1
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Kapoor S, Adhikary K, Kotak S. PP2A-B55 SUR-6 promotes nuclear envelope breakdown in C. elegans embryos. Cell Rep 2023; 42:113495. [PMID: 37995185 DOI: 10.1016/j.celrep.2023.113495] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Revised: 09/25/2023] [Accepted: 11/09/2023] [Indexed: 11/25/2023] Open
Abstract
Nuclear envelope (NE) disassembly during mitosis is critical to ensure faithful segregation of the genetic material. NE disassembly is a phosphorylation-dependent process wherein mitotic kinases hyper-phosphorylate lamina and nucleoporins to initiate nuclear envelope breakdown (NEBD). In this study, we uncover an unexpected role of the PP2A phosphatase B55SUR-6 in NEBD during the first embryonic division of Caenorhabditis elegans embryo. B55SUR-6 depletion delays NE permeabilization and stabilizes lamina and nucleoporins. As a result, the merging of parental genomes and chromosome segregation is impaired. NEBD defect upon B55SUR-6 depletion is not due to delayed mitotic onset or mislocalization of mitotic kinases. Importantly, we demonstrate that microtubule-dependent mechanical forces synergize with B55SUR-6 for efficient NEBD. Finally, our data suggest that the lamin LMN-1 is likely a bona fide target of PP2A-B55SUR-6. These findings establish a model highlighting biochemical crosstalk between kinases, PP2A-B55SUR-6 phosphatase, and microtubule-generated mechanical forces in timely NE dissolution.
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Affiliation(s)
- Sukriti Kapoor
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India
| | - Kuheli Adhikary
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India
| | - Sachin Kotak
- Department of Microbiology and Cell Biology (MCB), Indian Institute of Science (IISc), Bangalore 560012, India.
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2
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Corno A, Cordeiro MH, Allan LA, Lim Q, Harrington E, Smith RJ, Saurin AT. A bifunctional kinase-phosphatase module balances mitotic checkpoint strength and kinetochore-microtubule attachment stability. EMBO J 2023; 42:e112630. [PMID: 37712330 PMCID: PMC10577578 DOI: 10.15252/embj.2022112630] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2022] [Revised: 08/23/2023] [Accepted: 08/28/2023] [Indexed: 09/16/2023] Open
Abstract
Two major mechanisms safeguard genome stability during mitosis: the mitotic checkpoint delays mitosis until all chromosomes have attached to microtubules, and the kinetochore-microtubule error-correction pathway keeps this attachment process free from errors. We demonstrate here that the optimal strength and dynamics of these processes are set by a kinase-phosphatase pair (PLK1-PP2A) that engage in negative feedback from adjacent phospho-binding motifs on the BUB complex. Uncoupling this feedback to skew the balance towards PLK1 produces a strong checkpoint, hypostable microtubule attachments and mitotic delays. Conversely, skewing the balance towards PP2A causes a weak checkpoint, hyperstable microtubule attachments and chromosome segregation errors. These phenotypes are associated with altered BUB complex recruitment to KNL1-MELT motifs, implicating PLK1-PP2A in controlling auto-amplification of MELT phosphorylation. In support, KNL1-BUB disassembly becomes contingent on PLK1 inhibition when KNL1 is engineered to contain excess MELT motifs. This elevates BUB-PLK1/PP2A complex levels on metaphase kinetochores, stabilises kinetochore-microtubule attachments, induces chromosome segregation defects and prevents KNL1-BUB disassembly at anaphase. Together, these data demonstrate how a bifunctional PLK1/PP2A module has evolved together with the MELT motifs to optimise BUB complex dynamics and ensure accurate chromosome segregation.
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Affiliation(s)
- Andrea Corno
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Marilia H Cordeiro
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Lindsey A Allan
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Qian‐Wei Lim
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Elena Harrington
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Richard J Smith
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
| | - Adrian T Saurin
- Cellular and Systems Medicine, School of MedicineUniversity of DundeeDundeeUK
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3
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Quiogue AR, Sumiyoshi E, Fries A, Chuang CH, Bowerman B. Microtubules oppose cortical actomyosin-driven membrane ingression during C. elegans meiosis I polar body extrusion. PLoS Genet 2023; 19:e1010984. [PMID: 37782660 PMCID: PMC10569601 DOI: 10.1371/journal.pgen.1010984] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Revised: 10/12/2023] [Accepted: 09/19/2023] [Indexed: 10/04/2023] Open
Abstract
During C. elegans oocyte meiosis I cytokinesis and polar body extrusion, cortical actomyosin is locally remodeled to assemble a contractile ring that forms within and remains part of a much larger and actively contractile cortical actomyosin network. This network both mediates contractile ring dynamics and generates shallow ingressions throughout the oocyte cortex during polar body extrusion. Based on our analysis of requirements for CLS-2, a member of the CLASP family of proteins that stabilize microtubules, we recently proposed that a balance of actomyosin-mediated tension and microtubule-mediated stiffness limits membrane ingression throughout the oocyte during meiosis I polar body extrusion. Here, using live cell imaging and fluorescent protein fusions, we show that CLS-2 is part of a group of kinetochore proteins, including the scaffold KNL-1 and the kinase BUB-1, that also co-localize during meiosis I to structures called linear elements, which are present within the assembling oocyte spindle and also are distributed throughout the oocyte in proximity to, but appearing to underlie, the actomyosin cortex. We further show that KNL-1 and BUB-1, like CLS-2, promote the proper organization of sub-cortical microtubules and also limit membrane ingression throughout the oocyte. Moreover, nocodazole or taxol treatment to destabilize or stabilize oocyte microtubules leads to, respectively, excess or decreased membrane ingression throughout the oocyte. Furthermore, taxol treatment, and genetic backgrounds that elevate the levels of cortically associated microtubules, both suppress excess membrane ingression in cls-2 mutant oocytes. We propose that linear elements influence the organization of sub-cortical microtubules to generate a stiffness that limits cortical actomyosin-driven membrane ingression throughout the oocyte during meiosis I polar body extrusion. We discuss the possibility that this regulation of sub-cortical microtubule dynamics facilitates actomyosin contractile ring dynamics during C. elegans oocyte meiosis I cell division.
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Affiliation(s)
- Alyssa R. Quiogue
- Institute of Molecular Biology, University of Oregon, Eugen, Oregon, United States of America
| | - Eisuke Sumiyoshi
- Institute of Molecular Biology, University of Oregon, Eugen, Oregon, United States of America
| | - Adam Fries
- Institute of Molecular Biology, University of Oregon, Eugen, Oregon, United States of America
- Imaging Core, Office of the Vice President for Research University of Oregon, Eugene, Oregon, United States of America
| | - Chien-Hui Chuang
- Institute of Molecular Biology, University of Oregon, Eugen, Oregon, United States of America
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugen, Oregon, United States of America
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4
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Nguyen H, Kettenbach AN. Substrate and phosphorylation site selection by phosphoprotein phosphatases. Trends Biochem Sci 2023; 48:713-725. [PMID: 37173206 PMCID: PMC10523993 DOI: 10.1016/j.tibs.2023.04.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 04/11/2023] [Accepted: 04/13/2023] [Indexed: 05/15/2023]
Abstract
Dynamic protein phosphorylation and dephosphorylation are essential regulatory mechanisms that ensure proper cellular signaling and biological functions. Deregulation of either reaction has been implicated in several human diseases. Here, we focus on the mechanisms that govern the specificity of the dephosphorylation reaction. Most cellular serine/threonine dephosphorylation is catalyzed by 13 highly conserved phosphoprotein phosphatase (PPP) catalytic subunits, which form hundreds of holoenzymes by binding to regulatory and scaffolding subunits. PPP holoenzymes recognize phosphorylation site consensus motifs and interact with short linear motifs (SLiMs) or structural elements distal to the phosphorylation site. We review recent advances in understanding the mechanisms of PPP site-specific dephosphorylation preference and substrate recruitment and highlight examples of their interplay in the regulation of cell division.
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Affiliation(s)
- Hieu Nguyen
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA
| | - Arminja N Kettenbach
- Biochemistry and Cell Biology, Geisel School of Medicine at Dartmouth College, Hanover, NH 03755, USA; Dartmouth Cancer Center, Lebanon, NH 03756, USA.
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5
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Quiogue AR, Sumiyoshi E, Fries A, Chuang CH, Bowerman B. Cortical microtubules oppose actomyosin-driven membrane ingression during C. elegans meiosis I polar body extrusion. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.26.542508. [PMID: 37292632 PMCID: PMC10245968 DOI: 10.1101/2023.05.26.542508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
During C. elegans oocyte meiosis I, cortical actomyosin is locally remodeled to assemble a contractile ring near the spindle. In contrast to mitosis, when most cortical actomyosin converges into a contractile ring, the small oocyte ring forms within and remains part of a much larger and actively contractile cortical actomyosin network. This network both mediates contractile ring dynamics and generates shallow ingressions throughout the oocyte cortex during polar body extrusion. Based on our analysis of requirements for CLS-2, a member of the CLASP family of proteins that stabilize microtubules, we recently proposed that a balance of actomyosin-mediated tension and microtubule-mediated stiffness are required for contractile ring assembly within the oocyte cortical actomyosin network. Here, using live cell imaging and fluorescent protein fusions, we show that CLS-2 is part of a complex of kinetochore proteins, including the scaffold KNL-1 and the kinase BUB-1, that also co-localize to patches distributed throughout the oocyte cortex during meiosis I. By reducing their function, we further show that KNL-1 and BUB-1, like CLS-2, are required for cortical microtubule stability, to limit membrane ingression throughout the oocyte, and for meiotic contractile ring assembly and polar body extrusion. Moreover, nocodazole or taxol treatment to destabilize or stabilize oocyte microtubules, respectively, leads to excess or decreased membrane ingression throughout the oocyte and defective polar body extrusion. Finally, genetic backgrounds that elevate cortical microtubule levels suppress the excess membrane ingression in cls-2 mutant oocytes. These results support our hypothesis that CLS-2, as part of a sub-complex of kinetochore proteins that also co-localize to patches throughout the oocyte cortex, stabilizes microtubules to stiffen the oocyte cortex and limit membrane ingression throughout the oocyte, thereby facilitating contractile ring dynamics and the successful completion of polar body extrusion during meiosis I.
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Affiliation(s)
| | | | - Adam Fries
- Institute of Molecular Biology
- Imaging Core, Office of the Vice President for Research, University of Oregon, Eugene, OR USA 97403
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6
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Taylor SJP, Bel Borja L, Soubigou F, Houston J, Cheerambathur DK, Pelisch F. BUB-1 and CENP-C recruit PLK-1 to control chromosome alignment and segregation during meiosis I in C. elegans oocytes. eLife 2023; 12:e84057. [PMID: 37067150 PMCID: PMC10156168 DOI: 10.7554/elife.84057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2022] [Accepted: 04/14/2023] [Indexed: 04/18/2023] Open
Abstract
Phosphorylation is a key post-translational modification that is utilised in many biological processes for the rapid and reversible regulation of protein localisation and activity. Polo-like kinase 1 (PLK-1) is essential for both mitotic and meiotic cell divisions, with key functions being conserved in eukaryotes. The roles and regulation of PLK-1 during mitosis have been well characterised. However, the discrete roles and regulation of PLK-1 during meiosis have remained obscure. Here, we used Caenorhabditis elegans oocytes to show that PLK-1 plays distinct roles in meiotic spindle assembly and/or stability, chromosome alignment and segregation, and polar body extrusion during meiosis I. Furthermore, by a combination of live imaging and biochemical analysis we identified the chromosomal recruitment mechanisms of PLK-1 during C. elegans oocyte meiosis. The spindle assembly checkpoint kinase BUB-1 directly recruits PLK-1 to the kinetochore and midbivalent while the chromosome arm population of PLK-1 depends on a direct interaction with the centromeric-associated protein CENP-CHCP-4. We found that perturbing both BUB-1 and CENP-CHCP-4 recruitment of PLK-1 leads to severe meiotic defects, resulting in highly aneuploid oocytes. Overall, our results shed light on the roles played by PLK-1 during oocyte meiosis and provide a mechanistic understanding of PLK-1 targeting to meiotic chromosomes.
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Affiliation(s)
- Samuel JP Taylor
- Centre for Gene Regulation and Expression, Sir James Black Centre, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - Laura Bel Borja
- Centre for Gene Regulation and Expression, Sir James Black Centre, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - Flavie Soubigou
- Centre for Gene Regulation and Expression, Sir James Black Centre, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - Jack Houston
- Ludwig Institute for Cancer Research, San Diego BranchLa JollaUnited States
| | - Dhanya K Cheerambathur
- Wellcome Centre for Cell Biology & Institute of Cell Biology, School of Biological Sciences, University of EdinburghEdinburghUnited Kingdom
| | - Federico Pelisch
- Centre for Gene Regulation and Expression, Sir James Black Centre, School of Life Sciences, University of DundeeDundeeUnited Kingdom
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7
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Macaisne N, Bellutti L, Laband K, Edwards F, Pitayu-Nugroho L, Gervais A, Ganeswaran T, Geoffroy H, Maton G, Canman JC, Lacroix B, Dumont J. Synergistic stabilization of microtubules by BUB-1, HCP-1, and CLS-2 controls microtubule pausing and meiotic spindle assembly. eLife 2023; 12:e82579. [PMID: 36799894 PMCID: PMC10005782 DOI: 10.7554/elife.82579] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Accepted: 02/16/2023] [Indexed: 02/18/2023] Open
Abstract
During cell division, chromosome segregation is orchestrated by a microtubule-based spindle. Interaction between spindle microtubules and kinetochores is central to the bi-orientation of chromosomes. Initially dynamic to allow spindle assembly and kinetochore attachments, which is essential for chromosome alignment, microtubules are eventually stabilized for efficient segregation of sister chromatids and homologous chromosomes during mitosis and meiosis I, respectively. Therefore, the precise control of microtubule dynamics is of utmost importance during mitosis and meiosis. Here, we study the assembly and role of a kinetochore module, comprised of the kinase BUB-1, the two redundant CENP-F orthologs HCP-1/2, and the CLASP family member CLS-2 (hereafter termed the BHC module), in the control of microtubule dynamics in Caenorhabditis elegans oocytes. Using a combination of in vivo structure-function analyses of BHC components and in vitro microtubule-based assays, we show that BHC components stabilize microtubules, which is essential for meiotic spindle formation and accurate chromosome segregation. Overall, our results show that BUB-1 and HCP-1/2 do not only act as targeting components for CLS-2 at kinetochores, but also synergistically control kinetochore-microtubule dynamics by promoting microtubule pause. Together, our results suggest that BUB-1 and HCP-1/2 actively participate in the control of kinetochore-microtubule dynamics in the context of an intact BHC module to promote spindle assembly and accurate chromosome segregation in meiosis.
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Affiliation(s)
- Nicolas Macaisne
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | - Laura Bellutti
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | - Kimberley Laband
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | - Frances Edwards
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | | | - Alison Gervais
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | | | - Hélène Geoffroy
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | - Gilliane Maton
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
| | - Julie C Canman
- Columbia University; Department of Pathology and Cell BiologyNew YorkUnited States
| | - Benjamin Lacroix
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), CNRS UMR 5237, Université de MontpellierMontpellierFrance
| | - Julien Dumont
- Université Paris Cité, CNRS, Institut Jacques Monod, F-75013ParisFrance
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8
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Zhang Y, Song C, Wang L, Jiang H, Zhai Y, Wang Y, Fang J, Zhang G. Zombies Never Die: The Double Life Bub1 Lives in Mitosis. Front Cell Dev Biol 2022; 10:870745. [PMID: 35646932 PMCID: PMC9136299 DOI: 10.3389/fcell.2022.870745] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Accepted: 04/06/2022] [Indexed: 11/17/2022] Open
Abstract
When eukaryotic cells enter mitosis, dispersed chromosomes move to the cell center along microtubules to form a metaphase plate which facilitates the accurate chromosome segregation. Meanwhile, kinetochores not stably attached by microtubules activate the spindle assembly checkpoint and generate a wait signal to delay the initiation of anaphase. These events are highly coordinated. Disruption of the coordination will cause severe problems like chromosome gain or loss. Bub1, a conserved serine/threonine kinase, plays important roles in mitosis. After extensive studies in the last three decades, the role of Bub1 on checkpoint has achieved a comprehensive understanding; its role on chromosome alignment also starts to emerge. In this review, we summarize the latest development of Bub1 on supporting the two mitotic events. The essentiality of Bub1 in higher eukaryotic cells is also discussed. At the end, some undissolved questions are raised for future study.
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Affiliation(s)
- Yuqing Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Chunlin Song
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Lei Wang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Hongfei Jiang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
| | - Yujing Zhai
- School of Public Health, Qingdao University, Qingdao, China
| | - Ying Wang
- School of Public Health, Qingdao University, Qingdao, China
| | - Jing Fang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
| | - Gang Zhang
- The Cancer Institute, The Affiliated Hospital of Qingdao University, Qingdao, China
- *Correspondence: Jing Fang, ; Gang Zhang,
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9
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Lu T, Smit RB, Soueid H, Mains PE. STRIPAK regulation of katanin microtubule severing in the Caenorhabditis elegans embryo. Genetics 2022; 221:iyac043. [PMID: 35298637 PMCID: PMC9071564 DOI: 10.1093/genetics/iyac043] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2022] [Accepted: 03/15/2022] [Indexed: 11/14/2022] Open
Abstract
Microtubule severing plays important role in cell structure and cell division. The microtubule severing protein katanin, composed of the MEI-1/MEI-2 subunits in Caenorhabditis elegans, is required for oocyte meiotic spindle formation; however, it must be inactivated for mitosis to proceed as continued katanin expression is lethal. Katanin activity is regulated by 2 ubiquitin-based protein degradation pathways. Another ubiquitin ligase, HECD-1, the homolog of human HECTD1/HECT domain E3 ubiquitin protein ligase 1, regulates katanin activity without affecting katanin levels. In other organisms, HECD-1 is a component of the striatin-interacting kinase phosphatase complex, which affects cell proliferation and a variety of signaling pathways. Here we conducted a systematic screen of how mutations in striatin-interacting kinase phosphatase components affect katanin function in C. elegans. Striatin-interacting kinase phosphatase core components (FARL-11, CASH-1, LET-92, and GCK-1) were katanin inhibitors in mitosis and activators in meiosis, much like HECD-1. By contrast, variable components (SLMP-1, OTUB-2) functioned as activators of katanin activity in mitosis, indicating they may function to alter striatin-interacting kinase phosphatase core function. The core component CCM-3 acted as an inhibitor at both divisions, while other components (MOB-4, C49H3.6) showed weak interactions with katanin mutants. Additional experiments indicate that katanin may be involved with the centralspindlin complex and a tubulin chaperone. HECD-1 shows ubiquitous expression in the cytoplasm throughout meiosis and early development. The differing functions of the different subunits could contribute to the diverse functions of the striatin-interacting kinase phosphatase complex in C. elegans and other organisms.
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Affiliation(s)
- Tammy Lu
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AL T2N 4N1, Canada
| | - Ryan B Smit
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AL T2N 4N1, Canada
| | - Hanifa Soueid
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AL T2N 4N1, Canada
| | - Paul E Mains
- Department of Biochemistry and Molecular Biology, Alberta Children’s Hospital Research Institute, University of Calgary, Calgary, AL T2N 4N1, Canada
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10
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Barski MS, Minnell JJ, Maertens GN. PP2A Phosphatase as an Emerging Viral Host Factor. Front Cell Infect Microbiol 2021; 11:725615. [PMID: 34422684 PMCID: PMC8371333 DOI: 10.3389/fcimb.2021.725615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2021] [Accepted: 07/20/2021] [Indexed: 12/12/2022] Open
Abstract
Protein phosphatase 2A (PP2A) is one of the most ubiquitous cellular proteins and is responsible for the vast majority of Ser/Thr phosphatase activity in eukaryotes. PP2A is a heterotrimer, and its assembly, intracellular localization, enzymatic activity, and substrate specificity are subject to dynamic regulation. Each of its subunits can be targeted by viral proteins to hijack and modulate its activity and downstream signaling to the advantage of the virus. Binding to PP2A is known to be essential to the life cycle of many viruses and seems to play a particularly crucial role for oncogenic viruses, which utilize PP2A to transform infected cells through controlling the cell cycle and apoptosis. Here we summarise the latest developments in the field of PP2A viral targeting; in particular recent discoveries of PP2A hijacking through molecular mimicry of a B56-specific motif by several different viruses. We also discuss the potential as well as shortcomings for therapeutic intervention in the face of our current understanding of viral PP2A targeting.
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Affiliation(s)
| | | | - Goedele Noella Maertens
- Department of Infectious Disease, Section of Molecular Virology, St Mary’s Hospital, Imperial College London, London, United Kingdom
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11
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Jang JK, Gladstein AC, Das A, Shapiro JG, Sisco ZL, McKim KS. Multiple pools of PP2A regulate spindle assembly, kinetochore attachments and cohesion in Drosophila oocytes. J Cell Sci 2021; 134:jcs254037. [PMID: 34297127 PMCID: PMC8325958 DOI: 10.1242/jcs.254037] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 06/14/2021] [Indexed: 01/06/2023] Open
Abstract
Meiosis in female oocytes lacks centrosomes, the microtubule-organizing centers. In Drosophila oocytes, meiotic spindle assembly depends on the chromosomal passenger complex (CPC). To investigate the mechanisms that regulate Aurora B activity, we examined the role of protein phosphatase 2A (PP2A) in Drosophila oocyte meiosis. We found that both forms of PP2A, B55 and B56, antagonize the Aurora B spindle assembly function, suggesting that a balance between Aurora B and PP2A activity maintains the oocyte spindle during meiosis I. PP2A-B56, which has a B subunit encoded by two partially redundant paralogs, wdb and wrd, is also required for maintenance of sister chromatid cohesion, establishment of end-on microtubule attachments, and metaphase I arrest in oocytes. WDB recruitment to the centromeres depends on BUBR1, MEI-S332 and kinetochore protein SPC105R. Although BUBR1 stabilizes microtubule attachments in Drosophila oocytes, it is not required for cohesion maintenance during meiosis I. We propose at least three populations of PP2A-B56 regulate meiosis, two of which depend on SPC105R and a third that is associated with the spindle.
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Affiliation(s)
| | | | | | | | | | - Kim S. McKim
- Waksman Institute, Rutgers, The State University of New Jersey, Piscataway, NJ 08854, USA
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12
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Lei WL, Qian WP, Sun QY. Critical Functions of PP2A-Like Protein Phosphotases in Regulating Meiotic Progression. Front Cell Dev Biol 2021; 9:638559. [PMID: 33718377 PMCID: PMC7947259 DOI: 10.3389/fcell.2021.638559] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 02/08/2021] [Indexed: 01/31/2023] Open
Abstract
Meiosis is essential to the continuity of life in sexually-reproducing organisms through the formation of haploid gametes. Unlike somatic cells, the germ cells undergo two successive rounds of meiotic divisions after a single cycle of DNA replication, resulting in the decrease in ploidy. In humans, errors in meiotic progression can cause infertility and birth defects. Post-translational modifications, such as phosphorylation, ubiquitylation and sumoylation have emerged as important regulatory events in meiosis. There are dynamic equilibrium of protein phosphorylation and protein dephosphorylation in meiotic cell cycle process, regulated by a conservative series of protein kinases and protein phosphatases. Among these protein phosphatases, PP2A, PP4, and PP6 constitute the PP2A-like subfamily within the serine/threonine protein phosphatase family. Herein, we review recent discoveries and explore the role of PP2A-like protein phosphatases during meiotic progression.
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Affiliation(s)
- Wen-Long Lei
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, China
| | - Wei-Ping Qian
- Department of Reproductive Medicine, Peking University Shenzhen Hospital, Shenzhen, China
| | - Qing-Yuan Sun
- Fertility Preservation Lab, Reproductive Medicine Center, Guangdong Second Provincial General Hospital, Guangzhou, China
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