1
|
Chrupcala ML, Moseley JB. PP2A-B56 regulates Mid1 protein levels for proper cytokinesis in fission yeast. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.28.601230. [PMID: 38979265 PMCID: PMC11230426 DOI: 10.1101/2024.06.28.601230] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/10/2024]
Abstract
Protein phosphorylation regulates many steps in the cell division process including cytokinesis. In the fission yeast S. pombe, the anillin-like protein Mid1 sets the cell division plane and is regulated by phosphorylation. Multiple protein kinases act on Mid1, but no protein phosphatases have been shown to regulate Mid1. Here, we discovered that the conserved protein phosphatase PP2A-B56 is required for proper cytokinesis by promoting Mid1 protein levels. We find that par1Δ cells lacking the primary B56 subunit divide asymmetrically due to the assembly of misplaced cytokinetic rings that slide toward cell tips. These par1Δ mutants have reduced whole-cell levels of Mid1 protein, leading to reduced Mid1 at the cytokinetic ring. Restoring proper Mid1 expression suppresses par1Δ cytokinesis defects. This work identifies a new PP2A-B56 pathway regulating cytokinesis through Mid1, with implications for control of cytokinesis in other organisms.
Collapse
Affiliation(s)
- Madeline L. Chrupcala
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover NH
| | - James B. Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth, Hanover NH
| |
Collapse
|
2
|
Schatten H. The Centrosome Cycle within the Cell Cycle. THE CENTROSOME AND ITS FUNCTIONS AND DYSFUNCTIONS 2022; 235:17-35. [DOI: 10.1007/978-3-031-20848-5_2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
|
3
|
Vagnarelli P. Back to the new beginning: Mitotic exit in space and time. Semin Cell Dev Biol 2021; 117:140-148. [PMID: 33810980 DOI: 10.1016/j.semcdb.2021.03.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 03/16/2021] [Accepted: 03/16/2021] [Indexed: 11/16/2022]
Abstract
The ultimate goal of cell division is to generate two identical daughter cells that resemble the mother cell from which they derived. Once all the proper attachments to the spindle have occurred, the chromosomes have aligned at the metaphase plate and the spindle assembly checkpoint (a surveillance mechanism that halts cells form progressing in the cell cycle in case of spindle - microtubule attachment errors) has been satisfied, mitotic exit will occur. Mitotic exit has the purpose of completing the separation of the genomic material but also to rebuild the cellular structures necessary for the new cell cycle. This stage of mitosis received little attention until a decade ago, therefore our knowledge is much patchier than the molecular details we now have for the early stages of mitosis. However, it is emerging that mitotic exit is not just the simple reverse of mitotic entry and it is highly regulated in space and time. In this review I will discuss the main advances in the field that provided us with a better understanding on the key role of protein phosphorylation/de-phosphorylation in this transition together with the concept of their spatial regulation. As this field is much younger, I will highlight general consensus, contrasting views together with the outstanding questions awaiting for answers.
Collapse
Affiliation(s)
- Paola Vagnarelli
- College of Medicine, Health and Life Science, Centre for Genomic Engineering and Maintenance (CenGEM), Brunel University London, Uxbridge UB8 3PH, UK.
| |
Collapse
|
4
|
Bojadzija Savic G, Colinet H, Bormans M, Edwards C, Lawton LA, Briand E, Wiegand C. Cell free Microcystis aeruginosa spent medium affects Daphnia magna survival and stress response. Toxicon 2021; 195:37-47. [PMID: 33716069 DOI: 10.1016/j.toxicon.2021.03.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 02/19/2021] [Accepted: 03/08/2021] [Indexed: 12/01/2022]
Abstract
Primary consumers in freshwater ecosystems, such as the zooplankton organism Daphnia magna, are highly affected by cyanobacteria, both as they may use it as a food source but also by cyanobacterial metabolites present in the water. Here, we investigate the impacts of cyanobacterial metabolites focussing on the environmental realistic scenario of the naturally released mixture without crushing cyanobacterial cells or their uptake as food. Therefore, D. magna were exposed to two concentrations of cell free cyanobacterial spent medium from Microcystis aeruginosa PCC 7806 to represent higher and lower ecologically-relevant concentrations of cyanobacterial metabolites. Including microcystin-LR, 11 metabolites have been detected of which 5 were quantified. Hypothesising concentration and time dependent negative impact, survival, gene expression marking digestion and metabolism, oxidative stress response, cell cycle and molting as well as activities of detoxification and antioxidant enzymes were followed for 7 days. D. magna suffered from oxidative stress as both catalase and glutathione S-transferase enzyme activities significantly decreased, suggesting enzyme exhaustibility after 3 and 7 days. Moreover, gene-expressions of the 4 stress markers (glutathione S-transferase, glutathione peroxidase, catalase and thioredoxin) were merely downregulated after 7 days of exposure. Energy allocation (expression of glyceraldehyde-3-phosphate dehydrogenase) was increased after 3 days but decreased as well after 7 days exposure. Cell cycle was impacted time dependently but differently by the two concentrations, along with an increasing downregulation of myosin heavy chain responsible for cell arrangement and muscular movements. Deregulation of nuclear hormone receptor genes indicate that D. magna hormonal steering including molting seemed impaired despite no detection of microviridin J in the extracts. As a consequence of all those responses and presumably of more than investigated molecular and physiological changes, D. magna survival was impaired over time, in a concentration dependent manner. Our results confirm that besides microcystin-LR, other secondary metabolites contribute to negative impact on D. magna survival and stress response.
Collapse
Affiliation(s)
| | - Hervé Colinet
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
| | - Myriam Bormans
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
| | - Christine Edwards
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB10 7GJ, United Kingdom.
| | - Linda A Lawton
- School of Pharmacy and Life Sciences, Robert Gordon University, Aberdeen, AB10 7GJ, United Kingdom.
| | - Enora Briand
- IFREMER, Phycotoxins Laboratory, F-44311, Nantes, France.
| | - Claudia Wiegand
- UMR ECOBIO, 6553 CNRS, Université de Rennes 1, Campus de Beaulieu, Rennes, France.
| |
Collapse
|
5
|
Xin G, Fu J, Luo J, Deng Z, Jiang Q, Zhang C. Aurora B regulates PP1γ-Repo-Man interactions to maintain the chromosome condensation state. J Biol Chem 2020; 295:14780-14788. [PMID: 32938714 DOI: 10.1074/jbc.ac120.012772] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2020] [Revised: 09/12/2020] [Indexed: 11/06/2022] Open
Abstract
The mitotic kinase Aurora B regulates the condensation of chromatin into chromosomes by phosphorylating chromatin proteins during early mitosis, whereas the phosphatase PP1γ performs the opposite function. The roles of Aurora B and PP1γ must be tightly coordinated to maintain chromosomes at a high phosphorylation state, but the precise mechanisms regulating their function remain largely unclear. Here, mainly through immunofluorescence microscopy and co-immunoprecipitation assays, we find that dissociation of PP1γ from chromosomes is essential for maintaining chromosome phosphorylation. We uncover that PP1γ is recruited to mitotic chromosomes by its regulatory subunit Repo-Man in the absence of Aurora B activity and that Aurora B regulates dissociation of PP1γ by phosphorylating and disrupting PP1γ-Repo-Man interactions on chromatin. Overexpression of Repo-Man mutants that cannot be phosphorylated or inhibition of Aurora B kinase activity resulted in the retention of PP1γ on chromatin and prolonged the chromatin condensation process; a similar outcome was caused by the ectopic targeting of PP1γ to chromatin. Together, our findings reveal a novel regulation mechanism of chromatin condensation in which Aurora B counteracts PP1γ activity by releasing PP1γ from Repo-Man and may have important implications for understanding the regulations of dynamic structural changes of the chromosomes in mitosis.
Collapse
Affiliation(s)
- Guangwei Xin
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Jingyan Fu
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Jia Luo
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Zhaoxuan Deng
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Qing Jiang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China
| | - Chuanmao Zhang
- Ministry of Education Key Laboratory of Cell Proliferation and Differentiation, College of Life Sciences, Peking University, Beijing, China.
| |
Collapse
|
6
|
Wang B, Pan LY, Kang N, Shen XY. PP4R1 interacts with HMGA2 to promote non-small-cell lung cancer migration and metastasis via activating MAPK/ERK-induced epithelial-mesenchymal transition. Mol Carcinog 2020; 59:467-477. [PMID: 32077156 DOI: 10.1002/mc.23168] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 01/26/2020] [Accepted: 02/06/2020] [Indexed: 12/21/2022]
Abstract
Protein phosphatase 4 regulatory subunit 1 (PP4R1) has been shown to play a role in the regulation of centrosome maturation, apoptosis, DNA repair, and tumor necrosis factor signaling. However, the function of PP4R1 in non-small-cell lung cancer remains unclear. In this study, we identify PP4R1 as an oncogene through Oncomine database mining and immunohistochemical staining, and we showed that PP4R1 is upregulated in lung cancer tissues as compared with that in normal lung tissues and correlated with a poor prognosis in lung cancer patients. Furthermore, in vitro study by wound-healing and Transwell assay showed that PP4R1 could promote migration and invasion of lung cancer cells. Mechanistic investigations revealed that PP4R1 could cooperate with high mobility group AT-hook 2 and thereby promotes epithelial-mesenchymal transition via MAPK/extracellular receptor kinase activation. Taken together, our study provides a rich resource for understanding PP4R1 in lung cancer and indicates that PP4R1 may serve as a potential biomarker in lung cancer therapies.
Collapse
Affiliation(s)
- Bin Wang
- Department of Thoracic Surgery, The Affiliated Huadong Hospital of Fudan University, Shanghai, China
| | - Lin-Yue Pan
- Department of Respiration, The Affiliated Huadong Hospital of Fudan University, Shanghai, China
| | - Ning Kang
- Department of Thoracic Surgery, The Affiliated Huadong Hospital of Fudan University, Shanghai, China
| | - Xiao-Yong Shen
- Department of Thoracic Surgery, The Affiliated Huadong Hospital of Fudan University, Shanghai, China
| |
Collapse
|
7
|
Al-Hazmi A. Antioxidant Activity of Silymarin in Microcystin-LR Cardiac and Pulmonary Induced Injuries on Mice. Pak J Biol Sci 2020; 23:1369-1373. [PMID: 33274863 DOI: 10.3923/pjbs.2020.1369.1373] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
BACKGROUND AND OBJECTIVES Microcystin-LR has a toxic effect on several organs causing the destruction and fibrosis of these organs. This study was done to evaluate the antioxidant activity of silymarin on some oxidative stress parameters on heart and lung injuries induced by microcystin-LR in mice. MATERIALS AND METHODS Total 72 Balb/c male mice aged between five to seven weeks were grouped into 6; Group 1 contained twelve mice which were assigned as the healthy control group (C). Two microcystin-LR control groups assigned M6 and M12 contain 12 mice each. A fourth group contains twelve mice called the silymarin control group(S). The fifth and sixth groups contain twenty-four mice assigned as microcystin-LR silymarin groups SM6 and SM12. A blood sample was collected for estimation of serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST). The homogenates of heart and lungs were extracted for estimation of protein carbonyl content (CC), lipid peroxidation products (LPO), reduced glutathione (GSH), methylglyoxal (MG) and activity of protein phosphatase I (PPI). RESULTS Significant statistical differences in both ALT and AST were observed between all groups (P>0.01). In cardiac homogenate, a significant statistical difference was observed in PPI, LPO and CC between all groups (P<0.05). Furthermore, methylglyoxal showed a significant statistical difference between all groups (p<0.01). CONCLUSION The findings suggested a potential therapeutic role of using silymarin as an antioxidant agent against cardiac and pulmonary injuries induced by MC-LR.
Collapse
|
8
|
Moura M, Conde C. Phosphatases in Mitosis: Roles and Regulation. Biomolecules 2019; 9:E55. [PMID: 30736436 PMCID: PMC6406801 DOI: 10.3390/biom9020055] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2018] [Revised: 01/31/2019] [Accepted: 02/01/2019] [Indexed: 02/07/2023] Open
Abstract
Mitosis requires extensive rearrangement of cellular architecture and of subcellular structures so that replicated chromosomes can bind correctly to spindle microtubules and segregate towards opposite poles. This process originates two new daughter nuclei with equal genetic content and relies on highly-dynamic and tightly regulated phosphorylation of numerous cell cycle proteins. A burst in protein phosphorylation orchestrated by several conserved kinases occurs as cells go into and progress through mitosis. The opposing dephosphorylation events are catalyzed by a small set of protein phosphatases, whose importance for the accuracy of mitosis is becoming increasingly appreciated. This review will focus on the established and emerging roles of mitotic phosphatases, describe their structural and biochemical properties, and discuss recent advances in understanding the regulation of phosphatase activity and function.
Collapse
Affiliation(s)
- Margarida Moura
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
- Programa Doutoral em Biologia Molecular e Celular (MCbiology), Instituto de Ciências Biomédicas Abel Salazar (ICBAS), Universidade do Porto, 4050-313 Porto, Portugal.
| | - Carlos Conde
- IBMC-Instituto de Biologia Molecular e Celular, Universidade do Porto, 4200-135 Porto, Portugal.
- i3S-Instituto de Investigação e Inovação em Saúde da Universidade do Porto, 4200-135, Porto, Portugal.
| |
Collapse
|
9
|
Yu ZH, Zhang ZY. Regulatory Mechanisms and Novel Therapeutic Targeting Strategies for Protein Tyrosine Phosphatases. Chem Rev 2018; 118:1069-1091. [PMID: 28541680 PMCID: PMC5812791 DOI: 10.1021/acs.chemrev.7b00105] [Citation(s) in RCA: 70] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
An appropriate level of protein phosphorylation on tyrosine is essential for cells to react to extracellular stimuli and maintain cellular homeostasis. Faulty operation of signal pathways mediated by protein tyrosine phosphorylation causes numerous human diseases, which presents enormous opportunities for therapeutic intervention. While the importance of protein tyrosine kinases in orchestrating the tyrosine phosphorylation networks and in target-based drug discovery has long been recognized, the significance of protein tyrosine phosphatases (PTPs) in cellular signaling and disease biology has historically been underappreciated, due to a large extent to an erroneous assumption that they are largely constitutive and housekeeping enzymes. Here, we provide a comprehensive examination of a number of regulatory mechanisms, including redox modulation, allosteric regulation, and protein oligomerization, that control PTP activity. These regulatory mechanisms are integral to the myriad PTP-mediated biochemical events and reinforce the concept that PTPs are indispensable and specific modulators of cellular signaling. We also discuss how disruption of these PTP regulatory mechanisms can cause human diseases and how these diverse regulatory mechanisms can be exploited for novel therapeutic development.
Collapse
Affiliation(s)
- Zhi-Hong Yu
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
| | - Zhong-Yin Zhang
- Department of Medicinal Chemistry and Molecular Pharmacology, Department of Chemistry, Center for Cancer Research, and Institute for Drug Discovery, Purdue University, 720 Clinic Drive, West Lafayette, IN 47907
| |
Collapse
|
10
|
Zou M, Wang J, Gao J, Han H, Fang Y. Phosphoproteomic analysis of the antitumor effects of ginsenoside Rg3 in human breast cancer cells. Oncol Lett 2017; 15:2889-2898. [PMID: 29435015 PMCID: PMC5778838 DOI: 10.3892/ol.2017.7654] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 11/10/2017] [Indexed: 12/17/2022] Open
Abstract
The incidence of breast cancer has been increasing in China and the age of breast cancer onset is earlier compared with Western countries. Compounds commonly used in Traditional Chinese Medicine (TCM) are an important source of anticancer drugs. Ginseng is one of the most common medicines used in TCM. Ginsenosides, which are saponins found in the ginseng plant, are the major active components responsible for the chemopreventive effects of ginseng in cancer. However, the mechanisms by which ginsenosides exert their anticancer effects remain elusive. The current study combined tandem mass tag (TMT)-based quantification with titanium dioxide-based phosphopeptide enrichment to quantitatively analyze the changes in phosphoproteomes in breast cancer MDA-MB-231 cells that occur following treatment with the ginsenoside Rg3. A total of 5,140 phosphorylation sites on 2,041 phosphoproteins were quantified and it was demonstrated that the phosphorylation status of 13 sites were altered in MDA-MB-231 cells following treatment with Rg3. The perturbed phosphoproteins were: Cleavage and polyadenylation specificity factor subunit 7, elongation factor 2 (EEF2), HIRA-interacting protein 3, melanoma-associated antigen D2, myosin phosphatase Rho-interacting protein, probable E3 ubiquitin-protein ligase MYCBP2, PRKC apoptosis WT1 regulator protein, protein phosphatase 1 regulatory subunit 12A, E3 SUMO-protein ligase RanBP2, Septin-9, thymopoietin, and E3 UFM1-protein ligase 1. Western blotting confirmed that Rg3 increased the phosphorylation of EEF2 on Thr57 but did not alter the protein expression of EEF2 in MDA-MB-231 and HCC1143 cells. These ginsenoside Rg3-regulated proteins are involved in various biological processes, including protein synthesis, cell division and the inhibition of nuclear factor-κB signaling. The results of the present study revealed that Rg3 exerts its anticancer effects via a combination of different signaling pathways.
Collapse
Affiliation(s)
- Mingjin Zou
- Department of Clinical Laboratory, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Jing Wang
- Department of Breast Surgical Oncology, National Cancer Center and Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, P.R. China
| | - Jidong Gao
- Department of Breast Surgical Oncology, National Cancer Center and Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, P.R. China
| | - Hui Han
- Department of Infection Control, Qilu Hospital of Shandong University, Jinan, Shandong 250012, P.R. China
| | - Yi Fang
- Department of Breast Surgical Oncology, National Cancer Center and Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing 100021, P.R. China
| |
Collapse
|
11
|
Rivera M, Ramos Y, Rodríguez-Valentín M, López-Acevedo S, Cubano LA, Zou J, Zhang Q, Wang G, Boukli NM. Targeting multiple pro-apoptotic signaling pathways with curcumin in prostate cancer cells. PLoS One 2017; 12:e0179587. [PMID: 28628644 PMCID: PMC5476315 DOI: 10.1371/journal.pone.0179587] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Accepted: 06/01/2017] [Indexed: 01/07/2023] Open
Abstract
Curcumin, an extract from the turmeric rhizome (Curcuma longa), is known to exhibit anti-inflammatory, antioxidant, chemopreventive and antitumoral activities against aggressive and recurrent cancers. Accumulative data indicate that curcumin may induce cancer cell death. However, the detailed mechanism underlying its pro-apoptotic and anti-cancer effects remains to be elucidated. In the present study, we examined the signaling pathways triggered by curcumin, specifically, the exact molecular mechanisms of curcumin-induced apoptosis in highly metastatic human prostate cancer cells. The effect of curcumin was evaluated using for the first time in prostate cancer, a gel-free shotgun quantitative proteomic analysis coupled with Tandem Mass Tag isobaric labeling-based-signaling networks. Results were confirmed at the gene expression level by qRT-PCR and at the protein expression level by western blot and flow cytometry. Our findings revealed that curcumin induced an Endoplasmic Reticulum stress-mediated apoptosis in PC3. The mechanisms by which curcumin promoted cell death in these cells were associated with cell cycle arrest, increased reactive oxygen species, autophagy and the Unfolded Protein Response. Furthermore, the upregulation of ER stress was measured using key indicators of ER stress: Glucose-Regulated Protein 78, Inositol-Requiring Enzyme 1 alpha, Protein Disulfide isomerase and Calreticulin. Chronic ER stress induction was concomitant with the upregulation of pro-apoptotic markers (caspases 3,9,12) and Poly (ADP-ribose) polymerase. The downregulated proteins include anti-apoptotic and anti-tumor markers, supporting their curcumin-induced pro-apoptotic role in prostate cancer cells. Taken together, these data suggest that curcumin may serve as a promising anticancer agent by inducing a chronic ER stress mediated cell death and activation of cell cycle arrest, UPR, autophagy and oxidative stress responses.
Collapse
Affiliation(s)
- Mariela Rivera
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| | - Yanilda Ramos
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| | - Madeline Rodríguez-Valentín
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| | - Sheila López-Acevedo
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| | - Luis A. Cubano
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| | - Jin Zou
- Center for Cancer Research and Therapeutic Development, Clark Atlanta University, Atlanta, Georgia, United States of America
| | - Qiang Zhang
- Department of Chemistry, RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Guangdi Wang
- Department of Chemistry, RCMI Cancer Research Center, Xavier University of Louisiana, New Orleans, Louisiana, United States of America
| | - Nawal M. Boukli
- Department of Microbiology and Immunology, Biomedical Proteomics Facility, Universidad Central del Caribe School of Medicine, Bayamón, Puerto Rico, United States of America
| |
Collapse
|
12
|
Kim HS, Fernandes G, Lee CW. Protein Phosphatases Involved in Regulating Mitosis: Facts and Hypotheses. Mol Cells 2016; 39:654-62. [PMID: 27669825 PMCID: PMC5050529 DOI: 10.14348/molcells.2016.0214] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Revised: 09/19/2016] [Accepted: 09/19/2016] [Indexed: 12/19/2022] Open
Abstract
Almost all eukaryotic proteins are subject to post-translational modifications during mitosis and cell cycle, and in particular, reversible phosphorylation being a key event. The recent use of high-throughput experimental analyses has revealed that more than 70% of all eukaryotic proteins are regulated by phosphorylation; however, the mechanism of dephosphorylation, counteracting phosphorylation, is relatively unknown. Recent discoveries have shown that many of the protein phosphatases are involved in the temporal and spatial control of mitotic events, such as mitotic entry, mitotic spindle assembly, chromosome architecture changes and cohesion, and mitotic exit. This implies that certain phosphatases are tightly regulated for timely dephosphorylation of key mitotic phosphoproteins and are essential for control of various mitotic processes. This review describes the physiological and pathological roles of mitotic phosphatases, as well as the versatile role of various protein phosphatases in several mitotic events.
Collapse
Affiliation(s)
- Hyun-Soo Kim
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419,
Korea
| | - Gary Fernandes
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419,
Korea
| | - Chang-Woo Lee
- Department of Molecular Cell Biology, Sungkyunkwan University School of Medicine, Suwon 16419,
Korea
- Department of Health Sciences and Technology, SAIHST, Sungkyunkwan University, Seoul 06351,
Korea
| |
Collapse
|
13
|
Delmaghani S, Aghaie A, Bouyacoub Y, El Hachmi H, Bonnet C, Riahi Z, Chardenoux S, Perfettini I, Hardelin JP, Houmeida A, Herbomel P, Petit C. Mutations in CDC14A, Encoding a Protein Phosphatase Involved in Hair Cell Ciliogenesis, Cause Autosomal-Recessive Severe to Profound Deafness. Am J Hum Genet 2016; 98:1266-1270. [PMID: 27259055 DOI: 10.1016/j.ajhg.2016.04.015] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/27/2016] [Indexed: 12/30/2022] Open
Abstract
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.
Collapse
Affiliation(s)
- Sedigheh Delmaghani
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France; UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France
| | - Asadollah Aghaie
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France; Syndrome de Usher et Autres Atteintes Rétino-Cochléaires, Institut de la Vision, 75012 Paris, France
| | - Yosra Bouyacoub
- Institut Pasteur de Tunis, LR11IPT05, Biomedical Genomics and Oncogenetics Laboratory, Tunis 1002, Tunisia; Université de Monastir, Institut Supérieur de Biotechnologie, BP 56 Monastir 5000, Tunisia
| | - Hala El Hachmi
- Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences et Techniques, Nouakchott 5026, Mauritania
| | - Crystel Bonnet
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France; Syndrome de Usher et Autres Atteintes Rétino-Cochléaires, Institut de la Vision, 75012 Paris, France
| | - Zied Riahi
- UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France; Syndrome de Usher et Autres Atteintes Rétino-Cochléaires, Institut de la Vision, 75012 Paris, France
| | - Sebastien Chardenoux
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France; UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France
| | - Isabelle Perfettini
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France; UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France
| | - Jean-Pierre Hardelin
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France; UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France
| | - Ahmed Houmeida
- Laboratoire de Biochimie et Biologie Moléculaire, Faculté des Sciences et Techniques, Nouakchott 5026, Mauritania
| | - Philippe Herbomel
- Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France; Unité des Macrophages et Développement de l'Immunité, Institut Pasteur, 75015 Paris, France; UMR 3738, Centre National de la Recherche Scientifique, 75015 Paris, France
| | - Christine Petit
- Unité de Génétique et Physiologie de l'Audition, Institut Pasteur, 75015 Paris, France; UMRS 1120, Institut National de la Santé et de la Recherche Médicale, 75015 Paris, France; Sorbonne Universités, Université Pierre et Marie Curie, Complexité du Vivant, 75005 Paris, France; Syndrome de Usher et Autres Atteintes Rétino-Cochléaires, Institut de la Vision, 75012 Paris, France; Collège de France, 75005 Paris, France.
| |
Collapse
|
14
|
Closing a gap in the nuclear envelope. Curr Opin Cell Biol 2016; 40:90-97. [PMID: 27016712 DOI: 10.1016/j.ceb.2016.03.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 02/13/2016] [Accepted: 03/05/2016] [Indexed: 11/22/2022]
Abstract
The nuclear envelope (NE) ensures nucleo-cytoplasmic compartmentalization, with trafficking of macromolecules across this double membrane controlled by embedded nuclear pore complexes (NPCs). The NE and associated proteins are dismantled during open mitosis and reestablishment of this barrier during mitotic exit requires dynamic remodeling of endoplasmic reticulum (ER) membranes and coordination with NPC reformation, with NPC deposition continuing during subsequent interphase. In this review, we discuss recent progress in our understanding of NE reformation and nuclear pore complex generation, with special focus on work implicating the endosomal sorting complex required for transport (ESCRT) membrane remodeling machinery in these events.
Collapse
|
15
|
Powers BL, Melesse M, Eissler CL, Charbonneau H, Hall MC. Measuring Activity and Specificity of Protein Phosphatases. Methods Mol Biol 2016; 1342:221-235. [PMID: 26254927 DOI: 10.1007/978-1-4939-2957-3_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Reversible protein phosphorylation plays essential roles in coordinating cell division and many other biological processes. Cell cycle regulation by opposing kinase and protein phosphatase activities is often complex and major challenges exist in identifying the direct substrates of these enzymes and the specific sites at which they act. While cell cycle kinases are known to exhibit strict substrate specificities important for coordinating the complex events of cell division, phosphatases have only recently been recognized to exert similarly precise regulatory control over cell cycle events through timely dephosphorylation of specific substrates. The molecular determinants for substrate recognition by many phosphatases that function in cell division are still poorly delineated. To understand phosphatase specificity, it is critical to employ methods that monitor the dephosphorylation of individual phosphorylation sites on physiologically relevant substrates. Here, using the cell cycle phosphatase Cdc14 as an example, we describe two methods for studying phosphatase specificity, one using synthetic phosphopeptide substrates and the other using intact phosphoprotein substrates. These methods are useful for targeted characterization of small substrate sets and are also adaptable to large-scale applications for global specificity studies.
Collapse
Affiliation(s)
- Brendan L Powers
- Department of Biochemistry and Center for Cancer Research, Purdue University, West Lafayette, IN, 47907, USA
| | | | | | | | | |
Collapse
|
16
|
Rebelo S, Santos M, Martins F, da Cruz e Silva EF, da Cruz e Silva OA. Protein phosphatase 1 is a key player in nuclear events. Cell Signal 2015; 27:2589-98. [DOI: 10.1016/j.cellsig.2015.08.007] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Revised: 07/31/2015] [Accepted: 08/10/2015] [Indexed: 12/17/2022]
|
17
|
Rusin SF, Schlosser KA, Adamo ME, Kettenbach AN. Quantitative phosphoproteomics reveals new roles for the protein phosphatase PP6 in mitotic cells. Sci Signal 2015; 8:rs12. [PMID: 26462736 DOI: 10.1126/scisignal.aab3138] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
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.
Collapse
Affiliation(s)
- Scott F Rusin
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA
| | - Kate A Schlosser
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Mark E Adamo
- Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA
| | - Arminja N Kettenbach
- Department of Biochemistry, Geisel School of Medicine at Dartmouth, Hanover, NH 03755, USA. Norris Cotton Cancer Center, Geisel School of Medicine at Dartmouth, Lebanon, NH 03756, USA.
| |
Collapse
|
18
|
Pandey R, Mohmmed A, Pierrot C, Khalife J, Malhotra P, Gupta D. Genome wide in silico analysis of Plasmodium falciparum phosphatome. BMC Genomics 2014; 15:1024. [PMID: 25425018 PMCID: PMC4256932 DOI: 10.1186/1471-2164-15-1024] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2014] [Accepted: 11/12/2014] [Indexed: 01/18/2023] Open
Abstract
BACKGROUND Eukaryotic cellular machineries are intricately regulated by several molecular mechanisms involving transcriptional control, post-translational control and post-translational modifications of proteins (PTMs). Reversible protein phosphorylation/dephosphorylation process, which involves kinases as well as phosphatases, represents an important regulatory mechanism for diverse pathways and systems in all organisms including human malaria parasite, Plasmodium falciparum. Earlier analysis on P. falciparum protein-phosphatome revealed presence of 34 phosphatases in Plasmodium genome. Recently, we re-analysed P. falciparum phosphatome aimed at identifying parasite specific phosphatases. RESULTS Plasmodium database (PlasmoDB 9.2) search, combined with PFAM and CDD searches, revealed 67 candidate phosphatases in P. falciparum. While this number is far less than the number of phosphatases present in Homo sapiens, it is almost the same as in other Plasmodium species. These Plasmodium phosphatase proteins were classified into 13 super families based on NCBI CDD search. Analysis of proteins expression profiles of the 67 phosphatases revealed that 44 phosphatases are expressed in both schizont as well as gametocytes stages. Fourteen phosphatases are common in schizont, ring and trophozoite stages, four phosphatases are restricted to gametocytes, whereas another three restricted to schizont stage. The phylogenetic trees for each of the known phosphatase super families reveal a considerable phylogenetic closeness amongst apicomplexan organisms and a considerable phylogenetic distance with other eukaryotic model organisms included in the study. The GO assignments and predicted interaction partners of the parasite phosphatases indicate its important role in diverse cellular processes. CONCLUSION In the study presented here, we reviewed the P. falciparum phosphatome to show presence of 67 candidate phosphatases in P. falciparum genomes/proteomes. Intriguingly, amongst these phosphatases, we could identify six Plasmodium specific phosphatases and 33 putative phosphatases that do not have human orthologs, thereby suggesting that these phosphatases have the potential to be explored as novel antimalarial drug targets.
Collapse
Affiliation(s)
| | | | | | - Jamal Khalife
- Structural and Computational Biology group, International Centre for Genetic Engineering and Biotechnology, Aruna Asaf Ali Marg, New Delhi 110067, India.
| | | | | |
Collapse
|
19
|
Eiteneuer A, Seiler J, Weith M, Beullens M, Lesage B, Krenn V, Musacchio A, Bollen M, Meyer H. Inhibitor-3 ensures bipolar mitotic spindle attachment by limiting association of SDS22 with kinetochore-bound protein phosphatase-1. EMBO J 2014; 33:2704-20. [PMID: 25298395 DOI: 10.15252/embj.201489054] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
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). Depletion of I3 does not affect the amount of PP1 at kinetochores but causes quantitative association of SDS22 with PP1 on KNL1 at the kinetochore. Such accumulation of SDS22 at kinetochores interferes with PP1 activity and inhibits Aurora B threonine-232 dephosphorylation, which leads to increased Aurora B activity in metaphase and persistence in anaphase accompanied with segregation defects. We propose a model in which I3 regulates an SDS22-mediated PP1 activation step in solution that precedes SDS22 dissociation and transfer of PP1 to kinetochores, and which is required for PP1 to efficiently antagonize Aurora B.
Collapse
Affiliation(s)
- Annika Eiteneuer
- Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Jonas Seiler
- Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Matthias Weith
- Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| | - Monique Beullens
- Laboratory of Biosignaling & Therapeutics, KU Leuven, Department of Cellular and Molecular Medicine, University of Leuven, Leuven, Belgium
| | - Bart Lesage
- Laboratory of Biosignaling & Therapeutics, KU Leuven, Department of Cellular and Molecular Medicine, University of Leuven, Leuven, Belgium
| | - Veronica Krenn
- Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Andrea Musacchio
- Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany Department of Mechanistic Cell Biology, Max Planck Institute of Molecular Physiology, Dortmund, Germany
| | - Mathieu Bollen
- Laboratory of Biosignaling & Therapeutics, KU Leuven, Department of Cellular and Molecular Medicine, University of Leuven, Leuven, Belgium
| | - Hemmo Meyer
- Centre for Medical Biotechnology, Faculty of Biology, University of Duisburg-Essen, Essen, Germany
| |
Collapse
|
20
|
Cui C, Ren X, Liu D, Deng X, Qin X, Zhao X, Wang E, Yu B. 14-3-3 epsilon prevents G2/M transition of fertilized mouse eggs by binding with CDC25B. BMC DEVELOPMENTAL BIOLOGY 2014; 14:33. [PMID: 25059436 PMCID: PMC4222595 DOI: 10.1186/s12861-014-0033-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/27/2014] [Accepted: 07/14/2014] [Indexed: 12/21/2022]
Abstract
Background The 14-3-3 (YWHA) proteins are highly conserved in higher eukaryotes, participate in various cellular signaling pathways including cell cycle regulation, development and growth. Our previous studies demonstrated that 14-3-3ε (YWHAE) is responsible for maintaining prophase | arrest in mouse oocyte. However, roles of 14-3-3ε in the mitosis of fertilized mouse eggs have remained unclear. Here, we showed that 14-3-3ε interacts and cooperates with CDC25B phosphorylated at Ser321 regulating G2/M transition of mitotic progress of fertilized mouse eggs. Results Disruption of 14-3-3ε expression by RNAi prevented normal G2/M transition by inhibition of MPF activity and leaded to the translocation of CDC25B into the nucleus from the cytoplasm. Overexpression of 14-3-3ε-WT and unphosphorylatable CDC25B mutant (CDC25B-S321A) induced mitotic resumption in dbcAMP-arrested eggs. In addition, we examined endogenous and exogenous distribution of 14-3-3ε and CDC25B. Endogenous 14-3-3ε and CDC25B were co-localized primarily in the cytoplasm at the G1, S, early G2 and M phases whereas CDC25B was found to accumulate in the nucleus at the late G2 phase. Upon coexpression with RFP–14-3-3ε, GFP–CDC25B–WT and GFP–CDC25B–S321A were predominantly cytoplasmic at early G2 phase and then GFP–CDC25B–S321A moved to the nucleus whereas CDC25B-WT signals were observed in the cytoplasm without nucleus accumulation at late G2 phase at presence of dbcAMP. Conclusions Our data indicate that 14-3-3ε is required for the mitotic entry in the fertilized mouse eggs. 14-3-3ε is primarily responsible for sequestering the CDC25B in cytoplasm and 14-3-3ε binding to CDC25B-S321 phosphorylated by PKA induces mitotic arrest at one-cell stage by inactivation of MPF in fertilized mouse eggs.
Collapse
|
21
|
DeVaul N, Wang R, Sperry AO. PPP1R42, a PP1 binding protein, regulates centrosome dynamics in ARPE-19 cells. Biol Cell 2013; 105:359-71. [PMID: 23718219 DOI: 10.1111/boc.201300019] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Accepted: 05/24/2013] [Indexed: 12/20/2022]
Abstract
BACKGROUND The centrosome is the primary site for microtubule nucleation in cells and orchestrates reorganisation of the microtubule cytoskeleton during the cell cycle. The activities of the centrosome must be closely aligned with progression of the cell cycle; misregulation of centrosome separation and duplication is a hallmark of cancer. In a subset of cells, including the developing spermatid, the centrosome becomes specialised to form the basal body thereby supporting growth of the axoneme in morphogenesis of cilia and flagella, structures critical for signalling and motility. Mammalian spermatogenesis is an excellent model system to investigate the transformations in cellular architecture that accompany these changes including formation of the flagellum. We have previously identified a leucine-rich repeat protein (PPP1R42) that contains a protein phosphatase-1 binding site and translocates from the apical nucleus to the centrosome at the base of the flagellum during spermiogenesis. In this manuscript, we examine localisation and function of PPP1R42 in a ciliated epithelial cell model as a first step in understanding the role of this protein in centrosome function and flagellar formation. RESULTS We demonstrate that PPP1R42 localises to the basal body in ARPE-19 retinal epithelial cells. Co-localisation and co-immunoprecipitation experiments further show that PPP1R42 interacts with γ-tubulin. Inhibition of PPP1R42 with small interfering RNAs causes accumulation of centrosomes indicating premature centrosome separation. Importantly, the activity of two signalling molecules that regulate centrosome separation, PP1 phosphatase and NEK2 kinase, changes when PPP1R42 is inhibited: PP1 activity is reduced with a corresponding increase in NEK2 activity. CONCLUSIONS We have identified a role for the PP1-binding protein, PPP1R42, in centrosome separation in ciliated ARPE-19 cells. Our finding that inhibition of PPP1R42 expression increases the number of centrosomes per cell is consistent with our model that PPP1R42 is a positive regulator of PP1. PPP1R42 depletion reduces the activity of PP1 leading to activation of NEK2, the kinase responsible for phosphorylation of centrosomal linker proteins promoting centrosome separation. This work identifies a new molecule localised to the centrosome and basal body with a role in the complex signalling network responsible for controlling centrosome activities.
Collapse
Affiliation(s)
- Nicole DeVaul
- Department of Anatomy and Cell Biology, East Carolina University, Brody School of Medicine, Greenville, NC, USA
| | | | | |
Collapse
|
22
|
Abstract
To maintain cellular homeostasis against the demands of the extracellular environment, a precise regulation of kinases and phosphatases is essential. In cell cycle regulation mechanisms, activation of the cyclin-dependent kinase (CDK1) and cyclin B complex (CDK1:cyclin B) causes a remarkable change in protein phosphorylation. Activation of CDK1:cyclin B is regulated by two auto-amplification loops-CDK1:cyclin B activates Cdc25, its own activating phosphatase, and inhibits Wee1, its own inhibiting kinase. Recent biological evidence has revealed that the inhibition of its counteracting phosphatase activity also occurs, and it is parallel to CDK1:cyclin B activation during mitosis. Phosphatase regulation of mitotic kinases and their substrates is essential to ensure that the progression of the cell cycle is ordered. Outlining how the mutual control of kinases and phosphatases governs the localization and timing of cell division will give us a new understanding about cell cycle regulation.
Collapse
Affiliation(s)
| | - Young Yang
- Center for Women’s Disease, Department of Biological Science, Sookmyung Women’s University, Seoul 140-742, Korea
| |
Collapse
|
23
|
Chen JS, Broadus MR, McLean JR, Feoktistova A, Ren L, Gould KL. Comprehensive proteomics analysis reveals new substrates and regulators of the fission yeast clp1/cdc14 phosphatase. Mol Cell Proteomics 2013; 12:1074-86. [PMID: 23297348 DOI: 10.1074/mcp.m112.025924] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
The conserved family of Cdc14 phosphatases targets cyclin-dependent kinase substrates in yeast, mediating late mitotic signaling events. To discover substrates and regulators of the Schizosaccharomyces pombe Cdc14 phosphatase Clp1, TAP-tagged Clp1, and a substrate trapping mutant (Clp1-C286S) were purified from asynchronous and mitotic (prometaphase and anaphase) cells and binding partners were identified by 2D-LC-MS/MS. Over 100 Clp1-interacting proteins were consistently identified, over 70 of these were enriched in Clp1-C286S-TAP (potential substrates) and we and others detected Cdk1 phosphorylation sites in over half (44/73) of these potential substrates. According to GO annotations, Clp1-interacting proteins are involved in many essential cellular processes including mitosis, cytokinesis, ribosome biogenesis, transcription, and trafficking among others. We confirmed association and dephosphorylation of multiple candidate substrates, including a key scaffolding component of the septation initiation network called Cdc11, an essential kinase of the conserved morphogenesis-related NDR kinase network named Shk1, and multiple Mlu1-binding factor transcriptional regulators. In addition, we identified Sal3, a nuclear β-importin, as the sole karyopherin required for Clp1 nucleoplasmic shuttling, a key mode of Cdc14 phosphatase regulation. Finally, a handful of proteins were more abundant in wild type Clp1-TAP versus Clp1-C286S-TAP, suggesting that they may directly regulate Clp1 signaling or serve as scaffolding platforms to localize Clp1 activity.
Collapse
Affiliation(s)
- Jun-Song Chen
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, 1161 21 Avenue South, MCN B2309, Nashville, Tennessee 37232, USA
| | | | | | | | | | | |
Collapse
|
24
|
Mathematical modeling of fission yeast Schizosaccharomyces pombe cell cycle: exploring the role of multiple phosphatases. SYSTEMS AND SYNTHETIC BIOLOGY 2012. [PMID: 23205155 DOI: 10.1007/s11693-011-9090-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
UNLABELLED Cell cycle is the central process that regulates growth and division in all eukaryotes. Based on the environmental condition sensed, the cell lies in a resting phase G0 or proceeds through the cyclic cell division process (G1→S→G2→M). These series of events and phase transitions are governed mainly by the highly conserved Cyclin dependent kinases (Cdks) and its positive and negative regulators. The cell cycle regulation of fission yeast Schizosaccharomyces pombe is modeled in this study. The study exploits a detailed molecular interaction map compiled based on the published model and experimental data. There are accumulating evidences about the prominent regulatory role of specific phosphatases in cell cycle regulations. The current study emphasizes the possible role of multiple phosphatases that governs the cell cycle regulation in fission yeast S. pombe. The ability of the model to reproduce the reported regulatory profile for the wild-type and various mutants was verified though simulations. ELECTRONIC SUPPLEMENTARY MATERIAL The online version of this article (doi:10.1007/s11693-011-9090-7) contains supplementary material, which is available to authorized users.
Collapse
|
25
|
Jarboui MA, Bidoia C, Woods E, Roe B, Wynne K, Elia G, Hall WW, Gautier VW. Nucleolar protein trafficking in response to HIV-1 Tat: rewiring the nucleolus. PLoS One 2012; 7:e48702. [PMID: 23166591 PMCID: PMC3499507 DOI: 10.1371/journal.pone.0048702] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2012] [Accepted: 10/03/2012] [Indexed: 12/20/2022] Open
Abstract
The trans-activator Tat protein is a viral regulatory protein essential for HIV-1 replication. Tat trafficks to the nucleoplasm and the nucleolus. The nucleolus, a highly dynamic and structured membrane-less sub-nuclear compartment, is the site of rRNA and ribosome biogenesis and is involved in numerous cellular functions including transcriptional regulation, cell cycle control and viral infection. Importantly, transient nucleolar trafficking of both Tat and HIV-1 viral transcripts are critical in HIV-1 replication, however, the role(s) of the nucleolus in HIV-1 replication remains unclear. To better understand how the interaction of Tat with the nucleolar machinery contributes to HIV-1 pathogenesis, we investigated the quantitative changes in the composition of the nucleolar proteome of Jurkat T-cells stably expressing HIV-1 Tat fused to a TAP tag. Using an organellar proteomic approach based on mass spectrometry, coupled with Stable Isotope Labelling in Cell culture (SILAC), we quantified 520 proteins, including 49 proteins showing significant changes in abundance in Jurkat T-cell nucleolus upon Tat expression. Numerous proteins exhibiting a fold change were well characterised Tat interactors and/or known to be critical for HIV-1 replication. This suggests that the spatial control and subcellular compartimentaliation of these cellular cofactors by Tat provide an additional layer of control for regulating cellular machinery involved in HIV-1 pathogenesis. Pathway analysis and network reconstruction revealed that Tat expression specifically resulted in the nucleolar enrichment of proteins collectively participating in ribosomal biogenesis, protein homeostasis, metabolic pathways including glycolytic, pentose phosphate, nucleotides and amino acids biosynthetic pathways, stress response, T-cell signaling pathways and genome integrity. We present here the first differential profiling of the nucleolar proteome of T-cells expressing HIV-1 Tat. We discuss how these proteins collectively participate in interconnected networks converging to adapt the nucleolus dynamic activities, which favor host biosynthetic activities and may contribute to create a cellular environment supporting robust HIV-1 production.
Collapse
Affiliation(s)
- Mohamed Ali Jarboui
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Carlo Bidoia
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Elena Woods
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Barbara Roe
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Kieran Wynne
- Mass Spectrometry Resource (MSR), Conway Institute for Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - Giuliano Elia
- Mass Spectrometry Resource (MSR), Conway Institute for Biomolecular and Biomedical Research, University College Dublin (UCD), Dublin, Ireland
| | - William W. Hall
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| | - Virginie W. Gautier
- Centre for Research in Infectious Diseases (CRID), School of Medicine and Medical Science (SMMS), University College Dublin (UCD), Dublin, Ireland
| |
Collapse
|
26
|
Marquina M, Queralt E, Casamayor A, Ariño J. Lack of the Glc7 phosphatase regulatory subunit Ypi1 activates the morphogenetic checkpoint. Int J Biochem Cell Biol 2012; 44:1862-71. [DOI: 10.1016/j.biocel.2012.06.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 06/15/2012] [Accepted: 06/19/2012] [Indexed: 10/28/2022]
|
27
|
Clément A, Solnica-Krezel L, Gould KL. Functional redundancy between Cdc14 phosphatases in zebrafish ciliogenesis. Dev Dyn 2012; 241:1911-21. [PMID: 23027426 PMCID: PMC3508521 DOI: 10.1002/dvdy.23876] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/20/2012] [Indexed: 01/20/2023] Open
Abstract
BACKGROUND Cyclin-dependent kinases (Cdks) and their counteracting phosphatases are key regulators of cell cycle progression. In yeasts, the Cdc14 family of phosphatases promotes exit from mitosis and progression through cytokinesis by reversing phosphorylation of Cdk1 substrates. In vertebrates, CDC14 paralogs, CDC14A and CDC14B, have so far been implicated in processes ranging from DNA damage repair, meiosis, centrosome duplication to ciliogenesis. However, the question of whether CDC14 paralogs can functionally compensate for each other has yet to be addressed. RESULTS Here, using antisense morpholino oligonucleotides to inhibit Cdc14A1 function, we observed that Cdc14A1 depleted zebrafish embryos displayed ventrally curved body and left-right asymmetry defects, similar to Cdc14B deficient embryos and zebrafish mutants with cilia defects. Accordingly, we found that Cdc14A1, like Cdc14B, plays a role in ciliogenesis in the Kupffer's vesicle (KV) and other ciliated tissues, and can do so independently of its function in cell cycle. Furthermore, we observed reciprocal suppression of KV cilia length defects of Cdc14A1 and Cdc14B deficient embryos by cdc14b and cdc14a1 RNAs, respectively. CONCLUSIONS Together, these studies demonstrate for the first time that Cdc14A and Cdc14B have overlapping functions in the ciliogenesis process during zebrafish development.
Collapse
Affiliation(s)
- Aurélie Clément
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA
| | | | | |
Collapse
|
28
|
Beyer D, Tándor I, Kónya Z, Bátori R, Roszik J, Vereb G, Erdődi F, Vasas G, M-Hamvas M, Jambrovics K, Máthé C. Microcystin-LR, a protein phosphatase inhibitor, induces alterations in mitotic chromatin and microtubule organization leading to the formation of micronuclei in Vicia faba. ANNALS OF BOTANY 2012; 110:797-808. [PMID: 22819947 PMCID: PMC3423812 DOI: 10.1093/aob/mcs154] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2012] [Accepted: 05/03/2012] [Indexed: 05/31/2023]
Abstract
BACKGROUND AND AIMS Microcystin-LR (MCY-LR) is a cyanobacterial toxin, a specific inhibitor of type 1 and 2A protein phosphatases (PP1 and PP2A) with significant impact on aquatic ecosystems. It has the potential to alter regulation of the plant cell cycle. The aim of this study was improved understanding of the mitotic alterations induced by cyanotoxin in Vicia faba, a model organism for plant cell biology studies. METHODS Vicia faba seedlings were treated over the long and short term with MCY-LR purified in our laboratory. Short-term treatments were performed on root meristems synchronized with hydroxylurea. Sections of lateral root tips were labelled for chromatin, phosphorylated histone H3 and β-tubulin via histochemical and immunohistochemical methods. Mitotic activity and the occurrence of mitotic alterations were detected and analysed by fluorescence microscopy. The phosphorylation state of histone H3 was studied by Western blotting. KEY RESULTS Long-term MCY-LR exposure of lateral root tip meristems increased the percentage of either early or late mitosis in a concentration-dependent manner. We observed hypercondensed chromosomes and altered sister chromatid segregation (lagging chromosomes) leading to the formation of micronuclei, accompanied by the formation of disrupted, multipolar and monopolar spindles, disrupted phragmoplasts and the hyperphosphorylation of histone H3 at Ser10. Short-term MCY-LR treatment of synchronized cells showed that PP1 and PP2A inhibition delayed the onset of anaphase at 1 µg mL(-1) MCY-LR, accelerated cell cycle at 10 µg mL(-1) MCY-LR and induced the formation of lagging chromosomes. In this case mitotic microtubule alterations were not detected, but histone H3 was hyperphosphorylated. CONCLUSIONS MCY-LR delayed metaphase-anaphase transition. Consequently, it induced aberrant chromatid segregation and micronucleus formation that could be associated with both H3 hyperphosphorylation and altered microtubule organization. However, these two phenomena seemed to be independent. The toxin may be a useful tool in the study of plant cell cycle regulation.
Collapse
Affiliation(s)
- Dániel Beyer
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
- University of Debrecen, Medical and Health Science Centre, Department of Biophysics and Cell Biology, H-4032, Debrecen, Hungary
| | - Ildikó Tándor
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
| | - Zoltán Kónya
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
- University of Debrecen, Medical and Health Science Centre, Department of Medical Chemistry, H-4012 Debrecen, Hungary
| | - Róbert Bátori
- University of Debrecen, Medical and Health Science Centre, Department of Medical Chemistry, H-4012 Debrecen, Hungary
| | - Janos Roszik
- University of Debrecen, Medical and Health Science Centre, Department of Biophysics and Cell Biology, H-4032, Debrecen, Hungary
| | - György Vereb
- University of Debrecen, Medical and Health Science Centre, Department of Biophysics and Cell Biology, H-4032, Debrecen, Hungary
| | - Ferenc Erdődi
- University of Debrecen, Medical and Health Science Centre, Department of Medical Chemistry, H-4012 Debrecen, Hungary
| | - Gábor Vasas
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
| | - Márta M-Hamvas
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
| | - Károly Jambrovics
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
| | - Csaba Máthé
- University of Debrecen, Faculty of Science and Technology, Department of Botany, PO Box 14, H-4010, Debrecen, Hungary
| |
Collapse
|
29
|
Hyodo T, Ito S, Hasegawa H, Asano E, Maeda M, Urano T, Takahashi M, Hamaguchi M, Senga T. Misshapen-like kinase 1 (MINK1) is a novel component of striatin-interacting phosphatase and kinase (STRIPAK) and is required for the completion of cytokinesis. J Biol Chem 2012; 287:25019-29. [PMID: 22665485 DOI: 10.1074/jbc.m112.372342] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Cytokinesis is initiated by constriction of the cleavage furrow and terminated by abscission of the intercellular bridge that connects two separating daughter cells. The complicated processes of cytokinesis are coordinated by phosphorylation and dephosphorylation mediated by protein kinases and phosphatases. Mammalian Misshapen-like kinase 1 (MINK1) is a member of the germinal center kinases and is known to regulate cytoskeletal organization and oncogene-induced cell senescence. To search for novel regulators of cytokinesis, we performed a screen using a library of siRNAs and found that MINK1 was essential for cytokinesis. Time-lapse analysis revealed that MINK1-depleted cells were able to initiate furrowing but that abscission was disrupted. STRN4 (Zinedin) is a regulatory subunit of protein phosphatase 2A (PP2A) and was recently shown to be a component of a novel protein complex called striatin-interacting phosphatase and kinase (STRIPAK). Mass spectrometry analysis showed that MINK1 was a component of STRIPAK and that MINK1 directly interacted with STRN4. Similar to MINK1 depletion, STRN4-knockdown induced multinucleated cells and inhibited the completion of abscission. In addition, STRN4 reduced MINK1 activity in the presence of catalytic and structural subunits of PP2A. Our study identifies a novel regulatory network of protein kinases and phosphatases that regulate the completion of abscission.
Collapse
Affiliation(s)
- Toshinori Hyodo
- Division of Cancer Biology, Nagoya University Graduate School of Medicine, Nagoya 466-8550, Japan
| | | | | | | | | | | | | | | | | |
Collapse
|
30
|
Hernandez-Verdun D. Assembly and disassembly of the nucleolus during the cell cycle. Nucleus 2012; 2:189-94. [PMID: 21818412 DOI: 10.4161/nucl.2.3.16246] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2011] [Revised: 04/28/2011] [Accepted: 05/02/2011] [Indexed: 01/01/2023] Open
Abstract
The nucleolus is a large nuclear domain in which transcription, maturation and assembly of ribosomes take place. In higher eukaryotes, nucleolar organization in three sub-domains reflects the compartmentation of the machineries related to active or inactive transcription of the ribosomal DNA, ribosomal RNA processing and assembly with ribosomal proteins of the two (40S and 60S) ribosomal subunits. The assembly of the nucleoli during telophase/early G(1) depends on pre-existing machineries inactivated during prophase (the transcription machinery and RNP processing complexes) and on partially processed 45S rRNAs inherited throughout mitosis. In telophase, the 45S rRNAs nucleate the prenucleolar bodies and order the dynamics of nucleolar assembly. The assembly/disassembly processes of the nucleolus depend on the equilibrium between phosphorylation/dephosphorylation of the transcription machinery and on the RNP processing complexes under the control of the CDK1-cyclin B kinase and PP1 phosphatases. The dynamics of assembly/disassembly of the nucleolus is time and space regulated.
Collapse
|
31
|
Cougot D, Allemand E, Riviere L, Benhenda S, Duroure K, Levillayer F, Muchardt C, Buendia MA, Neuveut C. Inhibition of PP1 Phosphatase Activity by HBx: A Mechanism for the Activation of Hepatitis B Virus Transcription. Sci Signal 2012; 5:ra1. [DOI: 10.1126/scisignal.2001906] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
|
32
|
Barr FA, Elliott PR, Gruneberg U. Protein phosphatases and the regulation of mitosis. J Cell Sci 2011; 124:2323-34. [PMID: 21709074 DOI: 10.1242/jcs.087106] [Citation(s) in RCA: 68] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Dynamic control of protein phosphorylation is necessary for the regulation of many cellular processes, including mitosis and cytokinesis. Indeed, although the central role of protein kinases is widely appreciated and intensely studied, the importance of protein phosphatases is often overlooked. Recent studies, however, have highlighted the considerable role of protein phosphatases in both the spatial and temporal control of protein kinase activity, and the modulation of substrate phosphorylation. Here, we will focus on recent advances in our understanding of phosphatase structure, and the importance of phosphatase function in the control of mitotic spindle formation, chromosome architecture and cohesion, and cell division.
Collapse
Affiliation(s)
- Francis A Barr
- University of Liverpool, Cancer Research Centre, 200 London Road, Liverpool L3 9TA, UK.
| | | | | |
Collapse
|
33
|
Smith SB, Kiss DL, Turk E, Tartakoff AM, Andrulis ED. Pronounced and extensive microtubule defects in a Saccharomyces cerevisiae DIS3 mutant. Yeast 2011; 28:755-69. [PMID: 21919057 DOI: 10.1002/yea.1899] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2011] [Revised: 06/21/2011] [Accepted: 07/10/2011] [Indexed: 11/05/2022] Open
Abstract
Subunits of the RNA processing exosome assemble into structurally distinct protein complexes that function in disparate cellular compartments and RNA metabolic pathways. Here, in a genetic, cell biological and transcriptomic analysis, we examined the role of Dis3, an essential polypeptide with endo- and 3'→5' exo-ribonuclease activity, in cell cycle progression. We present several lines of evidence that perturbation of DIS3 affects microtubule (MT) localization and structure in Saccharomyces cerevisiae. Cells with a DIS3 mutant: (a) accumulate anaphase and pre-anaphase mitotic spindles; (b) exhibit spindles that are misorientated and displaced from the bud neck; (c) harbour elongated spindle-associated astral MTs; (d) have an increased G1 astral MT length and number; and (e) are hypersensitive to MT poisons. Mutations in the core exosome genes RRP4 and MTR3 and the exosome cofactor gene MTR4, but not other exosome subunit gene mutants, also elicit MT phenotypes. RNA deep sequencing analysis (RNA-seq) shows broad changes in the levels of cell cycle- and MT-related transcripts in mutant strains. Collectively, the data presented in this study suggest an evolutionarily conserved role for Dis3 in linking RNA metabolism, MTs and cell cycle progression.
Collapse
Affiliation(s)
- Sarah B Smith
- Department of Molecular Biology and Microbiology, Case Comprehensive Cancer Center, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | | | | | | | | |
Collapse
|
34
|
PP2A-twins is antagonized by greatwall and collaborates with polo for cell cycle progression and centrosome attachment to nuclei in drosophila embryos. PLoS Genet 2011; 7:e1002227. [PMID: 21852958 PMCID: PMC3154958 DOI: 10.1371/journal.pgen.1002227] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Accepted: 05/10/2011] [Indexed: 12/13/2022] Open
Abstract
Cell division and development are regulated by networks of kinases and phosphatases. In early Drosophila embryogenesis, 13 rapid nuclear divisions take place in a syncytium, requiring fine coordination between cell cycle regulators. The Polo kinase is a conserved, crucial regulator of M-phase. We have recently reported an antagonism between Polo and Greatwall (Gwl), another mitotic kinase, in Drosophila embryos. However, the nature of the pathways linking them remained elusive. We have conducted a comprehensive screen for additional genes functioning with polo and gwl. We uncovered a strong interdependence between Polo and Protein Phosphatase 2A (PP2A) with its B-type subunit Twins (Tws). Reducing the maternal contribution of Polo and PP2A-Tws together is embryonic lethal. We found that Polo and PP2A-Tws collaborate to ensure centrosome attachment to nuclei. While a reduction in Polo activity leads to centrosome detachments observable mostly around prophase, a reduction in PP2A-Tws activity leads to centrosome detachments at mitotic exit, and a reduction in both Polo and PP2A-Tws enhances the frequency of detachments at all stages. Moreover, we show that Gwl antagonizes PP2A-Tws function in both meiosis and mitosis. Our study highlights how proper coordination of mitotic entry and exit is required during embryonic cell cycles and defines important roles for Polo and the Gwl-PP2A-Tws pathway in this process. The development and survival of all living organisms relies on the fine regulation of cell division at the molecular level. This coordination depends on kinases and phosphatases, enzymes that catalyze the addition and removal of phosphate groups on specific target proteins. The genes encoding these enzymes have been largely conserved between species during evolution. In a previous paper published in PLoS Genetics, we found an antagonism between the Polo and Greatwall mitotic kinases in the fruit fly model. In this study, we have used fly genetics to identify additional genes that function with polo and greatwall during early embryogenesis. We have found a specific form of the Protein Phosphatase 2A (PP2A-Tws) that collaborates with the Polo kinase at a stage when multiple nuclei rapidly divide in a large, single-cell early embryo. We found that Polo and PP2A-Tws are both required for the proper cohesion between nuclei and the centrosomes, which are essential structures for mitosis and embryonic development. We also found that the Greatwall kinase antagonizes the PP2A-Tws phosphatase to promote mitosis and meiosis. Our genetic study sheds new light on cell cycle regulation and is consistent with recent results from biochemical studies using frog cell extracts.
Collapse
|
35
|
Pathological modifications following sub-chronic exposure of medaka fish (Oryzias latipes) to microcystin-LR. Reprod Toxicol 2011; 32:329-40. [PMID: 21839164 DOI: 10.1016/j.reprotox.2011.07.006] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2010] [Revised: 06/15/2011] [Accepted: 07/25/2011] [Indexed: 12/29/2022]
Abstract
Microcystins (MCs) are toxic monocyclic heptapeptides produced by many cyanobacteria. MCs, especially MC-LR, cause toxic effects in animals and are a recognized potent cause of environmental stress and health hazard in aquatic ecosystems when heavy blooms of cyanobacteria appear. Consequently, one of the major problems is the chronic exposure of fish to cyanotoxins in their natural environment. The present experiment involving chronic exposure confirmed initial findings on acute exposure to MC contamination: exacerbated physiological stress and tissue damage in several tissues of exposed medaka fish. The gonads were affected specifically. In female gonads the modifications included reduction of the vitellus storage, lysis of the gonadosomatic tissue and disruption of the relationships between the follicular cells and the oocytes. In the males, spermatogenesis appeared to be disrupted. This is the first report showing that a cyanotoxin can affect reproductive function, and so can impact on fish reproduction and thus fish stocks.
Collapse
|
36
|
Wurzenberger C, Gerlich DW. Phosphatases: providing safe passage through mitotic exit. Nat Rev Mol Cell Biol 2011; 12:469-82. [PMID: 21750572 DOI: 10.1038/nrm3149] [Citation(s) in RCA: 236] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The mitosis-to-interphase transition involves dramatic cellular reorganization from a state that supports chromosome segregation to a state that complies with all functions of an interphase cell. This process, termed mitotic exit, depends on the removal of mitotic phosphorylations from a broad range of substrates. Mitotic exit regulation involves inactivation of mitotic kinases and activation of counteracting protein phosphatases. The key mitotic exit phosphatase in budding yeast, Cdc14, is now well understood. By contrast, in animal cells, it is now emerging that mitotic exit relies on distinct regulatory networks, including the protein phosphatases PP1 and PP2A.
Collapse
Affiliation(s)
- Claudia Wurzenberger
- Institute of Biochemistry, Department of Biology, Swiss Federal Institute of Technology Zürich (ETHZ), HPM D11.3, Schafmattstrasse 18, 8093 Zürich, Switzerland
| | | |
Collapse
|
37
|
Voronkov M, Braithwaite SP, Stock JB. Phosphoprotein phosphatase 2A: a novel druggable target for Alzheimer's disease. Future Med Chem 2011; 3:821-33. [PMID: 21644827 PMCID: PMC3292348 DOI: 10.4155/fmc.11.47] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Tau hyperphosphorylation is thought to play an important role in the etiology of Alzheimer's disease by facilitating the formation of neurofibrillary tangles. Reducing phosphorylation through kinase inhibition has therefore emerged as a target for drug development, but despite considerable efforts to develop therapeutic kinase inhibitors, success has been limited. An alternative approach is to develop pharmaceuticals to enhance the activity of the principal phospho-tau phosphatase, phosphoprotein phosphatase 2A (PP2A). In this article we review evidence that this mechanism is pharmacologically achievable and has promise for delivering the next generation of Alzheimer's disease therapeutics. A number of different chemotypes have been reported to lead to enhanced PP2A activity through a range of proposed mechanisms. Some of these compounds appear to act directly as allosteric activators of PP2A, while others act indirectly by inhibiting the binding of PP2A inhibitors or by altering post-translational modifications that act in turn to regulate PP2A activity towards phospho-tau. These results indicate that PP2A may provide a useful target that can be safely, selectively and effectively modulated through pharmaceutical intervention to treat Alzheimer's disease.
Collapse
Affiliation(s)
| | | | - Jeffry B Stock
- Signum Biosciences, Monmouth Junction, NJ 08852, USA
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA
| |
Collapse
|
38
|
Matsumura F, Yamakita Y, Yamashiro S. Myosin phosphatase-targeting subunit 1 controls chromatid segregation. J Biol Chem 2011; 286:10825-33. [PMID: 21252232 PMCID: PMC3060533 DOI: 10.1074/jbc.m110.169722] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2010] [Revised: 12/27/2010] [Indexed: 11/06/2022] Open
Abstract
Myosin phosphatase is a heterotrimeric holoenzyme consisting of myosin phosphatase-targeting subunit 1 (MYPT1), a catalytic subunit of PP1Cβ, and a 20-kDa subunit of an unknown function. We have previously reported that myosin phosphatase also controls mitosis, apparently by antagonizing polo-like kinase 1 (PLK1). Here we found that depletion of MYPT1 by siRNA led to precocious chromatid segregation when HeLa cells were arrested at metaphase by a proteasome inhibitor, MG132, or by Cdc20 depletion. Consistently, cyclin B1 and securin were not degraded, indicating that the chromatid segregation is independent of the anaphase-promoting complex/cyclosome. Precocious segregation induced by MYPT1 depletion requires PLK1 activity because a PLK1 inhibitor, BI-2536, blocked precocious segregation. Furthermore, the expression of an unphosphorylatable mutant of SA2 (SCC3 homologue 2), a subunit of the cohesin complex, prevented precocious chromatid segregation induced by MYPT1 depletion. It has been shown that SA2 at centromeres is protected from phosphorylation by PP2A phosphatase recruited by Shugoshin (Sgo1), whereas SA2 along chromosome arms is phosphorylated by PLK1, leading to SA2 dissociation at chromosome arms. Taken together, our results suggest that hyperactivation of PLK1 caused by MYPT1 reduction could override the counteracting PP2A phosphatase, resulting in precocious chromatid segregation. We propose that SA2 at the centromeres is protected by two phosphatases. One is PP2A directly dephosphorylating SA2, and the other is myosin phosphatase counteracting PLK1.
Collapse
Affiliation(s)
- Fumio Matsumura
- From the Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854
| | - Yoshihiko Yamakita
- From the Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854
| | - Shigeko Yamashiro
- From the Department of Molecular Biology and Biochemistry, Rutgers University, Piscataway, New Jersey 08854
| |
Collapse
|
39
|
Human Cdc14B promotes progression through mitosis by dephosphorylating Cdc25 and regulating Cdk1/cyclin B activity. PLoS One 2011; 6:e14711. [PMID: 21379580 PMCID: PMC3040744 DOI: 10.1371/journal.pone.0014711] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2010] [Accepted: 01/23/2011] [Indexed: 12/18/2022] Open
Abstract
Entry into and progression through mitosis depends on phosphorylation and dephosphorylation of key substrates. In yeast, the nucleolar phosphatase Cdc14 is pivotal for exit from mitosis counteracting Cdk1-dependent phosphorylations. Whether hCdc14B, the human homolog of yeast Cdc14, plays a similar function in mitosis is not yet known. Here we show that hCdc14B serves a critical role in regulating progression through mitosis, which is distinct from hCdc14A. Unscheduled overexpression of hCdc14B delays activation of two master regulators of mitosis, Cdc25 and Cdk1, and slows down entry into mitosis. Depletion of hCdc14B by RNAi prevents timely inactivation of Cdk1/cyclin B and dephosphorylation of Cdc25, leading to severe mitotic defects, such as delay of metaphase/anaphase transition, lagging chromosomes, multipolar spindles and binucleation. The results demonstrate that hCdc14B-dependent modulation of Cdc25 phosphatase and Cdk1/cyclin B activity is tightly linked to correct chromosome segregation and bipolar spindle formation, processes that are required for proper progression through mitosis and maintenance of genomic stability.
Collapse
|
40
|
Potapova TA, Sivakumar S, Flynn JN, Li R, Gorbsky GJ. Mitotic progression becomes irreversible in prometaphase and collapses when Wee1 and Cdc25 are inhibited. Mol Biol Cell 2011; 22:1191-206. [PMID: 21325631 PMCID: PMC3078080 DOI: 10.1091/mbc.e10-07-0599] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Activation of Cdk1 is rapid and switch-like due to positive feedback mechanisms. When Cdk1 is fully on, cells are capable of M-to-G1 transition. Inhibition of positive feedback prevents rapid Cdk1 activation and induces a mitotic “collapse” phenotype characterized by the dephosphorylation of mitotic substrates without cyclin B proteolysis. Mitosis requires precise coordination of multiple global reorganizations of the nucleus and cytoplasm. Cyclin-dependent kinase 1 (Cdk1) is the primary upstream kinase that directs mitotic progression by phosphorylation of a large number of substrate proteins. Cdk1 activation reaches the peak level due to positive feedback mechanisms. By inhibiting Cdk chemically, we showed that, in prometaphase, when Cdk1 substrates approach the peak of their phosphorylation, cells become capable of proper M-to-G1 transition. We interfered with the molecular components of the Cdk1-activating feedback system through use of chemical inhibitors of Wee1 and Myt1 kinases and Cdc25 phosphatases. Inhibition of Wee1 and Myt1 at the end of the S phase led to rapid Cdk1 activation and morphologically normal mitotic entry, even in the absence of G2. Dampening Cdc25 phosphatases simultaneously with Wee1 and Myt1 inhibition prevented Cdk1/cyclin B kinase activation and full substrate phosphorylation and induced a mitotic “collapse,” a terminal state characterized by the dephosphorylation of mitotic substrates without cyclin B proteolysis. This was blocked by the PP1/PP2A phosphatase inhibitor, okadaic acid. These findings suggest that the positive feedback in Cdk activation serves to overcome the activity of Cdk-opposing phosphatases and thus sustains forward progression in mitosis.
Collapse
|
41
|
Clément A, Solnica-Krezel L, Gould KL. The Cdc14B phosphatase contributes to ciliogenesis in zebrafish. Development 2011; 138:291-302. [PMID: 21177342 DOI: 10.1242/dev.055038] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Progression through the cell cycle relies on oscillation of cyclin-dependent kinase (Cdk) activity. One mechanism for downregulating Cdk signaling is to activate opposing phosphatases. The Cdc14 family of phosphatases counteracts Cdk1 phosphorylation in diverse organisms to allow proper exit from mitosis and cytokinesis. However, the role of the vertebrate CDC14 phosphatases, CDC14A and CDC14B, in re-setting the cell for interphase remains unclear. To understand Cdc14 function in vertebrates, we cloned the zebrafish cdc14b gene and used antisense morpholino oligonucleotides and an insertional mutation to inhibit its function during early development. Loss of Cdc14B function led to an array of phenotypes, including hydrocephaly, curved body, kidney cysts and left-right asymmetry defects, reminiscent of zebrafish mutants with defective cilia. Indeed, we report that motile and primary cilia were shorter in cdc14b-deficient embryos. We also demonstrate that Cdc14B function in ciliogenesis requires its phosphatase activity and can be dissociated from its function in cell cycle control. Finally, we propose that Cdc14B plays a role in the regulation of cilia length in a pathway independent of fibroblast growth factor (FGF). This first study of a loss of function of a Cdc14 family member in a vertebrate organism reveals a new role for Cdc14B in ciliogenesis and consequently in a number of developmental processes.
Collapse
Affiliation(s)
- Aurélie Clément
- Howard Hughes Medical Institute and Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA
| | | | | |
Collapse
|
42
|
DeLuca KF, Lens SMA, DeLuca JG. Temporal changes in Hec1 phosphorylation control kinetochore-microtubule attachment stability during mitosis. J Cell Sci 2011; 124:622-34. [PMID: 21266467 DOI: 10.1242/jcs.072629] [Citation(s) in RCA: 184] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Precise control of the attachment strength between kinetochores and spindle microtubules is essential to preserve genomic stability. Aurora B kinase has been implicated in regulating the stability of kinetochore-microtubule attachments but its relevant kinetochore targets in cells remain unclear. Here, we identify multiple serine residues within the N-terminus of the kinetochore protein Hec1 that are phosphorylated in an Aurora-B-kinase-dependent manner during mitosis. On all identified target sites, Hec1 phosphorylation at kinetochores is high in early mitosis and decreases significantly as chromosomes bi-orient. Furthermore, once dephosphorylated, Hec1 is not highly rephosphorylated in response to loss of kinetochore-microtubule attachment or tension. We find that a subpopulation of Aurora B kinase remains localized at the outer kinetochore even upon Hec1 dephosphorylation, suggesting that Hec1 phosphorylation by Aurora B might not be regulated wholly by spatial positioning of the kinase. Our results define a role for Hec1 phosphorylation in kinetochore-microtubule destabilization and error correction in early mitosis and for Hec1 dephosphorylation in maintaining stable attachments in late mitosis.
Collapse
Affiliation(s)
- Keith F DeLuca
- Department of Biochemistry and Molecular Biology, Colorado State University, Fort Collins, CO 80523, USA
| | | | | |
Collapse
|
43
|
Wicky S, Tjandra H, Schieltz D, Yates J, Kellogg DR. The Zds proteins control entry into mitosis and target protein phosphatase 2A to the Cdc25 phosphatase. Mol Biol Cell 2010; 22:20-32. [PMID: 21119008 PMCID: PMC3016974 DOI: 10.1091/mbc.e10-06-0487] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The Wee1 kinase restrains entry into mitosis by phosphorylating and inhibiting cyclin-dependent kinase 1 (Cdk1). The Cdc25 phosphatase promotes entry into mitosis by removing Cdk1 inhibitory phosphorylation. Experiments in diverse systems have established that Wee1 and Cdc25 are regulated by protein phosphatase 2A (PP2A), but a full understanding of the function and regulation of PP2A in entry into mitosis has remained elusive. In budding yeast, entry into mitosis is controlled by a specific form of PP2A that is associated with the Cdc55 regulatory subunit (PP2A(Cdc55)). We show here that related proteins called Zds1 and Zds2 form a tight stoichiometric complex with PP2A(Cdc55) and target its activity to Cdc25 but not to Wee1. Conditional inactivation of the Zds proteins revealed that their function is required primarily at entry into mitosis. In addition, Zds1 undergoes cell cycle-dependent changes in phosphorylation. Together, these observations define a role for the Zds proteins in controlling specific functions of PP2A(Cdc55) and suggest that upstream signals that regulate PP2A(Cdc55) may play an important role in controlling entry into mitosis.
Collapse
Affiliation(s)
- Sidonie Wicky
- Department of Molecular, Cell, and Developmental Biology, Univ. of California, Santa Cruz, CA 95064, USA
| | | | | | | | | |
Collapse
|
44
|
Hernandez-Verdun D, Roussel P, Thiry M, Sirri V, Lafontaine DLJ. The nucleolus: structure/function relationship in RNA metabolism. WILEY INTERDISCIPLINARY REVIEWS-RNA 2010; 1:415-31. [PMID: 21956940 DOI: 10.1002/wrna.39] [Citation(s) in RCA: 179] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The nucleolus is the ribosome factory of the cells. This is the nuclear domain where ribosomal RNAs are synthesized, processed, and assembled with ribosomal proteins. Here we describe the classical tripartite organization of the nucleolus in mammals, reflecting ribosomal gene transcription and pre-ribosomal RNA (pre-rRNA) processing efficiency: fibrillar center, dense fibrillar component, and granular component. We review the nucleolar organization across evolution from the bipartite organization in yeast to the tripartite organization in humans. We discuss the basic principles of nucleolar assembly and nucleolar structure/function relationship in RNA metabolism. The control of nucleolar assembly is presented as well as the role of pre-existing machineries and pre-rRNAs inherited from the previous cell cycle. In addition, nucleoli carry many essential extra ribosomal functions and are closely linked to cellular homeostasis and human health. The last part of this review presents recent advances in nucleolar dysfunctions in human pathology such as cancer and virus infections that modify the nucleolar organization.
Collapse
Affiliation(s)
- Danièle Hernandez-Verdun
- Nuclei and cell cycle, Institut Jacques Monod-UMR 7592 CNRS, Université Paris Diderot, 75205 Paris cedex 13, France.
| | | | | | | | | |
Collapse
|
45
|
Schmitz MHA, Held M, Janssens V, Hutchins JRA, Hudecz O, Ivanova E, Goris J, Trinkle-Mulcahy L, Lamond AI, Poser I, Hyman AA, Mechtler K, Peters JM, Gerlich DW. Live-cell imaging RNAi screen identifies PP2A-B55alpha and importin-beta1 as key mitotic exit regulators in human cells. Nat Cell Biol 2010; 12:886-93. [PMID: 20711181 PMCID: PMC3839080 DOI: 10.1038/ncb2092] [Citation(s) in RCA: 265] [Impact Index Per Article: 18.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2010] [Accepted: 07/02/2010] [Indexed: 01/20/2023]
Abstract
When vertebrate cells exit mitosis various cellular structures are re-organized to build functional interphase cells. This depends on Cdk1 (cyclin dependent kinase 1) inactivation and subsequent dephosphorylation of its substrates. Members of the protein phosphatase 1 and 2A (PP1 and PP2A) families can dephosphorylate Cdk1 substrates in biochemical extracts during mitotic exit, but how this relates to postmitotic reassembly of interphase structures in intact cells is not known. Here, we use a live-cell imaging assay and RNAi knockdown to screen a genome-wide library of protein phosphatases for mitotic exit functions in human cells. We identify a trimeric PP2A-B55alpha complex as a key factor in mitotic spindle breakdown and postmitotic reassembly of the nuclear envelope, Golgi apparatus and decondensed chromatin. Using a chemically induced mitotic exit assay, we find that PP2A-B55alpha functions downstream of Cdk1 inactivation. PP2A-B55alpha isolated from mitotic cells had reduced phosphatase activity towards the Cdk1 substrate, histone H1, and was hyper-phosphorylated on all subunits. Mitotic PP2A complexes co-purified with the nuclear transport factor importin-beta1, and RNAi depletion of importin-beta1 delayed mitotic exit synergistically with PP2A-B55alpha. This demonstrates that PP2A-B55alpha and importin-beta1 cooperate in the regulation of postmitotic assembly mechanisms in human cells.
Collapse
Affiliation(s)
- Michael H. A. Schmitz
- Institute of Biochemistry, Swiss Federal Institute of Technology Zurich (ETHZ), Schafmattstrasse 18, CH-8093 Zurich, Switzerland
- Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Michael Held
- Institute of Biochemistry, Swiss Federal Institute of Technology Zurich (ETHZ), Schafmattstrasse 18, CH-8093 Zurich, Switzerland
- Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Veerle Janssens
- Laboratory of Protein Phosphorylation and Proteomics, Department of Molecular Cell Biology, Faculty of Medicine, KU Leuven, Gasthuisberg O&N1, Herestraat 49 Box 901, B-3000 Leuven, Belgium
| | | | - Otto Hudecz
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Elitsa Ivanova
- Laboratory of Protein Phosphorylation and Proteomics, Department of Molecular Cell Biology, Faculty of Medicine, KU Leuven, Gasthuisberg O&N1, Herestraat 49 Box 901, B-3000 Leuven, Belgium
| | - Jozef Goris
- Laboratory of Protein Phosphorylation and Proteomics, Department of Molecular Cell Biology, Faculty of Medicine, KU Leuven, Gasthuisberg O&N1, Herestraat 49 Box 901, B-3000 Leuven, Belgium
| | - Laura Trinkle-Mulcahy
- Department of Cellular & Molecular Medicine and the Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, ON K1H 8M5, Canada
| | - Angus I. Lamond
- Wellcome Trust Centre for Gene Regulation & Expression, MSI/WTB/JBC Complex, University of Dundee, Dundee, DD1 5EH, UK
| | - Ina Poser
- Max-Planck-Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
| | - Anthony A. Hyman
- Max-Planck-Institute for Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
| | - Karl Mechtler
- Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
- Institute of Molecular Biotechnology of the Austrian Academy of Sciences, Dr. Bohr-Gasse 3, 1030 Vienna, Austria
| | - Jan-Michael Peters
- Institute of Molecular Pathology, Dr. Bohr-Gasse 7, 1030 Vienna, Austria
| | - Daniel W. Gerlich
- Institute of Biochemistry, Swiss Federal Institute of Technology Zurich (ETHZ), Schafmattstrasse 18, CH-8093 Zurich, Switzerland
- Marine Biological Laboratory, Woods Hole, MA 02543, USA
| |
Collapse
|
46
|
Jin Z, Wallace L, Harper SQ, Yang J. PP2A:B56{epsilon}, a substrate of caspase-3, regulates p53-dependent and p53-independent apoptosis during development. J Biol Chem 2010; 285:34493-502. [PMID: 20807766 DOI: 10.1074/jbc.m110.169581] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is one of the most abundantly expressed serine/threonine protein phosphatases. A large body of evidence suggests that PP2A is a tumor suppressor and plays critical roles in regulating apoptosis. PP2A is a heterotrimeric protein complex. Its substrate specificity, localization, and activity are regulated by regulatory subunits of PP2A. A recent study has demonstrated that single nucleotide polymorphism in B56ε (PPP2R5E), a B56 family regulatory subunit of PP2A, is associated with human soft tissue sarcoma. This raises the possibility that B56ε is involved in tumorigenesis and plays important roles in regulating apoptosis. However, this hypothesis has not been tested experimentally. Our previous studies revealed that B56ε regulates a number of developmental signaling pathways during early embryonic patterning. Here we report novel functions of B56ε in regulating apoptosis. We provide evidence that B56ε has both anti- and pro-apoptotic functions. B56ε suppresses p53-independent apoptosis during neural development, but triggers p53-dependent apoptosis. Mechanistically, B56ε regulates the p53-dependent apoptotic pathway solely through controlling the stability of p53 protein. In addition to its function in regulating apoptosis, we show that B56ε undergoes proteolytic cleavage. The cleavage of B56ε is mediated by caspase-3 and occurs on the carboxyl side of an evolutionarily conserved N-terminal "DKXD" motif. These results demonstrate that B56ε, a substrate of caspase-3, is an essential regulator of apoptosis. So far, we have identified an alternative translation isoform and a caspase cleavage product of B56ε. The significance of post-transcriptional regulation of B56ε is discussed.
Collapse
Affiliation(s)
- Zhigang Jin
- Department of Pediatrics, Research Institute at Nationwide Children's Hospital, Ohio State University, Columbus, Ohio 43205, USA
| | | | | | | |
Collapse
|
47
|
CCDC6 represses CREB1 activity by recruiting histone deacetylase 1 and protein phosphatase 1. Oncogene 2010; 29:4341-51. [PMID: 20498639 DOI: 10.1038/onc.2010.179] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
RET/papillary thyroid carcinoma 1 (PTC1) oncogene is frequently activated in human PTCs. It is characterized by the fusion of the intracellular kinase-encoding domain of RET to the first 101 amino acids of CCDC6. The aim of our work is to characterize the function of the CCDC6 protein to better understand the function of its truncation, that results in the loss of the expression of one allele, in the process of thyroid carcinogenesis. Here, we report that CCDC6 interacts with CREB1 and represses its transcriptional activity by recruiting histone deacetylase 1 and protein phosphatase 1 proteins at the CRE site of the CREB1 target genes. Finally, we show an increased CREB1 phosphorylation and activity in PTCs carrying the RET/PTC1 oncogene. Consistently, an increased expression of two known CREB1 target genes, AREG and cyclin A, was observed in this subgroup of thyroid papillary carcinomas. Therefore, the repression of CREB1 activity by CCDC6 has a critical function in the development of human thyroid papillary carcinomas carrying RET/PTC1 activation.
Collapse
|
48
|
C-terminal domain phosphorylation of ERK3 controlled by Cdk1 and Cdc14 regulates its stability in mitosis. Biochem J 2010; 428:103-11. [PMID: 20236090 DOI: 10.1042/bj20091604] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
ERK3 (extracellular-signal-regulated kinase 3) is an atypical MAPK (mitogen-activated protein kinase) that is suggested to play a role in cell-cycle progression and cellular differentiation. However, it is not known whether the function of ERK3 is regulated during the cell cycle. In the present paper, we report that ERK3 is stoichiometrically hyperphosphorylated during entry into mitosis and is dephosphorylated at the M-->G1 transition. The phosphorylation of ERK3 is associated with the accumulation of the protein in mitosis. In vitro phosphorylation of a series of ERK3-deletion mutants by mitotic cell extracts revealed that phosphorylation is confined to the unique C-terminal extension of the protein. Using MS analysis, we identified four novel phosphorylation sites, Ser684, Ser688, Thr698 and Ser705, located at the extreme C-terminus of ERK3. All four sites are followed by a proline residue. We have shown that purified cyclin B-Cdk1 (cyclindependent kinase 1) phosphorylates these sites in vitro and demonstrate that Cdk1 acts as a major Thr698 kinase in vivo. Reciprocally, we found that the phosphatases Cdc14A and Cdc14B (Cdc is cell-division cycle) bind to ERK3 and reverse its C-terminal phosphorylation in mitosis. Importantly, alanine substitution of the four C-terminal phosphorylation sites markedly decreased the half-life of ERK3 in mitosis, thereby linking phosphorylation to the stabilization of the kinase. The results of the present study identify a novel regulatory mechanism of ERK3 that operates in a cell-cycle-dependent manner.
Collapse
|
49
|
Fragilities caused by dosage imbalance in regulation of the budding yeast cell cycle. PLoS Genet 2010; 6:e1000919. [PMID: 20421994 PMCID: PMC2858678 DOI: 10.1371/journal.pgen.1000919] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2009] [Accepted: 03/22/2010] [Indexed: 12/11/2022] Open
Abstract
Cells can maintain their functions despite fluctuations in intracellular parameters, such as protein activities and gene expression levels. This commonly observed biological property of cells is called robustness. On the other hand, these parameters have different limitations, each reflecting the property of the subsystem containing the parameter. The budding yeast cell cycle is quite fragile upon overexpression of CDC14, but is robust upon overexpression of ESP1. The gene products of both CDC14 and ESP1 are regulated by 1∶1 binding with their inhibitors (Net1 and Pds1), and a mathematical model predicts the extreme fragility of the cell cycle upon overexpression of CDC14 and ESP1 caused by dosage imbalance between these genes. However, it has not been experimentally shown that dosage imbalance causes fragility of the cell cycle. In this study, we measured the quantitative genetic interactions of these genes by performing combinatorial “genetic tug-of-war” experiments. We first showed experimental evidence that dosage imbalance between CDC14 and NET1 causes fragility. We also showed that fragility arising from dosage imbalance between ESP1 and PDS1 is masked by CDH1 and CLB2. The masking function of CLB2 was stabilization of Pds1 by its phosphorylation. We finally modified Chen's model according to our findings. We thus propose that dosage imbalance causes fragility in biological systems. Normal cell functioning is dependent on balance between protein interactions and gene regulations. Although the balance is often perturbed by environmental changes, mutations, and noise in biochemical reactions, cellular systems can maintain their function despite these perturbations. This property of cells, called robustness, is now considered to be a design principle of biological systems and has become a central theme for systems biology. We previously developed an experimental method designated “genetic tug-of-war,” in which we assessed the robustness of cellular systems upon overexpression of certain genes, especially that of the budding yeast cell cycle. Although the yeast cell cycle can be maintained despite significant overexpression of most genes within the system, the cell cycle halts upon just two-fold overexpression of M phase phosphatase CDC14. In this study, we experimentally showed that this fragility is caused by dosage imbalance between CDC14 and NET1. Interestingly, fragility of regulation of separase gene ESP1, potentially caused by dosage imbalance, was masked by regulation of other factors such as CDH1 and CLB2. We thus propose that dosage imbalance causes fragility in biological systems.
Collapse
|
50
|
Meyer H, Drozdowska A, Dobrynin G. A role for Cdc48/p97 and Aurora B in controlling chromatin condensation during exit from mitosis. Biochem Cell Biol 2010; 88:23-8. [PMID: 20130676 DOI: 10.1139/o09-119] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During cell division, chromosomes condense so that the replicated chromatids can be segregated by the mitotic spindle. While condensation is governed by cyclin-dependent kinase 1 (Cdk1) during mitotic entry and early mitosis, it is still poorly understood how condensation is maintained during anaphase after Cdk1 inactivation, and how decondensation is triggered in telophase. Here, we review recent reports that point to a novel role of Aurora B kinase in maintaining condensation and preventing premature nuclear envelope formation during exit from mitosis. Timely decondensation and nuclear envelope formation at the end of mitosis may then be triggered by two mechanisms. One is removing Aurora B phosphorylation marks from chromatin by specific phosphatases. The other is removing and inactivating Aurora B kinase itself by the ubiquitin system. We have recently provided evidence that the AAA ATPase Cdc48/p97 plays a central role in the inactivation of Aurora B, as it extracts ubiquitinated Aurora B from chromosomes and thus reduces chromatinassociated Aurora B activity.
Collapse
Affiliation(s)
- Hemmo Meyer
- Institute of Biochemistry, ETH Zurich, Zurich 8093, Switzerland.
| | | | | |
Collapse
|