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Sample records for 2c protein phosphatases

  1. Molecular cloning of rat type 2C (IA) protein phosphatase mRNA.

    Tamura, S; Lynch, K. R.; Larner, J.; Fox, J.; Yasui, A; Kikuchi, K.; Suzuki, Y.; Tsuiki, S

    1989-01-01

    A full-length cDNA encoding rat type 2C (IA) protein phosphatase was isolated from a kidney cDNA library. The cDNA was identified by screening the library with oligonucleotides based on a partial amino acid sequence determined from purified rat liver phosphatase. This clone is 2.35 kilobase pairs long and has a single extended translation reading frame that predicts a 382-amino acid protein of 42,416 daltons. The deduced amino acid sequence contains segments corresponding to three peptides fr...

  2. ABA Inducible Rice Protein Phosphatase 2C Confers ABA Insensitivity and Abiotic Stress Tolerance in Arabidopsis

    Singh, Amarjeet; Jha, Saroj K.; Bagri, Jayram; Pandey, Girdhar K.

    2015-01-01

    Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa) orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108), which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and t...

  3. ABA inducible rice protein phosphatase 2C confers ABA insensitivity and abiotic stress tolerance in Arabidopsis.

    Amarjeet Singh

    Full Text Available Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108, which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and tolerant to high salt and mannitol stresses during seed germination, root growth and overall seedling growth. At adult stage, OsPP108 overexpression leads to high tolerance to salt, mannitol and drought stresses with far better physiological parameters such as water loss, fresh weight, chlorophyll content and photosynthetic potential (Fv/Fm in transgenic Arabidopsis plants. Expression profile of various stress marker genes in OsPP108 overexpressing plants revealed interplay of ABA dependent and independent pathway for abiotic stress tolerance. Overall, this study has identified a potential rice group A PP2C, which regulates ABA signaling negatively and abiotic stress signaling positively. Transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions.

  4. ABA inducible rice protein phosphatase 2C confers ABA insensitivity and abiotic stress tolerance in Arabidopsis.

    Singh, Amarjeet; Jha, Saroj K; Bagri, Jayram; Pandey, Girdhar K

    2015-01-01

    Arabidopsis PP2C belonging to group A have been extensively worked out and known to negatively regulate ABA signaling. However, rice (Oryza sativa) orthologs of Arabidopsis group A PP2C are scarcely characterized functionally. We have identified a group A PP2C from rice (OsPP108), which is highly inducible under ABA, salt and drought stresses and localized predominantly in the nucleus. Genetic analysis revealed that Arabidopsis plants overexpressing OsPP108 are highly insensitive to ABA and tolerant to high salt and mannitol stresses during seed germination, root growth and overall seedling growth. At adult stage, OsPP108 overexpression leads to high tolerance to salt, mannitol and drought stresses with far better physiological parameters such as water loss, fresh weight, chlorophyll content and photosynthetic potential (Fv/Fm) in transgenic Arabidopsis plants. Expression profile of various stress marker genes in OsPP108 overexpressing plants revealed interplay of ABA dependent and independent pathway for abiotic stress tolerance. Overall, this study has identified a potential rice group A PP2C, which regulates ABA signaling negatively and abiotic stress signaling positively. Transgenic rice plants overexpressing this gene might provide an answer to the problem of low crop yield and productivity during adverse environmental conditions. PMID:25886365

  5. Probing protein phosphatase substrate binding

    Højlys-Larsen, Kim B.; Sørensen, Kasper Kildegaard; Jensen, Knud Jørgen; Gammeltoft, Steen

    2012-01-01

    Proteomics and high throughput analysis for systems biology can benefit significantly from solid-phase chemical tools for affinity pull-down of proteins from complex mixtures. Here we report the application of solid-phase synthesis of phosphopeptides for pull-down and analysis of the affinity...... profile of the integrin-linked kinase associated phosphatase (ILKAP), a member of the protein phosphatase 2C (PP2C) family. Phosphatases can potentially dephosphorylate these phosphopeptide substrates but, interestingly, performing the binding studies at 4 °C allowed efficient binding to phosphopeptides......, without the need for phosphopeptide mimics or phosphatase inhibitors. As no proven ILKAP substrates were available, we selected phosphopeptide substrates among known PP2Cδ substrates including the protein kinases: p38, ATM, Chk1, Chk2 and RSK2 and synthesized directly on PEGA solid supports through a BAL...

  6. AtPP2CG1, a protein phosphatase 2C, positively regulates salt tolerance of Arabidopsis in abscisic acid-dependent manner

    Liu, Xin, E-mail: fangfei6073@126.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhu, Yanming, E-mail: ymzhu2001@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Zhai, Hong, E-mail: Zhai.h@neigaehrb.ac.cn [Northeast Institute of Geography and Agroecology, Chinese Academy of Sciences, Harbin 150040 (China); Cai, Hua, E-mail: small-big@sohu.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Ji, Wei, E-mail: iwei_j@hotmail.com [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Luo, Xiao, E-mail: luoxiao2010@yahoo.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China); Li, Jing, E-mail: lijing@neau.edu.cn [Plant Secondary Metabolism Laboratory, Northeast Agricultural University, Harbin 150030 (China); Bai, Xi, E-mail: baixi@neau.edu.cn [Plant Bioengineering Laboratory, Northeast Agricultural University, Harbin 150030 (China)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer AtPP2CG1 positively regulates salt tolerance in ABA-dependent manner. Black-Right-Pointing-Pointer AtPP2CG1 up-regulates the expression of marker genes in different pathways. Black-Right-Pointing-Pointer AtPP2CG1 expresses in the vascular system and trichomes of Arabidopsis. -- Abstract: AtPP2CG1 (Arabidopsis thaliana protein phosphatase 2C G Group 1) was predicted as an abiotic stress candidate gene by bioinformatic analysis in our previous study. The gene encodes a putative protein phosphatase 2C that belongs to Group G of PP2C. There is no report of Group G genes involved in abiotic stress so far. Real-time RT-PCR analysis showed that AtPP2CG1 expression was induced by salt, drought, and abscisic acid (ABA) treatment. The expression levels of AtPP2CG1 in the ABA synthesis-deficient mutant abi2-3 were much lower than that in WT plants under salt stress suggesting that the expression of AtPP2CG1 acts in an ABA-dependent manner. Over-expression of AtPP2CG1 led to enhanced salt tolerance, whereas its loss of function caused decreased salt tolerance. These results indicate that AtPP2CG1 positively regulates salt stress in an ABA-dependent manner. Under salt treatment, AtPP2CG1 up-regulated the expression levels of stress-responsive genes, including RD29A, RD29B, DREB2A and KIN1. GUS activity was detected in roots, leaves, stems, flower, and trichomes of AtPP2CG1 promoter-GUS transgenic plants. AtPP2CG1 protein was localized in nucleus and cytoplasm via AtPP2CG1:eGFP and YFP:AtPP2CG1 fusion approaches.

  7. Pepper protein phosphatase type 2C, CaADIP1 and its interacting partner CaRLP1 antagonistically regulate ABA signalling and drought response.

    Lim, Chae Woo; Lee, Sung Chul

    2016-07-01

    Abscisic acid (ABA) is a key phytohormone that regulates plant growth and developmental processes, including seed germination and stomatal closing. Here, we report the identification and functional characterization of a novel type 2C protein phosphatase, CaADIP1 (Capsicum annuum ABA and Drought-Induced Protein phosphatase 1). The expression of CaADIP1 was induced in pepper leaves by ABA, drought and NaCl treatments. Arabidopsis plants overexpressing CaADIP1 (CaADIP1-OX) exhibited an ABA-hyposensitive and drought-susceptible phenotype. We used a yeast two-hybrid screening assay to identify CaRLP1 (Capsicum annuum RCAR-Like Protein 1), which interacts with CaADIP1 in the cytoplasm and nucleus. In contrast to CaADIP1-OX plants, CaRLP1-OX plants displayed an ABA-hypersensitive and drought-tolerant phenotype, which was characterized by low levels of transpirational water loss and increased expression of stress-responsive genes relative to those of wild-type plants. In CaADIP1-OX/CaRLP1-OX double transgenic plants, ectopic expression of the CaRLP1 gene led to strong suppression of CaADIP1-induced ABA hyposensitivity during the germinative and post-germinative stages, indicating that CaADIP1 and CaRLP1 act in the same signalling pathway and CaADIP1 functions downstream of CaRLP1. Our results indicate that CaADIP1 and its interacting partner CaRLP1 antagonistically regulate the ABA-dependent defense signalling response to drought stress. PMID:26825039

  8. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

  9. Molecular Mimicry Regulates ABA Signaling by SnRK2 Kinases and PP2C Phosphatases

    Soon, Fen-Fen; Ng, Ley-Moy; Zhou, X. Edward; West, Graham M.; Kovach, Amanda; Tan, M.H. Eileen; Suino-Powell, Kelly M.; He, Yuanzheng; Xu, Yong; Chalmers, Michael J.; Brunzelle, Joseph S.; Zhang, Huiming; Yang, Huaiyu; Jiang, Hualiang; Li, Jun; Yong, Eu-Leong; Cutler, Sean; Zhu, Jian-Kang; Griffin, Patrick R.; Melcher, Karsten; Xu, H. Eric (Van Andel); (Scripps); (NWU); (Purdue); (UCR); (Chinese Aca. Sci.); (NU Singapore)

    2014-10-02

    Abscisic acid (ABA) is an essential hormone for plants to survive environmental stresses. At the center of the ABA signaling network is a subfamily of type 2C protein phosphatases (PP2Cs), which form exclusive interactions with ABA receptors and subfamily 2 Snfl-related kinase (SnRK2s). Here, we report a SnRK2-PP2C complex structure, which reveals marked similarity in PP2C recognition by SnRK2 and ABA receptors. In the complex, the kinase activation loop docks into the active site of PP2C, while the conserved ABA-sensing tryptophan of PP2C inserts into the kinase catalytic cleft, thus mimicking receptor-PP2C interactions. These structural results provide a simple mechanism that directly couples ABA binding to SnRK2 kinase activation and highlight a new paradigm of kinase-phosphatase regulation through mutual packing of their catalytic sites.

  10. Research progress of plant PP2C-type protein phosphatase in ABA signal transduction and adversity stress regulation mechanism%植物 PP2C 蛋白磷酸酶 ABA 信号转导及逆境胁迫调控机制研究进展

    张继红; 陶能国

    2015-01-01

    Protein phosphatase is the most important and pivotal enzymes in reversible protein phosphorylation regula-ting mechanisms.While the PP2C phosphatase is a kind of serine/threonine residues of protein phosphatase,is the largest protein phosphatase family in higher plants,there are 76 family members,widely exists in living organisms. So far,four kinds of PP2C protein phosphatases have been found in plants.Protein kinase and protein phosphatase catalyzed reversible protein phosphorylation,play an important role in plant signal transduction and physiological me-tabolism,protein phosphorylation exist in almost the signal transduction pathway.Numerous academic studies have shown that plant PP2Cs are involved in multiple signal transduction pathways including PP 2C involved in ABA sig-naling pathway,the response to drought,low temperature,salt stress,participated in the plant wound and seed dor-mancy or germination signal pathway,and exist the different regulation mechanism and the enzyme catalytic activity were dependent on the concentrations of Mg2+ or Mn2+ .In plant PP2Cs protein C-terminal,there are a highly con-served catalytic domains,as well as in their N-terminal,their function are different.The review would provide a brief overview of classification,structure of PP 2Cs ,the interaction between ABA receptor and PP2Cs protein,the recent progresses about their roles in ABA and other stress signal transduction pathway in higher plant.%蛋白磷酸酶(protein phosphatase,PP)是蛋白质可逆磷酸化调节机制中的关键酶,而 PP2C 磷酸酶是一类丝氨酸/苏氨酸残基蛋白磷酸酶,是高等植物中最大的蛋白磷酸酶家族,包含76个家族成员,广泛存在于生物体中。迄今为止,在植物体内已经发现了4种 PP2C 蛋白磷酸酶。蛋白激酶和蛋白磷酸酶协同催化蛋白质可逆磷酸化,在植物体内信号转导和生理代谢中起着重要的调节作用,蛋白质的磷酸化几乎存在于所有的信号转导途

  11. Structural Genomics of Protein Phosphatases

    Almo,S.; Bonanno, J.; Sauder, J.; Emtage, S.; Dilorenzo, T.; Malashkevich, V.; Wasserman, S.; Swaminathan, S.; Eswaramoorthy, S.; et al

    2007-01-01

    The New York SGX Research Center for Structural Genomics (NYSGXRC) of the NIGMS Protein Structure Initiative (PSI) has applied its high-throughput X-ray crystallographic structure determination platform to systematic studies of all human protein phosphatases and protein phosphatases from biomedically-relevant pathogens. To date, the NYSGXRC has determined structures of 21 distinct protein phosphatases: 14 from human, 2 from mouse, 2 from the pathogen Toxoplasma gondii, 1 from Trypanosoma brucei, the parasite responsible for African sleeping sickness, and 2 from the principal mosquito vector of malaria in Africa, Anopheles gambiae. These structures provide insights into both normal and pathophysiologic processes, including transcriptional regulation, regulation of major signaling pathways, neural development, and type 1 diabetes. In conjunction with the contributions of other international structural genomics consortia, these efforts promise to provide an unprecedented database and materials repository for structure-guided experimental and computational discovery of inhibitors for all classes of protein phosphatases.

  12. Searching for the role of protein phosphatases in eukaryotic microorganisms

    da-Silva A.M.

    1999-01-01

    Full Text Available Preference for specific protein substrates together with differential sensitivity to activators and inhibitors has allowed classification of serine/threonine protein phosphatases (PPs into four major types designated types 1, 2A, 2B and 2C (PP1, PP2A, PP2B and PP2C, respectively. Comparison of sequences within their catalytic domains has indicated that PP1, PP2A and PP2B are members of the same gene family named PPP. On the other hand, the type 2C enzyme does not share sequence homology with the PPP members and thus represents another gene family, known as PPM. In this report we briefly summarize some of our studies about the role of serine/threonine phosphatases in growth and differentiation of three different eukaryotic models: Blastocladiella emersonii, Neurospora crassa and Dictyostelium discoideum. Our observations suggest that PP2C is the major phosphatase responsible for dephosphorylation of amidotransferase, an enzyme that controls cell wall synthesis during Blastocladiella emersonii zoospore germination. We also report the existence of a novel acid- and thermo-stable protein purified from Neurospora crassa mycelia, which specifically inhibits the PP1 activity of this fungus and mammals. Finally, we comment on our recent results demonstrating that Dictyostelium discoideum expresses a gene that codes for PP1, although this activity has never been demonstrated biochemically in this organism.

  13. SERUM PROTEINS, TRANSAMINASES AND PHOSPHATASES IN MALNUTRITION

    H. Mohammadiha

    1976-07-01

    Full Text Available The levels of serum tota1 protein, albumin, transaminases and phosphatases were estimated in a group of children with severe Marasmus or mild malnutrition in order to identify some of the associated deficiencies in these syndromes. The biochemical pattern was similar in the normal and malnourished children.

  14. Structural and Biochemical Characterization of a Cyanobacterial PP2C Phosphatase Reveals Insights into Catalytic Mechanism and Substrate Recognition

    Yunlong Si

    2016-04-01

    Full Text Available PP2C-type phosphatases play roles in signal transduction pathways related to abiotic stress. The cyanobacterial PP2C-type phosphatase tPphA specifically dephosphorylates the PII protein, which is a key regulator in cyanobacteria adapting to nitrogen-deficient environments. Previous studies have shown that residue His39 of tPphA is critical for the enzyme’s recognition of the PII protein; however, the manner in which this residue determines tPphA substrate specificity is unknown. Here, we solved the crystal structure of H39A, a tPphA variant. The structure revealed that the mutation of residue His39 to alanine changes the conformation and the flexibility of the loop in which residue His39 is located, and these changes affect the substrate specificity of tPphA. Moreover, previous studies have assumed that the FLAP subdomain and the third metal (M3 of tPphA could mutually influence each other to regulate PP2C catalytic activity and substrate specificity. However, despite the variable conformations adopted by the FLAP subdomain, the position of M3 was consistent in the tPphA structure. These results indicate that the FLAP subdomain does not influence M3 and vice versa. In addition, a small screen of tPphA inhibitors was performed. Sanguinarine and Ni2+ were found to be the most effective inhibitors among the assayed chemicals. Finally, the dimeric form of tPphA was stabilized by cross-linkers and still exhibited catalytic activity towards p-nitrophenyl phosphate.

  15. Acid phosphatase purified from Mycoplasma fermentans has protein tyrosine phosphatase-like activity.

    Shibata, K; Noda, M.; Sawa, Y; Watanabe, T.

    1994-01-01

    Acid phosphatase purified from Mycoplasma fermentans dephosphorylated phosphotyrosine-containing lysozyme and Raytide, a peptide substrate for protein tyrosine phosphatases. The optimum pH for Raytide was about 5.5. Raytide phosphatase activity was inhibited by potassium fluoride, sodium molybdate, and sodium orthovanadate and was found to exist in some mycoplasmas.

  16. Specific dephosphorylation by phosphatases 1 and 2A of a nuclear protein structurally and immunologically related to nucleolin

    Schneider, H R; Mieskes, G; Issinger, O G

    1989-01-01

    A new nuclear substrate (N-60) for phosphatase 1 and 2Ac has been described. In contrast to nucleolin (C23), to which it is structurally and immunologically related, N-60 becomes dephosphorylated to 51% and 41% by phosphatases 1 and 2Ac, respectively, within 10 min. Incubation up to 20 min led to a...... complete dephosphorylation of N-60. The two other phosphatases tested (2B and 2C) did not dephosphorylate protein N-60 to the same extent as phosphatases 1 and 2Ac. In the case of nucleolin only 18% phosphate was released by all four phosphatases tested. The activity of both phosphatases, 1 and 2A, could...

  17. CLONING AND SEQUENCE ANALYSIS OF A PROTEIN PHOSPHATASE 2C CODING GENE FROM LEISHMANIA DONOVANI 1S%杜氏利什曼原虫蛋白磷酸酶-2C的基因克隆化

    成军; 夏小兵; 王刚; 刘妍; 钟彦伟; 王琳; 杨继珍

    2001-01-01

    目的克隆杜氏利什曼原虫(Leishmania donovani,Ld)1S株蛋白磷酸酶2C(PP2C)的编码基因,为应用这种编码T细胞抗原的基因进行基因疫苗研究奠定基础。方法体外培养杜氏利什曼原虫1S株无鞭毛体,常规方法从虫体提取制备基因组DNA。以夏科氏利什曼原虫(Leishmania chagasi,Lc)的PP2C基因序列为参照,设计并合成利什曼原虫PP2C基因序列特异性的引物。结果以杜氏利什曼原虫的基因组为模板,利用多聚酶链反应(PCR)技术,扩增获得了杜氏利什曼原虫PP2C的全长编码基因。基因序列测定结果表明,杜氏利什曼原虫1S株PP2C基因序列长度为1 317bp,开放读码框架由1 221bp组成,编码产物为406个氨基酸残基。获得的杜氏利什曼原虫1S株的PP2C基因与来源于夏科氏利什曼原虫的PP2C氨基酸残基序列的同源性为95%(387/406)。结论本研究克隆了杜氏利什曼原虫的PP2C基因,为应用诱导T细胞免疫应答抗原的编码基因进行杜氏利什曼原虫的基因疫苗研究奠定了基础。

  18. Partial purification and characterization of phosphotyrosyl-protein phosphatase(s) from human erythrocyte cytosol

    Phosphotyrosyl-protein phosphatase activity of human erythrocyte cytosol can be resolved into two fractions by DEAE-cellulose chromatography followed by P-cellulose chromatography. Both 32P-Tyr-phosphatases are able to dephosphorylate 32P-Tyr of poly (Glu-Tyr) 4:1 but no angiotensin II and synthetic peptide Asp-Ala-Glu-Tyr-Ala-Ala-Arg-Arg-Gly, previously phosphorylated on tyrosine residues by rat spleen tyrosine-protein kinase. Both 32P-Tyr-phosphatase activities distinctly differ from either 32P-Ser-casein phosphatase activity or acid and alkaline p-nitrophenylphosphatase activities with regard to catalytic and physico-chemical properties such as substrate specificity, chromatographic behavior, response to various effectors

  19. Serum proteins, trace metals and phosphatases in psoriasis

    Bhatnagar M

    1994-01-01

    Full Text Available Serum proteins, zinc, copper, acid phosphatase (AcPase and alkaline phosphatase (AlPase were studied in both active and remission phases of psoriasis. Data were compared with healthy controls, ?1, ? and ? globulins were high in active phase while ?1 and ? globulins were at par in remission phase. Serum copper was low but zinc and alkaline phosphatase were significantly high in both active and remission phases of the disease. Acid phosphatase level was at par in all the experimental groups. Study suggests a positive correlation of globulin, zinc and Alpase in active and remission phase of psoriasis.

  20. Rhizobiales-like Phosphatase 2 from Arabidopsis thaliana Is a Novel Phospho-tyrosine-specific Phospho-protein Phosphatase (PPP) Family Protein Phosphatase.

    Uhrig, R Glen; Labandera, Anne-Marie; Muhammad, Jamshed; Samuel, Marcus; Moorhead, Greg B

    2016-03-11

    Cellular signaling through protein tyrosine phosphorylation is well established in mammalian cells. Although lacking the classic tyrosine kinases present in humans, plants have a tyrosine phospho-proteome that rivals human cells. Here we report a novel plant tyrosine phosphatase from Arabidopsis thaliana (AtRLPH2) that, surprisingly, has the sequence hallmarks of a phospho-serine/threonine phosphatase belonging to the PPP family. Rhizobiales/Rhodobacterales/Rhodospirillaceae-like phosphatases (RLPHs) are conserved in plants and several other eukaryotes, but not in animals. We demonstrate that AtRLPH2 is localized to the plant cell cytosol, is resistant to the classic serine/threonine phosphatase inhibitors okadaic acid and microcystin, but is inhibited by the tyrosine phosphatase inhibitor orthovanadate and is particularly sensitive to inhibition by the adenylates, ATP and ADP. AtRLPH2 displays remarkable selectivity toward tyrosine-phosphorylated peptides versus serine/threonine phospho-peptides and readily dephosphorylates a classic tyrosine phosphatase protein substrate, suggesting that in vivo it is a tyrosine phosphatase. To date, only one other tyrosine phosphatase is known in plants; thus AtRLPH2 represents one of the missing pieces in the plant tyrosine phosphatase repertoire and supports the concept of protein tyrosine phosphorylation as a key regulatory event in plants. PMID:26742850

  1. Dephosphorylation of chicken cardiac myofibril C-protein by protein phosphatases 1 and 2A

    C-Protein, which is a regulatory component of cardiac muscle myofibrils, is phosphorylated in response to β-adrenergic agonists by a cAMP-dependent mechanism and dephosphorylated in response to cholinergic agonists. It is believed that the cAMP-dependent phosphorylation is due to cAMP-dependent protein kinase. The protein phosphatase(s) involved in the dephosphorylation of C-protein has not been determined. In this study, chicken cardiac C-protein was phosphorylated with the cAMP-dependent protein kinase to about 3 mol phosphate/mol C-protein. Incubation of [32P]C-protein with the catalytic subunit of protein phosphatase 1 or 2A rapidly removed 30-40% of 32[P]. Phosphopeptide maps and phosphoamino acid analysis revealed that the major site(s) dephosphorylated by either phosphatase was a phosphothreonine residue(s) located on the same tryptic peptide and on the same CNBr fragment. Increasing the incubation period or the phosphatase concentration did not result in any further dephosphorylation of C-protein by phosphatase 1, but phosphatase 2A completely dephosphorylated C-protein. Preliminary studies showed that the major protein phosphatase associated with the myofibril was phosphatase 2A. These results indicate the phosphatase 2A may be important in the regulation of the phosphorylation state of C-protein

  2. Discovery of Small Molecule Inhibitors of the PH Domain Leucine-Rich Repeat Protein Phosphatase (PHLPP) by Chemical and Virtual Screening

    Sierecki, Emma; Sinko, William; McCammon, J. Andrew; Newton, Alexandra C.

    2010-01-01

    PH domain Leucine-rich repeat protein phosphatase (PHLPP) directly dephosphorylates and inactivates Akt and protein kinase C, poising it as a prime target for pharmacological intervention of two major survival pathways. Here we report on the discovery of small molecule inhibitors of the phosphatase activity of PHLPP, a member of the PP2C family of phosphatases for which there are no general pharmacological inhibitors. First, the Diversity Set of the NCI was screened for inhibition of the puri...

  3. Methods to distinguish various types of protein phosphatase activity

    To distinguish the action of protein Tyr(P) and protein Ser(P)/Thr(P) phosphatases on 32P-labeled phosphoproteins in subcellular fractions different inhibitors and activators are utilized. Comparison of the effects of added compounds provides a convenient, indirect method to characterize dephosphorylation reactions. Protein Tyr(P) phosphatases are specifically inhibited by micromolar Zn2+ or vanadate, and show maximal activity in the presence of EDTA. The other class of cellular phosphatases, specific for protein Ser(P) and Thr(P) residues, are inhibited by fluoride and EDTA. In this class of enzymes two major functional types can be distinguished: those sensitive to inhibition by the heat-stable protein inhibitor-2 and not stimulated by polycations, and those not sensitive to inhibition and stimulated by polycations. Preparation of 32P-labeled Tyr(P) and Ser(P) phosphoproteins also is presented for the direct measurement of phosphatase activities in preparations by the release of acid-soluble [32P]phosphate

  4. Voltage sensitive phosphatases: emerging kinship to protein tyrosine phosphatases from structure-function research

    Kirstin eHobiger

    2015-02-01

    Full Text Available The transmembrane protein Ci-VSP from the ascidian Ciona intestinalis was described as first member of a fascinating family of enzymes, the voltage sensitive phosphatases (VSPs. Ci-VSP and its voltage-activated homologs from other species are stimulated by positive membrane potentials and dephosphorylate the head groups of negatively charged phosphoinositide phosphates (PIPs. In doing so, VSPs act as control centers at the cytosolic membrane surface, because they intervene in signaling cascades that are mediated by PIP lipids. The characteristic motif CX5RT/S in the active site classifies VSPs as members of the huge family of cysteine-based protein tyrosine phosphatases (PTPs. Although PTPs have already been well characterized regarding both, structure and function, their relationship to VSPs has drawn only limited attention so far. Therefore, the intention of this review is to give a short overview about the extensive knowledge about PTPs in relation to the facts known about VSPs. Here, we concentrate on the structural features of the catalytic domain which are similar between both classes of phosphatases and their consequences for the enzymatic function. By discussing results obtained from crystal structures, molecular dynamics simulations, and mutagenesis studies, a possible mechanism for the catalytic cycle of VSPs is presented based on that one proposed for PTPs. In this way, we want to link the knowledge about the catalytic activity of VSPs and PTPs.

  5. Displacement affinity chromatography of protein phosphatase one (PP1 complexes

    Gourlay Robert

    2008-11-01

    Full Text Available Abstract Background Protein phosphatase one (PP1 is a ubiquitously expressed, highly conserved protein phosphatase that dephosphorylates target protein serine and threonine residues. PP1 is localized to its site of action by interacting with targeting or regulatory proteins, a majority of which contains a primary docking site referred to as the RVXF/W motif. Results We demonstrate that a peptide based on the RVXF/W motif can effectively displace PP1 bound proteins from PP1 retained on the phosphatase affinity matrix microcystin-Sepharose. Subsequent co-immunoprecipitation experiments confirmed that each identified binding protein was either a direct PP1 interactor or was in a complex that contains PP1. Our results have linked PP1 to numerous new nuclear functions and proteins, including Ki-67, Rif-1, topoisomerase IIα, several nuclear helicases, NUP153 and the TRRAP complex. Conclusion This modification of the microcystin-Sepharose technique offers an effective means of purifying novel PP1 regulatory subunits and associated proteins and provides a simple method to uncover a link between PP1 and additional cellular processes.

  6. Purification and characterization of a protein phosphatase that dephosphorylates pyruvate kinase in an anoxia tolerant animal.

    Brooks, S P; Storey, K B

    1996-05-01

    A protein phosphatase that dephosphorylates pyruvate kinase (PK) in vitro was purified and characterized from the foot muscle of the anoxia tolerant gastropod mollusc Busycon canaliculatum. Purification involved three steps: negative chromatography through Blue Dextran and CM Sephadex, affinity chromatography on DEAE Sephadex and gel exclusion chromatography on Sephacryl S-400. Pyruvate kinase phosphatase (PK-Pase) activity was monitored by following changes in PK I50 values for L-alanine that had previously been linked to changes in the degree of PK phosphorylation. The purified PK-Pase gave a single band on SDS-polyacrylamide gel electrophoresis with a molecular weight of 41 +/- 1 kdaltons. Isoelectric focusing analysis showed that the PK-Pase had an isoelectric point of 4.2 +/- 0.1. Kinetic analysis showed that the enzyme was a Type 2C protein phosphatase with a pH optimum of 6.5. Maximal activity required the presence of magnesium ions (KM = 7.9 +/- 0.6 microM) although high concentrations of Mg2+ were inhibitory (I50 = 2.3 +/- 0.4 mM). The protein phosphatase activity was not affected by either spermine, cAMP, cGMP, potassium phosphate, tartrate, NaF, HgCl2, citrate or concentrations of CaCl2 less than 10 mM. The enzyme could also use ATP, ADP, and GTP as substrates. PMID:8739044

  7. A new fluorescence-based method identifies protein phosphatases regulating lipid droplet metabolism.

    Bruno L Bozaquel-Morais

    Full Text Available In virtually every cell, neutral lipids are stored in cytoplasmic structures called lipid droplets (LDs and also referred to as lipid bodies or lipid particles. We developed a rapid high-throughput assay based on the recovery of quenched BODIPY-fluorescence that allows to quantify lipid droplets. The method was validated by monitoring lipid droplet turnover during growth of a yeast culture and by screening a group of strains deleted in genes known to be involved in lipid metabolism. In both tests, the fluorimetric assay showed high sensitivity and good agreement with previously reported data using microscopy. We used this method for high-throughput identification of protein phosphatases involved in lipid droplet metabolism. From 65 yeast knockout strains encoding protein phosphatases and its regulatory subunits, 13 strains revealed to have abnormal levels of lipid droplets, 10 of them having high lipid droplet content. Strains deleted for type I protein phosphatases and related regulators (ppz2, gac1, bni4, type 2A phosphatase and its related regulator (pph21 and sap185, type 2C protein phosphatases (ptc1, ptc4, ptc7 and dual phosphatases (pps1, msg5 were catalogued as high-lipid droplet content strains. Only reg1, a targeting subunit of the type 1 phosphatase Glc7p, and members of the nutrient-sensitive TOR pathway (sit4 and the regulatory subunit sap190 were catalogued as low-lipid droplet content strains, which were studied further. We show that Snf1, the homologue of the mammalian AMP-activated kinase, is constitutively phosphorylated (hyperactive in sit4 and sap190 strains leading to a reduction of acetyl-CoA carboxylase activity. In conclusion, our fast and highly sensitive method permitted us to catalogue protein phosphatases involved in the regulation of LD metabolism and present evidence indicating that the TOR pathway and the SNF1/AMPK pathway are connected through the Sit4p-Sap190p pair in the control of lipid droplet biogenesis.

  8. Bioengineered protein phosphatase 2A: Update on need

    Rubiolo, Juan A.; López-Alonso, Henar; Alfonso, Amparo; Vega, Félix V.; Vieytes, Mercedes Rodríguez; Botana, Luis M

    2013-01-01

    Harmful algal blooms caused by phytoplankton can occur in all aquatic environments. Some of the algae present in these blooms are capable of producing extremely potent toxins. Due to climate change and eutrophication, harmful algal blooms are increasing on a global scale. One kind of toxin producing algae are those that produce okadaic acid, its derivatives (dinophysistoxin-1 and 2), and microcystins. These toxins are potent inhibitors of protein phosphatase 2A, so this protein is used to det...

  9. Inhibitors of the Ca2+/calmodulin-dependent protein kinase phosphatase family (CaMKP and CaMKP-N)

    Ca2+/calmodulin-dependent protein kinase phosphatase (CaMKP) and its nuclear isoform CaMKP-N are unique Ser/Thr protein phosphatases that negatively regulate the Ca2+/calmodulin-dependent protein kinase (CaMK) cascade by dephosphorylating multifunctional CaMKI, II, and IV. However, the lack of specific inhibitors of these phosphatases has hampered studies on these enzymes in vivo. In an attempt to obtain specific inhibitors, we searched inhibitory compounds and found that Evans Blue and Chicago Sky Blue 6B served as effective inhibitors for CaMKP. These compounds also inhibited CaMKP-N, but inhibited neither protein phosphatase 2C, another member of PPM family phosphatase, nor calcineurin, a typical PPP family phosphatase. The minimum structure required for the inhibition was 1-amino-8-naphthol-4-sulfonic acid. When Neuro2a cells cotransfected with CaMKIV and CaMKP-N were treated with these compounds, the dephosphorylation of CaMKIV was strongly suppressed, suggesting that these compounds could be used as potent inhibitors of CaMKP and CaMKP-N in vivo as well as in vitro

  10. Receptor-type protein tyrosine phosphatases in cancer

    Yu Du

    2015-02-01

    Full Text Available Protein tyrosine phosphatases (PTPs play an important role in regulating cell signaling events in coordination with tyrosine kinases to control cell proliferation, apoptosis, survival, migration, and invasion. Receptor-type protein tyrosine phosphatases (PTPRs are a subgroup of PTPs that share a transmembrane domain with resulting similarities in function and target specificity. In this review, we summarize genetic and epigenetic alterations including mutation, deletion, amplification, and promoter methylation of PTPRs in cancer and consider the consequences of PTPR alterations in different types of cancers. We also summarize recent developments using PTPRs as prognostic or predictive biomarkers and/or direct targets. Increased understanding of the role of PTPRs in cancer may provide opportunities to improve therapeutic approaches.

  11. Protein phosphatase 2A, a key player in Alzheimer's disease

    Rong LIU; Qing TIAN

    2009-01-01

    Protein phosphatase 2A (PP2A) is the pre-dominant serine/threonine phosphatase in eukaryotic cells. In the brains of patients with Alzheimer's disease (AD), decreased PP2A activities were observed, which is suggested to be involved in neurofibrillary tangle (NFT) formation, disturbed amyloid precursor protein (APP) secretion and neurodegeneration in AD brain. Based on our research and other previous findings, decreased PP2Ac level, decreased PP2A holoenzyme composition, increased level of PP2A inhibitors, increased PP2Ac Leu309 demethylation and Tyr307 phosphorylation underlie PP2A inactivation in AD. β-amyloid (Aβ) over-production, estrogen deficiency and impaired homocys-teine metabolism are the possible up-stream factors that inactivate PP2A in AD neurons. Further studies are required to disclose the role of PP2A in Alzheimer's disease.

  12. Assembly and structure of protein phosphatase 2A

    2009-01-01

    Protein phosphatase 2A (PP2A) represents a conserved family of important protein serine/threonine phosphatases in species ranging from yeast to human. The PP2A core enzyme comprises a scaffold subunit and a catalytic subunit. The heterotrimeric PP2A holoenzyme consists of the core enzyme and a variable regulatory subunit. The catalytic subunit of PP2A is subject to reversible methylation, medi-ated by two conserved enzymes. Both the PP2A core and holoenzymes are regulated through interac-tion with a large number of cellular cofactors. Recent biochemical and structural investigation reveals critical insights into the assembly and function of the PP2A core enzyme as well as two families of holoenzyme. This review focuses on the molecular mechanisms revealed by these latest advances.

  13. Assembly and structure of protein phosphatase 2A

    SHI YiGong

    2009-01-01

    Protein phosphatase 2A (PP2A) represents a conserved family of important protein serinetthreonine phosphatases in species ranging from yeast to human. The PP2A core enzyme comprises a scaffold subunit and a catalytic subunit. The heterotrimeric PP2A holoenzyme consists of the core enzyme and a variable regulatory subunit. The catalytic subunit of PP2A is subject to reversible methylation, mediated by two conserved enzymes. Both the PP2A core and holoenzymes are regulated through interaction with a large number of cellular cofactors. Recent biochemical and structural investigation reveals critical insights into the assembly and function of the PP2A core enzyme as well as two families of holoenzyme. This review focuses on the molecular mechanisms revealed by these latest advances.

  14. Have We Overlooked the Importance of Serine/Threonine Protein Phosphatases in Pancreatic Beta-Cells? Role Played by Protein Phosphatase 2A in Insulin Secretion

    Esser V

    2005-07-01

    Full Text Available Genetic predisposition and environmental influences insidiously converge to cause glucose intolerance and hyperglycemia. Beta-cell compensates by secreting more insulin and when it fails, overt diabetes mellitus ensues. The need to understand the mechanisms involved in insulin secretion cannot be stressed enough. Phosphorylation of proteins plays an important role in regulating insulin secretion. In order to understand how a particular cellular process is regulated by protein phosphorylation the nature of the protein kinases and protein phosphatases involved and the mechanisms that determine when and where these enzymes are active should be investigated. While the actions of protein kinases have been intensely studied within the beta-cell, less emphasis has been placed on protein phosphatases even though they play an important regulatory role. This review focuses on the importance of protein phosphatase 2A in insulin secretion. Most of the present knowledge on protein phosphatase 2A originates from protein phosphatase inhibitor studies on islets and beta-cell lines. The ability of protein phosphatase 2A to change its activity in the presence of glucose and inhibitors provides clues to its role in regulating insulin secretion. An aggressive approach to elucidate the substrates and mechanisms of action of protein phosphatases is crucial to the understanding of phosphorylation events within the beta-cell. Characterizing protein phosphatase 2A within the beta-cell will certainly help us in understanding the mechanisms involved in insulin secretion and provide valuable information for drug development.

  15. Redox Regulation of Protein Tyrosine Phosphatase Activity by Hydroxyl Radical

    Meng, Fan-Guo; Zhang, Zhong-Yin

    2012-01-01

    Substantial evidence suggests that transient production of reactive oxygen species (ROS) such as hydrogen peroxide (H2O2) is an important signaling event triggered by the activation of various cell surface receptors. Major targets of H2O2 include protein tyrosine phosphatases (PTPs). Oxidation of the active site Cys by H2O2 abrogates PTP catalytic activity, thereby potentially furnishing a mechanism to ensure optimal tyrosine phosphorylation in response to a variety of physiological stimuli. ...

  16. Protein tyrosine phosphatases expression during development of mouse superior colliculus

    Reinhard, Jacqueline; Horvat-Bröcker, Andrea; Illes, Sebastian; Zaremba, Angelika; Knyazev, Piotr; Ullrich, Axel; Faissner, Andreas

    2009-01-01

    Protein tyrosine phosphatases (PTPs) are key regulators of different processes during development of the central nervous system. However, expression patterns and potential roles of PTPs in the developing superior colliculus remain poorly investigated. In this study, a degenerate primer-based reverse transcription-polymerase chain reaction (RT-PCR) approach was used to isolate seven different intracellular PTPs and nine different receptor-type PTPs (RPTPs) from embryonic E15 mouse superior col...

  17. Induction of Bone Matrix Protein Expression by Native Bone Matrix Proteins in C2C12 Culture

    ZHEN-MING HU; SEAN A. F. PEEL; STEPHEN K. C. HO; GEORGE K. B. SANDOR; CAMERON M. L. CLOKIE

    2009-01-01

    Objective To study the expression of bone matrix protein (BMP) induced by bovine bone morphogenetic proteins (BMPs) in vitro. Methods Type I collagen, osteopontin (OPN), osteonectin (ON), osteocalcin (OC), and bone sialoprotein (BSP) were detected by immunohistochemistry in C2C12 cultured from day 1 to day 28. Results The signaling of bone matrix protein expression became weaker except for type I collagen, OC and BSP after 5 days. Fourteen days after culture, the positive signaling of type I collagen, OPN, ON, OC, and BSP was gradually declined, and could be detected significantly as compared with that of the negative control on day 28. BMP assay showed that the Ikaline phosphatase (ALP) activity was higher in C2C12 culture than in the control during the 14-day culture. Also, total protein and DNA significantly increased during the 14-day culture. High levels of ALP were seen in preosteoblasts and osteoblsts in vivo and in differentiating ostcoblasts in vitro. ALP was well recognized as a marker reflecting osteoblastic activity. Conclusion Native bovine BMP induces conversion of myoblasts into osteoblasts, produces type 1 collagen, and plays significantly role in osteoinduction and bone matrix mineralization of C2C12 in vitro.

  18. Protein-tyrosine-phosphatase SHPTP2 couples platelet-derived growth factor receptor beta to Ras.

    Bennett, A.M.; Tang, T. L.; SUGIMOTO, S; Walsh, C T; Neel, B G

    1994-01-01

    Protein-tyrosine-phosphatase SHPTP2 (Syp/PTP-1D/PTP2C) is the homologue of the Drosophila corkscrew (csw) gene product, which transmits positive signals from receptor tyrosine kinases. Likewise, SHPTP2 has been implicated in positive signaling from platelet-derived growth factor receptor beta (PDGFR). Upon PDGF stimulation, SHPTP2 binds to the PDGFR and becomes tyrosine-phosphorylated. We have identified tyrosine-542 (pY542TNI) as the major in vivo site of SHPTP2 tyrosine phosphorylation. The...

  19. Protein phosphatase 1α is a Ras-activated Bad phosphatase that regulates interleukin-2 deprivation-induced apoptosis

    Ayllón, Verónica; Martínez-A, Carlos; García, Alphonse; Cayla, Xavier; Rebollo, Angelita

    2000-01-01

    Growth factor deprivation is a physiological mechanism to regulate cell death. We utilize an interleukin-2 (IL-2)-dependent murine T-cell line to identify proteins that interact with Bad upon IL-2 stimulation or deprivation. Using the yeast two-hybrid system, glutathione S-transferase (GST) fusion proteins and co-immunoprecipitation techniques, we found that Bad interacts with protein phosphatase 1α (PP1α). Serine phosphorylation of Bad is induced by IL-2 and its dephosphorylation correlates with appearance of apoptosis. IL-2 deprivation induces Bad dephosphorylation, suggesting the involvement of a serine phosphatase. A serine/threonine phosphatase activity, sensitive to the phosphatase inhibitor okadaic acid, was detected in Bad immunoprecipitates from IL-2-stimulated cells, increasing after IL-2 deprivation. This enzymatic activity also dephosphorylates in vivo 32P-labeled Bad. Treatment of cells with okadaic acid blocks Bad dephosphorylation and prevents cell death. Finally, Ras activation controls the catalytic activity of PP1α. These results strongly suggest that Bad is an in vitro and in vivo substrate for PP1α phosphatase and that IL-2 deprivation-induced apoptosis may operate by regulating Bad phosphorylation through PP1α phosphatase, whose enzymatic activity is regulated by Ras. PMID:10811615

  20. Functional Analysis of Protein Tyrosine Phosphatases in Thrombosis and Hemostasis.

    Rahmouni, Souad; Hego, Alexandre; Delierneux, Céline; Wéra, Odile; Musumeci, Lucia; Tautz, Lutz; Oury, Cécile

    2016-01-01

    Platelets are small blood cells derived from cytoplasmic fragments of megakaryocytes and play an essential role in thrombosis and hemostasis. Platelet activation depends on the rapid phosphorylation and dephosphorylation of key signaling molecules, and a number of kinases and phosphatases have been identified as major regulators of platelet function. However, the investigation of novel signaling proteins has suffered from technical limitations due to the anucleate nature of platelets and their very limited levels of mRNA and de novo protein synthesis. In the past, experimental methods were restricted to the generation of genetically modified mice and the development of specific antibodies. More recently, novel (phospho)proteomic technologies and pharmacological approaches using specific small-molecule inhibitors have added additional capabilities to investigate specific platelet proteins.In this chapter, we report methods for using genetic and pharmacological approaches to investigate the function of platelet signaling proteins. While the described experiments focus on the role of the dual-specificity phosphatase 3 (DUSP3) in platelet signaling, the presented methods are applicable to any signaling enzyme. Specifically, we describe a testing strategy that includes (1) aggregation and secretion experiments with mouse and human platelets, (2) immunoprecipitation and immunoblot assays to study platelet signaling events, (3) detailed protocols to use selected animal models in order to investigate thrombosis and hemostasis in vivo, and (4) strategies for utilizing pharmacological inhibitors on human platelets. PMID:27514813

  1. Protein kinase and phosphatase activities of thylakoid membranes

    Dephosphorylation of the 25 and 27 kDa light-harvesting Chl a/b proteins (LHCII) of the thylakoid membranes is catalyzed by a phosphatase which differs from previously reported thylakoid-bound phosphatases in having an alkaline pH optimum (9.0) and a requirement for Mg2+ ions. Dephosphorylation of the 8.3 kDa psb H gene product requires a Mg2+ ion concentration more than 200 fold higher than that for dephosphorylation of LHC II. The 8.3 kDa and 27 kDa proteins appear to be phosphorylated by two distinct kinases, which differ in substrate specificity and sensitivity to inhibitors. The plastoquinone antagonist 2,5-dibromo-3-methyl-6-isopropyl-benzoquinone (DBMIB) inhibits phosphorylation of the 27 kDa LHC II much more readily than phosphorylation of the 8.3 kDa protein. A similar pattern of inhibition is seen for two synthetic oligopeptides (MRKSATTKKAVC and ATQTLESSSRC) which are analogs of the phosphorylation sites of the two proteins. Possible modes of action of DBMIB are discussed. 45 refs., 7 figs., 3 tabs

  2. Structure determination of T-cell protein-tyrosine phosphatase

    Iversen, L.F.; Møller, K. B.; Pedersen, A.K.;

    2002-01-01

    Protein-tyrosine phosphatase 1B (PTP1B) has recently received much attention as a potential drug target in type 2 diabetes. This has in particular been spurred by the finding that PTP1B knockout mice show increased insulin sensitivity and resistance to diet-induced obesity. Surprisingly, the highly......-crystallize TC-PTP with the same set of inhibitors. This seems to be due to a multimerization process where residues 130-132, the DDQ loop, from one molecule is inserted into the active site of the neighboring molecule, resulting in a continuous string of interacting TC-PTP molecules. Importantly, despite the...

  3. Association of Protein Phosphatase 1γ1 with Spinophilin Suppresses Phosphatase Activity in a Parkinson Disease Model*

    Brown, Abigail M.; Baucum, Anthony J.; Bass, Martha A.; Roger J Colbran

    2008-01-01

    Sustained nigrostriatal dopamine depletion increases the serine/threonine phosphorylation of multiple striatal proteins that play a role in corticostriatal synaptic plasticity, including Thr286 phosphorylation of calcium/calmodulin-dependent protein kinase IIα (CaMKIIα). Mechanisms underlying these changes are unclear, but protein phosphatases play a critical role in the acute modulation of striatal protein phosphorylation. Here we show that dopamine depletion for periods ranging from 3 weeks...

  4. Spatial control of protein phosphatase 2A (de)methylation

    Reversible methylation of the protein phosphatase 2A catalytic subunit (PP2AC) is an important regulatory mechanism playing a crucial role in the selective recruitment of regulatory B subunits. Here, we investigated the subcellular localization of leucine carboxyl methyltransferase (LCMT1) and protein phosphatase methylesterase (PME-1), the two enzymes catalyzing this process. The results show that PME-1 is predominantly localized in the nucleus and harbors a functional nuclear localization signal, whereas LCMT1 is underrepresented in the nucleus and mainly localizes to the cytoplasm, Golgi region and late endosomes. Indirect immunofluorescence with methylation-sensitive anti-PP2AC antibodies revealed a good correlation with the methylation status of PP2AC, demethylated PP2AC being substantially nuclear. Throughout mitosis, demethylated PP2AC is associated with the mitotic spindle and during cytokinesis with the cleavage furrow. Overexpression of PME-1, but not of an inactive mutant, results in increased demethylation of PP2AC in the nucleus, whereas overexpression of a cytoplasmic PME-1 mutant lacking the NLS results in increased demethylation in the cytoplasm-in all cases, however, without any obvious functional consequences. PME-1 associates with an inactive PP2A population, regardless of its esterase activity or localization. We propose that stabilization of this inactive, nuclear PP2A pool is a major in vivo function of PME-1

  5. Significance of the photosystem II core phosphatase PBCP for plant viability and protein repair in thylakoid membranes.

    Puthiyaveetil, Sujith; Woodiwiss, Timothy; Knoerdel, Ryan; Zia, Ahmad; Wood, Magnus; Hoehner, Ricarda; Kirchhoff, Helmut

    2014-07-01

    PSII undergoes photodamage, which results in photoinhibition-the light-induced loss of photosynthetic activity. The main target of damage in PSII is the reaction center protein D1, which is buried in the massive 1.4 MDa PSII holocomplex. Plants have evolved a PSII repair cycle that degrades the damaged D1 subunit and replaces it with a newly synthesized copy. PSII core proteins, including D1, are phosphorylated in high light. This phosphorylation is important for the mobilization of photoinhibited PSII from stacked grana thylakoids to the repair machinery in distant unstacked stroma lamellae. It has been recognized that the degradation of the damaged D1 is more efficient after its dephosphorylation by a protein phosphatase. Recently a protein phosphatase 2C (PP2C)-type PSII core phosphatase (PBCP) has been discovered, which is involved in the dephosphorylation of PSII core proteins. Its role in PSII repair, however, is unknown. Using a range of spectroscopic and biochemical techniques, we report that the inactivation of the PBCP gene affects the growth characteristic of plants, with a decreased biomass and altered PSII functionality. PBCP mutants show increased phosphorylation of core subunits in dark and photoinhibitory conditions and a diminished degradation of the D1 subunit. Our results on D1 turnover in PBCP mutants suggest that dephosphorylation of PSII subunits is required for efficient D1 degradation. PMID:24793754

  6. Human neutrophil calmodulin-binding proteins: identification of the calmodulin-dependent protein phosphatase

    The molecular events in linking neutrophil activation and ligand binding to specific membrane receptors are mediated in part by an increase in intracellular Ca2+. One mechanism by which Ca2+ may trigger neutrophil activation is through Ca2+/calmodulin (CaM)-regulated proteins and enzymes. To determine which Ca2+/CaM-regulated enzymes may be present in the neutrophil, they have used Western blotting techniques and 125I-CaM to identify neutrophil CaM-binding proteins. Eleven proteins with molecular weights ranging from 230K to 13.5K bound 125I-CaM in a Ca2+-dependent manner. One predominant region of 125I-Cam binding was to a 59K protein; a protein with an identical mobility was labeled by an antisera against brain CaM-dependent phosphatase. Ca2+-dependent phosphatase activity, which was inhibited by the CaM antagonist trifluoperazine, was detected in a neutrophil extract; a radioimmunoassay for the phosphatase indicated that it was present in the extract at approximately 0.2 μg/mg protein. Most of the CaM-binding proteins, including the 59K protein, were rapidly degraded upon lysis of the neutrophil. There was a close correlation between the degradation of the 59K protein and the loss of Ca2+-dependent phosphatase activity in the neutrophil extract. Thus, human neutrophils contain numerous CaM-binding proteins which are presumably Ca2+/calmodulin-regulated enzymes and proteins; the 59K protein is a CaM-dependent phosphatase

  7. Structural basis for inhibition of the protein tyrosine phosphatase 1B by phosphotyrosine peptide mimetics

    Groves, M R; Yao, Z J; Roller, P P; Burke, T R; Barford, D

    1998-01-01

    Protein tyrosine phosphatases regulate diverse cellular processes and represent important targets for therapeutic intervention in a number of diseases. The crystal structures of protein tyrosine phosphatase 1B (PTP1B) in complex with small molecule inhibitors based upon two classes of phosphotyrosin

  8. Redox and zinc signalling pathways converging on protein tyrosine phosphatases.

    Bellomo, Elisa; Hogstrand, Christer; Maret, Wolfgang

    2014-10-01

    Zinc ions, though redox-inert, have either pro-antioxidant or pro-oxidant functions at critical junctures in redox metabolism and redox signalling. They are released from cells and in cells, e.g. from metallothionein, a protein that transduces redox signals into zinc signals (1). The released zinc ions inhibit enzymes such as protein tyrosine phosphatases (PTPs), key regulatory enzymes of cellular phosphorylation signalling. The Ki(Zn) value for inhibition of receptor PTPB is 21pM (2). The binding is about as tight as the binding of zinc to zinc metalloenzymes and suggests tonic zinc inhibition. PTP1-B (PTPN1), an enzyme regulating the insulin and leptin receptors and involved in cancer and diabetes pathobiochemistry, has a Ki(Zn) value of about 5nM (3). Zinc ions bind to the enzyme in the closed conformation when additional metal-binding ligands are brought into the vicinity of the active site. In contrast, redox reactions target cysteines in the active sites of PTPs in the open conformation. This work provides a molecular basis how hydrogen peroxide and free zinc ions generated by growth factor signalling stimulate phosphorylation signalling differentially. (Supported by the Biotechnology and Biological Sciences Research Council UK, grant BB/K001442/1.). PMID:26461422

  9. Protein tyrosine phosphatases expression during development of mouse superior colliculus.

    Reinhard, Jacqueline; Horvat-Bröcker, Andrea; Illes, Sebastian; Zaremba, Angelika; Knyazev, Piotr; Ullrich, Axel; Faissner, Andreas

    2009-12-01

    Protein tyrosine phosphatases (PTPs) are key regulators of different processes during development of the central nervous system. However, expression patterns and potential roles of PTPs in the developing superior colliculus remain poorly investigated. In this study, a degenerate primer-based reverse transcription-polymerase chain reaction (RT-PCR) approach was used to isolate seven different intracellular PTPs and nine different receptor-type PTPs (RPTPs) from embryonic E15 mouse superior colliculus. Subsequently, the expression patterns of 11 PTPs (TC-PTP, PTP1C, PTP1D, PTP-MEG2, PTP-PEST, RPTPJ, RPTPε, RPTPRR, RPTPσ, RPTPκ and RPTPγ) were further analyzed in detail in superior colliculus from embryonic E13 to postnatal P20 stages by quantitative real-time RT-PCR, Western blotting and immunohistochemistry. Each of the 11 PTPs exhibits distinct spatiotemporal regulation of mRNAs and proteins in the developing superior colliculus suggesting their versatile roles in genesis of neuronal and glial cells and retinocollicular topographic mapping. At E13, additional double-immunohistochemical analysis revealed the expression of PTPs in collicular nestin-positive neural progenitor cells and RC-2-immunoreactive radial glia cells, indicating the potential functional importance of PTPs in neurogenesis and gliogenesis. PMID:19727691

  10. Protein Phosphatase-1 regulates Rift Valley fever virus replication.

    Baer, Alan; Shafagati, Nazly; Benedict, Ashwini; Ammosova, Tatiana; Ivanov, Andrey; Hakami, Ramin M; Terasaki, Kaori; Makino, Shinji; Nekhai, Sergei; Kehn-Hall, Kylene

    2016-03-01

    Rift Valley fever virus (RVFV), genus Phlebovirus family Bunyaviridae, is an arthropod-borne virus endemic throughout sub-Saharan Africa. Recent outbreaks have resulted in cyclic epidemics with an increasing geographic footprint, devastating both livestock and human populations. Despite being recognized as an emerging threat, relatively little is known about the virulence mechanisms and host interactions of RVFV. To date there are no FDA approved therapeutics or vaccines for RVF and there is an urgent need for their development. The Ser/Thr protein phosphatase 1 (PP1) has previously been shown to play a significant role in the replication of several viruses. Here we demonstrate for the first time that PP1 plays a prominent role in RVFV replication early on during the viral life cycle. Both siRNA knockdown of PP1α and a novel PP1-targeting small molecule compound 1E7-03, resulted in decreased viral titers across several cell lines. Deregulation of PP1 was found to inhibit viral RNA production, potentially through the disruption of viral RNA transcript/protein interactions, and indicates a potential link between PP1α and the viral L polymerase and nucleoprotein. These results indicate that PP1 activity is important for RVFV replication early on during the viral life cycle and may prove an attractive therapeutic target. PMID:26801627

  11. Protein phosphatase 2A in stretch-induced endothelial cell proliferation

    Murata, K.; Mills, I.; Sumpio, B. E.

    1996-01-01

    We previously proposed that activation of protein kinase C is a key mechanism for control of cell growth enhanced by cyclic strain [Rosales and Sumpio (1992): Surgery 112:459-466]. Here we examined protein phosphatase 1 and 2A activity in bovine aortic endothelial cells exposed to cyclic stain. Protein phosphatase 2A activity in the cytosol was decreased by 36.1% in response to cyclic strain for 60 min, whereas the activity in the membrane did not change. Treatment with low concentration (0.1 nM) of okadaic acid enhanced proliferation of both static and stretched endothelial cells in 10% fetal bovine serum. These data suggest that protein phosphatase 2A acts as a growth suppressor and cyclic strain may enhance cellular proliferation by inhibiting protein phosphatase 2A as well as stimulating protein kinase C.

  12. Protein tyrosine phosphatase 1B inhibitors isolated from Artemisia roxburghiana.

    Shah, Muhammad Raza; Ishtiaq; Hizbullah, Syed Muhammad; Habtemariam, Solomon; Zarrelli, Armando; Muhammad, Akhtar; Collina, Simona; Khan, Inamulllah

    2016-08-01

    Artemisia roxburghiana is used in traditional medicine for treating various diseases including diabetes. The present study was designed to evaluate the antidiabetic potential of active constituents by using protein tyrosine phosphatase 1B (PTP1B) as a validated target for management of diabetes. Various compounds were isolated as active principles from the crude methanolic extract of aerial parts of A. roxburghiana. All compounds were screened for PTP1B inhibitory activity. Molecular docking simulations were performed to investigate the mechanism behind PTP1B inhibition of the isolated compound and positive control, ursolic acid. Betulinic acid, betulin and taraxeryl acetate were the active PTP1B principles with IC50 values 3.49 ± 0.02, 4.17 ± 0.03 and 87.52 ± 0.03 µM, respectively. Molecular docking studies showed significant molecular interactions of the triterpene inhibitors with Gly220, Cys215, Gly218 and Asp48 inside the active site of PTP1B. The antidiabetic activity of A. roxburghiana could be attributed due to PTP1B inhibition by its triterpene constituents, betulin, betulinic acid and taraxeryl acetate. Computational insights of this study revealed that the C-3 and C-17 positions of the compounds needs extensive optimization for the development of new lead compounds. PMID:26118418

  13. Interaction of Protein Phosphatase 1δ with Nucleophosmin in Human Osteoblastic Cells

    Protein phosphorylation and dephosphorylation has been recognized as an essential mechanism in the regulation of cellular metabolism and function in various tissues. Serine and threonine protein phosphatases (PP) are divided into four categories: PP1, PP2A, PP2B, and PP2C. At least four isoforms of PP1 catalytic subunit in rat, PP1α, PP1γ1, PP1γ2, and PP1δ, were isolated. In the present study, we examined the localization and expression of PP1δ in human osteoblastic Saos-2 cells. Anti-PP1δ antibody recognized a protein present in the nucleolar regions in Saos-2 cells. Cellular fractionation revealed that PP1δ is a 37 kDa protein localized in the nucleolus. Nucleophosmin is a nucleolar phosphoprotein and located mainly in the nucleolus. Staining pattern of nucleophosmin in Saos-2 cells was similar to that of PP1δ. PP1δ and nucleophosmin were specifically stained as dots in the nucleus. Dual fluorescence images revealed that PP1δ and nucleophosmin were localized in the same regions in the nucleolus. Similar distribution patterns of PP1δ and nucleophosmin were observed in osteoblastic MG63 cells. The interaction of PP1δ and nucleophosmin was also shown by immunoprecipitation and Western analysis. These results indicated that PP1δ associate with nucleophosmin directly in the nucleolus and suggested that nucleophosmin is one of the candidate substrate for PP1δ

  14. Inhibition of CDC25B Phosphatase Through Disruption of Protein-Protein Interaction

    Lund, George; Dudkin, Sergii; Borkin, Dmitry; Ni, Wendi; Grembecka, Jolanta; Cierpicki, Tomasz [Michigan

    2015-04-29

    CDC25 phosphatases are key cell cycle regulators and represent very attractive but challenging targets for anticancer drug discovery. Here, we explored whether fragment-based screening represents a valid approach to identify inhibitors of CDC25B. This resulted in identification of 2-fluoro-4-hydroxybenzonitrile, which directly binds to the catalytic domain of CDC25B. Interestingly, NMR data and the crystal structure demonstrate that this compound binds to the pocket distant from the active site and adjacent to the protein–protein interaction interface with CDK2/Cyclin A substrate. Furthermore, we developed a more potent analogue that disrupts CDC25B interaction with CDK2/Cyclin A and inhibits dephosphorylation of CDK2. Based on these studies, we provide a proof of concept that targeting CDC25 phosphatases by inhibiting their protein–protein interactions with CDK2/Cyclin A substrate represents a novel, viable opportunity to target this important class of enzymes.

  15. Catalytic activity of a novel serine/threonine protein phosphatase PP5 from Leishmania major

    Norris-Mullins Brianna

    2014-01-01

    Full Text Available Leishmaniasis is a vector-borne disease caused by protozoan parasites of the genus Leishmania. Our knowledge of protein phosphatases (PPs and their implication in signaling events is very limited. Here we report the expression, characterization and mutagenesis analysis of a novel protein phosphatase 5 (PP5 in Leishmania major. Recombinant PP5 is a bona fide phosphatase and is enzymatically active. Site-directed mutagenesis revealed auto-inhibitory roles of the N-terminal region. This is a rational first approach to understand the role of PP5 in the biology of the parasite better as well as its potential future applicability to anti-parasitic intervention.

  16. PAPP2C Interacts with the Atypical Disease Resistance Protein RPW8.2 and Negatively Regulates Salicylic Acid-Dependent Defense Responses in Arabidopsis

    Wen-Ming Wang; Xian-Feng Ma; Yi Zhang; Ming-Cheng Luo; Guo-Liang Wang; Maria Bellizzi; Xing-Yao Xiong; Shun-Yuan Xiao

    2012-01-01

    Many fungal and oomycete pathogens differentiate a feeding structure named the haustorium to extract nutrition from the plant epidermal cell.The atypical resistance (R) protein RPW8.2 activates salicylic acid (SA)-dependent,haustorium-targeted defenses against Golovinomyces spp.,the causal agents of powdery mildew diseases on multiple plant species.How RPW8.2 activates defense remains uncharacterized.Here,we report that RPW8.2 interacts with the phytochrome-associated protein phosphatase type 2C (PAPP2C) in yeast and in planta as evidenced by coimmunoprecipitation and bimolecular fluorescence complementation assays.Down-regulation of PAPP2C by RNA interference (RNAi) in Col-0 plants lacking RPW8.2 leads to leaf spontaneous cell death and enhanced disease resistance to powdery mildew via the SA-dependent signaling pathway.Moreover,down-regulation of PAPP2C by RNAi in the RPW8.2 background results in strong HR-like cell death,which correlates with elevated RPW8.2 expression.We further demonstrate that hemagglutinin (HA)-tagged PAPP2C prepared from tobacco leaf cells transiently transformed with HA-PAPP2C possesses phosphatase activity.In addition,silencing a rice gene (Os04g0452000) homologous to PAPP2C also results in spontaneous cell death in rice.Combined,our results suggest that RPW8.2 is functionally connected with PAPP2C and that PAPP2C negatively regulates SA-dependent basal defense against powdery mildew in Arabidopsis.

  17. Acrylamide gel electrophoresis of proteins, acid phosphatases and RN-ases from three potato varieties

    A. Kubicz; E. Wieczorek; B. Morawiecka

    2015-01-01

    Studies on variety differences in the protein and acid phosphatase patterns as well as ribunuclease activity distribution were carried out by disc electrophoresis on saline extracts of three varieties of the potato Solanum tuberosum (L.). The protein bands varied in number, position and relative abundance. One main zone of the acid phosphatase activity was detected consisting of 2-3 electrophoretically different bands. Variety differences were concerned with the number and relative abundance ...

  18. Deletion of conserved protein phosphatases reverses defects associated with mitochondrial DNA damage in Saccharomyces cerevisiae

    Garipler, Görkem; Mutlu, Nebibe; Lack, Nathan; Dunn, Cory David

    2014-01-01

    Mitochondrial biogenesis is regulated by signaling pathways sensitive to extracellular conditions and to the internal environment of the cell. Therefore, treatments for disease caused by mutation of mtDNA may emerge from studies of how signal transduction pathways command mitochondrial function. We have examined the role of phosphatases under the control of the conserved alpha 4/Tap42 protein in cells lacking a mitochondrial genome. We found that deletion of protein phosphatase 2A (PP2A) or o...

  19. STRIATAL-ENRICHED PROTEIN TYROSINE PHOSPHATASE (STEP) KNOCKOUT MICE HAVE ENHANCED HIPPOCAMPAL MEMORY

    Venkitaramani, Deepa V.; Moura, Paula J.; Picciotto, Marina R.; Lombroso, Paul J.

    2011-01-01

    STEP is a brain-specific phosphatase that opposes synaptic strengthening by the regulation of key synaptic signaling proteins. Previous studies suggest a possible role for STriatal-Enriched protein tyrosine Phosphatase (STEP) in learning and memory. To demonstrate the functional importance of STEP in learning and memory, we generated STEP knockout (KO) mice and examined the effect of deletion of STEP on behavioral performance, as well as the phosphorylation and expression of its substrates. H...

  20. Stimulation of protein phosphatase activity by insulin and growth factors in 3T3 cells

    Incubation of Swiss mouse 3T3-D1 cells with physiological concentrations of insulin resulted in a rapid and transient activation of protein phosphatase activity as measure by using [32P]phosphorylase α as substrate. Activation reached a maximum level (140% of control value) within 5 min of addition and returned to control levels within 20 min. The effect of insulin was dose-dependent with half-maximal activation occurring at ∼5 nM insulin. This activity could be completely inhibited by addition of the heat-stable protein inhibitor 2, which suggests the presence of an activated type-1 phosphatase. Similar effects on phosphatase activity were seen when epidermal growth factor and platelet-derived growth factor were tested. These results suggest that some of the intracellular effects caused by insulin and growth factors are mediated through the activation of a protein phosphatase

  1. The endogenous inhibitor of protein kinase-C in the rat ovary is a protein phosphatase.

    Eyster, K M; Waller, M S; Miller, T L; Miller, C J; Johnson, M J; Persing, J S

    1993-09-01

    Calcium- and lipid-dependent protein kinase (PKC) activity in the ovary of the pseudopregnant rat is masked by an endogenous inhibitor of PKC. These studies were undertaken to examine the mechanism of action of the endogenous inhibitor of PKC in the rat ovary. The addition of the phosphatase inhibitors calyculin-A (0.09 nM), microcystin-LR (6.4 nM), and okadaic acid (10 nM) resulted in the loss of PKC inhibitory activity and an increase in basal PKC activity in rat ovarian cytosol. In phosphatase assays, significant dephosphorylation of histone-III-S or myelin basic protein that had been phosphorylated by PKC occurred within 4 min after the addition of ovarian cytosol from the pseudopregnant rat. This dephosphorylation was prevented from the pseudopregnant rat. This dephosphorylation was prevented by the addition of calyculin-A (0.73 nM) and was removed by fractionation of ovarian cytosol on diethylaminoethyl cellulose. No inhibition of PKC activity was observed when the PKC-specific peptides AcMBP-(4-14) and [Ser25]PKC-(19-31) were used as the substrate for phosphorylation. In addition, rat ovarian cytosol did not exhibit phosphatase activity when the peptide AcMBP-(4-14) was used as the substrate. Addition of ovarian cytosol resulted in dephosphorylation of phosphorylase-alpha phosphorylated by phosphorylase kinase, but not dephosphorylation of histone-II-A or histone-VIII-S phosphorylated by PKA. The data suggest that the endogenous inhibitor of PKC in the rat ovary is a protein phosphatase. PMID:7689949

  2. Response to DNA damage: why do we need to focus on protein phosphatases?

    MidoriShimada

    2013-01-01

    Full Text Available Eukaryotic cells are continuously threatened by unavoidable errors during normal DNA replication or various sources of genotoxic stresses that cause DNA damage or stalled replication. To maintain genomic integrity, cells have developed a coordinated signaling network, known as the DNA damage response (DDR. Following DNA damage, sensor molecules detect the presence of DNA damage and transmit signals to downstream transducer molecules. This in turn conveys the signals to numerous effectors, which initiate a large number of specific biological responses, including transient cell cycle arrest mediated by checkpoints, DNA repair, and apoptosis. It is recently becoming clear that dephosphorylation events are involved in keeping DDR factors inactive during normal cell growth. Moreover, dephosphorylation is required to shut off checkpoint arrest following DNA damage and has been implicated in the activation of the DDR. Spatial and temporal regulation of phosphorylation events is essential for the DDR, and fine-tuning of phosphorylation is partly mediated by protein phosphatases. While the role of kinases in the DDR has been well documented, the complex roles of protein dephosphorylation have only recently begun to be investigated. Therefore, it is important to focus on the role of phosphatases and to determine how their activity is regulated upon DNA damage. In this work, we summarize current knowledge on the involvement of serine/threonine phosphatases, especially the protein phosphatase 1, protein phosphatase 2A, and protein phosphatase Mg2+/Mn2+-dependent families, in the DDR.

  3. Protein Phosphatase 2Cβl Regulates Human Pregnane X Receptor-Mediated CYP3A4 Gene Expression in HepG2 Liver Carcinoma Cells

    Pondugula, Satyanarayana R.; Tong, Alexander A.; Wu, Jing; Cui, Jimmy; Chen, Taosheng

    2010-01-01

    The human pregnane X receptor (hPXR) regulates the expression of CYP3A4, which plays a vital role in hepatic drug metabolism and has considerably reduced expression levels in proliferating hepatocytes. We have recently shown that cyclin-dependent kinase 2 (CDK2) negatively regulates hPXR-mediated CYP3A4 gene expression. CDK2 can be dephosphorylated and inactivated by protein phosphatase type 2C beta isoform long (PP2Cβl), a unique phosphatase that was originally cloned from human liver. In th...

  4. One-Pot N2C/C2C/N2N Ligation To Trap Weak Protein-Protein Interactions.

    Zhao, Lei; Ehrt, Christiane; Koch, Oliver; Wu, Yao-Wen

    2016-07-01

    Weak transient protein-protein interactions (PPIs) play an essential role in cellular dynamics. However, it is challenging to obtain weak protein complexes owing to their short lifetime. Herein we present a general and facile method for trapping weak PPIs in an unbiased manner using proximity-induced ligations. To expand the chemical ligation spectrum, we developed novel N2N (N-terminus to N-terminus) and C2C (C-terminus to C-terminus) ligation approaches. By using N2C (N-terminus to C-terminus), N2N, and C2C ligations in one pot, the interacting proteins were linked. The weak Ypt1:GDI interaction drove C2C ligation with t1/2 of 4.8 min and near quantitative conversion. The Ypt1-GDI conjugate revealed that binding of Ypt1 G-domain causes opening of the lipid-binding site of GDI, which can accommodate one prenyl group, giving insights into Rab membrane recycling. Moreover, we used this strategy to trap the KRas homodimer, which plays an important role in Ras signaling. PMID:27213482

  5. HSP105 Recruits Protein Phosphatase 2A To Dephosphorylate β-Catenin

    Yu, Nancy; Kakunda, Michael; Pham, Victoria; Lill, Jennie R.; Du, Pan; Wongchenko, Matthew; Yan, Yibing; Firestein, Ron; Huang, Xiaodong

    2015-01-01

    The Wnt/β-catenin pathway causes accumulation of β-catenin in the cytoplasm and its subsequent translocation into the nucleus to initiate the transcription of the target genes. Without Wnt stimulation, β-catenin forms a complex with axin (axis inhibitor), adenomatous polyposis coli (APC), casein kinase 1α (CK1α), and glycogen synthase kinase 3β (GSK3β) and undergoes phosphorylation-dependent ubiquitination. Phosphatases, such as protein phosphatase 2A (PP2A), interestingly, also are component...

  6. High-Throughput Screening of Substrate Specificity for Protein Tyrosine Phosphatases (PTPs) on Phosphopeptide Microarrays.

    Gao, Liqian; Lee, Su Seong; Chen, Jun; Sun, Hongyan; Zhao, Yuliang; Chai, Zhifang; Hu, Yi

    2016-01-01

    Phosphatases are a family of enzymes responsible for the dephosphorylation of biomolecules. Phosphatases play essential roles in cell cycle regulation, signal transduction, and cellular communication. In recent years, one type of phosphatases, protein tyrosine phosphatases (PTPs), emerges as important therapeutic targets for complex and devastating diseases. Nevertheless, the physiological roles, substrate specificity, and downstream targets for PTPs remain largely unknown. To demonstrate how microarrays can be applied to characterizing PTPs, we describe here a phosphopeptide microarray strategy for activity-based high-throughput screening of PTPs substrate specificity. This is followed by a kinetic microarray assay and microplate assay to determine the rate constants of dephosphorylation by PTPs. This microarray strategy has been successfully applied to identifying several potent and selective substrates against different PTPs. These substrates could be used to design potent and selective PTPs inhibitors in the future. PMID:26614076

  7. Latent phosphorylase phosphatases from rat liver: relationship with the heat-stable inhibitory protein.

    Jett, M F; Hers, H G

    1981-08-01

    A high-speed supernatant from rat liver contains at least two latent phosphorylase phosphatases the activities of which are revealed by treatment with ethanol, urea, mercaptoethanol or trypsin. This fraction also contains at least one protein which, after heating, inhibits to various degrees the activated form(s) of the two phosphatases. The two latent enzymes can be separated by cellulase-phosphate chromatography and can be differentiated by their preferential activation by ethanol or trypsin and by their different sensitivity to the inhibitory protein after ethanol activation. Activation of the latent phosphorylase phosphatases by ethanol, urea or mercaptoethanol is not accompanied by the destruction of the precursor of the inhibitory protein whereas activation by trypsin is. However, trypsin treatment of fractions previously activated by ethanol decreases their activity and also increases their sensitivity to the inhibitory protein in a way which is unrelated to the destruction of this inhibitor. Furthermore, some protein fractions, almost free of the precursor of the inhibitory protein can be readily activated by trypsin. In is concluded that the activation of the latent phosphorylase phosphorylase phosphatases is unrelated to the destruction of the inhibitory protein. PMID:6269850

  8. A novel role for protein tyrosine phosphatase 1B as a positive regulator of neuroinflammation

    Song, Gyun Jee; Jung, Myungsu; Kim, Jong-Heon; Park, Hana; Rahman, Md. Habibur; Zhang, Sheng; Zhang, Zhong-Yin; Park, Dong Ho; Kook, Hyun; Lee, In-Kyu; Suk, Kyoungho

    2016-01-01

    Background Protein tyrosine phosphatase 1B (PTP1B) is a member of the non-transmembrane phosphotyrosine phosphatase family. Recently, PTP1B has been proposed to be a novel target of anti-cancer and anti-diabetic drugs. However, the role of PTP1B in the central nervous system is not clearly understood. Therefore, in this study, we sought to define PTP1B’s role in brain inflammation. Methods PTP1B messenger RNA (mRNA) and protein expression levels were examined in mouse brain and microglial cel...

  9. Phosphatase Activity of Microbial Populations in Different Milk Samples in Relation to Protein and Carbohydrate Content

    Sosanka Protim SANDILYA

    2014-12-01

    Full Text Available Cattle milk is a rich source of protein, carbohydrate, vitamins, minerals and all other major and micro nutrients. At a moderate pH, milk is an excellent media for the growth of microbes and thus, intake of raw milk is precarious. In this study, attempt was made for a qualitative study of eight raw milk samples of different varieties of cow and goat milk, collected from Jorhat district of Assam, India, on the basis of nutritional value and microbial population. The highest microbial population was found in the milk collected from cross hybrid variety of cow, whereas microbial contamination was the least in Jersey cow milk. Samples of C1 (Jersey cow variety showed presence of the highest amount of protein and carbohydrate content as compared to the others. Almost all the milk samples showed positive acid and alkaline phosphatase activity. Maximum acid phosphatase activity was observed in cross hybrid cow milk, whereas local cow milk exhibited the highest alkaline phosphatase activity. Phosphatase activity did not show any co-relationship with microbial population of the milk samples. Similarly, the protein and carbohydrate content of the samples did not have any significant impact on both acid and alkaline phosphatase activity.

  10. Molecular Cloning and Functional Expression of a Protein-Serine/Threonine Phosphatase from the Hyperthermophilic Archaeon Pyrodictium abyssi TAG11

    Mai, Bianca; Frey, Gerhard; Swanson, Ronald V.; Mathur, Eric J.; Stetter, K. O.

    1998-01-01

    An open reading frame coding for a putative protein-serine/threonine phosphatase was identified in the hyperthermophilic archaeon Pyrodictium abyssi TAG11 and named Py-PP1. Py-PP1 was expressed in Escherichia coli, purified from inclusion bodies, and biochemically characterized. The phosphatase gene is part of an operon which may provide, for the first time, insight into a physiological role for archaeal protein phosphatases in vivo. PMID:9696747

  11. Kinetics and Mechanism of Protein Tyrosine Phosphatase 1B (PTP1B) Inactivation by Acrolein

    Seiner, Derrick R.; LaButti, Jason N.; Gates, Kent S.

    2007-01-01

    Human cells are exposed to the electrophilic α,β-unsaturated aldehyde acrolein from a variety of sources. Reaction of acrolein with functionally critical protein thiol residues can yield important biological consequences. Protein tyrosine phosphatases (PTPs) are an important class of cysteine-dependent enzymes whose reactivity with acrolein previously has not been well characterized. These enzymes catalyze the dephosphorylation of phosphotyrosine residues on proteins via a phosphocysteine int...

  12. MALDI mass sequencing and biochemical characterization of Setaria cervi protein tyrosine phosphatase.

    Rai, Reeta; Singh, Neetu; Elesela, Srikanth; Tiwari, Savitri; Rathaur, Sushma

    2013-01-01

    A 30-kDa acid phosphatase with protein tyrosine phosphatase activity was identified in Setaria cervi (ScPTP). The enzyme was purified to homogeneity using three-step column chromatography. Matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) analysis of purified ScPTP yielded a total of eight peptides matching most closely to phosphoprotein phosphatase of Ricinus communis (RcPP). A hydrophilicity plot of RcPP revealed the presence of these peptides in the hydrophilic region, suggesting their antigenic nature. The substrate specificity of ScPTP with ortho-phospho-L-tyrosine and inhibition with sodium orthovanadate and ammonium molybdate affirmed it as a protein tyrosine phosphatase. ScPTP was also found to be tartrate resistant. The Km and Vmax were 6.60 mM and 83.3 μM/ml/min, respectively, with pNPP and 8.0 mM and 111 μM/ml/min, respectively, with ortho-phospho-L-tyrosine as the substrate. The Ki value with sodium orthovanadate was calculated to be 16.10 mM. Active site modification with DEPC, EDAC and pHMB suggested the presence of histidine, cysteine and aspartate at its active site. Thus, on the basis of MALDI-TOF and biochemical studies, it was confirmed that purified acid phosphatase is a PTP. PMID:23052758

  13. Free Fatty Acids Inhibit Protein Tyrosine Phosphatase 1B and Activate Akt

    Eisuke Shibata

    2013-09-01

    Full Text Available Background/Aims: Accumulating evidence has suggested that free fatty acids (FFAs interact with protein kinases and protein phosphatases. The present study examined the effect of FFAs on protein phosphatases and Akt. Methods: Activities of protein phosphatase 1 (PP1, protein phosphatase 2A (PP2A, and protein tyrosine phosphatase 1B (PTP1B were assayed under the cell-free conditions. Phosphorylation of Akt was monitored in MSTO-211H human malignant pleural mesothelioma cells without and with knocking-down phosphatidylinositol 3 kinase (PI3K or 3-phosphoinositide-dependent protein kinase-1 (PDK1. Results: In the cell-free assay, unsaturated FFAs (uFFAs such as oleic, linoleic and linolenic acid and saturated FFAs (sFFAs such as stearic, palmitic, myristic, and behenic acid markedly reduced PTP1B activity, with the potential for uFFAs greater than that for sFFAs. All the investigated sFFAs inhibited PP2A activity, but otherwise no inhibition was obtained with uFFAs. Both uFFAs and sFFAs had no effect on PP1 activity. Oleic acid phosphorylated Akt both on Thr308 and Ser473, while stearic acid phosphorylated Akt on Thr308 alone. The effects of oleic and stearic acid on Akt phosphorylation were abrogated by the PI3K inhibitor wortmannin or the PDK1 inhibitor BX912 and also by knocking-down PI3K or PDK1. Conclusion: The results of the present study indicate that uFFAs and sFFAs could activate Akt through a pathway along a PI3K/PDK1/Akt axis in association with PTP1B inhibition.

  14. Expression of protein-tyrosine phosphatases in the major insulin target tissues

    Norris, K; Norris, F; Kono, D H;

    1997-01-01

    Protein-tyrosine phosphatases (PTPs) are key regulators of the insulin receptor signal transduction pathway. We have performed a detailed analysis of PTP expression in the major human insulin target tissues or cells (liver, adipose tissue, skeletal muscle and endothelial cells). To obtain a repre...

  15. Identification, purification, and characterization of phosphotyrosine-specific protein phosphatases from cultured chicken embryo fibroblasts

    Tyrosine phosphorylation catalyzed by a unique class of protein kinases is an important process in both normal cell proliferation and oncogenic transformation. In this study, phosphoprotein phosphatases specific for the dephosphorylation of phosphotyrosine residues were partially purified from secondary chicken embryo fibroblasts, using 32P-labeled immunoglobulin G. The soluble activity was purified by using DEAE-cellulose and carboxymethyl cellulose column chromatography and gel filtration, and at least three enzyme species of apparent Mr 55,000 (pTPI), 50,000 (pTPII), and 95,000 (pTPIII) were resolved. All three enzymes possessed somewhat similar properties. They had a pH optimum of about 7.4, they were inhibited by Zn2+, vanadate, ATP, and ADP, and they were unaffected by divalent metal cations, EDTA, and F- under standard assay conditions employing a physiological ionic strength. These properties suggest that they represent a class of enzymes distinct from well-known phosphoseryl-phosphothreonyl-protein phosphatases and that dephosphorylation of phosphotyrosine-containing proteins may be carried out by a unique family of phosphoprotein phosphatases. Transformation by Rous sarcoma virus resulted in a small increase in phosphotyrosyl-protein phosphatase activity

  16. Dexamethasone Causes Sustained Expression of Mitogen-Activated Protein Kinase (MAPK) Phosphatase 1 and Phosphatase-Mediated Inhibition of MAPK p38

    Lasa, Marina; Abraham, Sonya M.; Boucheron, Christine; Saklatvala, Jeremy; Clark, Andrew R.

    2002-01-01

    The stress-activated protein kinase p38 stabilizes a number of mRNAs encoding inflammatory mediators, such as cyclooxygenase 2 (Cox-2). In HeLa cells the anti-inflammatory glucocorticoid dexamethasone destabilizes Cox-2 mRNA by inhibiting p38 function. Here we demonstrate that this effect is phosphatase dependent. Furthermore, in HeLa cells dexamethasone induced the sustained expression of mitogen-activated protein kinase phosphatase 1 (MKP-1), a potent inhibitor of p38 function. The inhibiti...

  17. Protein phosphatases active on acetyl-CoA carboxylase phosphorylated by casein kinase I, casein kinase II and the cAMP-dependent protein kinase

    The protein phosphatases in rat liver cytosol, active on rat liver acetyl-CoA carboxylase (ACC) phosphorylated by casein kinase I, casein kinase II and the cAMP-dependent protein kinase, have been partially purified by anion-exchange and gel filtration chromatography. The major phosphatase activities against all three substrates copurify through fractionation and appear to be identical to protein phosphatases 2A1 and 2A2. No unique protein phosphatase active on 32P-ACC phosphorylated by the casein kinases was identified

  18. Protein-tyrosine phosphatase activity regulates osteoclast formation and function: inhibition by alendronate.

    Schmidt, A.; Rutledge, S J; Endo, N; Opas, E E; Tanaka, H; Wesolowski, G.; Leu, C T; Huang, Z; Ramachandaran, C; Rodan, S B; Rodan, G A

    1996-01-01

    Alendronate (ALN), an aminobisphosphonate used in the treatment of osteoporosis, is a potent inhibitor of bone resorption. Its molecular target is still unknown. This study examines the effects of ALN on the activity of osteoclast protein-tyrosine phosphatase (PTP; protein-tyrosine-phosphate phosphohydrolase, EC 3.1.3.48), called PTPepsilon. Using osteoclast-like cells generated by coculturing mouse bone marrow cells with mouse calvaria osteoblasts, we found by molecular cloning and RNA blot ...

  19. Crystallization and preliminary X-ray diffraction analysis of rat protein tyrosine phosphatase η

    Matozo, Huita C.; Nascimento, Alessandro S.; Santos, Maria A. M. [Instituto de Física de São Carlos, Departamento de Física e Informática, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CEP 13566-590 São Carlos, SP (Brazil); Iuliano, Rodolfo [Dipartimento di Medicina Sperimentale e Clinica, Facoltà di Medicina e Chirurgia, Università di Catanzaro, 88100 Catanzaro (Italy); Fusco, Alfredo [Dipartimento di Biologia e Patologia Cellulare e Molecolare, c/o Instituto di Endocrinologia ed Oncologia Sperimentale del CNR, Facolta di Medicina e Chirurgia, Università degli Studi di Napoli ‘Federico II’, Via Pansini 5, 80131 Naples (Italy); NOGEC (Naples Oncogenomocs Center)-CEINGE, Biotecnologie Avanzate, Via Comunale Margherita 482, 80145 Naples (Italy); Polikarpov, Igor, E-mail: ipolikarpov@if.sc.usp.br [Instituto de Física de São Carlos, Departamento de Física e Informática, Universidade de São Paulo, Avenida Trabalhador São Carlense 400, CEP 13566-590 São Carlos, SP (Brazil); Laboratório Nacional de Luz Síncrotron, Campinas, SP (Brazil)

    2006-09-01

    In this study, the catalytic domain of rat protein tyrosine phosphatase η was produced in Escherichia coli in soluble form and purified to homogeneity. Crystals were obtained by the hanging-drop vapour-diffusion method. The rat protein tyrosine phosphatase η (rPTPη) is a cysteine-dependent phosphatase which hydrolyzes phosphoester bonds in proteins and other molecules. rPTPη and its human homologue DEP-1 are involved in neoplastic transformations. Thus, expression of the protein is reduced in all oncogene-transformed thyroid cell lines and is absent in highly malignant thyroid cells. Moreover, consistent with the suggested tumour suppression role of PTPη, inhibition of the tumorigenic process occurs after its exogenous reconstitution, suggesting that PTPη might be important for gene therapy of cancers. In this study, the catalytic domain of rPTPη was produced in Escherichia coli in soluble form and purified to homogeneity. Crystals were obtained by the hanging-drop vapour-diffusion method. Diffraction data were collected to 1.87 Å resolution. The crystal belongs to space group P2{sub 1}2{sub 1}2{sub 1}, with unit-cell parameters a = 46.46, b = 63.07, c = 111.64 Å, and contains one molecule per asymmetric unit.

  20. Structural Basis for the Catalytic Activity of Human Serine/Threonine Protein Phosphatase-5

    Swingle, M. R.; Honkanen, R.; Ciszak, E. M.

    2004-01-01

    Serinehhreonine protein phosphatase-5 (PP5) affects many signaling networks that regulate cell growth and cellular responses to stress. Here we report the crystal structure of the PP5 catalytic domain (PP5c) at a resolution of 1.6 A. From this structure we resolved the mechanism for PP5-mediated hydrolysis of phosphoprotein substrates, which requires the precise positioning of two metal ions within a con served Aspn-271-M(sub 1):M(sub 2)-W(sup 1)-His-427-His-304-Asp-274 catalytic motif. The structure of PPSc provides a structural basis for explaining the exceptional catalytic proficiency of protein phosphatases, which are among the most powerful known catalysts. Resolution of the entire C-terminus revealed a novel subdomain, and the structure of the PP5c should also aid development of type-specific inhibitors.

  1. Structural Basis for the Catalytic Activity of Human SER/THR Protein Phosphatase-5

    Swingle, M. R.; Honkanen, R.; Ciszak, E.

    2004-01-01

    Serinekhreonine protein phosphatase-5 (PP5) affects many signaling networks that regulate cell growth. Here we report the 1.6 Angstrom resolution crystal structure of PP5 catalytic domain with metal and phosphate ions in the active site. The structure reveals a mechanism for PPS-mediated catalysis that requires the precise positioning of two metal ions within a conserved Asp(sup 271)-M(sub 1),-M(sub 2)-His(sup 427)-W(sup 2)-His(sup 304)-Asp(sup 274) catalytic motif, and provides a structural basis for the exceptional catalytic proficiency of protein phosphatases placing them among the most powerful catalysts. Resolution of the entire C-terminus revealed a novel subdomain, and the structure of PP5 should aid development of specific inhibitors.

  2. Acrylamide gel electrophoresis of proteins, acid phosphatases and RN-ases from three potato varieties

    A. Kubicz

    2015-05-01

    Full Text Available Studies on variety differences in the protein and acid phosphatase patterns as well as ribunuclease activity distribution were carried out by disc electrophoresis on saline extracts of three varieties of the potato Solanum tuberosum (L.. The protein bands varied in number, position and relative abundance. One main zone of the acid phosphatase activity was detected consisting of 2-3 electrophoretically different bands. Variety differences were concerned with the number and relative abundance of these bands. RNase activity was detected in 4 main zones, in some of them additional subbands were visible. Differences between the three examined varieties were reflected in the occurence of the particular activity zones or their subbands.

  3. Antioxidant effects of whey protein on muscle C2C12 cells.

    Kerasioti, Efthalia; Stagos, Dimitrios; Priftis, Alexandros; Aivazidis, Stefanos; Tsatsakis, Aristidis M; Hayes, A Wallace; Kouretas, Demetrios

    2014-07-15

    In the present study, the in vitro scavenging activity of sheep whey protein against free radicals, as well as its reducing power were determined and compared with that of beef protein, soy protein and cow whey protein. Moreover, the possible protective effects of sheep whey protein from tert-butyl hydroperoxide (tBHP)-induced oxidative stress in muscle C2C12 cells were determined by assessing oxidative stress markers by flow cytometry and spectrophotometry. The results showed that sheep whey protein scavenged DPPH, ABTS(+) and OH radicals with IC50 values of 3.1, 4.1 and 1.8 mg of protein/ml. Moreover, the reducing power activity assessed with potassium ferricyanide of sheep whey protein was 1.3mg/ml. As regards to the antioxidant effects in muscle cell line, sheep whey protein at 0.78, 1.56, 3.12 and 6.24 mg of protein/ml increased GSH levels up to 138%, lowered TBARS levels up to 25% and decreased ROS levels up to 41.4%. PMID:24594185

  4. The SAP, a new family of proteins, associate and function positively with the SIT4 phosphatase.

    Luke, M M; Della Seta, F; Di Como, C J; Sugimoto, H; Kobayashi, R.; Arndt, K T

    1996-01-01

    SIT4 is the catalytic subunit of a type 2A-related protein phosphatase in Saccharomyces cerevisiae that is required for G1 cyclin transcription and for bud formation. SIT4 associates with several high-molecular-mass proteins in a cell cycle-dependent fashion. We purified two SIT4-associated proteins, SAP155 and SAP190, and cloned the corresponding genes. By sequence homology, we isolated two additional SAP genes, SAP185 and SAP4. Through such an association is not yet proven for SAP4, each of...

  5. Immunohistochemical Analysis of IA-2 Family of Protein Tyrosine Phosphatases in Rat Gastrointestinal Endocrine Cells

    Gomi, Hiroshi; Kubota-Murata, Chisato; Yasui, Tadashi; Tsukise, Azuma; Torii, Seiji

    2013-01-01

    Islet-associated protein–2 (IA-2) and IA-2β (also known as phogrin) are unique neuroendocrine-specific protein tyrosine phosphatases (PTPs). The IA-2 family of PTPs was originally identified from insulinoma cells and discovered to be major autoantigens in type 1 diabetes. Despite its expression in the neural and canonical endocrine tissues, data on expression of the IA-2 family of PTPs in gastrointestinal endocrine cells (GECs) are limited. Therefore, we immunohistochemically investigated the...

  6. The role for protein tyrosine phosphatases in regulating the immune system: implications for chronic intestinal inflammation

    Spalinger, Marianne R.; MCCOLE, DECLAN F.; Rogler, Gerhard; Scharl, Michael

    2015-01-01

    Current hypothesis suggests that genetic, immunological and bacterial factors contribute essentially to the pathogenesis of inflammatory bowel disease (IBD). Variations within the gene loci encoding protein tyrosine phosphatases (PTPs) have been associated with the onset of IBD. PTPs modulate the activity of their substrates by dephosphorylation of tyrosine residues and are critical for the regulation of fundamental cellular signalling processes.Evidence emerges that expression levels of PTPN...

  7. Protein tyrosine phosphatase non-receptor type 2 and inflammatory bowel disease

    Spalinger, Marianne R.; MCCOLE, DECLAN F.; Rogler, Gerhard; Scharl, Michael

    2016-01-01

    Genome wide association studies have associated single nucleotide polymorphisms within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) with the onset of inflammatory bowel disease (IBD) and other inflammatory disorders. Expression of PTPN2 is enhanced in actively inflamed intestinal tissue featuring a marked up-regulation in intestinal epithelial cells. PTPN2 deficient mice suffer from severe intestinal and systemic inflammation and display aberrant innate and...

  8. Role of protein tyrosine phosphatases in regulating the immune system: implications for chronic intestinal inflammation

    Spalinger, Marianne R.; MCCOLE, DECLAN F.; Rogler, Gerhard; Scharl, Michael

    2015-01-01

    Current hypothesis suggests that genetic, immunological, and bacterial factors contribute essentially to the pathogenesis of inflammatory bowel disease. Variations within the gene loci encoding protein tyrosine phosphatases (PTPs) have been associated with the onset of inflammatory bowel disease. PTPs modulate the activity of their substrates by dephosphorylation of tyrosine residues and are critical for the regulation of fundamental cellular signaling processes. Evidence emerges that express...

  9. Protein Phosphatase 1 Recruitment by Rif1 Regulates DNA Replication Origin Firing by Counteracting DDK Activity

    Anoushka Davé; Carol Cooley; Mansi Garg; Alessandro Bianchi

    2014-01-01

    Summary The firing of eukaryotic origins of DNA replication requires CDK and DDK kinase activities. DDK, in particular, is involved in setting the temporal program of origin activation, a conserved feature of eukaryotes. Rif1, originally identified as a telomeric protein, was recently implicated in specifying replication timing in yeast and mammals. We show that this function of Rif1 depends on its interaction with PP1 phosphatases. Mutations of two PP1 docking motifs in Rif1 lead to early re...

  10. Relevance of amyloid precursor-like protein 2 C-terminal fragments in pancreatic cancer cells

    PETERS, HALEY L.; Tuli, Amit; Wang, Xiaojian; Liu, Cuiling; Pan, Zenggang; Ouellette, Michel M.; Hollingsworth, Michael A.; MacDonald, Richard G.; Solheim, Joyce C.

    2012-01-01

    In some cellular systems, particularly neurons, amyloid precursor-like protein 2 (APLP2), and its highly homologous family member amyloid precursor protein (APP), have been linked to cellular growth. APLP2 and APP undergo regulated intramembrane proteolysis to produce C-terminal fragments. In this study, we found comprehensive expression of APLP2 C-terminal fragments in a panel of pancreatic cancer cell lines; however, APP C-terminal fragments were notably limited to the BxPC3 cell line. Exte...

  11. Glc7/Protein Phosphatase 1 Regulatory Subunits Can Oppose the Ipl1/Aurora Protein Kinase by Redistributing Glc7

    Pinsky, Benjamin A.; Kotwaliwale, Chitra V.; Tatsutani, Sean Y.; Breed, Christopher A.; Biggins, Sue

    2006-01-01

    Faithful chromosome segregation depends on the opposing activities of the budding yeast Glc7/PP1 protein phosphatase and Ipl1/Aurora protein kinase. We explored the relationship between Glc7 and Ipl1 and found that the phosphorylation of the Ipl1 substrate, Dam1, was altered by decreased Glc7 activity, whereas Ipl1 levels, localization, and kinase activity were not. These data strongly suggest that Glc7 ensures accurate chromosome segregation by dephosphorylating Ipl1 targets rather than regu...

  12. Activation of SPS from darkened spinach leaves by an endogenous protein phosphatase

    Sucrose-phosphate synthase from darkened spinach leaves has a low activation state but can undergo a time-dependent activation in desalted leaf extracts that is inhibited by Pi, molybdate, okadaic acid and vanadate, but stimulated by fluoride. SPS labeled in vivo with [32P]Pi in excised leaves in the dark loses incorporated 32P with time when extracts are incubated at 25 degree C. This loss is largely prevented by vanadate, suggesting that an endogenous protein phosphatase can use SPS as substrate. Changes in phosphorylation state are closely paralleled by changes in SPS activation state. The spontaneous activation achieved in the extracts can be reversed by addition of 2 mM MgATP. Feeding okadaic acid to darkened leaves prevents light activation of SPS suggesting that the endogenous protein phosphatase is similar to the type-1 enzyme of animal tissues. Overall, the results are consistent with the notion that light activation of SPS involves dephosphorylation of inhibitory phosphorylation site(s). Regulation of the protein phosphatase by Pi may be of physiological significance

  13. A novel role for Niemann-Pick disease type 2C protein in papillae formation.

    Masahiro Sugawara

    Full Text Available BACKGROUND: Despite the presence of papillary structures and papillary tumors in humans, the mechanism of papillae formation is unknown. We describe herein a novel role for Niemann-Pick disease type 2C (NPC2 protein, a cholesterol binding protein in the lysosome, in papillae formation. METHODOLOGY/PRINCIPAL FINDING: We examined NPC2 protein expression in surgical samples of papillary tissues by immunohistochemical stain, and all papillary tissues expressed NPC2 protein in the epithelium. To examine our hypothesis of NPC2 protein-mediated papillae formation, we carried out xenograft experiments using wild H460 cells (large cell lung carcinoma cell line that constitutively expressed abundant NPC2 protein and NPC2 protein-depleted H460 cells by NPC2 shRNA. The xenografts of wild H460 cells and empty shRNA vector cells showed distinct papillae formation, whereas NPC2 protein-depleted H460 cells displayed markedly reduced or no papillae. Since all papillary tissues have open spaces we examined whether NPC2 protein might also contribute to the creation of open spaces. The TUNEL assay in the xenografts of wild and empty shRNA vector H460 cells showed massive cell death, and NPC2 protein-depleted cells displayed minimal cell death. Measurement of caspase 3/7 activities in cultured H460 cells supported NPC2 protein-mediated apoptotic cell death. The presence of excess NPC2 protein, however, did not always produce papillae as seen in the xenografts of CHO cells that were stably transfected with NPC2. CONCLUSIONS/SIGNIFICANCE: The NPC2 protein of certain cells forms papillae coupled with apoptosis that creates open space. This protein may have future applications to modulate papillae formation and papillary growth in tumor tissues.

  14. INHIBITION OF PROTEIN TYROSINE PHOSPHATASE ACTIVITY MEDIATES EPIDERMAL GROWTH FACTOR RECEPTOR SIGNALING IN HUMAN AIRWAY EPITHELIAL CELLS

    Epidemiological studies have implicated zinc in the toxicity of ambient particulate matter (PM) inhalation. We previously showed that exposure to metal-laden PM inhibits protein tyrosine phosphatase (PTP) activity in human primary bronchial epithelial cells (HAEC) and leads t...

  15. Pyruvate dehydrogenase/sub b/ phosphatase inhibition by NADH and dihydrolipoamide along with effects of and capacity for binding the phosphatase to the bovine kidney transacetylase-protein X subcomplex

    NADH inhibits PDH/sub b/ phosphatase activity when 32P-PDH is associated with the intact complex but not when 32P-PDH is prepared free of other components of the complex. Addition of the transacetylase-protein X (E2-X) subcomplex both activated the phosphatase and restored NADH inhibition. Low levels of dihydrolipoyl dehydrogenase associated with the subcomplex might be required for NADH inhibition. Dihydrolipoamide gave inhibition of the phosphatase equivalent to NADH and the combination did not give additional inhibition suggesting a common mechanism. Pretreatment of phosphorylated complex and phosphatase with 2.0 mM dithiothreitol nearly eliminated inhibition of the phosphatase by NADH or dihydrolipoamide. Strong arsenite inhibition of phosphatase activity occurred only in the presence of NADH suggesting modification of thiols reduced by NADH can alter phosphatase activity. Only about 6 molecules of purified phosphatase could be activated by 1 molecule of E2-X subcomplex (initial velocities measured in 15s period). Since that corresponded to the number of protein X rather than E2 subunits, protein X may contribute to the Ca2+-dependent binding of the phosphatase. Since protein X also contains a lipoyl moiety, it may also contribute to NADH inhibition of the phosphatase

  16. Dephosphorylation specificities of protein phosphatase for cardiac troponin I, troponin T, and sites within troponin T

    2006-03-01

    Full Text Available Protein dephosphorylation by protein phosphatase 1 (PP1, acting in concert with protein kinase C (PKC and protein kinase A (PKA, is a pivotal regulatory mechanism of protein phosphorylation. Isolated rat cardiac myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 were used in determining dephosphorylation specificities, Ca2+-stimulated Mg2+ATPase activities, and Ca2+ sensitivities. In reconstituted troponin (Tn complex, PP1 displayed distinct substrate specificity in dephosphorylation of TnT preferentially to TnI, in vitro. In situ phosphorylation of cardiomyocytes with calyculin A, a protein phosphatase inhibitor, resulted in an increase in the phosphorylation stiochiometry of TnT (0.3 to 0.5 (67%, TnI (2.6 to 3.6 (38%, and MLC2 (0.4 to 1.7 (325%. These results further confirmed that though MLC2 is the preferred target substrate for protein phosphatase in the thick filament, the Tn complex (TnI and TnT from thin filament and C-protein in the thick filament are also protein phosphatase substrates. Our in vitro dephosphorylation experiments revealed that while PP1 differentially dephosphorylated within TnT at multiple sites, TnI was uniformly dephosphorylated. Phosphopeptide maps from the in vitro experiments show that TnT phosphopeptides at spots 4A and 4B are much more resistant to PP1 dephosphorylation than other TnT phosphopeptides. Mg2+ATPase assays of myofibrils phosphorylated by PKC/PKA and dephosphorylated by PP1 delineated that while PKC and PKA phosphorylation decreased the Ca2+-stimulated Mg2+ATPase activities, dephosphorylation antagonistically restored it. PKC and PKA phosphorylation decreased Ca2+ sensitivity to 3.6 µM and 5.0 µM respectively. However, dephosphorylation restored the Mg2+ATPase activity of PKC (99% and PKA (95%, along with the Ca2+ sensitivities (3.3 µM and 3.0 µM, respectively.

  17. Identification of a human src homology 2-containing protein-tyrosine-phosphatase: a putative homolog of Drosophila corkscrew.

    Freeman, R. M.; Plutzky, J; Neel, B G

    1992-01-01

    src homology 2 (SH2) domains direct binding to specific phosphotyrosyl proteins. Recently, SH2-containing protein-tyrosine-phosphatases (PTPs) were identified. Using degenerate oligonucleotides and the PCR, we have cloned a cDNA for an additional PTP, SH-PTP2, which contains two SH2 domains and is expressed ubiquitously. When expressed in Escherichia coli, SH-PTP2 displays tyrosine-specific phosphatase activity. Strong sequence similarity between SH-PTP2 and the Drosophila gene corkscrew (csw...

  18. Reversible oxidation of phosphatase and tensin homolog (PTEN) alters its interactions with signaling and regulatory proteins.

    Verrastro, Ivan; Tveen-Jensen, Karina; Woscholski, Rudiger; Spickett, Corinne M; Pitt, Andrew R

    2016-01-01

    Phosphatase and tensin homolog (PTEN) is involved in a number of different cellular processes including metabolism, apoptosis, cell proliferation and survival. It is a redox-sensitive dual-specificity protein phosphatase that acts as a tumor suppressor by negatively regulating the PI3K/Akt pathway. While direct evidence of redox regulation of PTEN downstream signaling has been reported, the effect of PTEN redox status on its protein-protein interactions is poorly understood. PTEN-GST in its reduced and a DTT-reversible H2O2-oxidized form was immobilized on a glutathione-sepharose support and incubated with cell lysate to capture interacting proteins. Captured proteins were analyzed by LC-MSMS and comparatively quantified using label-free methods. 97 Potential protein interactors were identified, including a significant number that are novel. The abundance of fourteen interactors was found to vary significantly with the redox status of PTEN. Altered binding to PTEN was confirmed by affinity pull-down and Western blotting for Prdx1, Trx, and Anxa2, while DDB1 was validated as a novel interactor with unaltered binding. These results suggest that the redox status of PTEN causes a functional variation in the PTEN interactome. The resin capture method developed had distinct advantages in that the redox status of PTEN could be directly controlled and measured. PMID:26561776

  19. Syndecan-2 is a novel ligand for the protein tyrosine phosphatase receptor CD148

    Whiteford, James R; Xian, Xiaojie; Chaussade, Claire; Vanhaesebroeck, Bart; Nourshargh, Sussan; Couchman, John R

    2011-01-01

    Syndecan-2 is a heparan sulfate proteoglycan that has a cell adhesion regulatory domain contained within its extracellular core protein. Cell adhesion to the syndecan-2 extracellular domain (S2ED) is ß1 integrin dependent; however, syndecan-2 is not an integrin ligand. Here the protein tyrosine...... phosphatase receptor CD148 is shown to be a key intermediary in cell adhesion to S2ED, with downstream ß1 integrin-mediated adhesion and cytoskeletal organization. We show that S2ED is a novel ligand for CD148 and identify the region proximal to the transmembrane domain of syndecan-2 as the site of...

  20. Epidermal growth factor stimulates substrate-selective protein-tyrosine-phosphatase activity.

    Hernández-Sotomayor, S M; Arteaga, C L; Soler, C. (Carlos); Carpenter, G

    1993-01-01

    This study investigates the regulation of protein-tyrosine-phosphatase (PTPase; EC 3.1.3.48) activity by epidermal growth factor (EGF). Cytosol from EGF-treated A-431 human epidermoid carcinoma cells was used as a source of PTPase activity, and tyrosine-phosphorylated ErbB2, EGF receptor, phospholipase C-gamma 1, and the Ras GTPase-activating protein were used as substrates to monitor PTPase activity. EGF stimulated PTPase activity that was selective toward these substrates, as it dephosphory...

  1. Expression of a Gibberellin-Induced Leucine-Rich Repeat Receptor-Like Protein Kinase in Deepwater Rice and Its Interaction with Kinase-Associated Protein Phosphatase1

    van der Knaap, Esther; Song, Wen-Yuan; Ruan, De-Ling; Sauter, Margret; Ronald, Pamela C.; Kende, Hans

    1999-01-01

    We identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK (O. sativa transmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMK was especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active, autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of a kinase-associated type 2C protein phosphatase (OsKAPP) was cloned. KAPPs are putative downstream components in kinase-mediated signal transduction pathways. The kinase interaction domain of OsKAPP was phosphorylated in vitro by the kinase domain of OsTMK. RNA gel-blot analysis indicated that the expression of OsTMK and OsKAPP was similar in different tissues of the rice plant. In protein-binding assays, OsKAPP interacted with a receptor-like protein kinase, RLK5 of Arabidopsis, but not with the protein kinase domains of the rice and maize receptor-like protein kinases Xa21 and ZmPK1, respectively. PMID:10364408

  2. Expression of a gibberellin-induced leucine-rich repeat receptor-like protein kinase in deepwater rice and its interaction with kinase-associated protein phosphatase

    Knaap, E. van der; Sauter, M.; Kende, H. (Michigan State Univ., East Lansing, MI (United States). DOE Plant Research Lab.); Song, W.Y.; Ruan, D.L.; Ronald, P.C. (Univ. of California, Davis, CA (United States). Dept. of Plant Pathology)

    1999-06-01

    The authors identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK (O. sativa transmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMK was especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of a kinase-associated type 2C protein phosphatase (OsKAPP) was cloned. KAPPs are putative downstream components in kinase-mediated signal transduction pathways. The kinase interaction domain of OsKAPP was phosphorylated in vitro by the kinase domain of OsTMK. RNA gel-blot analysis indicated that the expression of OsTMK and OsKAPP was similar in different tissues of the rice plant. In protein-binding assays, OsKAPP interacted with a receptor-like protein kinase, RLK5 of Arabidopsis, but not with the protein kinase domains of the rice and maize receptor-like protein kinases Xa21 and ZmPK1, respectively.

  3. Carboxyl-terminal receptor domains control the differential dephosphorylation of somatostatin receptors by protein phosphatase 1 isoforms.

    Andreas Lehmann

    Full Text Available We have recently identified protein phosphatase 1β (PP1β as G protein-coupled receptor (GPCR phosphatase for the sst2 somatostatin receptor using siRNA knockdown screening. By contrast, for the sst5 somatostatin receptor we identified protein phosphatase 1γ (PP1γ as GPCR phosphatase using the same approach. We have also shown that sst2 and sst5 receptors differ substantially in the temporal dynamics of their dephosphorylation and trafficking patterns. Whereas dephosphorylation and recycling of the sst2 receptor requires extended time periods of ∼30 min, dephosphorylation and recycling of the sst5 receptor is completed in less than 10 min. Here, we examined which receptor domains determine the selection of phosphatases for receptor dephosphorylation. We found that generation of tail-swap mutants between sst2 and sst5 was required and sufficient to reverse the patterns of dephosphorylation and trafficking of these two receptors. In fact, siRNA knockdown confirmed that the sst5 receptor carrying the sst2 tail is predominantly dephosphorylated by PP1β, whereas the sst2 receptor carrying the sst5 tail is predominantly dephosphorylated by PP1γ. Thus, the GPCR phosphatase responsible for dephosphorylation of individual somatostatin receptor subtypes is primarily determined by their different carboxyl-terminal receptor domains. This phosphatase specificity has in turn profound consequences for the dephosphorylation dynamics and trafficking patterns of GPCRs.

  4. Physical association of GPR54 C-terminal with protein phosphatase 2A

    KiSS1 was discovered as a metastasis suppressor gene and subsequently found to encode kisspeptins (KP), ligands for a G protein coupled receptor (GPCR), GPR54. This ligand-receptor pair was later shown to play a critical role in the neuro-endocrine regulation of puberty. The C-terminal cytoplasmic (C-ter) domain of GPR54 contains a segment rich in proline and arginine residues that corresponds to the primary structure of four overlapping SH3 binding motifs. Yeast two hybrid experiments identified the catalytic subunit of protein phosphatase 2A (PP2A-C) as an interacting protein. Pull-down experiments with GST fusion proteins containing the GPR54 C-ter confirmed binding to PP2A-C in cell lysates and these complexes contained phosphatase activity. The proline arginine rich segment is necessary for these interactions. The GPR54 C-ter bound directly to purified recombinant PP2A-C, indicating the GPR54 C-ter may form complexes involving the catalytic subunit of PP2A that regulate phosphorylation of critical signaling intermediates.

  5. Water molecule network and active site flexibility of apo protein tyrosine phosphatase 1B

    Pedersen, A.K.; Peters, Günther H.J.; Møller, K.B.;

    2004-01-01

    Protein tyrosine phosphatase 1B (PTP1B) plays a key role as a negative regulator of insulin and leptin signalling and is therefore considered to be an important molecular target for the treatment of type 2 diabetes and obesity. Detailed structural information about the structure of PTP1B, including...... the conformation and flexibility of active-site residues as well as the water-molecule network, is a key issue in understanding ligand binding and enzyme kinetics and in structure-based drug design. A 1.95 Angstrom apo PTP1B structure has been obtained, showing four highly coordinated water molecules...

  6. A novel protein tyrosine phosphatase 1B inhibitor from Tinospora sinensis

    Prasoon Gupta; Upasana Sharma; Gupta, Praveen K.; Rakesh Maurya

    2012-01-01

    Bioassay-directed fractionation led to the identification of a new compound, 4-hydroxy-heptadec-6-enoic acid ethyl ester (1) together with three known compounds (2-4) from Tinospora sinensis. The structure of 1 was determined by analysis of spectroscopic data. The isolated compounds were evaluated for their protein tyrosine phosphatase 1B (PTP1B) inhibitory activity. Compounds 1 and 2 displayed significant inhibitory activity with IC 50 values 61.1 and 74.2 μM, respectively

  7. Protein phosphatase 2A (PP2A) regulates interleukin-4-mediated STAT6 signaling

    Woetmann, Anders; Brockdorff, Johannes; Lovato, Paola;

    2002-01-01

    Interleukin-4 (IL-4) plays a pivotal role in the induction and maintenance of allergy by promoting Th2 differentiation and B cell isotype switching to IgE. Studies on STAT6-deficient mice have demonstrated the essential role of STAT6 in mediating the biological functions of IL-4. IL-4 induces...... of protein phosphatase 2A (PP2A) induces serine phosphorylation of STAT6 and severely inhibits DNA binding of STAT6. In contrast, IL-4-induced tyrosine phosphorylation of Janus kinase-1 and STAT6 is not affected, suggesting that PP2A acts downstream of Janus kinases in IL-4 signaling. In conclusion, we...

  8. In vitro characterization of the Bacillus subtilis protein tyrosine phosphatase YwqE

    Mijakovic, Ivan; Musumeci, Lucia; Tautz, Lutz;

    2005-01-01

    Both gram-negative and gram-positive bacteria possess protein tyrosine phosphatases (PTPs) with a catalytic Cys residue. In addition, many gram-positive bacteria have acquired a new family of PTPs, whose first characterized member was CpsB from Streptococcus pneumoniae. Bacillus subtilis contains......, we characterize YwqE, compare the activities of the three B. subtilis PTPs (YwqE, YwlE, and YfkJ), and demonstrate that the two B. subtilis class II PTPs do not dephosphorylate the physiological substrates of YwqE....

  9. A Mechanistic Study of Protein Phosphatase-1 (PP1), A Catalytically Promiscuous Enzyme

    McWhirter, Claire; Lund, Elizabeth A.; Eric A Tanifum; Feng, Guoqiang; Sheikh, Qaiser; Hengge, Alvan C.; Williams, Nicholas H

    2008-01-01

    The reaction catalyzed by the protein phosphatase-1 (PP1) has been examined by linear free energy relationships and kinetic isotope effects. With the substrate 4-nitrophenyl phosphate (4NPP), the reaction exhibits a bell-shaped pH-rate profile for kcat/KM indicative of catalysis by both acidic and basic residues, with kinetic pKas of 6.0 and 7.2. The enzymatic hydrolysis of a series of aryl monoester substrates yields a Brønsted βlg of -0.32, considerably less negative than that of the uncata...

  10. Protein Phosphatase 2A Interacts with and Directly Dephosphorylates RelA*

    Yang, Jinming; Fan, Guo-Huang; Wadzinski, Brian E.; Sakurai, Hiroaki; Richmond, Ann

    2001-01-01

    Nuclear factor-κB (NF-κB)/Rel transcription factors are key regulators of a variety of genes involved in inflammatory responses, growth, differentiation, apoptosis, and development. There are increasing lines of evidence that NF-κB/Rel activity is controlled to a great extent by its phosphorylation state. In this study, we demonstrated that RelA physically associated with protein phosphatase 2A (PP2A) subunit A (PR65). Both the N- and C-terminal regions of RelA were responsible for the PP2A b...

  11. Mitogen-activated Protein Kinase Phosphatase (Mkp)-1 Protects Mice against Acetaminophen-induced Hepatic Injury

    Wancket, Lyn M.; Meng, Xiaomei; Rogers, Lynette K.; Liu, Yusen

    2012-01-01

    c-Jun N-terminal kinase (JNK) activation promotes hepatocyte death during acetaminophen overdose, a common cause of drug-induced liver failure. While mitogen-activated protein kinase (MAPK) phosphatase (Mkp)-1 is a critical negative regulator of JNK MAPK, little is known about the role of Mkp-1 during hepatotoxicity. In this study, we evaluated the role of Mkp-1 during acute acetaminophen toxicity. Mkp-1+/+ and Mkp-1−/− mice were dosed ip with vehicle or acetaminophen at 300 mg/kg (for mechan...

  12. Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A

    Janssens Veerle; Goris Jozef; Louis Justin V; Zwaenepoel Karen

    2008-01-01

    Abstract Background Protein phosphatase 2A (PP2A) is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specifici...

  13. Effect of gamma-irradiation on nucleic acids, proteins, respiration and phosphatase activity of carrot callus cultures

    Callus tissue cultures were subjected to 60Co qamma irradiation at 0.5 Krad and analysed for nucleic acids, proteins, respiration rate and phosphatase activity on 0, 10, 20 and 30 days. The RNA contents and respiratory rates were enhanced as a result of irradiation. The RNA contents were reduced than their non-irradiated counterparts. The acid phosphatase activity was enhanced immediately after irradiation, declined on 10th and 20th day and more thereafter. (author)

  14. HSP105 recruits protein phosphatase 2A to dephosphorylate β-catenin.

    Yu, Nancy; Kakunda, Michael; Pham, Victoria; Lill, Jennie R; Du, Pan; Wongchenko, Matthew; Yan, Yibing; Firestein, Ron; Huang, XiaoDong

    2015-04-01

    The Wnt/β-catenin pathway causes accumulation of β-catenin in the cytoplasm and its subsequent translocation into the nucleus to initiate the transcription of the target genes. Without Wnt stimulation, β-catenin forms a complex with axin (axis inhibitor), adenomatous polyposis coli (APC), casein kinase 1α (CK1α), and glycogen synthase kinase 3β (GSK3β) and undergoes phosphorylation-dependent ubiquitination. Phosphatases, such as protein phosphatase 2A (PP2A), interestingly, also are components of this degradation complex; therefore, a balance must be reached between phosphorylation and dephosphorylation. How this balance is regulated is largely unknown. Here we show that a heat shock protein, HSP105, is a previously unidentified component of the β-catenin degradation complex. HSP105 is required for Wnt signaling, since depletion of HSP105 compromises β-catenin accumulation and target gene transcription upon Wnt stimulation. Mechanistically, HSP105 depletion disrupts the integration of PP2A into the β-catenin degradation complex, favoring the hyperphosphorylation and degradation of β-catenin. HSP105 is overexpressed in many types of tumors, correlating with increased nuclear β-catenin protein levels and Wnt target gene upregulation. Furthermore, overexpression of HSP105 is a prognostic biomarker that correlates with poor overall survival in breast cancer patients as well as melanoma patients participating in the BRIM2 clinical study. PMID:25645927

  15. Low molecular weight protein tyrosine phosphatase: Multifaceted functions of an evolutionarily conserved enzyme.

    Caselli, Anna; Paoli, Paolo; Santi, Alice; Mugnaioni, Camilla; Toti, Alessandra; Camici, Guido; Cirri, Paolo

    2016-10-01

    Originally identified as a low molecular weight acid phosphatase, LMW-PTP is actually a protein tyrosine phosphatase that acts on many phosphotyrosine-containing cellular proteins that are primarily involved in signal transduction. Differences in sequence, structure, and substrate recognition as well as in subcellular localization in different organisms enable LMW-PTP to exert many different functions. In fact, during evolution, the LMW-PTP structure adapted to perform different catalytic actions depending on the organism type. In bacteria, this enzyme is involved in the biosynthesis of group 1 and 4 capsules, but it is also a virulence factor in pathogenic strains. In yeast, LMW-PTPs dephosphorylate immunophilin Fpr3, a peptidyl-prolyl-cis-trans isomerase member of the protein chaperone family. In humans, LMW-PTP is encoded by the ACP1 gene, which is composed of three different alleles, each encoding two active enzymes produced by alternative RNA splicing. In animals, LMW-PTP dephosphorylates a number of growth factor receptors and modulates their signalling processes. The involvement of LMW-PTP in cancer progression and in insulin receptor regulation as well as its actions as a virulence factor in a number of pathogenic bacterial strains may promote the search for potent, selective and bioavailable LMW-PTP inhibitors. PMID:27421795

  16. Mutations in a new Arabidopsis cyclophilin disrupt its interaction with protein phosphatase 2A

    Jackson, K.; Soll, D.; Evans, M. L. (Principal Investigator)

    1999-01-01

    The heterotrimeric protein phosphatase 2A (PP2A) is a component of multiple signaling pathways in eukaryotes. Disruption of PP2A activity in Arabidopsis is known to alter auxin transport and growth response pathways. We demonstrated that the regulatory subunit A of an Arabidopsis PP2A interacts with a novel cyclophilin, ROC7. The gene for this cyclophilin encodes a protein that contains a unique 30-amino acid extension at the N-terminus, which distinguishes the gene product from all previously identified Arabidopsis cyclophilins. Altered forms of ROC7 cyclophilin with mutations in the conserved DENFKL domain did not bind to PP2A. Unlike protein phosphatase 2B, PP2A activity in Arabidopsis extracts was not affected by the presence of the cyclophilin-binding molecule cyclosporin. The ROC7 transcript was expressed to high levels in all tissues tested. Expression of an ROC7 antisense transcript gave rise to increased root growth. These results indicate that cyclophilin may have a role in regulating PP2A activity, by a mechanism that differs from that employed for cyclophilin regulation of PP2B.

  17. Sodium selenate retards epileptogenesis in acquired epilepsy models reversing changes in protein phosphatase 2A and hyperphosphorylated tau.

    Liu, Shi-Jie; Zheng, Ping; Wright, David K; Dezsi, Gabi; Braine, Emma; Nguyen, Thanh; Corcoran, Niall M; Johnston, Leigh A; Hovens, Christopher M; Mayo, Jamie N; Hudson, Matthew; Shultz, Sandy R; Jones, Nigel C; O'Brien, Terence J

    2016-07-01

    There are no treatments in clinical practice known to mitigate the neurobiological processes that convert a healthy brain into an epileptic one, a phenomenon known as epileptogenesis. Downregulation of protein phosphatase 2A, a protein that causes the hyperphosphorylation of tau, is implicated in neurodegenerative diseases commonly associated with epilepsy, such as Alzheimer's disease and traumatic brain injury. Here we used the protein phosphatase 2A activator sodium selenate to investigate the role of protein phosphatase 2A in three different rat models of epileptogenesis: amygdala kindling, post-kainic acid status epilepticus, and post-traumatic epilepsy. Protein phosphatase 2A activity was decreased, and tau phosphorylation increased, in epileptogenic brain regions in all three models. Continuous sodium selenate treatment mitigated epileptogenesis and prevented the biochemical abnormalities, effects which persisted after drug withdrawal. Our studies indicate that limbic epileptogenesis is associated with downregulation of protein phosphatase 2A and the hyperphosphorylation of tau, and that targeting this mechanism with sodium selenate is a potential anti-epileptogenic therapy. PMID:27289302

  18. Identification and Biochemical Characterization of Protein Phosphatase 5 from the Cantharidin-Producing Blister Beetle, Epicauta chinensis

    Xi'en Chen

    2013-12-01

    Full Text Available Protein phosphatase 5 (PP5 is a unique member of serine/threonine phosphatases which has been recognized in regulation of diverse cellular processes. A cDNA fragment encoding PP5 (EcPP5 was cloned and characterized from the cantharidin-producing blister beetle, E. chinensis. EcPP5 contains an open reading frame of 1500 bp that encodes a protein of 56.89 kDa. The deduced amino acid sequence shares 88% and 68% identities to the PP5 of Tribolium castaneum and humans, respectively. Analysis of the primary sequence shows that EcPP5 has three TPR (tetratricopeptide repeat motifs at its N-terminal region and contains a highly conserved C-terminal catalytic domain. RT-PCR reveals that EcPP5 is expressed in all developmental stages and in different tissues. The recombinant EcPP5 (rEcPP5 was produced in Escherichia coli and purified to homogeneity. The purified protein exhibited phosphatase activity towards pNPP (p-nitrophenyl phosphate and phosphopeptides, and its activity can be enhanced by arachidonic acid. In vitro inhibition study revealed that protein phosphatase inhibitors, okadaic acid, cantharidin, norcantharidin and endothall, inhibited its activity. Further, protein phosphatase activity of total soluble protein extract from E. chinensis adults could be impeded by these inhibitors suggesting there might be some mechanism to protect this beetle from being damaged by its self-produced cantharidin.

  19. PTEN Protein Phosphatase Activity Correlates with Control of Gene Expression and Invasion, a Tumor-Suppressing Phenotype, But Not with AKT Activity

    Tibarewal, P; Zilidis, G; Spinelli, L.; et al.

    2012-01-01

    The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) has a well-characterized lipid phosphatase activity and a poorly characterized protein phosphatase activity. We show that both activities are required for PTEN to inhibit cellular invasion and to mediate most of its largest effects on gene expression. PTEN appears to dephosphorylate itself at threonine 366, and mutation of this site makes lipid phosphatase activity sufficient for PTEN to inhibit invasion. We p...

  20. Structural basis for recognition of synaptic vesicle protein 2C by botulinum neurotoxin A

    Benoit, Roger M.; Frey, Daniel; Hilbert, Manuel; Kevenaar, Josta T.; Wieser, Mara M.; Stirnimann, Christian U.; McMillan, David; Ceska, Tom; Lebon, Florence; Jaussi, Rolf; Steinmetz, Michel O.; Schertler, Gebhard F. X.; Hoogenraad, Casper C.; Capitani, Guido; Kammerer, Richard A.

    2014-01-01

    Botulinum neurotoxin A (BoNT/A) belongs to the most dangerous class of bioweapons. Despite this, BoNT/A is used to treat a wide range of common medical conditions such as migraines and a variety of ocular motility and movement disorders. BoNT/A is probably best known for its use as an antiwrinkle agent in cosmetic applications (including Botox and Dysport). BoNT/A application causes long-lasting flaccid paralysis of muscles through inhibiting the release of the neurotransmitter acetylcholine by cleaving synaptosomal-associated protein 25 (SNAP-25) within presynaptic nerve terminals. Two types of BoNT/A receptor have been identified, both of which are required for BoNT/A toxicity and are therefore likely to cooperate with each other: gangliosides and members of the synaptic vesicle glycoprotein 2 (SV2) family, which are putative transporter proteins that are predicted to have 12 transmembrane domains, associate with the receptor-binding domain of the toxin. Recently, fibroblast growth factor receptor 3 (FGFR3) has also been reported to be a potential BoNT/A receptor. In SV2 proteins, the BoNT/A-binding site has been mapped to the luminal domain, but the molecular details of the interaction between BoNT/A and SV2 are unknown. Here we determined the high-resolution crystal structure of the BoNT/A receptor-binding domain (BoNT/A-RBD) in complex with the SV2C luminal domain (SV2C-LD). SV2C-LD consists of a right-handed, quadrilateral β-helix that associates with BoNT/A-RBD mainly through backbone-to-backbone interactions at open β-strand edges, in a manner that resembles the inter-strand interactions in amyloid structures. Competition experiments identified a peptide that inhibits the formation of the complex. Our findings provide a strong platform for the development of novel antitoxin agents and for the rational design of BoNT/A variants with improved therapeutic properties.

  1. Identification of a Low Molecular Weight Protein Tyrosine Phosphatase and Its Potential Physiological Substrates in Synechocystis sp. PCC 6803

    Mukhopadhyay, Archana

    2006-01-01

    The predicted protein product of open reading frame slr0328 from Synechocystis sp. PCC 6803, SynPTP, possesses significant amino acid sequence similarity with known low molecular weight protein tyrosine phosphatases (PTPs). To determine the gross functional properties of this hypothetical protein, open reading frame slr0328 was cloned, and its predicted protein product was expressed in E. coli. The recombinant protein, SynPTP, was purified by metal ion column chromatography. The catalytic act...

  2. Residue 182 influences the second step of protein-tyrosine phosphatase-mediated catalysis

    Pedersen, A.K.; Guo, X.; Møller, K.B.;

    2004-01-01

    Previous enzyme kinetic and structural studies have revealed a critical role for Asp(181) (PTP1B numbering) in PTP (protein-tyrosine phosphatase)-mediated catalysis. In the E-P (phosphoenzyme) formation step, Asp(181) functions as a general acid, while in the E-P hydrolysis step it acts as a gene......Previous enzyme kinetic and structural studies have revealed a critical role for Asp(181) (PTP1B numbering) in PTP (protein-tyrosine phosphatase)-mediated catalysis. In the E-P (phosphoenzyme) formation step, Asp(181) functions as a general acid, while in the E-P hydrolysis step it acts...... as a general base. Most of our understanding of the role of Asp(181). is derived from studies with the Yersinia PTP and the mammalian PTP1B, and to some extent also TC (T-cell)-PTP and, the related PTPalpha and PTPepsilon. The neighbouring residue 182 is a phenylalanine in these four mammalian enzymes......, in comparison with Phe(182)-PTPs, have significantly decreased k(cat) values, and to a lesser degree, decreased k(cat)/K-m values. Combined enzyme kinetic, X-ray crystallographic and molecular dynamics studies indicate that the effect of His(182) is due to interactions with Asp(181) and with Gln(262). We...

  3. Selective binding modes and allosteric inhibitory effects of lupane triterpenes on protein tyrosine phosphatase 1B.

    Jin, Tiantian; Yu, Haibo; Huang, Xu-Feng

    2016-01-01

    Protein Tyrosine Phosphatase 1B (PTP1B) has been recognized as a promising therapeutic target for treating obesity, diabetes, and certain cancers for over a decade. Previous drug design has focused on inhibitors targeting the active site of PTP1B. However, this has not been successful because the active site is positively charged and conserved among the protein tyrosine phosphatases. Therefore, it is important to develop PTP1B inhibitors with alternative inhibitory strategies. Using computational studies including molecular docking, molecular dynamics simulations, and binding free energy calculations, we found that lupane triterpenes selectively inhibited PTP1B by targeting its more hydrophobic and less conserved allosteric site. These findings were verified using two enzymatic assays. Furthermore, the cell culture studies showed that lupeol and betulinic acid inhibited the PTP1B activity stimulated by TNFα in neurons. Our study indicates that lupane triterpenes are selective PTP1B allosteric inhibitors with significant potential for treating those diseases with elevated PTP1B activity. PMID:26865097

  4. A mutation in protein phosphatase 2A regulatory subunit A affects auxin transport in Arabidopsis

    Garbers, C.; DeLong, A.; Deruere, J.; Bernasconi, P.; Soll, D.; Evans, M. L. (Principal Investigator)

    1996-01-01

    The phytohormone auxin controls processes such as cell elongation, root hair development and root branching. Tropisms, growth curvatures triggered by gravity, light and touch, are also auxin-mediated responses. Auxin is synthesized in the shoot apex and transported through the stem, but the molecular mechanism of auxin transport is not well understood. Naphthylphthalamic acid (NPA) and other inhibitors of auxin transport block tropic curvature responses and inhibit root and shoot elongation. We have isolated a novel Arabidopsis thaliana mutant designated roots curl in NPA (rcn1). Mutant seedlings exhibit altered responses to NPA in root curling and hypocotyl elongation. Auxin efflux in mutant seedlings displays increased sensitivity to NPA. The rcn1 mutation was transferred-DNA (T-DNA) tagged and sequences flanking the T-DNA insert were cloned. Analysis of the RCN1 cDNA reveals that the T-DNA insertion disrupts a gene for the regulatory A subunit of protein phosphatase 2A (PP2A-A). The RCN1 gene rescues the rcn1 mutant phenotype and also complements the temperature-sensitive phenotype of the Saccharomyces cerevisiae PP2A-A mutation, tpd3-1. These data implicate protein phosphatase 2A in the regulation of auxin transport in Arabidopsis.

  5. Negative regulation of caspase 3-cleaved PAK2 activity by protein phosphatase 1

    2008-01-01

    The p21-activated kinase 2 (PAK2) is activated by binding of small G proteins, Cdc42 and Rac, or through proteolytic cleavage by caspases or caspase-like proteases. Activation by both small G protein and caspase requires autophosphorylation at Thr-402 of PAK2. Although activation of PAK2 has been investigated for nearly a decade, the mechanism of PAK2 downregulation is unclear. In this study, we have applied the kinetic theory of substrate reaction during modification of enzyme activity to study the regulation mechanism of PAK2 activity by the catalytic subunit of protein phosphatase 1 (PP1α). On the basis of the kinetic equation of the substrate reaction during the reversible phosphorylation of PAK2, all microscopic kinetic constants for the free enzyme and enzyme-substrate(s) complexes have been determined. The results indicate that (1) PP1α can act directly on phosphorylated Thr-402 in the activation loop of PAK2 and down-regulate its kinase activity; (2) binding of the exogenous protein/peptide substrates at the active site of PAK2 decreases both the rates of PAK2 autoactivation and inactivation. The present method provides a novel approach for studying reversible phosphorylation reactions. The advantage of this method is not only its usefulness in study of substrate effects on enzyme modification but also its convenience in study of modification reaction directly involved in regulation of enzyme activity. This initial study should provide a foundation for future structural and mechanistic work of protein kinases and phosphatases.

  6. Negative regulation of caspase 3-cleaved PAK2 activity by protein phosphatase 1

    2008-01-01

    The p21-activated kinase 2 (PAK2) is activated by binding of small G proteins, Cdc42 and Rac, or through proteolytic cleavage by caspases or caspase-like proteases. Activation by both small G protein and caspase requires autophosphorylation at Thr-402 of PAK2. Although activation of PAK2 has been investigated for nearly a decade, the mechanism of PAK2 downregulation is unclear. In this study, we have applied the kinetic theory of substrate reaction during modification of enzyme activity to study the regulation mechanism of PAK2 activity by the catalytic subunit of protein phosphatase 1 (PP1α). On the basis of the kinetic equation of the substrate reaction during the reversible phosphorylation of PAK2, all microscopic kinetic constants for the free enzyme and enzyme-substrate(s) complexes have been determined. The results indicate that (1) PP1α can act directly on phosphorylated Thr-402 in the acti-vation loop of PAK2 and down-regulate its kinase activity; (2) binding of the exogenous protein/peptide substrates at the active site of PAK2 decreases both the rates of PAK2 autoactivation and inactivation. The present method provides a novel approach for studying reversible phosphorylation reactions. The advantage of this method is not only its usefulness in study of substrate effects on enzyme modifica-tion but also its convenience in study of modification reaction directly involved in regulation of enzyme activity. This initial study should provide a foundation for future structural and mechanistic work of protein kinases and phosphatases.

  7. Recent progress on the structure of Ser/Thr protein phosphatases

    WANG BaiJing; ZHANG Peng; WEI Quni

    2008-01-01

    PP1, PP2A and PP2B, belonging to the PPP family of Ser/Thr protein phosphatases, participate in regulating many important physiological processes, such as cell cycle control, regulation of cell growth and division regulation, etc. The sequence homology between them is relatively high, and ter-tiary structure is conserved. Because of the complexity of the structure of PP2A and the diversity of its regulatory subunits, its structure is less well known than those of PP1 and PP2B. The PP2A holoen-zyme consists of a heterodimeric core enzyme, comprising a scaffolding subunit and a catalytic sub-unit, as well as a variable regulatory subunit. In this study, the subunit compositions, similarities and differences between the Ser/Thr protein phsphatases structures are summarized.

  8. Disulfide bonds in the catalytic subunit of skeletal muscle protein phosphatase

    The protein phosphatase in skeletal muscle that inactivates phosphorylase and phosphorylase kinase and activates glycogen synthase is both inhibited and reversibly activated/inactivated by a heat-stable protein called inhibitor-2 (I2). This enzyme, called type-1 or MgATP-dependent protein phosphatase, has a catalytic subunit (C) of M/sub r/ = 38,000. Conversion of the inactive to the active conformer of C occurs by reaction with Mn2+ or Co2+, or by dephosphorylation of I2 bound to the C. The C active conformer is cleaved by trypsin to give a stable catalytic fragment of M/sub r/ = 33,000 which resists denaturation by 80% ethanol. This fragment of C was purified by polylysine and Sephadex chromatography to over 20,000 U/mg. After boiling the catalytic fragment of C in 0.1% dodecyl sulfate containing dithiothreitol (DTT), reaction with [14C]-iodoacetate labeled about 1 residue/molecule. However, the authors found the same extent of labeling without DTT in 6M guanidine at pH 9 and in parallel reactions that contained DTT, labeling was increased over 10-fold. The fully labeled protein migrated at M/sub r/ = 33,000 during gel electrophoresis. Chymotryptic digestion in dodecyl sulfate yielded eight major 14C peptides that were resolved by reversed-phase HPLC. The results are interpreted as evidence that C contains one free Cys residue and as many as 5 disulfide bonds. Multiple disulfides would account for the unusual stability of C and intramolecular disulfide interchange is proposed as the mechanism for conversion of the conformers

  9. Striatal-enriched protein tyrosine phosphatase modulates nociception: evidence from genetic deletion and pharmacological inhibition.

    Azkona, Garikoitz; Saavedra, Ana; Aira, Zigor; Aluja, David; Xifró, Xavier; Baguley, Tyler; Alberch, Jordi; Ellman, Jonathan A; Lombroso, Paul J; Azkue, Jon J; Pérez-Navarro, Esther

    2016-02-01

    The information from nociceptors is processed in the dorsal horn of the spinal cord by complex circuits involving excitatory and inhibitory interneurons. It is well documented that GluN2B and ERK1/2 phosphorylation contributes to central sensitization. Striatal-enriched protein tyrosine phosphatase (STEP) dephosphorylates GluN2B and ERK1/2, promoting internalization of GluN2B and inactivation of ERK1/2. The activity of STEP was modulated by genetic (STEP knockout mice) and pharmacological (recently synthesized STEP inhibitor, TC-2153) approaches. STEP(61) protein levels in the lumbar spinal cord were determined in male and female mice of different ages. Inflammatory pain was induced by complete Freund's adjuvant injection. Behavioral tests, immunoblotting, and electrophysiology were used to analyze the effect of STEP on nociception. Our results show that both genetic deletion and pharmacological inhibition of STEP induced thermal hyperalgesia and mechanical allodynia, which were accompanied by increased pGluN2B(Tyr1472) and pERK1/2(Thr202/Tyr204)levels in the lumbar spinal cord. Striatal-enriched protein tyrosine phosphatase heterozygous and knockout mice presented a similar phenotype. Furthermore, electrophysiological experiments showed that TC-2153 increased C fiber-evoked spinal field potentials. Interestingly, we found that STEP(61) protein levels in the lumbar spinal cord inversely correlated with thermal hyperalgesia associated with age and female gender in mice. Consistently, STEP knockout mice failed to show age-related thermal hyperalgesia, although gender-related differences were preserved. Moreover, in a model of inflammatory pain, hyperalgesia was associated with increased phosphorylation-mediated STEP(61) inactivation and increased pGluN2B(Tyr1472) and pERK1/2(Thr202/Tyr204)levels in the lumbar spinal cord. Collectively, the present results underscore an important role of spinal STEP activity in the modulation of nociception. PMID:26270590

  10. Genome-wide functional analysis of plasmodium protein phosphatases reveals key regulators of parasite development and differentiation

    Guttery, David S.

    2014-07-09

    Reversible protein phosphorylation regulated by kinases and phosphatases controls many cellular processes. Although essential functions for the malaria parasite kinome have been reported, the roles of most protein phosphatases (PPs) during Plasmodium development are unknown. We report a functional analysis of the Plasmodium berghei protein phosphatome, which exhibits high conservation with the P. falciparum phosphatome and comprises 30 predicted PPs with differential and distinct expression patterns during various stages of the life cycle. Gene disruption analysis of P. berghei PPs reveals that half of the genes are likely essential for asexual blood stage development, whereas six are required for sexual development/sporogony in mosquitoes. Phenotypic screening coupled with transcriptome sequencing unveiled morphological changes and altered gene expression in deletion mutants of two N-myristoylated PPs. These findings provide systematic functional analyses of PPs in Plasmodium, identify how phosphatases regulate parasite development and differentiation, and can inform the identification of drug targets for malaria. © 2014 The Authors.

  11. Energy-requiring translocation of the OmpA protein and alkaline phosphatase of Escherichia coli into inner membrane vesicles.

    Rhoads, D B; Tai, P C; Davis, B D

    1984-01-01

    In developing a reliable in vitro system for translocating bacterial proteins, we found that the least dense subfraction of the membrane of Escherichia coli was superior to the total inner membrane, both for a secreted protein (alkaline phosphatase) and for an outer membrane protein (OmpA). Compounds that eliminated the proton motive force inhibited translocation, as already observed in cells; since protein synthesis continued, the energy for translocation appears to be derived from the energ...

  12. Protein Phosphatase 1 Recruitment by Rif1 Regulates DNA Replication Origin Firing by Counteracting DDK Activity

    Anoushka Davé

    2014-04-01

    Full Text Available The firing of eukaryotic origins of DNA replication requires CDK and DDK kinase activities. DDK, in particular, is involved in setting the temporal program of origin activation, a conserved feature of eukaryotes. Rif1, originally identified as a telomeric protein, was recently implicated in specifying replication timing in yeast and mammals. We show that this function of Rif1 depends on its interaction with PP1 phosphatases. Mutations of two PP1 docking motifs in Rif1 lead to early replication of telomeres in budding yeast and misregulation of origin firing in fission yeast. Several lines of evidence indicate that Rif1/PP1 counteract DDK activity on the replicative MCM helicase. Our data suggest that the PP1/Rif1 interaction is downregulated by the phosphorylation of Rif1, most likely by CDK/DDK. These findings elucidate the mechanism of action of Rif1 in the control of DNA replication and demonstrate a role of PP1 phosphatases in the regulation of origin firing.

  13. Lentivirus-Mediated Short-Hairpin RNA Targeting Protein Phosphatase 4 Regulatory Subunit 1 Inhibits Growth in Breast Cancer

    Qi, Yuying; Hu, Tinghui; Li, Kai; Ye, Renqing; Ye, Zuodong

    2015-01-01

    Purpose Protein phosphatase 4 regulatory subunit 1 (PP4R1), as an interaction partner of the catalytic serine/threonine-protein phosphatase 4 catalytic subunit has been shown to involve in cellular processes and nuclear factor κB signaling. However, the functions of PP4R1 in human breast cancers remain unclear. This study is designed to explore the effect of PP4R1 knockdown on the biological characteristics of breast cancer cells. Methods A lentivirus-mediated short hairpin RNA (shRNA) was de...

  14. Protein-protein interactions in crystals of the human receptor-type protein tyrosine phosphatase ICA512 ectodomain.

    María E Primo

    Full Text Available ICA512 (or IA-2 is a transmembrane protein-tyrosine phosphatase located in secretory granules of neuroendocrine cells. Initially, it was identified as one of the main antigens of autoimmune diabetes. Later, it was found that during insulin secretion, the cytoplasmic domain of ICA512 is cleaved and relocated to the nucleus, where it stimulates the transcription of the insulin gene. The role of the other parts of the receptor in insulin secretion is yet to be unveiled. The structures of the intracellular pseudocatalytic and mature extracellular domains are known, but the transmembrane domain and several intracellular and extracellular parts of the receptor are poorly characterized. Moreover the overall structure of the receptor remains to be established. We started to address this issue studying by X-ray crystallography the structure of the mature ectodomain of ICA512 (ME ICA512 and variants thereof. The variants and crystallization conditions were chosen with the purpose of exploring putative association interfaces, metal binding sites and all other structural details that might help, in subsequent works, to build a model of the entire receptor. Several structural features were clarified and three main different association modes of ME ICA512 were identified. The results provide essential pieces of information for the design of new experiments aimed to assess the structure in vivo.

  15. Mechanisms underlying the inhibitory effects of arsenic compounds on protein tyrosine phosphatase (PTP)

    Arsenic binding to biomolecules is considered one of the major toxic mechanisms, which may also be related to the carcinogenic risks of arsenic in humans. At the same time, arsenic is also known to activate the phosphorylation-dependent signaling pathways including the epidermal growth factor receptor, the mitogen-activated protein kinase and insulin/insulin-like growth factor-1 pathways. These signaling pathways originate at the level of receptor tyrosine kinases whose phosphorylation status is regulated by opposing protein tyrosine phosphatase (PTP) activity. Reversible tyrosine phosphorylation, which is governed by the balanced action of protein tyrosine kinases and phosphatases, regulates important signaling pathways that are involved in the control of cell proliferation, adhesion and migration. In the present study, we have focused on the interaction of cellular PTPs with toxic trivalent arsenite (iAsIII) and its intermediate metabolites such as monomethylarsonous acid (MMAIII) and dimethylarsinous acid (DMAIII) in vitro, and then determined the arsenic binding site in PTP by the use of recombinant PTPs (e.g., PTP1B and CD45). Interestingly, the activities of PTP1B (cytoplasm-form) or CD45 (receptor-linked form) were observed to be strongly inhibited by both methylated metabolites (i.e., MMAIII and DMAIII) but not by iAsIII. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF MS) has clearly confirmed that the organic intermediate, DMAIII directly bound to the active site cysteine residue of PTP1B (e.g., Cys215), resulting in inhibition of enzyme activity. These results suggest that arsenic exposure may disturb the cellular signaling pathways through PTP inactivation. Highlights: ► This study focused on the interaction of PTPs with trivalent arsenicals in vitro. ► We for the first time confirmed that DMAIII strongly inhibited activity of PTP1B. ► DMAIII directly bound to PTP1B, resulting in inhibition of enzyme

  16. Protein phosphatase 5 is necessary for ATR-mediated DNA repair

    Kang, Yoonsung [Department of Pharmacology, DNA Repair Research Center, Chosun University School of Medicine, 375 Seosuk-Dong, Gwangju 501-759 (Korea, Republic of); Cheong, Hyang-Min [Department of Life Science, College of Natural Science, Chung-Ang University, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Lee, Jung-Hee [Department of Pharmacology, DNA Repair Research Center, Chosun University School of Medicine, 375 Seosuk-Dong, Gwangju 501-759 (Korea, Republic of); Song, Peter I. [Department of Dermatology, University of Arkansas for Medical Science, 4301 West Markham, Slot 576, Little Rock, AR 72205 (Korea, Republic of); Lee, Kwang-Ho [Department of Life Science, College of Natural Science, Chung-Ang University, 221 Heuksuk-Dong, Dongjak-Ku, Seoul 156-756 (Korea, Republic of); Kim, Sang-Yong [Division of Endocrinology, Department of Internal Medicine, Chosun University School of Medicine, 375 Seosuk-Dong, Gwangju 501-759 (Korea, Republic of); Jun, Jae Yeoul [Department of Physiology, Chosun University School of Medicine, 375 Seosuk-Dong, Gwangju 501-759 (Korea, Republic of); You, Ho Jin, E-mail: hjyou@chosun.ac.kr [Department of Pharmacology, DNA Repair Research Center, Chosun University School of Medicine, 375 Seosuk-Dong, Gwangju 501-759 (Korea, Republic of)

    2011-01-07

    Research highlights: {yields} Serine/threonine protein phosphatase 5 (PP5) has been shown to participate in ataxia telangiectasia-mutated (ATM)- and ATR (ATM- and Rad3-related)-mediated checkpoint pathways, which plays an important role in the DNA damage response and maintenance of genomic stability. {yields} However, it is not clear exactly how PP5 participates in this process. {yields} Our results indicate that PP5 is more closely related with ATR-mediated pathway than ATM-mediated pathway in DNA damage repair. -- Abstract: Several recent studies have shown that protein phosphatase 5 (PP5) participates in cell cycle arrest after DNA damage, but its roles in DNA repair have not yet been fully characterized. We investigated the roles of PP5 in the repair of ultraviolet (UV)- and neocarzinostatin (NCS)-induced DNA damage. The results of comet assays revealed different repair patterns in UV- and NCS-exposed U2OS-PS cells. PP5 is only essential for Rad3-related (ATR)-mediated DNA repair. Furthermore, the phosphorylation of 53BP1 and BRCA1, important mediators of DNA damage repair, and substrates of ATR and ATM decreased in U2OS-PS cells exposed to UV radiation. In contrast, the cell cycle arrest proteins p53, CHK1, and CHK2 were normally phosphorylated in U2OS and U2OS-PS cells exposed to UV radiation or treated with NCS. In view of these results, we suggest that PP5 plays a crucial role in ATR-mediated repair of UV-induced DNA damage.

  17. Characterization of Two Putative Protein Phosphatase Genes and Their Involvement in Phosphorus Efficiency in Phaseolus vulgari

    Cui-Yue Liang; Zhi-Jian Chen; Zhu-Fang Yao; Jiang Tian; Hong Liao

    2012-01-01

    Protein dephosphorylation mediated by protein phosphatases plays a major role in signal transduction of plant responses to environmental stresses.In this study,two putative protein phosphatases,PvPS2:1 and PvPS2:2 were identified and characterized in bean (Phaseolus vulgaris).The two PvPS2 members were found to be localized to the plasma membrane and the nucleus by transient expression of PvPS2:GFP in onion epidermal cells.Transcripts of the two PvPS2 genes were significantly increased by phosphate (Pi) starvation in the two bean genotypes,G19833 (a P-efficient genotype) and DOR364 (a P-inefficient genotype).However,G19833 exhibited higher PvPS2:1 expression levels than DOR364 in both leaves and roots during P1 starvation.Increased transcription of PvPS2:1 in response to Pi starvation was further verified through histochemical analysis of PvPS2:1 promoter fusion β-glucuronidase (GUS) in transgenic Arabidopsis plants.Analysis of PvPS2∶1 overexpression lines in bean hairy roots and Arabidopsis showed that PvS2:1 was involved in root growth and P accumulation.Furthermore,expression levels of two P(1) starvation responsive genes were upregulated and the APase activities were enhanced in the overexpressing PvPS2∶1 Arabidopsis lines.Taken together,our results strongly suggested that PvPS2∶1positively regulated plant responses to P1 starvation,and could be further targeted as a candidate gene to improve crop P efficiency.

  18. Protein phosphatase 5 is necessary for ATR-mediated DNA repair

    Research highlights: → Serine/threonine protein phosphatase 5 (PP5) has been shown to participate in ataxia telangiectasia-mutated (ATM)- and ATR (ATM- and Rad3-related)-mediated checkpoint pathways, which plays an important role in the DNA damage response and maintenance of genomic stability. → However, it is not clear exactly how PP5 participates in this process. → Our results indicate that PP5 is more closely related with ATR-mediated pathway than ATM-mediated pathway in DNA damage repair. -- Abstract: Several recent studies have shown that protein phosphatase 5 (PP5) participates in cell cycle arrest after DNA damage, but its roles in DNA repair have not yet been fully characterized. We investigated the roles of PP5 in the repair of ultraviolet (UV)- and neocarzinostatin (NCS)-induced DNA damage. The results of comet assays revealed different repair patterns in UV- and NCS-exposed U2OS-PS cells. PP5 is only essential for Rad3-related (ATR)-mediated DNA repair. Furthermore, the phosphorylation of 53BP1 and BRCA1, important mediators of DNA damage repair, and substrates of ATR and ATM decreased in U2OS-PS cells exposed to UV radiation. In contrast, the cell cycle arrest proteins p53, CHK1, and CHK2 were normally phosphorylated in U2OS and U2OS-PS cells exposed to UV radiation or treated with NCS. In view of these results, we suggest that PP5 plays a crucial role in ATR-mediated repair of UV-induced DNA damage.

  19. Regulation of human CYP2C9 expression by electrophilic stress involves activator protein 1 activation and DNA looping.

    Makia, Ngome L; Surapureddi, Sailesh; Monostory, Katalin; Prough, Russell A; Goldstein, Joyce A

    2014-08-01

    Cytochrome P450 (CYP)2C9 and CYP2C19 are important human enzymes that metabolize therapeutic drugs, environmental chemicals, and physiologically important endogenous compounds. Initial studies using primary human hepatocytes showed induction of both the CYP2C9 and CYP2C19 genes by tert-butylhydroquinone (tBHQ). As a pro-oxidant, tBHQ regulates the expression of cytoprotective genes by activation of redox-sensing transcription factors, such as the nuclear factor E2-related factor 2 (Nrf2) and members of the activator protein 1 (AP-1) family of proteins. The promoter region of CYP2C9 contains two putative AP-1 sites (TGAGTCA) at positions -2201 and -1930, which are also highly conserved in CYP2C19. The CYP2C9 promoter is activated by ectopic expression of cFos and JunD, whereas Nrf2 had no effect. Using specific kinase inhibitors for mitogen-activated protein kinase, we showed that extracellular signal-regulated kinase and Jun N-terminal kinase are essential for tBHQ-induced expression of CYP2C9. Electrophoretic mobility shift assays demonstrate that cFos distinctly interacts with the distal AP-1 site and JunD with the proximal site. Because cFos regulates target genes as heterodimers with Jun proteins, we hypothesized that DNA looping might be required to bring the distal and proximal AP-1 sites together to activate the CYP2C9 promoter. Chromosome conformation capture analyses confirmed the formation of a DNA loop in the CYP2C9 promoter, possibly allowing interaction between cFos at the distal site and JunD at the proximal site to activate CYP2C9 transcription in response to electrophiles. These results indicate that oxidative stress generated by exposure to electrophilic xenobiotics and metabolites induces the expression of CYP2C9 and CYP2C19 in human hepatocytes. PMID:24830941

  20. Foot-and-Mouth Disease Virus 2C Is a Hexameric AAA+ Protein with a Coordinated ATP Hydrolysis Mechanism

    Sweeney, Trevor; Cisnetto, Valentina; Bose, Daniel;

    2010-01-01

    Foot-and-mouth disease virus (FMDV), a positive sense, single-stranded RNA virus, causes a highly contagious disease in cloven-hoofed livestock. Like other picornaviruses, FMDV has a conserved 2C protein assigned to the superfamily 3 helicases a group of AAA+ ATPases that has a predicted N....... Unliganded 2C(34–318) exhibits concentration-dependent self-association to yield oligomeric forms, the largest of which is tetrameric. Strikingly, in the presence of ATP and RNA, FMDV 2C(34–318) containing the N207A mutation, which binds but does not hydrolyze ATP, was found to oligomerize specifically...... into hexamers. Visualization of FMDV 2C-ATP-RNA complexes by negative stain electron microscopy revealed hexameric ring structures with 6-fold symmetry that are characteristic of AAA+ ATPases. ATPase assays performed by mixing purified active and inactive 2C(34–318) subunits revealed a coordinated mechanism...

  1. Protein phosphatase 2A isotypes regulate cell surface expression of the T cell receptor

    Lauritsen, Jens Peter Holst; Menné, C; Kastrup, J;

    2001-01-01

    The mechanisms underlying T cell receptor (TCR) down-regulation have been extensively studied during the last decade. Whereas the importance of phosphorylation in this process has been established, it is less certain whether dephosphorylation plays a role in TCR down-regulation. In this study, we...... show that inhibition of the serine/threonine protein phosphatase PP2A family had a biphasic effect on TCR expression. Thus, low concentrations of PP2A inhibitors induced TCR down-regulation, whereas higher concentrations of PP2A inhibitors induced TCR up-regulation. The effect of PP2A inhibition was...... independent of phosphorylation of the CD3gamma endocytosis motif. Whereas TCR down-regulation was caused by a partial inhibition of exocytosis, TCR up-regulation was caused by an inhibition of endocytosis. The effects on exocytosis and endocytosis were not restricted to the TCR, indicating a more general...

  2. Family of receptor-linked protein tyrosine phosphatases in humans and Drosophila

    To understand the regulation of cell proliferation by tyrosine phosphorylation, characterization of protein tyrosine phosphatases is essential. The human genes LCA (leukocyte common antigen) and LAR encode putative receptor-linked PTPases. By using consensus sequence probes, two additional receptor-linked PTPase genes, DLAR and DPTP, were isolated from Drosophila melanogaster. The extra-cellular segments of both DLAR and DPTP are composed of multiple immunoglobulin-like domains and fibronectin type III-like domains. The cytoplasmic region of DLAR and DPTP, as well as human LCA and LAR, are composed of two tandemly repeated PTPase domains. PTPase activities of immunoprecipitated LCA and LAR were demonstrated by measuring the release of phosphate from a 32P-labeled [Tyr(P)]peptide. Furthermore, the cytoplasmic domains of LCA, LAR, DLAR, and DPTP, expressed in Escherichia coli, have PTPase activity. Site-directed mutagenesis showed that a conserved cysteine residue is essential for PTPase activity

  3. Cell Death Inducing Microbial Protein Phosphatase Inhibitors—Mechanisms of Action

    Rune Kleppe

    2015-10-01

    Full Text Available Okadaic acid (OA and microcystin (MC as well as several other microbial toxins like nodularin and calyculinA are known as tumor promoters as well as inducers of apoptotic cell death. Their intracellular targets are the major serine/threonine protein phosphatases. This review summarizes mechanisms believed to be responsible for the death induction and tumor promotion with focus on the interdependent production of reactive oxygen species (ROS and activation of Ca2+/calmodulin kinase II (CaM-KII. New data are presented using inhibitors of specific ROS producing enzymes to curb nodularin/MC-induced liver cell (hepatocyte death. They indicate that enzymes of the arachidonic acid pathway, notably phospholipase A2, 5-lipoxygenase, and cyclooxygenases, may be required for nodularin/MC-induced (and presumably OA-induced cell death, suggesting new ways to overcome at least some aspects of OA and MC toxicity.

  4. Expression, purification and characterization of recombinant protein tyrosine phosphatase from Thermus thermophilus HB27

    Yejing Wang; Fanguo Meng; Yingmei Zhang

    2009-01-01

    The low-molecular-weight protein tyrosine phospha-tases (PTPase) exist ubiquitously in prokaryotes and eukaryotes and play important roles in the regulation of physiological activities. We report here the expression, purification and characterization of an active and soluble PTPase from Thermus thermophilus HB27 in Escherichia coli. This PTPase has an optimum pH range of 2.8-4.8 when using p-nitrophenyl phos-phate as the substrate. The thermal inactivation results indicate a high thermal stability of this enzyme, with the optimum temperature of 75℃ for activity. It can be activated by Mn2+, Mg2+, Ca2+, Ba2+, and Ni2+, but inhibited by Zn2+, Cu2+, Cl-, and SO2-4. These results suggest that this heat-resistant PTPase may play impor-tant roles in vivo in the adaptation of the microorgan-ism to extreme temperatures and specific nutritional conditions.

  5. Quantitative phosphoproteomics reveals new roles for the protein phosphatase PP6 in mitotic cells.

    Rusin, Scott F; Schlosser, Kate A; Adamo, Mark E; Kettenbach, Arminja N

    2015-10-13

    Protein phosphorylation is an important regulatory mechanism controlling mitotic progression. Protein phosphatase 6 (PP6) is an essential enzyme with conserved roles in chromosome segregation and spindle assembly from yeast to humans. We applied a baculovirus-mediated gene silencing approach to deplete HeLa cells of the catalytic subunit of PP6 (PP6c) and analyzed changes in the phosphoproteome and proteome in mitotic cells by quantitative mass spectrometry-based proteomics. We identified 408 phosphopeptides on 272 proteins that increased and 298 phosphopeptides on 220 proteins that decreased in phosphorylation upon PP6c depletion in mitotic cells. Motif analysis of the phosphorylated sites combined with bioinformatics pathway analysis revealed previously unknown PP6c-dependent regulatory pathways. Biochemical assays demonstrated that PP6c opposed casein kinase 2-dependent phosphorylation of the condensin I subunit NCAP-G, and cellular analysis showed that depletion of PP6c resulted in defects in chromosome condensation and segregation in anaphase, consistent with dysregulation of condensin I function in the absence of PP6 activity. PMID:26462736

  6. Structural Basis for the Catalytic Activity of Human Serine/Threonine Protein Phosphatase type 5 (PP5)

    Swingle, Mark R.; Ciszak, Ewa M.; Honkanen, Richard E.

    2004-01-01

    Serine/threonine protein phosphatase-5 (PP5) is a member of the PPP-gene family of protein phosphatases that is widely expressed in mammalian tissues and is highly conserved among eukaryotes. PP5 associates with several proteins that affect signal transduction networks, including the glucocorticoid receptor (GR)-heat shock protein-90 (Hsp90)-heterocomplex, the CDC16 and CDC27 subunits of the anaphase-promoting complex, elF2alpha kinase, the A subunit of PP2A, the G12-alpha / G13-alpha subunits of heterotrimeric G proteins and DNA-PK. The catalytic domain of PP5 (PP5c) shares 35-45% sequence identity with the catalytic domains of other PPP-phosphatases, including protein phosphatase-1 (PP1), -2A (PP2A), -2B / calcineurin (PP2B), -4 (PP4), -6 (PP6), and -7 (PP7). Like PP1, PP2A and PP4, PP5 is also sensitive to inhibition by okadaic acid, microcystin, cantharidin, tautomycin, and calyculin A. Here we report the crystal structure of the PP5 catalytic domain (PP5c) at a resolution of 1.6 angstroms. From this structure we propose a mechanism for PP5-mediated hydrolysis of phosphoprotein substrates, which requires the precise positioning of two metal ions within a conserved Asp(sup 271)-M(sub 1):M(sub 2)-W(sup 1)-His(sup 304)-Asp(sup 274) catalytic motif. The structure of PP5c provides a possible structural basis for explaining the exceptional catalytic proficiency of protein phosphatases, which are among the most powerful known catalysts. Resolution of the entire C-terminus revealed a novel subdomain, and the structure of the PP5c should also aid development of type-specific inhibitors.

  7. Phosphatases in plants.

    Schweighofer, Alois; Meskiene, Irute

    2015-01-01

    Reversible protein phosphorylation is an essential posttranslational modification mechanism executed by opposing actions of protein phosphatases and protein kinases. About 1,000 predicted kinases in Arabidopsis thaliana kinome predominate the number of protein phosphatases, of which there are only ~150 members in Arabidopsis. Protein phosphatases were often referred to as "housekeeping" enzymes, which act to keep eukaryotic systems in balance by counteracting the activity of protein kinases. However, recent investigations reveal the crucial and specific regulatory functions of phosphatases in cell signaling. Phosphatases operate in a coordinated manner with the protein kinases, to execute their important function in determining the cellular response to a physiological stimulus. Closer examination has established high specificity of phosphatases in substrate recognition and important roles in plant signaling pathways, such as pathogen defense and stress regulation, light and hormonal signaling, cell cycle and differentiation, metabolism, and plant growth. In this minireview we provide a compact overview about Arabidopsis protein phosphatase families, as well as members of phosphoglucan and lipid phosphatases, and highlight the recent discoveries in phosphatase research. PMID:25930691

  8. The myeloperoxidase-derived oxidant hypothiocyanous acid inhibits protein tyrosine phosphatases via oxidation of key cysteine residues

    Cook, Naomi L.; Moeke, Cassidy H.; Fantoni, Luca I.;

    2016-01-01

    Phosphorylation of protein tyrosine residues is critical to cellular processes, and is regulated by kinases and phosphatases (PTPs). PTPs contain a redox-sensitive active site Cys residue, which is readily oxidized. Myeloperoxidase, released from activated leukocytes, catalyzes thiocyanate ion (S...

  9. Interaction of NCOR/SMRT Repressor Complexes with Papillomavirus E8^E2C Proteins Inhibits Viral Replication.

    Dreer, Marcel; Fertey, Jasmin; van de Poel, Saskia; Straub, Elke; Madlung, Johannes; Macek, Boris; Iftner, Thomas; Stubenrauch, Frank

    2016-04-01

    Infections with high-risk human papillomaviruses (HR-HPV) such as HPV16 and 31 can lead to ano-genital and oropharyngeal cancers and HPV types from the beta genus have been implicated in the development of non-melanoma skin cancer. HPV replicate as nuclear extrachromosomal plasmids at low copy numbers in undifferentiated cells. HPV16 and 31 mutants have indicated that these viruses express an E8^E2C protein which negatively regulates genome replication. E8^E2C shares the DNA-binding and dimerization domain (E2C) with the essential viral replication activator E2 and the E8 domain replaces the replication/transcription activation domain of E2. The HR-HPV E8 domain is required for inhibiting viral transcription and the replication of the viral origin mediated by viral E1 and E2 proteins. We show now that E8^E2C also limits replication of HPV1, a mu-PV and HPV8, a beta-PV, in normal human keratinocytes. Proteomic analyses identified all NCoR/SMRT corepressor complex components (HDAC3, GPS2, NCoR, SMRT, TBL1 and TBLR1) as co-precipitating host cell proteins for HPV16 and 31 E8^E2C proteins. Co-immunoprecipitation and co-localization experiments revealed that NCoR/SMRT components interact with HPV1, 8, 16 and 31 E8^E2C proteins in an E8-dependent manner. SiRNA knock-down experiments confirm that NCoR/SMRT components are critical for both the inhibition of transcription and HPV origin replication by E8^E2C proteins. Furthermore, a dominant-negative NCoR fragment activates transcription and replication only from HPV16 and 31 wt but not from mutant genomes encoding NCoR/SMRT-binding deficient E8^E2C proteins. In summary, our data suggest that the repressive function of E8^E2C is highly conserved among HPV and that it is mediated by an E8-dependent interaction with NCoR/SMRT complexes. Our data also indicate for the first time that NCoR/SMRT complexes not only are involved in inhibiting cellular and viral transcription but also in controlling the replication of HPV origins

  10. Identification of protein tyrosine phosphatase 1B and casein as substrates for 124-v-Mos

    Stabel Silvia

    2002-04-01

    Full Text Available Abstract Background The mos proto-oncogene encodes a cytoplasmic serine/threonine-specific protein kinase with crucial function during meiotic cell division in vertebrates. Based on oncogenic amino acid substitutions the viral derivative, 124-v-Mos, displays constitutive protein kinase activity and functions independent of unknown upstream effectors of mos protein kinase. We have utilized this property of 124-v-Mos and screened for novel mos substrates in immunocomplex kinase assays in vitro. Results We generated recombinant 124-v-Mos using the baculovirus expression system in Spodoptera frugiperda cells and demonstrated constitutive kinase activity by the ability of 124-v-Mos to auto-phosphorylate and to phosphorylate vimentin, a known substrate of c-Mos. Using this approach we analyzed a panel of acidic and basic substrates in immunocomplex protein kinase assays and identified novel in vitro substrates for 124-v-Mos, the protein tyrosine phosphatase 1B (PTP1B, alpha-casein and beta-casein. We controlled mos-specific phosphorylation of PTP1B and casein in comparative assays using a synthetic kinase-inactive 124-v-Mos mutant and further, tryptic digests of mos-phosphorylated beta-casein identified a phosphopeptide specifically targeted by wild-type 124-v-Mos. Two-dimensional phosphoamino acid analyses showed that 124-v-mos targets serine and threonine residues for phosphorylation in casein at a 1:1 ratio but auto-phosphorylation occurs predominantly on serine residues. Conclusion The mos substrates identified in this study represent a basis to approach the identification of the mos-consensus phosphorylation motif, important for the development of specific inhibitors of the Mos protein kinase.

  11. Inhibition of Setaria cervi protein tyrosine phosphatases by Phenylarsine oxide: A proteomic and biochemical study.

    Singh, Neetu; Wadhawan, Mohit; Tiwari, Savitri; Kumar, Ranjeet; Rathaur, Sushma

    2016-07-01

    Phenylarsine oxide (PAO), a specific protein tyrosine phosphatase (PTP) inhibitor significantly decreased the motility and viability of Setaria cervi ultimately leading to its death. The PTP activity present in the cytosolic and detergent soluble fractions as well as on surface of these parasites was significantly inhibited by PAO. A marked alteration in protein spots abundance after proteomic analysis showed 14 down-regulated and 9 upregulated spots in the treated parasites as compared to the control. The PTP inhibition led to increase in the cytosolic and mitochondrial calpain activity in these parasites. PAO also blocked the ATP generation in the parasite depicted by reduced activity of phosphoglycerate kinase and expression of enolase. An increased ROS level, induced lipid peroxidation/protein carbonyl formation and decreased activity of different antioxidant enzymes like thioredoxin reductase, glutathione reductase and glutathione transferases was also observed in the PAO treated parasites. PAO, thus disturbs the overall homeostasis of the filarial parasite by inhibiting PTPs. Thereby suggesting that these molecules could be used as a good chemotherapeutic target for lymphatic filariasis. PMID:26965172

  12. BRCA1 affects protein phosphatase 6 signalling through its interaction with ANKRD28.

    Vincent, Anne; Berthel, Elise; Dacheux, Estelle; Magnard, Clémence; Venezia, Nicole L Dalla

    2016-04-01

    The tumour suppressor BRCA1 (breast and ovarian cancer-susceptibility gene 1) is implicated in several nuclear processes including DNA repair, transcription regulation and chromatin remodelling. BRCA1 also has some cytoplasmic functions including a pro-apoptotic activity. We identified ANKRD28 (ankyrin repeat domain 28) as a novel BRCA1-interacting protein in a yeast two-hybrid screen and confirmed this interaction by reciprocal immunoprecipitations of the two overexpressed proteins. Endogenous interaction between BRCA1 and ANKRD28 was also observed by co-immunoprecipitation and located in the cytoplasm by proximity ligation assay. The main site of interaction of ANKRD28 on BRCA1 is located in its intrinsically disordered scaffold central region. Whereas ANKRD28 silencing results in a destabilization of IκBε (inhibitor of nuclear factor κBε) through its activation of PP6 (protein phosphatase 6) co-regulator upon TNFα (tumour necrosis factor α) stimulation, BRCA1 overexpression stabilizes IκBε. A truncated form of BRCA1 that does not interact with ANKRD28 has no such effect. Our findings suggest that BRCA1 is a novel modulator of PP6 signalling via its interaction with ANKRD28. This new cytoplasmic process might participate in BRCA1 tumour-suppressor function. PMID:27026398

  13. Beyond the Dopamine Receptor: Regulation and Roles of Serine/Threonine Protein Phosphatases

    Sven I Walaas

    2011-08-01

    Full Text Available Dopamine plays an important modulatory role in the central nervous system, helping to control critical aspects of motor function and reward learning. Alteration in normal dopaminergic neurotransmission underlies multiple neurological diseases including schizophrenia, Huntington's disease and Parkinson's disease. Modulation of dopamine-regulated signaling pathways is also important in the addictive actions of most drugs of abuse. Our studies over the last 30 years have focused on the molecular actions of dopamine acting on medium spiny neurons, the predominant neurons of the neostriatum. Striatum-enriched phosphoproteins, particularly DARPP-32, RCS (Regulator of Calmodulin Signaling and ARPP-16, mediate pleiotropic actions of dopamine. Notably, each of these proteins, either directly or indirectly, regulates the activity of one of the three major subclasses of serine/threonine protein phosphatases, PP1, PP2B and PP2A, respectively. For example, phosphorylation of DARPP-32 at Thr34 by protein kinase A results in potent inhibition of PP1, leading to potentiation of dopaminergic signaling at multiple steps from the dopamine receptor to the nucleus. The discovery of DARPP-32 and its emergence as a critical molecular integrator of striatal signaling will be discussed, as will more recent studies that highlight novel roles for RCS and ARPP-16 in dopamine-regulated striatal signaling pathways.

  14. Unbiased identification of substrates of protein tyrosine phosphatase ptp-3 in C. elegans.

    Mitchell, Christopher J; Kim, Min-Sik; Zhong, Jun; Nirujogi, Raja Sekhar; Bose, Anjun K; Pandey, Akhilesh

    2016-06-01

    The leukocyte antigen related (LAR) family of receptor-like protein tyrosine phosphatases has three members in humans - PTPRF, PTPRD and PTPRS - that have been implicated in diverse processes including embryonic development, inhibition of cell growth and axonal guidance. Mutations in the LAR family are associated with developmental defects such as cleft palate as well as various cancers including breast, neck, lung, colon and brain. Although this family of tyrosine phosphatases is important for many developmental processes, little is known of their substrates. This is partially due to functional redundancy within the LAR family, as deletion of a single gene in the LAR family does not have an appreciable phenotype, but a dual knockout is embryonically lethal in mouse models. To circumvent the inability to knockout multiple members of the LAR family in mouse models, we used a knockout of ptp-3, which is the only known ortholog of the LAR family in Caenorhabditis elegans and allows for the study of the LAR family at the organismal level. Using SILAC-based quantitative phosphoproteomics, we identified 255 putative substrates of ptp-3, which included four of the nine known annotated substrates of the LAR family. A motif analysis of the identified phosphopeptides allowed for the determination of sequences that appear to be preferentially dephosphorylated. Finally, we discovered that kinases were overrepresented in the list of identified putative substrates and tyrosine residues whose phosphorylation is known to increase kinase activity were dephosphorylated by ptp-3. These data are suggestive of ptp-3 as a potential negative regulator of several kinase families, such as the mitogen activated kinases (MAPKs), and multiple tyrosine kinases including FER, MET, and NTRK2. PMID:27067626

  15. Protein-tyrosine phosphatase activity of Coxiella burnetii that inhibits human neutrophils

    Supernatants prepared from disrupted Coxiella burnetii posses acid phosphatase (ACP) activity that apparently accounts for the inhibition of the metabolic burst of formyl-Met-Leu-Phe(fMLP)-stimulated human neutrophils. Results are presented regarding purification and biochemical-biological characterization of the ACP. The highly purified enzyme, which exhibited an apparent M of 91 K and optimal activity at pH 5.0, also inhibited neutrophils. The enzyme retained full activity at pH 4.5, 5.5, and 7.4, when incubated overnight at 0 grad C and room temperature; at pH 5.5, it retained full activity after overnight incubation at 37 grad C. Apparently, the enzyme contains asparagine-linked but not serine- or threonine-liked glycan residues since its treatment with N-glycosidase F decreased its Mr to 87 K and no changes were detected with O-glycosidase. The enzyme's capacity to hydrolyze phosphate from a number of phosphate-containing compounds was examined; five phospho-compounds were significantly hydrolyzed: 5'-CMP > fructose 1,6-diphosphate > tyrosine phosphate > 3'-AMP >5'-AMP. The ACP also dephosphorylated 32P-Raytide, a phosphotyrosine-containing peptide. Dephosphorylation of Raytide was inhibited by the following phosphatase inhibitors: sodium molybdate, potassium fluoride, sodium ortho-vanadate and D2, a heteropolymolybdate compound. These results indicate that C.burnetii ACP may play a role in disrupting tyrosine phosphorylation/dephosphorylation reactions associated with the signal transduction pathway culminating in the metabolic burst. Interestingly, Western blot analysis of ACP-inhibited neutrophils showed a marked increase in tyrosine phosphorylation of a 44 K protein as compared to uninhibited cells. (author)

  16. Actin-associated protein palladin is required for migration behavior and differentiation potential of C2C12 myoblast cells

    Highlights: • Palladin is involved in myogenesis in vitro. • Palladin knockdown by siRNA increases myoblast proliferation, viability and differentiation. • Palladin knockdown decreases C2C12 myoblast migration ability. - Abstract: The actin-associated protein palladin has been shown to be involved in differentiation processes in non-muscle tissues. However, but its function in skeletal muscle has rarely been studied. Palladin plays important roles in the regulation of diverse actin-related signaling in a number of cell types. Since intact actin-cytoskeletal remodeling is necessary for myogenesis, in the present study, we pursue to investigate the role of actin-associated palladin in skeletal muscle differentiation. Palladin in C2C12 myoblasts is knocked-down using specific small interfering RNA (siRNA). The results show that down-regulation of palladin decreased migratory activity of mouse skeletal muscle C2C12 myoblasts. Furthermore, the depletion of palladin enhances C2C12 vitality and proliferation. Of note, the loss of palladin promotes C2C12 to express the myosin heavy chain, suggesting that palladin has a role in the modulation of C2C12 differentiation. It is thus proposed that palladin is required for normal C2C12 myogenesis in vitro

  17. Actin-associated protein palladin is required for migration behavior and differentiation potential of C2C12 myoblast cells

    Nguyen, Ngoc Uyen Nhi; Liang, Vincent Roderick; Wang, Hao-Ven, E-mail: hvwang@mail.ncku.edu.tw

    2014-09-26

    Highlights: • Palladin is involved in myogenesis in vitro. • Palladin knockdown by siRNA increases myoblast proliferation, viability and differentiation. • Palladin knockdown decreases C2C12 myoblast migration ability. - Abstract: The actin-associated protein palladin has been shown to be involved in differentiation processes in non-muscle tissues. However, but its function in skeletal muscle has rarely been studied. Palladin plays important roles in the regulation of diverse actin-related signaling in a number of cell types. Since intact actin-cytoskeletal remodeling is necessary for myogenesis, in the present study, we pursue to investigate the role of actin-associated palladin in skeletal muscle differentiation. Palladin in C2C12 myoblasts is knocked-down using specific small interfering RNA (siRNA). The results show that down-regulation of palladin decreased migratory activity of mouse skeletal muscle C2C12 myoblasts. Furthermore, the depletion of palladin enhances C2C12 vitality and proliferation. Of note, the loss of palladin promotes C2C12 to express the myosin heavy chain, suggesting that palladin has a role in the modulation of C2C12 differentiation. It is thus proposed that palladin is required for normal C2C12 myogenesis in vitro.

  18. Elongation factor-1A1 is a novel substrate of the protein phosphatase 1-TIMAP complex.

    Boratkó, Anita; Péter, Margit; Thalwieser, Zsófia; Kovács, Előd; Csortos, Csilla

    2015-12-01

    TIMAP (TGF-β inhibited membrane associated protein) is a protein phosphatase 1 (PP1) regulatory subunit highly abundant in endothelial cells and it is involved in the maintenance of pulmonary endothelial barrier function. It localizes mainly in the plasma membrane, but it is also present in the nuclei and cytoplasm. Direct interaction of TIMAP with the eukaryotic elongation factor 1 A1 (eEF1A1) is shown by pull-down, LC-MS/MS, Far-Western and immunoprecipitations. In connection with the so called moonlighting functions of the elongation factor, eEF1A is thought to establish protein-protein interactions through a transcription-dependent nuclear export motif, TD-NEM, and to aid nuclear export of TD-NEM containing proteins. We found that a TD-NEM-like motif of TIMAP has a critical role in its specific binding to eEF1A1. However, eEF1A1 is not or not exclusively responsible for the nuclear export of TIMAP. On the contrary, TIMAP seems to regulate membrane localization of eEF1A1 as the elongation factor co-localized with TIMAP in the plasma membrane fraction of control endothelial cells, but it has disappeared from the membrane in TIMAP depleted cells. It is demonstrated that membrane localization of eEF1A1 depends on the phosphorylation state of its Thr residue(s); and ROCK phosphorylated eEF1A1 is a novel substrate for TIMAP-PP1 underlining the complex regulatory role of TIMAP in the endothelium. The elongation factor seems to be involved in the regulation of endothelial cell attachment and spreading as silencing of eEF1A1 positively affected these processes which were monitored by transendothelial resistance measurements. PMID:26497934

  19. Alkaline phosphatase and OmpA protein can be translocated posttranslationally into membrane vesicles of Escherichia coli.

    Chen, L.; Rhoads, D; Tai, P C

    1985-01-01

    We previously described a system for translocating the periplasmic enzyme alkaline phosphatase and the outer membrane protein OmpA into inverted membrane vesicles of Escherichia coli. We have now optimized and substantially improved the translocation system by including polyamines and by reducing the amount of membrane used. Under these conditions, efficient translocation was seen even posttranslationally, i.e., when vesicles were not added until after protein synthesis was stopped. This was ...

  20. A low molecular weight protein tyrosine phosphatase from Synechocystis sp. strain PCC 6803: enzymatic characterization and identification of its potential substrates

    Mukhopadhyay, Archana; Kennelly, Peter J.

    2011-01-01

    The predicted protein product of open reading frame slr0328 from Synechocystis sp. PCC 6803, SynPTP, possesses significant amino acid sequence similarity with known low molecular weight protein tyrosine phosphatases (PTPs). To determine the functional properties of this hypothetical protein, open reading frame slr0328 was expressed in Escherichia coli. The purified recombinant protein, SynPTP, displayed its catalytic phosphatase activity towards several tyrosine, but not serine, phosphorylate...

  1. B′-protein phosphatase 2A is a functional binding partner of delta-retroviral integrase

    Maertens, Goedele N.

    2016-01-01

    To establish infection, a retrovirus must insert a DNA copy of its RNA genome into host chromatin. This reaction is catalysed by the virally encoded enzyme integrase (IN) and is facilitated by viral genus-specific host factors. Herein, cellular serine/threonine protein phosphatase 2A (PP2A) is identified as a functional IN binding partner exclusive to δ-retroviruses, including human T cell lymphotropic virus type 1 and 2 (HTLV-1 and HTLV-2) and bovine leukaemia virus (BLV). PP2A is a heterotrimer composed of a scaffold, catalytic and one of any of four families of regulatory subunits, and the interaction is specific to the B′ family of the regulatory subunits. B′-PP2A and HTLV-1 IN display nuclear co-localization, and the B′ subunit stimulates concerted strand transfer activity of δ-retroviral INs in vitro. The protein–protein interaction interface maps to a patch of highly conserved residues on B′, which when mutated render B′ incapable of binding to and stimulating HTLV-1 and -2 IN strand transfer activity. PMID:26657642

  2. Regulation of Ikaros function by casein kinase 2 and protein phosphatase 1

    Amy; K; Erbe; Aleksandar; Savic; Sinisa; Dovat

    2011-01-01

    The Ikaros gene encodes a zinc finger,DNA-binding protein that regulates gene transcription and chromatin remodeling.Ikaros is a master regulator of hematopoiesis and an established tumor suppressor.Moderate alteration of Ikaros activity (e.g.haploinsufficiency) appears to be sufficient to promote malignant transformation in human hematopoietic cells.This raises questions about the mechanisms that normally regulate Ikaros function and the potential of these mechanisms to contribute to the development of leukemia.The focus of this review is the regulation of Ikaros function by phosphorylation/dephosphorylation.Site-specific phosphorylation of Ikaros by casein kinase 2 (CK2) controls Ikaros DNA-binding ability and subcellular localization.As a consequence,the ability of Ikaros to regulate cell cycle progression,chromatin remodeling,target gene expression,and thymocyte differentiation are controlled by CK2.In addition,hyperphosphorylation of Ikaros by CK2 leads to decreased Ikaros levels due to ubiquitinmediated degradation.Dephosphorylation of Ikaros by protein phosphatase 1 (PP1) acts in opposition to CK2 to increase Ikaros stability and restore Ikaros DNA binding ability and pericentromeric localization.Thus,the CK2 and PP1 pathways act in concert to regulate Ikaros activity in hematopoiesis and as a tumor suppressor.This highlights the importance of these signal transduction pathways as potential mediators of leukemogenesis via their role in regulating the activities of Ikaros.

  3. Inactivation of Protein Tyrosine Phosphatases Enhances Interferon Signaling in Pancreatic Islets.

    Stanley, William J; Litwak, Sara A; Quah, Hong Sheng; Tan, Sih Min; Kay, Thomas W H; Tiganis, Tony; de Haan, Judy B; Thomas, Helen E; Gurzov, Esteban N

    2015-07-01

    Type 1 diabetes (T1D) is the result of an autoimmune assault against the insulin-producing pancreatic β-cells, where chronic local inflammation (insulitis) leads to β-cell destruction. T cells and macrophages infiltrate into islets early in T1D pathogenesis. These immune cells secrete cytokines that lead to the production of reactive oxygen species (ROS) and T-cell invasion and activation. Cytokine-signaling pathways are very tightly regulated by protein tyrosine phosphatases (PTPs) to prevent excessive activation. Here, we demonstrate that pancreata from NOD mice with islet infiltration have enhanced oxidation/inactivation of PTPs and STAT1 signaling compared with NOD mice that do not have insulitis. Inactivation of PTPs with sodium orthovanadate in human and rodent islets and β-cells leads to increased activation of interferon signaling and chemokine production mediated by STAT1 phosphorylation. Furthermore, this exacerbated STAT1 activation-induced cell death in islets was prevented by overexpression of the suppressor of cytokine signaling-1 or inactivation of the BH3-only protein Bim. Together our data provide a mechanism by which PTP inactivation induces signaling in pancreatic islets that results in increased expression of inflammatory genes and exacerbated insulitis. PMID:25732191

  4. Protein Tyrosine Phosphatase-1B Negatively Impacts Host Defense against Pseudomonas aeruginosa Infection.

    Yue, Lei; Xie, Zhongping; Li, Hua; Pang, Zheng; Junkins, Robert D; Tremblay, Michel L; Chen, Xiaochun; Lin, Tong-Jun

    2016-05-01

    Pseudomonas aeruginosa is a major opportunistic pathogen in immune-compromised individuals. Mechanisms governing immune responses to P. aeruginosa infection remain incompletely defined. Herein, we demonstrate that protein tyrosine phosphatase-1B (PTP1B) is a critical negative regulator in P. aeruginosa infection. PTP1B-deficient mice display greatly enhanced bacterial clearance and reduced disease scores, which are accompanied by increased neutrophil infiltration and cytokine production. Interestingly, PTP1B deficiency mainly up-regulates the production of interferon-stimulated response elements-regulated cytokines and chemokines, including chemokine ligand 5 (regulated on activation normal T cell expressed and secreted), CXCL10 (interferon γ-inducible protein 10), and interferon-β production. Further studies reveal that PTP1B deficiency leads to increased interferon regulatory factor 7 (IRF7) expression and activation. These findings demonstrate a novel regulatory mechanism of the immune response to P. aeruginosa infection through PTP1B-IRF7 interaction. This novel PTP1B-IRF7-interferon-stimulated response elements pathway may have broader implications in Toll-like receptor-mediated innate immunity. PMID:27105736

  5. IA-2, a transmembrane protein of the protein tyrosine phosphatase family, is a major autoantigen in insulin-dependent diabetes mellitus.

    Lan, M S; Wasserfall, C; Maclaren, N K; Notkins, A L

    1996-01-01

    IA-2 is a 105,847 Da transmembrane protein that belongs to the protein tyrosine phosphatase family. Immunoperoxidase staining with antibody raised against IA-2 showed that this protein is expressed in human pancreatic islet cells. In this study, we expressed the full-length cDNA clone of IA-2 in a rabbit reticulocyte transcription/translation system and used the recombinant radiolabeled IA-2 protein to detect autoantibodies by immunoprecipitation. Coded sera (100) were tested: 50 from patient...

  6. Protein phosphatases and chromatin modifying complexes in the inflammatory cascade in acute pancreatitis

    Javier Escobar

    2010-06-01

    Full Text Available Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of pro-inflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatin modifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE and the transcription factor CRE-binding protein (CREB. CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1 and histone deacetylases (HDACs. Class II HDACs are key transcriptional regulators whose activities are controlled via phosphorylation-dependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class II HDACs, triggering nuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.

  7. Protein phosphatases and chromatin modifying complexes in the inflammatory cascade in acute pancreatitis

    Javier; Escobar; Javier; Pereda; Alessandro; Arduini; Juan; Sastre; Juan; Sandoval; Luis; Aparisi; Gerardo; López-Rodas; Luis; Sabater

    2010-01-01

    Acute pancreatitis is an inflammation of the pancreas that may lead to systemic inflammatory response syndrome and death due to multiple organ failure. Acinar cells, together with leukocytes, trigger the inflammatory cascade in response to local damage of the pancreas. Amplification of the inflammatory cascade requires up-regulation of proinflammatory cytokines and this process is mediated not only by nuclear factor κB but also by chromatinmodifying complexes and chromatin remodeling. Among the different families of histone acetyltransferases, the p300/CBP family seems to be particularly associated with the inflammatory process. cAMP activates gene expression via the cAMP-responsive element (CRE) and the transcription factor CRE-binding protein (CREB). CREB can be phosphorylated and activated by different kinases, such as protein kinase A and MAPK, and then it recruits the histone acetyltransferase co-activator CREB-binding protein (CBP) and its homologue p300. The recruitment of CBP/p300 and changes in the level of histone acetylation are required for transcription activation. Transcriptional repression is also a dynamic and essential mechanism of down-regulation of genes for resolution of inflammation, which seems to be mediated mainly by protein phosphatases (PP1, PP2A and MKP1) and histone deacetylases(HDACs) .Class HDACs are key transcriptional regulators whose activities are controlled via phosphorylationdependent nucleo/cytoplasmic shuttling. PP2A is responsible for dephosphorylation of class HDACs, triggeringnuclear localization and repression of target genes, whereas phosphorylation triggers cytoplasmic localization leading to activation of target genes. The potential benefit from treatment with phosphodiesterase inhibitors and histone deacetylase inhibitors is discussed.

  8. Phosphorylation of SET protein at Ser171 by protein kinase D2 diminishes its inhibitory effect on protein phosphatase 2A.

    Atsushi Irie

    Full Text Available We previously reported that protein kinase D2 (PKD2 in T cells is promptly activated after T-cell receptor (TCR stimulation and involved in the activation of interleukin-2 promoter and T cell death, and that one of its candidate substrate is SET protein, a natural inhibitor for protein phosphatase 2A (PP2A. In this study, we investigated the target amino acid residues of SET phosphorylated by PKD2 and the effects of phosphorylation of SET on PP2A phosphatase activity. In vitro kinase assay using various recombinant SET mutants having Ser/Thr to Ala substitutions revealed that Ser171 of SET is one of the sites phosphorylated by PKD2. Recombinant SET with phosphorylation-mimic Ser171 to Glu substitution reduced its inhibitory effects on PP2A phosphatase activity compared with Ser171 to Ala substituted or wild-type SET. In addition, knockdown of PKD2 in Jurkat cells by RNAi or treatment of human CD4(+ T cell clone with the PKD2 inhibitor Gö6976 resulted in reduced PP2A activity after TCR-stimulation judged from phosphorylation status of Tyr307 of the catalytic subunit of PP2A. These results suggest that PKD2 is involved in the regulation of PP2A activity in activated T cells through phosphorylation of Ser171 of SET.

  9. Expression of a truncated receptor protein tyrosine phosphatase kappa in the brain of an adult transgenic mouse

    Shen, P; Canoll, P D; Sap, J;

    1999-01-01

    Receptor protein tyrosine phosphatases (RPTPs) comprise a family of proteins that feature intracellular phosphatase domains and an ectodomain with putative ligand-binding motifs. Several RPTPs are expressed in the brain, including RPTP-kappa which participates in homophilic cell-cell interactions...... developmental processes such as axonal growth and target recognition, as has been demonstrated for certain Drosophila RPTPs. The brain distribution of RPTP-kappa-expressing cells has not been determined, however. In a gene-trap mouse model with a beta-gal+neo (beta-geo) insertion in the endogenous RPTP......-kappa gene, the consequent loss of RPTP-kappa's enzymatic activity does not produce any obvious phenotypic defects [W.C. Skarnes, J.E. Moss, S.M. Hurtley, R.S.P. Beddington, Capturing genes encoding membrane and secreted proteins important for mouse development, Proc. Natl. Acad. Sci. U.S.A. 92 (1995) 6592...

  10. Pancreatic Protein Tyrosine Phosphatase 1B Deficiency Exacerbates Acute Pancreatitis in Mice.

    Bettaieb, Ahmed; Koike, Shinichiro; Chahed, Samah; Bachaalany, Santana; Griffey, Stephen; Sastre, Juan; Haj, Fawaz G

    2016-08-01

    Acute pancreatitis (AP) is a common and devastating gastrointestinal disorder that causes significant morbidity. The disease starts as local inflammation in the pancreas that may progress to systemic inflammation and complications. Protein tyrosine phosphatase 1B (PTP1B) is implicated in inflammatory signaling, but its significance in AP remains unclear. To investigate whether PTP1B may have a role in AP, we used pancreas PTP1B knockout (panc-PTP1B KO) mice and determined the effects of pancreatic PTP1B deficiency on cerulein- and arginine-induced acute pancreatitis. We report that PTP1B protein expression was increased in the early phase of AP in mice and rats. In addition, histological analyses of pancreas samples revealed enhanced features of AP in cerulein-treated panc-PTP1B KO mice compared with controls. Moreover, cerulein- and arginine-induced serum amylase and lipase were significantly higher in panc-PTP1B KO mice compared with controls. Similarly, pancreatic mRNA and serum concentrations of the inflammatory cytokines IL-1B, IL-6, and tumor necrosis factor-α were increased in panc-PTP1B KO mice compared with controls. Furthermore, panc-PTP1B KO mice exhibited enhanced cerulein- and arginine-induced NF-κB inflammatory response accompanied with increased mitogen-activated protein kinases activation and elevated endoplasmic reticulum stress. Notably, these effects were recapitulated in acinar cells treated with a pharmacological inhibitor of PTP1B. These findings reveal a novel role for pancreatic PTP1B in cerulein- and arginine-induced acute pancreatitis. PMID:27461362

  11. Screening of a Library of FDA-Approved Drugs Identifies Several Enterovirus Replication Inhibitors That Target Viral Protein 2C.

    Ulferts, Rachel; de Boer, S Matthijn; van der Linden, Lonneke; Bauer, Lisa; Lyoo, Hey Rhyoung; Maté, Maria J; Lichière, Julie; Canard, Bruno; Lelieveld, Daphne; Omta, Wienand; Egan, David; Coutard, Bruno; van Kuppeveld, Frank J M

    2016-05-01

    Enteroviruses (EVs) represent many important pathogens of humans. Unfortunately, no antiviral compounds currently exist to treat infections with these viruses. We screened the Prestwick Chemical Library, a library of approved drugs, for inhibitors of coxsackievirus B3, identified pirlindole as a potent novel inhibitor, and confirmed the inhibitory action of dibucaine, zuclopenthixol, fluoxetine, and formoterol. Upon testing of viruses of several EV species, we found that dibucaine and pirlindole inhibited EV-B and EV-D and that dibucaine also inhibited EV-A, but none of them inhibited EV-C or rhinoviruses (RVs). In contrast, formoterol inhibited all enteroviruses and rhinoviruses tested. All compounds acted through the inhibition of genome replication. Mutations in the coding sequence of the coxsackievirus B3 (CV-B3) 2C protein conferred resistance to dibucaine, pirlindole, and zuclopenthixol but not formoterol, suggesting that 2C is the target for this set of compounds. Importantly, dibucaine bound to CV-B3 protein 2C in vitro, whereas binding to a 2C protein carrying the resistance mutations was reduced, providing an explanation for how resistance is acquired. PMID:26856848

  12. Molecular dynamics simulations of interaction between protein-tyrosine phosphatase 1B and a bidentate inhibitor

    Gui-xia LIU; Jin-zhi TAN; Chun-ying NIU; Jian-hua SHEN; Xiao-min LUO; Xu SHEN; Kai-xian CHEN; Hua-liang JIANG

    2006-01-01

    Aim: To investigate the dynamic properties of protein-tyrosine phosphatase (PTP)1B and reveal the structural factors responsible for the high inhibitory potency and selectivity of the inhibitor SNA for PTP1B. Methods: We performed molecular dynamics (MD) simulations using a long time-scale for both PTP1B and PTP1B complexed with the inhibitor SNA, the most potent and selective PTP1B inhibitor reported to date. The trajectories were analyzed by using principal component analysis. Results: Trajectory analyses showed that upon binding the ligand, the flexibility of the entire PTP1B molecule decreases. The most notable change is the movement of the WPD-loop. Our simulation results also indicated that electrostatic interactions contribute more to PTP1B-SNA complex conformation than the van der Waals interactions, and that Lys41, Arg47, and Asp48 play important roles in determining the conformation of the inhibitor SNA and in the potency and selectivity of the inhibitor. Of these, Arg47 contributed most. These results were in agreement with previous experimental results. Conclusion: The information presented here suggests that potent and selective PTP1B inhibitors can be designed by targeting the surface residues, for example the region containing Lys41,Arg47, and Asp48, instead of the second phosphate binding site (besides the active phosphate binding site).

  13. Oleanane triterpenes as protein tyrosine phosphatase 1B (PTP1B) inhibitors from Camellia japonica.

    Uddin, Mohammad Nasir; Sharma, Govinda; Yang, Jun-Li; Choi, Hong Seok; Lim, Seong-Il; Kang, Keon Wook; Oh, Won Keun

    2014-07-01

    Protein tyrosine phosphatase 1B (PTP1B) plays a key role in metabolic signaling, thereby making it an exciting drug target for type 2 diabetes and obesity. Besides, there is substantial evidence that shows its overexpression is involved in breast cancer, which suggests that selective PTP1B inhibition might be effective in breast cancer treatment. As part of our continuous research on PTP1B inhibitors from medicinal plants, four oleanane-type triterpenes were isolated from an EtOAc-soluble extract of fruit peels of Camellia japonica (Theaceae), together with 6 previously known compounds of this class. Their structures were determined on the basis of spectroscopic data analysis (UV, IR, (1)H and (13)CNMR, HMBC, HSQC, NOESY, and MS). All isolates were evaluated for their inhibitory effects on PTP1B, as well as their cytotoxic effects against human breast cancer cell lines MCF7, MCF7/ADR, and MDA-MB-231. Several compounds with OH-3 or/and COOH-28 functionalities showed strong PTP1B inhibitory activity (IC50 values ranging from 3.77±0.11 to 6.40±0.81 μM) as well as significant cytotoxicity (IC50 values ranging from 0.51±0.05 to 13.55±1.44 μM). PMID:24815008

  14. A Novel Molecular Diagnostic of Glioblastomas: Detection of an Extracellular Fragment of Protein Tyrosine Phosphatase μ

    Susan M. Burden-Gulley

    2010-04-01

    Full Text Available We recently found that normal human brain and low-grade astrocytomas express the receptor protein tyrosine phosphatase mu (PTPμ and that the more invasive astrocytomas, glioblastoma multiforme (GBM, downregulate full-length PTPμ expression. Loss of PTPμ expression in GBMs is due to proteolytic cleavage that generates an intracellular and potentially a cleaved and released extracellular fragment of PTPμ. Here, we identify that a cleaved extracellular fragment containing the domains required for PTPμ-mediated adhesion remains associated with GBM tumor tissue. We hypothesized that detection of this fragment would make an excellent diagnostic tool for the localization of tumor tissue within the brain. To this end, we generated a series of fluorescently tagged peptide probes that bind the PTPμ fragment. The peptide probes specifically recognize GBM cells in tissue sections of surgically resected human tumors. To test whether the peptide probes are able to detect GBM tumors in vivo, the PTPμ peptide probes were tested in both mouse flank and intracranial xenograft human glioblastoma tumor model systems. The glial tumors were molecularly labeled with the PTPμ peptide probes within minutes of tail vein injection using the Maestro FLEX In Vivo Imaging System. The label was stable for at least 3 hours. Together, these results indicate that peptide recognition of the PTPμ extracellular fragment provides a novel molecular diagnostic tool for detection of human glioblastomas. Such a tool has clear translational applications and may lead to improved surgical resections and prognosis for patients with this devastating disease.

  15. The Ablation of Mitochondrial Protein Phosphatase Pgam5 Confers Resistance Against Metabolic Stress

    Shiori Sekine

    2016-03-01

    Full Text Available Phosphoglycerate mutase family member 5 (PGAM5 is a mitochondrial protein phosphatase that has been reported to be involved in various stress responses from mitochondrial quality control to cell death. However, its roles in vivo are largely unknown. Here, we show that Pgam5-deficient mice are resistant to several metabolic insults. Under cold stress combined with fasting, Pgam5-deficient mice better maintained body temperature than wild-type mice and showed an extended survival rate. Serum triglycerides and lipid content in brown adipose tissue (BAT, a center of adaptive thermogenesis, were severely reduced in Pgam5-deficient mice. Moreover, although Pgam5 deficiency failed to maintain proper mitochondrial integrity in BAT, it reciprocally resulted in the dramatic induction of fibroblast growth factor 21 (FGF21 that activates various functions of BAT including thermogenesis. Thus, the enhancement of lipid metabolism and FGF21 may contribute to the cold resistance of Pgam5-deficient mice under fasting condition. Finally, we also found that Pgam5-deficient mice are resistant to high-fat-diet-induced obesity. Our study uncovered that PGAM5 is involved in the whole-body metabolism in response to stresses that impose metabolic challenges on mitochondria.

  16. The Ablation of Mitochondrial Protein Phosphatase Pgam5 Confers Resistance Against Metabolic Stress.

    Sekine, Shiori; Yao, Akari; Hattori, Kazuki; Sugawara, Sho; Naguro, Isao; Koike, Masato; Uchiyama, Yasuo; Takeda, Kohsuke; Ichijo, Hidenori

    2016-03-01

    Phosphoglycerate mutase family member 5 (PGAM5) is a mitochondrial protein phosphatase that has been reported to be involved in various stress responses from mitochondrial quality control to cell death. However, its roles in vivo are largely unknown. Here, we show that Pgam5-deficient mice are resistant to several metabolic insults. Under cold stress combined with fasting, Pgam5-deficient mice better maintained body temperature than wild-type mice and showed an extended survival rate. Serum triglycerides and lipid content in brown adipose tissue (BAT), a center of adaptive thermogenesis, were severely reduced in Pgam5-deficient mice. Moreover, although Pgam5 deficiency failed to maintain proper mitochondrial integrity in BAT, it reciprocally resulted in the dramatic induction of fibroblast growth factor 21 (FGF21) that activates various functions of BAT including thermogenesis. Thus, the enhancement of lipid metabolism and FGF21 may contribute to the cold resistance of Pgam5-deficient mice under fasting condition. Finally, we also found that Pgam5-deficient mice are resistant to high-fat-diet-induced obesity. Our study uncovered that PGAM5 is involved in the whole-body metabolism in response to stresses that impose metabolic challenges on mitochondria. PMID:27077115

  17. Protein tyrosine phosphatase non-receptor type 2 and inflammatory bowel disease.

    Spalinger, Marianne R; McCole, Declan F; Rogler, Gerhard; Scharl, Michael

    2016-01-21

    Genome wide association studies have associated single nucleotide polymorphisms within the gene locus encoding protein tyrosine phosphatase non-receptor type 2 (PTPN2) with the onset of inflammatory bowel disease (IBD) and other inflammatory disorders. Expression of PTPN2 is enhanced in actively inflamed intestinal tissue featuring a marked up-regulation in intestinal epithelial cells. PTPN2 deficient mice suffer from severe intestinal and systemic inflammation and display aberrant innate and adaptive immune responses. In particular, PTPN2 is involved in the regulation of inflammatory signalling cascades, and critical for protecting intestinal epithelial barrier function, regulating innate and adaptive immune responses, and finally for maintaining intestinal homeostasis. On one hand, dysfunction of PTPN2 has drastic effects on innate host defence mechanisms, including increased secretion of pro-inflammatory cytokines, limited autophagosome formation in response to invading pathogens, and disruption of the intestinal epithelial barrier. On the other hand, PTPN2 function is crucial for controlling adaptive immune functions, by regulating T cell proliferation and differentiation as well as maintaining T cell tolerance. In this way, dysfunction of PTPN2 contributes to the manifestation of IBD. The aim of this review is to present an overview of recent findings on the role of PTPN2 in intestinal homeostasis and the impact of dysfunctional PTPN2 on intestinal inflammation. PMID:26811645

  18. Role of Receptor Protein Tyrosine Phosphatase γ in Sensing Extracellular CO2 and HCO3.

    Zhou, Yuehan; Skelton, Lara A; Xu, Lumei; Chandler, Margaret P; Berthiaume, Jessica M; Boron, Walter F

    2016-09-01

    Regulation of blood pH-critical for virtually every facet of life-requires that the renal proximal tubule (PT) adjust its rate of H(+) secretion (nearly the same as the rate of HCO3 (-) reabsorption, JHCO3 ) in response to changes in blood [CO2] and [HCO3 (-)]. Yet CO2/HCO3 (-) sensing mechanisms remain poorly characterized. Because receptor tyrosine kinase inhibitors render JHCO3 in the PT insensitive to changes in CO2 concentration, we hypothesized that the structural features of receptor protein tyrosine phosphatase-γ (RPTPγ) that are consistent with binding of extracellular CO2 or HCO3 (-) facilitate monitoring of blood CO2/HCO3 (-) concentrations. We now report that PTs express RPTPγ on blood-facing membranes. Moreover, RPTPγ deletion in mice eliminated the CO2 and HCO3 (-) sensitivities of JHCO3 as well as the normal defense of blood pH during whole-body acidosis. Thus, RPTPγ appears to be a novel extracellular CO2/HCO3 (-) sensor critical for pH homeostasis. PMID:26839367

  19. NLRP3 tyrosine phosphorylation is controlled by protein tyrosine phosphatase PTPN22.

    Spalinger, Marianne R; Kasper, Stephanie; Gottier, Claudia; Lang, Silvia; Atrott, Kirstin; Vavricka, Stephan R; Scharl, Sylvie; Gutte, Petrus M; Grütter, Markus G; Beer, Hans-Dietmar; Contassot, Emmanuel; Chan, Andrew C; Dai, Xuezhi; Rawlings, David J; Mair, Florian; Becher, Burkhard; Falk, Werner; Fried, Michael; Rogler, Gerhard; Scharl, Michael

    2016-05-01

    Inflammasomes form as the result of the intracellular presence of danger-associated molecular patterns and mediate the release of active IL-1β, which influences a variety of inflammatory responses. Excessive inflammasome activation results in severe inflammatory conditions, but physiological IL-1β secretion is necessary for intestinal homeostasis. Here, we have described a mechanism of NLRP3 inflammasome regulation by tyrosine phosphorylation of NLRP3 at Tyr861. We demonstrated that protein tyrosine phosphatase non-receptor 22 (PTPN22), variants in which are associated with chronic inflammatory disorders, dephosphorylates NLRP3 upon inflammasome induction, allowing efficient NLRP3 activation and subsequent IL-1β release. In murine models, PTPN22 deficiency resulted in pronounced colitis, increased NLRP3 phosphorylation, but reduced levels of mature IL-1β. Conversely, patients with inflammatory bowel disease (IBD) that carried an autoimmunity-associated PTPN22 variant had increased IL-1β levels. Together, our results identify tyrosine phosphorylation as an important regulatory mechanism for NLRP3 that prevents aberrant inflammasome activation. PMID:27043286

  20. The effect of eicosapentaenoic and docosahexaenoic acid on protein synthesis and breakdown in murine C2C12 myotubes

    Kamolrat, Torkamol [Musculoskeletal Research Programme, Institute of Medical Sciences, University of Aberdeen, AB25 2ZD (United Kingdom); Gray, Stuart R., E-mail: s.r.gray@abdn.ac.uk [Musculoskeletal Research Programme, Institute of Medical Sciences, University of Aberdeen, AB25 2ZD (United Kingdom)

    2013-03-22

    Highlights: ► EPA can enhance protein synthesis and retard protein breakdown in muscle cells. ► These effects were concurrent with increases in p70s6k and FOXO3a phosphorylation. ► EPA may be a useful tool in the treatment of muscle wasting conditions. -- Abstract: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been found to stimulate protein synthesis with little information regarding their effects on protein breakdown. Furthermore whether there are distinct effects of EPA and DHA remains to be established. The aim of the current study was to determine the distinct effects of EPA and DHA on protein synthesis, protein breakdown and signalling pathways in C2C12 myotubes. Fully differentiated C2C12 cells were incubated for 24 h with 0.1% ethanol (control), 50 μM EPA or 50 μM DHA prior to experimentation. After serum (4 h) and amino acid (1 h) starvation cells were stimulated with 2 mM L-leucine and protein synthesis measured using {sup 3}H-labelled phenylalanine. Protein breakdown was measured using {sup 3}H-labelled phenylalanine and signalling pathways (Akt, mTOR, p70S6k, 4EBP1, rps6 and FOXO3a) via Western blots. Data revealed that after incubation with EPA protein synthesis was 25% greater (P < 0.05) compared to control cells, with no effect of DHA. Protein breakdown was 22% (P < 0.05) lower, compared to control cells, after incubation with EPA, with no effect of DHA. Analysis of signalling pathways revealed that both EPA and DHA incubation increased (P < 0.05) p70s6k phosphorylation, EPA increased (P < 0.05) FOXO3a phosphorylation, with no alteration in other signalling proteins. The current study has demonstrated distinct effects of EPA and DHA on protein metabolism with EPA showing a greater ability to result in skeletal muscle protein accretion.

  1. The effect of eicosapentaenoic and docosahexaenoic acid on protein synthesis and breakdown in murine C2C12 myotubes

    Highlights: ► EPA can enhance protein synthesis and retard protein breakdown in muscle cells. ► These effects were concurrent with increases in p70s6k and FOXO3a phosphorylation. ► EPA may be a useful tool in the treatment of muscle wasting conditions. -- Abstract: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have been found to stimulate protein synthesis with little information regarding their effects on protein breakdown. Furthermore whether there are distinct effects of EPA and DHA remains to be established. The aim of the current study was to determine the distinct effects of EPA and DHA on protein synthesis, protein breakdown and signalling pathways in C2C12 myotubes. Fully differentiated C2C12 cells were incubated for 24 h with 0.1% ethanol (control), 50 μM EPA or 50 μM DHA prior to experimentation. After serum (4 h) and amino acid (1 h) starvation cells were stimulated with 2 mM L-leucine and protein synthesis measured using 3H-labelled phenylalanine. Protein breakdown was measured using 3H-labelled phenylalanine and signalling pathways (Akt, mTOR, p70S6k, 4EBP1, rps6 and FOXO3a) via Western blots. Data revealed that after incubation with EPA protein synthesis was 25% greater (P < 0.05) compared to control cells, with no effect of DHA. Protein breakdown was 22% (P < 0.05) lower, compared to control cells, after incubation with EPA, with no effect of DHA. Analysis of signalling pathways revealed that both EPA and DHA incubation increased (P < 0.05) p70s6k phosphorylation, EPA increased (P < 0.05) FOXO3a phosphorylation, with no alteration in other signalling proteins. The current study has demonstrated distinct effects of EPA and DHA on protein metabolism with EPA showing a greater ability to result in skeletal muscle protein accretion

  2. Protein phosphatase 2A regulates central sensitization in the spinal cord of rats following intradermal injection of capsaicin

    Fang Li

    2006-03-01

    Full Text Available Abstract Background Intradermal injection of capsaicin into the hind paw of rats induces spinal cord central sensititzation, a process in which the responsiveness of central nociceptive neurons is amplified. In central sensitization, many signal transduction pathways composed of several cascades of intracellular enzymes are involved. As the phosphorylation state of neuronal proteins is strictly controlled and balanced by the opposing activities of protein kinases and phosphatases, the involvement of phosphatases in these events needs to be investigated. This study is designed to determine the influence of serine/threonine protein phosphatase type 2A (PP2A on the central nociceptive amplification process, which is induced by intradermal injection of capsaicin in rats. Results In experiment 1, the expression of PP2A protein in rat spinal cord at different time points following capsaicin or vehicle injection was examined using the Western blot method. In experiment 2, an inhibitor of PP2A (okadaic acid, 20 nM or fostriecin, 30 nM was injected into the subarachnoid space of the spinal cord, and the spontaneous exploratory activity of the rats before and after capsaicin injection was recorded with an automated photobeam activity system. The results showed that PP2A protein expression in the spinal cord was significantly upregulated following intradermal injection of capsaicin in rats. Capsaicin injection caused a significant decrease in exploratory activity of the rats. Thirty minutes after the injection, this decrease in activity had partly recovered. Infusion of a phosphatase inhibitor into the spinal cord intrathecal space enhanced the central sensitization induced by capsaicin by making the decrease in movement last longer. Conclusion These findings indicate that PP2A plays an important role in the cellular mechanisms of spinal cord central sensitization induced by intradermal injection of capsaicin in rats, which may have implications in

  3. Heart failure-inducible gene therapy targeting protein phosphatase 1 prevents progressive left ventricular remodeling.

    Yosuke Miyazaki

    Full Text Available BACKGROUND: The targeting of Ca(2+ cycling has emerged as a potential therapy for the treatment of severe heart failure. These approaches include gene therapy directed at overexpressing sarcoplasmic reticulum (SR Ca(2+ ATPase, or ablation of phospholamban (PLN and associated protein phosphatase 1 (PP1 protein complexes. We previously reported that PP1β, one of the PP1 catalytic subunits, predominantly suppresses Ca(2+ uptake in the SR among the three PP1 isoforms, thereby contributing to Ca(2+ downregulation in failing hearts. In the present study, we investigated whether heart-failure-inducible PP1β-inhibition by adeno-associated viral-9 (AAV9 vector mediated gene therapy is beneficial for preventing disease progression in genetic cardiomyopathic mice. METHODS: We created an adeno-associated virus 9 (AAV9 vector encoding PP1β short-hairpin RNA (shRNA or negative control (NC shRNA. A heart failure inducible gene expression system was employed using the B-type natriuretic protein (BNP promoter conjugated to emerald-green fluorescence protein (EmGFP and the shRNA sequence. AAV9 vectors (AAV9-BNP-EmGFP-PP1βshRNA and AAV9-BNP-EmGFP-NCshRNA were injected into the tail vein (2×10(11 GC/mouse of muscle LIM protein deficient mice (MLPKO, followed by serial analysis of echocardiography, hemodynamic measurement, biochemical and histological analysis at 3 months. RESULTS: In the MLPKO mice, BNP promoter activity was shown to be increased by detecting both EmGFP expression and the induced reduction of PP1β by 25% in the myocardium. Inducible PP1βshRNA delivery preferentially ameliorated left ventricular diastolic function and mitigated adverse ventricular remodeling. PLN phosphorylation was significantly augmented in the AAV9-BNP-EmGFP-PP1βshRNA injected hearts compared with the AAV9-BNP-EmGFP-NCshRNA group. Furthermore, BNP production was reduced, and cardiac interstitial fibrosis was abrogated at 3 months. CONCLUSION: Heart failure

  4. Coumarins from Angelica decursiva inhibit α-glucosidase activity and protein tyrosine phosphatase 1B.

    Ali, Md Yousof; Jannat, Susoma; Jung, Hyun Ah; Jeong, Hyong Oh; Chung, Hae Young; Choi, Jae Sue

    2016-05-25

    In the present study, we investigated the anti-diabetic potential of six natural coumarins, 4-hydroxy Pd-C-III (1), 4'-methoxy Pd-C-I (2), decursinol (3), decursidin (4), umbelliferone 6-carboxylic acid (5), and 2'-isopropyl psoralene (6) isolated from Angelica decursiva and evaluated their inhibitory activities against protein tyrosine phosphatase 1B (PTP1B), α-glucosidase, and ONOO(-)-mediated protein tyrosine nitration. Coumarins 1-6 showed potent PTP1B and α-glucosidase inhibitory activities with ranges of IC50 values of 5.39-58.90 μM and 65.29-172.10 μM, respectively. In the kinetic study for PTP1B enzyme inhibition, compounds 1, 5, and 6 were competitive, whereas 2 and 4 showed mixed type, and 3 displayed noncompetitive type inhibition. For α-glucosidase enzyme inhibition, compounds 1 and 3 exhibited good mixed-type, while 2, 5, and 6 showed noncompetitive and 4 displayed competitive type inhibition. Furthermore, these coumarins also effectively suppressed ONOO(-)-mediated tyrosine nitration in a dose-dependent manner. To further investigate PTP1B inhibition, we generated a 3D structure of PTP1B using Autodock 4.2 and simulated the binding of compounds 1-6. Docking simulations showed that different residues of PTP1B interacted with different functional groups of compounds 1-6 through hydrogen and hydrophobic interactions. In addition, the binding energies of compounds 1-6 were negative, suggesting that hydrogen bonding may stabilize the open form of the enzyme and potentiate tight binding of the active site of PTP1B, thereby resulting in more effective PTP1B inhibition. These results demonstrate that the whole plant of A. decursiva and its coumarins are useful as potential functional food ingredients for the prevention and treatment of type 2 diabetes. PMID:27085377

  5. Tau pathology involves protein phosphatase 2A in parkinsonism-dementia of Guam.

    Arif, Mohammad; Kazim, Syed Faraz; Grundke-Iqbal, Inge; Garruto, Ralph M; Iqbal, Khalid

    2014-01-21

    Parkinsonism-dementia (PD) of Guam is a neurodegenerative disease with parkinsonism and early-onset Alzheimer-like dementia associated with neurofibrillary tangles composed of hyperphosphorylated microtubule-associated protein, tau. β-N-methylamino-l-alanine (BMAA) has been suspected of being involved in the etiology of PD, but the mechanism by which BMAA leads to tau hyperphosphorylation is not known. We found a decrease in protein phosphatase 2A (PP2A) activity associated with an increase in inhibitory phosphorylation of its catalytic subunit PP2Ac at Tyr(307) and abnormal hyperphosphorylation of tau in brains of patients who had Guam PD. To test the possible involvement of BMAA in the etiopathogenesis of PD, we studied the effect of this environmental neurotoxin on PP2A activity and tau hyperphosphorylation in mouse primary neuronal cultures and metabolically active rat brain slices. BMAA treatment significantly decreased PP2A activity, with a concomitant increase in tau kinase activity resulting in elevated tau hyperphosphorylation at PP2A favorable sites. Moreover, we found an increase in the phosphorylation of PP2Ac at Tyr(307) in BMAA-treated rat brains. Pretreatment with metabotropic glutamate receptor 5 (mGluR5) and Src antagonists blocked the BMAA-induced inhibition of PP2A and the abnormal hyperphosphorylation of tau, indicating the involvement of an Src-dependent PP2A pathway. Coimmunoprecipitation experiments showed that BMAA treatment dissociated PP2Ac from mGluR5, making it available for phosphorylation at Tyr(307). These findings suggest a scenario in which BMAA can lead to tau pathology by inhibiting PP2A through the activation of mGluR5, the consequent release of PP2Ac from the mGluR5-PP2A complex, and its phosphorylation at Tyr(307) by Src. PMID:24395787

  6. Role of protein tyrosine phosphatases in regulating the immune system: implications for chronic intestinal inflammation.

    Spalinger, Marianne R; McCole, Declan F; Rogler, Gerhard; Scharl, Michael

    2015-03-01

    Current hypothesis suggests that genetic, immunological, and bacterial factors contribute essentially to the pathogenesis of inflammatory bowel disease. Variations within the gene loci encoding protein tyrosine phosphatases (PTPs) have been associated with the onset of inflammatory bowel disease. PTPs modulate the activity of their substrates by dephosphorylation of tyrosine residues and are critical for the regulation of fundamental cellular signaling processes. Evidence emerges that expression levels of PTPN2, PTPN11, and PTPN22 are altered in actively inflamed intestinal tissue. PTPN2 seems to be critical for protecting intestinal epithelial barrier function, regulating innate and adaptive immune responses and finally for maintaining intestinal homeostasis. These observations have been confirmed in PTPN2 knockout mice in vivo. Those animals are clearly more susceptible to intestinal and systemic inflammation and feature alterations in innate and adaptive immune responses. PTPN22 controls inflammatory signaling in lymphocytes and mononuclear cells resulting in aberrant cytokine secretion pattern and autophagosome formation. PTPN22 deficiency in vivo results in more severe colitis demonstrating the relevance of PTPN22 for intestinal homeostasis in vivo. Of note, loss of PTPN22 promotes mitogen-activated protein kinase-induced cytokine secretion but limits secretion of nuclear factor κB-associated cytokines and autophagy in mononuclear cells. Loss of PTPN11 is also associated with increased colitis severity in vivo. In summary, dysfunction of those PTPs results in aberrant and uncontrolled immune responses that result in chronic inflammatory conditions. This way, it becomes more and more evident that dysfunction of PTPs displays an important factor in the pathogenesis of chronic intestinal inflammation, in particular inflammatory bowel disease. PMID:25581833

  7. Identification of genomic regions that interact with a viable allele of the Drosophila protein tyrosine phosphatase corkscrew.

    Firth, L; Manchester, J; Lorenzen, J A; Baron, M.; Perkins, L A

    2000-01-01

    Signaling by receptor tyrosine kinases (RTKs) is critical for a multitude of developmental decisions and processes. Among the molecules known to transduce the RTK-generated signal is the nonreceptor protein tyrosine phosphatase Corkscrew (Csw). Previously, Csw has been demonstrated to function throughout the Drosophila life cycle and, among the RTKs tested, Csw is essential in the Torso, Sevenless, EGF, and Breathless/FGF RTK pathways. While the biochemical function of Csw remains to be unamb...

  8. The protein phosphatase PhzA of A. fumigatus is involved in oxidative stress tolerance and fungal virulence

    Muszkieta, Laetitia; de Jesus Carrion, Steven; Robinet, Pauline; Beau, Rémi; Elbim, Carole; Pearlman, Eric; Latgé, Jean-Paul

    2014-01-01

    Protein phosphatases Z that are unique to the fungal kingdom have been associated to resistance to high salt concentration, cell wall integrity, cell cycle regulation, and oxidative stress in fungi. In Aspergillus fumigatus it was shown that PHZA is under the control of the transcription factor Skn7 and is only involved in the control of the oxidative stress. Accordingly, the ΔphzA mutant showed a defect in virulence in an experimental model of corneal infection in immuno...

  9. Force-inhibiting effect of Ser/Thr protein phosphatase 2A inhibitors on bovine ciliary muscle.

    石田, 美織

    2015-01-01

    Ciliary muscle is a smooth muscle characterized by a rapid response to muscarinic receptor stimulation and sustained contraction. Although it is evident that these contractions are Ca(2+)-dependent, detailed molecular mechanisms are still unknown. In order to elucidate the role of Ser/Thr protein phosphatase 2A (PP2A) in ciliary muscle contraction, we examined the effects of okadaic acid and other PP2A inhibitors on contractions induced by carbachol (CCh) and ionomycin in bovine ciliary muscl...

  10. Homo sapiens Dullard Protein Phosphatase Shows Preference Toward Insulin-dependent Phosphorylation Site of Lipin1†

    Wu, Rui; Garland, Megan; Dunaway-Mariano, Debra; Allen, Karen N.

    2011-01-01

    Human lipin1 catalyzes the highly regulated conversion of phosphatidic acids to diacylglycerides. Lipin’s cellular location, protein partners, and biological function are directed by phosphorylation/dephosphorylation events catalyzed by the phosphoserine phosphatase dullard. To define the determinants of dullard substrate recognition and catalysis, and hence, lipin regulation, steady-state kinetic analysis was performed on phosphoserine-bearing nonapeptides based on the phosphorylation sites ...

  11. Functional dissection of T. brucei Protein Tyrosine Phosphatase 1 and investigation of its development as a therapeutic target

    Ruberto, Irene

    2011-01-01

    Trypanosoma brucei undergoes developmentally regulated morphological and biochemical changes during its life cycle, being transmitted between the mammalian host and the tsetse fly. It is generally recognized that cellular responses to environmental changes are mediated through signalling pathways, but our understanding of trypanosome signal transduction during differentiation is limited. Protein Tyrosine Phosphatase 1 (TbPTP1) is the one of the few factors identified to b...

  12. Rif1 controls DNA replication by directing Protein Phosphatase 1 to reverse Cdc7-mediated phosphorylation of the MCM complex

    Hiraga, Shin-ichiro; Alvino, Gina M.; Chang, FuJung; Lian, Hui-Yong; Sridhar, Akila; Kubota, Takashi; Brewer, Bonita J.; Weinreich, Michael; Raghuraman, M. K.; Donaldson, Anne D.

    2014-01-01

    Recent evidence points to a role for Rif1 (Rap1-interacting factor) in DNA replication and genomic stability; however, the mechanism by which Rif1 functions has remained elusive. Hiraga el al. now report that budding yeast Rif1 controls DNA replication genome-wide and describe how Rif1 opposes Dbf4-dependent kinase (DDK) function by directing Protein Phosphatase 1 (PP1)-mediated dephosphorylation of the MCM complex. PP1 interaction sites are evolutionarily conserved within the Rif1 sequence; ...

  13. SRK2C, a SNF1-related protein kinase 2, improves drought tolerance by controlling stress-responsive gene expression in Arabidopsis thaliana

    Umezawa, Taishi; Yoshida, Riichiro; Maruyama, Kyonoshin; Yamaguchi-Shinozaki, Kazuko; Shinozaki, Kazuo

    2004-01-01

    Protein phosphorylation/dephosphorylation are major signaling events induced by osmotic stress in higher plants. Here, we showed that a SNF1-related protein kinase 2 (SnRK2), SRK2C, is an osmotic-stress-activated protein kinase in Arabidopsis thaliana that can significantly impact drought tolerance of Arabidopsis plants. Knockout mutants of SRK2C exhibited drought hypersensitivity in their roots, suggesting that SRK2C is a positive regulator of drought tolerance in Arabidopsis roots. Addition...

  14. Protein phosphatases PP2A, PP4 and PP6: mediators and regulators in development and responses to environmental cues.

    Lillo, Cathrine; Kataya, Amr R A; Heidari, Behzad; Creighton, Maria T; Nemie-Feyissa, Dugassa; Ginbot, Zekarias; Jonassen, Else M

    2014-12-01

    The three closely related groups of serine/threonine protein phosphatases PP2A, PP4 and PP6 are conserved throughout eukaryotes. The catalytic subunits are present in trimeric and dimeric complexes with scaffolding and regulatory subunits that control activity and confer substrate specificity to the protein phosphatases. In Arabidopsis, three scaffolding (A subunits) and 17 regulatory (B subunits) proteins form complexes with five PP2A catalytic subunits giving up to 255 possible combinations. Three SAP-domain proteins act as regulatory subunits of PP6. Based on sequence similarities with proteins in yeast and mammals, two putative PP4 regulatory subunits are recognized in Arabidopsis. Recent breakthroughs have been made concerning the functions of some of the PP2A and PP6 regulatory subunits, for example the FASS/TON2 in regulation of the cellular skeleton, B' subunits in brassinosteroid signalling and SAL proteins in regulation of auxin transport. Reverse genetics is starting to reveal also many more physiological functions of other subunits. A system with key regulatory proteins (TAP46, TIP41, PTPA, LCMT1, PME-1) is present in all eukaryotes to stabilize, activate and inactivate the catalytic subunits. In this review, we present the status of knowledge concerning physiological functions of PP2A, PP4 and PP6 in Arabidopsis, and relate these to yeast and mammals. PMID:24810976

  15. Nuclear Export and Centrosome Targeting of the Protein Phosphatase 2A Subunit B56α

    Flegg, Cameron P.; Sharma, Manisha; Medina-Palazon, Cahora; Jamieson, Cara; Galea, Melanie; Brocardo, Mariana G.; Mills, Kate; Henderson, Beric R.

    2010-01-01

    Protein phosphatase (PP) 2A is a heterotrimeric enzyme regulated by specific subunits. The B56 (or B′/PR61/PPP2R5) class of B-subunits direct PP2A or its substrates to different cellular locations, and the B56α, -β, and -ϵ isoforms are known to localize primarily in the cytoplasm. Here we studied the pathways that regulate B56α subcellular localization. We detected B56α in the cytoplasm and nucleus, and at the nuclear envelope and centrosomes, and show that cytoplasmic localization is dependent on CRM1-mediated nuclear export. The inactivation of CRM1 by leptomycin B or by siRNA knockdown caused nuclear accumulation of ectopic and endogenous B56α. Conversely, CRM1 overexpression shifted B56α to the cytoplasm. We identified a functional nuclear export signal at the C terminus (NES; amino acids 451–469), and site-directed mutagenesis of the NES (L461A) caused nuclear retention of full-length B56α. Active NESs were identified at similar positions in the cytoplasmic B56-β and ϵ isoforms, but not in the nuclear-localized B56-δ or γ isoforms. The transient expression of B56α induced nuclear export of the PP2A catalytic (C) subunit, and this was blocked by the L461A NES mutation. In addition, B56α co-located with the PP2A active (A) subunit at centrosomes, and its centrosome targeting involved sequences that bind to the A-subunit. Fluorescence Recovery after Photobleaching (FRAP) assays revealed dynamic and immobile pools of B56α-GFP, which was rapidly exported from the nucleus and subject to retention at centrosomes. We propose that B56α can act as a PP2A C-subunit chaperone and regulates PP2A activity at diverse subcellular locations. PMID:20378546

  16. Protein phosphatase 2A regulatory subunits perform distinct functional roles in the maize pathogen Fusarium verticillioides.

    Shin, Joon-Hee; Kim, Jung-Eun; Malapi-Wight, Martha; Choi, Yoon-E; Shaw, Brian D; Shim, Won-Bo

    2013-06-01

    Fusarium verticillioides is a pathogen of maize causing ear rot and stalk rot. The fungus also produces fumonisins, a group of mycotoxins linked to disorders in animals and humans. A cluster of genes, designated FUM genes, plays a key role in the synthesis of fumonisins. However, our understanding of the regulatory mechanism of fumonisin biosynthesis is still incomplete. We have demonstrated previously that Cpp1, a protein phosphatase type 2A (PP2A) catalytic subunit, negatively regulates fumonisin production and is involved in cell shape maintenance. In general, three PP2A subunits, structural A, regulatory B and catalytic C, make up a heterotrimer complex to perform regulatory functions. Significantly, we identified two PP2A regulatory subunits in the F. verticillioides genome, Ppr1 and Ppr2, which are homologous to Saccharomyces cerevisiae Cdc55 and Rts1, respectively. In this study, we hypothesized that Ppr1 and Ppr2 are involved in the regulation of fumonisin biosynthesis and/or cell development in F. verticillioides, and generated a series of mutants to determine the functional role of Ppr1 and Ppr2. The PPR1 deletion strain (Δppr1) resulted in drastic growth defects, but increased microconidia production. The PPR2 deletion mutant strain (Δppr2) showed elevated fumonisin production, similar to the Δcpp1 strain. Germinating Δppr1 conidia formed abnormally swollen cells with a central septation site, whereas Δppr2 showed early hyphal branching during conidia germination. A kernel rot assay showed that the mutants were slow to colonize kernels, but this is probably a result of growth defects rather than a virulence defect. Results from this study suggest that two PP2A regulatory subunits in F. verticillioides carry out distinct roles in the regulation of fumonisin biosynthesis and fungal development. PMID:23452277

  17. Regulation of brown fat adipogenesis by protein tyrosine phosphatase 1B.

    Kosuke Matsuo

    Full Text Available Protein-tyrosine phosphatase 1B (PTP1B is a physiological regulator of insulin signaling and energy balance, but its role in brown fat adipogenesis requires additional investigation.To precisely determine the role of PTP1B in adipogenesis, we established preadipocyte cell lines from wild type and PTP1B knockout (KO mice. In addition, we reconstituted KO cells with wild type, substrate-trapping (D/A and sumoylation-resistant (K/R PTP1B mutants, then characterized differentiation and signaling in these cells. KO, D/A- and WT-reconstituted cells fully differentiated into mature adipocytes with KO and D/A cells exhibiting a trend for enhanced differentiation. In contrast, K/R cells exhibited marked attenuation in differentiation and lipid accumulation compared with WT cells. Expression of adipogenic markers PPARγ, C/EBPα, C/EBPδ, and PGC1α mirrored the differentiation pattern. In addition, the differentiation deficit in K/R cells could be reversed completely by the PPARγ activator troglitazone. PTP1B deficiency enhanced insulin receptor (IR and insulin receptor substrate 1 (IRS1 tyrosyl phosphorylation, while K/R cells exhibited attenuated insulin-induced IR and IRS1 phosphorylation and glucose uptake compared with WT cells. In addition, substrate-trapping studies revealed that IRS1 is a substrate for PTP1B in brown adipocytes. Moreover, KO, D/A and K/R cells exhibited elevated AMPK and ACC phosphorylation compared with WT cells.These data indicate that PTP1B is a modulator of brown fat adipogenesis and suggest that adipocyte differentiation requires regulated expression of PTP1B.

  18. Protein tyrosine phosphatase receptor delta acts as a neuroblastoma tumor suppressor by destabilizing the aurora kinase a oncogene

    Meehan, Maria

    2012-02-05

    Abstract Background Protein tyrosine phosphatase receptor delta (PTPRD) is a member of a large family of protein tyrosine phosphatases which negatively regulate tyrosine phosphorylation. Neuroblastoma is a major childhood cancer arising from precursor cells of the sympathetic nervous system which is known to acquire deletions and alterations in the expression patterns of PTPRD, indicating a potential tumor suppressor function for this gene. The molecular mechanism, however, by which PTPRD renders a tumor suppressor effect in neuroblastoma is unknown. Results As a molecular mechanism, we demonstrate that PTPRD interacts with aurora kinase A (AURKA), an oncogenic protein that is over-expressed in multiple forms of cancer, including neuroblastoma. Ectopic up-regulation of PTPRD in neuroblastoma dephosphorylates tyrosine residues in AURKA resulting in a destabilization of this protein culminating in interfering with one of AURKA\\'s primary functions in neuroblastoma, the stabilization of MYCN protein, the gene of which is amplified in approximately 25 to 30% of high risk neuroblastoma. Conclusions PTPRD has a tumor suppressor function in neuroblastoma through AURKA dephosphorylation and destabilization and a downstream destabilization of MYCN protein, representing a novel mechanism for the function of PTPRD in neuroblastoma.

  19. Molecular dynamics simulations of protein-tyrosine phosphatase 1B: II. Substrate-enzyme interactions and dynamics

    Peters, Günther H.j.; Frimurer, T. M.; Andersen, J. N.; Olsen, O. H.

    2000-01-01

    Molecular dynamics simulations of protein tyrosine phosphatase 1B (PTP1B) complexed with the phosphorylated peptide substrate DADEpYL and the free substrate have been conducted to investigate 1) the physical forces involved in substrate-protein interactions, 2) the importance of enzyme and...... substrate binding. Based on essential dynamics analysis of the PTP1B/DADEpYL trajectory, it is shown that internal motions in the binding pocket occur in a subspace of only a few degrees of freedom. in particular, relatively large flexibilities are observed along several eigenvectors in the segments: Arg(24...

  20. Interaction of the Papillomavirus E8∧E2C Protein with the Cellular CHD6 Protein Contributes to Transcriptional Repression▿ †

    Fertey, Jasmin; Ammermann, Ingo; Winkler, Michael; Stöger, Reinhard; Iftner, Thomas; Stubenrauch, Frank

    2010-01-01

    Expression of the E6 and E7 oncogenes of high-risk human papillomaviruses (HPV) is controlled by cellular transcription factors and by viral E2 and E8∧E2C proteins, which are both derived from the HPV E2 gene. Both proteins bind to and repress the HPV E6/E7 promoter. Promoter inhibition has been suggested to be due to binding site competition with cellular transcription factors and to interactions of different cellular transcription modulators with the different amino termini of E2 and E8∧E2C...

  1. Analysis of Two Putative Candida albicans Phosphopantothenoylcysteine Decarboxylase / Protein Phosphatase Z Regulatory Subunits Reveals an Unexpected Distribution of Functional Roles

    Petrényi, Katalin; Molero, Cristina; Kónya, Zoltán; Erdődi, Ferenc; Ariño, Joaquin; Dombrádi, Viktor

    2016-01-01

    Protein phosphatase Z (Ppz) is a fungus specific enzyme that regulates cell wall integrity, cation homeostasis and oxidative stress response. Work on Saccharomyces cerevisiae has shown that the enzyme is inhibited by Hal3/Vhs3 moonlighting proteins that together with Cab3 constitute the essential phosphopantothenoylcysteine decarboxylase (PPCDC) enzyme. In Candida albicans CaPpz1 is also involved in the morphological changes and infectiveness of this opportunistic human pathogen. To reveal the CaPpz1 regulatory context we searched the C. albicans database and identified two genes that, based on the structure of their S. cerevisiae counterparts, were termed CaHal3 and CaCab3. By pull down analysis and phosphatase assays we demonstrated that both of the bacterially expressed recombinant proteins were able to bind and inhibit CaPpz1 as well as its C-terminal catalytic domain (CaPpz1-Cter) with comparable efficiency. The binding and inhibition were always more pronounced with CaPpz1-Cter, indicating a protective effect against inhibition by the N-terminal domain in the full length protein. The functions of the C. albicans proteins were tested by their overexpression in S. cerevisiae. Contrary to expectations we found that only CaCab3 and not CaHal3 rescued the phenotypic traits that are related to phosphatase inhibition by ScHal3, such as tolerance to LiCl or hygromycin B, requirement for external K+ concentrations, or growth in a MAP kinase deficient slt2 background. On the other hand, both of the Candida proteins turned out to be essential PPCDC components and behaved as their S. cerevisiae counterparts: expression of CaCab3 and CaHal3 rescued the cab3 and hal3 vhs3 S. cerevisiae mutations, respectively. Thus, both CaHal3 and CaCab3 retained the PPCDC related functions and have the potential for CaPpz1 inhibition in vitro. The fact that only CaCab3 exhibits its phosphatase regulatory potential in vivo suggests that in C. albicans CaCab3, but not CaHal3, acts as a

  2. Archaeal signal transduction: impact of protein phosphatase deletions on cell size, motility, and energy metabolism in Sulfolobus acidocaldarius.

    Reimann, Julia; Esser, Dominik; Orell, Alvaro; Amman, Fabian; Pham, Trong Khoa; Noirel, Josselin; Lindås, Ann-Christin; Bernander, Rolf; Wright, Phillip C; Siebers, Bettina; Albers, Sonja-Verena

    2013-12-01

    In this study, the in vitro and in vivo functions of the only two identified protein phosphatases, Saci-PTP and Saci-PP2A, in the crenarchaeal model organism Sulfolobus acidocaldarius were investigated. Biochemical characterization revealed that Saci-PTP is a dual-specific phosphatase (against pSer/pThr and pTyr), whereas Saci-PP2A exhibited specific pSer/pThr activity and inhibition by okadaic acid. Deletion of saci_pp2a resulted in pronounced alterations in growth, cell shape and cell size, which could be partially complemented. Transcriptome analysis of the three strains (Δsaci_ptp, Δsaci_pp2a and the MW001 parental strain) revealed 155 genes that were differentially expressed in the deletion mutants, and showed significant changes in expression of genes encoding the archaella (archaeal motility structure), components of the respiratory chain and transcriptional regulators. Phosphoproteome studies revealed 801 unique phosphoproteins in total, with an increase in identified phosphopeptides in the deletion mutants. Proteins from most functional categories were affected by phosphorylation, including components of the motility system, the respiratory chain, and regulatory proteins. In the saci_pp2a deletion mutant the up-regulation at the transcript level, as well as the observed phosphorylation pattern, resembled starvation stress responses. Hypermotility was also observed in the saci_pp2a deletion mutant. The results highlight the importance of protein phosphorylation in regulating essential cellular processes in the crenarchaeon S. acidocaldarius. PMID:24078887

  3. Characterization of Saccharomyces cerevisiae protein Ser/Thr phosphatase T1 and comparison to its mammalian homolog PP5

    Park Jung-Min

    2003-03-01

    Full Text Available Abstract Background Protein Ser/Thr phosphatase 5 (PP5 and its Saccharomyces cerevisiae homolog protein phosphatase T1 (Ppt1p each contain an N-terminal domain consisting of several tetratricopeptide repeats (TPRs and a C-terminal catalytic domain that is related to the catalytic subunits of protein phosphatases 1 and 2A, and calcineurin. Analysis of yeast Ppt1p could provide important clues to the function of PP5 and its homologs, however it has not yet been characterized at the biochemical or cellular level. Results The specific activity of recombinant Ppt1p toward the artificial substrates 32P-myelin basic protein (MBP and 32P-casein was similar to that of PP5. Dephosphorylation of 32P-MBP, but not 32P-casein, was stimulated by unsaturated fatty acids and by arachidoyl coenzyme A. Limited proteolysis of Ppt1p removed the TPR domain and abrogated lipid stimulation. The remaining catalytic fragment exhibited a two-fold increase in activity toward 32P-MBP, but not 32P-casein. Removal of the C terminus increased Ppt1p activity toward both substrates two fold, but did not prevent further stimulation of activity toward 32P-MBP by lipid treatment. Ppt1p was localized throughout the cell including the nucleus. Levels of PPT1 mRNA and protein peaked in early log phase growth. Conclusions Many characteristics of Ppt1p are similar to those of PP5, including stimulation of phosphatase activity with some substrates by lipids, and peak expression during periods of rapid cell growth. Unlike PP5, however, proteolytic removal of the TPR domain or C-terminal truncation only modestly increased its activity. In addition, C-terminal truncation did not prevent further activation by lipid. This suggests that these regions play only a minor role in controlling its activity compared to PP5. Ppt1p is present in both the nucleus and cytoplasm, indicating that it may function in multiple compartments. The observation that Ppt1p is most highly expressed during early log

  4. Cardiac sodium channel Na(v)1.5 interacts with and is regulated by the protein tyrosine phosphatase PTPH1

    Jespersen, Thomas; Gavillet, Bruno; van Bemmelen, Miguel X; Cordonier, Sophie; Thomas, Marc A; Staub, Olivier; Abriel, Hugues

    2006-01-01

    In order to identify proteins interacting with the cardiac voltage-gated sodium channel Na(v)1.5, we used the last 66 amino acids of the C-terminus of the channel as bait to screen a human cardiac cDNA library. We identified the protein tyrosine phosphatase PTPH1 as an interacting protein. Pull-d...

  5. Regulation of Platelet Derived Growth Factor Signaling by Leukocyte Common Antigen-related (LAR) Protein Tyrosine Phosphatase: A Quantitative Phosphoproteomics Study.

    Sarhan, Adil R; Patel, Trushar R; Creese, Andrew J; Tomlinson, Michael G; Hellberg, Carina; Heath, John K; Hotchin, Neil A; Cunningham, Debbie L

    2016-06-01

    Intracellular signaling pathways are reliant on protein phosphorylation events that are controlled by a balance of kinase and phosphatase activity. Although kinases have been extensively studied, the role of phosphatases in controlling specific cell signaling pathways has been less so. Leukocyte common antigen-related protein (LAR) is a member of the LAR subfamily of receptor-like protein tyrosine phosphatases (RPTPs). LAR is known to regulate the activity of a number of receptor tyrosine kinases, including platelet-derived growth factor receptor (PDGFR). To gain insight into the signaling pathways regulated by LAR, including those that are PDGF-dependent, we have carried out the first systematic analysis of LAR-regulated signal transduction using SILAC-based quantitative proteomic and phosphoproteomic techniques. We haveanalyzed differential phosphorylation between wild-type mouse embryo fibroblasts (MEFs) and MEFs in which the LAR cytoplasmic phosphatase domains had been deleted (LARΔP), and found a significant change in abundance of phosphorylation on 270 phosphosites from 205 proteins because of the absence of the phosphatase domains of LAR. Further investigation of specific LAR-dependent phosphorylation sites and enriched biological processes reveal that LAR phosphatase activity impacts on a variety of cellular processes, most notably regulation of the actin cytoskeleton. Analysis of putative upstream kinases that may play an intermediary role between LAR and the identified LAR-dependent phosphorylation events has revealed a role for LAR in regulating mTOR and JNK signaling. PMID:27074791

  6. Selective Serotonin Reuptake Inhibitor Fluoxetine Inhibits Replication of Human Enteroviruses B and D by Targeting Viral Protein 2C

    Ulferts, R.; van der Linden, L.; Thibaut, H.J.; Lanke, K. H. W.; Leyssen, P.; Coutard, B.; De Palma, A.M.; Canard, B; Neyts, J.; Van Kuppeveld, F. J. M.

    2013-01-01

    Although the genus Enterovirus contains many important human pathogens, there is no licensed drug for either the treatment or the prophylaxis of enterovirus infections. We report that fluoxetine (Prozac)-a selective serotonin reuptake inhibitor-inhibits the replication of human enterovirus B (HEV-B) and HEV-D but does not affect the replication of HEV-A and HEV-C or human rhinovirus A or B. We show that fluoxetine interferes with viral RNA replication, and we identified viral protein 2C as th...

  7. Organization and alternate splice products of the gene encoding nuclear inhibitor of protein phosphatase-1 (NIPP-1).

    Van Eynde, A; Pérez-Callejón, E; Schoenmakers, E; Jacquemin, M; Stalmans, W; Bollen, M

    1999-04-01

    Nuclear inhibitor of protein phosphatase-1 (NIPP-1) is one of two major regulatory subunits of protein phosphatase-1 in mammalian nuclei. We report here the cloning and structural characterization of the human NIPP-1 genes, designated PPP1R8P and PPP1R8 in human gene nomenclature. PPP1R8P (1.2 kb) is a processed pseudogene and was localized by in situ hybridization to chromosome 1p33-32. PPP1R8 is an authentic NIPP-1 gene and was localized to chromosome 1p35. PPP1R8 (25.2 kb) is composed of seven exons and encodes four different transcripts, as determined from cDNA library screening, reverse transcriptase-PCR (RT-PCR) and/or EST (expressed sequence tag) database search analysis. NIPP-1alpha mRNA represents the major transcript in human tissues and various cell lines, and encodes a polypeptide of 351 residues that only differs from the previously cloned calf thymus NIPP-1 by a single residue. The other transcripts, termed NIPP-1beta, gamma and delta, are generated by alternative 5'-splice site usage, by exon skipping and/or by alternative polyadenylation. The NIPP-1beta/delta and NIPP-1gamma mRNAs are expected to encode fragments of NIPP-1alpha that differ from the latter by the absence of the first 142 and 224 residues, respectively. NIPP-1gamma corresponds to 'activator of RNA decay-1' (Ard-1) which, unlike NIPP-1alpha, displays in vitro and endoribonuclease activity and lacks an RVXF consensus motif for interaction with protein phosphatase-1. While the NIPP-1alpha/beta/delta-transcripts were found to be present in various human tissues, the NIPP-1gamma transcript could only be detected in human transformed B-lymphocytes. PMID:10103062

  8. Applying a Targeted Label-free Approach using LC-MS AMT Tags to Evaluate Changes in Protein Phosphorylation Following Phosphatase Inhibition

    Yang, Feng; Jaitly, Navdeep; Jayachandran, Hemalatha; Lou, Quanzhou; Monroe, Matthew E.; Du, Xiuxia; Gritsenko, Marina A.; Zhang, Rui; Anderson, David J.; Purvine, Samuel O.; Adkins, Joshua N.; Moore, Ronald J.; Mottaz, Heather M.; Ding, Shi-Jian; Lipton, Mary S.; Camp, David G.; Udseth, Harold R.; Smith, Richard D.; Rossie, Sandra S.

    2007-10-12

    To identify phosphoproteins regulated by the phosphoprotein phosphatase (PPP) family of S/T phosphatases, we performed a large-scale characterization of changes in protein phosphorylation on extracts from HeLa cells treated with or without calyculin A, a potent PPP enzyme inhibitor. A label-free comparative Phosphoproteomics approach using immobilized metal ion affinity chromatography and targeted tandem mass spectrometry was employed to discover and identify signatures based upon distinctive changes in abundance. Overall, 232 proteins were identified as either direct or indirect targets for PPP enzyme regulation. Most of the present identifications represent novel PPP enzyme targets at the level of both phosphorylation site and protein. These include phosphorylation sites within signaling proteins such as p120 Catenin, A Kinase Anchoring Protein 8, JunB, and Type II Phosphatidyl Inositol 4 Kinase. These data can be used to define underlying signaling pathways and events regulated by the PPP family of S/T phosphatases.

  9. Electronic structural flexibility of heterobimetallic Mn/Fe cofactors: R2lox and R2c proteins.

    Shafaat, Hannah S; Griese, Julia J; Pantazis, Dimitrios A; Roos, Katarina; Andersson, Charlotta S; Popović-Bijelić, Ana; Gräslund, Astrid; Siegbahn, Per E M; Neese, Frank; Lubitz, Wolfgang; Högbom, Martin; Cox, Nicholas

    2014-09-24

    The electronic structure of the Mn/Fe cofactor identified in a new class of oxidases (R2lox) described by Andersson and Högbom [Proc. Natl. Acad. Sci. U.S.A. 2009, 106, 5633] is reported. The R2lox protein is homologous to the small subunit of class Ic ribonucleotide reductase (R2c) but has a completely different in vivo function. Using multifrequency EPR and related pulse techniques, it is shown that the cofactor of R2lox represents an antiferromagnetically coupled Mn(III)/Fe(III) dimer linked by a μ-hydroxo/bis-μ-carboxylato bridging network. The Mn(III) ion is coordinated by a single water ligand. The R2lox cofactor is photoactive, converting into a second form (R2loxPhoto) upon visible illumination at cryogenic temperatures (77 K) that completely decays upon warming. This second, unstable form of the cofactor more closely resembles the Mn(III)/Fe(III) cofactor seen in R2c. It is shown that the two forms of the R2lox cofactor differ primarily in terms of the local site geometry and electronic state of the Mn(III) ion, as best evidenced by a reorientation of its unique (55)Mn hyperfine axis. Analysis of the metal hyperfine tensors in combination with density functional theory (DFT) calculations suggests that this change is triggered by deprotonation of the μ-hydroxo bridge. These results have important consequences for the mixed-metal R2c cofactor and the divergent chemistry R2lox and R2c perform. PMID:25153930

  10. Improved Glucose Homeostasis in Mice with Muscle-Specific Deletion of Protein-Tyrosine Phosphatase 1B▿

    Delibegovic, Mirela; Bence, Kendra K.; Mody, Nimesh; Hong, Eun-Gyoung; Ko, Hwi Jin; Jason K Kim; Kahn, Barbara B.; Neel, Benjamin G

    2007-01-01

    Obesity and type 2 diabetes are characterized by insulin resistance. Mice lacking the protein-tyrosine phosphatase PTP1B in all tissues are hypersensitive to insulin but also have diminished fat stores. Because adiposity affects insulin sensitivity, the extent to which PTP1B directly regulates glucose homeostasis has been unclear. We report that mice lacking PTP1B only in muscle have body weight and adiposity comparable to those of controls on either chow or a high-fat diet (HFD). Muscle trig...

  11. Inhibitor-3 ensures bipolar mitotic spindle attachment by limiting association of SDS22 with kinetochore-bound protein phosphatase-1

    Eiteneuer, Annika; Seiler, Jonas; Weith, Matthias; Beullens, Monique; Lesage, Bart; Krenn, Veronica; Musacchio, Andrea; Bollen, Mathieu; Meyer, Hemmo

    2014-01-01

    Faithful chromosome segregation during mitosis is tightly regulated by opposing activities of Aurora B kinase and protein phosphatase-1 (PP1). PP1 function at kinetochores has been linked to SDS22, but the exact localization of SDS22 and how it affects PP1 are controversial. Here, we confirm that SDS22 is required for PP1 activity, but show that SDS22 does not normally localize to kinetochores. Instead, SDS22 is kept in solution by formation of a ternary complex with PP1 and inhibitor-3 (I3)....

  12. A Rapid Lateral Flow Immunoassay for the Detection of Tyrosine Phosphatase-Like Protein IA-2 Autoantibodies in Human Serum

    Ingrid Kikkas; Roberto Mallone; Etienne Larger; Hervé Volland; Nathalie Morel

    2014-01-01

    Type 1 diabetes (T1D) results from the destruction of pancreatic insulin-producing beta cells and is strongly associated with the presence of islet autoantibodies. Autoantibodies to tyrosine phosphatase-like protein IA-2 (IA-2As) are considered to be highly predictive markers of T1D. We developed a novel lateral flow immunoassay (LFIA) based on a bridging format for the rapid detection of IA-2As in human serum samples. In this assay, one site of the IA-2As is bound to HA-tagged-IA-2, which is...

  13. Time dependent physiological characterization of yeast oxidative stress response and growth modulation of protein kinase/phosphatase mutants

    Altintas, Ali; Workman, Christopher

    mutants were selected for their known activities in various stress response pathways, including oxidative stress, and were investigated for their response to oxidative stress. Hydrogen peroxide was us ed as the oxidizing agent at a number of different concentrations ranging from mild to moderate stress (0......The objective of the project was to investigate the time-dependent batch growth effects of oxidative environmental conditions on protein ki nase (PK) and phosphatase (PP) deletion mutants and relevant wild type strains of Saccharomyces cerevisiae . To achieve this goal, 44 different PK and PP...

  14. Characterization of an adapter subunit to a phosphatidylinositol (3)P 3-phosphatase: Identification of a myotubularin-related protein lacking catalytic activity

    Nandurkar, H. H.; Caldwell, K K; Whisstock, J C; Layton, M. J.; Gaudet, E. A.; Norris, F. A.; Majerus, P W; Mitchell, C. A.

    2001-01-01

    The D3-phosphoinositides act as second messengers by recruiting, and thereby activating, diverse signaling proteins. We have previously described the purification of a rat phosphatidylinositol 3-phosphate [PtdIns(3)P] 3-phosphatase, comprising a heterodimer of a 78-kDa adapter subunit in complex with a 65-kDa catalytic subunit. Here, we have cloned and characterized the cDNA encoding the human 3-phosphatase adapter subunit (3-PAP). Sequence alignment showed that 3-PAP ...

  15. Identification and characterization of novel membrane-bound PRL protein tyrosine phosphatases from Setaria cervi, a bovine filarial parasite.

    Singh, Neetu; Yadav, Smita; Rathaur, Sushma

    2015-11-01

    A significant amount of protein tyrosine phosphatase (PTP) activity was detected in the detergent-soluble membrane-bound fraction of Setaria cervi, a bovine filarial parasite. The membrane-bound PTP activity was significantly inhibited when the adult parasites were exposed to compounds having antifilarial activity like aspirin and SK7 as well as phenylarsine oxide, a specific PTP inhibitor suggesting that this activity is stress regulated. Further, this enzyme was purified as a single protein of apparently 21 kDa using two different chromatographic techniques. The MALDI-MS/MS analysis of its peptides showed closest match with protein tyrosine phosphatase PRL (Aedes aegypti). This purified enzyme (named as PRL) showed maximum activity at pH 5.5/37 °C and hydrolysed para nitro phenyl phosphate (pNPP) at the highest rate followed by O-P-L-tyrosine and O-P-L-threonine. It showed significant inhibition by specific inhibitors of PTP such as sodium orthovanadate, phenylarsine oxide and ammonium molybdate and was activated by dithiothreitol (DTT). The active site modification studies suggested involvement of cysteine, arginine, histidine and aspartic acid in the catalytic activity of PRL. The activity of S. cervi PRL was also found to be resistant towards the external oxidative stress. Thus, S. cervi PRL could be taken as a potential target for the management of human lymphatic filariasis. PMID:26341797

  16. Characterization of a eukaryotic type serine/threonine protein kinase and protein phosphatase of Streptococcus pneumoniae and identification of kinase substrates

    Nováková, Linda; Přenosilová, Lenka; Pallová, Petra; Janeček, Jiří; Novotná, Jana; Ulrych, Aleš; Echenique, J.; Trombe, M.-C.; Branny, Pavel

    2005-01-01

    Roč. 272, - (2005), s. 1243-1254. E-ISSN 1742-4658 R&D Projects: GA ČR GA204/99/1534; GA ČR GA204/02/1423 Grant ostatní: UK 188/2004/B-BIO/PrF Institutional research plan: CEZ:AV0Z50200510 Keywords : phosphoglucosamine mutase * phosphoproteome * protein phosphatase Subject RIV: EE - Microbiology, Virology

  17. Gene order for rubella virus structural proteins is NH/sub 2/-C-E2-E1-COOH

    Oker-Blom, C.

    1984-08-01

    The order of translation in vivo of the genes coding for rubella virus structural proteins was studied in infected B-Vero cells. The proteins were sequentially pulse-chase labeled with (/sup 35/S)methionine after synchronization of translation initiation with hypertonic salt treatment. A sequential labeling procedure (window-labeling) to specifically label defined segments of the structural proteins was also used. The labeled proteins were identified by sodium dodecyl sulfate-gel electrophoresis after immunoprecipitation with specific antisera directed against the two virion glycoproteins (E1 and E2a/E2b) and the nucleocapsid (C) protein. The order of translation was found to be NH/sub 2/-C-E2-E1-COOH. We have previously shown that the structural proteins are synthesized in vitro from a cytoplasmic 24S subgenomic mRNA as a 110,000-dalton (p110) precursor. Here, it is shown that p110 is precipitated with anti-C, anti-E2, and anti-E1 sera, indicating that p110 is the precursor of all three structural proteins. Two major in vitro translation products (M/sub r/s, 66,000 and 62,000) that could represent preterminated polypeptide chains or proteolytic cleavage products were precipitated with anti-C and anti-Es sera, but not with anti-E1 serum, indicating, in conformity with the in vivo results, that the genes for the C and E2 proteins are adjacent to each other. Using these specific antisera, we have also confirmed the identity of the unglycosylated forms of E1 (M/sub r/, 53,000) and E2 (M/sub r/ 30,000) immunoprecipitated from tunicamycin-treated infected cells. 18 references, 6 figures.

  18. Cathepsin D-mediated yolk protein degradation is blocked by acid phosphatase inhibitors.

    Fialho, Eliane; Nakamura, Angelica; Juliano, Luiz; Masuda, Hatisaburo; Silva-Neto, Mário A C

    2005-04-15

    Vitellin (VT) is a lipoglycophosphoprotein stored inside the eggs of every oviparous organism during oogenesis. In the blood-sucking bug Rhodnius prolixus, VT is deposited inside growing oocytes together with two acid hydrolases: acid phosphatase (AP) and cathepsin D (CD). Egg fertilization triggers AP activity and VT proteolysis in vivo [Insect Biochem. Mol. Biol. 2002 (32) 847]. Here, we show that CD is the main protease targeting VT proteolysis during egg development. CD activity in total egg homogenates is blocked by the classical aspartyl protease inhibitor, pepstatin A. Surprisingly, AP inhibitors such as NaF, Na+/K+ tartrate, and inorganic phosphate also block VT proteolysis, whereas this effect is not observed when tyrosine phosphatase inhibitors such as vanadate and phenylarsine oxide or an inhibitor of alkaline phosphatases such as levamisole are used in a VT proteolysis assay. NaF concentrations that block isolated AP activity do not affect the activity of partially purified CD. Therefore, a specific repressor of VT proteolysis must be dephosphorylated by AP in vivo. In conclusion, these results demonstrate for the first time that acid hydrolases act cooperatively to promote yolk degradation during egg development in arthropods. PMID:15797237

  19. Implication of protein tyrosine phosphatase 1B in MCF-7 cell proliferation and resistance to 4-OH tamoxifen

    Blanquart, Christophe; Karouri, Salah-Eddine [Institut Cochin, Universite Paris Descartes, CNRS (UMR 8104), Paris (France); Inserm, U567, Paris (France); Issad, Tarik, E-mail: tarik.issad@inserm.fr [Institut Cochin, Universite Paris Descartes, CNRS (UMR 8104), Paris (France); Inserm, U567, Paris (France)

    2009-10-02

    The protein tyrosine phosphatase 1B (PTP1B) and the T-cell protein tyrosine phosphatase (TC-PTP) were initially thought to be mainly anti-oncogenic. However, overexpression of PTP1B and TC-PTP has been observed in human tumors, and recent studies have demonstrated that PTP1B contributes to the appearance of breast tumors by modulating ERK pathway. In the present work, we observed that decreasing the expression of TC-PTP or PTP1B in MCF-7 cells using siRNA reduced cell proliferation without affecting cell death. This reduction in proliferation was associated with decreased ERK phosphorylation. Moreover, selection of tamoxifen-resistant MCF-7 cells, by long-term culture in presence of 4-OH tamoxifen, resulted in cells that display overexpression of PTP1B and TC-PTP, and concomitant increase in ERK and STAT3 phosphorylation. siRNA experiments showed that PTP1B, but not TC-PTP, is necessary for resistance to 4-OH tamoxifen. Therefore, our work indicates that PTP1B could be a relevant therapeutic target for treatment of tamoxifen-resistant breast cancers.

  20. FIN13, a novel growth factor-inducible serine-threonine phosphatase which can inhibit cell cycle progression.

    Guthridge, M A; Bellosta, P; Tavoloni, N; Basilico, C.

    1997-01-01

    We have identified a novel type 2C serine-threonine phosphatase, FIN13, whose expression is induced by fibroblast growth factor 4 and serum in late G1 phase. The protein encoded by FIN13 cDNA includes N- and C-terminal domains with significant homologies to type 2C phosphatases, a domain homologous to collagen, and an acidic domain. FIN13 expression predominates in proliferating tissues. Bacterially expressed FIN13 and FIN13 expressed in mammalian cells exhibit serine-threonine phosphatase ac...

  1. Cervix carcinoma is associated with an up-regulation and nuclear localization of the dual-specificity protein phosphatase VHR

    The 21-kDa Vaccinia virus VH1-related (VHR) dual-specific protein phosphatase (encoded by the DUSP3 gene) plays a critical role in cell cycle progression and is itself regulated during the cell cycle. We have previously demonstrated using RNA interference that cells lacking VHR arrest in the G1 and G2 phases of the cell cycle and show signs of beginning of cell senescence. In this report, we evaluated successfully the expression levels of VHR protein in 62 hysterectomy or conization specimens showing the various (pre) neoplastic cervical epithelial lesions and 35 additional cases of hysterectomy performed for non-cervical pathologies, from patients under 50 years of age. We used a tissue microarray and IHC technique to evaluate the expression of the VHR phosphatase. Immunofluorescence staining under confocal microscopy, Western blotting and RT-PCR methods were used to investigate the localization and expression levels of VHR. We report that VHR is upregulated in (pre) neoplastic lesions (squamous intraepithelial lesions; SILs) of the uterine cervix mainly in high grade SIL (H-SIL) compared to normal exocervix. In the invasive cancer, VHR is also highly expressed with nuclear localization in the majority of cells compared to normal tissue where VHR is always in the cytoplasm. We also report that this phosphatase is highly expressed in several cervix cancer cell lines such as HeLa, SiHa, CaSki, C33 and HT3 compared to primary keratinocytes. The immunofluorescence technique under confocal microscopy shows that VHR has a cytoplasmic localization in primary keratinocytes, while it localizes in both cytoplasm and nucleus of the cancer cell lines investigated. We report that the up-regulation of this phosphatase is mainly due to its post-translational stabilization in the cancer cell lines compared to primary keratinocytes rather than increases in the transcription of DUSP3 locus. These results together suggest that VHR can be considered as a new marker for cancer

  2. Sensitive and direct electrochemical detection of double-stranded DNA utilizing alkaline phosphatase-labelled zinc finger proteins.

    Noh, Soodong; Ha, Dat Thinh; Yang, Haesik; Kim, Moon-Soo

    2015-06-21

    Direct detection of double-stranded DNA (dsDNA) using zinc finger proteins (ZFPs) is of great importance in biomedical applications such as identifying pathogens and circulating DNAs. However, its sensitivity is still not sufficiently high because limited signalling labels can be conjugated or fused. Herein, we report sensitive and direct detection of dsDNA using (i) alkaline phosphatase (ALP) as a fast catalytic label conjugated to ZFPs along with (ii) electrochemical measurement of an ALP product (l-ascorbic acid) at the indium-tin oxide electrode with a high signal-to-background ratio. ALP is simply conjugated to a ZFP through lysine residues in a ZFP purification tag, a maltose binding protein (MBP). Sandwich-type electrochemical detection of dsDNA allows a detection limit of ca. 100 fM without using DNA amplification. PMID:25969923

  3. Phosphorylation of inhibitor-2 and activation of MgATP-dependent protein phosphatase by rat skeletal muscle glycogen synthase kinase

    Rat skeletal muscle contains a glycogen synthase kinase (GSK-M) which is not stimulated by Ca2+ or cAMP. This kinase has an apparent Mr of 62,000 and uses ATP but not GTP as a phosphoryl donor. GSK-M phosphorylated glycogen synthase at sites 2 and 3. It phosphorylated ATP-citrate lyase and activated MgATP-dependent phosphatase in the presence of ATP but not GTP. As expected, the kinase also phosphorylated phosphatase inhibitor 2 (I-2). Phosphatase incorporation reached approximately 0.3 mol/mol of I-2. Phosphopeptide maps were obtained by digesting 32P-labeled I-2 with trypsin and separating the peptides by reversed phase HPLC. Two partially separated 32P-labeled peaks were obtained when I-2 was phosphorylated with either GSK-M or glycogen synthase kinase 3 (GSK-3) and these peptides were different from those obtained when I-2 was phosphorylated with the catalytic subunit of cAMP-dependent protein kinase (CSU) or casein kinase II (CK-II). When I-2 was phosphorylated with GSK-M or GSK-3 and cleaved by CNBr, a single radioactive peak was obtained. Phosphoamino acid analysis showed that I-2 was phosphorylated by GSK-M or GSK-3 predominately in Thr whereas CSU and CK-II phosphorylated I-2 exclusively in Ser. These results indicate that GSK-M is similar to GSK-3 and to ATP-citrate lyase kinase. However, it appears to differ in Mr from ATP-citrate lyase kinase and it differs from GSK-3 in that it phosphorylates glycogen synthase at site 2 and it does not use GTP as a phosphoryl donor

  4. Phosphorylation of inhibitor-2 and activation of MgATP-dependent protein phosphatase by rat skeletal muscle glycogen synthase kinase

    Hegazy, M.G.; Reimann, E.M.; Thysseril, T.J.; Schlender, K.K.

    1986-05-01

    Rat skeletal muscle contains a glycogen synthase kinase (GSK-M) which is not stimulated by Ca/sup 2 +/ or cAMP. This kinase has an apparent Mr of 62,000 and uses ATP but not GTP as a phosphoryl donor. GSK-M phosphorylated glycogen synthase at sites 2 and 3. It phosphorylated ATP-citrate lyase and activated MgATP-dependent phosphatase in the presence of ATP but not GTP. As expected, the kinase also phosphorylated phosphatase inhibitor 2 (I-2). Phosphatase incorporation reached approximately 0.3 mol/mol of I-2. Phosphopeptide maps were obtained by digesting /sup 32/P-labeled I-2 with trypsin and separating the peptides by reversed phase HPLC. Two partially separated /sup 32/P-labeled peaks were obtained when I-2 was phosphorylated with either GSK-M or glycogen synthase kinase 3 (GSK-3) and these peptides were different from those obtained when I-2 was phosphorylated with the catalytic subunit of cAMP-dependent protein kinase (CSU) or casein kinase II (CK-II). When I-2 was phosphorylated with GSK-M or GSK-3 and cleaved by CNBr, a single radioactive peak was obtained. Phosphoamino acid analysis showed that I-2 was phosphorylated by GSK-M or GSK-3 predominately in Thr whereas CSU and CK-II phosphorylated I-2 exclusively in Ser. These results indicate that GSK-M is similar to GSK-3 and to ATP-citrate lyase kinase. However, it appears to differ in Mr from ATP-citrate lyase kinase and it differs from GSK-3 in that it phosphorylates glycogen synthase at site 2 and it does not use GTP as a phosphoryl donor.

  5. Cloning and characterization of R-PTP-kappa, a new member of the receptor protein tyrosine phosphatase family with a proteolytically cleaved cellular adhesion molecule-like extracellular region

    Jiang, Y P; Wang, H; D'Eustachio, P; Musacchio, J M; Schlessinger, J; Sap, J

    1993-01-01

    We describe a new member of the receptor protein tyrosine phosphatase family, R-PTP-kappa, cDNA cloning predicts that R-PTP-kappa is synthesized from a precursor protein of 1,457 amino acids. Its intracellular domain displays the classical tandemly repeated protein tyrosine phosphatase homology, ...

  6. Potential role of lncRNA cyp2c91-protein interactions on diseases of the immune system.

    Suravajhala, Prashanth; Kogelman, Lisette J A; Mazzoni, Gianluca; Kadarmideen, Haja N

    2015-01-01

    With unprecedented increase in next generation sequencing technologies, there has been a persistent interest on transcript profiles of long non-coding RNAs (lncRNAs) and protein-coding genes forming an interaction network. Apart from protein-protein interaction (PPI), gene network models such as Weighted Gene Co-expression Network Analysis (WGCNA) are used to functionally annotate lncRNAs in identifying their potential disease associations. To address this, studies have led to characterizing transcript structures and understanding expression profiles mediating regulatory roles. In the current exploratory analysis, we show how a lncRNA - cyp2c91 contributes to the transcriptional regulation localized to cytoplasm thereby making refractory environment for transcription. By applying network methods and pathway analyses on genes related to a disease such as obesity and systemic lupus erythematosus, we show that we can gain deeper insight in biological processes such as the perturbances in immune system, and get a better understanding of the systems biology of diseases. PMID:26284111

  7. Potential role of lncRNA cyp2c91-protein interactions on diseases of the immune system

    Prashanth eSuravajhala

    2015-07-01

    Full Text Available With unprecedented increase in next generation sequencing (NGS technologies, there has been a persistent interest on transcript profiles of long noncoding RNAs (lncRNAs and protein-coding genes forming an interaction network. Apart from protein-protein interaction (PPI, gene network models such as Weighted Gene Co-expression Network Analysis are used to functionally annotate lncRNAs in identifying their potential disease associations. To address this, studies have led to characterizing transcript structures and understanding expression profiles mediating regulatory roles. In the current exploratory analysis, we show how a lncRNA - cyp2c91 contributes to the transcriptional regulation localized to cytoplasm thereby making refractory environment for transcription. By applying network methods and pathway analyses on genes related to a disease such as obesity and systemic lupus erythematosus, we show that we can gain deeper insight in biological processes such as the perturbances in immune system, and get a better understanding of the systems biology of diseases.

  8. Localization in rat heart mitochondria of outer and inner pools of camp dependent protein kinase, a kinase anchor proteins and PP2C serine phosphatase

    Sardanalli, A. M.; Dobrová, Zuzana; Signorile, A.; Nuzzi, R.; Drahota, Z.; Papa, S.

    Milano, 2003, s. 250. [Join Symposia with the British Biochemical Society /SIP 2003./. Milano (IT), 15.09.2003-18.09.2003] Institutional research plan: CEZ:AV0Z5020903 Keywords : pcamp * akap * aqdq Subject RIV: EE - Microbiology, Virology

  9. Crystal Structure of the Catalytic Domain of a Serine Threonine Protein Phosphatase

    Swinglel, Mark; Honkanel, Richard; Ciszak, Ewa

    2003-01-01

    Reversible phosphorylation of serine and threonine residues is a well-recognized mechanism in eukaryotic cells for the regulation of cell-cycle progression, cell growth and metabolism. Human serine/threonine phosphatases can be placed into two major families, PPP and PPM. To date the structure on one PPP family member (PPl) has been determined. Here we present the structure of a 323-residue catalytic domain of a second phosphatase belonging to the PPP family of enzyme. catalytic domain of the enzyme has been determined to 1.60Angstrom resolution and refined to R=17.5 and Rfree = 20.8%. The catalytic domain possesses a unique fold consisting of a largely monolithic structure, divisible into closely-associated helical and sheet regions. The catalytic site contains two manganese ions that are involved in substrate binding and catalysis. The enzyme crystallizes as a dimer that completely buries catalytic surfaces of both monomers, Also, the structure shows evidence of some flexibility around the active site cleft that may be related to substrate specificity of this enzyme.

  10. cAMP response element binding protein (CREB activates transcription via two distinct genetic elements of the human glucose-6-phosphatase gene

    Stefano Luisa

    2005-01-01

    Full Text Available Abstract Background The enzyme glucose-6-phosphatase catalyzes the dephosphorylation of glucose-6-phosphatase to glucose, the final step in the gluconeogenic and glycogenolytic pathways. Expression of the glucose-6-phosphatase gene is induced by glucocorticoids and elevated levels of intracellular cAMP. The effect of cAMP in regulating glucose-6-phosphatase gene transcription was corroborated by the identification of two genetic motifs CRE1 and CRE2 in the human and murine glucose-6-phosphatase gene promoter that resemble cAMP response elements (CRE. Results The cAMP response element is a point of convergence for many extracellular and intracellular signals, including cAMP, calcium, and neurotrophins. The major CRE binding protein CREB, a member of the basic region leucine zipper (bZIP family of transcription factors, requires phosphorylation to become a biologically active transcriptional activator. Since unphosphorylated CREB is transcriptionally silent simple overexpression studies cannot be performed to test the biological role of CRE-like sequences of the glucose-6-phosphatase gene. The use of a constitutively active CREB2/CREB fusion protein allowed us to uncouple the investigation of target genes of CREB from the variety of signaling pathways that lead to an activation of CREB. Here, we show that this constitutively active CREB2/CREB fusion protein strikingly enhanced reporter gene transcription mediated by either CRE1 or CRE2 derived from the glucose-6-phosphatase gene. Likewise, reporter gene transcription was enhanced following expression of the catalytic subunit of cAMP-dependent protein kinase (PKA in the nucleus of transfected cells. In contrast, activating transcription factor 2 (ATF2, known to compete with CREB for binding to the canonical CRE sequence 5'-TGACGTCA-3', did not transactivate reporter genes containing CRE1, CRE2, or both CREs derived from the glucose-6-phosphatase gene. Conclusions Using a constitutively active CREB2

  11. Electroacupuncture Improves Insulin Resistance by Reducing Neuroprotein Y/Agouti-Related Protein Levels and Inhibiting Expression of Protein Tyrosine Phosphatase 1B in Diet-induced Obese Rats.

    Liu, Xia; He, Jun-Feng; Qu, Ya-Ting; Liu, Zhi-Jun; Pu, Qing-Yang; Guo, Sheng-Tong; Du, Jia; Jiang, Peng-Fei

    2016-04-01

    Electroacupuncture (EA) has been shown to exert beneficial effects on obesity, but the mechanism is unclear. This study investigated the effects of EA on diet-induced obese (DIO) rats. Fifty male Sprague-Dawley rats were randomly divided into low-fat diet (LFD, 10 rats) and high-fat diet (HFD, 40 rats) groups. After the DIO models had been established, successful model rats were randomly divided into HFD, EA, and orlistat (OLST) groups. The EA group received EA at Zusanli (ST36) and Quchi (LI11) for 20 minutes once per day for 28 days. The OLST group was treated with orlistat by gavage. The body weight, homeostasis model assessment-insulin resistance index, adipocyte diameters, and neuroprotein Y/agouti-related protein and protein tyrosine phosphatase 1B levels were significantly lower in the EA group than in the HFD group. The rats of the OLST group showed watery stools and yellow hairs whereas those of the EA group had regular stools and sleek coats. The effect of EA on weight loss may be related to improved insulin resistance caused by changes in the adipocyte size and by reductions in the expressions of neuroprotein Y/agouti-related protein and protein tyrosine phosphatase 1B. This study indicates that EA may be a better method of alternative therapy for treating obesity and other metabolic diseases. PMID:27079226

  12. Cloning and sequence analysis of a full-length cDNA of SmPP1cb encoding turbot protein phosphatase 1 beta catalytic subunit

    Qi, Fei; Guo, Huarong; Wang, Jian

    2008-02-01

    Reversible protein phosphorylation, catalyzed by protein kinases and phosphatases, is an important and versatile mechanism by which eukaryotic cells regulate almost all the signaling processes. Protein phosphatase 1 (PP1) is the first and well-characterized member of the protein serine/threonine phosphatase family. In the present study, a full-length cDNA encoding the beta isoform of the catalytic subunit of protein phosphatase 1(PP1cb), was for the first time isolated and sequenced from the skin tissue of flatfish turbot Scophthalmus maximus, designated SmPP1cb, by the rapid amplification of cDNA ends (RACE) technique. The cDNA sequence of SmPP1cb we obtained contains a 984 bp open reading frame (ORF), flanked by a complete 39 bp 5' untranslated region and 462 bp 3' untranslated region. The ORF encodes a putative 327 amino acid protein, and the N-terminal section of this protein is highly acidic, Met-Ala-Glu-Gly-Glu-Leu-Asp-Val-Asp, a common feature for PP1 catalytic subunit but absent in protein phosphatase 2B (PP2B). And its calculated molecular mass is 37 193 Da and pI 5.8. Sequence analysis indicated that, SmPP1cb is extremely conserved in both amino acid and nucleotide acid levels compared with the PP1cb of other vertebrates and invertebrates, and its Kozak motif contained in the 5'UTR around ATG start codon is GXXAXXGXX ATGG, which is different from mammalian in two positions A-6 and G-3, indicating the possibility of different initiation of translation in turbot, and also the 3'UTR of SmPP1cb is highly diverse in the sequence similarity and length compared with other animals, especially zebrafish. The cloning and sequencing of SmPP1cb gene lays a good foundation for the future work on the biological functions of PP1 in the flatfish turbot.

  13. Taperin (c9orf75, a mutated gene in nonsyndromic deafness, encodes a vertebrate specific, nuclear localized protein phosphatase one alpha (PP1α docking protein

    Tony Ferrar

    2012-02-01

    The promiscuous activity of protein phosphatase one (PP1 is controlled in the cell by associated proteins termed regulatory or targeting subunits. Using biochemical and proteomic approaches we demonstrate that the autosomal recessive nonsyndromic hearing loss gene, taperin (C9orf75, encodes a protein that preferentially docks the alpha isoform of PP1. Taperin associates with PP1 through a classic ‘RVxF’ motif and suppresses the general phosphatase activity of the enzyme. The steady-state localization of taperin is predominantly nuclear, however we demonstrate here that the protein can shuttle between the nucleus and cytoplasm and that it is found complexed to PP1 in both of these cellular compartments. Although originally identified as a hearing loss gene, Western blot analyses with taperin-specific antibodies revealed that the protein is widely expressed across mammalian tissues as multiple splice variants. Taperin is a recent proteome addition appearing during the vertebrate lineage with the PP1 binding site embedded within the most conserved region of the protein. Taperin also shares an ancestral relationship with the cytosolic actin binding protein phostensin, another PP1 interacting partner. Quantitative Stable Isotope Labeling by Amino acids in Culture (SILAC-based mass spectrometry was employed to uncover additional taperin binding partners, and revealed an interaction with the DNA damage response proteins Ku70, Ku80, PARP and topoisomerases I and IIα. Consistent with this, we demonstrate the active recruitment of taperin to sites of DNA damage. This makes taperin a new addition to the family of PP1 targeting subunits involved in the DNA damage repair pathway.

  14. Protein tyrosine phosphatase 1B (PTP1B)-inhibiting constituents from the leaves of Syzygium polyanthum.

    Saifudin, Azis; Tanaka, Ken; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2012-08-01

    A methanol extract of the leaves of Syzygium polyanthum (Wight) Walp. afforded four new acylbenzene derivatives (1-4) together with seven known compounds (5-11). The structures of 1-11 were elucidated by extensive spectroscopic methods and comparison with the literature data. The new compounds 1-3 and a known compound, campest-4-en-3-one (10), exhibited a significant protein tyrosine phosphatase 1B inhibitory activity with IC₅₀ values of 13.1 ± 0.1, 5.77 ± 0.15, 4.01 ± 0.26, and 10.4 ± 0.5 µM, respectively. The inhibitory potency of the new compounds 2 and 3 was comparable to that of a positive control RK-682 (IC₅₀, 5.51 ± 0.04 µM). PMID:22763740

  15. Use of an Anaerobic Chamber Environment for the Assay of Endogenous Cellular Protein-Tyrosine Phosphatase Activities

    Zhu Li

    2002-01-01

    Full Text Available Protein-tyrosine phosphatases (PTPases have a catalytic cysteine residue whose reduced state is integral to the reaction mechanism. Since exposure to air can artifactually oxidize this highly reactive thiol, PTPase assays have typically used potent reducing agents to reactivate the enzymes present; however, this approach does not allow for the measurement of the endogenous PTPase activity directly isolated from the in vivo cellular environment. Here we provide a method for using an anaerobic chamber to preserve the activity of the total PTPase complement in a tissue lysate or of an immunoprecipitated PTPase homolog to characterize their endogenous activation state. Comparison with a sample treated with biochemical reducing agents allows the determination of the activatable (reducible fraction of the endogenous PTPase pool.

  16. Crystallization and preliminary crystallographic analysis of two Streptococcus agalactiae proteins: the family II inorganic pyrophosphatase and the serine/threonine phosphatase

    Two S. agalactiae proteins, the inorganic pyrophosphatase and the serine/threonine phosphatase, were crystallized and diffraction data were collected and processed from these crystals. The data from the two protein crystals extended to 2.80 and 2.65 Å, respectively. Streptococcus agalactiae, which infects human neonates and causes sepsis and meningitis, has recently been shown to possess a eukaryotic-like serine/threonine protein phosphorylation signalling cascade. Through their target proteins, the S. agalactiae Ser/Thr kinase and Ser/Thr phosphatase together control the growth as well as the morphology and virulence of this organism. One of the targets is the S. agalactiae family II inorganic pyrophosphatase. The inorganic pyrophosphatase and the serine/threonine phosphatase have therefore been purified and crystallized and diffraction data have been collected from their crystals. The data were processed using XDS. The inorganic pyrosphosphatase crystals diffracted to 2.80 Å and the Ser/Thr phosphatase crystals to 2.65 Å. Initial structure-solution experiments indicate that structure solution will be successful in both cases. Solving the structure of the proteins involved in this cascade is the first step towards understanding this phenomenon in atomic detail

  17. Crystallization and preliminary crystallographic analysis of two Streptococcus agalactiae proteins: the family II inorganic pyrophosphatase and the serine/threonine phosphatase

    Rantanen, Mika K.; Lehtiö, Lari [Institute of Biotechnology, University of Helsinki, PO Box 65, FIN-00014, Helsinki (Finland); Rajagopal, Lakshmi; Rubens, Craig E. [Division of Infectious Disease, Children’s Hospital and Regional Medical Center, Seattle, Washington 98105 (United States); Goldman, Adrian, E-mail: adrian.goldman@helsinki.fi [Institute of Biotechnology, University of Helsinki, PO Box 65, FIN-00014, Helsinki (Finland)

    2006-09-01

    Two S. agalactiae proteins, the inorganic pyrophosphatase and the serine/threonine phosphatase, were crystallized and diffraction data were collected and processed from these crystals. The data from the two protein crystals extended to 2.80 and 2.65 Å, respectively. Streptococcus agalactiae, which infects human neonates and causes sepsis and meningitis, has recently been shown to possess a eukaryotic-like serine/threonine protein phosphorylation signalling cascade. Through their target proteins, the S. agalactiae Ser/Thr kinase and Ser/Thr phosphatase together control the growth as well as the morphology and virulence of this organism. One of the targets is the S. agalactiae family II inorganic pyrophosphatase. The inorganic pyrophosphatase and the serine/threonine phosphatase have therefore been purified and crystallized and diffraction data have been collected from their crystals. The data were processed using XDS. The inorganic pyrosphosphatase crystals diffracted to 2.80 Å and the Ser/Thr phosphatase crystals to 2.65 Å. Initial structure-solution experiments indicate that structure solution will be successful in both cases. Solving the structure of the proteins involved in this cascade is the first step towards understanding this phenomenon in atomic detail.

  18. Inhibition of receptor tyrosine kinase signalling by small molecule agonist of T-cell protein tyrosine phosphatase

    T-cell protein tyrosine phosphatase (TCPTP/TC45) is a ubiquitously expressed intra-cellular non-receptor protein tyrosine phosphatase involved in the negative regulation of several cancer relevant cellular signalling pathways. We have previously shown that interaction between the α-cytoplasmic tail of α1β1 integrin and TCPTP activates TCPTP by disrupting an inhibitory intra-molecular bond in TCPTP. Thus, inhibition of the regulatory interaction in TCPTP is a desirable strategy for TCPTP activation and attenuation of oncogenic RTK signalling. However, this is challenging with low molecular weight compounds. We developed a high-throughput compatible assay to analyse activity of recombinant TCPTP in vitro. Using this assay we have screened 64280 small molecules to identify novel agonists for TCPTP. Dose-dependent response to TCPTP agonist was performed using the in vitro assay. Inhibition effects and specificity of TCPTP agonists were evaluated using TCPTP expressing and null mouse embryonic fibroblasts. Western blot analysis was used to evaluate attenuation of PDGFRβ and EGFR phosphorylation. Inhibition of VEGF signalling was analysed with VEGF-induced endothelial cell sprouting assays. From the screen we identified six TCPTP agonists. Two compounds competed with α1-cytoplasmic domain for binding to TCPTP, suggesting that they activate TCPTP similar to α1-cyt by disrupting the intra-molecular bond in TCPTP. Importantly, one of the compounds (spermidine) displayed specificity towards TCPTP in cells, since TCPTP -/- cells were 43-fold more resistant to the compound than TCPTP expressing cells. This compound attenuates PDGFRβ and VEGFR2 signalling in cells in a TCPTP-dependent manner and functions as a negative regulator of EGFR phosphorylation in cancer cells. In this study we showed that small molecules mimicking TCPTP-α1 interaction can be used as TCPTP agonists. These data provide the first proof-of-concept description of the use of high-throughput screening

  19. Integrin α1β1 Promotes Caveolin-1 Dephosphorylation by Activating T Cell Protein-tyrosine Phosphatase*

    Borza, Corina M.; Chen, Xiwu; Mathew, Sijo; Mont, Stacey; Sanders, Charles R.; Zent, Roy; Pozzi, Ambra

    2010-01-01

    Integrin α1β1 is a collagen receptor that down-regulates collagen and reactive oxygen species (ROS) production, and mice lacking this receptor show increased ROS levels and exacerbated glomerular sclerosis following injury. Caveolin-1 (Cav-1) is a multifunctional protein that is tyrosine-phosphorylated in response to injury and has been implicated in ROS-mediated injury. Cav-1 interacts with integrins, and integrin α1β1 binds/activates T cell protein-tyrosine phosphatase (TCPTP), which is homologous to the tyrosine phosphatase PTP1B known to dephosphorylate Cav-1. In this study, we analyzed whether phosphorylated Cav-1 (pCav-1) is a substrate of TCPTP and if integrin α1β1 is essential for promoting TCPTP-mediated Cav-1 dephosphorylation. We found that Cav-1 phosphorylation is significantly higher in cells lacking integrin α1β1 at base line and following oxidative stress. Overexpression of TCPTP leads to reduced pCav-1 levels only in cells expressing integrin α1β1. Using solid phase binding assays, we demonstrated that 1) purified Cav-1 directly interacts with TCPTP and the integrin α1 subunit, 2) pCav-1 is a substrate of TCPTP, and 3) TCPTP-mediated Cav-1 dephosphorylation is highly increased by the addition of purified integrin α1β1 or an integrin α1 cytoplasmic peptide to which TCPTP has been shown to bind. Thus, our results demonstrate that pCav-1 is a new substrate of TCPTP and that integrin α1β1 acts as a negative regulator of Cav-1 phosphorylation by activating TCPTP. This could explain the protective function of integrin α1β1 in oxidative stress-mediated damage and why integrin α1-null mice are more susceptible to fibrosis following injury. PMID:20940300

  20. Integrin {alpha}1{beta}1 promotes caveolin-1 dephosphorylation by activating T cell protein-tyrosine phosphatase.

    Borza, Corina M; Chen, Xiwu; Mathew, Sijo; Mont, Stacey; Sanders, Charles R; Zent, Roy; Pozzi, Ambra

    2010-12-17

    Integrin α1β1 is a collagen receptor that down-regulates collagen and reactive oxygen species (ROS) production, and mice lacking this receptor show increased ROS levels and exacerbated glomerular sclerosis following injury. Caveolin-1 (Cav-1) is a multifunctional protein that is tyrosine-phosphorylated in response to injury and has been implicated in ROS-mediated injury. Cav-1 interacts with integrins, and integrin α1β1 binds/activates T cell protein-tyrosine phosphatase (TCPTP), which is homologous to the tyrosine phosphatase PTP1B known to dephosphorylate Cav-1. In this study, we analyzed whether phosphorylated Cav-1 (pCav-1) is a substrate of TCPTP and if integrin α1β1 is essential for promoting TCPTP-mediated Cav-1 dephosphorylation. We found that Cav-1 phosphorylation is significantly higher in cells lacking integrin α1β1 at base line and following oxidative stress. Overexpression of TCPTP leads to reduced pCav-1 levels only in cells expressing integrin α1β1. Using solid phase binding assays, we demonstrated that 1) purified Cav-1 directly interacts with TCPTP and the integrin α1 subunit, 2) pCav-1 is a substrate of TCPTP, and 3) TCPTP-mediated Cav-1 dephosphorylation is highly increased by the addition of purified integrin α1β1 or an integrin α1 cytoplasmic peptide to which TCPTP has been shown to bind. Thus, our results demonstrate that pCav-1 is a new substrate of TCPTP and that integrin α1β1 acts as a negative regulator of Cav-1 phosphorylation by activating TCPTP. This could explain the protective function of integrin α1β1 in oxidative stress-mediated damage and why integrin α1-null mice are more susceptible to fibrosis following injury. PMID:20940300

  1. Diversity in genomic organisation, developmental regulation and distribution of the murine PR72/B" subunits of protein phosphatase 2A

    Janssens Veerle

    2008-08-01

    Full Text Available Abstract Background Protein phosphatase 2A (PP2A is a serine/threonine-specific phosphatase displaying vital functions in growth and development through its role in various signalling pathways. PP2A holoenzymes comprise a core dimer composed of a catalytic C and a structural A subunit, which can associate with a variable B-type subunit. The importance of the B-type subunits for PP2A regulation cannot be overestimated as they determine holoenzyme localisation, activity and substrate specificity. Three B-type subunit families have been identified: PR55/B, PR61/B' and PR72/B", of which the latter is currently the least characterised. Results We deduced the sequences and genomic organisation of the different murine PR72/B" isoforms: three genes encode nine isoforms, five of which are abundantly expressed and give rise to genuine PP2A subunits. Thereby, one novel subunit was identified. Using Northern blotting, we examined the tissue-specific and developmental expression of these subunits. All subunits are highly expressed in heart, suggesting an important cardiac function. Immunohistochemical analysis revealed a striated expression pattern of PR72 and PR130 in heart and skeletal muscle, but not in bladder smooth muscle. The subcellular localisation and cell cycle regulatory ability of several PR72/B" isoforms were determined, demonstrating differences as well as similarities. Conclusion In contrast to PR55/B and PR61/B', the PR72/B" family seems evolutionary more divergent, as only two of the murine genes have a human orthologue. We have integrated these results in a more consistent nomenclature of both human and murine PR72/B" genes and their transcripts/proteins. Our results provide a platform for the future generation of PR72/B" knockout mice.

  2. Overexpression of protein tyrosine phosphatase-alpha (PTP-alpha) but not PTP-kappa inhibits translocation of GLUT4 in rat adipose cells

    Cong, L N; Chen, H; Li, Y;

    1999-01-01

    Protein tyrosine phosphatases (PTPases) are likely to play important roles in insulin action. We recently demonstrated that the nontransmembrane PTPase PTP1B can act as a negative modulator of insulin-stimulated translocation of GLUT4. We now examine the role of PTP-alpha and PTP-kappa (two trans......-stimulated glucose transport....

  3. Protein tyrosine phosphatase PTPN14 is a regulator of lymphatic function and choanal development in humans.

    Au, Audrey C; Hernandez, Paolo A; Lieber, Ernest; Nadroo, Ali M; Shen, Yu-Ming; Kelley, Kevin A; Gelb, Bruce D; Diaz, George A

    2010-09-10

    The lymphatic vasculature is essential for the recirculation of extracellular fluid, fat absorption, and immune function and as a route of tumor metastasis. The dissection of molecular mechanisms underlying lymphangiogenesis has been accelerated by the identification of tissue-specific lymphatic endothelial markers and the study of congenital lymphedema syndromes. We report the results of genetic analyses of a kindred inheriting a unique autosomal-recessive lymphedema-choanal atresia syndrome. These studies establish linkage of the trait to chromosome 1q32-q41 and identify a loss-of-function mutation in PTPN14, which encodes a nonreceptor tyrosine phosphatase. The causal role of PTPN14 deficiency was confirmed by the generation of a murine Ptpn14 gene trap model that manifested lymphatic hyperplasia with lymphedema. Biochemical studies revealed a potential interaction between PTPN14 and the vascular endothelial growth factor receptor 3 (VEGFR3), a receptor tyrosine kinase essential for lymphangiogenesis. These results suggest a unique and conserved role for PTPN14 in the regulation of lymphatic development in mammals and a nonconserved role in choanal development in humans. PMID:20826270

  4. Receptor-type Protein Tyrosine Phosphatase β Regulates Met Phosphorylation and Function in Head and Neck Squamous Cell Carcinoma

    Yiru Xu

    2012-11-01

    Full Text Available Head and neck squamous cell carcinoma (HNSCC is the sixth most common cancer and has a high rate of mortality. Emerging evidence indicates that hepatocyte growth factor receptor (or Met pathway plays a pivotal role in HNSCC metastasis and resistance to chemotherapy. Met function is dependent on tyrosine phosphorylation that is under direct control by receptor-type protein tyrosine phosphatase β (RPTP-β. We report here that RPTP-β expression is significantly downregulated in HNSCC cells derived from metastatic tumors compared to subject-matched cells from primary tumors. Knockdown of endogenous RPTP-β in HNSCC cells from primary tumor potentiated Met tyrosine phosphorylation, downstream mitogen-activated protein (MAP kinase pathway activation, cell migration, and invasion. Conversely, restoration of RPTP-β expression in cells from matched metastatic tumor decreased Met tyrosine phosphorylation and downstream functions. Furthermore, we observed that six of eight HNSCC tumors had reduced levels of RPTP-β protein in comparison with normal oral tissues. Collectively, the results demonstrate the importance of RPTP-β in tumor biology of HNSCC through direct dephosphorylation of Met and regulation of downstream signal transduction pathways. Reduced RPTP-β levels, with or without Met overexpression, could promote Met activation in HNSCC tumors.

  5. Light-switched inhibitors of protein tyrosine phosphatase PTP1B based on phosphonocarbonyl phenylalanine as photoactive phosphotyrosine mimetic.

    Wagner, Stefan; Schütz, Anja; Rademann, Jörg

    2015-06-15

    Phosphopeptide mimetics containing the 4-phosphonocarbonyl phenylalanine (pcF) as a photo-active phosphotyrosine isoster are developed as potent, light-switchable inhibitors of the protein tyrosine phosphatase PTP1B. The photo-active inhibitors 6-10 are derived from phosphopeptide substrates and are prepared from the suitably protected pcF building block 12 by Fmoc-based solid phase peptide synthesis. All pcF-containing peptides are moderate inhibitors of PTP1B with KI values between 10 and 50μM. Irradiation of the inhibitors at 365nm in the presence of the protein PTP1B amplify the inhibitory activity of pcF-peptides up to 120-fold, switching the KI values of the best inhibitors to the sub-micromolar range. Photo-activation of the inhibitors results in the formation of triplet intermediates of the benzoylphosphonate moiety, which deactivate PTP1B following an oxidative radical mechanism. Deactivation of PTP1B proceeds without covalent crosslinking of the protein target with the photo-switched inhibitors and can be reverted by subsequent addition of reducing agent dithiothreitol (DTT). PMID:25907367

  6. Identification of protein tyrosine phosphatase 1B and casein as substrates for 124-v-Mos

    Stabel Silvia; Proikas-Cezanne Tassula; Riethmacher Dieter

    2002-01-01

    Abstract Background The mos proto-oncogene encodes a cytoplasmic serine/threonine-specific protein kinase with crucial function during meiotic cell division in vertebrates. Based on oncogenic amino acid substitutions the viral derivative, 124-v-Mos, displays constitutive protein kinase activity and functions independent of unknown upstream effectors of mos protein kinase. We have utilized this property of 124-v-Mos and screened for novel mos substrates in immunocomplex kinase assays in vitro....

  7. Knockdown of microRNA-195 contributes to protein phosphatase-2A inactivation in rats with chronic brain hypoperfusion.

    Liu, Cheng-Di; Wang, Qin; Zong, De-Kang; Pei, Shuang-Chao; Yan, Yan; Yan, Mei-Ling; Sun, Lin-Lin; Hao, Yang-Yang; Mao, Meng; Xing, Wen-Jing; Ren, Huan; Ai, Jing

    2016-09-01

    Reduction of protein phosphatase-2A (PP2A) activity is a common clinical feature of Alzheimer's disease and vascular dementia. In this study, we observed that chronic brain hypoperfusion induced by bilateral common carotid artery occlusion of rats led to PP2A inactivation based on the increase in tyrosine-307 phosphorylation and leucine-309 demethylation of PP2AC and the depression in PP2ABα. Knockdown of miR-195 using overexpression of its antisense molecule oligonucleotide (pre-AMO-miR-195) delivered by a lentivirus (lenti-pre-AMO-miR-195) increased tyrosine-307 phosphorylation and decreased both PP2ABα expression and leucine-309 methylation; these effects were prevented by the overexpression of miR-195 using lenti-pre-miR-195 and controlled by an increase in methylesterase (PME-1) and a decrease in leucine carboxyl methyltransferase-1. In vitro studies demonstrated that miR-195 regulated PME-1 expression by binding to the Ppme1 gene 3'-untranslated region (3'UTR) domain. Masking the miR-195 binding sites in the amyloid precursor protein (APP) and β-site APP cleaving enzyme 1 genes prevented miR-195-induced leucine carboxyl methyltransferase-1 elevation. We concluded that the miR-195 downregulation in chronic brain hypoperfusion involved PP2A inactivity, which was mediated by the post-transcriptional regulation PME-1, APP, and β-site APP cleaving enzyme 1 expression. PMID:27459928

  8. Effect of microcystin-LR on protein phosphatase 2A and its function in human amniotic epithelial cells

    Jing LIANG; Tan LI; Ya-li ZHANG; Zong-lou GUO; Li-hong XU

    2011-01-01

    Due to their toxicity,the increased distribution of microcystins (MCs) has become an important worldwide problem.MCs have been recognized as inhibitors of protein phosphatase 2A (PP2A) through their binding to the PP2A catalytic subunit.However,the exact mechanism of MC toxicity has not been elucidated,especially concerning the cellular response and its autoregulation.To further dissect the role of PP2A in MC-induced toxicity,the present study was undertaken to determine the response of PP2A in human amniotic epithelial (FL) cells treated with microcystin-LR (MCLR),one of the MC congeners.The results show that a low-dose treatment of MCLR in FL cells for 6 h induced an increase in PP2A activity,and a high-dose treatment of MCLR for 24 h decreased the activity of PP2A,as expected.The increased mRNA and protein levels of the PP2A C subunit may explain the increased activity of PP2A.Furthermore,MCLR altered microtubule post-translational modifications through PP2A.These results further clarify the underlying mechanism how MCLR affects PP2A and may be helpful for elucidating the complex toxicity of MCLR.

  9. Hypothermic Preconditioning Reverses Tau Ontogenesis in Human Cortical Neurons and is Mimicked by Protein Phosphatase 2A Inhibition.

    Rzechorzek, Nina M; Connick, Peter; Livesey, Matthew R; Borooah, Shyamanga; Patani, Rickie; Burr, Karen; Story, David; Wyllie, David J A; Hardingham, Giles E; Chandran, Siddharthan

    2016-01-01

    Hypothermia is potently neuroprotective, but the molecular basis of this effect remains obscure. Changes in neuronal tau protein are of interest, since tau becomes hyperphosphorylated in injury-resistant, hypothermic brains. Noting inter-species differences in tau isoforms, we have used functional cortical neurons differentiated from human pluripotent stem cells (hCNs) to interrogate tau modulation during hypothermic preconditioning at clinically-relevant temperatures. Key tau developmental transitions (phosphorylation status and splicing shift) are recapitulated during hCN differentiation and subsequently reversed by mild (32 °C) to moderate (28 °C) cooling--conditions which reduce oxidative and excitotoxic stress-mediated injury in hCNs. Blocking a major tau kinase decreases hCN tau phosphorylation and abrogates hypothermic neuroprotection, whilst inhibition of protein phosphatase 2A mimics cooling-induced tau hyperphosphorylation and protects normothermic hCNs from oxidative stress. These findings indicate a possible role for phospho-tau in hypothermic preconditioning, and suggest that cooling drives human tau towards an earlier ontogenic phenotype whilst increasing neuronal resilience to common neurotoxic insults. This work provides a critical step forward in understanding how we might exploit the neuroprotective benefits of cooling without cooling patients. PMID:26870825

  10. Avicin D: a protein reactive plant isoprenoid dephosphorylates Stat 3 by regulating both kinase and phosphatase activities.

    Valsala Haridas

    Full Text Available Avicins, a class of electrophilic triterpenoids with pro-apoptotic, anti-inflammatory and antioxidant properties, have been shown to induce redox-dependant post-translational modification of cysteine residues to regulate protein function. Based on (a the cross-talk that occurs between redox and phosphorylation processes, and (b the role of Stat3 in the process of apoptosis and carcinogenesis, we chose to study the effects of avicins on the processes of phosphorylation/dephosphorylation in Stat3. Avicins dephosphorylate Stat3 in a variety of human tumor cell lines, leading to a decrease in the transcriptional activity of Stat3. The expression of Stat3-regulated proteins such as c-myc, cyclin D1, Bcl2, survivin and VEGF were reduced in response to avicin treatment. Underlying avicin-induced dephosphorylation of Stat3 was dephosphorylation of JAKs, as well as activation of protein phosphatase-1. Downregulation of both Stat3 activity and expression of Stat 3-controlled pro-survival proteins, contributes to the induction of apoptosis in avicin treated tumor cells. Based on the role of Stat3 in inflammation and wounding, and the in vivo inhibition of VEGF by avicins in a mouse skin carcinogenesis model, it is likely that avicin-induced inhibition of Stat3 activity results in the suppression of the pro-inflammatory and pro-oxidant stromal environment of tumors. Activation of PP-1, which also acts as a cellular economizer, combined with the redox regulation by avicins, can aid in redirecting metabolism from growth promoting anabolic to energy sparing pathways.

  11. Inhibition of receptor tyrosine kinase signalling by small molecule agonist of T-cell protein tyrosine phosphatase

    Tähtinen Siri

    2010-01-01

    Full Text Available Abstract Background T-cell protein tyrosine phosphatase (TCPTP/TC45 is a ubiquitously expressed intra-cellular non-receptor protein tyrosine phosphatase involved in the negative regulation of several cancer relevant cellular signalling pathways. We have previously shown that interaction between the α-cytoplasmic tail of α1β1 integrin and TCPTP activates TCPTP by disrupting an inhibitory intra-molecular bond in TCPTP. Thus, inhibition of the regulatory interaction in TCPTP is a desirable strategy for TCPTP activation and attenuation of oncogenic RTK signalling. However, this is challenging with low molecular weight compounds. Methods We developed a high-throughput compatible assay to analyse activity of recombinant TCPTP in vitro. Using this assay we have screened 64280 small molecules to identify novel agonists for TCPTP. Dose-dependent response to TCPTP agonist was performed using the in vitro assay. Inhibition effects and specificity of TCPTP agonists were evaluated using TCPTP expressing and null mouse embryonic fibroblasts. Western blot analysis was used to evaluate attenuation of PDGFRβ and EGFR phosphorylation. Inhibition of VEGF signalling was analysed with VEGF-induced endothelial cell sprouting assays. Results From the screen we identified six TCPTP agonists. Two compounds competed with α1-cytoplasmic domain for binding to TCPTP, suggesting that they activate TCPTP similar to α1-cyt by disrupting the intra-molecular bond in TCPTP. Importantly, one of the compounds (spermidine displayed specificity towards TCPTP in cells, since TCPTP -/- cells were 43-fold more resistant to the compound than TCPTP expressing cells. This compound attenuates PDGFRβ and VEGFR2 signalling in cells in a TCPTP-dependent manner and functions as a negative regulator of EGFR phosphorylation in cancer cells. Conclusions In this study we showed that small molecules mimicking TCPTP-α1 interaction can be used as TCPTP agonists. These data provide the first

  12. Identification of Plasmodium falciparum Translation Initiation eIF2β Subunit: Direct Interaction with Protein Phosphatase Type 1

    Tellier, Géraldine; Lenne, Astrid; Cailliau-Maggio, Katia; Cabezas-Cruz, Alejandro; Valdés, James J.; Martoriati, Alain; Aliouat, El M.; Gosset, Pierre; Delaire, Baptiste; Fréville, Aline; Pierrot, Christine; Khalife, Jamal

    2016-01-01

    Protein phosphatase 1 (PP1c) is one of the main phosphatases whose function is shaped by many regulators to confer a specific location and a selective function for this enzyme. Here, we report that eukaryotic initiation factor 2β of Plasmodium falciparum (PfeIF2β) is an interactor of PfPP1c. Sequence analysis of PfeIF2β revealed a deletion of 111 amino acids when compared to its human counterpart and the presence of two potential binding motifs to PfPP1 (29FGEKKK34, 103KVAW106). As expected, we showed that PfeIF2β binds PfeIF2γ and PfeIF5, confirming its canonical interaction with partners of the translation complex. Studies of the PfeIF2β-PfPP1 interaction using wild-type, single and double mutated versions of PfeIF2β revealed that both binding motifs are critical. We next showed that PfeIF2β is able to induce Germinal Vesicle Break Down (GVBD) when expressed in Xenopus oocytes, an indicator of its capacity to regulate PP1. Only combined mutations of both binding motifs abolished the interaction with PP1 and the induction of GVBD. In P. falciparum, although the locus is accessible for genetic manipulation, PfeIF2β seems to play an essential role in intraerythrocytic cycle as no viable knockout parasites were detectable. Interestingly, as for PfPP1, the subcellular fractionation of P. falciparum localized PfeIF2β in cytoplasm and nuclear extracts, suggesting a potential effect on PfPP1 in both compartments and raising the question of a non-canonical function of PfeIf2β in the nucleus. Hence, the role played by PfeIF2β in blood stage parasites could occur at multiple levels involving the binding to proteins of the translational complex and to PfPP1. PMID:27303372

  13. Phosphorus compounds, proteins, nuclease and acid phosphatase activities in isolated spinach chloroplasts

    E. Mikulska

    2015-05-01

    Full Text Available This paper deals with attempts to elaborate a simple method of spinach chloroplast isolation ensuring a high proportion of intact chloroplasts. We obtained 3 preparations of isolated chloroplasts. Several preliminary analyses of the obtained chloroplast fraction were also performed. Phosphorus compounds, total protein and the enzyme activities of RNase, DNase and GPase were determined. We found: 0,36-0,59% of RNA, 0,19-0,24% of DNA, 2,1-2,9% of phospholipids and 26-28% of protein. RNase activity was very high.

  14. The Putative Protein Phosphatase MoYvh1 Functions Upstream of MoPdeH to Regulate the Development and Pathogenicity in Magnaporthe oryzae.

    Liu, Xinyu; Qian, Bin; Gao, Chuyun; Huang, Shuohan; Cai, Yongchao; Zhang, Haifeng; Zheng, Xiaobo; Wang, Ping; Zhang, Zhengguang

    2016-06-01

    Protein phosphatases are critical regulators in eukaryotic cells. For example, the budding yeast Saccharomyces cerevisiae dual specificity protein phosphatase (DSP) ScYvh1 regulates growth, sporulation, and glycogen accumulation. Despite such importance, functions of Yvh1 proteins in filamentous fungi are not well understood. In this study, we characterized putative protein phosphatase MoYvh1, an Yvh1 homolog in the rice blast fungus Magnaporthe oryzae. Deletion of the MoYVH1 gene resulted in significant reductions in vegetative growth, conidial production, and virulence. The ΔMoyvh1 mutant also displayed defects in cell-wall integrity and was hyposensitive to the exogenous osmotic stress. Further examination revealed that the ΔMoyvh1 mutant had defects in appressorium function and invasive hyphae growth, resulting attenuated pathogenicity. Interestingly, we found that MoYvh1 affects the scavenging of host-derived reactive oxygen species that promotes M. oryzae infection. Finally, overexpression of the phosphodiesterase MoPDEH suppressed the defects in conidia formation and pathogenicity of the ΔMoyvh1 mutant, suggesting MoYvh1 could regulate MoPDEH for its function. Our study reveals not only the importance of MoYvh1 proteins in growth, differentiation, and virulence of the rice blast fungus but, also, a genetic link between MoYvh1 and MoPDEH-cAMP signaling in this fungus. PMID:27110741

  15. Cloning of a human insulin-stimulated protein kinase (ISPK-1) gene and analysis of coding regions and mRNA levels of the ISPK-1 and the protein phosphatase-1 genes in muscle from NIDDM patients

    Bjørbaek, C; Vik, T A; Echwald, S M;

    1995-01-01

    Complementary DNA encoding three catalytic subunits of protein phosphatase 1 (PP1 alpha, PP1 beta, and PP1 gamma) and the insulin-stimulated protein kinase 1 (ISPK-1) was analyzed for variations in the coding regions related to insulin-resistant glycogen synthesis in skeletal muscle of 30 patient...

  16. The receptor protein tyrosine phosphatase (RPTP)β/ζ is expressed in different subtypes of human breast cancer

    Increasing evidence suggests mutations in human breast cancer cells that induce inappropriate expression of the 18-kDa cytokine pleiotrophin (PTN, Ptn) initiate progression of breast cancers to a more malignant phenotype. Pleiotrophin signals through inactivating its receptor, the receptor protein tyrosine phosphatase (RPTP)β/ζ, leading to increased tyrosine phosphorylation of different substrate proteins of RPTPβ/ζ, including β-catenin, β-adducin, Fyn, GIT1/Cat-1, and P190RhoGAP. PTN signaling thus has wide impact on different important cellular systems. Recently, PTN was found to activate anaplastic lymphoma kinase (ALK) through the PTN/RPTPβ/ζ signaling pathway; this discovery potentially is very important, since constitutive ALK activity of nucleophosmin (NPM)-ALK fusion protein is causative of anaplastic large cell lymphomas, and, activated ALK is found in other malignant cancers. Recently ALK was identified in each of 63 human breast cancers from 22 subjects. We now demonstrate that RPTPβ/ζ is expressed in each of these same 63 human breast cancers that previously were found to express ALK and in 10 additional samples of human breast cancer. RPTPβ/ζ furthermore was localized not only in its normal association with the cell membrane but also scattered in cytoplasm and in nuclei in different breast cancer cells and, in the case of infiltrating ductal carcinomas, the distribution of RPTPβ/ζ changes as the breast cancer become more malignant. The data suggest that the PTN/RPTPβ/ζ signaling pathway may be constitutively activated and potentially function to constitutively activate ALK in human breast cancer

  17. Mitogen-activated protein kinase phosphatase is required for genotoxic stress relief in Arabidopsis

    Ulm, Roman; Revenkova, Ekaterina; Di Sansebastiano, Gian-Pietro; Bechtold, Nicole; Paszkowski, Jerzy

    2001-01-01

    Genotoxic stress activates complex cellular responses allowing for the repair of DNA damage and proper cell recovery. Although plants are exposed constantly to increasing solar UV irradiation, the signaling cascades activated by genotoxic environments are largely unknown. We have identified an Arabidopsis mutant (mkp1) hypersensitive to genotoxic stress treatments (UV-C and methyl methanesulphonate) due to disruption of a gene that encodes an Arabidopsis homolog of mitogen-activated protein k...

  18. Slitrks control excitatory and inhibitory synapse formation with LAR receptor protein tyrosine phosphatases

    Yim, Yeong Shin; Kwon, Younghee; Nam, Jungyong; Yoon, Hong In; Lee, Kangduk; Kim, Dong Goo; Kim, Eunjoon; Kim, Chul Hoon; Ko, Jaewon

    2013-01-01

    The balance between excitatory and inhibitory synaptic inputs, which is governed by multiple synapse organizers, controls neural circuit functions and behaviors. Slit- and Trk-like proteins (Slitrks) are a family of synapse organizers, whose emerging synaptic roles are incompletely understood. Here, we report that Slitrks are enriched in postsynaptic densities in rat brains. Overexpression of Slitrks promoted synapse formation, whereas RNAi-mediated knockdown of Slitrks decreased synapse dens...

  19. Adiponectin Increases Skeletal Muscle Mitochondrial Biogenesis by Suppressing Mitogen-Activated Protein Kinase Phosphatase-1

    Qiao, Liping; Kinney, Brice; Yoo, Hyung sun; Lee, Bonggi; Schaack, Jerome; Shao, Jianhua

    2012-01-01

    Adiponectin enhances mitochondrial biogenesis and oxidative metabolism in skeletal muscle. This study aimed to investigate the underlying mechanisms through which adiponectin induces mitochondrial biogenesis in skeletal muscle. Mitochondrial contents, expression, and activation status of p38 mitogen-activated protein kinase (MAPK) and PPARγ coactivator 1α (PGC-1α) were compared between skeletal muscle samples from adiponectin gene knockout, adiponectin-reconstituted, and control mice. Adenovi...

  20. DHA Inhibits Protein Degradation More Efficiently than EPA by Regulating the PPARγ/NFκB Pathway in C2C12 Myotubes

    Yue Wang; Qiao-wei Lin; Pei-pei Zheng; Jian-song Zhang; Fei-ruo Huang

    2013-01-01

    This study was conducted to evaluate the mechanism by which n-3 PUFA regulated the protein degradation in C2C12 myotubes. Compared with the BSA control, EPA at concentrations from 400 to 600 µM decreased total protein degradation (P < 0.01). However, the total protein degradation was decreased when the concentrations of DHA ranged from 300 µM to 700 µM (P < 0.01). DHA (400 µM, 24 h) more efficiently decreased the I κ B α phosphorylation and increased in the I κ B α protein level than 400 µM E...

  1. A complex between contactin-1 and the protein tyrosine phosphatase PTPRZ controls the development of oligodendrocyte precursor cells

    Lamprianou, Smaragda; Chatzopoulou, Elli; Thomas, Jean-Léon; Bouyain, Samuel; Harroch, Sheila (IP-Korea); (UPMC); (UMKC)

    2013-09-23

    The six members of the contactin (CNTN) family of neural cell adhesion molecules are involved in the formation and maintenance of the central nervous system (CNS) and have been linked to mental retardation and neuropsychiatric disorders such as autism. Five of the six CNTNs bind to the homologous receptor protein tyrosine phosphatases gamma (PTPRG) and zeta (PTPRZ), but the biological roles of these interactions remain unclear. We report here the cocrystal structure of the carbonic anhydrase-like domain of PTPRZ bound to tandem Ig repeats of CNTN1 and combine these structural data with binding assays to show that PTPRZ binds specifically to CNTN1 expressed at the surface of oligodendrocyte precursor cells. Furthermore, analyses of glial cell populations in wild-type and PTPRZ-deficient mice show that the binding of PTPRZ to CNTN1 expressed at the surface of oligodendrocyte precursor cells inhibits their proliferation and promotes their development into mature oligodendrocytes. Overall, these results implicate the PTPRZ/CNTN1 complex as a previously unknown modulator of oligodendrogenesis.

  2. Synthesis and protein tyrosine phosphatase 1B inhibition activities of two new synthetic bromophenols and their methoxy derivatives

    Cui, Yongchao; Shi, Dayong; Hu, Zhiqiang

    2011-11-01

    3-bromo-4,5-bis(2,3-dibromo-4,5-dihydroxybenzyl)-1,2-benzenediol ( 1) is a natural bromophenol isolated from the red algae Rhodomela confervoides that exhibits significant inhibition against protein tyrosine phosphatase 1B (PTP1B). Based on its activity, we synthesized two new synthetic bromophenols and their methoxy derivatives from vanillin using the structure of natural bromophenol 1 as a scaffold. The structures of these bromophenols were elucidated from 1H NMR, 13C NMR, and high resolution electron ionization mass spectrometry as 2,3-dibromo-1-(2'-bromo-6'-(3″,4″-dimethoxybenzyl)-3',4'-dimethoxybenzyl)-4,5-dimethoxybenzene ( 2), 2,3-dibromo-1-(2'-bromo-6'-(2″-bromo-4″,5″-dimethoxybenzyl)-3',4'-dimethoxybenzyl)-4,5-dimethoxybenzene ( 3), 3,4-dibromo-5-(2'-bromo-6'-(2″-bromo-4″,5″-dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol ( 4) and 3,4-dibromo-5-(2'-bromo-6'-(3″,4″-dihydroxybenzyl)-3',4'-dihydroxybenzyl)pyrocatechol ( 5). PTP1B inhibition activities of these compounds were evaluated using a colorimetric assay, and compounds 3 and 4 demonstrated interesting activity against PTP1B.

  3. The mitogen-activated protein kinase (MAPK) cascade controls phosphatase and tensin homolog (PTEN) expression through multiple mechanisms.

    Ciuffreda, Ludovica; Di Sanza, Cristina; Cesta Incani, Ursula; Eramo, Adriana; Desideri, Marianna; Biagioni, Francesca; Passeri, Daniela; Falcone, Italia; Sette, Giovanni; Bergamo, Paola; Anichini, Andrea; Sabapathy, Kanaga; McCubrey, James A; Ricciardi, Maria Rosaria; Tafuri, Agostino; Blandino, Giovanni; Orlandi, Augusto; De Maria, Ruggero; Cognetti, Francesco; Del Bufalo, Donatella; Milella, Michele

    2012-06-01

    The mitogen-activated protein kinase (MAPK) and PI3K pathways are regulated by extensive crosstalk, occurring at different levels. In tumors, transactivation of the alternate pathway is a frequent "escape" mechanism, suggesting that combined inhibition of both pathways may achieve synergistic antitumor activity. Here we show that, in the M14 melanoma model, simultaneous inhibition of both MEK and mammalian target of rapamycin (mTOR) achieves synergistic effects at suboptimal concentrations, but becomes frankly antagonistic in the presence of relatively high concentrations of MEK inhibitors. This observation led to the identification of a novel crosstalk mechanism, by which either pharmacologic or genetic inhibition of constitutive MEK signaling restores phosphatase and tensin homolog (PTEN) expression, both in vitro and in vivo, and inhibits downstream signaling through AKT and mTOR, thus bypassing the need for double pathway blockade. This appears to be a general regulatory mechanism and is mediated by multiple mechanisms, such as MAPK-dependent c-Jun and miR-25 regulation. Finally, PTEN upregulation appears to be a major effector of MEK inhibitors' antitumor activity, as cancer cells in which PTEN is inactivated are consistently more resistant to the growth inhibitory and anti-angiogenic effects of MEK blockade. PMID:22215152

  4. A rapid lateral flow immunoassay for the detection of tyrosine phosphatase-like protein IA-2 autoantibodies in human serum.

    Ingrid Kikkas

    Full Text Available Type 1 diabetes (T1D results from the destruction of pancreatic insulin-producing beta cells and is strongly associated with the presence of islet autoantibodies. Autoantibodies to tyrosine phosphatase-like protein IA-2 (IA-2As are considered to be highly predictive markers of T1D. We developed a novel lateral flow immunoassay (LFIA based on a bridging format for the rapid detection of IA-2As in human serum samples. In this assay, one site of the IA-2As is bound to HA-tagged-IA-2, which is subsequently captured on the anti-HA-Tag antibody-coated test line on the strip. The other site of the IA-2As is bound to biotinylated IA-2, allowing the complex to be visualized using colloidal gold nanoparticle-conjugated streptavidin. For this study, 35 serum samples from T1D patients and 44 control sera from non-diabetic individuals were analyzed with our novel assay and the results were correlated with two IA-2A ELISAs. Among the 35 serum samples from T1D patients, the IA-2A LFIA, the in-house IA-2A ELISA and the commercial IA-2A ELISA identified as positive 21, 29 and 30 IA-2A-positive sera, respectively. The major advantages of the IA-2A LFIA are its rapidity and simplicity.

  5. Phosphatase Activity of Microbial Populations in Different Milk Samples in Relation to Protein and Carbohydrate Content

    Sosanka Protim SANDILYA; Anuradha GOGOI; Pinky Moni BHUYAN; Dip Kumar GOGOI

    2014-01-01

    Cattle milk is a rich source of protein, carbohydrate, vitamins, minerals and all other major and micro nutrients. At a moderate pH, milk is an excellent media for the growth of microbes and thus, intake of raw milk is precarious. In this study, attempt was made for a qualitative study of eight raw milk samples of different varieties of cow and goat milk, collected from Jorhat district of Assam, India, on the basis of nutritional value and microbial population. The highest microbial populatio...

  6. Nuclear localization of CPI-17, a protein phosphatase-1 inhibitor protein, affects histone H3 phosphorylation and corresponds to proliferation of cancer and smooth muscle cells

    Highlights: •Non-canonical roles of the myosin phosphatase inhibitor (CPI-17) were studied. •CPI-17 is localized in the nucleus of hyperplastic cancer and smooth muscle cells. •CPI-17 Ser12 phosphorylation may regulate the nuclear import. •CPI-17 regulates histone H3 phosphorylation and cell proliferation. •The nuclear CPI-17-PP1 axis plays a proliferative role in cells. -- Abstract: CPI-17 (C-kinase-activated protein phosphatase-1 (PP1) inhibitor, 17 kDa) is a cytoplasmic protein predominantly expressed in mature smooth muscle (SM) that regulates the myosin-associated PP1 holoenzyme (MLCP). Here, we show CPI-17 expression in proliferating cells, such as pancreatic cancer and hyperplastic SM cells. Immunofluorescence showed that CPI-17 was concentrated in nuclei of human pancreatic cancer (Panc1) cells. Nuclear accumulation of CPI-17 was also detected in the proliferating vascular SM cell culture and cells at neointima of rat vascular injury model. The N-terminal 21-residue tail domain of CPI-17 was necessary for the nuclear localization. Phospho-mimetic Asp-substitution of CPI-17 at Ser12 attenuated the nuclear import. CPI-17 phosphorylated at Ser12 was not localized at nuclei, suggesting a suppressive role of Ser12 phosphorylation in the nuclear import. Activated CPI-17 bound to all three isoforms of PP1 catalytic subunit in Panc1 nuclear extracts. CPI-17 knockdown in Panc1 resulted in dephosphorylation of histone H3 at Thr3, Ser10 and Thr11, whereas it had no effects on the phosphorylation of myosin light chain and merlin, the known targets of MLCP. In parallel, CPI-17 knockdown suppressed Panc1 proliferation. We propose that CPI-17 accumulated in the nucleus through the N-terminal tail targets multiple PP1 signaling pathways regulating cell proliferation

  7. Nuclear localization of CPI-17, a protein phosphatase-1 inhibitor protein, affects histone H3 phosphorylation and corresponds to proliferation of cancer and smooth muscle cells

    Eto, Masumi, E-mail: masumi.eto@jefferson.edu [Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, PA 19107 (United States); Kirkbride, Jason A.; Chugh, Rishika; Karikari, Nana Kofi [Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, PA 19107 (United States); Kim, Jee In [Department of Molecular Physiology and Biophysics, and Kimmel Cancer Center, Thomas Jefferson University, 1020 Locust Street, PA 19107 (United States); Cardiovascular Research Institute, Kyungpook National University School of Medicine, Daegu 700-422 (Korea, Republic of)

    2013-04-26

    Highlights: •Non-canonical roles of the myosin phosphatase inhibitor (CPI-17) were studied. •CPI-17 is localized in the nucleus of hyperplastic cancer and smooth muscle cells. •CPI-17 Ser12 phosphorylation may regulate the nuclear import. •CPI-17 regulates histone H3 phosphorylation and cell proliferation. •The nuclear CPI-17-PP1 axis plays a proliferative role in cells. -- Abstract: CPI-17 (C-kinase-activated protein phosphatase-1 (PP1) inhibitor, 17 kDa) is a cytoplasmic protein predominantly expressed in mature smooth muscle (SM) that regulates the myosin-associated PP1 holoenzyme (MLCP). Here, we show CPI-17 expression in proliferating cells, such as pancreatic cancer and hyperplastic SM cells. Immunofluorescence showed that CPI-17 was concentrated in nuclei of human pancreatic cancer (Panc1) cells. Nuclear accumulation of CPI-17 was also detected in the proliferating vascular SM cell culture and cells at neointima of rat vascular injury model. The N-terminal 21-residue tail domain of CPI-17 was necessary for the nuclear localization. Phospho-mimetic Asp-substitution of CPI-17 at Ser12 attenuated the nuclear import. CPI-17 phosphorylated at Ser12 was not localized at nuclei, suggesting a suppressive role of Ser12 phosphorylation in the nuclear import. Activated CPI-17 bound to all three isoforms of PP1 catalytic subunit in Panc1 nuclear extracts. CPI-17 knockdown in Panc1 resulted in dephosphorylation of histone H3 at Thr3, Ser10 and Thr11, whereas it had no effects on the phosphorylation of myosin light chain and merlin, the known targets of MLCP. In parallel, CPI-17 knockdown suppressed Panc1 proliferation. We propose that CPI-17 accumulated in the nucleus through the N-terminal tail targets multiple PP1 signaling pathways regulating cell proliferation.

  8. Proteomic analysis of human norepinephrine transporter complexes reveals associations with protein phosphatase 2A anchoring subunit and 14-3-3 proteins

    The norepinephrine transporter (NET) terminates noradrenergic signals by clearing released NE at synapses. NET regulation by receptors and intracellular signaling pathways is supported by a growing list of associated proteins including syntaxin1A, protein phosphatase 2A (PP2A) catalytic subunit (PP2A-C), PICK1, and Hic-5. In the present study, we sought evidence for additional partnerships by mass spectrometry-based analysis of proteins co-immunoprecipitated with human NET (hNET) stably expressed in a mouse noradrenergic neuroblastoma cell line. Our initial proteomic analyses reveal multiple peptides derived from hNET, peptides arising from the mouse PP2A anchoring subunit (PP2A-Ar) and peptides derived from 14-3-3 proteins. We verified physical association of NET with PP2A-Ar via co-immunoprecipitation studies using mouse vas deferens extracts and with 14-3-3 via a fusion pull-down approach, implicating specifically the hNET NH2-terminus for interactions. The transporter complexes described likely support mechanisms regulating transporter activity, localization, and trafficking

  9. Molecular dynamics simulations of protein-tyrosine phosphatase 1B. I. Ligand-induced changes in the protein motions

    Peters, Günther H. J.; Frimurer, T.M.; Andersen, J.N.;

    1999-01-01

    the protein were analyzed using the essential dynamics technique. Our results indicate that the predominately internal motions in PTP1B occur in a subspace of only a few degrees of freedom. Upon substrate binding, the flexibility of the protein is reduced by similar to 10%. The largest effect is found...

  10. Penostatin Derivatives, a Novel Kind of Protein Phosphatase 1B Inhibitors Isolated from Solid Cultures of the Entomogenous Fungus Isaria tenuipes

    Yu-Peng Chen

    2014-01-01

    Full Text Available Protein tyrosine phosphatase 1B (PTP1B is implicated as a negative regulator of insulin receptor (IR signaling and a potential drug target for the treatment of type II diabetes and other associated metabolic syndromes. Therefore, small molecular inhibitors of PTP1B can be considered as an attractive approach for the design of new therapeutic agents of type II diabetes diseases. In a continuing search for new protein phosphatase inhibitors from fungi, we have isolated a new compound, named penostatin J (1, together with three known ones, penostatin C (2, penostatin A (3, and penostatin B (4, from cultures of the entomogenous fungus Isaria tenuipes. The structure of penostatin J (1 was elucidated by extensive spectroscopic analysis. We also demonstrate for the first time that penostatin derivatives exhibit the best PTP1B inhibitory action. These findings suggest that penostatin derivatives are a potential novel kind of PTP1B inhibitors.

  11. Regulation of tumor cell migration by protein tyrosine phosphatase (PTP-proline-, glutamate-, serine-,and threonine-rich sequence (PEST

    Yanhua Zheng

    2013-02-01

    Full Text Available Protein tyrosine phosphatase (PTP-proline-, glutamate-, serine-, and threonine-rich sequence (PEST is ubiquitously expressed and is a critical regulator of cell adhesion and migration. PTP-PEST activity can be regulated transcriptionally via gene deletion or mutation in several types of human cancers or via post-translational modifications, including phosphorylation, oxidation, and caspase-dependent cleavage. PTP-PEST interacts with and dephosphorylates cytoskeletal and focal adhesion-associated proteins. Dephos-phorylation of PTP-PEST substrates regulates their enzymatic activities and/or their interaction with other proteins and plays an essential role in the tumor cell migration process.

  12. Regulation of tumor cell migration by protein tyrosine phosphatase (PTP)-proline-, glutamate-, serine-,and threonine-rich sequence (PEST)

    Yanhua Zheng; Zhimin Lu

    2013-01-01

    Protein tyrosine phosphatase (PTP)-proline-,glutamate-,serine-,and threonine-rich sequence (PEST) is ubiquitously expressed and is a critical regulator of cell adhesion and migration.PTP-PEST activity can be regulated transcriptionally via gene deletion or mutation in several types of human cancers or via post-translational modifications,including phosphorylation,oxidation,and caspase-dependent cleavage.PTP-PEST interacts with and dephosphorylates cytoskeletal and focal adhesion-associated proteins.Dephosphorylation of PTP-PEST substrates regulates their enzymatic activities and/or their interaction with other proteins and plays an essential role in the tumor cell migration process.

  13. Mechanical stimulation of C2C12 cells increases m-calpain expression, focal adhesion plaque protein degradation

    Grossi, Alberto; Karlsson, Anders H; Lawson, Moira Ann

    2008-01-01

    reorganization due to the activity of the ubiquitous proteolytic enzymes, calpains, has been reported. Whether there is a link between stretch- or load-induced signaling and calpain expression and activation is not known. Using a magnetic bead stimulation assay and C2C12 mouse myoblasts cell population, we have...

  14. Expression of protein tyrosine phosphatase alpha (RPTPalpha) in human breast cancer correlates with low tumor grade, and inhibits tumor cell growth in vitro and in vivo

    Ardini, E; Agresti, R; Tagliabue, E;

    2000-01-01

    Tyrosine phosphorylation is controlled by a balance of tyrosine kinases (PTKs) and protein tyrosine phosphatases (PTPs). Whereas the contribution of PTKs to breast tumorigenesis is the subject of intense scrutiny, the potential role of PTPs is poorly known. RPTPalpha is implicated in the activati...... delayed tumor growth and metastasis. To our knowledge, this is the first example of a study correlating expression level of a specific bona fide PTP with neoplastic disease status in humans....

  15. Investigation of Catalytic Loop Structure, Dynamics and Function Relationship of Yersinia Protein Tyrosine Phosphatase by Temperature-Jump Relaxation Spectroscopy and X-ray Structural Determination

    Ke, Shan; Ho, Meng-Chiao; Zhadin, Nickolay; Deng, Hua; Callender, Robert

    2012-01-01

    Yersinia Protein Tyrosine Phosphatase (YopH) is the most efficient enzyme amongst all PTPases and YopH is hyperactive compared to human PTPases, interferes with mammalian cellular pathways to achieve the pathogenicity of Yersinia. Two properties related to the catalytic loop structure differences have been proposed to affect its dynamics and enzyme efficiency. One is the ability of the loop to form stabilizing interactions to bound ligand after loop closure, which has long been recognized. In...

  16. Potential Utility of Sodium Selenate as an Adjunct to Metformin in Treating Type II Diabetes Mellitus in Rats: A Perspective on Protein Tyrosine Phosphatase

    Rania M. Salama; Schaalan, Mona F; Elkoussi, Alaaeldin A.; Khalifa, Amani E.

    2013-01-01

    Metformin is widely regarded as the standard first-line antidiabetic agent, in terms of efficacy and safety profiles. However, in most patients with type II diabetes mellitus (T2DM), it was found that metformin alone is not enough to adequately control hyperglycemia. Thus, we designed this study with the aim to investigate the effect of sodium selenate, a protein tyrosine phosphatase (PTP) inhibitor, individually and as an adjunct to metformin, on a rat model that simulates the metabolic char...

  17. Decreased expression of protein tyrosine phosphatase non-receptor type 12 is involved in the proliferation and recurrence of bladder transitional cell carcinoma

    PIAO, YONGRUI; LIU, XIANKUI; Lin, Zhenhua; Jin, Zhehu; JIN, XUANSHUN; Yuan, Kuichang; Wu, Wenyuan

    2015-01-01

    Protein tyrosine phosphatase non-receptor type 12 (PTPN12) has been shown to be involved in the development of a number of types of carcinoma. However, the effect of PTPN12 on the proliferation and recurrence of human bladder transitional cell carcinoma (TCC) is unclear. The present study aimed to investigate the expression and function of PTPN12 in human TCC. Samples from 164 patients with TCC, in addition to 146 patients undergoing bladder surgery for indications other than TCC, were examin...

  18. Involvement of Protein Tyrosine Phosphatases BcPtpA and BcPtpB in Regulation of Vegetative Development, Virulence and Multi-Stress Tolerance in Botrytis cinerea

    Yang, Qianqian; Yu, Fangwei; Yin, Yanni; Ma, Zhonghua

    2013-01-01

    Tyrosine phosphorylation and dephosphorylation have emerged as fundamentally important mechanisms of signal transduction and regulation in eukaryotic cells, governing many processes, but little has been known about their functions in filamentous fungi. In this study, we deleted two putative protein tyrosine phosphatase (PTP) genes (BcPTPA and BcPTPB) in Botrytis cinerea, encoding the orthologs of Saccharomyces cerevisiae Ptp2 and Ptp3, respectively. Although BcPtpA and BcPtpB have opposite fu...

  19. Cloning, purification, crystallization and preliminary X-ray analysis of two low-molecular-weight protein tyrosine phosphatases from Vibrio cholerae

    Two protein tyrosine phosphatases, namely VcLMWPTP-1 and VcLMWPTP-2, from V. cholerae have been cloned, expressed, purified and crystallized. Low-molecular-weight protein tyrosine phosphatases (LMWPTPs) are small cytoplasmic enzymes of molecular weight ∼18 kDa that belong to the large family of protein tyrosine phosphatases (PTPs). Despite their wide distribution in both prokaryotes and eukaryotes, their exact biological role in bacterial systems is not yet clear. Two low-molecular-weight protein tyrosine phosphatases (VcLMWPTP-1 and VcLMWPTP-2) from the Gram-negative bacterium Vibrio cholerae have been cloned, overexpressed, purified by Ni2+–NTA affinity chromatography followed by gel filtration and used for crystallization. Crystals of VcLMWPTP-1 were grown in the presence of ammonium sulfate and glycerol and diffracted to a resolution of 1.6 Å. VcLMWPTP-2 crystals were grown in PEG 4000 and diffracted to a resolution of 2.7 Å. Analysis of the diffraction data showed that the VcLMWPTP-1 crystals had symmetry consistent with space group P31 and that the VcLMWPTP-2 crystals had the symmetry of space group C2. Assuming the presence of four molecules in the asymmetric unit, the Matthews coefficient for the VcLMWPTP-1 crystals was estimated to be 1.97 Å3 Da−1, corresponding to a solvent content of 37.4%. The corresponding values for the VcLMWPTP-2 crystals, assuming the presence of two molecules in the asymmetric unit, were 2.77 Å3 Da−1 and 55.62%, respectively

  20. Association between serum alkaline phosphatase and C-reactive protein in the United States National Health and Nutrition Examination Survey 2005–2006

    Webber, Matthew; Krishnan, Aisling; Neil G. Thomas; Bernard M. Y. Cheung

    2009-01-01

    Background: Alkaline phosphatase (ALP) is a widely used marker for skeletal and hepatobiliary disorders, but its activity is also increased in atherosclerosis and peripheral vascular disease. It is an inflammatory marker like C-reactive protein (CRP). We therefore analyzed its relationship with CRP in the United States National Health and Nutrition Examination Survey (NHANES) 2005–2006. Methods: The analysis included 4155 men and non-pregnant women over the age of 20 years. The relationship ...

  1. Suppression of PKG by PDGF or nitric oxide in differentiated aortic smooth muscle cells: obligatory role of protein tyrosine phosphatase 1B

    Zhuang, Daming; Balani, Poonam; Pu, Qinghua; Thakran, Shalini; Hassid, Aviv

    2010-01-01

    Treatment of aortic smooth muscle cells with PDGF induces the upregulation of protein tyrosine phosphatase 1B (PTP1B). PTP1B, in turn, decreases the function of several growth factor receptors, thus completing a negative feedback loop. Studies have reported that PDGF induces the downregulation of PKG as part of a repertoire of dedifferentiation of vascular smooth muscle cells. Other studies have reported that chronic nitric oxide (NO) treatment also induces the downregulation of PKG. In the p...

  2. A fractionation method to identify qauntitative changes in protein expression mediated by IGF-1 on the proteome of murine C2C12 myoblasts

    Friedmann Theodore

    2009-08-01

    Full Text Available Abstract Although much is known about signal transduction downstream of insulin-like growth factor-1 (IGF-1, relatively little is known about the global changes in protein expression induced by this hormone. In this study, the acute effects of IGF-1 on the proteome of murine C2C12 cells were examined. Cells were treated with IGF-1 for up to 24 hours, lysed, and fractionated into cytosolic, nuclear, and insoluble portions. Proteins from the cytosolic fraction were further separated using a new batch ion-exchange chromatography method to reduce sample complexity, followed by two-dimensional (2D electrophoresis, and identification of selected proteins by mass spectrometry. PDQuest software was utilized to identify and catalogue temporal changes in protein expression during IGF-1 stimulation. In response to IGF-1 stimulation, expression of 23 proteins increased at least three-fold and expression of 17 proteins decreased at least three-fold compared with control un-stimulated C2C12 cells. Changes in expression of selected proteins from each group, including Rho-GDI, cofillin, RAD50, enolase, IκB kinase b (IκBKb and Hsp70 were confirmed by Western blotting. Additionally, the position of 136 'landmark' proteins whose expression levels and physicochemical properties did not change appreciably or consistently during IGF-1 treatment were mapped and identified. This characterization of large-scale changes in protein expression in response to growth factor stimulation of C2C12 cells will further help to establish a comprehensive understanding of the networks and pathways involved in the action of IGF-1.

  3. Involvement of β3A Subunit of Adaptor Protein-3 in Intracellular Trafficking of Receptor-like Protein Tyrosine Phosphatase PCP-2

    Hui DONG; Hong YUAN; Weirong JIN; Yan SHEN; Xiaojing XU; Hongyang WANG

    2007-01-01

    PCP-2 is a human receptor-like protein tyrosine phosphatase and a member of the MAM domain family cloned in human pancreatic adenocarcinoma cells. Previous studies showed that PCP-2 directly interacted with β-catenin through the juxtamembrane domain, dephosphorylated β-catenin and played an important role in the regulation of cell adhesion. Recent study showed that PCP-2 was also involved in the repression of β-catenin-induced transcriptional activity. Here we describe the interactions of PCP-2 with the β3A subunit of adaptor protein (AP)-3 and sorting nexin (SNX) 3. These protein complexes were detected using the yeast two-hybrid assay with the juxtamembrane and membrane-proximal catalytic domain of PCP-2 as "bait". Both AP-3 and SNX3 are molecules involved in intracellular trafficking of membrane receptors. The association between the β3A subunit of AP-3 and PCP-2 was further confirmed in mammalian cells. Our results suggested a possible mechanism of intracellular trafficking of PCP-2 mediated by AP-3 and SNX3 which might participate in the regulation of PCP-2 functions.

  4. Bypass of hexavalent chromium-induced growth arrest by a protein tyrosine phosphatase inhibitor: Enhanced survival and mutagenesis

    Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na2CrO4), the soluble oxyanionic dissolution product of certain particulate chromates, which are well-documented human respiratory carcinogens. In vitro soluble Cr(VI) induces a wide spectrum of DNA damage, in both the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate (SOV). Notably, SOV abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after SOV treatment was predominantly due to a bypass of cell cycle arrest, as there was no effect of the PTP inhibitor on Cr-induced apoptosis. Moreover, the SOV effect was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by SOV was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in Cr(VI)-induced expression of cell cycle promoting genes. Importantly, SOV resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of certain types of DNA damage may lead to increased genomic instability, via bypass of cell cycle checkpoints

  5. A Kelch Motif-Containing Serine/Threonine Protein Phosphatase Determines the Large Grain QTL Trait in Rice

    Zejun Hu; Haohua He; Shiyong Zhang; Fan Sun; Xiaoyun Xin; Wenxiang Wang; Xi Qian; Jingshui Yang; Xiaojin Luo

    2012-01-01

    A thorough understanding of the genetic basis of rice grain traits is critical for the improvement of rice (Oryza sativa L.) varieties.In this study,we generated an F2 population by crossing the large-grain japonica cultivar CW23 with Peiai 64 (PA64),an elite indica small-grain cultivar.Using QTL analysis,17 QTLs for five grain traits were detected on four different chromosomes.Eight of the QTLs were newly-identified in this study.In particular,qGL3-1,a newly-identified grain length QTL with the highest LOD value and largest phenotypic variation,was fine-mapped to the 17 kb region of chromosome 3.A serine/threonine protein phosphatase gene encoding a repeat domain containing two Kelch motifs was identified as the unique candidate gene corresponding to this QTL.A comparison of PA64 and CW23 sequences revealed a single nucleotide substitution (C→A) at position 1092 in exon 10,resulting in replacement of Asp (D) in PA64 with Glu (E) in CW23 for the 364th amino acid.This variation is located at the D position of the conserved sequence motif AVLDT of the Kelch repeat.Genetic analysis of a near-isogenic line (NIL) for qGL3-1 revealed that the allele qGL3-1 from CW23 has an additive or partly dominant effect,and is suitable for use in molecular marker-assisted selection.

  6. Protein tyrosine phosphatase 1B deficiency ameliorates murine experimental colitis via the expansion of myeloid-derived suppressor cells.

    Jing Zhang

    Full Text Available Protein tyrosine phosphatase 1B (PTP1B is a key molecule in modulating low-degree inflammatory conditions such as diabetes. The role of PTP1B in other chronic inflammations, however, remains unknown. Here, we report that PTP1B deficiency ameliorates Dextran Sulfate Sodium (DSS-induced murine experimental colitis via expanding CD11b(+Gr-1(+ myeloid-derived suppressor cells (MDSCs. Employing DSS-induced murine experimental colitis as inflammatory animal model, we found that, compared with wild-type littermates, PTP1B-null mice demonstrated greater resistance to DSS-induced colitis, as reflected by slower weight-loss, greater survival rates and decreased PMN and macrophage infiltration into the colon. The evidence collectively also demonstrated that the resistance of PTP1B-null mice to DSS-induced colitis is based on the expansion of MDSCs. First, PTP1B-null mice exhibited a greater frequency of MDSCs in the bone marrow (BM, peripheral blood and spleen when compared with wild-type littermates. Second, PTP1B levels in BM leukocytes were significantly decreased after cells were induced into MDSCs by IL-6 and GM-CSF, and the MDSC induction occurred more rapidly in PTP1B-null mice than in wild-type littermates, suggesting PTP1B as a negative regulator of MDSCs. Third, the adoptive transfer of MDSCs into mice with DSS-colitis significantly attenuated colitis, which accompanies with a decreased serum IL-17 level. Finally, PTP1B deficiency increased the frequency of MDSCs from BM cells likely through enhancing the activities of signal transducer and activator of transcription 3 (STAT3 and Janus kinase 2 (JAK2. In conclusion, our study provides the first evidences that PTP1B deficiency ameliorates murine experimental colitis via expanding MDSCs.

  7. Mitogen activated protein kinase phosphatase-1 prevents the development of tactile sensitivity in a rodent model of neuropathic pain

    Ndong Christian

    2012-04-01

    Full Text Available Abstract Background Neuropathic pain due to nerve injury is one of the most difficult types of pain to treat. Following peripheral nerve injury, neuronal and glial plastic changes contribute to central sensitization and perpetuation of mechanical hypersensitivity in rodents. The mitogen activated protein kinase (MAPK family is pivotal in this spinal cord plasticity. MAPK phosphatases (MKPs limit inflammatory processes by dephosphorylating MAPKs. For example, MKP-1 preferentially dephosphorylates p-p38. Since spinal p-p38 is pivotal for the development of chronic hypersensitivity in rodent models of pain, and p-p38 inhibitors have shown clinical potential in acute and chronic pain patients, we hypothesize that induction of spinal MKP-1 will prevent the development of peripheral nerve-injury-induced hypersensitivity and p-p38 overexpression. Results We cloned rat spinal cord MKP-1 and optimize MKP-1 cDNA in vitro using transfections to BV-2 cells. We observed that in vitro overexpression of MKP-1 blocked lipopolysaccharide-induced phosphorylation of p38 (and other MAPKs as well as release of pro-algesic effectors (i.e., cytokines, chemokines, nitric oxide. Using this cDNA MKP-1 and a non-viral, in vivo nanoparticle transfection approach, we found that spinal cord overexpression of MKP-1 prevented development of peripheral nerve-injury-induced tactile hypersensitivity and reduced pro-inflammatory cytokines and chemokines and the phosphorylated form of p38. Conclusions Our results indicate that MKP-1, the natural regulator of p-p38, mediates resolution of the spinal cord pro-inflammatory milieu induced by peripheral nerve injury, resulting in prevention of chronic mechanical hypersensitivity. We propose that MKP-1 is a potential therapeutic target for pain treatment or prevention.

  8. Bypass of hexavalent chromium-induced growth arrest by a protein tyrosine phosphatase inhibitor: Enhanced survival and mutagenesis

    Bae, Dongsoon; Camilli, Tura C. [Department of Pharmacology and Physiology, George Washington University Medical Center, Washington, DC (United States); Chun, Gina; Lal, Madhu; Wright, Kristen [Department of Pharmacology and Physiology, George Washington University Medical Center, Washington, DC (United States); Program in Molecular Medicine, George Washington University Medical Center, Washington, DC (United States); O' Brien, Travis J. [Department of Pharmacology and Physiology, George Washington University Medical Center, Washington, DC (United States); Program in Molecular Medicine, George Washington University Medical Center, Washington, DC (United States); GW Cancer Institute, George Washington University Medical Center, Washington, DC (United States); Patierno, Steven R. [Department of Pharmacology and Physiology, George Washington University Medical Center, Washington, DC (United States); Department of Medicine, George Washington University Medical Center, Washington, DC (United States); Program in Molecular Medicine, George Washington University Medical Center, Washington, DC (United States); GW Cancer Institute, George Washington University Medical Center, Washington, DC (United States); Ceryak, Susan [Department of Pharmacology and Physiology, George Washington University Medical Center, Washington, DC (United States); Department of Medicine, George Washington University Medical Center, Washington, DC (United States); Program in Molecular Medicine, George Washington University Medical Center, Washington, DC (United States); GW Cancer Institute, George Washington University Medical Center, Washington, DC (United States)], E-mail: phmsmc@gwumc.edu

    2009-01-15

    Although the consequences of genotoxic injury include cell cycle arrest and apoptosis, cell survival responses after genotoxic injury can produce intrinsic death-resistance and contribute to the development of a transformed phenotype. Protein tyrosine phosphatases (PTPs) are integral components of key survival pathways, and are responsible for their inactivation, while PTP inhibition is often associated with enhanced cell proliferation. Our aim was to elucidate signaling events that modulate cell survival after genotoxin exposure. Diploid human lung fibroblasts (HLF) were treated with Cr(VI) (as Na{sub 2}CrO{sub 4}), the soluble oxyanionic dissolution product of certain particulate chromates, which are well-documented human respiratory carcinogens. In vitro soluble Cr(VI) induces a wide spectrum of DNA damage, in both the presence and absence of a broad-range PTP inhibitor, sodium orthovanadate (SOV). Notably, SOV abrogated Cr(VI)-induced clonogenic lethality. The enhanced survival of Cr(VI)-exposed cells after SOV treatment was predominantly due to a bypass of cell cycle arrest, as there was no effect of the PTP inhibitor on Cr-induced apoptosis. Moreover, the SOV effect was not due to decreased Cr uptake as evidenced by unchanged Cr-DNA adduct burden. Additionally, the bypass of Cr-induced growth arrest by SOV was accompanied by a decrease in Cr(VI)-induced expression of cell cycle inhibiting genes, and an increase in Cr(VI)-induced expression of cell cycle promoting genes. Importantly, SOV resulted in an increase in forward mutations at the HPRT locus, supporting the hypothesis that PTP inhibition in the presence of certain types of DNA damage may lead to increased genomic instability, via bypass of cell cycle checkpoints.

  9. Protein tyrosine phosphatase is possibly involved in cellular signal transduction and the regulation of ABA accumulation in response to water deficit in Maize L. coleoptile

    2003-01-01

    Water deficit-induced ABA accumulation is an ideal model or "stimulus-response" system to investigate cellular stress signaling in plant cells, using such a model the cellular stress signaling triggered by water deficit was investigated in Maize L. coleoptile. Water deficit-induced ABA accumulation was sensitively blocked by NaVO3, a potent inhibitor both to plasma membrane H+-ATPase (PM-H+- ATPase) and protein tyrosine phosphatase (PTPase). However, while PM- H+-ATPase activity was unaffected under water deficit and PM- H+-ATPase activator did not induce an ABA accumulation instead of water deficit, water deficit induced an increase in the protein phosphatase activity, and furthermore, ABA accumulation was inhibited by PAO, a specific inhibitor of PTPase. These results indicate that protein phosphtases may be involved in the cellular signaling in response to water deficit. Further studies identified at least four species of protein phosphtase as assayed by using pNPP as substrate, among which one component was especially sensitive to NaVO3. The NaVO3-sensitive enzyme was purified and finally showed a protein band about 66 kD on SDS/PAGE. The purified enzyme showed a great activity to some specific PTPase substrates at pH 6.0. In addition to NaVO3, the enzyme was also sensitive to some other PTPase inhibitors such as Zn2+ and MO33+, but not to Ca2+ and Mg2+, indicating that it might be a protein tyrosine phosphatase. Interestingly, the purified enzyme could be deactivated by some reducing agent DTT, which was previously proved to be an inhibitor of water deficit-induced ABA accumulation. This result further proved that PTPase might be involved in the cellular signaling of ABA accumulation in response to water deficit.

  10. The Myoblast C2C12 Transfected with Mutant Valosin-Containing Protein Exhibits Delayed Stress Granule Resolution on Oxidative Stress.

    Rodriguez-Ortiz, Carlos J; Flores, Julio C; Valenzuela, Joanna A; Rodriguez, Gema J; Zumkehr, Joannee; Tran, Diana N; Kimonis, Virginia E; Kitazawa, Masashi

    2016-06-01

    Valosin-containing protein (VCP) mutations cause inclusion body myopathy with Paget disease and frontotemporal dementia. However, the mechanisms by which mutant VCP triggers degeneration remain unknown. Here, we investigated the role of VCP in cellular stress and found that the oxidative stressor arsenite and heat shock-activated stress responses evident by T-intracellular antigen-1-positive granules in C2C12 myoblasts. Granules also contained phosphorylated transactive response DNA-binding protein 43, ubiquitin, microtubule-associated protein 1A/1B light chains 3, and lysosome-associated membrane protein 2. Mutant VCP produced more T-intracellular antigen-1-positive granules than wild-type in the postarsenite exposure period. Similar results were observed for other granule components, indicating that mutant VCP delayed clearance of stress granules. Furthermore, stress granule resolution was impaired on differentiated C2C12 cells expressing mutant VCP. To address whether mutant VCP triggers dysregulation of the stress granule pathway in vivo, we analyzed skeletal muscle of aged VCPR155H-knockin mice. We found significant increments in oxidated proteins but observed the stress granule markers RasGAP SH3-binding protein and phosphorylated eukaryotic translation initiation factor 2α unchanged. The mixed results indicate that mutant VCP together with aging lead to higher oxidative stress in skeletal muscle but were insufficient to disrupt the stress granule pathway. Our findings support that deficiencies in recovery from stressors may result in attenuated tolerance to stress that could trigger muscle degeneration. PMID:27106764

  11. The Molecular Details of WPD-Loop Movement Differ in the Protein-Tyrosine Phosphatases YopH and PTP1B†

    Brandão, Tiago A. S.; Johnson, Sean J.; Hengge, Alvan C.

    2012-01-01

    The movement of a conserved protein loop (the WPD-loop) is important in catalysis by protein tyrosine phosphatases (PTPs). Using kinetics, isotope effects, and X-ray crystallography, the different effects arising from mutation of the conserved tryptophan in the WPD-loop were compared in two PTPs, the human PTP1B, and the bacterial YopH from Yersinia. Mutation of the conserved tryptophan in the WPD-loop to phenylalanine has a negligible effect on kcat in PTP1B and full loop movement is maintai...

  12. Immobilized Cytochrome P450 2C9 (CYP2C9): Applications for Metabolite Generation, Monitoring Protein-Protein Interactions, and Improving In-vivo Predictions Using Enhanced In-vitro Models

    Wollenberg, Lance A.

    Cytochrome P450 (P450) enzymes are a family of oxoferroreductase enzymes containing a heme moiety and are well known to be involved in the metabolism of a wide variety of endogenous and xenobiotic materials. It is estimated that roughly 75% of all pharmaceutical compounds are metabolized by these enzymes. Traditional reconstituted in-vitro incubation studies using recombinant P450 enzymes are often used to predict in-vivo kinetic parameters of a drug early in development. However, in many cases, these reconstituted incubations are prone to aggregation which has been shown to affect the catalytic activity of an enzyme. Moreover, the presence of other isoforms of P450 enzymes present in a metabolic incubation, as is the case with microsomal systems, may affect the catalytic activity of an enzyme through isoform-specific protein-protein interactions. Both of these effects may result in inaccurate prediction of in-vivo drug metabolism using in-vitro experiments. Here we described the development of immobilized P450 constructs designed to elucidate the effects of aggregation and protein-protein interactions between P450 isoforms on catalytic activities. The long term objective of this project is to develop a system to control the oligomeric state of Cytochrome P450 enzymes to accurately elucidate discrepancies between in vitro reconstituted systems and actual in vivo drug metabolism for the precise prediction of metabolic activity. This approach will serve as a system to better draw correlations between in-vivo and in-vitro drug metabolism data. The central hypothesis is that Cytochrome P450 enzymes catalytic activity can be altered by protein-protein interactions occurring between Cytochrome P450 enzymes involved in drug metabolism, and is dependent on varying states of protein aggregation. This dissertation explains the details of the construction and characterization of a nanostructure device designed to control the state of aggregation of a P450 enzyme. Moreover

  13. Whole genome sequencing identifies a deletion in protein phosphatase 2A that affects its stability and localization in Chlamydomonas reinhardtii.

    Huawen Lin

    Full Text Available Whole genome sequencing is a powerful tool in the discovery of single nucleotide polymorphisms (SNPs and small insertions/deletions (indels among mutant strains, which simplifies forward genetics approaches. However, identification of the causative mutation among a large number of non-causative SNPs in a mutant strain remains a big challenge. In the unicellular biflagellate green alga Chlamydomonas reinhardtii, we generated a SNP/indel library that contains over 2 million polymorphisms from four wild-type strains, one highly polymorphic strain that is frequently used in meiotic mapping, ten mutant strains that have flagellar assembly or motility defects, and one mutant strain, imp3, which has a mating defect. A comparison of polymorphisms in the imp3 strain and the other 15 strains allowed us to identify a deletion of the last three amino acids, Y313F314L315, in a protein phosphatase 2A catalytic subunit (PP2A3 in the imp3 strain. Introduction of a wild-type HA-tagged PP2A3 rescues the mutant phenotype, but mutant HA-PP2A3 at Y313 or L315 fail to rescue. Our immunoprecipitation results indicate that the Y313, L315, or YFLΔ mutations do not affect the binding of PP2A3 to the scaffold subunit, PP2A-2r. In contrast, the Y313, L315, or YFLΔ mutations affect both the stability and the localization of PP2A3. The PP2A3 protein is less abundant in these mutants and fails to accumulate in the basal body area as observed in transformants with either wild-type HA-PP2A3 or a HA-PP2A3 with a V310T change. The accumulation of HA-PP2A3 in the basal body region disappears in mated dikaryons, which suggests that the localization of PP2A3 may be essential to the mating process. Overall, our results demonstrate that the terminal YFL tail of PP2A3 is important in the regulation on Chlamydomonas mating.

  14. Type 1 protein phosphatase acts in opposition to IpL1 protein kinase in regulating yeast chromosome segregation.

    Francisco, L; Wang, W.; Chan, C S

    1994-01-01

    The IPL1 gene is required for high-fidelity chromosome segregation in the budding yeast Saccharomyces cerevisiae. Conditional ipl1ts mutants missegregate chromosomes severely at 37 degrees C. Here, we report that IPL1 encodes an essential putative protein kinase whose function is required during the later part of each cell cycle. At 26 degrees C, the permissive growth temperature, ipl1 mutant cells are defective in the recovery from a transient G2/M-phase arrest caused by the antimicrotubule ...

  15. cDNA isolated from a human T-cell library encodes a member of the protein-tyrosine-phosphatase family

    A human peripheral T-cell cDNA library was screened with two labeled synthetic oligonucleotides encoding regions of a human placenta protein-tyrosine-phosphatase. One positive clone was isolated and the nucleotide sequence was determined. It contained 1,305 base pairs of open reading frame followed by a TAA stop codon and 978 base pairs of 3' untranslated end, although a poly(A)+ tail was not found. An initiator methionine residue was predicted at position 61, which would result in a protein of 415 amino acid residues. This was supported by the synthesis of a Mr 48,000 protein in an in vitro reticulocyte lysate translation system using RNA transcribed from the cloned cDNA and T7 RNA polymerase. The deduced amino acid sequence was compared to other known proteins revealing 65% identity to the low Mr PTPase 1B isolated from placenta. In view of the high degree of similarity, the T-cell cDNA likely encodes a newly discovered protein-tyrosine-phosphatase, thus expanding this family of genes

  16. Potential role of lncRNA cyp2c91-protein interactions on diseases of the immune system

    Suravajhala, Prashanth; Kogelman, Lisette J. A.; Mazzoni, Gianluca; Kadarmideen, Haja N

    2015-01-01

    With unprecedented increase in next generation sequencing technologies, there has been a persistent interest on transcript profiles of long non-coding RNAs (lncRNAs) and protein-coding genes forming an interaction network. Apart from protein–protein interaction (PPI), gene network models such as Weighted Gene Co-expression Network Analysis (WGCNA) are used to functionally annotate lncRNAs in identifying their potential disease associations. To address this, studies have led to characterizing ...

  17. Regulation of Src family kinases involved in T cell receptor signaling by protein-tyrosine phosphatase CD148

    Štěpánek, Ondřej; Kalina, T.; Dráber, Peter; Skopcová, Tereza; Svojgr, K.; Angelisová, Pavla; Hořejší, Václav; Weiss, A.; Brdička, Tomáš

    2011-01-01

    Roč. 286, č. 25 (2011), s. 22101-22112. ISSN 0021-9258 R&D Projects: GA MŠk 2B06064; GA MŠk 1M0506 Institutional research plan: CEZ:AV0Z50520514 Keywords : CD148 * tyrosine phosphatase * Src family kinases Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.773, year: 2011

  18. Purkinje cell-specific knockout of the protein phosphatase PP2B impairs potentiation and cerebellar motor learning

    M. Schonewille (Martijn); A. Belmeguenai; S.K.E. Koekkoek (Bas); S.H. Houtman (Simone Hendrika); H.J. Boele (Henk-Jan); B.J. van Beugen (Boeke); Z. Gao (Zhenyu); A.M. Badura (Aleksandra); G. Ohtsuki (Gen); W.E. Amerika; E. Hosy; F.E. Hoebeek (Freek); Y. Elgersma (Ype); C.R.W. Hansel (Christian); C.I. de Zeeuw (Chris)

    2010-01-01

    textabstractCerebellar motor learning is required to obtain procedural skills. Studies have provided supportive evidence for a potential role of kinase-mediated long-term depression (LTD) at the parallel fiber to Purkinje cell synapse in cerebellar learning. Recently, phosphatases have been implicat

  19. Inhibition of protein phosphatase 2A induces serine/threonine phosphorylation, subcellular redistribution, and functional inhibition of STAT3

    Woetmann, A; Nielsen, M; Christensen, S T; Brockdorff, J; Kaltoft, K; Engel, A M; Skov, S; Brender, C; Geisler, C; Svejgaard, A; Rygaard, J; Leick, V; Odum, N

    1999-01-01

    that serine phosphorylation of STATs also is involved in the regulation of STAT-mediated gene transcription. Here, we studied the role of serine/threonine phosphatases in STAT3 signaling in human antigen-specific CD4(+) T cell lines and cutaneous T cell lymphoma lines, expressing a constitutively...

  20. Purification and Characterization of the Catalytic Domain of Protein Tyrosine Phosphatase SHP-1 and the Preparation of Anti-△SHP-1 Antibodies

    LI Wan-nan; ZHUANG Yan; LI He; SUN Ying; FU Yao; WU Xiao-xia; ZHAO Zhi-zhuang; FU Xue-qi

    2008-01-01

    This study is focused on the expression of an SH2 domain-truncated form of protein tyrosine phosphatase SHP-1(designated △SHP-1) and the preparation of its polyelonal antibodies.A cDNA fragment encoding △SHP-1 was amplified by PCR and then cloned into the pT7 expression vector.The recombinant pT7-△SHP-1 plasmid was used to transform Rosetta(DE3) E.coll cells.△SHP-1 was distributed in the exclusion body of E.coll cell extracts and was purified through a two-column chromatographic procedure.The purified enzyme exhibited an expected molecular weight on SDS-gels and HPLC gel filtration columns.It possesses robust tyrosine phosphatase activity and shows typical enzymatic characteristics of classic tyrosine phosphatases.To generate polyclonal anti-△SHP-1 antibodies,purified recombinant △SHP-1 was used to immunize a rabbit.The resultant anti-serum was subjected to purification on △SHP-1 antigen affinity chromatography.The purified polyclonal antibody displayed a high sensitivity and specificity toward △SHP-1.This study thus provides the essential materials for further investigating the biological function and pathological implication of SHP-1 and screening the inhibitors and activators of the enzyme for therapeutic drug development.

  1. AN INTRA - ABDOMINAL FOREI GN BOCORRELATION OF SERUM LIPID PROFILE, SERUM CALCIUM, ALKALINE PHOSPHATASE AND SERUM PROTEIN WITH HISTOPATHOLOGICAL GRADING AND STAGING IN HEAD AND NECK CANCER

    Neha

    2014-02-01

    Full Text Available Lipids have a key role in the maintenance of cell integrity. Hypolipidemia is related with increased risk of cancer and mortality. Elevated calcium and alkaline phosphatase has also been seen in cancer patients having m etastasis. Alteration in serum prote ins also has been reported. Hence present study was undertaken in 100 histopathologically confirmed head and neck cancer patients, in Department of Pathology Gandhi Medical College Bhopal, after taking informed written c onsent and ethical clearance. Lipid Profile, Serum Calcium, Alkaline Phosphatase, Serum Protein with Albumin were estimated and compared with age and sex matched healthy controls. Statistical analysis was done using chi square test. Total cholesterol (TC, high density lipoprotein - cholesterol (HDLC, low density lipoprotein - cholesterol (LDLC, Very low density lipoprotein - cholesterol (VLDLC all decreased in head & neck cancer patients. Hypercalcemia was seen in 35% of patients. Raised Alkaline phosphatase (ALP was seen in 8 % cancer patients. Serum calcium was found to be increasing with advancing stage. Further studies should be carried out in large number of patients to confirm the role of these parameters with special attention to modifiable ones and their relation with staging and grading of cancer, which can be used as prognostic markers.

  2. Protein tyrosine phosphatase 1B inhibitory activity of Indonesian herbal medicines and constituents of Cinnamomum burmannii and Zingiber aromaticum.

    Saifudin, Azis; Kadota, Shigetoshi; Tezuka, Yasuhiro

    2013-04-01

    We screened water and methanol extracts of 28 Indonesian medicinal plants for their protein tyrosine phosphatase 1B (PTP1B) inhibitory activities. Nine water extracts, i.e., Alstonia scholaris leaf, Blumea balsamifera, Cinnamomum burmannii, Cymbopogon nardus, Melaleuca leucadendra, Phyllanthus niruri, Piper nigrum, Syzygium aromaticum, and Sy. polyanthum, exhibited ≥70 % inhibition at 25 μg/mL, whereas 11 methanol extracts, i.e., Als. scholaris, Andrographis paniculata, B. balsamifera, Ci. burmannii, Curcuma heyneana, Glycyrrhiza glabra, M. leucadendra, Punica granatum, Rheum palmatum, Sy. polyanthum, and Z. aromaticum, exhibited ≥70 % inhibition at 25 μg/mL. Water extracts of B. balsamifera (IC50, 2.26 μg/mL) and M. leucadendra (IC50, 2.05 μg/mL), and methanol extracts of Ci. burmannii (IC50, 2.47 μg/mL), Pu. granatum (IC50, 2.40 μg/mL), and Sy. polyanthum (IC50, 1.03 μg/mL) exhibited strong inhibitory activity, which was comparable with that of the positive control, RK-682 (IC50, 2.05 μg/mL). The PTP1B inhibitory activity of the constituents of Ci. burmannii and Z. aromaticum was then evaluated. 5'-Hydroxy-5-hydroxymethyl-4″,5″-methylenedioxy-1,2,3,4-dibenzo-1,3,5-cycloheptatriene (2; IC50, 29.7 μM) and trans-cinnamaldehyde (5; IC50, 57.6 μM) were the active constituents of Ci. burmannii, while humulatrien-5-ol-8-one (21; IC50, 27.7 μM), kaempferol-3,4'-di-O-methyl ether (32; IC50, 17.5 μM), and (S)-6-gingerol (33; IC50, 28.1 μM) were those of Z. aromaticum. These results suggest that these medicinal plants may contribute to the treatment and/or prevention of type II diabetes and/or obesity through PTP1B inhibition. PMID:22645080

  3. Two homologous putative protein tyrosine phosphatases, OsPFA-DSP2 and AtPFA-DSP4, negatively regulate the pathogen response in transgenic plants.

    Hanjie He

    Full Text Available Protein phosphatases, together with protein kinases, regulate protein phosphorylation and dephosphorylation, and play critical roles in plant growth and biotic stress responses. However, little is known about the biological functions of plant protein tyrosine dual-specificity phosphatase (PFA-DSP in biotic stresses. Here, we found that OsPFA-DSP2 was mainly expressed in calli, seedlings, roots, and young panicles, and localized in cytoplasm and nucleus. Ectopic overexpression of OsPFA-DSP2 in rice increased sensitivity to Magnaporthe grisea (M. grisea Z1 strain, inhibited the accumulation of hydrogen peroxide (H(2O(2 and suppressed the expression of pathogenesis-related (PR genes after fungal infection. Interestingly, transgenic Arabidopsis plants overexpressing AtPFA-DSP4, which is homologous to OsPFA-DSP2, also exhibited sensitivity to Pseudomonas syringae pv. tomato DC3000 (Pst DC3000, reduced accumulation of H(2O(2 and decreased photosynthesic capacity after infection compared with Col-0. These results indicate that OsPFA-DSP2 and AtPFA-DSP4 act as negative regulators of the pathogen response in transgenic plants.

  4. Foot and mouth disease virus non structural protein 2C interacts with Beclin1 modulating virus replication

    Foot-and-mouth disease virus (FMDV), the causative agent of foot-and-mouth disease (FMD), is an Apthovirus within the Picornaviridae family. Replication of the virus occurs in association with replication complexes that are formed by host cell membrane rearrangements. The largest viral protein in th...

  5. Hailey-Hailey disease: identification of novel mutations in ATP2C1 and effect of missense mutation A528P on protein expression levels.

    Fairclough, Rebecca J; Lonie, Lorne; Van Baelen, Kurt; Haftek, Marek; Munro, Colin S; Burge, Susan M; Hovnanian, Alain

    2004-07-01

    ATP2C1, encoding the human secretory pathway Ca(2+)-ATPase (hSPCA1), was recently identified as the defective gene in Hailey-Hailey disease (HHD), an autosomal dominant skin disorder characterized by abnormal keratinocyte adhesion in the suprabasal layers of the epidermis. In this study, we used denaturing high-performance liquid chromatography to screen all 28 exons and flanking intron boundaries of ATP2C1 for mutations in 9 HHD patients. Nine different mutations were identified. Five of these mutations, including one nonsense, one deletion, two splice-site, and one missense mutation, have not been previously reported. Recently, functional analysis of a series of site-specific mutants, designed to mimic missense mutations found in ATP2C1, uncovered specific defects in Ca(2+) and/or Mn(2+) transport and protein expression in mutant hSPCA1 polypeptides. In order to investigate the molecular and physiological basis of HHD in the patient carrying missense mutation A528P, located in the putative nucleotide binding domain of the molecule, site-directed mutagenesis was employed to introduce this mutation into the wild-type ATP2C1 (hSPCA1) sequence. Functional analyses of HHD-mutant A528P demonstrated a low level of protein expression, despite normal levels of mRNA and correct targeting to the Golgi, suggesting instability or abnormal folding of the mutated hSPCA1 polypeptides. Analogous to conclusions drawn from our previous studies, these results further support the theory of haploinsufficiency as a prevalent mechanism for the dominant inheritance of HHD, by suggesting that the level of hSPCA1 in epidermal cells is critical. PMID:15191544

  6. Theophylline Represses IL-8 Secretion from Airway Smooth Muscle Cells Independently of Phosphodiesterase Inhibition. Novel Role as a Protein Phosphatase 2A Activator.

    Patel, Brijeshkumar S; Rahman, Md Mostafizur; Rumzhum, Nowshin N; Oliver, Brian G; Verrills, Nicole M; Ammit, Alaina J

    2016-06-01

    Theophylline is an old drug experiencing a renaissance owing to its beneficial antiinflammatory effects in chronic respiratory diseases, such as asthma and chronic obstructive pulmonary disease. Multiple modes of antiinflammatory action have been reported, including inhibition of the enzymes that degrade cAMP-phosphodiesterase (PDE). Using primary cultures of airway smooth muscle (ASM) cells, we recently revealed that PDE4 inhibitors can potentiate the antiinflammatory action of β2-agonists by augmenting cAMP-dependent expression of the phosphatase that deactivates mitogen-activated protein kinase (MAPK)-MAPK phosphatase (MKP)-1. Therefore, the aim of this study was to address whether theophylline repressed cytokine production in a similar, PDE-dependent, MKP-1-mediated manner. Notably, theophylline did not potentiate cAMP release from ASM cells treated with the long-acting β2-agonist formoterol. Moreover, theophylline (0.1-10 μM) did not increase formoterol-induced MKP-1 messenger RNA expression nor protein up-regulation, consistent with the lack of cAMP generation. However, theophylline (at 10 μM) was antiinflammatory and repressed secretion of the neutrophil chemoattractant cytokine IL-8, which is produced in response to TNF-α. Because theophylline's effects were independent of PDE4 inhibition or antiinflammatory MKP-1, we then wished to elucidate the novel mechanisms responsible. We investigated the impact of theophylline on protein phosphatase (PP) 2A, a master controller of multiple inflammatory signaling pathways, and show that theophylline increases TNF-α-induced PP2A activity in ASM cells. Confirmatory results were obtained in A549 lung epithelial cells. PP2A activators have beneficial effects in ex vivo and in vivo models of respiratory disease. Thus, our study is the first to link theophylline with PP2A activation as a novel mechanism to control respiratory inflammation. PMID:26574643

  7. microRNA-183 plays as oncogenes by increasing cell proliferation, migration and invasion via targeting protein phosphatase 2A in renal cancer cells

    Highlights: • miR-183 was up-regulated in renal cancer tissues. • Inhibition of endogenous miR-183 suppressed renal cancer cell growth and metastasis. • miR-183 increased cell growth and metastasis. • miR-183 regulated renal cancer cell growth and metastasis via directly targeting tumor suppressor protein phosphatase 2A. - Abstract: The aim of this study was to investigate the function of miR-183 in renal cancer cells and the mechanisms miR-183 regulates this process. In this study, level of miR-183 in clinical renal cancer specimens was detected by quantitative real-time PCR. miR-183 was up- and down-regulated in two renal cancer cell lines ACHN and A498, respectively, and cell proliferation, Caspase 3/7 activity, colony formation, in vitro migration and invasion were measured; and then the mechanisms of miR-183 regulating was analyzed. We found that miR-183 was up-regulated in renal cancer tissues; inhibition of endogenous miR-183 suppressed in vitro cell proliferation, colony formation, migration, and invasion and stimulated Caspase 3/7 activity; up-regulated miR-183 increased cell growth and metastasis and suppressed Caspase 3/7 activity. We also found that miR-183 directly targeted tumor suppressor, specifically the 3′UTR of three subunits of protein phosphatase 2A (PP2A-Cα, PP2A-Cβ, and PP2A-B56-γ) transcripts, inhibiting their expression and regulated the downstream regulators p21, p27, MMP2/3/7 and TIMP1/2/3/4. These results revealed the oncogenes role of miR-183 in renal cancer cells via direct targeting protein phosphatase 2A

  8. Adipocyte-Specific Protein Tyrosine Phosphatase 1B Deletion Increases Lipogenesis, Adipocyte Cell Size and is a Minor Regulator of Glucose Homeostasis

    Carl Owen; Alicja Czopek; Abdelali Agouni; Louise Grant; Robert Judson; Lees, Emma K; George D Mcilroy; Olga Göransson; Andy Welch; Bence, Kendra K.; Kahn, Barbara B.; Neel, Benjamin G.; Nimesh Mody; Mirela Delibegović

    2012-01-01

    Protein tyrosine phosphatase 1B (PTP1B), a key negative regulator of leptin and insulin signaling, is positively correlated with adiposity and contributes to insulin resistance. Global PTP1B deletion improves diet-induced obesity and glucose homeostasis via enhanced leptin signaling in the brain and increased insulin signaling in liver and muscle. However, the role of PTP1B in adipocytes is unclear, with studies demonstrating beneficial, detrimental or no effect(s) of adipose-PTP1B-deficiency...

  9. Nuclear Export and Centrosome Targeting of the Protein Phosphatase 2A Subunit B56α: ROLE OF B56α IN NUCLEAR EXPORT OF THE CATALYTIC SUBUNIT*

    Flegg, Cameron P.; Sharma, Manisha; Medina-Palazon, Cahora; Jamieson, Cara; Galea, Melanie; Brocardo, Mariana G.; Mills, Kate; Henderson, Beric R.

    2010-01-01

    Protein phosphatase (PP) 2A is a heterotrimeric enzyme regulated by specific subunits. The B56 (or B′/PR61/PPP2R5) class of B-subunits direct PP2A or its substrates to different cellular locations, and the B56α, -β, and -ϵ isoforms are known to localize primarily in the cytoplasm. Here we studied the pathways that regulate B56α subcellular localization. We detected B56α in the cytoplasm and nucleus, and at the nuclear envelope and centrosomes, and show that cytoplasmic localization is depende...

  10. The Spinocerebellar Ataxia 12 Gene Product and Protein Phosphatase 2A Regulatory Subunit Bβ2 Antagonizes Neuronal Survival by Promoting Mitochondrial Fission*S⃞

    Dagda, Ruben K.; Merrill, Ronald A.; Cribbs, J. Thomas; Chen, Yucui; Hell, Johannes W; Usachev, Yuriy M.; Strack, Stefan

    2008-01-01

    The neurodegenerative disorder spinocerebellar ataxia 12 (SCA12) is caused by CAG repeat expansion in the non-coding region of the PPP2R2B gene. PPP2R2B encodes Bβ1 and Bβ2, alternatively spliced and neuron-specific regulatory subunits of the protein phosphatase 2A (PP2A) holoenzyme. We show here that in PC12 cells and hippocampal neurons, cell stressors induced a rapid translocation of PP2A/Bβ2 to mitochondria to promote apoptosis. Conversely, silencing of PP2A/Bβ2 pr...

  11. Purification and characterization of a protein phosphatase (PP1-Arch) from the archaebacterium Sulfolobus solfataricus, isolation and expression of its gene

    Leng, Jie

    1994-01-01

    PP1-Arch was verified as a protein phosphatase by both acid molybdate extraction and thin layer electrophoresis. Soluble fraction was prepared from Sulfolobus solfataricus, from which PP1-Arch was purified over 1OOO-fold by DE-52 ion-exchange, hydroxyapatite, gel filtration (G- 100), and Mono Q FPLC chromatography. PP1-Arch was identified from the fmal purified sample by renaturation on an SDS-polyacrylamide gel. The molecular size of PP1-Arch was determined by both gel filtrat...

  12. Molecular Cloning, Structural Analysis and Tissue Expression of Protein Phosphatase 3 Catalytic Subunit Alpha Isoform (PPP3CA Gene in Tianfu Goat Muscle

    Lu Wan

    2014-02-01

    Full Text Available Calcineurin, a Ca2+/calmodulin-dependent protein phosphatase, plays a critical role in controlling skeletal muscle fiber type. However, little information is available concerning the expression of calcineurin in goat. Therefore, protein phosphatase 3 catalytic subunit alpha isoform (PPP3CA gene, also called calcineurin Aα, was cloned and its expression characterized in Tianfu goat muscle. Real time quantitative polymerase chain reaction (RT-qPCR analyses revealed that Tianfu goat PPP3CA was detected in cardiac muscle, biceps femoris muscle, abdominal muscle, longissimus dors muscle, and soleus muscle. High expression levels were found in biceps femoris muscle, longissimus muscle and abdominal muscle (p < 0.01, and low expression levels were seen in cardiac muscle and soleus muscle (p > 0.05. In addition, the spatial-temporal mRNA expression levels showed different variation trends in different muscles with the age of the goats. Western blotting further revealed that PPP3CA protein was expressed in the above-mentioned tissues, with the highest level in biceps femoris muscle, and the lowest level in soleus muscle. In this study, we isolated the full-length coding sequence of Tianfu goat PPP3CA gene, analyzed its structure, and investigated its expression in different muscle tissues from different age stages. These results provide a foundation for understanding the function of the PPP3CA gene in goats.

  13. Plasmin digestion of bovine $\\beta$-casein dephosphorylated with one protein phosphatase type 2A purified from Yarrowia lipolytica

    Jolivet, Pascale; Macedo, Isabel; Wu, Min; Meunier, Jean-Claude

    2000-01-01

    Hydrolyse par la plasmine de la caséine $\\beta$ bovine déphosphorylée par une protéine phosphatase de type 2A purifiée chez Yarrowia lipolytica. La caséine $\\beta$ peut être déphosphorylée par la sous-unité catalytique d'une protéine phosphatase de type 2A purifiée chez la levure Yarrowia lipolytica. La déphosphorylation complète est obtenue en 24 à 30 h en tampon Tris (pH 7.5). À l'inverse, elle est largement inhibée par le citrate de sodium 13 mmol$\\cdot$L$^{-1}$ à pH 6.8 (80 % d'inhibition...

  14. Cardiac sodium channel Na(v)1.5 interacts with and is regulated by the protein tyrosine phosphatase PTPH1.

    Jespersen, Thomas; Gavillet, Bruno; van Bemmelen, Miguel X; Cordonier, Sophie; Thomas, Marc A; Staub, Olivier; Abriel, Hugues

    2006-10-01

    In order to identify proteins interacting with the cardiac voltage-gated sodium channel Na(v)1.5, we used the last 66 amino acids of the C-terminus of the channel as bait to screen a human cardiac cDNA library. We identified the protein tyrosine phosphatase PTPH1 as an interacting protein. Pull-down experiments confirmed the interaction, and indicated that it depends on the PDZ-domain binding motif of Na(v)1.5. Co-expression experiments in HEK293 cells showed that PTPH1 shifts the Na(v)1.5 availability relationship toward hyperpolarized potentials, whereas an inactive PTPH1 or the tyrosine kinase Fyn does the opposite. The results of this study suggest that tyrosine phosphorylation destabilizes the inactivated state of Na(v)1.5. PMID:16930557

  15. Zelluläre Ko-Repressoren als funktionelle Interaktoren des Papillomvirus E8^E2C-Proteins

    Fertey, Jasmin

    2010-01-01

    Das E2 Gen von Papillomviren kodiert für mehrere Regulatorproteine, welche die Transkription und Replikation des viralen Genoms kontrollieren und somit die Expression der viralen Onkoproteine (E6/E7) modulieren. Da das E2 Gen häufig durch Integration in das Genom der Wirtszelle in Zervixkarzinomen deletiert ist, wurde postuliert, dass Störungen in der Onkogenexpression zur malignen Progression beitragen könnten. Neben dem vollständigen E2 Protein kodieren mehrere humane Papillomviren (HPV) fü...

  16. 5-HT(2C) serotonin receptor blockade prevents tau protein hyperphosphorylation and corrects the defect in hippocampal synaptic plasticity caused by a combination of environmental stressors in mice.

    Busceti, Carla Letizia; Di Pietro, Paola; Riozzi, Barbara; Traficante, Anna; Biagioni, Francesca; Nisticò, Robert; Fornai, Francesco; Battaglia, Giuseppe; Nicoletti, Ferdinando; Bruno, Valeria

    2015-09-01

    Exposure to multimodal sensory stressors is an everyday occurrence and sometimes becomes very intense, such as during rave parties or other recreational events. A growing body of evidence suggests that strong environmental stressors might cause neuronal dysfunction on their own in addition to their synergistic action with illicit drugs. Mice were exposed to a combination of physical and sensory stressors that are reminiscent of those encountered in a rave party. However, this is not a model of rave because it lacks the rewarding properties of rave. A 14-h exposure to environmental stressors caused an impairment of hippocampal long-term potentiation (LTP) and spatial memory, and an enhanced phosphorylation of tau protein in the CA1 and CA3 regions. These effects were transient and critically depended on the activation of 5-HT2C serotonin receptors, which are highly expressed in the CA1 region. Acute systemic injection of the selective 5-HT2C antagonist, RS-102,221 (2 mg/kg, i.p., 2 min prior the onset of stress), prevented tau hyperphosphorylation and also corrected the defects in hippocampal LTP and spatial memory. These findings suggest that passive exposure to a combination of physical and sensory stressors causes a reversible hippocampal dysfunction, which might compromise mechanisms of synaptic plasticity and spatial memory for a few days. Drugs that block 5-HT2C receptors might protect the hippocampus against the detrimental effect of environmental stressors. PMID:26145279

  17. Association of polymorphism of CYP2D6 and CYP2C9 genes encoding P-450 proteins of cytochrome with arterial hypertension

    Saratsev A.V.

    2012-12-01

    Full Text Available Gene polymorphisms of cytochrome P-450 CYP2 encoding proteins of cytochrome P-450 are essential forantihy-pertensive drugs metabolism. Purpose: We study the associations of functionally defective allele variants of CYP2D6 gene and CYP2C9 gene with the degree of arterial hypertension (AH. Materials and methods: Samples of DNA of leukocytes of blood of 150 patients with AH without the associated clinical conditions (56% of women at the age of 20-59 years have been investigated. For the study of polymorphism of genes the pharmacogenetic biochip developed in the Institute of Molecular Biology n.a. V. A. Engelgardt has been used. Comparison of frequencies of occurrence of signs has been carried out on the basis of chi-square criterion. Results: It has been revealed that homozygotes by mutant A1075C, C430T alleles of CYP2C9gene and G1934A of CYP2D6 gene have been significantly more common among patients with hypertension III (p=0.01. Conclusion: The research works on genes of system of P-450 cytochrome have important clinical value for rationalization of pharmacotherapy of hypertension. The increased frequency of occurrence of mutant allele of CYP2D6 and CYP2C9 genes in patients with hypertension III requires special attention to the problem of efficiency and safety of application of hypotensive drugs for the patients.

  18. Inhibition of the Secretory pathway by Foot-and-Mouth disease virus 2BC protein is reproduced by co-expression of 2B with 2C, and the site of inhibition is determined by the subcellular location of 2C

    Moffat, Katy; Knox, Caroline; Howell, Gareth;

    2007-01-01

    immune responses in vivo. Foot-and-mouth disease virus (FMDV), another picornavirus, can cause persistent infection of ruminants, suggesting it too may inhibit immune responses. Endoplasmic reticulum (ER)-to-Golgi apparatus transport of proteins is blocked by the FMDV 2BC protein. The observation that 2...... blocked in FMDV-infected cells. The block could be reconstituted by coexpression of 2B and 2C, showing that processing of 2BC did not compromise the ability of FMDV to slow secretion. Under these conditions, 2C was located to the Golgi apparatus, and the block in transport also occurred in the Golgi...... apparatus. Interestingly, the block in transport could be redirected to the ER when 2B was coexpressed with a 2C protein fused to an ER retention element. Thus, for FMDV a block in secretion is dependent on both 2B and 2C, with the latter determining the site of the block....

  19. Blocking protein phosphatase 2A signaling prevents endothelial-to-mesenchymal transition and renal fibrosis: a peptide-based drug therapy

    Deng, Yuanjun; Guo, Yanyan; Liu, Ping; Zeng, Rui; Ning, Yong; Pei, Guangchang; Li, Yueqiang; Chen, Meixue; Guo, Shuiming; Li, Xiaoqing; Han, Min; Xu, Gang

    2016-01-01

    Endothelial-to-mesenchymal transition (EndMT) contributes to the emergence of fibroblasts and plays a significant role in renal interstitial fibrosis. Protein phosphatase 2A (PP2A) is a major serine/threonine protein phosphatase in eukaryotic cells and regulates many signaling pathways. However, the significance of PP2A in EndMT is poorly understood. In present study, the role of PP2A in EndMT was evaluated. We demonstrated that PP2A activated in endothelial cells (EC) during their EndMT phenotype acquisition and in the mouse model of obstructive nephropathy (i.e., UUO). Inhibition of PP2A activity by its specific inhibitor prevented EC undergoing EndMT. Importantly, PP2A activation was dependent on tyrosine nitration at 127 in the catalytic subunit of PP2A (PP2Ac). Our renal-protective strategy was to block tyrosine127 nitration to inhibit PP2A activation by using a mimic peptide derived from PP2Ac conjugating a cell penetrating peptide (CPP: TAT), termed TAT-Y127WT. Pretreatment withTAT-Y127WT was able to prevent TGF-β1-induced EndMT. Administration of the peptide to UUO mice significantly ameliorated renal EndMT level, with preserved density of peritubular capillaries and reduction in extracellular matrix deposition. Taken together, these results suggest that inhibiting PP2Ac nitration using a mimic peptide is a potential preventive strategy for EndMT in renal fibrosis.

  20. Profile of serum alkaline phosphatase after inoculation of mononuclear cells and bone morphogenetic protein in the repair of osteochondral defects in rabbits

    Luiz Augusto de Souza

    2011-12-01

    Full Text Available In this study, serum alkaline phosphatase activity was measured in response to the repair of osteochondral defects in twenty-four New Zealand rabbits. The animals were divided into three groups: a control (GC, those treated with bone marrow mononuclear cells (GCM and those that received mononuclear cells with autologous bone morphogenetic protein (BMP + GCM. After exposing the trochlear groove of the left stifle joint, a wedge-shaped segment was removed. Later, the defect was filled with an osteochondral autograft preserved in 98% glycerin. For the GC group, only the bone graft was performed. For the GCM, in addition to the graft, 2x106 seed mononuclear cells were implanted. For the GCM + BMP, the same number of cells, associated with 1μg of bone morphogenetic protein, were intraarticularly administered. The osteoblastic response was measured by analyzing the serum alkaline phosphatase on day 0 (preoperative 3, 15, 30, and 45 after surgery, and by radiographic examinations. Analysis of variance in randomized blocks, factorial and Tukey’s test (p = 0.05 were made. The overall mean GCM was superior to the other groups and the highest rates were among the 15th and 45th days postoperatively. The discrepancy in values between individuals of the same group casts doubts on the veracity of the test.

  1. VPS29 is not an active metallo-phosphatase but is a rigid scaffold required for retromer interaction with accessory proteins.

    James D Swarbrick

    Full Text Available VPS29 is a key component of the cargo-binding core complex of retromer, a protein assembly with diverse roles in transport of receptors within the endosomal system. VPS29 has a fold related to metal-binding phosphatases and mediates interactions between retromer and other regulatory proteins. In this study we examine the functional interactions of mammalian VPS29, using X-ray crystallography and NMR spectroscopy. We find that although VPS29 can coordinate metal ions Mn(2+ and Zn(2+ in both the putative active site and at other locations, the affinity for metals is low, and lack of activity in phosphatase assays using a putative peptide substrate support the conclusion that VPS29 is not a functional metalloenzyme. There is evidence that structural elements of VPS29 critical for binding the retromer subunit VPS35 may undergo both metal-dependent and independent conformational changes regulating complex formation, however studies using ITC and NMR residual dipolar coupling (RDC measurements show that this is not the case. Finally, NMR chemical shift mapping indicates that VPS29 is able to associate with SNX1 via a conserved hydrophobic surface, but with a low affinity that suggests additional interactions will be required to stabilise the complex in vivo. Our conclusion is that VPS29 is a metal ion-independent, rigid scaffolding domain, which is essential but not sufficient for incorporation of retromer into functional endosomal transport assemblies.

  2. Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

    Boylan, Joan M. [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Salomon, Arthur R. [Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States); Department of Chemistry, Brown University, Providence, RI (United States); Tantravahi, Umadevi [Division of Genetics, Department of Pathology, Brown University and Women and Infants Hospital, Providence, RI (United States); Gruppuso, Philip A., E-mail: philip_gruppuso@brown.edu [Department of Pediatrics, Brown University and Rhode Island Hospital, Providence, RI (United States); Department of Molecular Biology, Cell Biology and Biochemistry, Brown University, Providence, RI (United States)

    2015-07-15

    Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders. - Highlights: • Lentiviral-transduced shRNA was used to generate a stable knockdown of PP6 in HepG2 cells. • Cells adapted to reduced PP6; cell proliferation was unaffected, and cell survival was normal. • However, PP6 knockdown was associated with a transition to a tetraploid state. • Genomic profiling showed downregulated anti-inflammatory signaling and DNA replication. • Phosphoproteomic profiling showed changes in proteins associated with DNA replication and repair.

  3. Adaptation of HepG2 cells to a steady-state reduction in the content of protein phosphatase 6 (PP6) catalytic subunit

    Protein phosphatase 6 (PP6) is a ubiquitous Ser/Thr phosphatase involved in an array of cellular processes. To assess the potential of PP6 as a therapeutic target in liver disorders, we attenuated expression of the PP6 catalytic subunit in HepG2 cells using lentiviral-transduced shRNA. Two PP6 knock-down (PP6KD) cell lines (90% reduction of PP6-C protein content) were studied in depth. Both proliferated at a rate similar to control cells. However, flow cytometry indicated G2/M cell cycle arrest that was accounted for by a shift of the cells from a diploid to tetraploid state. PP6KD cells did not show an increase in apoptosis, nor did they exhibit reduced viability in the presence of bleomycin or taxol. Gene expression analysis by microarray showed attenuated anti-inflammatory signaling. Genes associated with DNA replication were downregulated. Mass spectrometry-based phosphoproteomic analysis yielded 80 phosphopeptides representing 56 proteins that were significantly affected by a stable reduction in PP6-C. Proteins involved in DNA replication, DNA damage repair and pre-mRNA splicing were overrepresented among these. PP6KD cells showed intact mTOR signaling. Our studies demonstrated involvement of PP6 in a diverse set of biological pathways and an adaptive response that may limit the effectiveness of targeting PP6 in liver disorders. - Highlights: • Lentiviral-transduced shRNA was used to generate a stable knockdown of PP6 in HepG2 cells. • Cells adapted to reduced PP6; cell proliferation was unaffected, and cell survival was normal. • However, PP6 knockdown was associated with a transition to a tetraploid state. • Genomic profiling showed downregulated anti-inflammatory signaling and DNA replication. • Phosphoproteomic profiling showed changes in proteins associated with DNA replication and repair

  4. Mutational analysis of the coding regions of the genes encoding protein kinase B-alpha and -beta, phosphoinositide-dependent protein kinase-1, phosphatase targeting to glycogen, protein phosphatase inhibitor-1, and glycogenin

    Hansen, L; Fjordvang, H; Rasmussen, S K;

    1999-01-01

    might be caused by genetic variability in the genes encoding proteins shown by biochemical evidence to be involved in insulin-stimulated glycogen synthesis in skeletal muscle. In 70 insulin-resistant Danish NIDDM patients, mutational analysis by reverse transcription-polymerase chain reaction...... a genetic involvement in the disease. The mode of inheritance of the common forms of NIDDM is as yet unclear, but the prevailing hypothesis supports a polygenic model. In the present study, we tested the hypothesis that the putative inheritable defects of insulin-stimulated muscle glycogen synthesis...

  5. Regulation of Cys-based protein tyrosine phosphatases via reactive oxygen and nitrogen species in mast cells and basophils

    Heneberg, Petr; Dráber, Petr

    2005-01-01

    Roč. 12, č. 16 (2005), s. 1859-1871. ISSN 0929-8673 R&D Projects: GA ČR(CZ) GA204/03/0594; GA ČR(CZ) GA301/03/0596; GA AV ČR(CZ) IAA5052310; GA MZd(CZ) NR8079; GA MŠk(CZ) 1M0506; GA MŠk(CZ) 1P04OE158 Institutional research plan: CEZ:AV0Z50520514 Keywords : mast cell * tyrosine phosphatase * reactive oxygen species Subject RIV: EB - Genetics ; Molecular Biology Impact factor: 4.904, year: 2005

  6. Comparison of measurements of canine plasma creatinine, glucose, proteins, urea, alanine aminotransferase, and alkaline phosphatase obtained with Spotchem SP 4430 and Vitros 250 analyzers.

    Trumel, C; Diquélou, A; Germain, C; Palanché, F; Braun, J P

    2005-12-01

    The suitability of the Spotchem 4430 benchtop biochemistry analyzer for canine blood samples was tested for creatinine, glucose, proteins, urea, alkaline phosphatases and alanine aminotransferase. Results obtained from whole blood and corresponding heparin plasma were identical except for proteins which were higher in plasma (n=10). Between series imprecision (n=10) was 0.93). The slopes of the Passing-Bablock's regression ranged from 0.90 to 1.20 and intercepts were low. The mean biases were low, except for creatinine for which the results obtained by Spotchem (Jaffe reaction) were about 20 micromol/L higher than with the Vitros (enzymatic reaction). The results of this study show that the Spotchem analyzer is suitable for use in canine whole blood or plasma when small numbers of tests are to be performed and large analyzers are not available. PMID:16054888

  7. Phosphatase of Regenerating Liver and Its Association with Tumors

    Yuqiong Liu; Huixiang Li

    2007-01-01

    @@ INTRODUCTION Protein kinases and protein phosphatases play key roles in regulating functions of diverse proteins which control numerous essential events in eukaryotes, such as transcriptional regulation, apoptosis, cell cycle progression, protein degradation and protein trafficking[1-3].

  8. Structural and biochemical characterization of human PR70 in isolation and in complex with the scaffolding subunit of protein phosphatase 2A.

    Rebecca Dovega

    Full Text Available Protein Phosphatase 2A (PP2A is a major Ser/Thr phosphatase involved in the regulation of various cellular processes. PP2A assembles into diverse trimeric holoenzymes, which consist of a scaffolding (A subunit, a catalytic (C subunit and various regulatory (B subunits. Here we report a 2.0 Å crystal structure of the free B''/PR70 subunit and a SAXS model of an A/PR70 complex. The crystal structure of B''/PR70 reveals a two domain elongated structure with two Ca2+ binding EF-hands. Furthermore, we have characterized the interaction of both binding partner and their calcium dependency using biophysical techniques. Ca2+ biophysical studies with Circular Dichroism showed that the two EF-hands display different affinities to Ca2+. In the absence of the catalytic C-subunit, the scaffolding A-subunit remains highly mobile and flexible even in the presence of the B''/PR70 subunit as judged by SAXS. Isothermal Titration Calorimetry studies and SAXS data support that PR70 and the A-subunit have high affinity to each other. This study provides additional knowledge about the structural basis for the function of B'' containing holoenzymes.

  9. Down-regulated expression of the protein-tyrosine phosphatase 1B (PTP1B) is associated with aggressive clinicopathologic features and poor prognosis in hepatocellular carcinoma

    Highlights: ► PTP1B protein showed decreased expression in 67.79% of the HCC patients. ► Low PTP1B expression predicts poor prognosis of HCC. ► Low PTP1B expression is correlated with expansion of OV6+ tumor-initiating cells. ► Down-regulation of PTP1B is associated with activation of Wnt/β-Catenin signaling. -- Abstract: The protein-tyrosine phosphatase 1B (PTP1B) is a classical non-transmembrane protein tyrosine phosphatase that plays a key role in metabolic signaling and can exert both tumor suppressing and tumor promoting effects in different cancers depending on the substrate involved and the cellular context. However, the expression level and function of PTP1B in hepatocellular carcinoma (HCC) remain unclear. In this study, PTP1B expression was detected by immunohistochemistry in normal liver tissue (n = 16) and hepatocellular carcinoma (n = 169). The correlations between PTP1B expression level and clinicopathologic features and patient survival were also analyzed. One hundred and eleven of 169 HCC patients (65.7%) had negative or low PTP1B expression in tumorous tissues, whereas normal tissues always expressed strong PTP1B. Decreased PTP1B expression was significantly associated with aggressive clinicopathologic features and poor prognosis. Immunohistochemistry also showed that low PTP1B expression level was correlated with high percentage of OV6+ tumor-initiating cells (T-ICs) and high frequency of nuclear β-Catenin expression in HCC specimens. Our findings demonstrate for the first time that the loss of inhibitory effect of PTP1B may contribute to progression and invasion of HCC through activation of Wnt/β-Catenin signaling and expansion of liver T-ICs. PTP1B may serve as a valuable prognostic biomarker and potential therapeutic target in HCC.

  10. A protein phosphatase 1 gamma (PP1γ) of the human protozoan parasite Trichomonas vaginalis is involved in proliferation and cell attachment to the host cell.

    Muñoz, Christian; Pérez, Mauricio; Orrego, Patricio R; Osorio, Luis; Gutiérrez, Bessy; Sagua, Hernán; Castillo, Juan L; Martínez-Oyanedel, Jose; Arroyo, Rossana; Meza-Cervantez, Patricia; da Silveira, Jose Franco; Midlej, Victor; Benchimol, Marlene; Cordero, Esteban; Morales, Patricio; Araya, Jorge E; González, Jorge

    2012-07-01

    In this work, evidence for a critical role of Trichomonas vaginalis protein phosphatase 1 gamma (TvPP1γ) in proliferation and attachment of the parasite to the mammalian cell is provided. Firstly, proliferation and attachment of T. vaginalis parasites to HeLa cells was blocked by calyculin A (CA), a potent PP1 inhibitor. Secondly, it was demonstrated that the enzyme activity of native and recombinant TvPP1γ proteins was inhibited by CA. Thirdly, reverse genetic studies confirmed that antisense oligonucleotides targeted to PP1γ but not PP1α or β inhibited proliferation and attachment of trichomonads CA-treated parasites underwent cytoskeletal modifications, including a lack of axostyle typical labelling, suggesting that cytoskeletal phosphorylation could be regulated by a CA-sensitive phosphatase where the role of PP1γ could not be ruled out. Analysis of subcellular distribution of TvPP1γ by cell fractionation and electron microscopy demonstrated the association between TvPP1γ and the cytoskeleton. The expression of adhesins, AP120 and AP65, at the cell surface was also inhibited by CA. The concomitant inhibition of expression of adhesins and changes in the cytoskeleton in CA-treated parasites suggest a specific role for PP1γ -dependent dephosphorylation in the early stages of the host-parasite interaction. Molecular modelling of TvPP1γ showed the conservation of residues critical for maintaining proper folding into the gross structure common to PP1 proteins. Taken together, these results suggest that TvPP1γ could be considered a potential novel drug target for treatment of trichomoniasis. PMID:22713760

  11. A novel strategy for the development of selective active-site inhibitors of the protein tyrosine phosphatase-like proteins islet-cell antigen 512 (IA-2) and phogrin (IA-2 beta)

    Drake, P.G.; Peters, Günther H.j.; Andersen, H.S.;

    2003-01-01

    Islet-cell antigen 512 (IA-2) and phogrin (IA-2) are atypical members of he receptor protein tyrosine phosphatase (PTP) family that are characterized by a lack of activity against conventional PTP substrates. The physiological role(s) of these proteins remain poorly defined, although recent studies...... indicate that IA-2 may be involved in granule trafficking and exocytosis. To further 9 understand their function, we have embarked upon developing low-molecular-mass inhibitors of IA-2 and IA-2. Previously, we have shown that a general PTP inhibitor, 2-(oxalylamino)benzoic acid (OBA), can be developed into...

  12. RPM-1 uses both ubiquitin ligase and phosphatase-based mechanisms to regulate DLK-1 during neuronal development.

    Scott T Baker

    2014-05-01

    Full Text Available The Pam/Highwire/RPM-1 (PHR proteins are key regulators of neuronal development that function in axon extension and guidance, termination of axon outgrowth, and synapse formation. Outside of development, the PHR proteins also regulate axon regeneration and Wallerian degeneration. The PHR proteins function in part by acting as ubiquitin ligases that degrade the Dual Leucine zipper-bearing Kinase (DLK. Here, we show that the Caenorhabditis elegans PHR protein, Regulator of Presynaptic Morphology 1 (RPM-1, also utilizes a phosphatase-based mechanism to regulate DLK-1. Using mass spectrometry, we identified Protein Phosphatase Magnesium/Manganese dependent 2 (PPM-2 as a novel RPM-1 binding protein. Genetic, transgenic, and biochemical studies indicated that PPM-2 functions coordinately with the ubiquitin ligase activity of RPM-1 and the F-box protein FSN-1 to negatively regulate DLK-1. PPM-2 acts on S874 of DLK-1, a residue implicated in regulation of DLK-1 binding to a short, inhibitory isoform of DLK-1 (DLK-1S. Our study demonstrates that PHR proteins function through both phosphatase and ubiquitin ligase mechanisms to inhibit DLK. Thus, PHR proteins are potentially more accurate and sensitive regulators of DLK than originally thought. Our results also highlight an important and expanding role for the PP2C phosphatase family in neuronal development.

  13. Microcystin-LR induces mitotic spindle assembly disorders in Vicia faba by protein phosphatase inhibition and not reactive oxygen species induction.

    Garda, Tamás; Kónya, Zoltán; Tándor, Ildikó; Beyer, Dániel; Vasas, Gábor; Erdődi, Ferenc; Vereb, György; Papp, Georgina; Riba, Milán; M-Hamvas, Márta; Máthé, Csaba

    2016-07-20

    We aimed to reveal the mechanisms of mitotic spindle anomalies induced by microcystin-LR (MCY-LR), a cyanobacterial toxin in Vicia faba, a well-known model in plant cell and molecular biology. MCY-LR inhibits type 1 and 2A phosphoserine/threonine specific protein phosphatases (PP1 and PP2A) and induces reactive oxygen species (ROS) formation. The cytoskeleton is one of the main targets of the cyanotoxin during cytopathogenesis. Histochemical-immunohistochemical and biochemical methods were used. A significant number of MCY-LR induced spindle alterations are described for the first time. Disrupted, multipolar spindles and missing kinetochore fibers were detected both in metaphase and anaphase cells. Additional polar microtubule (MT) bundles, hyperbundling of spindle MTs, monopolar spindles, C-S- shaped, additional and asymmetric spindles were detected in metaphase, while midplane kinetochore fibers were detected in anaphase cells only. Several spindle anomalies induced mitotic disorders, i.e. they occurred concomitantly with altered sister chromatid separation. Alterations were dependent on the MCY-LR dose and exposure time. Under long-term (2 and mainly 6 days') exposure they were detected in the concentration range of 0.1-20μgmL(-1) MCY-LR that inhibited PP1 and PP2A significantly without significant ROS induction. Elevated peroxidase/catalase activities indicated that MCY-LR treated V. faba plants showed efficient defense against oxidative stress. Thus, although the elevation of ROS is known to induce cytoskeletal aberrations in general, this study shows that long-term protein phosphatase inhibition is the primary cause of MCY-LR induced spindle disorders. PMID:27186862

  14. Retromer in Osteoblasts Interacts With Protein Phosphatase 1 Regulator Subunit 14C, Terminates Parathyroid Hormone's Signaling, and Promotes Its Catabolic Response.

    Xiong, Lei; Xia, Wen-Fang; Tang, Fu-Lei; Pan, Jin-Xiu; Mei, Lin; Xiong, Wen-Cheng

    2016-07-01

    Parathyroid hormone (PTH) plays critical, but distinct, roles in bone remodeling, including bone formation (anabolic response) and resorption (catabolic response). Although its signaling and function have been extensively investigated, it just began to be understood how distinct functions are induced by PTH activating a common receptor, the PTH type 1 receptor (PTH1R), and how PTH1R signaling is terminated. Here, we provide evidence for vacuolar protein sorting 35 (VPS35), a major component of retromer, in regulating PTH1R trafficking, turning off PTH signaling, and promoting its catabolic function. VPS35 is expressed in osteoblast (OB)-lineage cells. VPS35-deficiency in OBs impaired PTH(1-34)-promoted PTH1R translocation to the trans-Golgi network, enhanced PTH(1-34)-driven signaling, and reduced PTH(1-34)'s catabolic response in culture and in mice. Further mechanical studies revealed that VPS35 interacts with not only PTH1R, but also protein phosphatase 1 regulatory subunit 14C (PPP1R14C), an inhibitory subunit of PP1 phosphatase. PPP1R14C also interacts with PTH1R, which is necessary for the increased endosomal PTH1R signaling and decreased PTH(1-34)'s catabolic response in VPS35-deficient OB-lineage cells. Taken together, these results suggest that VPS35 deregulates PTH1R-signaling likely by its interaction with PTH1R and PPP1R14C. This event is critical for the control of PTH(1-34)-signaling dynamics, which may underlie PTH-induced catabolic response and adequate bone remodeling. PMID:27333042

  15. ALP (Alkaline Phosphatase) Test

    ... Also known as: ALK PHOS; Alkp Formal name: Alkaline Phosphatase Related tests: AST ; ALT ; GGT ; Bilirubin ; Liver Panel ; Bone Markers ; Alkaline Phosphatase Isoenzymes; Bone Specific ALP All content on ...

  16. Production and characterization of a single-chain variable fragment linked alkaline phosphatase fusion protein for detection of O,O-diethyl organophosphorus pesticides in a one-step enzyme-linked immunosorbent assay

    A single-chain variable fragment (scFv) and alkaline phosphatase (AP) fusion protein for detection of O, O-diethyl organophosphorus pesticides (OPs) was produced and characterized. The scFv gene was prepared by cloning VL and VH genes from a hybridoma cell secreting monoclonal antibody with broad-s...

  17. Investigation of the vitamin D receptor gene (VDR) and its interaction with protein tyrosine phosphatase, non-receptor type 2 gene (PTPN2) on risk of islet autoimmunity and type 1 diabetes : The Diabetes Autoimmunity Study in the Young (DAISY)

    Frederiksen, B.; Liu, E.; Romanos, J.; Steck, A. K.; Yin, X.; Kroehl, M.; Fingerlin, T. E.; Erlich, H.; Eisenbarth, G. S.; Rewers, M.; Norris, J. M.

    2013-01-01

    The present study investigated the association between variants in the vitamin D receptor gene (VDR) and protein tyrosine phosphatase, non-receptor type 2 gene (PTPN2), as well as an interaction between VDR and PTPN2 and the risk of islet autoimmunity (IA) and progression to type 1 diabetes (T1D). T

  18. The human cytomegalovirus UL11 protein interacts with the receptor tyrosine phosphatase CD45, resulting in functional paralysis of T cells.

    Ildar Gabaev

    2011-12-01

    Full Text Available Human cytomegalovirus (CMV exerts diverse and complex effects on the immune system, not all of which have been attributed to viral genes. Acute CMV infection results in transient restrictions in T cell proliferative ability, which can impair the control of the virus and increase the risk of secondary infections in patients with weakened or immature immune systems. In a search for new immunomodulatory proteins, we investigated the UL11 protein, a member of the CMV RL11 family. This protein family is defined by the RL11 domain, which has homology to immunoglobulin domains and adenoviral immunomodulatory proteins. We show that pUL11 is expressed on the cell surface and induces intercellular interactions with leukocytes. This was demonstrated to be due to the interaction of pUL11 with the receptor tyrosine phosphatase CD45, identified by mass spectrometry analysis of pUL11-associated proteins. CD45 expression is sufficient to mediate the interaction with pUL11 and is required for pUL11 binding to T cells, indicating that pUL11 is a specific CD45 ligand. CD45 has a pivotal function regulating T cell signaling thresholds; in its absence, the Src family kinase Lck is inactive and signaling through the T cell receptor (TCR is therefore shut off. In the presence of pUL11, several CD45-mediated functions were inhibited. The induction of tyrosine phosphorylation of multiple signaling proteins upon TCR stimulation was reduced and T cell proliferation was impaired. We therefore conclude that pUL11 has immunosuppressive properties, and that disruption of T cell function via inhibition of CD45 is a previously unknown immunomodulatory strategy of CMV.

  19. Progestin-inducible EDD E3 ubiquitin ligase binds to α4 phosphoprotein to regulate ubiquitination and degradation of protein phosphatase PP2Ac.

    McDonald, William J; Thomas, Lynn N; Koirala, Samir; Too, Catherine K L

    2014-01-25

    Mammalian α4 phosphoprotein binds to the protein phosphatase 2A catalytic subunit (PP2Ac) to regulate PP2A activity, and to poly(A)-binding protein (PABP) and progestin-inducible EDD E3 ubiquitin ligase. This study showed induction of the EDD protein by progesterone, 17β-estradiol and prolactin in breast cancer cells. Co-immunoprecipitation analyses, using lysates of COS-1 cells transfected with α4-deletion constructs, showed the α4 N-terminus binding to endogenous PP2Ac and PABP, and the C-terminus to EDD. Monoubiquitinated α4 in MCF-7 cells was unaffected by EDD-targeting siRNA (siEDD) nor by non-targetting siNT, thus, EDD does not ubiquitinate α4. PP2Ac is polyubiquitinated, and 36-kDa PP2Ac only was detected in siEDD- or siNT-transfected cells. However, treatment with proteasomal inhibitor MG132 showed polyubiquitinated-PP2Ac molecules (∼65-250kDa) abundantly in siNT controls but low in siEDD-transfectants, implicating PP2Ac as an EDD substrate. Finally, progesterone induction of EDD in MCF-7 cells correlated with decreased PP2Ac levels, further implicating hormone-inducible EDD in PP2Ac turnover. PMID:24145130

  20. Crystal structures and mutagenesis of PPP-family ser/thr protein phosphatases elucidate the selectivity of cantharidin and novel norcantharidin-based inhibitors of PP5C.

    Chattopadhyay, Debasish; Swingle, Mark R; Salter, Edward A; Wood, Eric; D'Arcy, Brandon; Zivanov, Catherine; Abney, Kevin; Musiyenko, Alla; Rusin, Scott F; Kettenbach, Arminja; Yet, Larry; Schroeder, Chad E; Golden, Jennifer E; Dunham, Wade H; Gingras, Anne-Claude; Banerjee, Surajit; Forbes, David; Wierzbicki, Andrzej; Honkanen, Richard E

    2016-06-01

    Cantharidin is a natural toxin and an active constituent in a traditional Chinese medicine used to treat tumors. Cantharidin acts as a semi-selective inhibitor of PPP-family ser/thr protein phosphatases. Despite sharing a common catalytic mechanism and marked structural similarity with PP1C, PP2AC and PP5C, human PP4C was found to be insensitive to the inhibitory activity of cantharidin. To explore the molecular basis for this selectivity, we synthesized and tested novel C5/C6-derivatives designed from quantum-based modeling of the interactions revealed in the co-crystal structures of PP5C in complex with cantharidin. Structure-activity relationship studies and analysis of high-resolution (1.25Å) PP5C-inhibitor co-crystal structures reveal close contacts between the inhibitor bridgehead oxygen and both a catalytic metal ion and a non-catalytic phenylalanine residue, the latter of which is substituted by tryptophan in PP4C. Quantum chemistry calculations predicted that steric clashes with the bulkier tryptophan side chain in PP4C would force all cantharidin-based inhibitors into an unfavorable binding mode, disrupting the strong coordination of active site metal ions observed in the PP5C co-crystal structures, thereby rendering PP4C insensitive to the inhibitors. This prediction was confirmed by inhibition studies employing native human PP4C. Mutation of PP5C (F446W) and PP1C (F257W), to mimic the PP4C active site, resulted in markedly suppressed sensitivity to cantharidin. These observations provide insight into the structural basis for the natural selectivity of cantharidin and provide an avenue for PP4C deselection. The novel crystal structures also provide insight into interactions that provide increased selectivity of the C5/C6 modifications for PP5C versus other PPP-family phosphatases. PMID:27002182

  1. Structure-Function Analysis of PPP1R3D, a Protein Phosphatase 1 Targeting Subunit, Reveals a Binding Motif for 14-3-3 Proteins which Regulates its Glycogenic Properties.

    Carla Rubio-Villena

    Full Text Available Protein phosphatase 1 (PP1 is one of the major protein phosphatases in eukaryotic cells. It plays a key role in regulating glycogen synthesis, by dephosphorylating crucial enzymes involved in glycogen homeostasis such as glycogen synthase (GS and glycogen phosphorylase (GP. To play this role, PP1 binds to specific glycogen targeting subunits that, on one hand recognize the substrates to be dephosphorylated and on the other hand recruit PP1 to glycogen particles. In this work we have analyzed the functionality of the different protein binding domains of one of these glycogen targeting subunits, namely PPP1R3D (R6 and studied how binding properties of different domains affect its glycogenic properties. We have found that the PP1 binding domain of R6 comprises a conserved RVXF motif (R102VRF located at the N-terminus of the protein. We have also identified a region located at the C-terminus of R6 (W267DNND that is involved in binding to the PP1 glycogenic substrates. Our results indicate that although binding to PP1 and glycogenic substrates are independent processes, impairment of any of them results in lack of glycogenic activity of R6. In addition, we have characterized a novel site of regulation in R6 that is involved in binding to 14-3-3 proteins (RARS74LP. We present evidence indicating that when binding of R6 to 14-3-3 proteins is prevented, R6 displays hyper-glycogenic activity although is rapidly degraded by the lysosomal pathway. These results define binding to 14-3-3 proteins as an additional pathway in the control of the glycogenic properties of R6.

  2. Theoretical models of catalytic domains of protein phosphatases 1 and 2A with Zn2+ and Mn2+ metal dications and putative bioligands in their catalytic centers.

    Woźniak-Celmer, E; Ołdziej, S; Ciarkowski, J

    2001-01-01

    The oligomeric metalloenzymes protein phosphatases dephosphorylate OH groups of Ser/Thr or Tyr residues of proteins whose actions depend on the phosphorus signal. The catalytic units of Ser/Thr protein phosphatases 1, 2A and 2B (PP1c, PP2Ac and PP2Bc, respectively), which exhibit about 45% sequence similarity, have their active centers practically identical. This feature strongly suggests that the unknown structure of PP2Ac could be successfully homology-modeled from the known structures of PP1c and/or PP2Bc. Initially, a theoretical model of PP1c was built, including a phosphate and a metal dication in its catalytic site. The latter was modeled, together with a structural hydroxyl anion, as a triangular pseudo-molecule (Zno or Mno), composed of two metal cations (double Zn2+ or Mn2+, respectively) and the OH- group. To the free PP1c two inhibitor sequences R29RRRPpTPAMLFR40 of DARPP-32 and R30RRRPpTPATLVLT42 of Inhibitor-1, and two putative substrate sequences LRRApSVA and QRRQRKpRRTI were subsequently docked. In the next step, a free PP2Ac model was built via homology re-modeling of the PP1c template and the same four sequences were docked to it. Thus, together, 20 starting model complexes were built, allowing for combination of the Zno and Mno pseudo-molecules, free enzymes and the peptide ligands docked in the catalytic sites of PP1c and PP2Ac. All models were subsequently subjected to 250-300 ps molecular dynamics using the AMBER 5.0 program. The equilibrated trajectories of the final 50 ps were taken for further analyses. The theoretical models of PP1c complexes, irrespective of the dication type, exhibited increased mobilities in the following residue ranges: 195-200, 273-278, 287-209 for the inhibitor sequences and 21-25, 194-200, 222-227, 261, 299-302 for the substrate sequences. Paradoxically, the analogous PP2Ac models appeared much more stable in similar simulations, since only their "prosegment" residues 6-10 and 14-18 exhibited an increased mobility

  3. Rapid activation of the T-cell tyrosine protein kinase pp56lck by the CD45 phosphotyrosine phosphatase.

    Mustelin, T; Coggeshall, K M; Altman, A

    1989-01-01

    T lymphocytes express a tyrosine protein kinase (TPK; protein-tyrosine kinase; ATP:protein-tyrosine O-phosphotransferase, EC 2.7.1.112), pp56lck that is encoded by the lck protooncogene. This TPK was recently found to be associated with the intracellular domain of the T-cell surface glycoproteins, CD4 and CD8, suggesting that it plays an important role in T-cell development and activation. We have studied the regulation of pp56lck and found that this kinase can be rapidly activated by an endo...

  4. Cinnamon extract enhances glucose uptake in 3T3-L1 adipocytes and C2C12 myocytes by inducing LKB1-AMP-activated protein kinase signaling.

    Yan Shen

    Full Text Available We previously demonstrated that cinnamon extract (CE ameliorates type 1 diabetes induced by streptozotocin in rats through the up-regulation of glucose transporter 4 (GLUT4 translocation in both muscle and adipose tissues. This present study was aimed at clarifying the detailed mechanism(s with which CE increases the glucose uptake in vivo and in cell culture systems using 3T3-L1 adipocytes and C2C12 myotubes in vitro. Specific inhibitors of key enzymes in insulin signaling and AMP-activated protein kinase (AMPK signaling pathways, as well as small interference RNA, were used to examine the role of these kinases in the CE-induced glucose uptake. The results showed that CE stimulated the phosphorylation of AMPK and acetyl-CoA carboxylase. An AMPK inhibitor and LKB1 siRNA blocked the CE-induced glucose uptake. We also found for the first time that insulin suppressed AMPK activation in the adipocyte. To investigate the effect of CE on type 2 diabetes in vivo, we further performed oral glucose tolerance tests and insulin tolerance tests in type 2 diabetes model rats administered with CE. The CE improved glucose tolerance in oral glucose tolerance tests, but not insulin sensitivity in insulin tolerance test. In summary, these results indicate that CE ameliorates type 2 diabetes by inducing GLUT4 translocation via the AMPK signaling pathway. We also found insulin antagonistically regulates the activation of AMPK.

  5. Interleukin 2 induces a transient downregulation of protein phosphatase 1 and 2A activity in human T cells

    Brockdorff, J; Nielsen, M; Dobson, P; Geisler, C; Röpke, C; Svejgaard, A; Odum, N

    Stimulation of human CD4+ T cell lines with interleukin 2 (IL-2) induces tyrosine, serine and threonine phosphorylation of a series of proteins involved in the IL-2 receptor (IL-2R) signaling pathway. Here, we examined whether IL-2 induces changes in the activity of protein serine/threonine phosp......Stimulation of human CD4+ T cell lines with interleukin 2 (IL-2) induces tyrosine, serine and threonine phosphorylation of a series of proteins involved in the IL-2 receptor (IL-2R) signaling pathway. Here, we examined whether IL-2 induces changes in the activity of protein serine...... activity (p < 0.0005, n = 17) and a seven percent decrease in PP1 activity (p < 0.00005, n = 17). Cytokine-induced downregulation of PP2A activity reaches a maximum 60 min after IL-2R ligation, and returns to baseline levels within two hours. Downregulation of PPI activity reaches a maximum after 30 min...

  6. Protein tyrosine phosphatases involved in signaling of the ABA-induced H2O2generation in guard cells of Vicia faba L.

    SHI Wuliang; JlA Wensuo; LIU Xin; ZHANG Shuqiu

    2004-01-01

    Although protein tyrosine phosphatases (PTPases) play an important role in signal transduction in animal cells, little is known about the function of PTPases in higher plants. Hydrogen peroxide (H2O2) and mitogen-activated protein kinases (MAPKs) are the critical components of ABA signaling pathway in guard cells. PTPase is an important regulator of MAPK, which is believed to mediate ABA-induced H2O2 generation in guard cells of Viciafaba L. Here, we investigate the possible role of PTPases in stomatal movement process. Phenylarsine oxide (PAO), a specific inhibitor of PTPases, could prevent ABA or H2O2-induced stomatal closure of Vicia faba L; furthermore, it could promote opening of the stomata closed by ABA or H2O2. The activity of PTPases can be effectively inhibited by PAO and H2O2. DTT had no effect on the PAO-induced inhibition of PTPases activity, but it could relieve the inhibition of H2O2 on PTPases activity. PAO could also inhibit the ABA-induced H2O2 generation in guard cells of Vicia faba L. These results suggested that PTPases is a critical signaling component in ABA-induced stomatal closure, and serve as targets for H2O2 lying on the signaling pathways downstream of ABA induced H2O2 generation.

  7. Mutations in CDC14A, Encoding a Protein Phosphatase Involved in Hair Cell Ciliogenesis, Cause Autosomal-Recessive Severe to Profound Deafness.

    Delmaghani, Sedigheh; Aghaie, Asadollah; Bouyacoub, Yosra; El Hachmi, Hala; Bonnet, Crystel; Riahi, Zied; Chardenoux, Sebastien; Perfettini, Isabelle; Hardelin, Jean-Pierre; Houmeida, Ahmed; Herbomel, Philippe; Petit, Christine

    2016-06-01

    By genetic linkage analysis in a large consanguineous Iranian family with eleven individuals affected by severe to profound congenital deafness, we were able to define a 2.8 Mb critical interval (at chromosome 1p21.2-1p21.1) for an autosomal-recessive nonsyndromic deafness locus (DFNB). Whole-exome sequencing allowed us to identify a CDC14A biallelic nonsense mutation, c.1126C>T (p.Arg376(∗)), which was present in the eight clinically affected individuals still alive. Subsequent screening of 115 unrelated individuals affected by severe or profound congenital deafness of unknown genetic cause led us to identify another CDC14A biallelic nonsense mutation, c.1015C>T (p.Arg339(∗)), in an individual originating from Mauritania. CDC14A encodes a protein tyrosine phosphatase. Immunofluorescence analysis of the protein distribution in the mouse inner ear showed a strong labeling of the hair cells' kinocilia. By using a morpholino strategy to knockdown cdc14a in zebrafish larvae, we found that the length of the kinocilia was reduced in inner-ear hair cells. Therefore, deafness caused by loss-of-function mutations in CDC14A probably arises from a morphogenetic defect of the auditory sensory cells' hair bundles, whose differentiation critically depends on the proper growth of their kinocilium. PMID:27259055

  8. Anti-idiotypic nanobody-alkaline phosphatase fusion proteins: Development of a one-step competitive enzyme immunoassay for fumonisin B1 detection in cereal.

    Shu, Mei; Xu, Yang; Liu, Xing; Li, Yanping; He, Qinghua; Tu, Zhui; Fu, Jinheng; Gee, Shirley J; Hammock, Bruce D

    2016-06-14

    A rapid and sensitive one-step competitive enzyme immunoassay for the detection of FB1 was developed. The anti-idiotypic nanobody-alkaline phosphatase (Ab2β-Nb-AP) was validated by the AP enzyme activity and the properties of bounding to anti-FB1-mAb (3F11) through colorimetric and chemiluminescence analyses. The 50% inhibitory concentration and the detection limit (LOD) of colorimetric enzyme-linked immunosorbent assay (ELISA) for FB1 were 2.69 and 0.35 ng mL(-1), respectively, with a linear range of 0.93-7.73 ng mL(-1). The LOD of the chemiluminescence ELISA (CLIA) was 0.12 ng mL(-1), and the IC50 was 0.89 ± 0.09 ng mL(-1) with a linear range of 0.29-2.68 ng mL(-1). Compared with LC-MS/MS, the results of this assay indicated the reliability of the Ab2β-Nb-AP fusion protein based one-step competitive immunoassay for monitoring FB1 contamination in cereals. The Ab2β-Nb-AP fusion proteins have the potential to replace chemically-coupled probes in competitive enzyme immunoassay systems. PMID:27181644

  9. Effects of epidermal growth factor receptor and phosphatase and tensin homologue gene expression on the inhibition of U87MG glioblastoma cell proliferation induced by protein kinase inhibitors.

    Xing, Wen-Jing; Zou, Yan; Han, Qing-Lian; Dong, Yu-Cui; Deng, Zhen-Ling; Lv, Xiao-Hong; Jiang, Tao; Ren, Huan

    2013-01-01

    The aim of the present study was to analyse the antiproliferative effects and mechanisms of action of protein kinase inhibitors (PKIs) in human glioblastoma multiforme (GBM) cells with different epidermal growth factor receptor (EGFR) and phosphatase and tensin homologue (PTEN) status. The GBM cell models were established by transfection of plasmids carrying wild-type EGFR, mutated EGFRvIII or PTEN and clonal selection in U87MG cells. Phosphatidylinositol 3-kinase (PI3-K)/AKT pathway-focused gene profiles were examined by real-time polymerase chain reaction-based assays, protein expression was evaluated by western blotting and the antiproliferative effects of PKI treatment were determined by the 3-(4,5-dimethyl-2 thiazoyl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay in GBM cells. The cell model with intact PTEN and low EGFR levels was the most sensitive to treatment with the EGFR inhibitor erlotinib, whereas the model with EGFRvIII was the most resistant to treatment with the mitogen-activated protein kinase kinase inhibitor U0126. The dual PI3-K and mammalian target of rapamycin (mTOR) inhibitor PI103 had the most potent antiproliferative effects against all GBM cells tested. Following simultaneous stimulation of AKT and extracellular signal-regulated kinase, rapamycin concentrations > 0.5 nmol/L failed to exhibit a further growth inhibitory effect. Concurrent inhibition of mTOR and ribosomal protein s6 activity may underlie the inhibition of GBM proliferation by PKI. In conclusion, overexpression of EGFR or EGFRvIII, accompanied by a loss of PTEN, contributed to the activation of multiple intracellular signalling pathways in GBM cells. Rigorous examination of biomarkers in tumour tissues before and after treatment may be necessary to determine the efficacy of PKI therapy in patients with GBM. PMID:23110505

  10. Long-acting β2-agonists increase fluticasone propionate-induced mitogen-activated protein kinase phosphatase 1 (MKP-1 in airway smooth muscle cells.

    Melanie Manetsch

    Full Text Available Mitogen-activated protein kinase phosphatase 1 (MKP-1 represses MAPK-driven signalling and plays an important anti-inflammatory role in asthma and airway remodelling. Although MKP-1 is corticosteroid-responsive and increased by cAMP-mediated signalling, the upregulation of this critical anti-inflammatory protein by long-acting β2-agonists and clinically-used corticosteroids has been incompletely examined to date. To address this, we investigated MKP-1 gene expression and protein upregulation induced by two long-acting β2-agonists (salmeterol and formoterol, alone or in combination with the corticosteroid fluticasone propionate (abbreviated as fluticasone in primary human airway smooth muscle (ASM cells in vitro. β2-agonists increased MKP-1 protein in a rapid but transient manner, while fluticasone induced sustained upregulation. Together, long-acting β2-agonists increased fluticasone-induced MKP-1 and modulated ASM synthetic function (measured by interleukin 6 (IL-6 and interleukin 8 (IL-8 secretion. As IL-6 expression (like MKP-1 is cAMP/adenylate cyclase-mediated, the long-acting β2-agonist formoterol increased IL-6 mRNA expression and secretion. Nevertheless, when added in combination with fluticasone, β2-agonists significantly repressed IL-6 secretion induced by tumour necrosis factor α (TNFα. Conversely, as IL-8 is not cAMP-responsive, β2-agonists significantly inhibited TNFα-induced IL-8 in combination with fluticasone, where fluticasone alone was without repressive effect. In summary, long-acting β2-agonists increase fluticasone-induced MKP-1 in ASM cells and repress synthetic function of this immunomodulatory airway cell type.

  11. Development of a single-chain variable fragment-alkaline phosphatase fusion protein and a sensitive direct competitive chemiluminescent enzyme immunoassay for detection of ractopamine in pork

    Dong Jiexian; Li Zhenfeng; Lei Hongtao; Sun Yuanming [Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642 (China); Ducancel, Frederic [CEA, iBiTec-S, Service de Pharmacologie et d' Immnoanalyse (SPI), CEA Saclay, F-91191 Gif sur Yvette (France); Xu Zhenlin [Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642 (China); Boulain, Jean-Claude [CEA, iBiTec-S, Service de Pharmacologie et d' Immnoanalyse (SPI), CEA Saclay, F-91191 Gif sur Yvette (France); Yang Jinyi; Shen Yudong [Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642 (China); Wang Hong, E-mail: gzwhongd@63.com [Guangdong Provincial Key Laboratory of Food Quality and Safety, South China Agricultural University, Guangzhou 510642 (China)

    2012-07-29

    Graphical abstract: Detection model of dc-CLEIA based on anti-RAC scFv-AP fusion protein. Highlights: Black-Right-Pointing-Pointer The scFv-AP fusion protein against ractopamine (RAC) was produced. Black-Right-Pointing-Pointer A dc-CLEIA for RAC was developed based on the purified scFv-AP fusion protein. Black-Right-Pointing-Pointer The sensitivity of dc-CLEIA was 10 times as sensitive as dc-ELISA for RAC. Black-Right-Pointing-Pointer Recovery tests from pork samples were studied. Black-Right-Pointing-Pointer Good accuracy was obtained. - Abstract: A rapid, sensitive chemiluminescent enzyme immunoassay (CLEIA) for ractopamine (RAC) based on a single-chain variable fragment (scFv)-alkaline phosphatase (AP) fusion protein was developed. The scFv gene was prepared by cloning the heavy- and light-chain variable region genes (V{sub H} and V{sub L}) from hybridoma cell line AC2, which secretes antibodies against RAC, and assembling V{sub H} and V{sub L} genes with a linker by means of splicing overlap extension polymerase chain reaction. The resulting scFv gene was inserted into the expression vector pLIP6/GN containing AP to produce the fusion protein in Escherichia coli strain BL21. The purified scFv-AP fusion protein was used to develop a direct competitive CLEIA (dcCLEIA) protocol for detection of RAC. The average concentration required for 50% inhibition of binding and the limit of detection of the assay were 0.25 {+-} 0.03 and 0.02 {+-} 0.004 ng mL{sup -1}, respectively, and the linear response range extended from 0.05 to 1.45 ng mL{sup -1}. The assay was 10 times as sensitive as the corresponding enzyme-linked immunosorbent assay based on the same fusion protein. Cross-reactivity studies showed that the fusion protein did not cross react with RAC analogs. DcCLEIA was used to analyze RAC spiked pork samples, and the validation was confirmed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS). The results showed a good correlation between

  12. Development of a single-chain variable fragment-alkaline phosphatase fusion protein and a sensitive direct competitive chemiluminescent enzyme immunoassay for detection of ractopamine in pork

    Graphical abstract: Detection model of dc-CLEIA based on anti-RAC scFv-AP fusion protein. Highlights: ► The scFv-AP fusion protein against ractopamine (RAC) was produced. ► A dc-CLEIA for RAC was developed based on the purified scFv-AP fusion protein. ► The sensitivity of dc-CLEIA was 10 times as sensitive as dc-ELISA for RAC. ► Recovery tests from pork samples were studied. ► Good accuracy was obtained. - Abstract: A rapid, sensitive chemiluminescent enzyme immunoassay (CLEIA) for ractopamine (RAC) based on a single-chain variable fragment (scFv)-alkaline phosphatase (AP) fusion protein was developed. The scFv gene was prepared by cloning the heavy- and light-chain variable region genes (VH and VL) from hybridoma cell line AC2, which secretes antibodies against RAC, and assembling VH and VL genes with a linker by means of splicing overlap extension polymerase chain reaction. The resulting scFv gene was inserted into the expression vector pLIP6/GN containing AP to produce the fusion protein in Escherichia coli strain BL21. The purified scFv-AP fusion protein was used to develop a direct competitive CLEIA (dcCLEIA) protocol for detection of RAC. The average concentration required for 50% inhibition of binding and the limit of detection of the assay were 0.25 ± 0.03 and 0.02 ± 0.004 ng mL−1, respectively, and the linear response range extended from 0.05 to 1.45 ng mL−1. The assay was 10 times as sensitive as the corresponding enzyme-linked immunosorbent assay based on the same fusion protein. Cross-reactivity studies showed that the fusion protein did not cross react with RAC analogs. DcCLEIA was used to analyze RAC spiked pork samples, and the validation was confirmed by high-performance liquid chromatography–tandem mass spectrometry (HPLC–MS). The results showed a good correlation between the data of dc-CLEIA and HPLC–MS (R2 > 0.99), indicating that the assay was an efficient analytical method for monitoring food safety.

  13. Structural Studies of Soybean Calmodulin Isoform 4 Bound to the Calmodulin-binding Domain of Tobacco Mitogen-activated Protein Kinase Phosphatase-1 Provide Insights into a Sequential Target Binding Mode*

    Ishida, Hiroaki; Rainaldi, Mario; Vogel, Hans J.

    2009-01-01

    The calcium regulatory protein calmodulin (CaM) binds in a calcium-dependent manner to numerous target proteins. The calmodulin-binding domain (CaMBD) region of Nicotiana tabacum MAPK phosphatase has an amino acid sequence that does not resemble the CaMBD of any other known Ca2+-CaM-binding proteins. Using a unique fusion protein strategy, we have been able to obtain a high resolution solution structure of the complex of soybean Ca2+-CaM4 (SCaM4) and this CaMBD. Complete isotope labeling of b...

  14. Protein kinase C (PKC) phosphorylates human platelet inositol trisphosphate 5/sup +/-/-phosphomonoesterase (IP3 5'-p'tase) increasing phosphatase activity

    Phosphoinositide breakdown in response to thrombin stimulation of human platelets generates messenger molecules that activate PKC (diglyceride) and mobilize Ca++ (inositol tris-phosphates). The water soluble products of phospholipase C-mediated metabolism of phosphatidylinositol 4,5-diphosphate are inositol 1,4,5 P3 (IP3) and inositol 1:2-cyclic 4,5 P3 (cIP3). A specific phosphatase, IP3 5'-p'tase, cleaves the 5 phosphate from IP3 or cIP3 to form IP2 or cIP2 and P/sub i/, none of which mobilizes Ca++. Thus, the IP3 5'-p'tase may regulate cellular responses to IP3 or cIP3. The authors find that IP3 5'-p'tase isolated from human platelets is phosphorylated by rat brain PKC, resulting in a 4-fold increase in IP3 5'-p'tase activity. The authors phosphorylated IP3 5'-p'tase using γ 32P-ATP and found that the labeled enzyme comigrated on SDS-PAGE with the previously described 40K protein phosphorylated in response to thrombin stimulation of platelets. The similarity of the PKC-phosphorylated IP3 5'-p'tase observed in vitro and the thrombin-stimulated phosphorylated 40K protein known to be phosphorylated by PKC in vivo, suggests that these proteins may be the same. These results suggest that platelet Ca++ mobilization maybe regulated by PKC phosphorylation of the IP3 5'-p'tase and can explain the observation that phorbol ester treatment of intact human platelets results in decreased production of IP3 and decreased Ca++ mobilization upon subsequent thrombin addition

  15. Identification of an alkaline phosphatase as a putative Cry1Ac binding protein in Ostrinia furnacalis (Guenée).

    Jin, Tingting; Duan, Xiaoli; Bravo, Alejandra; Soberón, Mario; Wang, Zhenying; He, Kanglai

    2016-07-01

    Asian corn borer (ACB), Ostrinia furnacalis, is an important insect pest of maize susceptible to different Cry1A toxins. Based on amino acid sequence alignment of ALP sequences from lepidopteran larvae an alp gene was cloned from ACB, named ofalp. Pull dawn assays using biotinylated Cry1Ac and brush border membrane vesicles isolated from second instar ACB larvae showed that four proteins of 50, 65, 68 and 70kDa precipitated with the Cry1Ac. The 65kDa band cross-reacted with the anti-OfALP monoclonal antibody. GalNac was able to release the binding of Cry1Ac to the 65kDa OfALP in pull down assays. A 37kDa fragment from residues D173 to D473 of OfALP was cloned and expressed in Escherichia coli cells. We show that this ALP-fragment was able to bind Cry1Ac in ligand blot analysis. Our data also indicate that different ALP isoforms or variants may be also Cry1Ac binding proteins since more ALP enzymatic activity was pull down with Cry1Ac than with anti-OfALP antibody. We also analyzed the expression levels of ALP throughout the larval development by qPCR and ALP enzymatic activity. Our data indicated that ALP expression in ACB was observed preferentially in young instar larvae. Finally, we show that resistance in O. furnacalis ACB-AcR strain resistant to Cry1Ac did not correlate with changes in expression of this ALP protein since it shows similar gene expression of ofalp than the susceptible insect strain. Identification of Cry1Ac receptors will help to understand mechanism of action of Cry1Ac in O. furnacalis and to understand mechanism of Cry toxin resistance. Our data indicate that at least one ALP protein is involved in the binding interaction with Cry1Ac in O. furnacalis. PMID:27265829

  16. Phosphatase-Dependent Regulation of Epithelial Mitogen-Activated Protein Kinase Responses to Toxin-Induced Membrane Pores

    Aguilar, Jorge L.; Kulkarni, Ritwij; Randis, Tara M.; Soman, Sandeep; Kikuchi, Alexander; Yin, Yuxin; Ratner, Adam J.

    2009-01-01

    Diverse bacterial species produce pore-forming toxins (PFT) that can puncture eukaryotic cell membranes. Host cells respond to sublytic concentrations of PFT through conserved intracellular signaling pathways, including activation of mitogen-activated protein kinases (MAPK), which are critical to cell survival. Here we demonstrate that in respiratory epithelial cells p38 and JNK MAPK were phosphorylated within 30 min of exposure to pneumolysin, the PFT from Streptococcus pneumoniae. This acti...

  17. Deletion of protein tyrosine phosphatase, non-receptor type 4 (PTPN4) in twins with a Rett syndrome-like phenotype.

    Williamson, Sarah L; Ellaway, Carolyn J; Peters, Greg B; Pelka, Gregory J; Tam, Patrick P L; Christodoulou, John

    2015-09-01

    Rett syndrome (RTT), a neurodevelopmental disorder that predominantly affects females, is primarily caused by variants in MECP2. Variants in other genes such as CDKL5 and FOXG1 are usually associated with individuals who manifest distinct phenotypes that may overlap with RTT. Individuals with phenotypes suggestive of RTT are typically screened for variants in MECP2 and then subsequently the other genes dependent on the specific phenotype. Even with this screening strategy, there are individuals in whom no causative variant can be identified, suggesting that there are other novel genes that contribute to the RTT phenotype. Here we report a de novo deletion of protein tyrosine phosphatase, non-receptor type 4 (PTPN4) in identical twins with a RTT-like phenotype. We also demonstrate the reduced expression of Ptpn4 in a Mecp2 null mouse model of RTT, as well as the activation of the PTPN4 promoter by MeCP2. Our findings suggest that PTPN4 should be considered for addition to the growing list of genes that warrant screening in individuals with a RTT-like phenotype. PMID:25424712

  18. MicroRNA-194 promotes the growth, migration, and invasion of ovarian carcinoma cells by targeting protein tyrosine phosphatase nonreceptor type 12

    Liang, Tian; Li, Liru; Cheng, Yan; Ren, Chengcheng; Zhang, Guangmei

    2016-01-01

    Ovarian carcinoma is the most lethal gynecologic malignancy among women. Ovarian cancer metastasis is the main reason for poor prognosis. MicroRNAs (miRNAs) have been shown to play an important role in tumorigenesis and metastasis in various cancers by affecting the expression of their targets. In this study, we explored the role of miR-194 in ovarian cancer. Real-time polymerase chain reaction assays showed that miR-194 was significantly upregulated in ovarian cancer tissues. Overexpression of miR-194 in ovarian cancer cells promotes cell proliferation, migration, and invasion; in contrast, inhibition of the expression of miR-194 has the opposite effects. Meanwhile, bioinformatics tools were used to identify protein tyrosine phosphatase nonreceptor type 12 (PTPN12) as a potential target of miR-194. The luciferase assay showed that miR-194 directly binds to the 3′-untranslated region of PTPN12. Western blot analysis and quantitative real-time polymerase chain reaction assay revealed that PTPN12 expression was negatively associated with miR-194 expression in both ovarian cancer tissues and cells. Thus, we conclude that miR-194 targets PTPN12 and functions as an oncogene in ovarian cancer cells. This novel pathway may provide a new insight to explain ovarian cancer development and metastasis. PMID:27486333

  19. Identification of PGAM5 as a Mammalian Protein Histidine Phosphatase that Plays a Central Role to Negatively Regulate CD4(+) T Cells.

    Panda, Saswati; Srivastava, Shekhar; Li, Zhai; Vaeth, Martin; Fuhs, Stephen R; Hunter, Tony; Skolnik, Edward Y

    2016-08-01

    Whereas phosphorylation of serine, threonine, and tyrosine is exceedingly well characterized, the role of histidine phosphorylation in mammalian signaling is largely unexplored. Here we show that phosphoglycerate mutase family 5 (PGAM5) functions as a phosphohistidine phosphatase that specifically associates with and dephosphorylates the catalytic histidine on nucleoside diphosphate kinase B (NDPK-B). By dephosphorylating NDPK-B, PGAM5 negatively regulates CD4(+) T cells by inhibiting NDPK-B-mediated histidine phosphorylation and activation of the K(+) channel KCa3.1, which is required for TCR-stimulated Ca(2+) influx and cytokine production. Using recently developed monoclonal antibodies that specifically recognize phosphorylation of nitrogens at the N1 (1-pHis) or N3 (3-pHis) positions of the imidazole ring, we detect for the first time phosphoisoform-specific regulation of histidine-phosphorylated proteins in vivo, and we link these modifications to TCR signaling. These results represent an important step forward in studying the role of histidine phosphorylation in mammalian biology and disease. PMID:27453048

  20. Protein Phosphatase 2A Catalytic Subunit α Plays a MyD88-Dependent, Central Role in the Gene-Specific Regulation of Endotoxin Tolerance

    Ling Xie

    2013-03-01

    Full Text Available MyD88, the intracellular adaptor of most TLRs, mediates either proinflammatory or immunosuppressive signaling that contributes to chronic inflammation-associated diseases. Although gene-specific chromatin modifications regulate inflammation, the role of MyD88 signaling in establishing such epigenetic landscapes under different inflammatory states remains elusive. Using quantitative proteomics to enumerate the inflammation-phenotypic constituents of the MyD88 interactome, we found that in endotoxin-tolerant macrophages, protein phosphatase 2A catalytic subunit α (PP2Ac enhances its association with MyD88 and is constitutively activated. Knockdown of PP2Ac prevents suppression of proinflammatory genes and resistance to apoptosis. Through site-specific dephosphorylation, constitutively active PP2Ac disrupts the signal-promoting TLR4-MyD88 complex and broadly suppresses the activities of multiple proinflammatory/proapoptotic pathways as well, shifting proinflammatory MyD88 signaling to a prosurvival mode. Constitutively active PP2Ac translocated with MyD88 into the nuclei of tolerant macrophages establishes the immunosuppressive pattern of chromatin modifications and represses chromatin remodeling to selectively silence proinflammatory genes, coordinating the MyD88-dependent inflammation control at both signaling and epigenetic levels under endotoxin-tolerant conditions.

  1. The microRNA cluster miR-183/96/182 contributes to long-term memory in a protein phosphatase 1-dependent manner

    Woldemichael, Bisrat T.; Jawaid, Ali; Kremer, Eloïse A.; Gaur, Niharika; Krol, Jacek; Marchais, Antonin; Mansuy, Isabelle M.

    2016-01-01

    Memory formation is a complex cognitive function regulated by coordinated synaptic and nuclear processes in neurons. In mammals, it is controlled by multiple molecular activators and suppressors, including the key signalling regulator, protein phosphatase 1 (PP1). Here, we show that memory control by PP1 involves the miR-183/96/182 cluster and its selective regulation during memory formation. Inhibiting nuclear PP1 in the mouse brain, or training on an object recognition task similarly increases miR-183/96/182 expression in the hippocampus. Mimicking this increase by miR-183/96/182 overexpression enhances object memory, while knocking-down endogenous miR-183/96/182 impairs it. This effect involves the modulation of several plasticity-related genes, with HDAC9 identified as an important functional target. Further, PP1 controls miR-183/96/182 in a transcription-independent manner through the processing of their precursors. These findings provide novel evidence for a role of miRNAs in memory formation and suggest the implication of PP1 in miRNAs processing in the adult brain. PMID:27558292

  2. Structure of the Trypanosoma cruzi protein tyrosine phosphatase TcPTP1, a potential therapeutic target for Chagas' disease

    Lountos, George T.; Tropea, Joseph E.; Waugh, David S. [FNL

    2013-06-05

    Chagas’ disease, a neglected tropical affliction transmitted by the flagellated protozoan Trypanosoma cruzi, is prevalent in Latin America and affects nearly 18 million people worldwide, yet few approved drugs are available to treat the disease. Moreover, the currently available drugs exhibit severe toxicity or are poorly effective in the chronic phase of the disease. This limitation, along with the large population at risk, underscores the urgent need to discover new molecular targets and novel therapeutic agents. Recently, the T. cruzi protein tyrosine phosphatase TcPTP1 has been implicated in the cellular differentiation and infectivity of the parasite and is therefore a promising target for the design of novel anti-parasitic drugs. Here, we report the X-ray crystal structure of TcPTP1 refined to a resolution of 2.18 Å, which provides structural insights into the active site environment that can be used to initiate structure-based drug design efforts to develop specific TcPTP1 inhibitors. Potential strategies to develop such inhibitors are also discussed.

  3. Inflammation-induced radioresistance is mediated by ROS-dependent inactivation of protein phosphatase 1 in non-small cell lung cancer cells.

    Kim, Wanyeon; Youn, HyeSook; Kang, ChulHee; Youn, BuHyun

    2015-09-01

    Inflammation plays a pivotal role in modulating the radiation responsiveness of tumors. We determined that an inflammation response prior to irradiation contributes to radiotherapy resistance in non-small cell lung cancer (NSCLC) cells. In the clonogenic survival assay, activation of the inflammation response by lipopolysaccharide (LPS) decreased the degree of radiosensitivity in NCI-H460 cells (relatively radiosensitive cells), but had no effect in A549 cells (relatively radioresistant cells). LPS-induced radioresistance of NCI-H460 cells was also confirmed with a xenograft mouse model. The radioresistant effect observed in NCI-H460 cells was correlated with inhibition of apoptotic cell death due to reduced Caspase 3/7 activity. Moreover, we found that the levels of reactive oxygen species (ROS) were synergistically elevated in NCI-H460 cells by treatment with LPS and radiation. Increased ROS generation negatively affected the activity of protein phosphatase 1 (PP1). Decreased PP1 activity did not lead to Bad dephosphorylation, consequently resulting in the inhibition of irradiation-induced mitochondrial membrane potential loss and apoptosis. We confirmed that pre-treatment with a PP1 activator and LPS sensitized NCI-H460 cells to radiation. Taken together, our findings provided evidence that PP1 activity is critical for radiosensitization in NSCLC cells and PP1 activators can serve as promising radiosensitizers to improve therapeutic efficacy. PMID:26033480

  4. Sulfone-stabilized carbanions for the reversible covalent capture of a posttranslationally-generated cysteine oxoform found in protein tyrosine phosphatase 1B (PTP1B).

    Parsons, Zachary D; Ruddraraju, Kasi Viswanatharaju; Santo, Nicholas; Gates, Kent S

    2016-06-15

    Redox regulation of protein tyrosine phosphatase 1B (PTP1B) involves oxidative conversion of the active site cysteine thiolate into an electrophilic sulfenyl amide residue. Reduction of the sulfenyl amide by biological thiols regenerates the native cysteine residue. Here we explored fundamental chemical reactions that may enable covalent capture of the sulfenyl amide residue in oxidized PTP1B. Various sulfone-containing carbon acids were found to react readily with a model peptide sulfenyl amide via attack of the sulfonyl carbanion on the electrophilic sulfur center in the sulfenyl amide. Both the products and the rates of these reactions were characterized. The results suggest that capture of a peptide sulfenyl amide residue by sulfone-stabilized carbanions can slow, but not completely prevent, thiol-mediated generation of the corresponding cysteine-containing peptide. Sulfone-containing carbon acids may be useful components in the construction of agents that knock down PTP1B activity in cells via transient covalent capture of the sulfenyl amide oxoform generated during insulin signaling processes. PMID:27132865

  5. The effect of high glucose levels on the hypermethylation of protein phosphatase 1 regulatory subunit 3C (PPP1R3C) gene in colorectal cancer

    Soo Kyung Lee; Ji Wook Moon; Yong Woo Lee; Jung Ok Lee; Su Jin Kim; Nami Kim; Jin Kim; Hyeon Soo Kim; Sun-Hwa Park

    2015-03-01

    DNA methylation is an epigenetic event that occurs frequently in colorectal cancer (CRC). Increased glucose level is a strong risk factor for CRC. Protein phosphatase 1 regulatory subunit 3C (PPP1R3C) modulates glycogen metabolism, particularly glycogen synthesis. The aim of this study was to investigate the effect of high glucose levels on DNA methylation of PPP1R3C in CRC. PPP1R3C was significantly hypermethylated in CRC tissues (76/105, 72.38%, < 0.05) and colon cancer cell lines ( < 0.05). CRC tissues obtained from patients with high glucose levels showed that the methylation of PPP1R3C was lower than in patients who had normal levels of glucose. When DLD-1 cells were cultured under conditions of high glucose, the methylation of PPP1R3C was repressed. The expression of PPP1R3C was inversely related to methylation status. In addition, a promoter luciferase assay showed that the transcriptional activity of PPP1R3C was increased in high glucose culture conditions. The number of cells decreased when PPP1R3C was silenced in DLD-1 cells. These results suggest that PPP1R3C, a novel hypermethylated gene in CRC, may play a critical role in cancer cell growth in association with glucose levels.

  6. Potential Utility of Sodium Selenate as an Adjunct to Metformin in Treating Type II Diabetes Mellitus in Rats: A Perspective on Protein Tyrosine Phosphatase

    Rania M. Salama

    2013-01-01

    Full Text Available Metformin is widely regarded as the standard first-line antidiabetic agent, in terms of efficacy and safety profiles. However, in most patients with type II diabetes mellitus (T2DM, it was found that metformin alone is not enough to adequately control hyperglycemia. Thus, we designed this study with the aim to investigate the effect of sodium selenate, a protein tyrosine phosphatase (PTP inhibitor, individually and as an adjunct to metformin, on a rat model that simulates the metabolic characteristics of human T2DM. T2DM model was achieved by feeding the rats with high-fat, high-fructose diet (HFFD for 8 weeks followed by a low dose of streptozotocin (STZ (35 mg/kg/day, i.p.. Changes in serum glucose, insulin, adiponectin, homeostasis model assessment of insulin resistance (HOMA-IR index, and the lipid profile were assessed. In addition, the level of reduced glutathione (GSH and the activity of PTP were determined in the liver. Results showed that the addition of sodium selenate to metformin was able to restore hepatic GSH back to normal levels. Also, this combination therapy corrected the altered serum total cholesterol (TC, triglycerides (TG, and adiponectin levels. In conclusion, additive therapeutic effect was recorded when sodium selenate was used as an adjunct to metformin.

  7. A role for protein phosphatases 1, 2A, and 2B in cerebellar long-term potentiation

    Belmeguenai, A.; Hansel, Christian

    2005-01-01

    textabstractCerebellar parallel fiber (PF)-Purkinje cell (PC) synapses can undergo postsynaptically expressed long-term depression (LTD) or long-term potentiation (LTP). PF-LTD induction requires the coactivity of the PF and CF (climbing fiber) inputs to PCs and a concomitant calcium transient and activation of protein kinase C (PKC). PF-LTP can be induced by PF activity alone and requires a lower calcium transient for its induction than PF-LTD. The cellular events triggering PF-LTP induction...

  8. The extended human PTPome: a growing tyrosine phosphatase family.

    Alonso, Andrés; Pulido, Rafael

    2016-04-01

    Tyr phosphatases are, by definition, enzymes that dephosphorylate phospho-Tyr (pTyr) from proteins. This activity is found in several structurally diverse protein families, including the protein Tyr phosphatase (PTP), arsenate reductase, rhodanese, haloacid dehalogenase (HAD) and His phosphatase (HP) families. Most of these families include members with substrate specificity for non-pTyr substrates, such as phospho-Ser/phospho-Thr, phosphoinositides, phosphorylated carbohydrates, mRNAs, or inorganic moieties. A Cys is essential for catalysis in PTPs, rhodanese and arsenate reductase enzymes, whereas this work is performed by an Asp in HAD phosphatases and by a His in HPs, via a catalytic mechanism shared by all of the different families. The category that contains most Tyr phosphatases is the PTP family, which, although it received its name from this activity, includes Ser, Thr, inositide, carbohydrate and RNA phosphatases, as well as some inactive pseudophosphatase proteins. Here, we propose an extended collection of human Tyr phosphatases, which we call the extended human PTPome. The addition of new members (SACs, paladin, INPP4s, TMEM55s, SSU72, and acid phosphatases) to the currently categorized PTP group of enzymes means that the extended human PTPome contains up to 125 proteins, of which ~ 40 are selective for pTyr. We set criteria to ascribe proteins to the extended PTPome, and summarize the more important features of the new PTPome members in the context of their phosphatase activity and their relationship with human disease. PMID:26573778

  9. The tyrosine phosphatase SHP-1 regulates hypoxia inducible factor-1α (HIF-1α protein levels in endothelial cells under hypoxia.

    Stefan K Alig

    Full Text Available The tyrosine phosphatase SHP-1 negatively influences endothelial function, such as VEGF signaling and reactive oxygen species (ROS formation, and has been shown to influence angiogenesis during tissue ischemia. In ischemic tissues, hypoxia induced angiogenesis is crucial for restoring oxygen supply. However, the exact mechanism how SHP-1 affects endothelial function during ischemia or hypoxia remains unclear. We performed in vitro endothelial cell culture experiments to characterize the role of SHP-1 during hypoxia.SHP-1 knock-down by specific antisense oligodesoxynucleotides (AS-Odn increased cell growth as well as VEGF synthesis and secretion during 24 hours of hypoxia compared to control AS-Odn. This was prevented by HIF-1α inhibition (echinomycin and apigenin. SHP-1 knock-down as well as overexpression of a catalytically inactive SHP-1 (SHP-1 CS further enhanced HIF-1α protein levels, whereas overexpression of a constitutively active SHP-1 (SHP-1 E74A resulted in decreased HIF-1α levels during hypoxia, compared to wildtype SHP-1. Proteasome inhibition (MG132 returned HIF-1α levels to control or wildtype levels respectively in these cells. SHP-1 silencing did not alter HIF-1α mRNA levels. Finally, under hypoxic conditions SHP-1 knock-down enhanced intracellular endothelial reactive oxygen species (ROS formation, as measured by oxidation of H2-DCF and DHE fluorescence.SHP-1 decreases half-life of HIF-1α under hypoxic conditions resulting in decreased cell growth due to diminished VEGF synthesis and secretion. The regulatory effect of SHP-1 on HIF-1α stability may be mediated by inhibition of endothelial ROS formation stabilizing HIF-1α protein. These findings highlight the importance of SHP-1 in hypoxic signaling and its potential as therapeutic target in ischemic diseases.

  10. Molecular dynamics simulations of protein-tyrosine phosphatase 1B: II. Substrate-enzyme interactions and dynamics

    Peters, Günther H.j.; Frimurer, T. M.; Andersen, J. N.;

    2000-01-01

    protein surface is characterized by a predominantly negative electrostatic field. This positive electrostatic field attracts negatively charged substrates and could explain the experimentally observed preference of PTP1B for negatively charged substrates like the DADEpYL peptide....... substrate flexibility for binding, 3) the electrostatic properties of the enzyme, and 4) the contribution from solvation. The simulations were performed for 1 ns, using explicit water molecules. The last 700 ps of the trajectories was used for analysis determining enthalpic and entropic contributions to...... for catalysis. Analysis of the individual enzyme-substrate interaction energies revealed that mainly electrostatic forces contribute to binding. Indeed, calculation of the electrostatic field of the enzyme reveals that only the field surrounding the binding pocket is positive, while the remaining...

  11. ER-bound protein tyrosine phosphatase PTP1B interacts with Src at the plasma membrane/substrate interface.

    Melisa C Monteleone

    Full Text Available PTP1B is an endoplasmic reticulum (ER anchored enzyme whose access to substrates is partly dependent on the ER distribution and dynamics. One of these substrates, the protein tyrosine kinase Src, has been found in the cytosol, endosomes, and plasma membrane. Here we analyzed where PTP1B and Src physically interact in intact cells, by bimolecular fluorescence complementation (BiFC in combination with temporal and high resolution microscopy. We also determined the structural basis of this interaction. We found that BiFC signal is displayed as puncta scattered throughout the ER network, a feature that was enhanced when the substrate trapping mutant PTP1B-D181A was used. Time-lapse and co-localization analyses revealed that BiFC puncta did not correspond to vesicular carriers; instead they localized at the tip of dynamic ER tubules. BiFC puncta were retained in ventral membrane preparations after cell unroofing and were also detected within the evanescent field of total internal reflection fluorescent microscopy (TIRFM associated to the ventral membranes of whole cells. Furthermore, BiFC puncta often colocalized with dark spots seen by surface reflection interference contrast (SRIC. Removal of Src myristoylation and polybasic motifs abolished BiFC. In addition, PTP1B active site and negative regulatory tyrosine 529 on Src were primary determinants of BiFC occurrence, although the SH3 binding motif on PTP1B also played a role. Our results suggest that ER-bound PTP1B dynamically interacts with the negative regulatory site at the C-terminus of Src at random puncta in the plasma membrane/substrate interface, likely leading to Src activation and recruitment to adhesion complexes. We postulate that this functional ER/plasma membrane crosstalk could apply to a wide array of protein partners, opening an exciting field of research.

  12. Phosphorylation and activation of nuclear Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) by Ca{sup 2+}/calmodulin-dependent protein kinase I (CaMKI)

    Onouchi, Takashi [Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795 (Japan); Sueyoshi, Noriyuki, E-mail: sueyoshi@ag.kagawa-u.ac.jp [Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795 (Japan); Ishida, Atsuhiko [Laboratory of Molecular Brain Science, Graduate School of Integrated Arts and Sciences, Hiroshima University, Higashi-Hiroshima 739-8521 (Japan); Kameshita, Isamu [Department of Life Sciences, Faculty of Agriculture, Kagawa University, Miki-cho, Kagawa 761-0795 (Japan)

    2012-06-15

    Highlights: Black-Right-Pointing-Pointer CaMKP-N/PPM1E underwent proteolytic processing and translocated to cytosol. Black-Right-Pointing-Pointer The proteolysis was effectively inhibited by the proteasome inhibitors. Black-Right-Pointing-Pointer Ser-480 of zebrafish CaMKP-N was phosphorylated by cytosolic CaMKI. Black-Right-Pointing-Pointer Phosphorylation-mimic mutants of CaMKP-N showed enhanced activity. Black-Right-Pointing-Pointer These results suggest that CaMKP-N is regulated by CaMKI. -- Abstract: Nuclear Ca{sup 2+}/calmodulin-dependent protein kinase phosphatase (CaMKP-N/PPM1E) is an enzyme that dephosphorylates and downregulates multifunctional Ca{sup 2+}/calmodulin-dependent protein kinases (CaMKs) as well as AMP-dependent protein kinase. In our previous study, we found that zebrafish CaMKP-N (zCaMKP-N) underwent proteolytic processing and translocated to cytosol in a proteasome inhibitor-sensitive manner. In the present study, we found that zCaMKP-N is regulated by phosphorylation at Ser-480. When zCaMKP-N was incubated with the activated CaMKI, time-dependent phosphorylation of the enzyme was observed. This phosphorylation was significantly reduced when Ser-480 was replaced by Ala, suggesting that CaMKI phosphorylates Ser-480 of zCaMKP-N. Phosphorylation-mimic mutants, S480D and S480E, showed higher phosphatase activities than those of wild type and S480A mutant in solution-based phosphatase assay using various substrates. Furthermore, autophosphorylation of CaMKII after ionomycin treatment was more severely attenuated in Neuro2a cells when CaMKII was cotransfected with the phosphorylation-mimic mutant of zCaMKP-N than with the wild-type or non-phosphorylatable zCaMKP-N. These results strongly suggest that phosphorylation of zCaMKP-N at Ser-480 by CaMKI activates CaMKP-N catalytic activity and thereby downregulates multifunctional CaMKs in the cytosol.

  13. Cyclic AMP-Rap1A signaling mediates cell surface translocation of microvascular smooth muscle α2C-adrenoceptors through the actin-binding protein filamin-2

    Motawea, Hanaa K. B.; Selvi C. Jeyaraj; Eid, Ali H; Mitra, Srabani; Unger, Nicholas T.; Ahmed, Amany A. E.; Flavahan, Nicholas A.; Chotani, Maqsood A.

    2013-01-01

    The second messenger cyclic AMP (cAMP) plays a vital role in vascular physiology, including vasodilation of large blood vessels. We recently demonstrated cAMP activation of Epac-Rap1A and RhoA-Rho-associated kinase (ROCK)-F-actin signaling in arteriolar-derived smooth muscle cells increases expression and cell surface translocation of functional α2C-adrenoceptors (α2C-ARs) that mediate vasoconstriction in small blood vessels (arterioles). The Ras-related small GTPAse Rap1A increased expressio...

  14. Lipid rafts regulate PCB153-induced disruption of occludin and brain endothelial barrier function through protein phosphatase 2A and matrix metalloproteinase-2

    Eum, Sung Yong, E-mail: seum@miami.edu; Jaraki, Dima; András, Ibolya E.; Toborek, Michal

    2015-09-15

    Occludin is an essential integral transmembrane protein regulating tight junction (TJ) integrity in brain endothelial cells. Phosphorylation of occludin is associated with its localization to TJ sites and incorporation into intact TJ assembly. The present study is focused on the role of lipid rafts in polychlorinated biphenyl (PCB)-induced disruption of occludin and endothelial barrier function. Exposure of human brain endothelial cells to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) induced dephosphorylation of threonine residues of occludin and displacement of occludin from detergent-resistant membrane (DRM)/lipid raft fractions within 1 h. Moreover, lipid rafts modulated the reduction of occludin level through activation of matrix metalloproteinase 2 (MMP-2) after 24 h PCB153 treatment. Inhibition of protein phosphatase 2A (PP2A) activity by okadaic acid or fostriecin markedly protected against PCB153-induced displacement of occludin and increased permeability of endothelial cells. The implication of lipid rafts and PP2A signaling in these processes was further defined by co-immunoprecipitation of occludin with PP2A and caveolin-1, a marker protein of lipid rafts. Indeed, a significant MMP-2 activity was observed in lipid rafts and was increased by exposure to PCB153. The pretreatment of MMP-2 inhibitors protected against PCB153-induced loss of occludin and disruption of lipid raft structure prevented the increase of endothelial permeability. Overall, these results indicate that lipid raft-associated processes, such as PP2A and MMP-2 activation, participate in PCB153-induced disruption of occludin function in brain endothelial barrier. This study contributes to a better understanding of the mechanisms leading to brain endothelial barrier dysfunction in response to exposure to environmental pollutants, such as ortho-substituted PCBs. - Highlights: • PCB153 disturbed human brain endothelial barrier through disruption of occludin. • Lipid raft-associated PP

  15. Lipid rafts regulate PCB153-induced disruption of occludin and brain endothelial barrier function through protein phosphatase 2A and matrix metalloproteinase-2

    Occludin is an essential integral transmembrane protein regulating tight junction (TJ) integrity in brain endothelial cells. Phosphorylation of occludin is associated with its localization to TJ sites and incorporation into intact TJ assembly. The present study is focused on the role of lipid rafts in polychlorinated biphenyl (PCB)-induced disruption of occludin and endothelial barrier function. Exposure of human brain endothelial cells to 2,2′,4,4′,5,5′-hexachlorobiphenyl (PCB153) induced dephosphorylation of threonine residues of occludin and displacement of occludin from detergent-resistant membrane (DRM)/lipid raft fractions within 1 h. Moreover, lipid rafts modulated the reduction of occludin level through activation of matrix metalloproteinase 2 (MMP-2) after 24 h PCB153 treatment. Inhibition of protein phosphatase 2A (PP2A) activity by okadaic acid or fostriecin markedly protected against PCB153-induced displacement of occludin and increased permeability of endothelial cells. The implication of lipid rafts and PP2A signaling in these processes was further defined by co-immunoprecipitation of occludin with PP2A and caveolin-1, a marker protein of lipid rafts. Indeed, a significant MMP-2 activity was observed in lipid rafts and was increased by exposure to PCB153. The pretreatment of MMP-2 inhibitors protected against PCB153-induced loss of occludin and disruption of lipid raft structure prevented the increase of endothelial permeability. Overall, these results indicate that lipid raft-associated processes, such as PP2A and MMP-2 activation, participate in PCB153-induced disruption of occludin function in brain endothelial barrier. This study contributes to a better understanding of the mechanisms leading to brain endothelial barrier dysfunction in response to exposure to environmental pollutants, such as ortho-substituted PCBs. - Highlights: • PCB153 disturbed human brain endothelial barrier through disruption of occludin. • Lipid raft-associated PP

  16. Cellular distribution of the embryonic isoform of microtubule-associated protein 2 (MAP2c) in mid- to late gestation fetal telencephalon

    Cruz, M.; Legido, A.; Del Valle, L.; Pina-Oviedo, S.; Valencia, I.; Dráberová, Eduarda; Dráber, Pavel; Katsetos, C.D.

    2008-01-01

    Roč. 64, č. 12 (2008), S94-S94. ISSN 0364-5134 R&D Projects: GA MŠk LC545; GA ČR GA204/05/2375 Institutional research plan: CEZ:AV0Z50520514 Keywords : MAP2c * telencephalon Subject RIV: EB - Genetics ; Molecular Biology

  17. A simple and visible colorimetric method through Zr(4+)-phosphate coordination for the assay of protein tyrosine phosphatase 1B and screening of its inhibitors.

    Zhang, Juan; Lv, Jun; Wang, Xiaonan; Li, Defeng; Wang, Zhaoxia; Li, Genxi

    2015-08-21

    Inhibitors of protein tyrosine phosphatase 1B (PTP1B) are promising agents for the treatment of type 2 diabetes and obesity, so a colorimetric method has been developed in this work for PTP1B assay and screening of its inhibitors. The method is based on the chelation effect of zirconium (Zr(4+)) ions on the phosphate group, which may induce aggregation of 4-aminophenylphosphate-functionalized gold nanoparticles (APP/AuNPs) and the corresponding color change of the testing solution. Owing to the dephosphorylation of PTP1B, the aggregation of AuNPs will be influenced by PTP1B since there is no coordination reactivity between Zr(4+) ions and 4-aminophenol, the hydrolyzed product of APP catalyzed by the enzyme. Therefore, a simple colorimetric method for the assay of PTP1B activity can be developed. Under the optimized experimental conditions, the ratios of absorbance at a wavelength of 650 nm to that at 522 nm vary linearly with the PTP1B activity in the range from 0.005 to 0.18 U mL(-1) with the lowest detection limit of 0.0017 U mL(-1). Moreover, using this proposed method, the inhibition effect of 6-chloro-3-formyl-7-methylchromone, betulinic acid, ursolic acid, and sodium orthovanadate on PTP1B activity can be tested with IC50 values of 10, 13, 9, and 1.1 μM, respectively. Therefore, this new method has great potential not only for the detection of PTP1B activity but also for the screening of the inhibitors. PMID:26153652

  18. Adipocyte-specific protein tyrosine phosphatase 1B deletion increases lipogenesis, adipocyte cell size and is a minor regulator of glucose homeostasis.

    Carl Owen

    Full Text Available Protein tyrosine phosphatase 1B (PTP1B, a key negative regulator of leptin and insulin signaling, is positively correlated with adiposity and contributes to insulin resistance. Global PTP1B deletion improves diet-induced obesity and glucose homeostasis via enhanced leptin signaling in the brain and increased insulin signaling in liver and muscle. However, the role of PTP1B in adipocytes is unclear, with studies demonstrating beneficial, detrimental or no effect(s of adipose-PTP1B-deficiency on body mass and insulin resistance. To definitively establish the role of adipocyte-PTP1B in body mass regulation and glucose homeostasis, adipocyte-specific-PTP1B knockout mice (adip-crePTP1B(-/- were generated using the adiponectin-promoter to drive Cre-recombinase expression. Chow-fed adip-crePTP1B(-/- mice display enlarged adipocytes, despite having similar body weight/adiposity and glucose homeostasis compared to controls. High-fat diet (HFD-fed adip-crePTP1B(-/- mice display no differences in body weight/adiposity but exhibit larger adipocytes, increased circulating glucose and leptin levels, reduced leptin sensitivity and increased basal lipogenesis compared to controls. This is associated with decreased insulin receptor (IR and Akt/PKB phosphorylation, increased lipogenic gene expression and increased hypoxia-induced factor-1-alpha (Hif-1α expression. Adipocyte-specific PTP1B deletion does not beneficially manipulate signaling pathways regulating glucose homeostasis, lipid metabolism or adipokine secretion in adipocytes. Moreover, PTP1B does not appear to be the major negative regulator of the IR in adipocytes.

  19. Phase I Dose Escalation Study of Sodium Stibogluconate (SSG, a Protein Tyrosine Phosphatase Inhibitor, Combined with Interferon Alpha for Patients with Solid Tumors

    Aung Naing, James M. Reuben, Luis H. Camacho, Hui Gao, Bang-Ning Lee, Evan N. Cohen, Claire Verschraegen, Saneese Stephen, Joann Aaron, David Hong, Jennifer Wheler, Razelle Kurzrock

    2011-01-01

    Full Text Available Purpose: Sodium stibogluconate (SSG, a small molecule inhibitor of protein tyrosine phosphatases, combined with IFN-alpha-2b (IFN-α inhibited solid tumor cell line growth in vitro. We conducted a phase I clinical trial with SSG plus IFN-α in advanced cancer patients to assess tolerance, maximum tolerated dose (MTD and immune system effects.Experimental Design: SSG was administered intravenously alone for five days of week 1, cycle 1 (21 days per cycle and together with IFN-α 2b s (3 million units sc TIW in week 2, and after a rest during week 3, on a 2-week on/1-week off cycle. SSG dose levels were 400, 600, 900, 1125, and 1350 mg/m2.Results: Twenty-four patients were studied. Common toxicities included asymptomatic elevated serum lipase, thrombocytopenia, fatigue, fever, chills and anemia. The dose-limiting toxicities (DLT were hypokalemia, thrombocytopenia, fatigue, pancreatitis and skin rash. The MTD was 900 mg/m2 SSG and IFN-α, 3 million units TIW. At this dose, patients had a significantly lower number of regulatory T cells (TR Cells (p = 0.012, myeloid dendritic cells (mDC (p = 0.028; higher percentage of natural killer (NK cells that synthesized perforin (p = 0.046 and of plasmacytoid dendritic cells (pDC that secreted IFN-α (p = 0.018 in response to activation through toll-like receptor (TLR 7 and TLR 8 by CL097, the highly water-soluble derivative of the imidazoquinoline compound R848.Conclusions: SSG in combination with IFN-α 2b was well tolerated and augmented cellular immune parameters.

  20. Inhibition of protein tyrosine phosphatase activity mediates epidermal growth factor receptor signaling in human airway epithelial cells exposed to Zn2+

    Epidemiological studies have implicated zinc (Zn2+) in the toxicity of ambient particulate matter (PM) inhalation. We previously showed that exposure to metal-laden PM inhibits protein tyrosine phosphatase (PTP) activity in human primary bronchial epithelial cells (HAEC) and leads to Src-dependent activation of EGFR signaling in B82 and A431 cells. In order to elucidate the mechanism of Zn2+-induced EGFR activation in HAEC, we treated HAEC with 500 μM ZnSO4 for 5-20 min and measured the state of activation of EGFR, c-Src and PTPs. Western blots revealed that exposure to Zn2+ results in increased phosphorylation at both trans- and autophosphorylation sites in the EGFR. Zn2+-mediated EGFR phosphorylation did not require ligand binding and was ablated by the EGFR kinase inhibitor PD153035, but not by the Src kinase inhibitor PP2. Src activity was inhibited by Zn2+ treatment of HAEC, consistent with Src-independent EGFR transactivation in HAEC exposed to Zn2+. The rate of exogenous EGFR dephosphorylation in lysates of HAEC exposed to Zn2+ or V4+ was significantly diminished. Moreover, exposure of HAEC to Zn2+ also resulted in a significant impairment of dephosphorylation of endogenous EGFR. These data show that Zn2+-induced activation of EGFR in HAEC involves a loss of PTP activities whose function is to dephosphorylate EGFR in opposition to baseline EGFR kinase activity. These findings also suggest that there are marked cell-type-specific differences in the mechanism of EGFR activation induced by Zn2+ exposure

  1. Characterisation and expression of a PP1 serine/threonine protein phosphatase (PfPP1 from the malaria parasite, Plasmodium falciparum: demonstration of its essential role using RNA interference

    Musiyenko Alla

    2002-04-01

    Full Text Available Abstract Background Reversible protein phosphorylation is relatively unexplored in the intracellular protozoa of the Apicomplexa family that includes the genus Plasmodium, to which belong the causative agents of malaria. Members of the PP1 family represent the most highly conserved protein phosphatase sequences in phylogeny and play essential regulatory roles in various cellular pathways. Previous evidence suggested a PP1-like activity in Plasmodium falciparum, not yet identified at the molecular level. Results We have identified a PP1 catalytic subunit from P. falciparum and named it PfPP1. The predicted primary structure of the 304-amino acid long protein was highly similar to PP1 sequences of other species, and showed conservation of all the signature motifs. The purified recombinant protein exhibited potent phosphatase activity in vitro. Its sensitivity to specific phosphatase inhibitors was characteristic of the PP1 class. The authenticity of the PfPP1 cDNA was further confirmed by mutational analysis of strategic amino acid residues important in catalysis. The protein was expressed in all erythrocytic stages of the parasite. Abrogation of PP1 expression by synthetic short interfering RNA (siRNA led to inhibition of parasite DNA synthesis. Conclusions The high sequence similarity of PfPP1 with other PP1 members suggests conservation of function. Phenotypic gene knockdown studies using siRNA confirmed its essential role in the parasite. Detailed studies of PfPP1 and its regulation may unravel the role of reversible protein phosphorylation in the signalling pathways of the parasite, including glucose metabolism and parasitic cell division. The use of siRNA could be an important tool in the functional analysis of Apicomplexan genes.

  2. [Phosphatase activity in Amoeba proteus at pH 9.0].

    Sopina, V A

    2007-01-01

    In the free-living amoeba Amoeba proteus (strain B), after PAAG disk-electrophoresis of the homogenate supernatant, at using 1-naphthyl phosphate as a substrate and pH 9.0, three forms of phosphatase activity were revealed; they were arbitrarily called "fast", "intermediate", and "slow" phosphatases. The fast phosphatase has been established to be a fraction of lysosomal acid phosphatase that preserves some low activity at alkaline pH. The question as to which particular class the intermediate phosphatase belongs to has remained unanswered: it can be both acid phosphatase and protein tyrosine phosphatase (PTP). Based on data of inhibitor analysis, large substrate specificity, results of experiments with reactivation by Zn ions after inactivation with EDTA, other than in the fast and intermediate phosphatases localization in the amoeba cell, it is concluded that only slow phosphatase can be classified as alkaline phosphatase (EC 3.1.3.1). PMID:17933343

  3. Protein phosphatase 2A plays a critical role in interleukin-2-induced beta 2-integrin dependent homotypic adhesion in human CD4+ T cell lines

    Brockdorff, J; Nielsen, M; Svejgaard, A;

    1997-01-01

    Besides its function as a growth factor for T lymphocytes, interleukin 2 (IL-2) induces beta 2-integrin mediated adhesion, migration, and extravasation of T lymphocytes. It is, however, largely unknown how IL-2 receptors (IL-2R) are coupled to the beta 2-integrin adhesion pathway. Because IL-2...... modulates enzymatic activity and/or subcellular distribution of serine/threonine phosphatases 1 and 2A (PP1/PP2A) in T cells, we examined the role of these phosphatases in IL-2 induced homotypic adhesion in antigen specific human CD4+ T cell lines. We show that calyculin A, a potent inhibitor of PP1 and PP2...... inhibitory effect on cytokine induced adhesion at concentrations which strongly inhibited phosphatase activity. In conclusion, these data provide evidence that PP2A plays a critical role in IL-2-induced beta 2-integrin-dependent adhesion of human T cell lines....

  4. 蛋白酪氨酸磷酸酶相互作用蛋白51的研究进展%Research progress on protein tyrosine phosphatase interacting protein 51

    肖玉霞

    2012-01-01

    蛋白酪氨酸磷酸酶相互作用蛋白(PTPIP)51是一种进化保守的蛋白质,在人类和多种哺乳动物中具有同源性.PTPIP51蛋白表达十分广泛,在不同的组织可有不同的相对分子质量:在不同组织中可与相应的细胞因子结合,具有不同的功能;与多种受体复合物结合.触发和启动多种信号通路的级联反应,参与细胞的代谢、增殖和分化以及功能活动、程序性死亡和迁移等过程.本文就PTPIP51的生物学特性、表达及其调节、信号配体和生理功能以及与肿瘤的关系等研究进展作一综述.%The protein tyrosine phosphatase interacting protein 51 (PTPIP51) was a conserved protein whose amino acid sequence of human was found sequence homology with several other mammalian species. The expression profile of PTPIP51 protein were widely found in human and there were several different calculated molecular masses of the protein in a tissue-specific manner. The protein interacted with different signaling partners playing variety functions in human tissues. Interacting with its receptor complexes, signaling cascades of different pathways were activated and promoted mediating cells proliferation, differentiation, apoptosis and motility. In this paper, we will review the biological characteristics, and gene expression, regulation, signal ligands and the physiological functions and relationship with human tumors of PTPIP51.

  5. Aromatic interactions impact ligand binding and function at serotonin 5-HT2C G protein-coupled receptors: receptor homology modelling, ligand docking, and molecular dynamics results validated by experimental studies

    Córdova-Sintjago, Tania; Villa, Nancy; Fang, Lijuan; Booth, Raymond G.

    2014-02-01

    The serotonin (5-hydroxytryptamine, 5-HT) 5-HT2 G protein-coupled receptor (GPCR) family consists of types 2A, 2B, and 2C that share ∼75% transmembrane (TM) sequence identity. Agonists for 5-HT2C receptors are under development for psychoses; whereas, at 5-HT2A receptors, antipsychotic effects are associated with antagonists - in fact, 5-HT2A agonists can cause hallucinations and 5-HT2B agonists cause cardiotoxicity. It is known that 5-HT2A TM6 residues W6.48, F6.51, and F6.52 impact ligand binding and function; however, ligand interactions with these residues at the 5-HT2C receptor have not been reported. To predict and validate molecular determinants for 5-HT2C-specific activation, results from receptor homology modelling, ligand docking, and molecular dynamics simulation studies were compared with experimental results for ligand binding and function at wild type and W6.48A, F6.51A, and F6.52A point-mutated 5-HT2C receptors.

  6. Revisiting histidine-dependent acid phosphatases: a distinct group of tyrosine phosphatases

    Veeramani, Suresh; Lee, Ming-Shyue; Lin, Ming-Fong

    2009-01-01

    Although classical protein tyrosine phosphatase (PTP) superfamily members are cysteine-dependent, emerging evidence shows that many acid phosphatases (AcPs) function as histidine-dependent PTPs in vivo. These AcPs dephosphorylate phospho-tyrosine substrates intracellularly and could have roles in development and disease. In contrast to cysteine-dependent PTPs, they utilize histidine, rather than cysteine, for substrate dephosphorylation. Structural analyses reveal that active site histidine, ...

  7. Down-regulation of BDNF in cell and animal models increases striatal-enriched protein tyrosine phosphatase 61 (STEP61 ) levels.

    Xu, Jian; Kurup, Pradeep; Azkona, Garikoitz; Baguley, Tyler D; Saavedra, Ana; Nairn, Angus C; Ellman, Jonathan A; Pérez-Navarro, Esther; Lombroso, Paul J

    2016-01-01

    Brain-derived neurotrophic factor (BDNF) regulates synaptic strengthening and memory consolidation, and altered BDNF expression is implicated in a number of neuropsychiatric and neurodegenerative disorders. BDNF potentiates N-methyl-D-aspartate receptor function through activation of Fyn and ERK1/2. STriatal-Enriched protein tyrosine Phosphatase (STEP) is also implicated in many of the same disorders as BDNF but, in contrast to BDNF, STEP opposes the development of synaptic strengthening. STEP-mediated dephosphorylation of the NMDA receptor subunit GluN2B promotes internalization of GluN2B-containing NMDA receptors, while dephosphorylation of the kinases Fyn, Pyk2, and ERK1/2 leads to their inactivation. Thus, STEP and BDNF have opposing functions. In this study, we demonstrate that manipulation of BDNF expression has a reciprocal effect on STEP61 levels. Reduced BDNF signaling leads to elevation of STEP61 both in BDNF(+/-) mice and after acute BDNF knockdown in cortical cultures. Moreover, a newly identified STEP inhibitor reverses the biochemical and motor abnormalities in BDNF(+/-) mice. In contrast, increased BDNF signaling upon treatment with a tropomyosin receptor kinase B agonist results in degradation of STEP61 and a subsequent increase in the tyrosine phosphorylation of STEP substrates in cultured neurons and in mouse frontal cortex. These findings indicate that BDNF-tropomyosin receptor kinase B signaling leads to degradation of STEP61 , while decreased BDNF expression results in increased STEP61 activity. A better understanding of the opposing interaction between STEP and BDNF in normal cognitive functions and in neuropsychiatric disorders will hopefully lead to better therapeutic strategies. Altered expression of BDNF and STEP61 has been implicated in several neurological disorders. BDNF and STEP61 are known to regulate synaptic strengthening, but in opposite directions. Here, we report that reduced BDNF signaling leads to elevation of STEP61 both in

  8. Gamma-ray irradiation induce suppression of TNF-α production via up-regulation of maitogen-activated protein kinase phosphatase-1

    Complete text of publication follows. Ionizing irradiation induces DNA damage and activates a lot of signalling pathways, such as ATM and p53, due to repair the DNA damage. On the other hand, irradiation also induces activation of extracellular signal regulated protein kinase (ERK1/2) through trans-activation of EGF receptor. However, EGF-receptor-independent signalling pathways induced by irradiation are unclear. Here, we studied gamma-ray irradiation-induced signaling pathways focusing mitogen-activated kinase (MAPK), such as ERK1/2 and p38 MAPK in human keratinocyte HaCat cells, which express EGF receptor, and mouse macrophage RAW264.7 cells, which express EGF receptor at low level. These cells were irradiated by gamma-ray (0.05-2.5 Gy) from 137Cs source (0.96 Gy/min), and phosphorylated MAPKs were detected by immune blotting. Gamma-ray irradiation (0.1- 2.5Gy) induced phosphorylation of ERK1/2 in HaCat cells. However, dephosphorylation of p38 MAPK was occurred 15 min after the irradiation, indicating activation of MAPK phosphatase (MKP). On the other hand, dephosphorylation of not only p38 MAPK but also ERK1/2 were induced 15 min after irradiation (0.5 Gy) in RAW264.7 cells. At the same time point, expression of MKP-1, which dephosphorylates ERK1/2 and p38 MAPK, was significantly increased. Up-regulation of MKP-1 and dephosphorylation of p38 MAPK were also observed in irradiated mouse peritoneal macrophage. Because phosphorylation of p38 MAPK mediates pro-inflammatory cytokines, such as TNF-α , we examined the change in production of TNF-α after irradiation. Production of TNF-α was suppressed in 0.5 Gy irradiated RAW264.7 cells. In conclusion, our results suggest that gamma-ray irradiation induces up-regulation of MKP-1, leading to dephosphorylation of p38 MAPK and suppression of TNF-α production in RAW264.7cells, though ERK1/2 is activated through activation of EGF receptor in HaCat cells.

  9. Change of glutamic acid decarboxylase antibody and protein tyrosine phosphatase antibody in Chinese patients with acute-onset type 1 diabetes mellitus

    CHAO Chen; HUANG Gan; LI Xia; YANG Lin; LIN Jian; JIN Ping; LUO Shuo-ming

    2013-01-01

    Background Glutamic acid decarboxylase antibody (GADA) and protein tyrosine phosphatase antibody (IA-2A) are two major autoantibodies,which exert important roles in the process of type 1 diabetes mellitus (T1D).Our study aimed to investigate the changes in positivity and titers of GADA and IA-2A during the course of Chinese acute-onset T1D patients and their relationships with clinical features.Methods Two hundreds and forty-seven Chinese newly diagnosed acute-onset T1D patients were consecutively recruited.GADA and IA-2A were detected at the time of diagnosis,one year later,3-5 years later after diagnosis during the follow-up; all the clinical data were recorded and analyzed as well.Results During the course of acute-onset T1D,the majority of patients remained stable for GADA or IA-2A,however,a few patients changed from positivity to negativity and fewer patients converted from negativity to positivity.The prevalence of GADA was 56.3% at diagnosis,decreasing to 50.5% one year later,and 43.3% 3-5 years later while the corresponding prevalence of IA-2A were 32.8%,31.0% and 23.3%,respectively.The median GADA titers were 0.0825 at diagnosis,declining to 0.0585 one year later and 0.0383 3-5 years later (P <0.001),while the corresponding median titers were 0.0016,0.0010,0.0014 for IA-2A,respectively.Fasting C-peptide (FCP) and postprandial C-peptide 2 hours (PCP2h)levels of GADA or IA-2A negativity persistence patients were higher than those of positivity persistence and negativity conversion patients (P <0.05) which indicated GADA or IA-2A negativity persistence T1D patients had a less loss of β cell function.Conclusion Our data suggest that repeated detection of GADA and IA-2A are necessary for differential diagnosis of autoimmune diabetes and the indirect prediction of the β cell function in Chinese patients.

  10. Crystal structure of the karyopherin Kap121p bound to the extreme C-terminus of the protein phosphatase Cdc14p

    Kobayashi, Junya [Division of Biological Science, Graduate School of Science, Nagoya University (Japan); Hirano, Hidemi [Division of Biological Science, Graduate School of Science, Nagoya University (Japan); Structural Biology Research Center, Graduate School of Science, Nagoya University (Japan); Matsuura, Yoshiyuki, E-mail: matsuura.yoshiyuki@d.mbox.nagoya-u.ac.jp [Division of Biological Science, Graduate School of Science, Nagoya University (Japan); Structural Biology Research Center, Graduate School of Science, Nagoya University (Japan)

    2015-07-31

    In Saccharomyces cerevisiae, the protein phosphatase Cdc14p is an antagonist of mitotic cyclin-dependent kinases and is a key regulator of late mitotic events such as chromosome segregation, spindle disassembly and cytokinesis. The activity of Cdc14p is controlled by cell-cycle dependent changes in its association with its competitive inhibitor Net1p (also known as Cfi1p) in the nucleolus. For most of the cell cycle up to metaphase, Cdc14p is sequestered in the nucleolus in an inactive state. During anaphase, Cdc14p is released from Net1p, spreads into the nucleus and cytoplasm, and dephosphorylates key mitotic targets. Although regulated nucleocytoplasmic shuttling of Cdc14p has been suggested to be important for exit from mitosis, the mechanism underlying Cdc14p nuclear trafficking remains poorly understood. Here we show that the C-terminal region (residues 517–551) of Cdc14p can function as a nuclear localization signal (NLS) in vivo and also binds to Kap121p (also known as Pse1p), an essential nuclear import carrier in yeast, in a Gsp1p-GTP-dependent manner in vitro. Moreover we report a crystal structure, at 2.4 Å resolution, of Kap121p bound to the C-terminal region of Cdc14p. The structure and structure-based mutational analyses suggest that either the last five residues at the extreme C-terminus of Cdc14p (residues 547–551; Gly-Ser-Ile-Lys-Lys) or adjacent residues with similar sequence (residues 540–544; Gly-Gly-Ile-Arg-Lys) can bind to the NLS-binding site of Kap121p, with two residues (Ile in the middle and Lys at the end of the five residues) of Cdc14p making key contributions to the binding specificity. Based on comparison with other structures of Kap121p-ligand complexes, we propose “IK-NLS” as an appropriate term to refer to the Kap121p-specific NLS. - Highlights: • The C-terminus of Cdc14p binds to Kap121p in a Gsp1p-GTP-dependent manner. • The crystal structure of Kap121p-Cdc14p complex is determined. • The structure reveals how

  11. Deletion of Protein Tyrosine Phosphatase 1B (PTP1B Enhances Endothelial Cyclooxygenase 2 Expression and Protects Mice from Type 1 Diabetes-Induced Endothelial Dysfunction.

    David J Herren

    Full Text Available Protein tyrosine phosphatase 1B (PTP1B dephosphorylates receptors tyrosine kinase and acts as a molecular brake on insulin signaling pathway. Conditions of metabolic dysfunction increase PTP1B, when deletion of PTP1B protects against metabolic disorders by increasing insulin signaling. Although vascular insulin signaling contributes to the control of glucose disposal, little is known regarding the direct role of PTP1B in the control of endothelial function. We hypothesized that metabolic dysfunctions increase PTP1B expression in endothelial cells and that PTP1B deletion prevents endothelial dysfunction in situation of diminished insulin secretion. Type I diabetes (T1DM was induced in wild-type (WT and PTP1B-deficient mice (KO with streptozotocin (STZ injection. After 28 days of T1DM, KO mice exhibited a similar reduction in body weight and plasma insulin levels and a comparable increase in glycemia (WT: 384 ± 20 vs. Ko: 432 ± 29 mg/dL, cholesterol and triglycerides, as WT mice. T1DM increased PTP1B expression and impaired endothelial NO-dependent relaxation, in mouse aorta. PTP1B deletion did not affect baseline endothelial function, but preserved endothelium-dependent relaxation, in T1DM mice. NO synthase inhibition with L-NAME abolished endothelial relaxation in control and T1DM WT mice, whereas L-NAME and the cyclooxygenases inhibitor indomethacin were required to abolish endothelium relaxation in T1DM KO mice. PTP1B deletion increased COX-2 expression and PGI2 levels, in mouse aorta and plasma respectively, in T1DM mice. In parallel, simulation of diabetic conditions increased PTP1B expression and knockdown of PTP1B increased COX-2 but not COX-1 expression, in primary human aortic endothelial cells. Taken together these data indicate that deletion of PTP1B protected endothelial function by compensating the reduction in NO bioavailability by increasing COX-2-mediated release of the vasodilator prostanoid PGI2, in T1DM mice.

  12. Crystal structure of the karyopherin Kap121p bound to the extreme C-terminus of the protein phosphatase Cdc14p

    In Saccharomyces cerevisiae, the protein phosphatase Cdc14p is an antagonist of mitotic cyclin-dependent kinases and is a key regulator of late mitotic events such as chromosome segregation, spindle disassembly and cytokinesis. The activity of Cdc14p is controlled by cell-cycle dependent changes in its association with its competitive inhibitor Net1p (also known as Cfi1p) in the nucleolus. For most of the cell cycle up to metaphase, Cdc14p is sequestered in the nucleolus in an inactive state. During anaphase, Cdc14p is released from Net1p, spreads into the nucleus and cytoplasm, and dephosphorylates key mitotic targets. Although regulated nucleocytoplasmic shuttling of Cdc14p has been suggested to be important for exit from mitosis, the mechanism underlying Cdc14p nuclear trafficking remains poorly understood. Here we show that the C-terminal region (residues 517–551) of Cdc14p can function as a nuclear localization signal (NLS) in vivo and also binds to Kap121p (also known as Pse1p), an essential nuclear import carrier in yeast, in a Gsp1p-GTP-dependent manner in vitro. Moreover we report a crystal structure, at 2.4 Å resolution, of Kap121p bound to the C-terminal region of Cdc14p. The structure and structure-based mutational analyses suggest that either the last five residues at the extreme C-terminus of Cdc14p (residues 547–551; Gly-Ser-Ile-Lys-Lys) or adjacent residues with similar sequence (residues 540–544; Gly-Gly-Ile-Arg-Lys) can bind to the NLS-binding site of Kap121p, with two residues (Ile in the middle and Lys at the end of the five residues) of Cdc14p making key contributions to the binding specificity. Based on comparison with other structures of Kap121p-ligand complexes, we propose “IK-NLS” as an appropriate term to refer to the Kap121p-specific NLS. - Highlights: • The C-terminus of Cdc14p binds to Kap121p in a Gsp1p-GTP-dependent manner. • The crystal structure of Kap121p-Cdc14p complex is determined. • The structure reveals how

  13. Gene and protein expression and cellular localisation of cytochrome P450 enzymes of the 1A, 2A, 2C, 2D and 2E subfamilies in equine intestine and liver

    Tydén, Eva; Tjälve, Hans; Larsson, Pia

    2014-01-01

    Background Among the cytochrome P450 enzymes (CYP), families 1–3 constitute almost half of total CYPs in mammals and play a central role in metabolism of a wide range of pharmaceuticals. This study investigated gene and protein expression and cellular localisation of CYP1A, CYP2A, CYP2C, CYP2D and CYP2E in equine intestine and liver. Real-time polymerase chain reaction (RT-PCR) was used to analyse gene expression, western blot to examine protein expression and immunohistochemical analyses to ...

  14. Expression of a gibberellin-induced leucine-rich repeat receptor-like protein kinase in deepwater rice and its interaction with kinase-associated protein phosphatase.

    van der Knaap, E.; Song, W. Y.; Ruan, D L; Sauter, M.; Ronald, P C; Kende, H.

    1999-01-01

    We identified in deepwater rice (Oryza sativa L.) a gene encoding a leucine-rich repeat receptor-like transmembrane protein kinase, OsTMK (O. sativa transmembrane kinase). The transcript levels of OsTMK increased in the rice internode in response to gibberellin. Expression of OsTMK was especially high in regions undergoing cell division and elongation. The kinase domain of OsTMK was enzymatically active, autophosphorylating on serine and threonine residues. A cDNA encoding a rice ortholog of ...

  15. Induction of p53-Independent Apoptosis by the Adenovirus E4orf4 Protein Requires Binding to the Bα Subunit of Protein Phosphatase 2A

    Marcellus, Richard C.; Chan, Helen; Paquette, Denis; Thirlwell, Sarah; Boivin, Dominique; Branton, Philip E.

    2000-01-01

    Previous studies have indicated that the E4orf4 protein of human adenovirus type 2 (Ad2) induces p53-independent apoptosis. We believe that this process may play a role in cell death and viral spread at the final stages of productive infection. E4orf4 may also be of therapeutic value in treating some diseases, including cancer, through its ability to induce apoptosis when expressed individually. The only previously identified biochemical function of E4orf4 is its ability to associate with the...

  16. Development and validation of a prokaryotically expressed foot-and-mouth disease virus non-structural protein 2C'3AB-based immunochromatographic strip to differentiate between infected and vaccinated animals

    Liu Xiang-Tao

    2011-04-01

    Full Text Available Abstract Background Foot-and-mouth disease (FMD is an extremely contagious viral disease of cattle, pigs, sheep, goats, and many cloven-hoofed wild animals. FMDV serotypes O and Asia 1 have circulated separately in China during the last fifty years, and eliminating infected animals and vaccination are the main policies to prevent and control FMD. Antibodies to NSPs exist in infected animals, and were utilized to differentiate between infected and vaccinated animals. The reliability of detection of 3AB or 3ABC antibodies is higher than that of other NSPs. The test of 3AB is still credible because 3C protein's immunogenicity is the weakest. The 2C protein, immediately N-terminal of 3AB, was used to differentiate between infected and vaccinated animals. The use of the immunochromatographic strip is facile for clinical laboratories lacking specialized equipment and for rapid field diagnosis. Results In this study, an immunochromatographic strip with non-structural protein (NSP 2C'3AB was developed and validated to differentiate foot-and-mouth disease infected from vaccinated animals. A part of N-terminal of 2C protein gene and whole 3AB gene were connected and prokaryotically expressed as the antigens labeled with colloidal gold was used as the detector, the 2C'3AB protein and rabbits anti-2C'3AB antibodies were blotted on the nitrocellulose(NC membrane for the test and control lines, respectively. 387 serum samples were collected to evaluate the characteristics of the strip in comparison with existing commercial 3ABC antibody ELISA kit. The coincidence rate of pigs negative serum, pigs vaccinated serum, pigs infected serum was 100%, 97.2%, 95.0%, respectively. The coincidence rate of cattle negative serum, cattle vaccinated serum, cattle infected serum was 100%, 96.7%, 98.0%, respectively. The coincidence rate of sheep negative serum, sheep infected serum was 97.6%, 96.3%, respectively. The strip was shown to be of high specificity and sensitivity

  17. Allosteric inhibition of SHP2 phosphatase inhibits cancers driven by receptor tyrosine kinases.

    Chen, Ying-Nan P; LaMarche, Matthew J; Chan, Ho Man; Fekkes, Peter; Garcia-Fortanet, Jorge; Acker, Michael G; Antonakos, Brandon; Chen, Christine Hiu-Tung; Chen, Zhouliang; Cooke, Vesselina G; Dobson, Jason R; Deng, Zhan; Fei, Feng; Firestone, Brant; Fodor, Michelle; Fridrich, Cary; Gao, Hui; Grunenfelder, Denise; Hao, Huai-Xiang; Jacob, Jaison; Ho, Samuel; Hsiao, Kathy; Kang, Zhao B; Karki, Rajesh; Kato, Mitsunori; Larrow, Jay; La Bonte, Laura R; Lenoir, Francois; Liu, Gang; Liu, Shumei; Majumdar, Dyuti; Meyer, Matthew J; Palermo, Mark; Perez, Lawrence; Pu, Minying; Price, Edmund; Quinn, Christopher; Shakya, Subarna; Shultz, Michael D; Slisz, Joanna; Venkatesan, Kavitha; Wang, Ping; Warmuth, Markus; Williams, Sarah; Yang, Guizhi; Yuan, Jing; Zhang, Ji-Hu; Zhu, Ping; Ramsey, Timothy; Keen, Nicholas J; Sellers, William R; Stams, Travis; Fortin, Pascal D

    2016-07-01

    The non-receptor protein tyrosine phosphatase SHP2, encoded by PTPN11, has an important role in signal transduction downstream of growth factor receptor signalling and was the first reported oncogenic tyrosine phosphatase. Activating mutations of SHP2 have been associated with developmental pathologies such as Noonan syndrome and are found in multiple cancer types, including leukaemia, lung and breast cancer and neuroblastoma. SHP2 is ubiquitously expressed and regulates cell survival and proliferation primarily through activation of the RAS–ERK signalling pathway. It is also a key mediator of the programmed cell death 1 (PD-1) and B- and T-lymphocyte attenuator (BTLA) immune checkpoint pathways. Reduction of SHP2 activity suppresses tumour cell growth and is a potential target of cancer therapy. Here we report the discovery of a highly potent (IC50 = 0.071 μM), selective and orally bioavailable small-molecule SHP2 inhibitor, SHP099, that stabilizes SHP2 in an auto-inhibited conformation. SHP099 concurrently binds to the interface of the N-terminal SH2, C-terminal SH2, and protein tyrosine phosphatase domains, thus inhibiting SHP2 activity through an allosteric mechanism. SHP099 suppresses RAS–ERK signalling to inhibit the proliferation of receptor-tyrosine-kinase-driven human cancer cells in vitro and is efficacious in mouse tumour xenograft models. Together, these data demonstrate that pharmacological inhibition of SHP2 is a valid therapeutic approach for the treatment of cancers. PMID:27362227

  18. The regulatory beta-subunit of protein kinase CK2 accelerates the degradation of CDC25A phosphatase through the checkpoint kinase Chk1

    Kreutzer, Jan Nicolas; Guerra, Barbara

    2007-01-01

    Human CDC25 phosphatases play an important role in cell cycle regulation by removing inhibitory phosphate groups on cyclin-CDKs. Chk1 has been shown to phosphorylate CDC25 family members down-regulating their phosphatase activity through distinct mechanisms. The kinase activity of Chk1 is evident...... cell cycle progression is shown to enhance CDC25A degradation, and this occurs in a manner similar to that by which CDC25A is down-regulated upon activation of cellular checkpoint responses. By using RNA interference to specifically deplete cells of Chk1, we demonstrate that Chk1 mediates the down-regulation...... cell cycle regulation and indicate the mechanism by which CDC25A turnover might be regulated by Chk1 in the absence of DNA damage....

  19. Mechanical stimulation of C2C12 cells increases m-calpain expression, focal adhesion plaque protein degradation and cell differentiation

    Grossi, Alberto; Lawson, Moira Ann

    documented and has been shown to affect transcription of specific gene sequences, protein synthesis, the immune system and increase in Ca2+ influx. The past 10 years has seen a dramatic increase in the understanding of how proteolytic enzymes such as calpains can affect the growth of muscle. In vivo studies...

  20. Cdc14 phosphatase

    Machín, Félix; Quevedo Rodriguez, Oliver; Ramos-Pérez, Cristina;

    2016-01-01

    Cycling events in nature start and end to restart again and again. In the cell cycle, whose purpose is to become two where there was only one, cyclin-dependent kinases (CDKs) are the beginning and, therefore, phosphatases must play a role in the ending. Since CDKs are drivers of the cell cycle...

  1. Lipoprotein-Associated Phospholipase A2, C-Reactive Protein, and Coronary Artery Disease in Individuals with Type 1 Diabetes and Macroalbuminuria

    Miller, Rachel G.; Costacou, Tina; Orchard, Trevor J.

    2009-01-01

    Given the paucity of data in type 1 diabetes concerning lipoprotein-associated phospholipase A2 (Lp-PLA2), we examined its prospective relationship with coronary artery disease (CAD), as well as effect modification by C-reactive protein (CRP) and haptoglobin genotype, in individuals with type 1 diabetes who are at an increased risk for CAD due to also having macroalbuminuria (n=96).

  2. Atomic resolution crystal structure of VcLMWPTP-1 from Vibrio cholerae O395: Insights into a novel mode of dimerization in the low molecular weight protein tyrosine phosphatase family

    Highlights: • VcLMWPTP-1 forms dimer in solution. • The dimer is catalytically active unlike other reported dimeric LMWPTPs. • The formation of extended dimeric surface excludes the active site pocket. • The surface bears closer resemblance to eukaryotic LMWPTPs. - Abstract: Low molecular weight protein tyrosine phosphatase (LMWPTP) is a group of phosphotyrosine phosphatase ubiquitously found in a wide range of organisms ranging from bacteria to mammals. Dimerization in the LMWPTP family has been reported earlier which follows a common mechanism involving active site residues leading to an enzymatically inactive species. Here we report a novel form of dimerization in a LMWPTP from Vibrio cholera 0395 (VcLMWPTP-1). Studies in solution reveal the existence of the dimer in solution while kinetic study depicts the active form of the enzyme. This indicates that the mode of dimerization in VcLMWPTP-1 is different from others where active site residues are not involved in the process. A high resolution (1.45 Å) crystal structure of VcLMWPTP-1 confirms a different mode of dimerization where the active site is catalytically accessible as evident by a tightly bound substrate mimicking ligand, MOPS at the active site pocket. Although being a member of a prokaryotic protein family, VcLMWPTP-1 structure resembles very closely to LMWPTP from a eukaryote, Entamoeba histolytica. It also delineates the diverse surface properties around the active site of the enzyme

  3. Atomic resolution crystal structure of VcLMWPTP-1 from Vibrio cholerae O395: Insights into a novel mode of dimerization in the low molecular weight protein tyrosine phosphatase family

    Nath, Seema; Banerjee, Ramanuj; Sen, Udayaditya, E-mail: udayaditya.sen@saha.ac.in

    2014-07-18

    Highlights: • VcLMWPTP-1 forms dimer in solution. • The dimer is catalytically active unlike other reported dimeric LMWPTPs. • The formation of extended dimeric surface excludes the active site pocket. • The surface bears closer resemblance to eukaryotic LMWPTPs. - Abstract: Low molecular weight protein tyrosine phosphatase (LMWPTP) is a group of phosphotyrosine phosphatase ubiquitously found in a wide range of organisms ranging from bacteria to mammals. Dimerization in the LMWPTP family has been reported earlier which follows a common mechanism involving active site residues leading to an enzymatically inactive species. Here we report a novel form of dimerization in a LMWPTP from Vibrio cholera 0395 (VcLMWPTP-1). Studies in solution reveal the existence of the dimer in solution while kinetic study depicts the active form of the enzyme. This indicates that the mode of dimerization in VcLMWPTP-1 is different from others where active site residues are not involved in the process. A high resolution (1.45 Å) crystal structure of VcLMWPTP-1 confirms a different mode of dimerization where the active site is catalytically accessible as evident by a tightly bound substrate mimicking ligand, MOPS at the active site pocket. Although being a member of a prokaryotic protein family, VcLMWPTP-1 structure resembles very closely to LMWPTP from a eukaryote, Entamoeba histolytica. It also delineates the diverse surface properties around the active site of the enzyme.

  4. Endogenous 5-HT2C Receptors Phosphorylate the cAMP Response Element Binding Protein via Protein Kinase C-Promoted Activation of Extracellular-Regulated Kinases-1/2 in Hypothalamic mHypoA-2/10 Cells.

    Lauffer, Lisa; Glas, Evi; Gudermann, Thomas; Breit, Andreas

    2016-07-01

    Serotonin 5-HT2C receptors (5-HT2CR) activate Gq proteins and are expressed in the central nervous system (CNS). 5-HT2CR regulate emotion, feeding, reward, or cognition and may serve as promising drug targets to treat psychiatric disorders or obesity. Owing to technical difficulties in isolating cells from the CNS and the lack of suitable cell lines endogenously expressing 5-HT2CR, our knowledge about this receptor subtype in native environments is rather limited. The hypothalamic mHypoA-2/10 cell line was recently established and resembles appetite-regulating hypothalamic neurons of the paraventricular nucleus (PVN), where 5-HT2CR have been detected in vivo. Therefore, we tested mHypoA-2/10 cells for endogenous 5-HT2CR expression. Serotonin or the 5-HT2CR preferential agonist WAY-161,503 initiated cAMP response element (CRE)-dependent gene transcription with EC50 values of 15.5 ± 9.8 and 1.1 ± 0.9 nM, respectively. Both responses were blocked by two unrelated 5-HT2CR-selective antagonists (SB-242,084, RS-102,221) but not by a 5-HT2AR (EMD-281,014) or 5-HT2BR (RS-127,455) antagonists. By single-cell calcium imaging, we found that serotonin and WAY-161,503 induced robust calcium transients, which were also blunted by both 5-HT2CR antagonists. Additionally we revealed, first, that 5-HT2CR induced CRE activation via protein kinase C (PKC)-mediated engagement of extracellular-regulated kinases-1/2 and, second, that intrinsic activity of WAY-161,503 was in the range of 0.3-0.5 compared with serotonin, defining the frequently used 5-HT2CR agonist as a partial agonist of endogenous 5-HT2CR. In conclusion, we have shown that hypothalamic mHypoA-2/10 cells endogenously express 5-HT2CR and thus are the first cell line in which to analyze 5-HT2CR pharmacology, signaling, and regulation in its natural environment. PMID:27189964

  5. Identification of a naturally processed cytotoxic CD8 T-cell epitope of coxsackievirus B4, presented by HLA-A2.1 and located in the PEVKEK region of the P2C nonstructural protein.

    Varela-Calvino, Ruben; Skowera, Ania; Arif, Sefina; Peakman, Mark

    2004-12-01

    The adaptive immune system generates CD8 cytotoxic T lymphocytes (CTLs) as a major component of the protective response against viruses. Knowledge regarding the nature of the peptide sequences presented by HLA class I molecules and recognized by CTLs is thus important for understanding host-pathogen interactions. In this study, we focused on identification of a CTL epitope generated from coxsackievirus B4 (CVB4), a member of the enterovirus group responsible for several inflammatory diseases in humans and often implicated in the triggering and/or acceleration of the autoimmune disease type 1 diabetes. We identified a 9-mer peptide epitope that can be generated from the P2C nonstructural protein of CVB4 (P2C(1137-1145)) and from whole virus by antigen-presenting cells and presented by HLA-A2.1. This epitope is recognized by effector memory (gamma interferon [IFN-gamma]-producing) CD8 T cells in the peripheral blood at a frequency of responders that suggests that it is a major focus of the anti-CVB4 response. Short-term CD8 T-cell lines generated against P2C(1137-1145) are cytotoxic against peptide-loaded target cells. Of particular interest, the epitope lies within a region of viral homology with the diabetes-related autoantigen, glutamic acid decarboxylase-65 (GAD(65)). However, P2C(1137-1145)-specific cytotoxic T lymphocyte (CTL) lines were not activated to produce IFN-gamma by the GAD(65) peptide homologue and did not show cytotoxic activity in the presence of appropriately labeled targets. These results describe the first CD8 T-cell epitope of CVB4 that will prove useful in the study of CVB4-associated disease. PMID:15564450

  6. Evaluation of the Staphylococcus aureus Class C Nonspecific Acid Phosphatase (SapS) as a Reporter for Gene Expression and Protein Secretion in Gram-Negative and Gram-Positive Bacteria▿

    Du Plessis, Erika; Theron, Jacques; Berger, Eldie; Louw, Maureen

    2007-01-01

    A phosphatase secreted by Staphylococcus aureus strain 154 has previously been characterized and classified as a new member of the bacterial class C family of nonspecific acid phosphatases. As the acid phosphatase activity can be easily detected with a cost-effective plate screen assay, quantitatively measured by a simple enzyme assay, and detected by zymography, its potential use as a reporter system was investigated. The S. aureus acid phosphatase (sapS) gene has been cloned and expressed f...

  7. Fad24, a Positive Regulator of Adipogenesis, Is Required for S Phase Re-entry of C2C12 Myoblasts Arrested in G0 Phase and Involved in p27(Kip1) Expression at the Protein Level.

    Ochiai, Natsuki; Nishizuka, Makoto; Osada, Shigehiro; Imagawa, Masayoshi

    2016-05-01

    Factor for adipocyte differentiation 24 (fad24) is a positive regulator of adipogenesis. We previously found that human fad24 is abundantly expressed in skeletal muscle. However, the function of fad24 in skeletal muscle remains largely unknown. Because skeletal muscle is a highly regenerative tissue, we focused on the function of fad24 in skeletal muscle regeneration. In this paper, we investigated the role of fad24 in the cell cycle re-entry of quiescent C2C12 myoblasts-mimicked satellite cells. The expression levels of fad24 and histone acetyltransferase binding to ORC1 (hbo1), a FAD24-interacting factor, were elevated at the early phase of the regeneration process in response to cardiotoxin-induced muscle injury. The knockdown of fad24 inhibited the proliferation of quiescent myoblasts, whereas fad24 knockdown did not affect differentiation. S phase entry following serum activation is abrogated by fad24 knockdown in quiescent cells. Furthermore, fad24 knockdown cells show a marked accumulation of p27(Kip1) protein. These results suggest that fad24 may have an important role in the S phase re-entry of quiescent C2C12 cells through the regulation of p27(Kip1) at the protein level. PMID:26902224

  8. Optimization of a Cyclic Peptide Inhibitor of Ser/Thr Phosphatase PPM1D (Wip1)†

    Hayashi, Ryo; Tanoue, Kan; Durell, Stewart R; Chatterjee, Deb K.; Miller Jenkins, Lisa M.; Appella, Daniel H.; Appella, Ettore

    2011-01-01

    PPM1D (PP2Cδ or Wip1) was identified as a wild type p53-induced Ser/Thr phosphatase that accumulates after DNA damage and classified into the PP2C family. It dephosphorylates and inactivates several proteins critical for cellular stress responses, including p38 MAPK, p53, and ATM. Furthermore, PPM1D is amplified and/or overexpressed in a number of human cancers. Thus, inhibition of its activity could constitute an important new strategy for therapeutic intervention to halt the progression of ...

  9. Direct determination of phosphatase activity from physiological substrates in cells.

    Zhongyuan Ren

    Full Text Available A direct and continuous approach to determine simultaneously protein and phosphate concentrations in cells and kinetics of phosphate release from physiological substrates by cells without any labeling has been developed. Among the enzymes having a phosphatase activity, tissue non-specific alkaline phosphatase (TNAP performs indispensable, multiple functions in humans. It is expressed in numerous tissues with high levels detected in bones, liver and neurons. It is absolutely required for bone mineralization and also necessary for neurotransmitter synthesis. We provided the proof of concept that infrared spectroscopy is a reliable assay to determine a phosphatase activity in the osteoblasts. For the first time, an overall specific phosphatase activity in cells was determined in a single step by measuring simultaneously protein and substrate concentrations. We found specific activities in osteoblast like cells amounting to 116 ± 13 nmol min(-1 mg(-1 for PPi, to 56 ± 11 nmol min(-1 mg(-1 for AMP, to 79 ± 23 nmol min(-1 mg(-1 for beta-glycerophosphate and to 73 ± 15 nmol min(-1 mg(-1 for 1-alpha-D glucose phosphate. The assay was also effective to monitor phosphatase activity in primary osteoblasts and in matrix vesicles. The use of levamisole--a TNAP inhibitor--served to demonstrate that a part of the phosphatase activity originated from this enzyme. An IC50 value of 1.16 ± 0.03 mM was obtained for the inhibition of phosphatase activity of levamisole in osteoblast like cells. The infrared assay could be extended to determine any type of phosphatase activity in other cells. It may serve as a metabolomic tool to monitor an overall phosphatase activity including acid phosphatases or other related enzymes.

  10. Structural mechanisms of plant glucan phosphatases in starch metabolism.

    Meekins, David A; Vander Kooi, Craig W; Gentry, Matthew S

    2016-07-01

    Glucan phosphatases are a recently discovered class of enzymes that dephosphorylate starch and glycogen, thereby regulating energy metabolism. Plant genomes encode two glucan phosphatases, called Starch EXcess4 (SEX4) and Like Sex Four2 (LSF2), that regulate starch metabolism by selectively dephosphorylating glucose moieties within starch glucan chains. Recently, the structures of both SEX4 and LSF2 were determined, with and without phosphoglucan products bound, revealing the mechanism for their unique activities. This review explores the structural and enzymatic features of the plant glucan phosphatases, and outlines how they are uniquely adapted to perform their cellular functions. We outline the physical mechanisms used by SEX4 and LSF2 to interact with starch glucans: SEX4 binds glucan chains via a continuous glucan-binding platform comprising its dual-specificity phosphatase domain and carbohydrate-binding module, while LSF2 utilizes surface binding sites. SEX4 and LSF2 both contain a unique network of aromatic residues in their catalytic dual-specificity phosphatase domains that serve as glucan engagement platforms and are unique to the glucan phosphatases. We also discuss the phosphoglucan substrate specificities inherent to SEX4 and LSF2, and outline structural features within the active site that govern glucan orientation. This review defines the structural mechanism of the plant glucan phosphatases with respect to phosphatases, starch metabolism and protein-glucan interaction, thereby providing a framework for their application in both agricultural and industrial settings. PMID:26934589

  11. Research progress of relationship between protein tyrosine phosphatase 1B and hematologic neoplasms%蛋白酪氨酸磷酸酶1B与血液系统肿瘤关系研究进展

    李冰; 周莉莉; 傅建非

    2015-01-01

    酪氨酸磷酸化是一种重要的调节细胞进程和维持稳态的翻译后修饰,酪氨酸磷酸化的异常改变常与疾病发生如代谢障碍、肿瘤和心血管疾病等密切相关.蛋白酪氨酸磷酸酶(PTP)是在细胞增殖和信号转导过程中调节蛋白酪氨酸残基磷酸化水平的酶家族.目前研究发现人类共有1 12种PTP,其中蛋白酪氨酸磷酸酶1B(PTP1B)是该家族中研究最热、最清楚的成员之一.近年来,PTP1B作为一种积极参与肿瘤发生的酶,引起了广泛关注.现就PTP1B与血液系统肿瘤关系的研究进展进行综述.%Tyrosine phosphorylation is a key post-translational mechanism that regulates cellular processes and maintains homeostasis.Aberrant changes in tyrosine phosphorylation are often associated with disease states such as metabolicdisorders,cancer and cardiovascular disease.Protein tyrosine phosphatases (PTPs) are the enzyme family that regulates protein phosphorylation level of tyrosine residues in the cellular processes and signaling ways.So far,scientists have discovered 112 kinds of human PTPs.Among them,PTP1B is widely and clearly studied.Recently,as an enzyme that play a role in oncogenesis,PTP1B has been wildey studied by scientists.Here,we highlight the relationship between protein tyrosine phosphatase 1B and hematologic neoplasms.

  12. Complex coordinated extracellular metabolism: Acid phosphatases activate diluted human leukocyte proteins to generate energy flow as NADPH from purine nucleotide ribose.

    Hibbs, John B; Vavrin, Zdenek; Cox, James E

    2016-08-01

    Complex metabolism is thought to occur exclusively in the crowded intracellular environment. Here we report that diluted enzymes from lysed human leukocytes produce extracellular energy. Our findings involve two pathways: the purine nucleotide catabolic pathway and the pentose phosphate pathway, which function together to generate energy as NADPH. Glucose6P fuel for NADPH production is generated from structural ribose of purine ribonucleoside monophosphates, ADP, and ADP-ribose. NADPH drives glutathione reductase to reduce an oxidized glutathione disulfide-glutathione redox couple. Acid phosphatases initiate ribose5P salvage from purine ribonucleoside monophosphates, and transaldolase controls the direction of carbon chain flow through the nonoxidative branch of the pentose phosphate pathway. These metabolic control points are regulated by pH. Biologically, this energy conserving metabolism could function in perturbed extracellular spaces. PMID:26895212

  13. Low-frequency stimulation induces a durable long-term depression in young adult hyperthyroid rats: the role of p38 mitogen-activated protein kinase and protein phosphatase 1.

    Tan, Burak; Bitiktaş, Soner; Kavraal, Şehrazat; Dursun, Nurcan; Dönmez Altuntaş, Hamiyet; Suer, Cem

    2016-06-15

    Long-term potentiation and long-term depression (LTD) are cellular mechanisms of learning and memory in the mammalian brain. We have previously shown that adult hyperthyroid rats showed a delay in the acquisition of a place learning task and attenuated long-term potentiation. However, changes in LTD in hyperthyroidism remain unclear. Rats were administered 0.2 mg/kg/day of L-thyroxine for 21 days starting at postnatal day 40 to induce hyperthyroidism. LTD was induced in the dentate gyrus using low-frequency stimulation (LFS) of the perforant pathway. The mRNA expressions of p38 mitogen-activated protein kinase (p38-MAPK) and protein phosphatase 1 (PP1) were evaluated using a quantitative reverse transcriptase PCR. In control rats, a standard LFS protocol induced a slight depression of the population spike (PS) amplitude during the induction phase of LTD (76±13% vs. baseline), but a small potentiation of the PS amplitude was observed in the early (107±18%) and late (111±20%) phases of LTD. Interestingly, in the hyperthyroid rats, the same LFS protocol induced a reliable LTD in the dentate gyrus of the hippocampus as evidenced by a marked depression in the PS amplitude during the induction (54±6% vs. baseline) and the early phases (56±8%) of LTD. Elevated mRNA levels of p38-MAPK and PP1 were observed in the hippocampus of the LFS-treated hyperthyroid rats compared with the hippocampus of the vehicle-treated hyperthyroid rats. No significant change in p38-MAPK or PP1 mRNA expression was observed in the euthyroid rats. The present study shows that a standard LFS protocol can induce a durable depression of synaptic strength and an upregulation of PP1 and p38-MAPK mRNA in hyperthyroid rats. We conclude that hyperthyroidism can induce molecular changes associated with degeneration of the hippocampus. The relationship between the levels of thyroid hormone and dementia requires further investigation. PMID:27128724

  14. Alkaline Phosphatase in Stem Cells

    Kateřina Štefková

    2015-01-01

    Full Text Available Alkaline phosphatase is an enzyme commonly expressed in almost all living organisms. In humans and other mammals, determinations of the expression and activity of alkaline phosphatase have frequently been used for cell determination in developmental studies and/or within clinical trials. Alkaline phosphatase also seems to be one of the key markers in the identification of pluripotent embryonic stem as well as related cells. However, alkaline phosphatases exist in some isoenzymes and isoforms, which have tissue specific expressions and functions. Here, the role of alkaline phosphatase as a stem cell marker is discussed in detail. First, we briefly summarize contemporary knowledge of mammalian alkaline phosphatases in general. Second, we focus on the known facts of its role in and potential significance for the identification of stem cells.

  15. Modulators of intestinal alkaline phosphatase.

    Bobkova, Ekaterina V; Kiffer-Moreira, Tina; Sergienko, Eduard A

    2013-01-01

    Small molecule modulators of phosphatases can lead to clinically useful drugs and serve as invaluable tools to study functional roles of various phosphatases in vivo. Here, we describe lead discovery strategies for identification of inhibitors and activators of intestinal alkaline phosphatases. To identify isozyme-selective inhibitors and activators of the human and mouse intestinal alkaline phosphatases, ultrahigh throughput chemiluminescent assays, utilizing CDP-Star as a substrate, were developed for murine intestinal alkaline phosphatase (mIAP), human intestinal alkaline phosphatase (hIAP), human placental alkaline phosphatase (PLAP), and human tissue-nonspecific alkaline phosphatase (TNAP) isozymes. Using these 1,536-well assays, concurrent HTS screens of the MLSMR library of 323,000 compounds were conducted for human and mouse IAP isozymes monitoring both inhibition and activation. This parallel screening approach led to identification of a novel inhibitory scaffold selective for murine intestinal alkaline phosphatase. SAR efforts based on parallel testing of analogs against different AP isozymes generated a potent inhibitor of the murine IAP with IC50 of 540 nM, at least 65-fold selectivity against human TNAP, and >185 selectivity against human PLAP. PMID:23860652

  16. Leishmanial phosphatase hydrolyzes phosphoproteins and inositol phosphates

    An extensively purified preparation of the predominant, tartrate-resistant acid phosphatase (ACP) from the external surface of Leishmania donovani promastigotes form catalyzes the dephosphorylation of several phosphoproteins; these include: pyruvate kinase, phosphorylase kinase and histones. However, the protein phosphatase activity of ACP is very low compared with that of other protein phosphates known to be involved in regulating various metabolic pathways. 32P-labelled inositoltriphosphate (IP3), a well-established second messenger derived from phosphatidylinositol-4,5-diphosphate (PIP2), was a substrate for the leishmanial acid phosphatase; incubation of the IP3 preparation with 13.2 milliunits (1 unit equals 1 μmol 4-methylumbelliferyl phosphate (MUP) cleaved per min at pH 5.5) of ACP at pH 5.5 for 4 hr resulted in hydrolysis of 75% of the radiolabelled substrate resulting in a mixture of inositoldiphosphate and inositolmonophosphate. In addition PIP2 was hydrolyzed rapidly by ACP at pH 5.5 (V/sub max/, 71 units/mg protein; k/sub m/, 4.16 μM). In contrast, to MUP which is hydrolzyed most rapidly at pH 5.5, PIP2 hydrolysis was optimal at pH 6.8. These observations raise the possibility that ACP could play a role in the host-phagocyte interaction by degrading the precursor of the second messenger, PIP2 or the second messenger itself, IP3

  17. Phactr3/scapinin, a member of protein phosphatase 1 and actin regulator (phactr family, interacts with the plasma membrane via basic and hydrophobic residues in the N-terminus.

    Akihiro Itoh

    Full Text Available Proteins that belong to the protein phosphatase 1 and actin regulator (phactr family are involved in cell motility and morphogenesis. However, the mechanisms that regulate the actin cytoskeleton are poorly understood. We have previously shown that phactr3, also known as scapinin, localizes to the plasma membrane, including lamellipodia and membrane ruffles. In the present study, experiments using deletion and point mutants showed that the basic and hydrophobic residues in the N-terminus play crucial roles in the localization to the plasma membrane. A BH analysis (http://helixweb.nih.gov/bhsearch is a program developed to identify membrane-binding domains that comprise basic and hydrophobic residues in membrane proteins. We applied this program to phactr3. The results of the BH plot analysis agreed with the experimentally determined region that is responsible for the localization of phactr3 to the plasma membrane. In vitro experiments showed that the N-terminal itself binds to liposomes and acidic phospholipids. In addition, we showed that the interaction with the plasma membrane via the N-terminal membrane-binding sequence is required for phactr3-induced morphological changes in Cos7 cells. The membrane-binding sequence in the N-terminus is highly conserved in all members of the phactr family. Our findings may provide a molecular basis for understanding the mechanisms that allow phactr proteins to regulate cell morphogenesis.

  18. Phosphatidylinositol anchor of HeLa cell alkaline phosphatase

    Alkaline phosphatase from cancer cells, HeLa TCRC-1, was biosynthetically labeled with either 3H-fatty acids or [3H]ethanolamine as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material. Phosphatidylinositol-specific phospholipase C (PI-PLC) released a substantial proportion of the 3H-fatty acid label from immunoaffinity-purified alkaline phosphatase but had no effect on the radioactivity of [3H]ethanolamine-labeled material. PI-PLC also liberated catalytically active alkaline phosphatase from viable cells, and this could be selectively blocked by monoclonal antibodies to alkaline phosphatase. However, the alkaline phosphatase released from 3H-fatty acid labeled cells by PI-PLC was not radioactive. By contrast, treatment with bromelain removed both the 3H-fatty acid and the [3H]ethanolamine label from purified alkaline phosphatase. Subtilisin was also able to remove the [3H]ethanolamine label from the purified alkaline phosphatase. The 3H radioactivity in alkaline phosphatase purified from [3H]ethanolamine-labeled cells comigrated with authentic [3H]ethanolamine by anion-exchange chromatography after acid hydrolysis. The data suggest that the 3H-fatty acid and [3H]ethanolamine are covalently attached to the carboxyl-terminal segment since bromelain and subtilisin both release alkaline phosphatase from the membrane by cleavage at that end of the polypeptide chain. The data are consistent with findings for other proteins recently shown to be anchored in the membrane through a glycosylphosphatidylinositol structure and indicate that a similar structure contributes to the membrane anchoring of alkaline phosphatase

  19. Phosphatidylinositol anchor of HeLa cell alkaline phosphatase

    Jemmerson, R.; Low, M.G.

    1987-09-08

    Alkaline phosphatase from cancer cells, HeLa TCRC-1, was biosynthetically labeled with either /sup 3/H-fatty acids or (/sup 3/H)ethanolamine as analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and fluorography of immunoprecipitated material. Phosphatidylinositol-specific phospholipase C (PI-PLC) released a substantial proportion of the /sup 3/H-fatty acid label from immunoaffinity-purified alkaline phosphatase but had no effect on the radioactivity of (/sup 3/H)ethanolamine-labeled material. PI-PLC also liberated catalytically active alkaline phosphatase from viable cells, and this could be selectively blocked by monoclonal antibodies to alkaline phosphatase. However, the alkaline phosphatase released from /sup 3/H-fatty acid labeled cells by PI-PLC was not radioactive. By contrast, treatment with bromelain removed both the /sup 3/H-fatty acid and the (/sup 3/H)ethanolamine label from purified alkaline phosphatase. Subtilisin was also able to remove the (/sup 3/H)ethanolamine label from the purified alkaline phosphatase. The /sup 3/H radioactivity in alkaline phosphatase purified from (/sup 3/H)ethanolamine-labeled cells comigrated with authentic (/sup 3/H)ethanolamine by anion-exchange chromatography after acid hydrolysis. The data suggest that the /sup 3/H-fatty acid and (/sup 3/H)ethanolamine are covalently attached to the carboxyl-terminal segment since bromelain and subtilisin both release alkaline phosphatase from the membrane by cleavage at that end of the polypeptide chain. The data are consistent with findings for other proteins recently shown to be anchored in the membrane through a glycosylphosphatidylinositol structure and indicate that a similar structure contributes to the membrane anchoring of alkaline phosphatase.

  20. Primary structure of rat secretory acid phosphatase and comparison to other acid phosphatases.

    Roiko, K; Jänne, O A; Vihko, P

    1990-05-14

    Overlapping cDNA clones encoding rat prostatic acid phosphatase (rPAP) were isolated by using two human prostatic acid phosphatase (hPAP)-encoding cDNAs to screen rat prostatic cDNA libraries. The isolated cDNAs encompassed a total of 1626 nucleotides (nt), of which 1143 nt corresponded to the protein coding sequence encoding a mature polypeptide of 350 amino acids (aa) and a 31-aa long signal peptide-like sequence. The deduced Mr of the mature rPAP was 40,599. RNA blot analysis indicated the presence of three mRNA species (4.9, 2.3 and 1.5 kb in size) in the rat prostate. The deduced aa sequences of rPAP and hPAP show 75% identity, whereas the similarity between rPAP and human lysosomal acid phosphatase (hLAP) is only 45%. Furthermore, the sequence similarity between rPAP and rat lysosomal acid phosphatase (rLAP) is 46% at the aa level. Similar to hPAP, but unlike hLAP and rLAP, the rPAP sequence lacks a membrane-anchoring domain indicating the secretory character of this phosphatase. All six cysteines present in the overlapping areas of the mature rPAP, hPAP, rLAP and hLAP proteins are positionally conserved, suggesting that these residues are important for the tertiary structure of acid phosphatases (APs). The previously reported active site residues, two arginines and one histidine, are also conserved in these APs. PMID:2373368

  1. Isolation and characterization of a neutral phosphatase from wheat seedlings

    A neutral phosphatase was purified to homogeneity from wheat seedlings. The enzyme was a monomeric glycoprotein exhibiting a molecular weight of 35,000, frictional ratio of 1.22, Stokes' radius of 26 A, and sedimentation coefficient of 3.2 S. That the enzyme was a glycoprotein was surmised from its chromatographic property on Concanavalin A-Sepharose column. The phosphatase activity was assayed using either fructose-2,6-bisphosphate or p-nitrophenyl phosphate as substrate. The phosphatase activity was not affected by high concentrations of chelating agents and did not require the addition of Mg+2 or Ca+2 for its activity. Molybdate, orthovanadate, Zn+2, and Hg+2 were all potent inhibitors of the phosphatase activity. The inhibition by Hg+2 was reversed by dithiothreitol. The enzyme activity was stimulated by Mn+2 about 2-fold. On the other hand, 3-phosphoglycerate, fructose-6-P and Pi as well as polyamines inhibited the enzyme activity. The ability of the neutral phosphatase to dephosphorylate protein phosphotyrosine was also investigated. The phosphotyrosyl-substrates, such as [32P] phosphotyrosyl-poly(Glu, Tyr)n, -alkylated bovine serum albumin, -angiotensin-1, and -band 3 of erythrocytes, were all substrates of the phosphatase. On the other hand, the enzyme had no activity toward protein phosphoserine and protein phosphothreonine

  2. Expression of potato RNA-binding proteins StUBA2a/b and StUBA2c induces hypersensitive-like cell death and early leaf senescence in Arabidopsis.

    Na, Jong-Kuk; Kim, Jae-Kwang; Kim, Dool-Yi; Assmann, Sarah M

    2015-07-01

    The Arabidopsis thaliana genome encodes three RNA-binding proteins (RBPs), UBP1-associated protein 2a (UBA2a), UBA2b, and UBA2c, that contain two RNA-recognition motif (RRM) domains. They play important roles in wounding response and leaf senescence, and are homologs of Vicia faba abscisic-acid-activated protein kinase-interacting protein 1 (VfAKIP1). The potato (Solanum tuberosum) genome encodes at least seven AKIP1-like RBPs. Here, two potato RBPs have been characterized, StUBA2a/b and StUBA2c, that are homologous to VfAKIP1 and Arabidopsis UBA2s. Transient expression of StUBA2s induced a hypersensitive-like cell death phenotype in tobacco leaves, and an RRM-domain deletion assay of StUBA2s revealed that the first RRM domain is crucial for the phenotype. Unlike overexpression of Arabidopsis UBA2s, constitutive expression of StUBA2a/b in Arabidopsis did not cause growth arrest and lethality at the young seedling stage, but induced early leaf senescence. This phenotype was associated with increased expression of defence- and senescence-associated genes, including pathogen-related genes (PR) and a senescence-associated gene (SAG13), and it was aggravated upon flowering and ultimately resulted in a shortened life cycle. Leaf senescence of StUBA2a/b Arabidopsis plants was enhanced under darkness and was accompanied by H2O2 accumulation and altered expression of autophagy-associated genes, which likely cause cellular damage and are proximate causes of the early leaf senescence. Expression of salicylic acid signalling and biosynthetic genes was also upregulated in StUBA2a/b plants. Consistent with the localization of UBA2s-GFPs and VfAKIP1-GFP, soluble-modified GFP-StUBA2s localized in the nucleus within nuclear speckles. StUBA2s potentially can be considered for transgenic approaches to induce potato shoot senescence, which is desirable at harvest. PMID:25944928

  3. Expression of paired-like homeodomain transcription factor 2c (PITX2c) in epidermal keratinocytes

    Paired-like homeodomain transcription factor 2 (PITX2) has been implicated as one of the genes responsible for Rieger syndrome. It has been also shown to play a central role during development. In this study, we investigated the functional role of PITX2 in keratinocyte differentiation. RT-PCR analysis showed that PITX2c isoform was predominantly expressed in a differentiation-dependent manner. Consistent with, immunohistochemical staining showed that PITX2 expression was increased in the upper layer of epidermis. When PITX2c was overexpressed in cultured keratinocytes by a recombinant adenovirus, the differentiation markers such as involucrin and loricrin were significantly increased at both mRNA and protein levels. In addition, PITX2c overexpression led to the decrease of cell growth, concomitantly with the upregulation of cell cycle-related genes p21. To investigate the effect of PITX2c in vivo, we microinjected PITX2c expression vector into zebrafish embryo. Interestingly, overexpression of PITX2c in zebrafish embryo led to the formation of horn-like structure and thickening of epidermis, together with the increase of keratin 8 (K8) expression. These results suggest that PITX2c has a role in proliferation and differentiation of epidermal keratinocytes.

  4. Expression of paired-like homeodomain transcription factor 2c (PITX2c) in epidermal keratinocytes

    Shi, Ge [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Department of Dermatology, The First Affiliated Hospital, Guangxi Traditional Chinese Medical University, Guangxi, Nanning, 530023 (China); Sohn, Kyung-Cheol; Choi, Tae-Young; Choi, Dae-Kyoung; Lee, Sang-Sin [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Ou, Bai-sheng [Department of Dermatology, The First Affiliated Hospital, Guangxi Traditional Chinese Medical University, Guangxi, Nanning, 530023 (China); Kim, Sooil; Lee, Young Ho [Department of Anatomy, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Yoon, Tae-Jin [Department of Dermatology, School of Medicine, Gyeongsang National University, Jinju, 660-702 (Korea, Republic of); Institute of Health Sciences, School of Medicine, Gyeongsang National University, Jinju, 660-702 (Korea, Republic of); Kim, Seong-Jin [Department of Dermatology, Chonnam National University Medical School, Gwangju, 501-757 (Korea, Republic of); Lee, Young; Seo, Young-Joon; Lee, Jeung-Hoon [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Kim, Chang Deok, E-mail: cdkimd@cnu.ac.kr [Department of Dermatology, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of); Research Institute for Medical Sciences, School of Medicine, Chungnam National University, Daejeon, 301-747 (Korea, Republic of)

    2010-11-15

    Paired-like homeodomain transcription factor 2 (PITX2) has been implicated as one of the genes responsible for Rieger syndrome. It has been also shown to play a central role during development. In this study, we investigated the functional role of PITX2 in keratinocyte differentiation. RT-PCR analysis showed that PITX2c isoform was predominantly expressed in a differentiation-dependent manner. Consistent with, immunohistochemical staining showed that PITX2 expression was increased in the upper layer of epidermis. When PITX2c was overexpressed in cultured keratinocytes by a recombinant adenovirus, the differentiation markers such as involucrin and loricrin were significantly increased at both mRNA and protein levels. In addition, PITX2c overexpression led to the decrease of cell growth, concomitantly with the upregulation of cell cycle-related genes p21. To investigate the effect of PITX2c in vivo, we microinjected PITX2c expression vector into zebrafish embryo. Interestingly, overexpression of PITX2c in zebrafish embryo led to the formation of horn-like structure and thickening of epidermis, together with the increase of keratin 8 (K8) expression. These results suggest that PITX2c has a role in proliferation and differentiation of epidermal keratinocytes.

  5. Characterization and site-directed mutagenesis of Wzb, an O-phosphatase from Lactobacillus rhamnosus

    Gilbert Christophe

    2008-04-01

    Full Text Available Abstract Background Reversible phosphorylation events within a polymerisation complex have been proposed to modulate capsular polysaccharide synthesis in Streptococcus pneumoniae. Similar phosphatase and kinase genes are present in the exopolysaccharide (EPS biosynthesis loci of numerous lactic acid bacteria genomes. Results The protein sequence deduced from the wzb gene in Lactobacillus rhamnosus ATCC 9595 reveals four motifs of the polymerase and histidinol phosphatase (PHP superfamily of prokaryotic O-phosphatases. Native and modified His-tag fusion Wzb proteins were purified from Escherichia coli cultures. Extracts showed phosphatase activity towards tyrosine-containing peptides. The purified fusion protein Wzb was active on p-nitrophenyl-phosphate (pNPP, with an optimal activity in presence of bovine serum albumin (BSA 1% at pH 7.3 and a temperature of 75°C. At 50°C, residual activity decreased to 10 %. Copper ions were essential for phosphatase activity, which was significantly increased by addition of cobalt. Mutated fusion Wzb proteins exhibited reduced phosphatase activity on p-nitrophenyl-phosphate. However, one variant (C6S showed close to 20% increase in phosphatase activity. Conclusion These characteristics reveal significant differences with the manganese-dependent CpsB protein tyrosine phosphatase described for Streptococcus pneumoniae as well as with the polysaccharide-related phosphatases of Gram negative bacteria.

  6. Protein phosphatase 2A associates with Rb2/p130 and mediates retinoic acid-induced growth suppression of ovarian carcinoma cells

    Vuocolo, Scott; Purev, Enkhtsetseg; Zhang, Dongmei;

    2003-01-01

    Levels of Rb2/p130 protein are increased 5-10-fold following all-trans-retinoic acid (ATRA) treatment of the retinoid-sensitive ovarian adenocarcinoma cell line CAOV3, but not the retinoid-resistant adenocarcinoma cell line SKOV3. We found that this increase in Rb2/p130 protein levels in ATRA...

  7. Overexpression of Human Bone Alkaline Phosphatase in Pichia Pastoris

    Karr, Laurel; Malone, Christine, C.; Rose, M. Franklin (Technical Monitor)

    2000-01-01

    The Pichiapastoris expression system was utilized to produce functionally active human bone alkaline phosphatase in gram quantities. Bone alkaline phosphatase is a key enzyme in bone formation and biomineralization, yet important questions about its structural chemistry and interactions with other cellular enzymes in mineralizing tissues remain unanswered. A soluble form of human bone alkaline phosphatase was constructed by deletion of the 25 amino acid hydrophobic C-terminal region of the encoding cDNA and inserted into the X-33 Pichiapastoris strain. An overexpression system was developed in shake flasks and converted to large-scale fermentation. Alkaline phosphatase was secreted into the medium to a level of 32mgAL when cultured in shake flasks. Enzyme activity was 12U/mg measured by a spectrophotometric assay. Fermentation yielded 880mgAL with enzymatic activity of 968U/mg. Gel electrophoresis analysis indicates that greater than 50% of the total protein in the fermentation is alkaline phosphatase. A purification scheme has been developed using ammonium sulfate precipitation followed by hydrophobic interaction chromatography. We are currently screening crystallization conditions of the purified recombinant protein for subsequent X-ray diffraction analyses. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

  8. Structural Basis of Response Regulator Dephosphorylation by Rap Phosphatases

    V Parashar; N Mirouze; D Dubnau; M Neiditch

    2011-12-31

    Bacterial Rap family proteins have been most extensively studied in Bacillus subtilis, where they regulate activities including sporulation, genetic competence, antibiotic expression, and the movement of the ICEBs1 transposon. One subset of Rap proteins consists of phosphatases that control B. subtilis and B. anthracis sporulation by dephosphorylating the response regulator Spo0F. The mechanistic basis of Rap phosphatase activity was unknown. Here we present the RapH-Spo0F X-ray crystal structure, which shows that Rap proteins consist of a 3-helix bundle and a tetratricopeptide repeat domain. Extensive biochemical and genetic functional studies reveal the importance of the observed RapH-Spo0F interactions, including the catalytic role of a glutamine in the RapH 3-helix bundle that inserts into the Spo0F active site. We show that in addition to dephosphorylating Spo0F, RapH can antagonize sporulation by sterically blocking phosphoryl transfer to and from Spo0F. Our structure-function analysis of the RapH-Spo0F interaction identified Rap protein residues critical for Spo0F phosphatase activity. This information enabled us to assign Spo0F phosphatase activity to a Rap protein based on sequence alone, which was not previously possible. Finally, as the ultimate test of our newfound understanding of the structural requirements for Rap phosphatase function, a non-phosphatase Rap protein that inhibits the binding of the response regulator ComA to DNA was rationally engineered to dephosphorylate Spo0F. In addition to revealing the mechanistic basis of response regulator dephosphorylation by Rap proteins, our studies support the previously proposed T-loop-Y allostery model of receiver domain regulation that restricts the aromatic 'switch' residue to an internal position when the {beta}4-{alpha}4 loop adopts an active-site proximal conformation.

  9. Sequence of the human glycogen-associated regulatory subunit of type 1 protein phosphatase and analysis of its coding region and mRNA level in muscle from patients with NIDDM

    Chen, Y H; Hansen, L; Chen, Min;

    1994-01-01

    protein phosphatase 1 (PP1 G-subunit) plays a key role in the insulin stimulation of glycogen synthesis and the activity of PP1 is decreased in insulin-resistant subjects, we have now cloned the human G-subunit cDNA to search for abnormalities in the corresponding gene (designated PPP1R3 in the human...... genome nomenclature) in patients with NIDDM. The human cDNA was isolated from a skeletal muscle cDNA library and was found to encode a 126-kDa protein, which shows 73% amino acid identity to the rabbit PP1 G-subunit. The human G-subunit cDNA from 30 insulin-resistant NIDDM patients was analyzed for...... genetic variations in the G-subunit by using single-stranded conformation polymorphism (SSCP) scanning of reversely transcribed mRNA. One variant SSCP profile was detected in the region encoding the COOH-terminal part of the PP1 G-subunit in only one NIDDM patient, and subsequent nucleotide sequencing...

  10. ABA Signaling in Guard Cells Entails a Dynamic Protein-Protein Interaction Relay from the PYL-RCAR Family Receptors to Ion Channels

    Sung Chul Lee; Chae Woo Lim; Wenzhi Lan; Kai He; Sheng Luan

    2013-01-01

    Plant hormone abscisic acid (ABA) serves as an integrator of environmental stresses such as drought to trigger stomatal closure by regulating specific ion channels in guard cells.We previously reported that SLACl,an outward anion channel required for stomatal closure,was regulated via reversible protein phosphorylation events involving ABA signaling components,including protein phosphatase 2C members and a SnRK2-type kinase (OST1).In this study,we reconstituted the ABA signaling pathway as a protein-protein interaction relay from the PYL/RCAR-type receptors,to the PP2C-SnRK2 phosphatase-kinase pairs,to the ion channel SLACl.The ABA receptors interacted with and inhibited PP2C phosphatase activity against the SnRK2-type kinase,releasing active SnRK2 kinase to phosphorylate,and activate the SLACl channel,leading to reduced guard cell turgor and stomatal closure.Both yeast two-hybrid and bimolecular fluorescence complementation assays were used to verify the interactions among the components in the pathway.These biochemical assays demonstrated activity modifications of phosphatases and kinases by their interaction partners.The SLACl channel activity was used as an endpoint readout for the strength of the signaling pathway,depending on the presence of different combinations of signaling components.Further study using transgenic plants overexpressing one of the ABA receptors demonstrated that changing the relative level of interacting partners would change ABA sensitivity.

  11. Activation of protein tyrosine phosphatase non-receptor type 2 by spermidine exerts anti-inflammatory effects in human THP-1 monocytes and in a mouse model of acute colitis.

    Belén Morón

    Full Text Available BACKGROUND: Spermidine is a dietary polyamine that is able to activate protein tyrosine phosphatase non-receptor type 2 (PTPN2. As PTPN2 is known to be a negative regulator of interferon-gamma (IFN-γ-induced responses, and IFN-γ stimulation of immune cells is a critical process in the immunopathology of inflammatory bowel disease (IBD, we wished to explore the potential of spermidine for reducing pro-inflammatory effects in vitro and in vivo. METHODS: Human THP-1 monocytes were treated with IFN-γ and/or spermidine. Protein expression and phosphorylation were analyzed by Western blot, cytokine expression by quantitative-PCR, and cytokine secretion by ELISA. Colitis was induced in mice by dextran sodium sulfate (DSS administration. Disease severity was assessed by recording body weight, colonoscopy and histology. RESULTS: Spermidine increased expression and activity of PTPN2 in THP-1 monocytes and reduced IFN-γ-induced phosphorylation of signal transducer and activator of transcription (STAT 1 and 3, as well as p38 mitogen-activated protein kinase (MAPK in a PTPN2 dependent manner. Subsequently, IFN-γ-induced expression/secretion of intracellular cell adhesion molecule (ICAM-1 mRNA, monocyte chemoattractant protein (MCP-1, and interleukin (IL-6 was reduced in spermidine-treated cells. The latter effects were absent in PTPN2-knockdown cells. In mice with DSS-induced colitis, spermidine treatment resulted in ameliorated weight loss and decreased mucosal damage indicating reduced disease severity. CONCLUSIONS: Activation of PTPN2 by spermidine ameliorates IFN-γ-induced inflammatory responses in THP-1 cells. Furthermore, spermidine treatment significantly reduces disease severity in mice with DSS-induced colitis; hence, spermidine supplementation and subsequent PTPN2 activation may be helpful in the treatment of chronic intestinal inflammation such as IBD.

  12. Regulation of myotubularin-related (MTMR)2 phosphatidylinositol phosphatase by MTMR5, a catalytically inactive phosphatase

    Kim, Soo-A; Vacratsis, Panayiotis O.; Firestein, Ron; Cleary, Michael L.; Dixon, Jack E.

    2003-01-01

    The myotubularin (MTM) family constitutes one of the most highly conserved protein-tyrosine phosphatase subfamilies in eukaryotes. MTM1, the archetypal member of this family, is mutated in X-linked myotubular myopathy, whereas mutations in the MTM-related (MTMR)2 gene cause the type 4B1 Charcot–Marie-Tooth disease, a severe hereditary motor and sensory neuropathy. In this study, we identified a protein that specifically interacts with MTMR2 but not MTM1. The interacting protein was shown by m...

  13. High expression of ubiquitin-conjugating enzyme 2C (UBE2C) correlates with nasopharyngeal carcinoma progression

    Overexpression of ubiquitin-conjugating enzyme 2C (UBE2C) has been detected in many types of human cancers, and is correlated with tumor malignancy. However, the role of UBE2C in human nasopharyngeal carcinoma (NPC) is unclear. In this study, we investigated the role of aberrant UBE2C expression in the progression of human NPC. Immunohistochemical analysis was performed to detect UBE2C protein in clinical samples of NPC and benign nasopharyngeal tissues, and the association of UBE2C expression with patient clinicopathological characteristics was analyzed. UBEC2 expression profiles were evaluated in cell lines representing varying differentiated stages of NPC and immortalized nasopharyngeal epithelia NP-69 cells using quantitative RT-PCR, western blotting and fluorescent staining. Furthermore, UBE2C was knocked down using RNA interference in these cell lines and proliferation and cell cycle distribution was investigated. Immunohistochemical analysis revealed that UBE2C protein expression levels were higher in NPC tissues than in benign nasopharyngeal tissues (P<0.001). Moreover, high UBE2C protein expression was positively correlated with tumor size (P=0.017), lymph node metastasis (P=0.016) and distant metastasis (P=0.015) in NPC patients. In vitro experiments demonstrated that UBE2C expression levels were inversely correlated with the degree of differentiation of NPC cell lines, whereas UBE2C displayed low level of expression in NP-69 cells. Knockdown of UBE2C led to significant arrest at the S and G2/M phases of the cell cycle, and decreased cell proliferation was observed in poorly-differentiated CNE2Z NPC cells and undifferentiated C666-1 cells, but not in well-differentiated CNE1 and immortalized NP-69 cells. Our findings suggest that high expression of UBE2C in human NPC is closely related to tumor malignancy, and may be a potential marker for NPC progression

  14. Activation of p38 mitogen-activated protein kinase contribute to BMP4-induced alkaline phosphatase expression in MC3T3-E1 preosteoblast

    YUAN Ye; Wu Zhi-jun; YAO Hui-yu; YU Xiao-dan; GUO Zi-kuan; CHEN Xiao-san; TANG Pei-xian; MAO Ning

    2006-01-01

    @@ Bone morphogenetic proteins (BMPs) induce ectopic bone formation and promote osteoblast differentiation.1 It has been documented that Smad transcriptional factors function as primary mediators of BMPs activity. Receptor-regulated Smad (Smad1, 5, 8) could be phosphorylated by activated BMPR-I and form complex with Smad4. The Smad complex translocates to the nucleus and regulate target gene transcription.2

  15. Association between receptor protein-tyrosine phosphatase RPTPalpha and the Grb2 adaptor. Dual Src homology (SH) 2/SH3 domain requirement and functional consequences

    Su, J; Yang, L T; Sap, J

    1996-01-01

    binding site in RPTPalpha was studied further by expression of wild type or mutant RPTPalpha proteins in PC12 cells. In these cells, wild type RPTPalpha interferes with acidic fibroblast growth factor-induced neurite outgrowth; this effect requires both the catalytic activity and the Grb2 binding Tyr798...

  16. New Functions of the Inositol Polyphosphate 5-Phosphatases in Cancer.

    Erneux, Christophe; Ghosh, Somadri; Ramos, Ana Raquel; Edimo, William's Elong

    2016-01-01

    Inositol polyphosphate 5-phosphatases act on inositol phosphates and phosphoinositides as substrates. They are 10 different isoenzymes and several splice variants in the human genome that are involved in a series of human pathologies such as the Lowe syndrome, the Joubert and MORM syndromes, breast cancer, glioblastoma, gastric cancer and several other type of cancers. Inositol 5-phosphatases can be amplified in human cancer cells, whereas the 3- and 4- phosphatase tumor suppressor PTEN and INPP4B, repectively are often repressed or deleted. The inositol 5-phosphatases are critically involved in a complex network of higly regulated phosphoinositides, affecting the lipid content of PI(3, 4, 5)P3, PI(4, 5)P2 and PI(3, 4)P2. This has an impact on the normal behavior of many intracellular target proteins e.g. protein kinase B (PKB/Akt) or actin binding proteins and final biological responses. The production of PI(3, 4P)2 by dephosphorylation of the substrate PI(3, 4, 5)P3 is particularly important as it produces a new signal messenger in the control of cell migration, invasion and endocytosis. New inhibitors/activators of inositol 5- phosphatases have recently been identified for the possible control of their activity in several human pathologies such as inflamation and cancer. PMID:26916021

  17. The catalytic properties of alkaline phosphatases under various conditions

    Atyaksheva, L. F.; Chukhrai, E. S.; Poltorak, O. M.

    2008-11-01

    A comparative study was performed to examine the catalytic properties of alkaline phosphatases from bacteria Escherichia coli and bovine and chicken intestines. The activity of enzyme dimers and tetramers was determined. The activity of the dimer was three or four times higher than that of the tetramer. The maximum activity and affinity for 4-nitrophenylphosphate was observed for the bacterial alkaline phosphatase ( K M = 1.7 × 10-5 M, V max = 1800 μmol/(min mg of protein) for dimers and V max = 420 μmol/(min mg of protein) for tetramers). The Michaelis constants were equal for two animal phosphatases in various buffer media (pH 8.5) ((3.5 ± 0.2) × 10-4 M). Five buffer systems were investigated: tris, carbonate, hepes, borate, and glycine buffers, and the lowest catalytic activity of alkaline phosphatases at equal pH was observed in the borate buffer (for enzyme from bovine intestine, V max = 80 μmol/(min mg of protein)). Cu2+ cations formed a complex with tris-(oxymethyl)-aminomethane ( tris-HCl buffer) and inhibited the intestine alkaline phosphatases by a noncompetitive mechanism.

  18. A KH-Domain RNA-Binding Protein Interacts with FIERY2/CTD Phosphatase-Like 1 and Splicing Factors and Is Important for Pre-mRNA Splicing in Arabidopsis

    Chen, Tao

    2013-10-17

    Eukaryotic genomes encode hundreds of RNA-binding proteins, yet the functions of most of these proteins are unknown. In a genetic study of stress signal transduction in Arabidopsis, we identified a K homology (KH)-domain RNA-binding protein, HOS5 (High Osmotic Stress Gene Expression 5), as required for stress gene regulation and stress tolerance. HOS5 was found to interact with FIERY2/RNA polymerase II (RNAP II) carboxyl terminal domain (CTD) phosphatase-like 1 (FRY2/CPL1) both in vitro and in vivo. This interaction is mediated by the first double-stranded RNA-binding domain of FRY2/CPL1 and the KH domains of HOS5. Interestingly, both HOS5 and FRY2/CPL1 also interact with two novel serine-arginine (SR)-rich splicing factors, RS40 and RS41, in nuclear speckles. Importantly, FRY2/CPL1 is required for the recruitment of HOS5. In fry2 mutants, HOS5 failed to be localized in nuclear speckles but was found mainly in the nucleoplasm. hos5 mutants were impaired in mRNA export and accumulated a significant amount of mRNA in the nuclei, particularly under salt stress conditions. Arabidopsis mutants of all these genes exhibit similar stress-sensitive phenotypes. RNA-seq analyses of these mutants detected significant intron retention in many stress-related genes under salt stress but not under normal conditions. Our study not only identified several novel regulators of pre-mRNA processing as important for plant stress response but also suggested that, in addition to RNAP II CTD that is a well-recognized platform for the recruitment of mRNA processing factors, FRY2/CPL1 may also recruit specific factors to regulate the co-transcriptional processing of certain transcripts to deal with environmental challenges. © 2013 Chen et al.

  19. Glucose-6-phosphatase deficiency

    Labrune Philippe

    2011-05-01

    Full Text Available Abstract Glucose-6-phosphatase deficiency (G6P deficiency, or glycogen storage disease type I (GSDI, is a group of inherited metabolic diseases, including types Ia and Ib, characterized by poor tolerance to fasting, growth retardation and hepatomegaly resulting from accumulation of glycogen and fat in the liver. Prevalence is unknown and annual incidence is around 1/100,000 births. GSDIa is the more frequent type, representing about 80% of GSDI patients. The disease commonly manifests, between the ages of 3 to 4 months by symptoms of hypoglycemia (tremors, seizures, cyanosis, apnea. Patients have poor tolerance to fasting, marked hepatomegaly, growth retardation (small stature and delayed puberty, generally improved by an appropriate diet, osteopenia and sometimes osteoporosis, full-cheeked round face, enlarged kydneys and platelet dysfunctions leading to frequent epistaxis. In addition, in GSDIb, neutropenia and neutrophil dysfunction are responsible for tendency towards infections, relapsing aphtous gingivostomatitis, and inflammatory bowel disease. Late complications are hepatic (adenomas with rare but possible transformation into hepatocarcinoma and renal (glomerular hyperfiltration leading to proteinuria and sometimes to renal insufficiency. GSDI is caused by a dysfunction in the G6P system, a key step in the regulation of glycemia. The deficit concerns the catalytic subunit G6P-alpha (type Ia which is restricted to expression in the liver, kidney and intestine, or the ubiquitously expressed G6P transporter (type Ib. Mutations in the genes G6PC (17q21 and SLC37A4 (11q23 respectively cause GSDIa and Ib. Many mutations have been identified in both genes,. Transmission is autosomal recessive. Diagnosis is based on clinical presentation, on abnormal basal values and absence of hyperglycemic response to glucagon. It can be confirmed by demonstrating a deficient activity of a G6P system component in a liver biopsy. To date, the diagnosis is most

  20. Substrate Specificity of Lymphoid-specific Tyrosine Phosphatase (Lyp) and Identification of Src Kinase-associated Protein of 55 kDa Homolog (SKAP-HOM) as a Lyp Substrate

    Yu, Xiao; Chen, Ming; Zhang, Sheng; Yu, Zhi-Hong; Sun, Jin-Peng; Wang, Lina; Liu, Sijiu; Imasaki, Tsuyoshi; Takagi, Yuichiro; Zhang, Zhong-Yin (Indiana-Med)

    2012-02-08

    A missense single-nucleotide polymorphism in the gene encoding the lymphoid-specific tyrosine phosphatase (Lyp) has been identified as a causal factor in a wide spectrum of autoimmune diseases. Interestingly, the autoimmune-predisposing variant of Lyp appears to represent a gain-of-function mutation, implicating Lyp as an attractive target for the development of effective strategies for the treatment of many autoimmune disorders. Unfortunately, the precise biological functions of Lyp in signaling cascades and cellular physiology are poorly understood. Identification and characterization of Lyp substrates will help define the chain of molecular events coupling Lyp dysfunction to diseases. In the current study, we identified consensus sequence motifs for Lyp substrate recognition using an 'inverse alanine scanning' combinatorial library approach. The intrinsic sequence specificity data led to the discovery and characterization of SKAP-HOM, a cytosolic adaptor protein required for proper activation of the immune system, as a bona fide Lyp substrate. To determine the molecular basis for Lyp substrate recognition, we solved crystal structures of Lyp in complex with the consensus peptide as well as the phosphopeptide derived from SKAP-HOM. Together with the biochemical data, the structures define the molecular determinants for Lyp substrate specificity and provide a solid foundation upon which novel therapeutics targeting Lyp can be developed for multiple autoimmune diseases.

  1. Novel 2,7-Substituted (S)-1,2,3,4-Tetrahydroisoquinoline-3-carboxylic Acids: Peroxisome Proliferator-Activated Receptor γ Partial Agonists with Protein-Tyrosine Phosphatase 1B Inhibition.

    Otake, Kazuya; Azukizawa, Satoru; Takeda, Shigemitsu; Fukui, Masaki; Kawahara, Arisa; Kitao, Tatsuya; Shirahase, Hiroaki

    2015-01-01

    A novel series of 2,7-substituted 1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid derivatives were synthesized and biologically evaluated. (S)-2-(2-Furylacryloyl)-7-[2-(2-methylindane-2-yl)-5-methyloxazol-4-yl]methoxy-1,2,3,4-tetrahydroisoquinoline-3-carboxylic acid tert-butylamine salt (13jE) was identified as a potent human peroxisome proliferator-activated receptor γ (PPARγ)-selective agonist (EC50=85 nM) and human protein-tyrosine phosphatase 1B (PTP-1B) inhibitor (IC50=1.0 µM). Compound 13jE partially activated PPARγ, but not PPARα or PPARδ, and antagonized farglitazar, a full PPARγ agonist. Cmax after the oral administration of 13jE at 10 mg/kg was 28.6 µg/mL (53 µM) in male Sprague-Dawley (SD) rats. Repeated administration of 13jE and rosiglitazone for 14 d at 10 mg/kg/d decreased plasma glucose and triglyceride levels significantly in male KK-A(y) mice. Rosiglitazone, but not 13jE, significantly increased the plasma volume and liver weight. In conclusion, 13jE showed stronger hypoglycemic and hypolipidemic effects and weaker hemodilution and hepatotoxic effects than rosiglitazone, suggesting that its safer efficacy may be due to its partial PPARγ agonism and PTP-1B inhibition. PMID:26633022

  2. Tartrate-resistant acid phosphatase (TRAP) co-localizes with receptor activator of NF-KB ligand (RANKL) and osteoprotegerin (OPG) in lysosomal-associated membrane protein 1 (LAMP1)-positive vesicles in rat osteoblasts and osteocytes.

    Solberg, L B; Stang, E; Brorson, S-H; Andersson, G; Reinholt, F P

    2015-02-01

    Tartrate-resistant acid phosphatase (TRAP) is well known as an osteoclast marker; however, a recent study from our group demonstrated enhanced number of TRAP + osteocytes as well as enhanced levels of TRAP located to intracellular vesicles in osteoblasts and osteocytes in experimental osteoporosis in rats. Such vesicles were especially abundant in osteoblasts and osteocytes in cancellous bone as well as close to bone surface and intracortical remodeling sites. To further investigate TRAP in osteoblasts and osteocytes, long bones from young, growing rats were examined. Immunofluorescence confocal microscopy displayed co-localization of TRAP with receptor activator of NF-KB ligand (RANKL) and osteoprotegerin (OPG) in hypertrophic chondrocytes and diaphyseal osteocytes with Pearson's correlation coefficient ≥0.8. Transmission electron microscopy showed co-localization of TRAP and RANKL in lysosomal-associated membrane protein 1 (LAMP1) + vesicles in osteoblasts and osteocytes supporting the results obtained by confocal microscopy. Recent in vitro data have demonstrated OPG as a traffic regulator for RANKL to LAMP1 + secretory lysosomes in osteoblasts and osteocytes, which seem to serve as temporary storage compartments for RANKL. Our in situ observations indicate that TRAP is located to RANKL-/OPG-positive secretory lysosomes in osteoblasts and osteocytes, which may have implications for osteocyte regulation of osteoclastogenesis. PMID:25201349

  3. Paired Box Gene 8-Peroxisome Proliferator-Activated Receptor-γ Fusion Protein and Loss of Phosphatase and Tensin Homolog Synergistically Cause Thyroid Hyperplasia in Transgenic Mice

    Diallo-Krou, Ericka; Yu, Jingcheng; Colby, Lesley A.; Inoki, Ken; Wilkinson, John E.; Thomas, Dafydd G.; Giordano, Thomas J.; Koenig, Ronald J.

    2009-01-01

    Approximately 35% of follicular thyroid carcinomas and a small fraction of follicular adenomas are associated with a t(2;3)(q13;p25) chromosomal translocation that fuses paired box gene 8 (PAX8) with the peroxisome proliferator-activated receptor-γ gene (PPARG), resulting in expression of a PAX8-PPARγ fusion protein, PPFP. The mechanism by which PPFP contributes to follicular thyroid neoplasia is poorly understood. Therefore, we have created mice with thyroid-specific expression of PPFP. At 1...

  4. Activated Integrin-Linked Kinase Negatively Regulates Muscle Cell Enhancement Factor 2C in C2C12 Cells

    Zhenguo Dong

    2015-01-01

    Full Text Available Our previous study reported that muscle cell enhancement factor 2C (MEF2C was fully activated after inhibition of the phosphorylation activity of integrin-linked kinase (ILK in the skeletal muscle cells of goats. It enhanced the binding of promoter or enhancer of transcription factor related to proliferation of muscle cells and then regulated the expression of these genes. In the present investigation, we explored whether ILK activation depended on PI3K to regulate the phosphorylation and transcriptional activity of MEF2C during C2C12 cell proliferation. We inhibited PI3K activity in C2C12 with LY294002 and then found that ILK phosphorylation levels and MEF2C phosphorylation were decreased and that MCK mRNA expression was suppressed significantly. After inhibiting ILK phosphorylation activity with Cpd22 and ILK-shRNA, we found MEF2C phosphorylation activity and MCK mRNA expression were increased extremely significantly. In the presence of Cpd22, PI3K activity inhibition increased MEF2C phosphorylation and MCK mRNA expression indistinctively. We conclude that ILK negatively and independently of PI3K regulated MEF2C phosphorylation activity and MCK mRNA expression in C2C12 cells. The results provide new ideas for the study of classical signaling pathway of PI3K-ILK-related proteins and transcription factors.

  5. Protein tyrosine phosphatase µ (PTP µ or PTPRM, a negative regulator of proliferation and invasion of breast cancer cells, is associated with disease prognosis.

    Ping-Hui Sun

    Full Text Available BACKGROUND: PTPRM has been shown to exhibit homophilic binding and confer cell-cell adhesion in cells including epithelial and cancer cells. The present study investigated the expression of PTPRM in breast cancer and the biological impact of PTPRM on breast cancer cells. DESIGN: Expression of PTPRM protein and gene transcript was examined in a cohort of breast cancer patients. Knockdown of PTPRM in breast cancer cells was performed using a specific anti-PTPRM transgene. The impact of PTPRM knockdown on breast cancer was evaluated using in vitro cell models. RESULTS: A significant decrease of PTPRM transcripts was seen in poorly differentiated and moderately differentiated tumours compared with well differentiated tumours. Patients with lower expression of PTPRM had shorter survival compared with those which had a higher level of PTPRM expression. Knockdown of PTPRM increased proliferation, adhesion, invasion and migration of breast cancer cells. Furthermore, knockdown of PTPRM in MDA-MB-231 cells resulted in increased cell migration and invasion via regulation of the tyrosine phosphorylation of ERK and JNK. CONCLUSIONS: Decreased expression of PTPRM in breast cancer is correlated with poor prognosis and inversely correlated with disease free survival. PTPRM coordinated cell migration and invasion through the regulation of tyrosine phosphorylation of ERK and JNK.

  6. Isoliquiritigenin impairs insulin signaling and adipocyte differentiation through the inhibition of protein-tyrosine phosphatase 1B oxidation in 3T3-L1 preadipocytes.

    Park, Sun-Ji; Choe, Young-Geun; Kim, Jung-Hak; Chang, Kyu-Tae; Lee, Hyun-Shik; Lee, Dong-Seok

    2016-07-01

    Isoliquritigenin (ISL) is an abundant dietary flavonoid with a chalcone structure, which is an important constituent in Glycyrrhizae Radix (GR). ISL exhibits anti-oxidant activity, and this activity has been shown to play a beneficial role in various health conditions. However, it is unclear whether the anti-oxidant activity of ISL affects insulin signaling pathway and lipid accumulation of adipocytes. We sought to investigate the effects and molecular mechanisms of ISL on insulin-stimulated adipogenesis in 3T3-L1 cells. We investigated whether ISL attenuates insulin-induced Reactive Oxygen Species (ROS) generation, and whether ISL inhibits the lipid accumulation and the expression of adipogenic-genes during the differentiation of 3T3-L1 cells. ISL blocked the ROS generation, suppressed the lipid accumulation and the expression of adipocyte-specific proteins, which are increased in response to insulin stimulation during adipocyte differentiation of 3T3-L1 cells. We also investigated whether the anti-oxidant capacity of ISL is involved in regulating the molecular events of insulin-signaling cascade in 3T3-L1 adipocytes. ISL restores PTP1B activity by inhibiting PTP1B oxidation and IR/PI3K/AKT phosphorylation during the early stages of insulin-induced adipogenesis. Our findings show that the anti-oxidant capacity of ISL attenuated insulin IR/PI3K/AKT signaling through inhibition of PTP1B oxidation, and ultimately attenuated insulin-induced adipocyte differentiation of 3T3-L1 cells. PMID:27117918

  7. Differential pattern of glycogen accumulation after protein phosphatase 1 glycogen-targeting subunit PPP1R6 overexpression, compared to PPP1R3C and PPP1R3A, in skeletal muscle cells

    Montori-Grau Marta

    2011-11-01

    Full Text Available Abstract Background PPP1R6 is a protein phosphatase 1 glycogen-targeting subunit (PP1-GTS abundant in skeletal muscle with an undefined metabolic control role. Here PPP1R6 effects on myotube glycogen metabolism, particle size and subcellular distribution are examined and compared with PPP1R3C/PTG and PPP1R3A/GM. Results PPP1R6 overexpression activates glycogen synthase (GS, reduces its phosphorylation at Ser-641/0 and increases the extracted and cytochemically-stained glycogen content, less than PTG but more than GM. PPP1R6 does not change glycogen phosphorylase activity. All tested PP1-GTS-cells have more glycogen particles than controls as found by electron microscopy of myotube sections. Glycogen particle size is distributed for all cell-types in a continuous range, but PPP1R6 forms smaller particles (mean diameter 14.4 nm than PTG (36.9 nm and GM (28.3 nm or those in control cells (29.2 nm. Both PPP1R6- and GM-derived glycogen particles are in cytosol associated with cellular structures; PTG-derived glycogen is found in membrane- and organelle-devoid cytosolic glycogen-rich areas; and glycogen particles are dispersed in the cytosol in control cells. A tagged PPP1R6 protein at the C-terminus with EGFP shows a diffuse cytosol pattern in glucose-replete and -depleted cells and a punctuate pattern surrounding the nucleus in glucose-depleted cells, which colocates with RFP tagged with the Golgi targeting domain of β-1,4-galactosyltransferase, according to a computational prediction for PPP1R6 Golgi location. Conclusions PPP1R6 exerts a powerful glycogenic effect in cultured muscle cells, more than GM and less than PTG. PPP1R6 protein translocates from a Golgi to cytosolic location in response to glucose. The molecular size and subcellular location of myotube glycogen particles is determined by the PPP1R6, PTG and GM scaffolding.

  8. Early glycogen synthase kinase-3β and protein phosphatase 2A independent tau dephosphorylation during global brain ischaemia and reperfusion following cardiac arrest and the role of the adenosine monophosphate kinase pathway.

    Majd, Shohreh; Power, John H T; Koblar, Simon A; Grantham, Hugh J M

    2016-08-01

    Abnormal tau phosphorylation (p-tau) has been shown after hypoxic damage to the brain associated with traumatic brain injury and stroke. As the level of p-tau is controlled by Glycogen Synthase Kinase (GSK)-3β, Protein Phosphatase 2A (PP2A) and Adenosine Monophosphate Kinase (AMPK), different activity levels of these enzymes could be involved in tau phosphorylation following ischaemia. This study assessed the effects of global brain ischaemia/reperfusion on the immediate status of p-tau in a rat model of cardiac arrest (CA) followed by cardiopulmonary resuscitation (CPR). We reported an early dephosphorylation of tau at its AMPK sensitive residues, Ser(396) and Ser(262) after 2 min of ischaemia, which did not recover during the first two hours of reperfusion, while the tau phosphorylation at GSK-3β sensitive but AMPK insensitive residues, Ser(202) /Thr(205) (AT8), as well as the total amount of tau remained unchanged. Our data showed no alteration in the activities of GSK-3β and PP2A during similar episodes of ischaemia of up to 8 min and reperfusion of up to 2 h, and 4 weeks recovery. Dephosphorylation of AMPK followed the same pattern as tau dephosphorylation during ischaemia/reperfusion. Catalase, another AMPK downstream substrate also showed a similar pattern of decline to p-AMPK, in ischaemic/reperfusion groups. This suggests the involvement of AMPK in changing the p-tau levels, indicating that tau dephosphorylation following ischaemia is not dependent on GSK-3β or PP2A activity, but is associated with AMPK dephosphorylation. We propose that a reduction in AMPK activity is a possible early mechanism responsible for tau dephosphorylation. PMID:27177932

  9. Development of a gene therapy strategy to target hepatocellular carcinoma based inhibition of protein phosphatase 2A using the α-fetoprotein promoter enhancer and pgk promoter: an in vitro and in vivo study

    Li Wei

    2012-11-01

    Full Text Available Abstract Background Hepatocellular carcinoma (HCC is one of the leading causes of cancer-related deaths worldwide. Current therapies are insufficient, making HCC an intractable disease. Our previous studies confirmed that inhibition of protein phosphatase 2A (PP2A may provide a promising therapeutic strategy for cancer. Unfortunately, constitutive expression of PP2A in normal tissues limits the application of PP2A inhibition. Thus, a HCC-specific gene delivery system should be developed. The α-fetoprotein (AFP promoter is commonly used in HCC-specific gene therapy strategies; however, the utility of this approach is limited due to the weak activity of the AFP promoter. It has been shown that linking the AFP enhancer with the promoter of the non-tissue-specific, human housekeeping phosphoglycerate kinase (pgk gene can generate a strong and HCC-selective promoter. Methods We constructed a HCC-specific gene therapy system to target PP2A using the AFP enhancer/pgk promoter, and evaluated the efficiency and specificity of this system both in vitro and in vivo. Results AFP enhancer/pgk promoter-driven expression of the dominant negative form of the PP2A catalytic subunit α (DN-PP2Acα exerted cytotoxic effects against an AFP-positive human hepatoma cell lines (HepG2 and Hep3B, but did not affect AFP-negative human hepatoma cells (SK-HEP-1 or normal human liver cells (L-02. Moreover, AFP enhancer/pgk promoter driven expression of DN-PP2Acα inhibited the growth of AFP-positive HepG2 tumors in nude mice bearing solid tumor xenografts, but did not affect AFP-negative SK-HEP-1 tumors. Conclusions The novel approach of AFP enhancer/pgk promoter-driven expression of DN-PP2Acα may provide a useful cancer gene therapy strategy to selectively target HCC.

  10. Development of a gene therapy strategy to target hepatocellular carcinoma based inhibition of protein phosphatase 2A using the α-fetoprotein promoter enhancer and pgk promoter: an in vitro and in vivo study

    Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related deaths worldwide. Current therapies are insufficient, making HCC an intractable disease. Our previous studies confirmed that inhibition of protein phosphatase 2A (PP2A) may provide a promising therapeutic strategy for cancer. Unfortunately, constitutive expression of PP2A in normal tissues limits the application of PP2A inhibition. Thus, a HCC-specific gene delivery system should be developed. The α-fetoprotein (AFP) promoter is commonly used in HCC-specific gene therapy strategies; however, the utility of this approach is limited due to the weak activity of the AFP promoter. It has been shown that linking the AFP enhancer with the promoter of the non-tissue-specific, human housekeeping phosphoglycerate kinase (pgk) gene can generate a strong and HCC-selective promoter. We constructed a HCC-specific gene therapy system to target PP2A using the AFP enhancer/pgk promoter, and evaluated the efficiency and specificity of this system both in vitro and in vivo. AFP enhancer/pgk promoter-driven expression of the dominant negative form of the PP2A catalytic subunit α (DN-PP2Acα) exerted cytotoxic effects against an AFP-positive human hepatoma cell lines (HepG2 and Hep3B), but did not affect AFP-negative human hepatoma cells (SK-HEP-1) or normal human liver cells (L-02). Moreover, AFP enhancer/pgk promoter driven expression of DN-PP2Acα inhibited the growth of AFP-positive HepG2 tumors in nude mice bearing solid tumor xenografts, but did not affect AFP-negative SK-HEP-1 tumors. The novel approach of AFP enhancer/pgk promoter-driven expression of DN-PP2Acα may provide a useful cancer gene therapy strategy to selectively target HCC

  11. Maternal antibiotic-induced early changes in microbial colonization selectively modulate colonic permeability and inducible heat shock proteins, and digesta concentrations of alkaline phosphatase and TLR-stimulants in swine offspring.

    Marie-Edith Arnal

    Full Text Available Elevated intake of high energy diets is a risk factor for the development of metabolic diseases and obesity. High fat diets cause alterations in colonic microbiota composition and increase gut permeability to bacterial lipopolysaccharide, and subsequent low-grade chronic inflammation in mice. Chronic inflammatory bowel diseases are increasing worldwide and may involve alterations in microbiota-host dialog. Metabolic disorders appearing in later life are also suspected to reflect changes in early programming. However, how the latter affects the colon remains poorly studied. Here, we hypothesized that various components of colonic physiology, including permeability, ion exchange and protective inducible heat shock proteins (HSP are influenced in the short- and long-terms by early disturbances in microbial colonization. The hypothesis was tested in a swine model. Offspring were born to control mothers (n = 12 or mothers treated with the antibiotic (ATB amoxicillin around parturition (n = 11. Offspring were slaughtered between 14 and 42 days of age to study short-term effects. For long-term effects, young adult offspring from the same litters consumed a normal or a palm oil-enriched diet for 4 weeks between 140 and 169 days of age. ATB treatment transiently modified maternal fecal microbiota although the minor differences observed for offspring colonic microbiota were nonsignificant. In the short-term, consistently higher HSP27 and HSP70 levels and transiently increased horseradish peroxidase permeability in ATB offspring colon were observed. Importantly, long-term consequences included reduced colonic horseradish peroxidase permeability, and increased colonic digesta alkaline phosphatase (AP and TLR2- and TLR4-stimulant concentrations in rectal digesta in adult ATB offspring. Inducible HSP27 and HSP70 did not change. Interactions between early ATB treatment and later diet were noted for paracellular permeability and concentrations of colonic

  12. Characterization of Human Bone Alkaline Phosphatase in Pichia Pastoris

    Malone, Christine C.; Ciszak, Eva; Karr, Laurel J.

    1999-01-01

    A soluble form of human bone alkaline phosphatase has been expressed in a recombinant strain of the methylotrophic yeast Pichia pastoris. We constructed a plasmid containing cDNA encoding for human bone alkaline phosphatase, with the hydrophobic carboxyl terminal portion deleted. Alkaline phosphatase was secreted into the medium to a level of 32mg/L when cultured in shake flasks, and enzyme activity was 12U/mg, as measured by a spectrophotometric assay. By conversion to a fermentation system, a yield of 880mg/L has been achieved with an enzyme activity of 968U/mg. By gel electrophoresis analysis, it appears that greater than 50% of the total protein in the fermentation media is alkaline phosphatase. Although purification procedures are not yet completely optimized, they are expected to include filtration, ion exchange and affinity chromatography. Our presentation will focus on the purification and crystallization results up to the time of the conference. Structural data should provide additional information on the role of alkaline phosphatase in normal bone mineralization and in certain bone mineralization anomalies.

  13. Growth hormone (GH) treatment increases serum insulin-like growth factor binding protein-3, bone isoenzyme alkaline phosphatase and forearm bone mineral content in young adults with GH deficiency of childhood onset

    Juul, A; Pedersen, S A; Sørensen, S; Winkler, K; Jørgensen, J O; Christiansen, J S; Skakkebaek, N E

    1994-01-01

    the effect of GH treatment on a marker of bone formation (bone alkaline phosphatase), hepatic excretory function and distal forearm bone mineral content in GH-deficient adults. Growth hormone was administered subcutaneously in 21 adults (13 males and 8 females) with GH deficiency of childhood onset....../l after 4 months of GH treatment (p <0.0001). In addition, the molar ratio between IGF-I and IGFBP-3 increased significantlyfrom 0.22 to 0.33 after GH treatment (p <0.0001). Bone alkaline phosphatase increased significantly from 38.6 to 92.9 U/l during GH therapy in male patients (p <0.0001), whereas...... liver-derived alkaline phosphatase was unaltered by GH. In the females, the increase in bone alkaline phosphatase did not reach statistical significance (19.1 vs 40.0 U/l, p = 0.06). The GH-induced increase in bone alkaline phosphatase correlated significantly with the increase in serum IGFBP-3 (r = 0...

  14. Selective dephosphorylation of histone H1 by nuclear phosphatases

    The aim of this study was to characterize the sites of H1 phosphorylated by the cAMP-dependent protein kinase (kinase A) and the Ca2+ phospholipid-dependent protein kinase (kinase C) and to study their dephosphorylation by nuclear protein phosphatases. H1 was phosphorylated on a ser residue to approx. 1 mole [32P]/mole H1 with either kinase A or C. The sites of phosphorylation were differentiated by digestion of the H1 by thrombin or N-bromosuccinimide. Phosphopeptide maps on reversed phase HPLC and gel filtration HPLC clearly showed that the kinase C phosphorylated a different site than the well characterized kinase A site. H1, phosphorylated by kinase C or kinase A, was used as a substrate for the nuclear phosphatases. The nuclear phosphatases were purified from salt extracted rat liver chromatin and separated into 2 forms based on heat-stable inhibitor sensitivity and polycation stimulation. Polycation-stimulated phosphatase rapidly dephosphorylated the kinase C site and slowly dephosphorylated the kinase A site. The inhibitor-sensitive enzyme showed little activity toward either site under standard assay conditions

  15. Selective dephosphorylation of histone H1 by nuclear phosphatases

    Jakes, S.; Schlender, K.K.

    1987-05-01

    The aim of this study was to characterize the sites of H1 phosphorylated by the cAMP-dependent protein kinase (kinase A) and the CaS phospholipid-dependent protein kinase (kinase C) and to study their dephosphorylation by nuclear protein phosphatases. H1 was phosphorylated on a ser residue to approx. 1 mole (TSP)/mole H1 with either kinase A or C. The sites of phosphorylation were differentiated by digestion of the H1 by thrombin or N-bromosuccinimide. Phosphopeptide maps on reversed phase HPLC and gel filtration HPLC clearly showed that the kinase C phosphorylated a different site than the well characterized kinase A site. H1, phosphorylated by kinase C or kinase A, was used as a substrate for the nuclear phosphatases. The nuclear phosphatases were purified from salt extracted rat liver chromatin and separated into 2 forms based on heat-stable inhibitor sensitivity and polycation stimulation. Polycation-stimulated phosphatase rapidly dephosphorylated the kinase C site and slowly dephosphorylated the kinase A site. The inhibitor-sensitive enzyme showed little activity toward either site under standard assay conditions.

  16. PP2C-like Promoter and Its Deletion Variants Are Induced by ABA but Not by MeJA and SA in Arabidopsis thaliana

    Bhalothia, Purva; Sangwan, Chetna; Alok, Anshu; Mehrotra, Sandhya; Mehrotra, Rajesh

    2016-01-01

    Gene expression is mediated through interaction between cis regulatory elements and its cognate transcription factors. Cis regulatory elements are defined as non-coding DNA sequences that provide the binding sites for transcription factors and are clustered in the upstream region of genes. ACGT cis regulatory element is one of the important cis regulatory elements found to be involved in diverse biological processes like auxin response, salicylic acid (SA) response, UV light response, ABA response and jasmonic acid (JA) response. We identified through in silico analysis that the upstream region of protein phosphatase 2C (PP2C) gene has a distinct genetic architecture of ACGT elements. In the present study, the activation of the full length promoter and its deletion constructs like 900 base pair, 500 base pair, 400 base pair and NRM (Nathji Rajesh Mehrotra) were examined by stable transformation in Arabidopsis thaliana using β-glucuronidase as the reporter gene. Evaluation of deletion constructs of PP2C-like promoter was carried out in the presence of phytohormones like abscisic acid (ABA), SA and JA. Our result indicated that the full length and 900 base pair promoter-reporter constructs of PP2C-like promoter was induced in response to ABA but not to methyl jasmonate and SA. PMID:27200023

  17. The investigation of Mitogen-Activated Protein kinase Phosphatase-1 as a potential pharmacological target in non-small cell lung carcinomas, assisted by non-invasive molecular imaging

    Invasiveness and metastasis are the most common characteristics of non small cell lung cancer (NSCLC) and causes of tumour-related morbidity and mortality. Mitogen-activated protein kinases (MAPKs) signalling pathways have been shown to play critical roles in tumorigenesis. However, the precise pathological role(s) of mitogen-activated protein kinase phosphatase-1 (MKP-1) in different cancers has been controversial such that the up-regulation of MKP-1 in different cancers does not always correlate to a better prognosis. In this study, we showed that the induction of MKP-1 lead to a significant retardation of proliferation and metastasis in NSCLC cells. We also established that rosiglitazone (a PPARγ agonist) elevated MKP-1 expression level in NSCLC cells and inhibited tumour metastasis. Both wildtype and dominant negative forms of MKP-1 were constitutively expressed in NSCLC cell line H441GL. The migration and invasion abilities of these cells were examined in vitro. MKP-1 modulating agents such as rosiglitazone and triptolide were used to demonstrate MKP-1's role in tumorigenesis. Bioluminescent imaging was utilized to study tumorigenesis of MKP-1 over-expressing H441GL cells and anti-metastatic effect of rosiglitazone. Over-expression of MKP-1 reduced NSCLC cell proliferation rate as well as cell invasive and migratory abilities, evident by the reduced expression levels of MMP-2 and CXCR4. Mice inoculated with MKP-1 over-expressing H441 cells did not develop NSCLC while their control wildtype H441 inoculated littermates developed NSCLC and bone metastasis. Pharmacologically, rosiglitazone, a peroxisome proliferator activated receptor-γ (PPARγ) agonist appeared to induce MKP-1 expression while reduce MMP-2 and CXCR4 expression. H441GL-inoculated mice receiving daily oral rosiglitazone treatment demonstrated a significant inhibition of bone metastasis when compared to mice receiving sham treatment. We found that rosiglitazone treatment impeded the ability

  18. The investigation of Mitogen-Activated Protein kinase Phosphatase-1 as a potential pharmacological target in non-small cell lung carcinomas, assisted by non-invasive molecular imaging

    Chiu Wen-Ta

    2010-03-01

    Full Text Available Abstract Background Invasiveness and metastasis are the most common characteristics of non small cell lung cancer (NSCLC and causes of tumour-related morbidity and mortality. Mitogen-activated protein kinases (MAPKs signalling pathways have been shown to play critical roles in tumorigenesis. However, the precise pathological role(s of mitogen-activated protein kinase phosphatase-1 (MKP-1 in different cancers has been controversial such that the up-regulation of MKP-1 in different cancers does not always correlate to a better prognosis. In this study, we showed that the induction of MKP-1 lead to a significant retardation of proliferation and metastasis in NSCLC cells. We also established that rosiglitazone (a PPARγ agonist elevated MKP-1 expression level in NSCLC cells and inhibited tumour metastasis. Methods Both wildtype and dominant negative forms of MKP-1 were constitutively expressed in NSCLC cell line H441GL. The migration and invasion abilities of these cells were examined in vitro. MKP-1 modulating agents such as rosiglitazone and triptolide were used to demonstrate MKP-1's role in tumorigenesis. Bioluminescent imaging was utilized to study tumorigenesis of MKP-1 over-expressing H441GL cells and anti-metastatic effect of rosiglitazone. Results Over-expression of MKP-1 reduced NSCLC cell proliferation rate as well as cell invasive and migratory abilities, evident by the reduced expression levels of MMP-2 and CXCR4. Mice inoculated with MKP-1 over-expressing H441 cells did not develop NSCLC while their control wildtype H441 inoculated littermates developed NSCLC and bone metastasis. Pharmacologically, rosiglitazone, a peroxisome proliferator activated receptor-γ (PPARγ agonist appeared to induce MKP-1 expression while reduce MMP-2 and CXCR4 expression. H441GL-inoculated mice receiving daily oral rosiglitazone treatment demonstrated a significant inhibition of bone metastasis when compared to mice receiving sham treatment. We found that

  19. Preparation and Characterization of Monclonal Antibody against Protein Tyrosine Phosphatase PRL-3%酪氨酸磷酸酶PRL-3单抗的制备及特性鉴定

    王莉; 杨艳丽; 宋子博; 廖世秀; 黄飞飞

    2009-01-01

    目的 制备并鉴定抗肝再生磷酸酶-3(Phosphatase of Regenerating Liver-3,PRL-3)单克隆抗体,为临床检测和以PRL-3为靶点的肿瘤治疗提供可能.方法 运用杂交瘤融合技术制备PRL-3单克隆抗体,通过Western blot检测和免疫沉淀鉴定其与原核及真核PRL-3蛋白的反应性;重组并诱导表达PRL-3的6个截短体,Western blot分析单抗结合的大致抗原表位.结果 共得到9株单抗,3株与PRL-1、PRL-2和PRL-3均反应,6株(9D8、9E2、9F4、11B2、4D3和4D10)只与PRL-3反应,其中4株特异性单抗可以与哺乳动物细胞表达的PRL-3反应;单抗9D8、9E2、9F4和11B2可以和PRL-3羧基末端(162-173位氨基酸)的短肽结合;4D3和4D10与中间部分(69~95位氨基酸)的短肽结合.结论 抗体9D8、9E2、9F4、11B2、4D3和4D10特异性强、亲和力高,为临床检测提供了可靠工具,并为进一步的功能研究奠定了基础.%Objective To prepare and identify specific Phosphatase of Regenerating Liver-3 (PRL-3) mon-oclonal antibodies for clinical detection and for further therapeutic intervention. Methods Hybridoma technology was used to prepare PRL-3 monocloual antibodies (MAbs), and the specificities of MAbs a-gainst PRL-3 were evaluated by Western blot and immunoprecipation. Six truncations of PRL-3 were cloned and expressed in prokaryotic cell for identifying the approximate epitope. The binding abilities of MAbs were analyzed by Western blot. Results Among 9 hybridoma clones obtained, 6 (9D8, 9E2,9F4, 11B2, 4D3 and 4D10)could specifically bind to PRL-3, and 4 could react to PRL-3 protein in eu-karyotic cells. Clone 9138,9E2,9F4 and 11B2. cloud bind to the COOH-terrninal of PRL-3, and clone 4D3 and 4D10 cloud bind to 69~95 amino acids. Conclusion MAbs 9D8, 9E2, 9F4, 11B2, 4D3 and 4D10 can react only to PRL-3, which provides potential applications in clinical diagnosis and in future study.

  20. Interaction with Tap42 Is Required for the Essential Function of Sit4 and Type 2A Phosphatases

    Wang, Huamin; Wang, Xiaodong; Jiang, Yu

    2003-01-01

    In Saccharomyces cerevisiae, Pph21 and Pph22 are the two catalytic subunits of type 2A phosphatase (PP2Ac), and Sit4 is a major form of 2A-like phosphatase. The function of these phosphatases requires their association with different regulatory subunits. In addition to the conventional regulatory subunits, namely, the A and B subunits for Pph21/22 and the Sap proteins for Sit4, these phosphatases have been found to associate with a protein termed Tap42. In this study, we demonstrated that Sit...

  1. Control of placental alkaline phosphatase gene expression in HeLa cells: induction of synthesis by prednisolone and sodium butyrate

    HeLa S3 cells produce an alkaline phosphatase indistinguishable from the enzyme from human term placenta. The phosphatase activity in these cells was induced by both prednisolone and sodium butyrate. Both agents stimulated de novo synthesis of the enzyme. The increase in phosphatase activity paralleled the increase in immunoactivity and biosynthesis of placental alkaline phosphatase. The fully processed phosphatase monomer in control, prednisolone-treated or butyrate-treated cells was a 64.5 K polypeptide, measured by both incorporation of L-[35S]methionine into enzyme protein and active-site labeling. The 64.5K polypeptide was formed by the incorporation of additional N-acetylneuraminic acid moieties to a precursor polypeptide of 61.5K. However, this biosynthetic pathway was identified only in butyrate-treated cells. In prednisolone-treated cells, the processing of 61.5K to 64.5K monomer was accelerated, and the presence of the 61.5 precursor could only be detected by either neuraminidase or monensin treatment. Phosphatase mRNA which comigrated with the term placental alkaline phosphatase mRNA of 2.7 kilobases was induced in the presence of either prednisolone or butyrate. Alkaline phosphatase mRNA is untreated HeLa S3 cells migrated slightly faster than the term placental alkaline phosphatase mRNA. Butyrate also induced a second still faster migrating alkaline phosphatase mRNA. Both prednisolone and butyrate increased the steady-state levels of placental alkaline phosphatase mRNA. The data indicate that the increase in phosphatase mRNA by prednisolone and butyrate resulted in the induction of alkaline phosphatase activity and biosynthesis in HeLa S3 cells. Furthermore, both agents induced the expression of different alkaline phosphatase gene transcripts without altering its protein product

  2. Protein phosphatases acting on the replication checkpoint

    Conde, Rui Miguel Esteves Antunes Seabra

    2010-01-01

    A génese de um cancro está dependente da acumulação de mutações genéticas que dão origem a instabilidade genómica, que por sua vez resulta na proliferação descontrolada. Para prevenir a acumulação destas mutações, as células têm mecanismos de controlo (checkpoints) que suspendem o ciclo celular e accionam as vias de reparação do ADN. Estes eventos são muitas vezes regulados por dinâmicas de (des)fosforilação de proteínas. As proteínas fosfatases (PPs), enzimas responsáveis p...

  3. A Novel Sit4 Phosphatase Complex Is Involved in the Response to Ceramide Stress in Yeast

    Alexandra Woodacre; Lone, Museer A.; Daniel Jablonowski; Roger Schneiter; Flaviano Giorgini; Raffael Schaffrath

    2013-01-01

    Ceramide is a building block for complex sphingolipids in the plasma membrane, but it also plays a significant role in secondary signalling pathways regulating cell proliferation and apoptosis in response to stress. Ceramide activated protein phosphatase activity has been previously observed in association with the Sit4 protein phosphatase. Here we find that sit4Δ mutants have decreased ceramide levels and display resistance to exogenous ceramides and phytosphingosine. Mutants lacking SIT4 or...

  4. Protein phosphatase 2a (PP2A binds within the oligomerization domain of striatin and regulates the phosphorylation and activation of the mammalian Ste20-Like kinase Mst3

    Jones Candace A

    2011-10-01

    Full Text Available Abstract Background Striatin, a putative protein phosphatase 2A (PP2A B-type regulatory subunit, is a multi-domain scaffolding protein that has recently been linked to several diseases including cerebral cavernous malformation (CCM, which causes symptoms ranging from headaches to stroke. Striatin association with the PP2A A/C (structural subunit/catalytic subunit heterodimer alters PP2A substrate specificity, but targets and roles of striatin-associated PP2A are not known. In addition to binding the PP2A A/C heterodimer to form a PP2A holoenzyme, striatin associates with cerebral cavernous malformation 3 (CCM3 protein, the mammalian Mps one binder (MOB homolog, Mob3/phocein, the mammalian sterile 20-like (Mst kinases, Mst3, Mst4 and STK25, and several other proteins to form a large signaling complex. Little is known about the molecular architecture of the striatin complex and the regulation of these sterile 20-like kinases. Results To help define the molecular organization of striatin complexes and to determine whether Mst3 might be negatively regulated by striatin-associated PP2A, a structure-function analysis of striatin was performed. Two distinct regions of striatin are capable of stably binding directly or indirectly to Mob3--one N-terminal, including the coiled-coil domain, and another more C-terminal, including the WD-repeat domain. In addition, striatin residues 191-344 contain determinants necessary for efficient association of Mst3, Mst4, and CCM3. PP2A associates with the coiled-coil domain of striatin, but unlike Mob3 and Mst3, its binding appears to require striatin oligomerization. Deletion of the caveolin-binding domain on striatin abolishes striatin family oligomerization and PP2A binding. Point mutations in striatin that disrupt PP2A association cause hyperphosphorylation and activation of striatin-associated Mst3. Conclusions Striatin orchestrates the regulation of Mst3 by PP2A. It binds Mst3 likely as a dimer with CCM3 via

  5. Catalytic DNA with phosphatase activity

    Chandrasekar, Jagadeeswaran; Silverman, Scott K.

    2013-01-01

    Catalytic DNA sequences (deoxyribozymes, DNA enzymes, or DNAzymes) have been identified by in vitro selection for various catalytic activities. Expanding the limits of DNA catalysis is an important fundamental objective and may facilitate practical utility of catalysts that can be obtained from entirely unbiased (random) sequence populations. In this study, we show that DNA can catalyze Zn2+-dependent phosphomonoester hydrolysis of tyrosine and serine side chains (i.e., exhibit phosphatase ac...

  6. Essential role of PH domain and leucine-rich repeat protein phosphatase 2 in Nrf2 suppression via modulation of Akt/GSK3β/Fyn kinase axis during oxidative hepatocellular toxicity.

    Rizvi, F; Shukla, S; Kakkar, P

    2014-01-01

    Instances of sustained oxidative activity have been shown to involve dysregulation of Nrf2-mediated transcriptional induction; however, mechanisms warranting Nrf2-repression remain unclear. In this study, using primary rat hepatocytes, we have attempted to identify factors that may negatively influence Nrf2 survival pathway. Though studies indicate a conspicuous association between Akt and Nrf2, a confirmatory link between the two is unaddressed. On inhibiting PI3K/Akt pathway, we observed compromised activities of antioxidant and detoxification enzymes culminating in oxidative cytotoxicity. This was accompanied by reduced nuclear retention of Nrf2 and its ARE binding affinity, increased Nrf2 ubiquitination and concurrent decline in its downstream targets. Moreover, Akt inhibition enhanced nuclear translocation as well as phosphorylation of Fyn kinase, an enzyme linked to Nrf2 degradation, by relieving GSK3β from phosphorylation-mediated repression. The involvement of Akt and Fyn kinase in influencing Nrf2 signaling was further confirmed in oxidatively stressed hepatocytes by using tert-butyl hydroperoxide (tBHP). tBHP-induced decrease in Nrf2 levels was associated with enhanced Fyn kinase phosphorylation, Fyn kinase nuclear translocation and decreased levels of phosphorylated GSK3β(Ser9) in a time-dependent manner. Interestingly, tBHP induced site-specific deactivation of Akt as only Akt(Ser473) phosphorylation was observed to be affected. Further, protein expression as well as nuclear localization of PHLPP2, a phosphatase specific for Akt(Ser473), was found to be significantly enhanced in tBHP-stressed hepatocytes. Silencing of PHLPP2 not only resulted in considerable restoration of Nrf2 signaling, enhanced Nrf2-ARE binding and reduced Nrf2 ubiquitination but also significantly suppressed tBHP-induced ROS generation and alterations in mitochondrial permeability. We infer that cellular PHLPP2 levels may aggravate oxidative toxicity by suppressing Nrf2/ARE

  7. Rapid Determination of Diarrhetic Shellfish Poisoning in Shellfish by Colorimetric Protein Phosphatase Inhibition Assay%磷酸酶抑制比色法快速测定贝类中腹泻性贝毒素

    郭萌萌; 吴海燕; 薛瑞宇; 谭志军; 李兆新; 翟毓秀

    2014-01-01

    基于腹泻性贝毒素(Diarrhetic shellfish poisoning,DSP)的致腹泻性组分大田软海绵酸(okadaic acid,OA)及其衍生物鳍藻毒素(dinophysistoxins,DTXs)能抑制蛋白磷酸酶活性的特点,建立了快速测定贝类中DSP的磷酸酶抑制比色分析方法.采用对硝基苯磷酸二钠(p-nitrophenyl phosphate disodium,p-NPP)为底物,其与蛋白磷酸酶2A(protein phosphatase 2A,PP2A)反应生成的黄色水解产物在碱性条件下于405 nm波长处有强烈的吸收峰,根据吸光废值计算抑制剂的浓度.酶抑制法继承了小鼠生物法能建立剂量-效应关系的优势,直接反映毒素的相对毒性大小,测定的是DSP毒素致腹泻性成分的总量,以OA浓度计.本研究优化了样品前处理方法并考察了基质浓度的影响.方法的筛选检出限为80 μg/kg.采用该方法进行加标回收实验,回收率在90.43%~118.52%范围内,相对标准偏差(RSD)为6.85%~13.93%.该方法操作简便、快捷,回收率高,重现性好,可作为快速筛查工具用于贝毒的日常监控.

  8. A new family of phosphoinositide phosphatases in microorganisms: identification and biochemical analysis

    Bennett Hayley J

    2010-08-01

    Full Text Available Abstract Background Phosphoinositide metabolism is essential to membrane dynamics and impinges on many cellular processes, including phagocytosis. Modulation of phosphoinositide metabolism is important for pathogenicity and virulence of many human pathogens, allowing them to survive and replicate in the host cells. Phosphoinositide phosphatases from bacterial pathogens are therefore key players in this modulation and constitute attractive targets for chemotherapy. MptpB, a virulence factor from Mycobacterium tuberculosis, has phosphoinositide phosphatase activity and a distinct active site P-loop signature HCXXGKDR that shares characteristics with eukaryotic lipid phosphatases and protein tyrosine phosphatases. We used this P-loop signature as a "diagnostic motif" to identify related putative phosphatases with phosphoinositide activity in other organisms. Results We found more than 200 uncharacterised putative phosphatase sequences with the conserved signature in bacteria, with some related examples in fungi and protozoa. Many of the sequences identified belong to recognised human pathogens. Interestingly, no homologues were found in any other organisms including Archaea, plants, or animals. Phylogenetic analysis revealed that these proteins are unrelated to classic eukaryotic lipid phosphatases. However, biochemical characterisation of those from Listeria monocytogenes and Leishmania major, demonstrated that, like MptpB, they have phosphatase activity towards phosphoinositides. Mutagenesis studies established that the conserved Asp and Lys in the P-loop signature (HCXXGKDR are important in catalysis and substrate binding respectively. Furthermore, we provide experimental evidence that the number of basic residues in the P-loop is critical in determining activity towards poly-phosphoinositides. Conclusion This new family of enzymes in microorganisms shows distinct sequence and biochemical characteristics to classic eukaryotic lipid phosphatases

  9. Expression of Non-Structural Protein 2C of Foot-and-mouth Disease Virus in Insect Cells and Its Application%口蹄疫病毒非结构蛋白2C基因在昆虫细胞中的表达及应用

    张小丽; 卢曾军; 马小军; 曹轶梅; 付元芳; 刘在新; 谢庆阁

    2011-01-01

    In recent years, the potential value of nonstructural protein (NSP) 2C was well documented for distinguishing foot-and-mouth disease virus (FMDV) infected animals from vaccinated animals. In this study, 2C gene of FMDV was cloned into baculovirus transfer vector pFast-bac-HT-B, and then the recombinant vectors were transformed into DHlOBac which contain backbone Bacmid. The white colonies were selected and Bacmid-2C recombinant vectors were used for transfection of Sf9 cells. After three times amplification of the viral stocks, the NSP-2C was expressed in High Five cells. The SDS-PAGE showed that a 38. 93 kD fusion protein 2C was successfully expressed, and the products showed a specific reactivity with serum from FMDV infected animal using Western-blot analysis and Dot-ELISA. An indirect ELISA based on fusion pro-tein 2C was developed, the results showed that this 2C-ELISA not only could be applied to distinguish FMDV infected animals from vaccinated animals, but also could be used to detect early anti-2C antibodies in cattle and pigs which had been infected with FMDV. The baculovirus expressed 2C appears to be a suitable antigen for the development of a reliable diagnostic test. This study make a good foundation for development of diagnosis method for detection of antibodies against multiple NSPs to discriminate the FMDV infected animals from vaccinated ones, and this will increase our capability to check the infectious virus carrier and finally improve FMDV infection control.%研究口蹄疫病毒(FMDV)非结构蛋白(NSP) 2C在区分灭活疫苗免疫动物与自然感染动物方面的意义.本研究将FMDV NSP 2C基因,克隆到穿梭载体pFast-bac- HT-B,将其转入含骨架载体Bacmid的DH10Bac,经蓝白斑筛选得到重组骨架质粒Bacmid-2C.将Bacmid-2C转染昆虫细胞Sf9,鉴定正确后,经3次增殖获得高滴度的P-3代病毒后,在High Five细胞中进行目的蛋白的表达.SDS-PAGE结果显示在High Five细胞中得到

  10. Tartrate-resistant acid phosphatase (TRAP) co-localizes with receptor activator of NF-KB ligand (RANKL) and osteoprotegerin (OPG) in lysosomal-associated membrane protein 1 (LAMP1)-positive vesicles in rat osteoblasts and osteocytes

    Solberg, L. B.; Stang, E.; Brorson, S.-H.; Andersson, G; Reinholt, F.P.

    2014-01-01

    Tartrate-resistant acid phosphatase (TRAP) is well known as an osteoclast marker; however, a recent study from our group demonstrated enhanced number of TRAP + osteocytes as well as enhanced levels of TRAP located to intracellular vesicles in osteoblasts and osteocytes in experimental osteoporosis in rats. Such vesicles were especially abundant in osteoblasts and osteocytes in cancellous bone as well as close to bone surface and intracortical remodeling sites. To further investigate TRAP in o...

  11. PURIFICATION AND PARTIAL CHARACTERIZATION OF AN ACID PHOSPHATASE FROM SPIRODELA OLIGORRHIZA AND ITS AFFINITY FOR SELECTED ORGANOPHOSPHATE PESTICIDES

    An acid phosphatase from the aquatic plant Spirodela oligorrhiza (duckweed) was isolated by fast protein liquid chromatography (FPLC) and partially characterized. The enzyme was purified 1871-fold with a total yield of 40%. SDS-PAGE electrophoresis of the pure acid phosphatase ...

  12. The wip1 phosphatase (PPM1D) antagonizes activation of the CHK2 tumor suppressor kinase

    ). Our group previously demonstrated that type 2C protein phosphatases (PP2C) Ptc2 and Ptc3 are required for DNA checkpoint inactivation after DNA double-strand break repair or adaptation in S. cerevisiae. Here we show the conservation of this pathway in mammalian cells. In response to DNA damage, ATM (ataxia telangiectasia mutated) phosphorylates the Chk2 tumor suppressor kinase at threonine 68 (Thr68), allowing Chk2 kinase dimerization and activation by auto-phosphorylations in the T-loop. The oncogenic protein Wip1, a PP2C phosphatase, binds Chk2 and de-phosphorylates phospho-Thr68. Consequently, Wip1 opposes Chk2 activation by ATM after ionizing irradiation of cells. The recombinant Chk2 protein is fully phosphorylated and activated, due to the high protein concentrations obtained during production. In vitro, Wip 1 de-phosphorylates the phospho-T68 of Chk2, but does not reduce Chk2 kinase activity on its usual GST-CDC25C substrate. These observations suggest that Wip1 phosphatase controls Chk2 activation rather than its enzymatic activity that relies on phosphorylations in the T-loop. The physiological consequences of Wip1 overexpression were tested in human adenocarcinoma cells: the HCT15 cell line. The specificities of this cell line are (i ) the absence of functional p53 proteins, leading to a G2 delay in response to a genotoxic stress, and (ii) the absence of functional Chk2 proteins, because of one CHK2 allele being unexpressed and because the second allele codes for a mutated protein that is unstable and inactive. The HCT15 cell line was complemented by a functional form of HA-Chk2 and the selected clone expresses the protein to a level similar to that observed in other cell lines. In HCT15 colorectal cancer cells corrected for functional Chk2 activity, Wip 1 modest overexpression suppressed the contribution of Chk2 to the G2/M DNA damage checkpoint. These results indicate that Wip1 is one of the phosphatases regulating the activity of Chk2 in response to DNA

  13. Main: 1I2C [RPSD[Archive

    Full Text Available Molecule: Sulfolipid Biosynthesis Protein Sqd1; Chain: A; Engineered: Yes; Mutation: Yes Biosynthetic Protei... Formation Of The Sulfonic Acid Product In The Crystalline State. To Be Published Sdr, Short-Chain Dehydroge...IHDRISRWKALTGKSIELYVGDICDFEFLAESFKSFEPDSVVHFGEQRSAPYSMIDRSRAVYTQHNNVIGTLNVLFAIKEFGEECHLVKLGTMGEYGTPNIDIEEGYI...FCVQAAVGHPLTVYGKGGQTRGYLDIRDTVQCVEIAIANPAKAGEFRVFNQFTEQFSVNELASLVTKAGSKLGLDVKKMTVPNPRVEAEEHYYNAKHTKLMELGLEPHYLSDSLLDSLLNFAVQFKDRVDTKQIMPSVSWKKIGVKTKSMTT arabi_1I2C.jpg ...

  14. Human keratinocyte ATP2C1 localizes to the Golgi and controls Golgi Ca2+ stores

    Behne, M J; Tu, Chia-Ling L; Aronchik, I; Epstein, E; Bench, G.; Bikle, D D; Pozzan, T; Mauro, T.M.

    2003-01-01

    Hailey-Hailey disease (MIM16960) is a blistering skin disease caused by mutations in the Ca2+ ATPase ATP2C1. We found that the abnormal Ca2+ signaling seen in Hailey-Hailey disease keratinocytes correlates with decreased protein levels of ATP2C1. Human ATP2C1 protein approximated 115 kDa in size. The ATP2C1 is localized to the Golgi apparatus in human keratinocytes, similar to its localization in yeast and Caenorhabditis elegans. To test whether the ATP2C1 controls Golgi Ca2+ stores, we measu...

  15. The E8̂E2C Protein, a Negative Regulator of Viral Transcription and Replication, Is Required for Extrachromosomal Maintenance of Human Papillomavirus Type 31 in Keratinocytes

    Stubenrauch, F.; Hummel, M.; Iftner, T; Laimins, L A

    2000-01-01

    The viral E2 protein is a major regulator of papillomavirus DNA replication. An important way to influence viral replication is through modulation of the activity of the E2 protein. This could occur through the action of truncated E2 proteins, called E2 repressors, whose role in the replication cycle of human papillomaviruses (HPVs) has not been determined. In this study, using cell lines that contain episomal copies of the “high-risk” HPV type 31 (HPV31), we have identified viral transcripts...

  16. Characterization of the phosphatidylinositol-glycan membrane anchor of human placental alkaline phosphatase

    Placental alkaline phosphatase [orthophosphoric-monoester phosphohydrolase (alkaline optimum), EC 3.1.3.1] is a member of a diverse group of membrane proteins whose attachment to the lipid bilayer is mediated by a phosphatidylinositol-glycan. To investigate structural aspects of the glycolipid anchor, cultured WISH cells were used because, they produce the enzyme in abundant quantities. When cell suspensions were incubated with purified phosphatidylinositol-specific phospholipase C, most of the placental alkaline phosphatase was released from membranes in a hydrophilic form. On incubation of the cells with [14C]ethanolamine, [14C]myristic acid, or myo[3H]inositol, each was incorporated into the phosphatase near the carboxyl terminus, showing that these components, which are found in other phosphatidylinositol membrane-linked proteins, are also present in placental alkaline phosphatase

  17. 23. Establishment of two transgenic cells stable expression of human cytochrome P450 2C

    2001-01-01

    AIM: To clone the human cytochrome P450 2C9 (CYP2C9) and CYP2C18 cDNA and establish two transgenic CHL cell line stable expressing human CYP2C9 and CYP2C18. METHODS:Extracting total RNA from human liver tissue, the human CYP2C9 and CYP2C18 cDNA was amplified with reverse transcription polymerase chain reaction (RT-PCR), and cloned into cloning vector pGEM-T. The cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. Two transgenic cell line were established by transfecting the recombinant vectors of pREP9-CYP2C9 and pREP9-CYP2C18 to Chinese hamster lung cell CHL. The enzyme activity of CYP2C9 and CYP2C18 catalyze tolbutamide to 4-hydroxy tolbutamide in S9 protein of the cells were determinated by HPLC. RESULTS: The sequence of the two cDNA segments cloned, which were 1540 bp and 1671 bp in length, were identical to those reported by Romkes et al(GenBank accession number: M61855, M61856, J05326) in coding amino acids. The S9 fraction of the established cell lines can metabolize tolbutamide to 4-hydroxy tolbutamide, the tolbutamide-4-hydroxylase activity was found to be 0.465±0.109 and 0.509±0.052 nmol*min-1*(mg S9 protein)-1 (n=3), but was not detectable in parental CHL cell. CONCLUSION: The cDNA of CYP2C9 and CYP2C18 were successfolly cloned and cell lines of CHL-CYP2C9 and CHL-CYP2C18 which efficiently expressed the protein of CYP2C9 and CYP2C18 were established.

  18. Tartrate resistant acid phosphatase in the immune and nervous system : Distribution and pathophysiological implications

    Lång, Pernilla

    2007-01-01

    Tartrate resistant acid phosphatase (TRAP) belongs to the family of purple acid phosphatases (PAP). It is a glycoprotein synthesized as a monomer with low enzyme activity containing a redox active diiron centre in the active site. Post-translational proteolytic processing of this monomer into a dimeric protein increases the enzyme activity. Traditionally, TRAP has been used as a marker for bone resorbing cells but the biological function of TRAP is still not fully elucidated...

  19. Part I---Evaluating Effects of Oligomer Formation on Cytochrome P450 2C9 Electron Transfer and Drug Metabolism, Part II---Utilizing Molecular Modeling Techniques to Study the Src-Interacting Proteins Actin Filament Associated Protein of 110 kDa (AFAP-110) and Cortactin

    Jett, John Edward, Jr.

    The dissertation has been divided into two parts to accurately reflect the two distinct areas of interest pursued during my matriculation in the School of Pharmacy at West Virginia University. In Part I, I discuss research probing the nature of electron transfer in the Cytochrome P450 family of proteins, a group of proteins well-known for their role in drug metabolism. In Part II, I focus on in silico and in vitro work developed in concert to probe protein structure and protein-protein interactions involved in actin filament reorganization and cellular motility. Part I. Cytochrome P450s (P450s) are an important class of enzymes known to metabolize a variety of endogenous and xenobiotic compounds. P450s are most commonly found in liver and intestinal endothelial cells and are responsible for the metabolism of approximately 75% of pharmaceutical drugs on the market. CYP2C9---one of the six major P450 isoforms---is responsible for ˜20% of drug metabolism. Elucidation of the factors that affect in vitro drug metabolism is crucial to the accurate prediction of in vivo drug metabolism kinetics. Currently, the two major techniques for studying in vitro drug metabolism are solution-based. However, it is known that the results of solution-based studies can vary from in vivo drug metabolism. One reason suggested to account for this variation is the state of P450 oligomer formation in solution compared to the in vivo environment, where P450s are membrane-bound. To understand the details of how oligomer formation affects in vitro drug metabolism, it is imperative that techniques be developed which will allow for the unequivocal control of oligomer formation without altering other experimental parameters. Our long term goal of this research is to develop methods to more accurately predict in vivo drug metabolism from in vitro data. This section of the dissertation will discuss the development of a platform consisting of a doped silicon surface containing a large array of gold

  20. Detection of endogenous alkaline phosphatase activity in intact cells by flow cytometry using the fluorogenic ELF-97 phosphatase substrate

    Telford, W. G.; Cox, W. G.; Stiner, D.; Singer, V. L.; Doty, S. B.

    1999-01-01

    BACKGROUND: The alkaline phosphatase (AP) substrate 2-(5'-chloro-2'-phosphoryloxyphenyl)-6-chloro-4-(3H)-quinazolinone (ELF((R))-97 for enzyme-labeled fluorescence) has been found useful for the histochemical detection of endogenous AP activity and AP-tagged proteins and oligonucleotide probes. In this study, we evaluated its effectiveness at detecting endogenous AP activity by flow cytometry. METHODS: The ELF-97 phosphatase substrate was used to detect endogenous AP activity in UMR-106 rat osteosarcoma cells and primary cultures of chick chondrocytes. Cells were labeled with the ELF-97 reagent and analyzed by flow cytometry using an argon ultraviolet (UV) laser. For comparison purposes, cells were also assayed for AP using a Fast Red Violet LB azo dye assay previously described for use in detecting AP activity by flow cytometry. RESULTS: The ELF-97 phosphatase substrate effectively detected endogenous AP activity in UMR-106 cells, with over 95% of the resulting fluorescent signal resulting from AP-specific activity (as determined by levamisole inhibition of AP activity). In contrast, less than 70% of the fluorescent signal from the Fast Red Violet LB (FRV) assay was AP-dependent, reflecting the high intrinsic fluorescence of the unreacted components. The ELF-97 phosphatase assay was also able to detect very low AP activity in chick chondrocytes that was undetectable by the azo dye method. CONCLUSIONS: The ELF-97 phosphatase assay was able to detect endogenous AP activity in fixed mammalian and avian cells by flow cytometry with superior sensitivity to previously described assays. This work also shows the applicability of ELF-97 to flow cytometry, supplementing its previously demonstrated histochemical applications. Copyright 1999 Wiley-Liss, Inc.

  1. Discovery and development of small molecule SHIP phosphatase modulators.

    Viernes, Dennis R; Choi, Lydia B; Kerr, William G; Chisholm, John D

    2014-07-01

    Inositol phospholipids play an important role in the transfer of signaling information across the cell membrane in eukaryotes. These signals are often governed by the phosphorylation patterns on the inositols, which are mediated by a number of inositol kinases and phosphatases. The src homology 2 (SH2) containing inositol 5-phosphatase (SHIP) plays a central role in these processes, influencing signals delivered through the PI3K/Akt/mTOR pathway. SHIP modulation by small molecules has been implicated as a treatment in a number of human disease states, including cancer, inflammatory diseases, diabetes, atherosclerosis, and Alzheimer's disease. In addition, alteration of SHIP phosphatase activity may provide a means to facilitate bone marrow transplantation and increase blood cell production. This review discusses the cellular signaling pathways and protein-protein interactions that provide the molecular basis for targeting the SHIP enzyme in these disease states. In addition, a comprehensive survey of small molecule modulators of SHIP1 and SHIP2 is provided, with a focus on the structure, potency, selectivity, and solubility properties of these compounds. PMID:24302498

  2. PTP-PEST phosphatase variations in human cancer.

    Streit, Sylvia; Ruhe, Jens Ernst; Knyazev, Pjotr; Knyazeva, Tatjana; Iacobelli, Stefano; Peter, Stephan; Hoefler, Heinz; Ullrich, Axel

    2006-10-01

    Signal transduction via tyrosine phosphorylation, normally fine-tuned by the concerted action of both protein tyrosine kinases and protein tyrosine phosphatases (PTPs), is a key mechanism in tumorigenesis. PTP-PEST, a ubiquitously expressed cytoplasmic tyrosine phosphatase, is thought to play an important role in cell adhesion and motility, and may be involved in metastasis. A search for sequence variations within the gene PTPN12 (alias PTP-PEST) was performed in breast cancer cell lines, leading to the identification of three amino acid substitutions at positions 322, 573, and 709. These alterations were also found in squamous cell carcinoma cell lines and could be verified in primary human breast and kidney tumor samples. Analysis of peripheral blood samples confirmed the germline origin of these alterations. Furthermore, functional characterization of the Ile322 and Ala573 PTP-PEST mutants revealed an enhancement of in vitro phosphatase activity, whereas the Lys709 variant showed reduced catalytic activity. These data demonstrate the existence of PTP-PEST variants that might be meaningful for human cancer and underscore the need for further characterizing PTP-PEST and its signaling pathways in context of this disease. PMID:16965954

  3. Structural and functional insights into CYP2C8.3:A genetic polymorph of cytochrome P450 2C8

    2010-01-01

    The cytochrome P450 (CYP) superfamily plays a key role in the oxidative metabolism of a wide range of exogenous chemicals. CYP2C8 is the principal enzyme responsible for the metabolism of the anti-cancer drug paclitaxel in the human liver, and carries out the oxidative metabolism of at least 5% of clinical drugs. Polymorphisms in CYP2C8 have been closely implicated in individualized medication. CYP2C8.3, a common polymorph of CYP2C8 with dual amino acid substitutions R139K and K399R, is found primarily in Caucasians. In this study, CYP2C8.3 and its wild type (WT) CYP2C8 were expressed in E. coli, and their purified proteins were characterized by UV-visible spectroscopy, mass spectrometry, and circular dichroism. Their thermal stability, substrate binding ability, and metabolic activity against paclitaxel were investigated. The electron transfer kinetics during paclitaxel metabolism by WT CYP2C8 or CYP2C8.3 was studied by stopped-flow kinetics. The results revealed that mutations in CYP2C8.3 did not greatly influence the heme active site or protein thermal stability and paclitaxel binding ability, but the metabolic activity against paclitaxel was significantly depressed to just 11% of that of WT CYP2C8. Electron transfer from CYP reductase to CYP2C8.3 was found to be significantly slower than that to WT CYP2C8 during catalysis, and this might be the main reason for the depressed metabolic activity. Since the polymorph CYP2C8.3 is defective in catalyzing substrates of CYP2C8 in vitro, it might be expected to have important clinical and pathophysiological consequences in homozygous individuals, and this study provides valuable information in this aspect.

  4. PROTEN TYROSINE PHOSPHATASE ACTIVITY IN RAT ASCITES HEPATOMA CELLS

    M.Saadat

    1998-10-01

    Full Text Available Protein tyrosine phosphatases (PTPases regulate tyrosine phosphorylation of target proteins involved in several aspects of cellular functions. Enzyme activities of the PTPases in cytosolic and particulate fractions of rat ascites hepatoma cell lines were determined and compared with those of normal rat liver. Our present data revealed that although there was no neoplatic-specific alteration of the PTPase activity in examined hepatomas, the activity in particulate fractions of island type of hepatomas was remarkably decreased compared with either rat liver or free type hepatomas.

  5. MKP-8, a novel MAPK phosphatase that inhibits p38 kinase

    Intracellular signaling pathways and their relationship to malignant progression have become a major focus of cancer biology. The dual-specificity phosphatase (DSP) family is a more recently identified family of intracellular signaling modulators. We have identified a novel protein phosphatase with a well-conserved DSP catalytic domain containing the DSP catalytic motif, xHCxxGxSRS, and mitogen-activated protein kinase phosphatase (MKP) motif, AYLM. Because of these unique characteristics, the protein was named mitogen-activated protein kinase phosphatase-8 (MKP-8). This protein is approximately 20 kDa in size and mainly localizes to the nuclear compartment of the cell. MKP-8 is expressed in embryonal cancers (retinoblastoma, neuroepithelioma, and neuroblastoma) and has limited expression in normal tissues. MKP-8 displays significant phosphatase activity that is inhibited by a cysteine to serine substitution in the catalytic domain. When co-expressed with activated MAPKs, MKP-8 is able to inhibit p38 kinase phosphorylation and downstream activity

  6. Nucleotide and amino acid sequences of human intestinal alkaline phosphatase: close homology to placental alkaline phosphatase

    A cDNA clone for human adult intestinal alkaline phosphatase (ALP) [orthophosphoric-monoester phosphohydrolase (alkaline optimum); EC 3.1.3.1] was isolated from a λgt11 expression library. The cDNA insert of this clone is 2513 base pairs in length and contains an open reading frame that encodes a 528-amino acid polypeptide. This deduced polypeptide contains the first 40 amino acids of human intestinal ALP, as determined by direct protein sequencing. Intestinal ALP shows 86.5% amino acid identity to placental (type 1) ALP and 56.6% amino acid identity to liver/bone/kidney ALP. In the 3'-untranslated regions, intestinal and placental ALP cDNAs are 73.5% identical (excluding gaps). The evolution of this multigene enzyme family is discussed

  7. Expression and Characterization of Recombinant Thermostable Alkaline Phosphatase from a Novel Thermophilic Bacterium Thermus thermophilus XM

    Jianbo LI; Limei XU; Feng YANG

    2007-01-01

    A gene (tap) encoding a thermostable alkaline phosphatase from the thermophilic bacterium Thermus thermophilus XM was cloned and sequenced. It is 1506 bp long and encodes a protein of 501 amino acid residues with a calculated molecular mass of 54.7 kDa. Comparison of the deduced amino acid sequence with other alkaline phosphatases showed that the regions in the vicinity of the phosphorylation site and metal binding sites are highly conserved. The recombinant thermostable alkaline phosphatase was expressed as a His6-tagged fusion protein in Escherichia coli and its enzymatic properties were characterized after purification. The pH and temperature optima for the recombinant thermostable alkaline phosphatases activity were pH 12 and 75 ℃. As expected, the enzyme displayed high thermostability, retaining more than 50% activity after incubating for 6 h at 80 ℃. Its catalytic function was accelerated in the presence of 0.1 mM Co2+, Fe2+, Mg2+, or Mn2+ but was strongly inhibited by 2.0 mM Fe2+. Under optimal conditions, the Michaelis constant (Km) for cleavage of p-nitrophenyl-phosphate was 0.034 mM. Although it has much in common with other alkaline phosphatases, the recombinant thermostable alkaline phosphatase possesses some unique features, such as high optimal pH and good thermostability.

  8. Cloning and sequencing of human intestinal alkaline phosphatase cDNA

    Partial protein sequence data obtained on intestinal alkaline phosphatase indicated a high degree of homology with the reported sequence of the placental isoenzyme. Accordingly, placental alkaline phosphatase cDNA was cloned and used as a probe to clone intestinal alkaline phosphatase cDNA. The latter is somewhat larger (3.1 kilobases) than the cDNA for the placental isozyme (2.8 kilobases). Although the 3' untranslated regions are quite different, there is almost 90% homology in the translated regions of the two isozymes. There are, however, significant differences at their amino and carboxyl termini and a substitution of an alanine in intestinal alkaline phosphatase for a glycine in the active site of the placental isozyme

  9. PPARα activators down-regulate CYP2C7, a retinoic acid and testosterone hydroxylase

    Peroxisome proliferators (PP) are a large class of structurally diverse chemicals that mediate their effects in the liver mainly through the peroxisome proliferator-activated receptor α (PPARα). Exposure to PP results in down-regulation of CYP2C family members under control of growth hormone and sex steroids including CYP2C11 and CYP2C12. We hypothesized that PP exposure would also lead to similar changes in CYP2C7, a retinoic acid and testosterone hydroxylase. CYP2C7 gene expression was dramatically down-regulated in the livers of rats treated for 13 weeks by WY-14,643 (WY; 500 ppm) or gemfibrozil (GEM; 8000 ppm). In the same tissues, exposure to WY and GEM and to a lesser extent di-n-butyl phthalate (20 000 ppm) led to decreases in CYP2C7 protein levels in both male and female rats. An examination of the time and dose dependence of CYP2C7 protein changes after PP exposure revealed that CYP2C7 was more sensitive to compound exposure compared to other CYP2C family members. Protein expression was decreased after 1, 5 and 13 weeks of PP treatment. CYP2C7 protein expression was completely abolished at 5 ppm WY, the lowest dose tested. GEM and DBP exhibited dose-dependent decreases in CYP2C7 protein expression, becoming significant at 1000 ppm or 5000 ppm and above, respectively. These results show that PP exposure leads to changes in CYP2C7 mRNA and protein levels. Thus, in addition to known effects on steroid metabolism, exposure to PP may alter retinoic acid metabolism

  10. Dual 4- and 5-phosphatase activities regulate SopB-dependent phosphoinositide dynamics to promote bacterial entry.

    Piscatelli, Heather L; Li, Menghan; Zhou, Daoguo

    2016-05-01

    Salmonella are able to invade non-phagocytic cells such as intestinal epithelial cells by modulating the host actin cytoskeleton to produce membrane ruffles. Two type III effector proteins SopB and SopE play key roles to this modulation. SopE is a known guanine nucleotide exchange factor (GEF) capable of activating Rac1 and CDC42. SopB is a phosphatidylinositol 4-phosphatase and 5-phosphatase promoting membrane ruffles and invasion of Salmonella through undefined mechanisms. Previous studies have demonstrated that the 4-phosphatase activity of SopB is required for PtdIns-3-phosphate (PtdIns(3)P) accumulation and SopB-mediated invasion. We show here that both the 4-phosphatase as well as the 5-phosphatase activities of SopB are essential in ruffle formation and subsequent invasion. We found that the 5-phosphatase activity of SopB is likely responsible for generating PtdIns-3,4-bisphosphate (PtdIns(3,4)P2 ) and subsequent recruitment of sorting nexin 9 (SNX9), an actin modulating protein. Intriguingly, the 4-phosphatase activity is responsible for the dephosphorylation of PtdIns(3,4)P2 into PtdIns(3)P. Alone, neither activity is sufficient for ruffling but when acting in conjunction with one another, the 4-phosphatase and 5-phosphatase activities led to SNX9-mediated ruffling and Salmonella invasion. This work reveals the unique ability of bacterial effector protein SopB to utilize both its 4- and 5-phosphatase activities to regulate phosphoinositide dynamics to promote bacterial entry. PMID:26537021

  11. Biochemistry and structure of phosphoinositide phosphatases

    Young Yil Bahk

    2013-01-01

    Full Text Available Phosphoinositides are the phosphorylated derivatives ofphosphatidylinositol, and play a very significant role in adiverse range of signaling processes in eukaryotic cells. Anumber of phosphoinositide-metabolizing enzymes, includingphosphoinositide-kinases and phosphatases are involved in thesynthesis and degradation of these phospholipids. Recently,the function of various phosphatases in the phosphatidylinositolsignaling pathway has been of great interest. In thepresent review we summarize the structural insights andbiochemistry of various phosphatases in regulating phosphoinositidemetabolism. [BMB Reports 2013; 46(1: 1-8

  12. POPX2 phosphatase regulates the KIF3 kinesin motor complex.

    Phang, Hui-Qun; Hoon, Jing-Ling; Lai, Soak-Kuan; Zeng, Yukai; Chiam, Keng-Hwee; Li, Hoi-Yeung; Koh, Cheng-Gee

    2014-02-15

    The kinesin motors are important in the regulation of cellular functions such as protein trafficking, spindle organization and centrosome separation. In this study, we have identified POPX2, a serine-threonine phosphatase, as an interacting partner of the KAP3 subunit of the kinesin-2 motor. The kinesin-2 motor is a heterotrimeric complex composed of KIF3A, KIF3B motor subunits and KAP3, the non-motor subunit, which binds the cargo. Here we report that the phosphatase POPX2 is a negative regulator of the trafficking of N-cadherin and other cargoes; consequently, it markedly influences cell-cell adhesion. POPX2 affects trafficking by determining the phosphorylation status of KIF3A at serine 690. This is consistent with the observation that the KIF3A-S690A mutant is defective in cargo trafficking. Our studies also implicate CaMKII as the kinase that phosphorylates KIF3A at serine 690. These results strongly suggest that POPX2 and CaMKII are a phosphatase-kinase pair that regulates kinesin-mediated transport and cell-cell adhesion. PMID:24338362

  13. Calcineurin phosphatase activity and immunosuppression. A review on the role of calcineurin phosphatase activity and the immunosuppressive effect of cyclosporin A and tacrolimus

    Jørgensen, Kaj Anker; Koefoed-Nielsen, P.B.; Karamperis, N.

    2003-01-01

    The mode of immunosuppressive action of tacrolimus (FK506) and cyclosporin A has been elucidated. Both drugs bind to proteins in the cytoplasm to form complexes, which in turn inhibit the phosphatase activity of calcineurin, an important limiting step in the activation of T cells. The association...

  14. Developing 2 C-compatible investment criteria

    This report studies the development of criteria for assessing the compatibility of financial investments with the international goal to limit global temperature increase to below 2 C above pre-industrial levels. The findings are intended as a starting point and a key input for a longer term process to develop consensus-based 2 C investing criteria. The focus here is placed on investments in projects and physical assets, in particular of development and climate finance organisations. In order to limit global temperature increase to 2 C, global greenhouse gas (GHG) emissions will have to be reduced significantly, eventually to zero, during the course of this century. This requires shifting capital from high to low carbon investments as well as significant capital mobilisation for investments in 2 C-compatible infrastructure. Given the long lifetime of physical assets, and the urgency of decarbonisation over the coming decades, this needs to begin today. Public financial institutions can play a prominent role in contributing to aligning investment flows with the 2 C limit, as well as in closing the current infrastructure investment gap, responding to their explicit or implicit climate mandates and leadership role in the finance sector. The majority of international financial institutions integrate climate considerations into their finance decisions to some degree, and are familiar with different types of criteria, including positive and negative lists, qualitative and quantitative benchmarks, and the use of shadow carbon pricing. However, current approaches do not link to the 2 C limit. 2 C investment criteria are therefore needed to guide investors in this regard. Such criteria may also support other purposes, including an understanding of climate risks and improved reporting and accountability.

  15. Developing 2 C-compatible investment criteria

    Roeser, Frauke [NewClimate - Institute for Climate Policy and Global Sustainability gGmbH, Bonn (Germany); Weischer, Lutz [Germanwatch e.V., Koeln (Germany); Thomae, Jakob [2degrees Investing Initiative, New York, NY (United States); Hoehne, Niklas; Hagemann, Markus; El Alaoui, Alexander; Bals, Christoph; Eckstein, David; Kreft, Soenke; Rosse, Morten

    2015-11-30

    This report studies the development of criteria for assessing the compatibility of financial investments with the international goal to limit global temperature increase to below 2 C above pre-industrial levels. The findings are intended as a starting point and a key input for a longer term process to develop consensus-based 2 C investing criteria. The focus here is placed on investments in projects and physical assets, in particular of development and climate finance organisations. In order to limit global temperature increase to 2 C, global greenhouse gas (GHG) emissions will have to be reduced significantly, eventually to zero, during the course of this century. This requires shifting capital from high to low carbon investments as well as significant capital mobilisation for investments in 2 C-compatible infrastructure. Given the long lifetime of physical assets, and the urgency of decarbonisation over the coming decades, this needs to begin today. Public financial institutions can play a prominent role in contributing to aligning investment flows with the 2 C limit, as well as in closing the current infrastructure investment gap, responding to their explicit or implicit climate mandates and leadership role in the finance sector. The majority of international financial institutions integrate climate considerations into their finance decisions to some degree, and are familiar with different types of criteria, including positive and negative lists, qualitative and quantitative benchmarks, and the use of shadow carbon pricing. However, current approaches do not link to the 2 C limit. 2 C investment criteria are therefore needed to guide investors in this regard. Such criteria may also support other purposes, including an understanding of climate risks and improved reporting and accountability.

  16. Human prostatic acid phosphatase directly stimulates collagen synthesis and alkaline phosphatase content of isolated bone cells

    Human prostatic acid phosphatase (hPAP) directly enhances the differentiated characteristics of isolated bone cells in vitro. This enzyme, when added to cell cultures for 24 h in vitro stimulates collagen synthesis and the production of alkaline phosphatase. The effects are dose dependent, with statistically significant effects occurring from 0.1-100 nM hPAP. Concentrations higher than 100 nM do not evoke greater effects. The maximal effect of hPAP occurs between 12 and 24 h of exposure. The cells stimulated to the greatest degree are osteoprogenitor cells and osteoblasts. Fibroblasts isolated from the same tissue show a lesser sensitivity to hPAP. hPAP has no detectable effect on cell proliferation, as measured by radiolabeled thymidine incorporation or total DNA synthesis. None of the observations reported in this work can be attributed to contaminating proteins in the hPAP preparation. hPAP was radiolabeled with 125I and was used for affinity binding and cross-linking studies. Scatchard analysis of specific binding indicated the presence of 1.0 X 10(5) high affinity binding sites/cell, with a Kd of 6.5 nM. Cross-linking studies demonstrated the presence of one 320-kDa binding complex. The pH profile and kinetic determinations of Km and maximum velocity for hPAP were similar to those previously reported, except for the finding of positive cooperativity of the substrate with the enzyme under the conditions of our assay. We believe that the direct stimulation of bone-forming cells by hPAP may contribute to the sclerotic nature of skeletal bone around sites of neoplastic prostatic metastases and that the effect of the enzyme is probably mediated by a plasma membrane receptor

  17. 21 CFR 864.7660 - Leukocyte alkaline phosphatase test.

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Leukocyte alkaline phosphatase test. 864.7660... Leukocyte alkaline phosphatase test. (a) Identification. A leukocyte alkaline phosphatase test is a device used to identify the enzyme leukocyte alkaline phosphatase in neutrophilic granulocytes...

  18. Assessing the Biological Activity of the Glucan Phosphatase Laforin.

    Romá-Mateo, Carlos; Raththagala, Madushi; Gentry, Mathew S; Sanz, Pascual

    2016-01-01

    Glucan phosphatases are a recently discovered family of enzymes that dephosphorylate either starch or glycogen and are essential for proper starch metabolism in plants and glycogen metabolism in humans. Mutations in the gene encoding the only human glucan phosphatase, laforin, result in the fatal, neurodegenerative, epilepsy known as Lafora disease. Here, we describe phosphatase assays to assess both generic laforin phosphatase activity and laforin's unique glycogen phosphatase activity. PMID:27514803

  19. Role of polynucleotide kinase/phosphatase in mitochondrial DNA repair

    Tahbaz, Nasser; Subedi, Sudip; Weinfeld, Michael

    2012-01-01

    Mutations in mitochondrial DNA (mtDNA) are implicated in a broad range of human diseases and in aging. Compared to nuclear DNA, mtDNA is more highly exposed to oxidative damage due to its proximity to the respiratory chain and the lack of protection afforded by chromatin-associated proteins. While repair of oxidative damage to the bases in mtDNA through the base excision repair pathway has been well studied, the repair of oxidatively induced strand breaks in mtDNA has been less thoroughly examined. Polynucleotide kinase/phosphatase (PNKP) processes strand-break termini to render them chemically compatible for the subsequent action of DNA polymerases and ligases. Here, we demonstrate that functionally active full-length PNKP is present in mitochondria as well as nuclei. Downregulation of PNKP results in an accumulation of strand breaks in mtDNA of hydrogen peroxide-treated cells. Full restoration of repair of the H2O2-induced strand breaks in mitochondria requires both the kinase and phosphatase activities of PNKP. We also demonstrate that PNKP contains a mitochondrial-targeting signal close to the C-terminus of the protein. We further show that PNKP associates with the mitochondrial protein mitofilin. Interaction with mitofilin may serve to translocate PNKP into mitochondria. PMID:22210862

  20. Prophylactic treatment with alkaline phosphatase in cardiac surgery induces endogenous alkaline phosphatase release

    Kats, Suzanne; Brands, Ruud; Hamad, Mohamed A. Soliman; Seinen, Willem; Schamhorst, Volkher; Wulkan, Raymond W.; Schoenberger, Jacques P.; van Oeveren, Wim

    2012-01-01

    Introduction: Laboratory and clinical data have implicated endotoxin as an important factor in the inflammatory response to cardiopulmonary bypass. We assessed the effects of the administration of bovine intestinal alkaline phosphatase (bIAP), an endotoxin detoxifier, on alkaline phosphatase levels