS (lipopolysaccharide–IFNγ (interferon γ conditioned media] and C-CM (control-conditioned media induce similar effects on microglial morphology. Finally, in human glioma tissue obtained from surgical resection of patients with IV grade glioblastoma, we detected a significant amount of CD68 positive cells, which is a marker of macrophage/microglial phagocytic activity, suggesting that in vitro findings presented here might have a relevance in the human pathology as well.

  3. Collective cell migration requires suppression of actomyosin at cell-cell contacts mediated by DDR1 and the cell polarity regulators Par3 and Par6


    Hidalgo-Carcedo, Cristina; Hooper, Steven; Chaudhry, Shahid I.; Williamson, Peter; Harrington, Kevin; Leitinger, Birgit; Sahai, Erik


    Collective cell migration occurs in a range of contexts: cancer cells frequently invade in cohorts while retaining cell-cell junctions. Here we show that collective cancer cell invasion depends on reducing actomyosin contractility at sites of cell-cell contact. When actomyosin is not down-regulated at cell-cell contacts migrating cells lose cohesion. We provide a novel molecular mechanism for this down-regulation. Depletion of Discoidin Domain Receptor 1 (DDR1) blocks collective cancer cell i...

  4. T helper type 2-polarized invariant natural killer T cells reduce disease severity in acute intra-abdominal sepsis. (United States)

    Anantha, R V; Mazzuca, D M; Xu, S X; Porcelli, S A; Fraser, D D; Martin, C M; Welch, I; Mele, T; Haeryfar, S M M; McCormick, J K


    Sepsis is characterized by a severe systemic inflammatory response to infection that is associated with high morbidity and mortality despite optimal care. Invariant natural killer T (iNK T) cells are potent regulatory lymphocytes that can produce pro- and/or anti-inflammatory cytokines, thus shaping the course and nature of immune responses; however, little is known about their role in sepsis. We demonstrate here that patients with sepsis/severe sepsis have significantly elevated proportions of iNK T cells in their peripheral blood (as a percentage of their circulating T cells) compared to non-septic patients. We therefore investigated the role of iNK T cells in a mouse model of intra-abdominal sepsis (IAS). Our data show that iNK T cells are pathogenic in IAS, and that T helper type 2 (Th2) polarization of iNK T cells using the synthetic glycolipid OCH significantly reduces mortality from IAS. This reduction in mortality is associated with the systemic elevation of the anti-inflammatory cytokine interleukin (IL)-13 and reduction of several proinflammatory cytokines within the spleen, notably interleukin (IL)-17. Finally, we show that treatment of sepsis with OCH in mice is accompanied by significantly reduced apoptosis of splenic T and B lymphocytes and macrophages, but not natural killer cells. We propose that modulation of iNK T cell responses towards a Th2 phenotype may be an effective therapeutic strategy in early sepsis.

  5. Dengue virus infection elicits highly polarized CX3CR1+ cytotoxic CD4+ T cells associated with protective immunity. (United States)

    Weiskopf, Daniela; Bangs, Derek J; Sidney, John; Kolla, Ravi V; De Silva, Aruna D; de Silva, Aravinda M; Crotty, Shane; Peters, Bjoern; Sette, Alessandro


    Dengue virus (DENV) is a rapidly spreading pathogen with unusual pathogenesis, and correlates of protection from severe dengue disease and vaccine efficacy have not yet been established. Although DENV-specific CD8(+) T-cell responses have been extensively studied, the breadth and specificity of CD4(+) T-cell responses remains to be defined. Here we define HLA-restricted CD4(+) T-cell epitopes resulting from natural infection with dengue virus in a hyperepidemic setting. Ex vivo flow-cytometric analysis of DENV-specific CD4(+) T cells revealed that the virus-specific cells were highly polarized, with a strong bias toward a CX3CR1(+) Eomesodermin(+) perforin(+) granzyme B(+) CD45RA(+) CD4 CTL phenotype. Importantly, these cells correlated with a protective HLA DR allele, and we demonstrate that these cells have direct ex vivo DENV-specific cytolytic activity. We speculate that cytotoxic dengue-specific CD4(+) T cells may play a role in the control of dengue infection in vivo, and this immune correlate may be a key target for dengue virus vaccine development.

  6. [Fluorescence polarization used to investigate the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field]. (United States)

    Zhang, Ying; Zeng, Xin-An; Wen, Qi-Biao; Li, Lin


    To know the lethal mechanism of microorganisms under pulsed electric field treatment, the relationship between the inactivation of Saccharomyces cerevisiae (CICC1308) cell and the permeability and fluidity changes of its cell membrane treated by pulsed electric field (0-25 kV x cm(-1), 0-266 ms) was investigated. With 1,6-diphenyl-1,3,5-hexatriene (DPH) used as a probe, the cell membrane fluidity of Saccharomyces cerevisiae treated by pulsed electric field was expressed by fluorescence polarization. Results showed that the cell membrane fluidity decreases when the electric flied strength is up to 5 kV x cm(-1), and decreases with the increase in electric field strength and treatment time. The plate counting method and ultraviolet spectrophotometer were used to determine the cell viability and to investigate the cell membrane permeability, respectively, treated by pulsed electric field. Results showed that the lethal ratio and the content of protein and nucleic acid leaked from intracellular plasma increased with the increase in the electric field strength and the extension of treatment time. Even in a quite lower electric field of 5 kV x cm(-1) with a tiny microorganism lethal level, the increase in UV absorption value and the decrease in fluidity were significant. It was demonstrated that the cell membrane fluidity decreases with the increase in lethal ratio and cell membrane permeability. The viscosity of cell membrane increases with the decrease in fluidity. These phenomena indicated that cell membrane is one of the most key sites during the pulsed electric field treatment, and the increased membrane permeability and the decreased cell membrane fluidity contribute to the cell death.


    Directory of Open Access Journals (Sweden)

    Makarov, V.


    Full Text Available The generalized scheme and graph-model with factors influencing the motorcar course-keeping stability are suggested. The analysis of possible variants improving the motorcar course-keeping stability is presented in the graph-model.

  8. Polarization of the epithelial layer and apical localization of integrins are required for engulfment of apoptotic cells in the Drosophila ovary

    Directory of Open Access Journals (Sweden)

    Tracy L. Meehan


    Full Text Available Inefficient clearance of dead cells or debris by epithelial cells can lead to or exacerbate debilitating conditions such as retinitis pigmentosa, macular degeneration, chronic obstructive pulmonary disease and asthma. Despite the importance of engulfment by epithelial cells, little is known about the molecular changes that are required within these cells. The misregulation of integrins has previously been associated with disease states, suggesting that a better understanding of the regulation of receptor trafficking could be key to treating diseases caused by defects in phagocytosis. Here, we demonstrate that the integrin heterodimer αPS3/βPS becomes apically enriched and is required for engulfment by the epithelial follicle cells of the Drosophila ovary. We found that integrin heterodimer localization and function is largely directed by the α-subunit. Moreover, proper cell polarity promotes asymmetric integrin enrichment, suggesting that αPS3/βPS trafficking occurs in a polarized fashion. We show that several genes previously known for their roles in trafficking and cell migration are also required for engulfment. Moreover, as in mammals, the same α-integrin subunit is required by professional and non-professional phagocytes and migrating cells in Drosophila. Our findings suggest that migrating and engulfing cells use common machinery, and demonstrate a crucial role for integrin function and polarized trafficking of integrin subunits during engulfment. This study also establishes the epithelial follicle cells of the Drosophila ovary as a powerful model for understanding the molecular changes required for engulfment by a polarized epithelium.

  9. Keeping Secrets : Quantity, Quality and Consequences

    NARCIS (Netherlands)

    Frijns, T.


    Keeping Secrets deals with the consequences of an elusive yet everyday phenomenon. It addresses both the quantity and quality of secret-keeping. With respect to quantity, it presents research on the intra- and interpersonal consequences of keeping secrets from parents in adolescence. With respect t

  10. IL32 is progressively expressed in mycosis fungoides independent of helper T-cell 2 and helper T-cell 9 polarization. (United States)

    Ohmatsu, Hanako; Humme, Daniel; Gulati, Nicholas; Gonzalez, Juana; Möbs, Markus; Suárez-Fariñas, Mayte; Cardinale, Irma; Mitsui, Hiroshi; Guttman-Yassky, Emma; Sterry, Wolfram; Krueger, James G


    Mycosis fungoides, the most common type of cutaneous T-cell lymphoma (CTCL), is characterized by a helper T-cell 2 (Th2) skewing with a mature CD4(+) memory T-cell phenotype. Using skin samples from patients with mycosis fungoides (n = 21), healthy volunteers (n = 17), and individuals with atopic dermatitis (n = 17) and psoriasis (n = 9), we found IL32 mRNA expression significantly higher in mycosis fungoides samples than in samples from benign inflammatory skin diseases, and its expression increases with disease progression. By IHC and immunofluorescence, we confirmed IL32 protein expression in many CD3(+)CD4(+) T cells and some epidermotropic T cells in mycosis fungoides lesions. MyLa cells (a mycosis fungoides cell line) express IL32, which, in turn, could promote cellular proliferation and viability in a dose-dependent fashion. IL32-treated MyLa and CTCL HH cells upregulated cell proliferation and survival genes. Of the major "polarizing" T-cell cytokines, only IFNγ mRNA increases with mycosis fungoides progression and positively correlates with IL32 mRNA expression. Th2 cytokines do not positively correlate with IL32 mRNA expression or mycosis fungoides progression. Furthermore, by flow cytometry, IL32 production by circulating activated T cells in healthy individuals was found in both IFNγ(+) and IFNγ(-) cells but not in IL4(+) or IL13(+) cells. In conclusion, we have identified IL32(+) cells as the likely tumor cells in mycosis fungoides, and demonstrated that IL32 mRNA expression increases with mycosis fungoides progression and is significantly higher than mRNA expression in other skin diseases, and that some IL32(+) T cells are independent from the defined Th subsets. Thus, IL32 may play a unique role in mycosis fungoides progression as an autocrine cytokine.

  11. Clustering and negative feedback by endocytosis in planar cell polarity signaling is modulated by ubiquitinylation of prickle. (United States)

    Cho, Bomsoo; Pierre-Louis, Gandhy; Sagner, Andreas; Eaton, Suzanne; Axelrod, Jeffrey D


    The core components of the planar cell polarity (PCP) signaling system, including both transmembrane and peripheral membrane associated proteins, form asymmetric complexes that bridge apical intercellular junctions. While these can assemble in either orientation, coordinated cell polarization requires the enrichment of complexes of a given orientation at specific junctions. This might occur by both positive and negative feedback between oppositely oriented complexes, and requires the peripheral membrane associated PCP components. However, the molecular mechanisms underlying feedback are not understood. We find that the E3 ubiquitin ligase complex Cullin1(Cul1)/SkpA/Supernumerary limbs(Slimb) regulates the stability of one of the peripheral membrane components, Prickle (Pk). Excess Pk disrupts PCP feedback and prevents asymmetry. We show that Pk participates in negative feedback by mediating internalization of PCP complexes containing the transmembrane components Van Gogh (Vang) and Flamingo (Fmi), and that internalization is activated by oppositely oriented complexes within clusters. Pk also participates in positive feedback through an unknown mechanism promoting clustering. Our results therefore identify a molecular mechanism underlying generation of asymmetry in PCP signaling.

  12. Modifying the NH2 and COOH termini of aquaporin-5: effects on localization in polarized epithelial cells. (United States)

    Wellner, Robert B; Hong, Sohee; Cotrim, Ana P; Swaim, William D; Baum, Bruce J


    To reengineer polarized epithelial cell functions directly in situ, or ex vivo in the fabrication of an artificial organ, it is necessary to understand mechanisms that account for polarized membrane sorting. We have used the aquaporins (AQPs), a family of homotetrameric water channel proteins, as model membrane proteins for this purpose. AQP monomers contain six transmembrane-spanning domains linked by five interconnecting loops, with the NH2 and COOH termini residing in the cytosol. AQP5 is localized in the apical membranes of several different epithelia in vivo, and in stably transfected MDCK-II cells grown as a polarized monolayer. We wished to identify a structural region(s) within rat AQP5 (rAQP5) important for apical localization, and to study the MDCK-II cell localization of rAQP5s modified in either their NH2 or COOH terminus. We show that the NH2- terminal region does not play a major role in apical localization as deletion of the NH2 terminus produced a modified rAQP5 construct (AQP5-NT(del)) that was stably expressed and localized primarily to the apical membranes of MDCK-II cells. Attachment of a FLAG epitope to the NH2 terminus of AQP5 (AQP5(flag) construct) also did not perturb apical localization. In addition, we found that the exchange of NH2-terminal regions between rAQP5 and human AQP1 (hAQP1; a nonpolarized AQP isoform) produced a modified rAQP5 construct (AQP5-1NT) and a modified hAQP1 construct (AQP1-5NT), each of which localized as the parental AQP (apically, and to both apical and basolateral membranes, respectively). In contrast, we found that deletion of the COOH terminus resulted in a modified rAQP5 construct (AQP5-CT(del)) that was unstably expressed and localized to intracellular site(s) in MDCK-II cells. Substitution of the COOH terminus of AQP1 with the COOH terminus of AQP5 also produced a construct (AQP1-5CT) transiently expressed in intracellular compartment(s). However, substitution of the COOH terminus of rAQP5 with the COOH

  13. Compact Circularly Polarized Patch Antenna Using a Composite Right/Left-Handed Transmission Line Unit-Cell

    Directory of Open Access Journals (Sweden)

    L. Geng


    Full Text Available A compact circularly polarized (CP patch antenna using a composite right/left-handed (CRLH transmission line (TL unit-cell is proposed. The CRLH TL unit-cell includes a complementary split ring resonator (CSRR for shunt inductance and a gap loaded with a circular-shaped slot for series capacitance. The CSRR can decrease the TM10 mode resonance frequency, thus reducing the electrical size of the proposed antenna. In addition, the asymmetry of the CSRR brings about the TM01 mode, which can be combined with the TM10 mode by changing the slot radius. The combination of these two orthogonal modes with 90° phase shift makes the proposed antenna provide a CP property. The experimental results show that the proposed antenna has a wider axial ratio bandwidth and a smaller electrical size than the reported CP antennas. Moreover, the proposed antenna is designed without impedance transformer, 90° phase shift, dual feed and ground via.

  14. The planar cell polarity (PCP) protein Diversin translocates to the nucleus to interact with the transcription factor AF9

    Energy Technology Data Exchange (ETDEWEB)

    Haribaskar, Ramachandran; Puetz, Michael; Schupp, Birte; Skouloudaki, Kassiani; Bietenbeck, Andreas; Walz, Gerd [Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg (Germany); Schaefer, Tobias, E-mail: [Renal Division, University Hospital Freiburg, Hugstetter Strasse 55, D-79106 Freiburg (Germany)


    The planar cell polarity (PCP) pathway, a {beta}-catenin-independent branch of the Wnt signaling pathway, orients cells and their appendages with respect to the body axes. Diversin, the mammalian homolog of the Drosophila PCP protein Diego, acts as a molecular switch that blocks {beta}-catenin-dependent and promotes {beta}-catenin-independent Wnt signaling. We report now that Diversin, containing several nuclear localization signals, translocates to the nucleus, where it interacts with the transcription factor AF9. Both Diversin and AF9 block canonical Wnt signaling; however, this occurs independently of each other, and does not require nuclear Diversin. In contrast, AF9 strongly augments the Diversin-driven activation of c-Jun N-terminal kinase (JNK)-dependent gene expression in the nucleus, and this augmentation largely depends on the presence of nuclear Diversin. Thus, our findings reveal that components of the PCP cascade translocate to the nucleus to participate in transcriptional regulation and PCP signaling.

  15. Keeping Up-to-Date

    Directory of Open Access Journals (Sweden)

    Norman L Jones


    Full Text Available As a senior (read older practising respirologist, I have come to appreciate my position as editor, which keeps me current with present practice standards. Everyone talks about the volume and flow of new knowledge, and not a week goes by in which I feel that I know enough to treat my patients optimally. This is particularly the case when it comes to antibiotic usage: the number of antibiotics and the confident way that junior colleagues bandy them about leaves me distinctly depressed because most of the names mean little to me; even the families and generations of antibiotics seem beyond my grasp. That is why I welcomed the request from Dr Lionel Mandell to publish a summary statement on the use of antibiotics in community-acquired pneumonia (CAP, which appears on pages 371-382 of the current issue of the Canadian Respiratory Journal.

  16. Molecular cloning and characterization of a tumor-associated, growth-related, and time-keeping hydroquinone (NADH) oxidase (tNOX) of the HeLa cell surface (United States)

    Chueh, Pin-Ju; Kim, Chinpal; Cho, NaMi; Morre, Dorothy M.; Morre, D. James


    NOX proteins are growth-related cell surface proteins that catalyze both hydroquinone or NADH oxidation and protein disulfide interchange and exhibit prion-like properties. The two enzymatic activities alternate to generate a regular period length of about 24 min. Here we report the expression, cloning, and characterization of a tumor-associated NADH oxidase (tNOX). The cDNA sequence of 1830 bp is located on gene Xq25-26 with an open reading frame encoding 610 amino acids. The activities of the bacterially expressed tNOX oscillate with a period length of 22 min as is characteristic of tNOX activities in situ. The activities are inhibited completely by capsaicin, which represents a defining characteristic of tNOX activity. Functional motifs identified by site-directed mutagenesis within the C-terminal portion of the tNOX protein corresponding to the processed plasma membrane-associated form include quinone (capsaicin), copper and adenine nucleotide binding domains, and two cysteines essential for catalytic activity. Four of the six cysteine to alanine replacements retained enzymatic activity, but the period lengths of the oscillations were increased. A single protein with two alternating enzymatic activities indicative of a time-keeping function is unprecedented in the biochemical literature.

  17. PINCH1 regulates cell-matrix and cell-cell</