1
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Di Cesare G, Lombardi G, Zeidman P, Urgen BA, Sciutti A, Friston KJ, Rizzolatti G. Two distinct networks for encoding goals and forms of action: An effective connectivity study. Proc Natl Acad Sci U S A 2024; 121:e2402282121. [PMID: 38885383 PMCID: PMC11214092 DOI: 10.1073/pnas.2402282121] [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: 02/09/2024] [Accepted: 05/06/2024] [Indexed: 06/20/2024] Open
Abstract
Goal-directed actions are characterized by two main features: the content (i.e., the action goal) and the form, called vitality forms (VF) (i.e., how actions are executed). It is well established that both the action content and the capacity to understand the content of another's action are mediated by a network formed by a set of parietal and frontal brain areas. In contrast, the neural bases of action forms (e.g., gentle or rude actions) have not been characterized. However, there are now studies showing that the observation and execution of actions endowed with VF activate, in addition to the parieto-frontal network, the dorso-central insula (DCI). In the present study, we established-using dynamic causal modeling (DCM)-the direction of information flow during observation and execution of actions endowed with gentle and rude VF in the human brain. Based on previous fMRI studies, the selected nodes for the DCM comprised the posterior superior temporal sulcus (pSTS), the inferior parietal lobule (IPL), the premotor cortex (PM), and the DCI. Bayesian model comparison showed that, during action observation, two streams arose from pSTS: one toward IPL, concerning the action goal, and one toward DCI, concerning the action vitality forms. During action execution, two streams arose from PM: one toward IPL, concerning the action goal and one toward DCI concerning action vitality forms. This last finding opens an interesting question concerning the possibility to elicit VF in two distinct ways: cognitively (from PM to DCI) and affectively (from DCI to PM).
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Affiliation(s)
- Giuseppe Di Cesare
- Department of Medicine and Surgery, University of Parma, Parma43125, Italy
- Cognitive Architecture for Collaborative Technologies Unit, Italian Institute of Technology, Genova16163, Italy
| | - Giada Lombardi
- Cognitive Architecture for Collaborative Technologies Unit, Italian Institute of Technology, Genova16163, Italy
- Department of Informatics, Bioengineering, Robotics and Systems Engineering, University of Genoa, Genoa16145, Italy
| | - Peter Zeidman
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, LondonWC1N 3BG, United Kingdom
| | - Burcu A. Urgen
- Department of Psychology, Bilkent University, Ankara06800, Turkey
- Department of Neuroscience, Bilkent University, Ankara06800, Turkey
- Aysel Sabuncu Brain Research Center & National Magnetic Resonance Research Center, Bilkent University, Ankara06800, Turkey
| | - Alessandra Sciutti
- Cognitive Architecture for Collaborative Technologies Unit, Italian Institute of Technology, Genova16163, Italy
| | - Karl J. Friston
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, LondonWC1N 3BG, United Kingdom
| | - Giacomo Rizzolatti
- Department of Medicine and Surgery, University of Parma, Parma43125, Italy
- Institute of Neuroscience, National Research Council of Italy, Parma43125, Italy
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2
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Bement WM, Goryachev AB, Miller AL, von Dassow G. Patterning of the cell cortex by Rho GTPases. Nat Rev Mol Cell Biol 2024; 25:290-308. [PMID: 38172611 DOI: 10.1038/s41580-023-00682-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2023] [Indexed: 01/05/2024]
Abstract
The Rho GTPases - RHOA, RAC1 and CDC42 - are small GTP binding proteins that regulate basic biological processes such as cell locomotion, cell division and morphogenesis by promoting cytoskeleton-based changes in the cell cortex. This regulation results from active (GTP-bound) Rho GTPases stimulating target proteins that, in turn, promote actin assembly and myosin 2-based contraction to organize the cortex. This basic regulatory scheme, well supported by in vitro studies, led to the natural assumption that Rho GTPases function in vivo in an essentially linear matter, with a given process being initiated by GTPase activation and terminated by GTPase inactivation. However, a growing body of evidence based on live cell imaging, modelling and experimental manipulation indicates that Rho GTPase activation and inactivation are often tightly coupled in space and time via signalling circuits and networks based on positive and negative feedback. In this Review, we present and discuss this evidence, and we address one of the fundamental consequences of coupled activation and inactivation: the ability of the Rho GTPases to self-organize, that is, direct their own transition from states of low order to states of high order. We discuss how Rho GTPase self-organization results in the formation of diverse spatiotemporal cortical patterns such as static clusters, oscillatory pulses, travelling wave trains and ring-like waves. Finally, we discuss the advantages of Rho GTPase self-organization and pattern formation for cell function.
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Affiliation(s)
- William M Bement
- Center for Quantitative Cell Imaging, Department of Integrative Biology, University of Wisconsin-Madison, Madison, WI, USA.
| | - Andrew B Goryachev
- Center for Engineering Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, UK.
| | - Ann L Miller
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI, USA.
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3
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Bock F, Dong X, Li S, Viquez OM, Sha E, Tantengco M, Hennen EM, Plosa E, Ramezani A, Brown KL, Whang YM, Terker AS, Arroyo JP, Harrison DG, Fogo A, Brakebusch CH, Pozzi A, Zent R. Rac1 promotes kidney collecting duct repair by mechanically coupling cell morphology to mitotic entry. SCIENCE ADVANCES 2024; 10:eadi7840. [PMID: 38324689 PMCID: PMC10849615 DOI: 10.1126/sciadv.adi7840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 01/03/2024] [Indexed: 02/09/2024]
Abstract
Prolonged obstruction of the ureter, which leads to injury of the kidney collecting ducts, results in permanent structural damage, while early reversal allows for repair. Cell structure is defined by the actin cytoskeleton, which is dynamically organized by small Rho guanosine triphosphatases (GTPases). In this study, we identified the Rho GTPase, Rac1, as a driver of postobstructive kidney collecting duct repair. After the relief of ureteric obstruction, Rac1 promoted actin cytoskeletal reconstitution, which was required to maintain normal mitotic morphology allowing for successful cell division. Mechanistically, Rac1 restricted excessive actomyosin activity that stabilized the negative mitotic entry kinase Wee1. This mechanism ensured mechanical G2-M checkpoint stability and prevented premature mitotic entry. The repair defects following injury could be rescued by direct myosin inhibition. Thus, Rac1-dependent control of the actin cytoskeleton integrates with the cell cycle to mediate kidney tubular repair by preventing dysmorphic cells from entering cell division.
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Affiliation(s)
- Fabian Bock
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Xinyu Dong
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Shensen Li
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Olga M. Viquez
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Eric Sha
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew Tantengco
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Elizabeth M. Hennen
- Department of Biomedical Engineering, Vanderbilt University, Nashville, TN, USA
| | - Erin Plosa
- Division of Neonatology, Department of Pediatrics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alireza Ramezani
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, USA
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | - Kyle L. Brown
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Young Mi Whang
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Andrew S. Terker
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Juan Pablo Arroyo
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David G. Harrison
- Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Agnes Fogo
- Department of Pathology, Microbiology and Immunology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Cord H. Brakebusch
- Biotech Research Center, University of Copenhagen, Copenhagen DK-2200, Denmark
| | - Ambra Pozzi
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Physiology and Molecular Biophysics, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Roy Zent
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Veterans Affairs Hospital, Tennessee Valley Healthcare System, Nashville, TN, USA
- Vanderbilt Center for Kidney Disease, Vanderbilt University Medical Center, Nashville, TN, USA
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN, USA
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4
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Jeruzalska E, Mazur AJ. The Role of non-muscle actin paralogs in cell cycle progression and proliferation. Eur J Cell Biol 2023; 102:151315. [PMID: 37099935 DOI: 10.1016/j.ejcb.2023.151315] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 04/14/2023] [Accepted: 04/17/2023] [Indexed: 04/28/2023] Open
Abstract
Uncontrolled cell proliferation leads to several pathologies, including cancer. Thus, this process must be tightly regulated. The cell cycle accounts for cell proliferation, and its progression is coordinated with changes in cell shape, for which cytoskeleton reorganization is responsible. Rearrangement of the cytoskeleton allows for its participation in the precise division of genetic material and cytokinesis. One of the main cytoskeletal components is filamentous actin-based structures. Mammalian cells have at least six actin paralogs, four of which are muscle-specific, while two, named β- and γ-actin, are abundantly present in all types of cells. This review summarizes the findings that establish the role of non-muscle actin paralogs in regulating cell cycle progression and proliferation. We discuss studies showing that the level of a given non-muscle actin paralog in a cell influences the cell's ability to progress through the cell cycle and, thus, proliferation. Moreover, we elaborate on the non-muscle actins' role in regulating gene transcription, interactions of actin paralogs with proteins involved in controlling cell proliferation, and the contribution of non-muscle actins to different structures in a dividing cell. The data cited in this review show that non-muscle actins regulate the cell cycle and proliferation through varying mechanisms. We point to the need for further studies addressing these mechanisms.
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Affiliation(s)
- Estera Jeruzalska
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Poland
| | - Antonina J Mazur
- Department of Cell Pathology, Faculty of Biotechnology, University of Wroclaw, Poland.
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5
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Ozugergin I, Piekny A. Diversity is the spice of life: An overview of how cytokinesis regulation varies with cell type. Front Cell Dev Biol 2022; 10:1007614. [PMID: 36420142 PMCID: PMC9676254 DOI: 10.3389/fcell.2022.1007614] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2022] [Accepted: 10/24/2022] [Indexed: 09/01/2023] Open
Abstract
Cytokinesis is required to physically cleave a cell into two daughters at the end of mitosis. Decades of research have led to a comprehensive understanding of the core cytokinesis machinery and how it is regulated in animal cells, however this knowledge was generated using single cells cultured in vitro, or in early embryos before tissues develop. This raises the question of how cytokinesis is regulated in diverse animal cell types and developmental contexts. Recent studies of distinct cell types in the same organism or in similar cell types from different organisms have revealed striking differences in how cytokinesis is regulated, which includes different threshold requirements for the structural components and the mechanisms that regulate them. In this review, we highlight these differences with an emphasis on pathways that are independent of the mitotic spindle, and operate through signals associated with the cortex, kinetochores, or chromatin.
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Affiliation(s)
- Imge Ozugergin
- Department of Biology, McGill University, Montreal, QC, Canada
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada
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6
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Anijs M, Devanna P, Vernes SC. ARHGEF39, a Gene Implicated in Developmental Language Disorder, Activates RHOA and Is Involved in Cell De-Adhesion and Neural Progenitor Cell Proliferation. Front Mol Neurosci 2022; 15:941494. [PMID: 35959104 PMCID: PMC9359124 DOI: 10.3389/fnmol.2022.941494] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Accepted: 06/21/2022] [Indexed: 11/13/2022] Open
Abstract
ARHGEF39 was previously implicated in developmental language disorder (DLD) via a functional polymorphism that can disrupt post-transcriptional regulation by microRNAs. ARHGEF39 is part of the family of Rho guanine nucleotide exchange factors (RhoGEFs) that activate small Rho GTPases to regulate a wide variety of cellular processes. However, little is known about the function of ARHGEF39, or how its function might contribute to neurodevelopment or related disorders. Here, we explore the molecular function of ARHGEF39 and show that it activates the Rho GTPase RHOA and that high ARHGEF39 expression in cell cultures leads to an increase of detached cells. To explore its role in neurodevelopment, we analyse published single cell RNA-sequencing data and demonstrate that ARHGEF39 is a marker gene for proliferating neural progenitor cells and that it is co-expressed with genes involved in cell division. This suggests a role for ARHGEF39 in neurogenesis in the developing brain. The co-expression of ARHGEF39 with other RHOA-regulating genes supports RHOA as substrate of ARHGEF39 in neural cells, and the involvement of RHOA in neuropsychiatric disorders highlights a potential link between ARHGEF39 and neurodevelopment and disorder. Understanding the GTPase substrate, co-expression network, and processes downstream of ARHGEF39 provide new avenues for exploring the mechanisms by which altered expression levels of ARHGEF39 may contribute to neurodevelopment and associated disorders.
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7
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Darp R, Vittoria MA, Ganem NJ, Ceol CJ. Oncogenic BRAF induces whole-genome doubling through suppression of cytokinesis. Nat Commun 2022; 13:4109. [PMID: 35840569 PMCID: PMC9287415 DOI: 10.1038/s41467-022-31899-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/07/2022] [Indexed: 11/29/2022] Open
Abstract
Melanomas and other solid tumors commonly have increased ploidy, with near-tetraploid karyotypes being most frequently observed. Such karyotypes have been shown to arise through whole-genome doubling events that occur during early stages of tumor progression. The generation of tetraploid cells via whole-genome doubling is proposed to allow nascent tumor cells the ability to sample various pro-tumorigenic genomic configurations while avoiding the negative consequences that chromosomal gains or losses have in diploid cells. Whereas a high prevalence of whole-genome doubling events has been established, the means by which whole-genome doubling arises is unclear. Here, we find that BRAFV600E, the most common mutation in melanomas, can induce whole-genome doubling via cytokinesis failure in vitro and in a zebrafish melanoma model. Mechanistically, BRAFV600E causes decreased activation and localization of RhoA, a critical cytokinesis regulator. BRAFV600E activity during G1/S phases of the cell cycle is required to suppress cytokinesis. During G1/S, BRAFV600E activity causes inappropriate centriole amplification, which is linked in part to inhibition of RhoA and suppression of cytokinesis. Together these data suggest that common abnormalities of melanomas linked to tumorigenesis - amplified centrosomes and whole-genome doubling events - can be induced by oncogenic BRAF and other mutations that increase RAS/MAPK pathway activity.
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Affiliation(s)
- Revati Darp
- University of Massachusetts Chan Medical School, Program in Molecular Medicine, Worcester, MA, USA
- University of Massachusetts Chan Medical School, Department of Molecular, Cellular and Cancer Biology, Worcester, MA, USA
| | - Marc A Vittoria
- Departments of Pharmacology and Experimental Therapeutics and Medicine, Division of Hematology and Oncology, Boston University School of Medicine, Boston, MA, USA
| | - Neil J Ganem
- Departments of Pharmacology and Experimental Therapeutics and Medicine, Division of Hematology and Oncology, Boston University School of Medicine, Boston, MA, USA
| | - Craig J Ceol
- University of Massachusetts Chan Medical School, Program in Molecular Medicine, Worcester, MA, USA.
- University of Massachusetts Chan Medical School, Department of Molecular, Cellular and Cancer Biology, Worcester, MA, USA.
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8
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Swider ZT, Michaud A, Leda M, Landino J, Goryachev AB, Bement WM. Cell cycle and developmental control of cortical excitability in Xenopus laevis. Mol Biol Cell 2022; 33:ar73. [PMID: 35594176 PMCID: PMC9635278 DOI: 10.1091/mbc.e22-01-0025] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Interest in cortical excitability—the ability of the cell cortex to generate traveling waves of protein activity—has grown considerably over the past 20 years. Attributing biological functions to cortical excitability requires an understanding of the natural behavior of excitable waves and the ability to accurately quantify wave properties. Here we have investigated and quantified the onset of cortical excitability in Xenopus laevis eggs and embryos and the changes in cortical excitability throughout early development. We found that cortical excitability begins to manifest shortly after egg activation. Further, we identified a close relationship between wave properties—such as wave frequency and amplitude—and cell cycle progression as well as cell size. Finally, we identified quantitative differences between cortical excitability in the cleavage furrow relative to nonfurrow cortical excitability and showed that these wave regimes are mutually exclusive.
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Affiliation(s)
- Zachary T Swider
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706
| | - Ani Michaud
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706
| | - Marcin Leda
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - Jennifer Landino
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann Arbor, Ann Arbor, MI 48109
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh EH9 3BF, UK
| | - William M Bement
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison Madison, WI 53706.,Center for Quantitative Cell Imaging, University of Wisconsin-Madison Madison, WI 53706.,Department of Integrative Biology, University of Wisconsin-Madison Madison, WI 53706
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9
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Wontakal SN, Britto M, Zhang H, Han Y, Gao C, Tannenbaum S, Durham BH, Lee MT, An X, Mishima M. RACGAP1 variants in a sporadic case of CDA III implicate the dysfunction of centralspindlin as the basis of the disease. Blood 2022; 139:1413-1418. [PMID: 34818416 PMCID: PMC8900277 DOI: 10.1182/blood.2021012334] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Accepted: 11/15/2021] [Indexed: 11/20/2022] Open
Affiliation(s)
- Sandeep N Wontakal
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY
| | - Mishan Britto
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
| | - Huan Zhang
- Laboratory of Membrane Biology, New York Blood Center, New York, NY
| | - Yongshuai Han
- Laboratory of Membrane Biology, New York Blood Center, New York, NY
| | - Chengjie Gao
- Laboratory of Membrane Biology, New York Blood Center, New York, NY
| | - Sarah Tannenbaum
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY; and
| | - Benjamin H Durham
- Department of Pathology and Cell Biology, Columbia University Irving Medical Center, New York, NY
- Department of Pathology, Memorial Sloan Kettering Cancer Center, New York, NY
| | - Margaret T Lee
- Department of Pediatrics, Columbia University Irving Medical Center, New York, NY; and
| | - Xiuli An
- Laboratory of Membrane Biology, New York Blood Center, New York, NY
| | - Masanori Mishima
- Centre for Mechanochemical Cell Biology & Division of Biomedical Sciences, Warwick Medical School, University of Warwick, Coventry, United Kingdom
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10
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Lopez Rioja A, Faulkner A, Mellor H. srGAP2 deactivates RhoA to control the duration of thrombin-mediated endothelial permeability. VASCULAR BIOLOGY (BRISTOL, ENGLAND) 2022; 4:K1-K10. [PMID: 35441126 PMCID: PMC9012936 DOI: 10.1530/vb-21-0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2022] [Accepted: 02/28/2022] [Indexed: 11/08/2022]
Abstract
The endothelial barrier is a tightly regulated gateway in the transport of material between circulation and the tissues. Inflammatory mediators such as thrombin are able to open paracellular spaces in the endothelial monolayer to allow the extravasation of plasma proteins and leukocytes. Here we show that the protein SLIT-ROBO Rho GTPase-activating protein 2 (srGAP2) plays a critical role in regulating the extent of thrombin-mediated opening. We show that srGAP2 is not required for normal barrier function in resting endothelial cells, but that depletion of srGAP2 significantly increases the magnitude and duration of junctional opening in response to thrombin. We show that srGAP2 acts to switch off RhoA signaling after the contraction phase of thrombin-induced permeability, allowing respreading of cells and reformation of the barrier. srGAP2 is also required for effective restoration of the barrier after treatment with two other vasoactive agents that active RhoA - TNFα and angiotensin II. Taken together, we show that srGAP2 has a general function in controlling RhoA signaling in endothelial permeability, acting to limit the degree and duration of opening, by triggering the switch from endothelial cell contraction to respreading.
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Affiliation(s)
- Alba Lopez Rioja
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
| | - Ashton Faulkner
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
| | - Harry Mellor
- School of Biochemistry, Biomedical Sciences Building, University of Bristol, Bristol, UK
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11
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Fixing the GAP: the role of RhoGAPs in cancer. Eur J Cell Biol 2022; 101:151209. [DOI: 10.1016/j.ejcb.2022.151209] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 01/29/2022] [Accepted: 02/08/2022] [Indexed: 12/12/2022] Open
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12
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EGF-induced nuclear translocation of SHCBP1 promotes bladder cancer progression through inhibiting RACGAP1-mediated RAC1 inactivation. Cell Death Dis 2022; 13:39. [PMID: 35013128 PMCID: PMC8748695 DOI: 10.1038/s41419-021-04479-w] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2021] [Revised: 12/01/2021] [Accepted: 12/14/2021] [Indexed: 12/12/2022]
Abstract
Bladder cancer is a highly heterogeneous and aggressive malignancy with a poor prognosis. EGF/EGFR activation causes the detachment of SHC-binding protein 1 (SHCBP1) from SHC adapter protein 1 (SHC1), which subsequently translocates into the nucleus and promotes cancer development via multiple signaling pathways. However, the role of the EGF-SHCBP1 axis in bladder cancer progression remains unexplored. Herein, we report that SHCBP1 is upregulated in bladder cancer tissues and cells, with cytoplasmic or nuclear localization. Released SHCBP1 responds to EGF stimulation by translocating into the nucleus following Ser273 phosphorylation. Depletion of SHCBP1 reduces EGF-induced cell migration and invasiveness of bladder cancer cells. Mechanistically, SHCBP1 binds to RACGAP1 via its N-terminal domain of amino acids 1 ~ 428, and this interaction is enhanced following EGF treatment. Furthermore, SHCBP1 facilitates cell migration by inhibiting RACGAP-mediated GTP-RAC1 inactivation, whose activity is indispensable for cell movement. Collectively, we demonstrate that the EGF-SHCBP1-RACGAP1-RAC1 axis acts as a novel regulatory mechanism of bladder cancer progression, which offers a new clinical therapeutic strategy to combat bladder cancer.
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13
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Koh SP, Pham NP, Piekny A. Seeing is believing: tools to study the role of Rho GTPases during cytokinesis. Small GTPases 2022; 13:211-224. [PMID: 34405757 PMCID: PMC9707540 DOI: 10.1080/21541248.2021.1957384] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Cytokinesis is required to cleave the daughter cells at the end of mitosis and relies on the spatiotemporal control of RhoA GTPase. Cytokinesis failure can lead to changes in cell fate or aneuploidy, which can be detrimental during development and/or can lead to cancer. However, our knowledge of the pathways that regulate RhoA during cytokinesis is limited, and the role of other Rho family GTPases is not clear. This is largely because the study of Rho GTPases presents unique challenges using traditional cell biological and biochemical methods, and they have pleiotropic functions making genetic studies difficult to interpret. The recent generation of optogenetic tools and biosensors that control and detect active Rho has overcome some of these challenges and is helping to elucidate the role of RhoA in cytokinesis. However, improvements are needed to reveal the role of other Rho GTPases in cytokinesis, and to identify the molecular mechanisms that control Rho activity. This review examines some of the outstanding questions in cytokinesis, and explores tools for the imaging and control of Rho GTPases.
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Affiliation(s)
- Su Pin Koh
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Nhat Phi Pham
- Department of Biology, Concordia University, Montreal, QC, Canada
| | - Alisa Piekny
- Department of Biology, Concordia University, Montreal, QC, Canada,CONTACT Alisa Piekny Department of Biology, Concordia University, 7141 Sherbrooke St. W, Montreal, QC, Canada
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14
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From primordial germ cells to spermatids in Caenorhabditis elegans. Semin Cell Dev Biol 2021; 127:110-120. [PMID: 34930663 DOI: 10.1016/j.semcdb.2021.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 11/17/2021] [Accepted: 12/07/2021] [Indexed: 12/24/2022]
Abstract
Development of a syncytial germline for gamete formation requires complex regulation of cytokinesis and cytoplasmic remodeling. Recently, several uncovered cellular events have been investigated in the Caenorhabditis elegans (C. elegans) germline. In these cellular processes, the factors involved in contractility are highly conserved with those of mitosis and meiosis. However, the underlying regulatory mechanisms are far more complicated than previously thought, likely due to the single syncytial germline structure. In this review, we highlight how the proteins involved in contractility ensure faithful cell division in different cellular contexts and how they contribute to maintaining intercellular bridge stability. In addition, we discuss the current understanding of the cellular events of cytokinesis and cytoplasmic remodeling during the development of the C. elegans germline, including progenitor germ cells, germ cells, and spermatocytes. Comparisons are made with relevant systems in Drosophila melanogaster (D. melanogaster) and other animal models.
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15
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Bian R, Dang W, Song X, Liu L, Jiang C, Yang Y, Li Y, Li L, Li X, Hu Y, Bao R, Liu Y. Rac GTPase activating protein 1 promotes gallbladder cancer via binding DNA ligase 3 to reduce apoptosis. Int J Biol Sci 2021; 17:2167-2180. [PMID: 34239347 PMCID: PMC8241731 DOI: 10.7150/ijbs.58857] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2021] [Accepted: 04/30/2021] [Indexed: 11/09/2022] Open
Abstract
Rac GTPase activating protein 1 (RACGAP1) has been characterized in the pathogenesis and progression of several malignancies, however, little is known regarding its role in the development of gallbladder cancer (GBC). This investigation seeks to describe the role of RACGAP1 and its associated molecular mechanisms in GBC. It was found that RACGAP1 was highly expressed in human GBC tissues, which was associated to poorer overall survival (OS). Gene knockdown of RACGAP1 hindered tumor cell proliferation and survival both in vitro and in vivo. We further identified that RACGAP1 was involved in DNA repair through its binding with DNA ligase 3 (LIG3), a crucial component of the alternative-non-homologous end joining (Alt-NHEJ) pathway. RACGAP1 regulated LIG3 expression independent of RhoA activity. RACGAP1 knockdown resulted in LIG3-dependent repair dysfunction, accumulated DNA damage and Poly(ADP-ribosyl) modification (PARylation) enhancement, leading to increased apoptosis and suppressed cell growth. We conclude that RACGAP1 exerts a tumor-promoting role via binding LIG3 to reduce apoptosis and facilitate cell growth in GBC, pointing to RACGAP1 as a potential therapeutic target for GBC.
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Affiliation(s)
- Rui Bian
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Wei Dang
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200092, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xiaoling Song
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200092, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Liguo Liu
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Chengkai Jiang
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yang Yang
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yongsheng Li
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Lin Li
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Xuechuan Li
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yunping Hu
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200092, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Runfa Bao
- Department of General Surgery and Laboratory of General Surgery, Xinhua Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200092, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Yingbin Liu
- Department of Biliary-Pancreatic Surgery, Renji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China.,Shanghai Key Laboratory of Biliary Tract Disease Research, Shanghai 200092, China.,State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200240, China
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16
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Abstract
During anaphase, a microtubule-containing structure called the midzone forms between the segregating chromosomes. The midzone is composed of an antiparallel array of microtubules and numerous microtubule-associated proteins that contribute to midzone formation and function. In many cells, the midzone is an important source of signals that specify the location of contractile ring assembly and constriction. The midzone also contributes to the events of anaphase by generating forces that impact chromosome segregation and spindle elongation; some midzone components contribute to both processes. The results of recent experiments have increased our understanding of the importance of the midzone, a microtubule array that has often been overlooked. This Journal of Cell Science at a Glance article will review, and illustrate on the accompanying poster, the organization, formation and dynamics of the midzone, and discuss open questions for future research.
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Affiliation(s)
- Patricia Wadsworth
- Department of Biology, Morrill Science Center, University of Massachusetts, 611 N. Pleasant Street, Amherst 01003, USA
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17
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Michaud A, Swider ZT, Landino J, Leda M, Miller AL, von Dassow G, Goryachev AB, Bement WM. Cortical excitability and cell division. Curr Biol 2021; 31:R553-R559. [PMID: 34033789 PMCID: PMC8358936 DOI: 10.1016/j.cub.2021.02.053] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
As the interface between the cell and its environment, the cell cortex must be able to respond to a variety of external stimuli. This is made possible in part by cortical excitability, a behavior driven by coupled positive and negative feedback loops that generate propagating waves of actin assembly in the cell cortex. Cortical excitability is best known for promoting cell protrusion and allowing the interpretation of and response to chemoattractant gradients in migrating cells. It has recently become apparent, however, that cortical excitability is involved in the response of the cortex to internal signals from the cell-cycle regulatory machinery and the spindle during cell division. Two overlapping functions have been ascribed to cortical excitability in cell division: control of cell division plane placement, and amplification of the activity of the small GTPase Rho at the equatorial cortex during cytokinesis. Here, we propose that cortical excitability explains several important yet poorly understood features of signaling during cell division. We also consider the potential advantages that arise from the use of cortical excitability as a signaling mechanism to regulate cortical dynamics in cell division.
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Affiliation(s)
- Ani Michaud
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA; Center for Quantitative Cell Imaging, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA
| | - Zachary T Swider
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA; Center for Quantitative Cell Imaging, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA
| | - Jennifer Landino
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann Arbor, 5264 Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI 48109-1085, USA
| | - Marcin Leda
- Centre for Synthetic and Systems Biology, University of Edinburgh, 2.03 C.H. Waddington Building, King's Buildings, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - Ann L Miller
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan-Ann Arbor, 5264 Biological Sciences Building, 1105 North University Avenue, Ann Arbor, MI 48109-1085, USA
| | - George von Dassow
- Oregon Institute of Marine Biology, University of Oregon, 63466 Boat Basin Road, Charleston, OR 97420, USA
| | - Andrew B Goryachev
- Centre for Synthetic and Systems Biology, University of Edinburgh, 2.03 C.H. Waddington Building, King's Buildings, University of Edinburgh, Max Born Crescent, Edinburgh EH9 3BF, UK
| | - William M Bement
- Cellular and Molecular Biology Graduate Program, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA; Center for Quantitative Cell Imaging, University of Wisconsin-Madison, 1525 Linden Drive, Madison, WI 53706, USA; Department of Integrative Biology, University of Wisconsin-Madison, 1117 West Johnson Street, Madison, WI 53706, USA.
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18
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Pal D, Ellis A, Sepúlveda-Ramírez SP, Salgado T, Terrazas I, Reyes G, De La Rosa R, Henson JH, Shuster CB. Rac and Arp2/3-Nucleated Actin Networks Antagonize Rho During Mitotic and Meiotic Cleavages. Front Cell Dev Biol 2020; 8:591141. [PMID: 33282870 PMCID: PMC7705106 DOI: 10.3389/fcell.2020.591141] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2020] [Accepted: 10/20/2020] [Indexed: 12/01/2022] Open
Abstract
In motile cells, the activities of the different Rho family GTPases are spatially segregated within the cell, and during cytokinesis there is evidence that this may also be the case. But while Rho’s role as the central organizer for contractile ring assembly is well established, the role of Rac and the branched actin networks it promotes is less well understood. To characterize the contributions of these proteins during cytokinesis, we manipulated Rac and Arp2/3 activity during mitosis and meiosis in sea urchin embryos and sea star oocytes. While neither Rac nor Arp2/3 were essential for early embryonic divisions, loss of either Rac or Arp2/3 activity resulted in polar body defects. Expression of activated Rac resulted in cytokinesis failure as early as the first division, and in oocytes, activated Rac suppressed both the Rho wave that traverses the oocyte prior to polar body extrusion as well as polar body formation itself. However, the inhibitory effect of Rac on cytokinesis, polar body formation and the Rho wave could be suppressed by effector-binding mutations or direct inhibition of Arp2/3. Together, these results suggest that Rac- and Arp2/3 mediated actin networks may directly antagonize Rho signaling, thus providing a potential mechanism to explain why Arp2/3-nucleated branched actin networks must be suppressed at the cell equator for successful cytokinesis.
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Affiliation(s)
- Debadrita Pal
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Andrea Ellis
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | | | - Torey Salgado
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Isabella Terrazas
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Gabriela Reyes
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - Richard De La Rosa
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
| | - John H Henson
- Department of Biology, Dickinson College, Carlisle, PA, United States
| | - Charles B Shuster
- Department of Biology, New Mexico State University, Las Cruces, NM, United States
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19
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The adaptor protein APPL2 controls glucose-stimulated insulin secretion via F-actin remodeling in pancreatic β-cells. Proc Natl Acad Sci U S A 2020; 117:28307-28315. [PMID: 33122440 DOI: 10.1073/pnas.2016997117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Filamentous actin (F-actin) cytoskeletal remodeling is critical for glucose-stimulated insulin secretion (GSIS) in pancreatic β-cells, and its dysregulation causes type 2 diabetes. The adaptor protein APPL1 promotes first-phase GSIS by up-regulating soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein expression. However, whether APPL2 (a close homology of APPL1 with the same domain organization) plays a role in β-cell functions is unknown. Here, we show that APPL2 enhances GSIS by promoting F-actin remodeling via the small GTPase Rac1 in pancreatic β-cells. β-cell specific abrogation of APPL2 impaired GSIS, leading to glucose intolerance in mice. APPL2 deficiency largely abolished glucose-induced first- and second-phase insulin secretion in pancreatic islets. Real-time live-cell imaging and phalloidin staining revealed that APPL2 deficiency abolished glucose-induced F-actin depolymerization in pancreatic islets. Likewise, knockdown of APPL2 expression impaired glucose-stimulated F-actin depolymerization and subsequent insulin secretion in INS-1E cells, which were attributable to the impairment of Ras-related C3 botulinum toxin substrate 1 (Rac1) activation. Treatment with the F-actin depolymerization chemical compounds or overexpression of gelsolin (a F-actin remodeling protein) rescued APPL2 deficiency-induced defective GSIS. In addition, APPL2 interacted with Rac GTPase activating protein 1 (RacGAP1) in a glucose-dependent manner via the bin/amphiphysin/rvs-pleckstrin homology (BAR-PH) domain of APPL2 in INS-1E cells and HEK293 cells. Concomitant knockdown of RacGAP1 expression reverted APPL2 deficiency-induced defective GSIS, F-actin remodeling, and Rac1 activation in INS-1E cells. Our data indicate that APPL2 interacts with RacGAP1 and suppresses its negative action on Rac1 activity and F-actin depolymerization thereby enhancing GSIS in pancreatic β-cells.
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20
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Carim SC, Kechad A, Hickson GRX. Animal Cell Cytokinesis: The Rho-Dependent Actomyosin-Anilloseptin Contractile Ring as a Membrane Microdomain Gathering, Compressing, and Sorting Machine. Front Cell Dev Biol 2020; 8:575226. [PMID: 33117802 PMCID: PMC7575755 DOI: 10.3389/fcell.2020.575226] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/07/2020] [Indexed: 12/19/2022] Open
Abstract
Cytokinesis is the last step of cell division that partitions the cellular organelles and cytoplasm of one cell into two. In animal cells, cytokinesis requires Rho-GTPase-dependent assembly of F-actin and myosin II (actomyosin) to form an equatorial contractile ring (CR) that bisects the cell. Despite 50 years of research, the precise mechanisms of CR assembly, tension generation and closure remain elusive. This hypothesis article considers a holistic view of the CR that, in addition to actomyosin, includes another Rho-dependent cytoskeletal sub-network containing the scaffold protein, Anillin, and septin filaments (collectively termed anillo-septin). We synthesize evidence from our prior work in Drosophila S2 cells that actomyosin and anillo-septin form separable networks that are independently anchored to the plasma membrane. This latter realization leads to a simple conceptual model in which CR assembly and closure depend upon the micro-management of the membrane microdomains to which actomyosin and anillo-septin sub-networks are attached. During CR assembly, actomyosin contractility gathers and compresses its underlying membrane microdomain attachment sites. These microdomains resist this compression, which builds tension. During CR closure, membrane microdomains are transferred from the actomyosin sub-network to the anillo-septin sub-network, with which they flow out of the CR as it advances. This relative outflow of membrane microdomains regulates tension, reduces the circumference of the CR and promotes actomyosin disassembly all at the same time. According to this hypothesis, the metazoan CR can be viewed as a membrane microdomain gathering, compressing and sorting machine that intrinsically buffers its own tension through coordination of actomyosin contractility and anillo-septin-membrane relative outflow, all controlled by Rho. Central to this model is the abandonment of the dogmatic view that the plasma membrane is always readily deformable by the underlying cytoskeleton. Rather, the membrane resists compression to build tension. The notion that the CR might generate tension through resistance to compression of its own membrane microdomain attachment sites, can account for numerous otherwise puzzling observations and warrants further investigation using multiple systems and methods.
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Affiliation(s)
- Sabrya C. Carim
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Amel Kechad
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Gilles R. X. Hickson
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
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21
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Munezane H, Oizumi H, Wakabayashi T, Nishio S, Hirasawa T, Sato T, Harada A, Yoshida T, Eguchi T, Yamanashi Y, Hashimoto T, Iwatsubo T. Roles of Collagen XXV and Its Putative Receptors PTPσ/δ in Intramuscular Motor Innervation and Congenital Cranial Dysinnervation Disorder. Cell Rep 2020; 29:4362-4376.e6. [PMID: 31875546 DOI: 10.1016/j.celrep.2019.11.112] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 09/23/2019] [Accepted: 11/26/2019] [Indexed: 10/25/2022] Open
Abstract
Intramuscular motor innervation is an essential process in neuromuscular development. Recently, mutations in COL25A1, encoding CLAC-P/collagen XXV, have been linked to the development of a congenital cranial dysinnervation disorder (CCDD). Yet the molecular mechanisms of intramuscular innervation and the etiology of CCDD related to COL25A1 have remained elusive. Here, we report that muscle-derived collagen XXV is indispensable for intramuscular innervation. In developing skeletal muscles, Col25a1 expression is tightly regulated by muscle excitation. In vitro and cell-based assays reveal a direct interaction between collagen XXV and receptor protein tyrosine phosphatases (PTPs) σ and δ. Motor explant assays show that expression of collagen XXV in target cells attracts motor axons, but this is inhibited by exogenous PTPσ/δ. CCDD mutations attenuate motor axon attraction by reducing collagen XXV-PTPσ/δ interaction. Overall, our study identifies PTPσ/δ as putative receptors for collagen XXV, implicating collagen XXV and PTPσ/δ in intramuscular innervation and a developmental ocular motor disorder.
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Affiliation(s)
- Haruka Munezane
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Hiroaki Oizumi
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tomoko Wakabayashi
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Department of Innovative Dementia Prevention, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
| | - Shu Nishio
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Tomoko Hirasawa
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Takashi Sato
- Laboratory of Developmental Biology and Metabolism, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan
| | - Akihiro Harada
- Department of Cell Biology, Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan
| | - Tomoyuki Yoshida
- Department of Molecular Neuroscience, University of Toyama, Toyama 930-0194, Japan
| | - Takahiro Eguchi
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Yuji Yamanashi
- Division of Genetics, Department of Cancer Biology, The Institute of Medical Science, The University of Tokyo, Tokyo 108-8639, Japan
| | - Tadafumi Hashimoto
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan; Department of Innovative Dementia Prevention, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan
| | - Takeshi Iwatsubo
- Department of Neuropathology, Graduate School of Medicine, The University of Tokyo, Tokyo 113-0033, Japan.
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22
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Profiling cytotoxic microRNAs in pediatric and adult glioblastoma cells by high-content screening, identification, and validation of miR-1300. Oncogene 2020; 39:5292-5306. [PMID: 32555332 PMCID: PMC7378045 DOI: 10.1038/s41388-020-1360-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2019] [Revised: 05/20/2020] [Accepted: 06/05/2020] [Indexed: 01/05/2023]
Abstract
MicroRNAs play an important role in the regulation of mRNA translation and have therapeutic potential in cancer and other diseases. To profile the landscape of microRNAs with significant cytotoxicity in the context of glioblastoma (GBM), we performed a high-throughput screen in adult and pediatric GBM cells using a synthetic oligonucleotide library representing all known human microRNAs. Bioinformatics analysis was used to refine this list and the top seven microRNAs were validated in a larger panel of GBM cells using state-of-the-art in vitro assays. The cytotoxic effect of our most relevant candidate was assessed in a preclinical model. Our screen identified ~100 significantly cytotoxic microRNAs with 70% concordance between cell lines. MicroRNA-1300 (miR-1300) was the most potent and robust candidate. We observed a striking binucleated phenotype in miR-1300 transfected cells due to cytokinesis failure followed by apoptosis. This was also observed in two stem-like patient-derived cultures. We identified the physiological role of miR-1300 as a regulator of endomitosis in megakaryocyte differentiation where blockade of cytokinesis is an essential step. In GBM cells, where miR-1300 is normally not expressed, the oncogene Epithelial Cell Transforming 2 (ECT2) was validated as a direct key target. ECT2 siRNA phenocopied the effects of miR-1300, and ECT2 overexpression led to rescue of miR-1300 induced binucleation. We showed that ectopic expression of miR-1300 led to decreased tumor growth in an orthotopic GBM model. Our screen provides a resource for the neuro-oncology community and identified miR-1300 as a novel regulator of endomitosis with translatable potential for therapeutic application.
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23
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Abstract
The active form of the small GTPase RhoA is necessary and sufficient for formation of a cytokinetic furrow in animal cells. Despite the conceptual simplicity of the process, the molecular mechanisms that control it are intricate and involve redundancy at multiple levels. Here, we discuss our current knowledge of the mechanisms underlying spatiotemporal regulation of RhoA during cytokinesis by upstream activators. The direct upstream activator, the RhoGEF Ect2, requires activation due to autoinhibition. Ect2 is primarily activated by the centralspindlin complex, which contains numerous domains that regulate its subcellular localization, oligomeric state, and Ect2 activation. We review the functions of these domains and how centralspindlin is regulated to ensure correctly timed, equatorial RhoA activation. Highlighting recent evidence, we propose that although centralspindlin does not always prominently accumulate on the plasma membrane, it is the site where it promotes RhoA activation during cytokinesis.
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24
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Holder J, Poser E, Barr FA. Getting out of mitosis: spatial and temporal control of mitotic exit and cytokinesis by PP1 and PP2A. FEBS Lett 2019; 593:2908-2924. [PMID: 31494926 DOI: 10.1002/1873-3468.13595] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 07/31/2019] [Accepted: 08/19/2019] [Indexed: 12/11/2022]
Abstract
Here, we will review the evidence showing that mitotic exit is initiated by regulated proteolysis and then driven by the PPP family of phosphoserine/threonine phosphatases. Rapid APC/CCDC20 and ubiquitin-dependent proteolysis of cyclin B and securin initiates sister chromatid separation, the first step of mitotic exit. Because proteolysis of Aurora and Polo family kinases dependent on APC/CCDH1 is relatively slow, this creates a new regulatory state, anaphase, different to G2 and M-phase. We will discuss how the CDK1-counteracting phosphatases PP1 and PP2A-B55, together with Aurora and Polo kinases, contribute to the temporal regulation and order of events in the different stages of mitotic exit from anaphase to cytokinesis. For PP2A-B55, these timing properties are created by the ENSA-dependent inhibitory pathway and differential recognition of phosphoserine and phosphothreonine. Finally, we will discuss how Aurora B and PP2A-B56 are needed for the spatial regulation of anaphase spindle formation and how APC/C-dependent destruction of PLK1 acts as a timer for abscission, the final event of cytokinesis.
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Affiliation(s)
- James Holder
- Department of Biochemistry, University of Oxford, UK
| | - Elena Poser
- Department of Biochemistry, University of Oxford, UK
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25
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Uroz M, Garcia-Puig A, Tekeli I, Elosegui-Artola A, Abenza JF, Marín-Llauradó A, Pujals S, Conte V, Albertazzi L, Roca-Cusachs P, Raya Á, Trepat X. Traction forces at the cytokinetic ring regulate cell division and polyploidy in the migrating zebrafish epicardium. NATURE MATERIALS 2019; 18:1015-1023. [PMID: 31160803 DOI: 10.1038/s41563-019-0381-9] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Accepted: 04/18/2019] [Indexed: 06/09/2023]
Abstract
Epithelial repair and regeneration are driven by collective cell migration and division. Both cellular functions involve tightly controlled mechanical events, but how physical forces regulate cell division in migrating epithelia is largely unknown. Here we show that cells dividing in the migrating zebrafish epicardium exert large cell-extracellular matrix (ECM) forces during cytokinesis. These forces point towards the division axis and are exerted through focal adhesions that connect the cytokinetic ring to the underlying ECM. When subjected to high loading rates, these cytokinetic focal adhesions prevent closure of the contractile ring, leading to multi-nucleation through cytokinetic failure. By combining a clutch model with experiments on substrates of different rigidity, ECM composition and ligand density, we show that failed cytokinesis is triggered by adhesion reinforcement downstream of increased myosin density. The mechanical interaction between the cytokinetic ring and the ECM thus provides a mechanism for the regulation of cell division and polyploidy that may have implications in regeneration and cancer.
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Affiliation(s)
- Marina Uroz
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
| | - Anna Garcia-Puig
- Center of Regenerative Medicine in Barcelona (CMRB), Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain
| | - Isil Tekeli
- Center of Regenerative Medicine in Barcelona (CMRB), Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain
| | - Alberto Elosegui-Artola
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
| | - Juan F Abenza
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
| | - Ariadna Marín-Llauradó
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
| | - Silvia Pujals
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
| | - Vito Conte
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Department of Biomedical Engineering and the Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Lorenzo Albertazzi
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- Department of Biomedical Engineering and the Institute for Complex Molecular Systems, Eindhoven University of Technology, Eindhoven, the Netherlands
| | - Pere Roca-Cusachs
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain
- University of Barcelona, Barcelona, Spain
| | - Ángel Raya
- Center of Regenerative Medicine in Barcelona (CMRB), Barcelona, Spain
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - Xavier Trepat
- Institute for Bioengineering of Catalonia (IBEC), The Barcelona Institute for Science and Technology (BIST), Barcelona, Spain.
- Centro de Investigación Biomédica en Red en Bioingeniería, Biomateriales y Nanomedicina (CIBER-BBN), Barcelona, Spain.
- University of Barcelona, Barcelona, Spain.
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain.
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26
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Verma V, Mogilner A, Maresca TJ. Classical and Emerging Regulatory Mechanisms of Cytokinesis in Animal Cells. BIOLOGY 2019; 8:biology8030055. [PMID: 31357447 PMCID: PMC6784142 DOI: 10.3390/biology8030055] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 07/05/2019] [Accepted: 07/23/2019] [Indexed: 12/12/2022]
Abstract
The primary goal of cytokinesis is to produce two daughter cells, each having a full set of chromosomes. To achieve this, cells assemble a dynamic structure between segregated sister chromatids called the contractile ring, which is made up of filamentous actin, myosin-II, and other regulatory proteins. Constriction of the actomyosin ring generates a cleavage furrow that divides the cytoplasm to produce two daughter cells. Decades of research have identified key regulators and underlying molecular mechanisms; however, many fundamental questions remain unanswered and are still being actively investigated. This review summarizes the key findings, computational modeling, and recent advances in understanding of the molecular mechanisms that control the formation of the cleavage furrow and cytokinesis.
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Affiliation(s)
- Vikash Verma
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA.
| | - Alex Mogilner
- Courant Institute of Mathematical Sciences, New York University, New York, NY 10012, USA
- Department of Biology, New York University, New York, NY 10012, USA
| | - Thomas J Maresca
- Biology Department, University of Massachusetts, Amherst, MA 01003, USA
- Molecular and Cellular Biology Graduate Program, University of Massachusetts, Amherst, MA 01003, USA
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27
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Yin C, Toiyama Y, Okugawa Y, Shigemori T, Yamamoto A, Ide S, Kitajima T, Fujikawa H, Yasuda H, Okita Y, Hiro J, Yoshiyama S, Ohi M, Araki T, Yao L, Kusunoki M. Rac GTPase-Activating Protein 1 (RACGAP1) as an Oncogenic Enhancer in Esophageal Carcinoma. Oncology 2019; 97:155-163. [PMID: 31216559 DOI: 10.1159/000500592] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2018] [Accepted: 04/24/2019] [Indexed: 11/19/2022]
Abstract
PURPOSE Rac GTPase-activating protein 1 (RACGAP1) is associated with cell proliferation, and there is much evidence of its oncogenic role. This study investigated the clinical importance and functional role of RACGAP1 in esophageal carcinoma (EC). METHODS A total of 81 EC patients were enrolled in the study. We assessed the immunohistochemical score of EC tissues and adjacent normal esophageal mucosae, and then performed multiple cell function tests by means of in vitro experiments to elucidate the functional role of RACGAP1 using RNA interference technology in EC cell lines. RESULTS RACGAP1 was significantly overexpressed in EC tissues compared with the adjacent normal esophageal mucosae (p < 0.0001). Moreover, RACGAP1 overexpression was significantly correlated with poor overall survival (p = 0.032) and disease-free survival (p = 0.012) in EC patients. High RACGAP1 expression was also significantly correlated with the presence of lymphatic invasion (p = 0.012), vessel invasion (p = 0.003), and advanced TNM (tumor-node-metastasis) stage (p = 0.046) in EC patients. In vitro analysis demonstrated that RACGAP1 was involved in the proliferation, tumorigenicity, invasion, migration, and anoikis resistance in EC cells. CONCLUSIONS RACGAP1 plays a pivotal role in EC development, suggesting that it could be used as an indicator of prognosis in EC patients.
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Affiliation(s)
- Chengzeng Yin
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan.,Department of Surgery, China-Japan Friendship Hospital, Beijing, China
| | - Yuji Toiyama
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan,
| | - Yoshinaga Okugawa
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Tsunehiko Shigemori
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Akira Yamamoto
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Shozo Ide
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Takahito Kitajima
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Hiroyuki Fujikawa
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Hiromi Yasuda
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Yoshiki Okita
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Junichiro Hiro
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Shigeyuki Yoshiyama
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Masaki Ohi
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Toshimitsu Araki
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
| | - Li Yao
- Department of Surgery, China-Japan Friendship Hospital, Beijing, China
| | - Masato Kusunoki
- Division of Reparative Medicine, Department of Gastrointestinal and Pediatric Surgery, Institute of Life Sciences, Mie University Graduate School of Medicine, Mie, Japan
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28
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Farina F, Ramkumar N, Brown L, Samandar Eweis D, Anstatt J, Waring T, Bithell J, Scita G, Thery M, Blanchoin L, Zech T, Baum B. Local actin nucleation tunes centrosomal microtubule nucleation during passage through mitosis. EMBO J 2019; 38:e99843. [PMID: 31015335 PMCID: PMC6545563 DOI: 10.15252/embj.201899843] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Revised: 04/02/2019] [Accepted: 04/04/2019] [Indexed: 12/19/2022] Open
Abstract
Cells going through mitosis undergo precisely timed changes in cell shape and organisation, which serve to ensure the fair partitioning of cellular components into the two daughter cells. These structural changes are driven by changes in actin filament and microtubule dynamics and organisation. While most evidence suggests that the two cytoskeletal systems are remodelled in parallel during mitosis, recent work in interphase cells has implicated the centrosome in both microtubule and actin nucleation, suggesting the potential for regulatory crosstalk between the two systems. Here, by using both in vitro and in vivo assays to study centrosomal actin nucleation as cells pass through mitosis, we show that mitotic exit is accompanied by a burst in cytoplasmic actin filament formation that depends on WASH and the Arp2/3 complex. This leads to the accumulation of actin around centrosomes as cells enter anaphase and to a corresponding reduction in the density of centrosomal microtubules. Taken together, these data suggest that the mitotic regulation of centrosomal WASH and the Arp2/3 complex controls local actin nucleation, which may function to tune the levels of centrosomal microtubules during passage through mitosis.
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Affiliation(s)
- Francesca Farina
- MRC-LMCB, UCL, London, UK
- IPLS, UCL, London, UK
- IFOM, the FIRC Institute of Molecular Oncology, University of Milan, Milan, Italy
- University of Grenoble, Grenoble, France
| | | | - Louise Brown
- Institute of Translational Medicine, Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | | | | | - Thomas Waring
- Institute of Translational Medicine, Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Jessica Bithell
- Institute of Translational Medicine, Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Giorgio Scita
- IFOM, the FIRC Institute of Molecular Oncology, University of Milan, Milan, Italy
- Department of Oncology and Hemato-Oncology, University of Milan, Milan, Italy
| | | | | | - Tobias Zech
- Institute of Translational Medicine, Cellular and Molecular Physiology, University of Liverpool, Liverpool, UK
| | - Buzz Baum
- MRC-LMCB, UCL, London, UK
- IPLS, UCL, London, UK
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29
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Kaibori Y, Saito Y, Nakayama Y. EphA2 phosphorylation at Ser897 by the Cdk1/MEK/ERK/RSK pathway regulates M-phase progression via maintenance of cortical rigidity. FASEB J 2019; 33:5334-5349. [PMID: 30668924 DOI: 10.1096/fj.201801519rr] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Successful cell division is accomplished by the proper formation of the mitotic spindle. Here, we show that EphA2 knockdown causes mitotic errors, including a delay in M-phase progression, asymmetric spindle positioning, multipolar spindles, and cell blebs. It has been known that EphA2 is phosphorylated at Tyr588, which is triggered by the ligand binding, and at Ser897 downstream of growth factor signaling. Upon mitotic entry, EphA2 is phosphorylated at Ser897, accompanied by a reduction in Tyr588 phosphorylation. This EphA2 phosphorylation at Ser897 is inhibited by MEK/ERK and 90 kDa ribosomal S6 kinase (RSK) inhibitors and is induced by the introduction of active cyclin-dependent kinase 1 (Cdk1) and cyclin B1. EphA2 knockdown-induced M-phase delay and cell blebs are rescued by wild type EphA2 expression but not by Ser897Ala mutant. The Ras homolog gene family member G (RhoG) guanine nucleotide exchange factor Ephexin4 interacts with EphA2 in a Ser897 phosphorylation-dependent manner, and its knockdown delays M-phase progression and causes RhoG delocalization. RhoG knockdown delays M-phase progression, and EphA2 knockdown-induced M-phase delay is partially rescued by the constitutively active RhoG mutant. These results suggest that, in EphA2-expressing cells, EphA2 phosphorylation at Ser897 participates in proper M-phase progression downstream of the Cdk1/MEK/ERK/RSK pathway because of its role in maintaining cortical rigidity via Ephexin4 and RhoG and thereby regulating mitotic spindle formation.-Kaibori, Y. Saito, Y., Nakayama, Y. EphA2 phosphorylation at Ser897 by the Cdk1/MEK/ERK/RSK pathway regulates M-phase progression via maintenance of cortical rigidity.
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Affiliation(s)
- Yuichiro Kaibori
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Youhei Saito
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
| | - Yuji Nakayama
- Department of Biochemistry and Molecular Biology, Kyoto Pharmaceutical University, Kyoto, Japan
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30
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Pintard L, Bowerman B. Mitotic Cell Division in Caenorhabditis elegans. Genetics 2019; 211:35-73. [PMID: 30626640 PMCID: PMC6325691 DOI: 10.1534/genetics.118.301367] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2018] [Accepted: 10/24/2018] [Indexed: 11/18/2022] Open
Abstract
Mitotic cell divisions increase cell number while faithfully distributing the replicated genome at each division. The Caenorhabditis elegans embryo is a powerful model for eukaryotic cell division. Nearly all of the genes that regulate cell division in C. elegans are conserved across metazoan species, including humans. The C. elegans pathways tend to be streamlined, facilitating dissection of the more redundant human pathways. Here, we summarize the virtues of C. elegans as a model system and review our current understanding of centriole duplication, the acquisition of pericentriolar material by centrioles to form centrosomes, the assembly of kinetochores and the mitotic spindle, chromosome segregation, and cytokinesis.
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Affiliation(s)
- Lionel Pintard
- Equipe labellisée Ligue contre le Cancer, Institut Jacques Monod, Team Cell Cycle and Development UMR7592, Centre National de la Recherche Scientifique - Université Paris Diderot, Sorbonne Paris Cité, 75013 Paris, France
| | - Bruce Bowerman
- Institute of Molecular Biology, University of Oregon, Eugene, OR 97403
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31
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Abstract
During cytokinesis, the cell employs various molecular machineries to separate into two daughters. Many signaling pathways are required to ensure temporal and spatial coordination of the molecular and mechanical events. Cells can also coordinate division with neighboring cells to maintain tissue integrity and flexibility. In this review, we focus on recent advances in the understanding of the molecular underpinnings of cytokinesis.
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Affiliation(s)
- Yinan Liu
- Departments of Cell Biology and Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
| | - Douglas Robinson
- Departments of Cell Biology and Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland, 21205, USA
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32
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Yang XM, Cao XY, He P, Li J, Feng MX, Zhang YL, Zhang XL, Wang YH, Yang Q, Zhu L, Nie HZ, Jiang SH, Tian GA, Zhang XX, Liu Q, Ji J, Zhu X, Xia Q, Zhang ZG. Overexpression of Rac GTPase Activating Protein 1 Contributes to Proliferation of Cancer Cells by Reducing Hippo Signaling to Promote Cytokinesis. Gastroenterology 2018; 155:1233-1249.e22. [PMID: 30009820 DOI: 10.1053/j.gastro.2018.07.010] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 06/26/2018] [Accepted: 07/03/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND & AIMS Agents designed to block or alter cytokinesis can kill or stop proliferation of cancer cells. We aimed to identify cytokinesis-related proteins that are overexpressed in hepatocellular carcinoma (HCC) cells and might be targeted to slow liver tumor growth. METHODS Using the Oncomine database, we compared the gene expression patterns in 16 cancer microarray datasets and assessed gene enrichment sets using gene ontology. We performed immunohistochemical analysis of an HCC tissue microarray and identified changes in protein levels that are associated with patient survival times. Candidate genes were overexpressed or knocked down with small hairpin RNAs in SMMC7721, MHCC97H, or HCCLM3 cell lines; we analyzed their proliferation, viability, and clone-formation ability and their growth as subcutaneous or orthotopic xenograft tumors in mice. We performed microarray analyses to identify alterations in signaling pathways and immunoblot and immunofluorescence assays to detect and localize proteins in tissues. Yeast 2-hybrid screens and mass spectrometry combined with co-immunoprecipitation experiments were used to identify binding proteins. Protein interactions were validated with co-immunoprecipitation and proximity ligation assays. Chromatin immunoprecipitation, promoter luciferase activity, and quantitative real-time polymerase chain reaction analyses were used to identify factors that regulate transcription of specific genes. RESULTS The genes that were most frequently overexpressed in different types of cancer cells were involved in cell division processes. We identified 3 cytokinesis-regulatory proteins among the 10 genes most frequently overexpressed by all cancer cell types. Rac GTPase activating protein 1 (RACGAP1) was the cytokinesis-regulatory protein that was most highly overexpressed in multiple cancers. Increased expression of RACGAP1 in tumor tissues was associated with shorter survival times of patients with cancer. Knockdown of RACGAP1 in HCC cells induced cytokinesis failure and cell apoptosis. In microarray analyses, we found knockdown of RACGAP1 in SMMC7721 cells to reduce expression of genes regulated by yes-associated protein (YAP) and WW domain containing transcription regulator 1 (WWTR1 or TAZ). RACGAP1 reduced activation of the Hippo pathway in HCC cells by increasing activity of RhoA and polymerization of filamentous actin. Knockdown of YAP reduced phosphorylation of RACGAP1 and redistribution at the anaphase central spindle. We found transcription of the translocated promoter region, nuclear basket protein (TPR) to be regulated by YAP and coordinately expressed with RACGAP1 to promote proliferation of HCC cells. TPR redistributed upon nuclear envelope breakdown and formed complexes with RACGAP1 during mitosis. Knockdown of TPR in HCC cells reduced phosphorylation of RACGAP1 by aurora kinase B and impaired their redistribution at the central spindle during cytokinesis. STAT3 activated transcription of RACGAP in HCC cells. CONCLUSIONS In an analysis of gene expression patterns of multiple tumor types, we found RACGAP1 to be frequently overexpressed, which is associated with shorter survival times of patients. RACGAP1 promotes proliferation of HCC cells by reducing activation of the Hippo and YAP pathways and promoting cytokinesis in coordination with TPR.
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Affiliation(s)
- Xiao-Mei Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Yan Cao
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ping He
- Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Jun Li
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ming-Xuan Feng
- Department of Liver Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Yan-Li Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xue-Li Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Ya-Hui Wang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qin Yang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Lei Zhu
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Hui-Zhen Nie
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Shu-Heng Jiang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Guang-Ang Tian
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Xiao-Xin Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Qiang Liu
- Department of Pathology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Jianguang Ji
- Center for Primary Health Care Research, Lund University Jan Waldenströms gata 35 Skåne University Hospital, Malmö, Sweden
| | - Xuefeng Zhu
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Qiang Xia
- Department of Liver Surgery, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
| | - Zhi-Gang Zhang
- State Key Laboratory of Oncogenes and Related Genes, Shanghai Cancer Institute, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China.
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33
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Zhang Z, Luo Z, Min W, Zhang L, Wu Y, Hu X. An anti-cancer WxxxE-containing azurin polypeptide inhibits Rac1-dependent STAT3 and ERK/GSK-3β signaling in breast cancer cells. Oncotarget 2018; 8:43091-43103. [PMID: 28549350 PMCID: PMC5522130 DOI: 10.18632/oncotarget.17759] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Accepted: 03/28/2017] [Indexed: 12/15/2022] Open
Abstract
In our previous study, we characterized a mycoplasmal small GTPase-like polypeptide of 240 amino acids that possesses an N-terminal WVLGE sequence. The N-terminal WVLGE sequence promotes activation of Rac1 and subsequent host cancer cell proliferation. To investigate the function of the WxxxE motif in the interaction with Rac1 and host tumor progression, we synthesized a 35-amino acid WVLGE-containing polypeptide derived from a cell-penetrating peptide derived from the azurin protein. We verified that the WVLGE-containing polypeptide targeted MCF-7 cells rather than MCF-10A cells. However, the WVLGE-containing polypeptide inhibited activation of Rac1 and induced cellular phenotypes that resulted from inhibition of Rac1. In addition, the WVLGE-containing polypeptide down-regulated phosphorylation of the STAT3 and ERK/GSK-3β signaling pathways, and this effect was abolished by either stimulation or inhibition of Rac1 activity. We also found that the WVLGE-containing polypeptide has a Rac1-dependent potential to suppress breast cancer growth in vitro and in vivo. We suggest that by acting as a Rac1 inhibitor, this novel polypeptide may be useful for the treatment of breast cancer.
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Affiliation(s)
- Zhe Zhang
- Department of Breast and Thyroid Surgery, Division of General Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Zhiyong Luo
- Department of Breast and Thyroid Surgery, Division of General Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Wenpu Min
- The First People's Hospital of Jingzhou, Jingzhou, People's Republic of China
| | - Lin Zhang
- Department of Breast and Thyroid Surgery, Division of General Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Yaqun Wu
- Department of Breast and Thyroid Surgery, Division of General Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
| | - Xiaopeng Hu
- Department of Breast and Thyroid Surgery, Division of General Surgery, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, People's Republic of China
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34
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Sartorel E, Ünlü C, Jose M, Massoni-Laporte A, Meca J, Sibarita JB, McCusker D. Phosphatidylserine and GTPase activation control Cdc42 nanoclustering to counter dissipative diffusion. Mol Biol Cell 2018; 29:1299-1310. [PMID: 29668348 PMCID: PMC5994902 DOI: 10.1091/mbc.e18-01-0051] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The anisotropic organization of plasma membrane constituents is indicative of mechanisms that drive the membrane away from equilibrium. However, defining these mechanisms is challenging due to the short spatiotemporal scales at which diffusion operates. Here, we use high-density single protein tracking combined with photoactivation localization microscopy (sptPALM) to monitor Cdc42 in budding yeast, a system in which Cdc42 exhibits anisotropic organization. Cdc42 exhibited reduced mobility at the cell pole, where it was organized in nanoclusters. The Cdc42 nanoclusters were larger at the cell pole than those observed elsewhere in the cell. These features were exacerbated in cells expressing Cdc42-GTP, and were dependent on the scaffold Bem1, which contributed to the range of mobility and nanocluster size exhibited by Cdc42. The lipid environment, in particular phosphatidylserine levels, also played a role in regulating Cdc42 nanoclustering. These studies reveal how the mobility of a Rho GTPase is controlled to counter the depletive effects of diffusion, thus stabilizing Cdc42 on the plasma membrane and sustaining cell polarity.
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Affiliation(s)
- Elodie Sartorel
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
| | - Caner Ünlü
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
| | - Mini Jose
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
| | - Aurélie Massoni-Laporte
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
| | - Julien Meca
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
| | - Jean-Baptiste Sibarita
- Université Bordeaux, Institut Interdisciplinaire de Neurosciences, Bordeaux 33077, France.,CNRS UMR 5297, Institut Interdisciplinaire de Neurosciences, Bordeaux 33077, France
| | - Derek McCusker
- Université Bordeaux, CNRS, UMR 5095, European Institute of Chemistry and Biology, Pessac 33607, France
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35
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Karayel Ö, Şanal E, Giese SH, Üretmen Kagıalı ZC, Polat AN, Hu CK, Renard BY, Tuncbag N, Özlü N. Comparative phosphoproteomic analysis reveals signaling networks regulating monopolar and bipolar cytokinesis. Sci Rep 2018; 8:2269. [PMID: 29396449 PMCID: PMC5797227 DOI: 10.1038/s41598-018-20231-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 01/05/2018] [Indexed: 01/21/2023] Open
Abstract
The successful completion of cytokinesis requires the coordinated activities of diverse cellular components including membranes, cytoskeletal elements and chromosomes that together form partly redundant pathways, depending on the cell type. The biochemical analysis of this process is challenging due to its dynamic and rapid nature. Here, we systematically compared monopolar and bipolar cytokinesis and demonstrated that monopolar cytokinesis is a good surrogate for cytokinesis and it is a well-suited system for global biochemical analysis in mammalian cells. Based on this, we established a phosphoproteomic signature of cytokinesis. More than 10,000 phosphorylation sites were systematically monitored; around 800 of those were up-regulated during cytokinesis. Reconstructing the kinase-substrate interaction network revealed 31 potentially active kinases during cytokinesis. The kinase-substrate network connects proteins between cytoskeleton, membrane and cell cycle machinery. We also found consensus motifs of phosphorylation sites that can serve as biochemical markers specific to cytokinesis. Beyond the kinase-substrate network, our reconstructed signaling network suggests that combination of sumoylation and phosphorylation may regulate monopolar cytokinesis specific signaling pathways. Our analysis provides a systematic approach to the comparison of different cytokinesis types to reveal alternative ways and a global overview, in which conserved genes work together and organize chromatin and cytoplasm during cytokinesis.
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Affiliation(s)
- Özge Karayel
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Erdem Şanal
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Sven H Giese
- Bioinformatics Division (MF1), Robert Koch Institute, Berlin, Germany
- Chair of Bioanalytics, Institute of Biotechnology, Technische Universität Berlin, Berlin, Germany
| | | | - Ayşe Nur Polat
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey
| | - Chi-Kuo Hu
- Department of Genetics, Stanford University, School of Medicine, CA, USA
| | - Bernhard Y Renard
- Bioinformatics Division (MF1), Robert Koch Institute, Berlin, Germany
| | - Nurcan Tuncbag
- Graduate School of Informatics, Department of Health Informatics, METU, Ankara, Turkey
- Cancer Systems Biology Laboratory (CanSyL), METU, Ankara, Turkey
| | - Nurhan Özlü
- Department of Molecular Biology and Genetics, Koç University, Istanbul, Turkey.
- Koç University Research Center for Translational Medicine (KUTTAM), Istanbul, Turkey.
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He X, Chen X, Li B, Ji J, Chen S. FAK inhibitors induce cell multinucleation and dramatically increase pro-tumoral cytokine expression in RAW 264.7 macrophages. FEBS Lett 2017; 591:3861-3871. [DOI: 10.1002/1873-3468.12895] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 10/12/2017] [Accepted: 10/18/2017] [Indexed: 12/20/2022]
Affiliation(s)
- Xia He
- Chengdu Institute of Biology; Chinese Academy of Sciences; Chengdu China
- University of Chinese Academy of Sciences; Beijing China
| | - Xin Chen
- Chengdu Institute of Biology; Chinese Academy of Sciences; Chengdu China
| | - Bogang Li
- Chengdu Institute of Biology; Chinese Academy of Sciences; Chengdu China
- Di Ao Pharmaceutical Group; Chengdu Sichuan China
| | - Jianxin Ji
- Chengdu Institute of Biology; Chinese Academy of Sciences; Chengdu China
| | - Shuang Chen
- Chengdu Institute of Biology; Chinese Academy of Sciences; Chengdu China
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Abstract
Cytokinesis in metazoan cells is mediated by an actomyosin-based contractile ring that assembles in response to activation of the small GTPase RhoA. The guanine nucleotide exchange factor that activates RhoA during cytokinesis, ECT-2, is highly regulated. In most metazoan cells, with the notable exception of the early
Caenorhabditis elegans embryo, RhoA activation and furrow ingression require the centralspindlin complex. This exception is due to the existence of a parallel pathway for RhoA activation in
C. elegans. Centralspindlin contains CYK-4 which contains a predicted Rho family GTPase-activating protein (GAP) domain. The function of this domain has been the subject of considerable debate. Some publications suggest that the GAP domain promotes RhoA activation (for example, Zhang and Glotzer, 2015; Loria, Longhini and Glotzer, 2012), whereas others suggest that it functions to inactivate the GTPase Rac1 (for example, Zhuravlev
et al., 2017). Here, we review the mechanisms underlying RhoA activation during cytokinesis, primarily focusing on data in
C. elegans. We highlight the importance of considering the parallel pathway for RhoA activation and detailed analyses of
cyk-4 mutant phenotypes when evaluating the role of the GAP domain of CYK-4.
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Affiliation(s)
| | - Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, Illinois, USA
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Breznau EB, Murt M, Blasius TL, Verhey KJ, Miller AL. The MgcRacGAP SxIP motif tethers Centralspindlin to microtubule plus ends in Xenopus laevis. J Cell Sci 2017; 130:1809-1821. [PMID: 28389580 DOI: 10.1242/jcs.195891] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 04/04/2017] [Indexed: 12/27/2022] Open
Abstract
Centralspindlin, a complex of the kinesin-6-family member MKLP1 and MgcRacGAP (also known as Kif23 and Racgap1, respectively), is required for cytokinesis and cell-cell junctions. During anaphase, Centralspindlin accumulates at overlapping central spindle microtubules and directs contractile ring formation by recruiting the GEF Ect2 to the cell equator to activate RhoA. We found that MgcRacGAP localized to the plus ends of equatorial astral microtubules during cytokinesis in Xenopus laevis embryos. How MgcRacGAP is stabilized at microtubule plus ends is unknown. We identified an SxIP motif in X. laevis MgcRacGAP that is conserved with other proteins that bind to EB1 (also known as Mapre1), a microtubule plus-end tracking protein. Mutation of the SxIP motif in MgcRacGAP resulted in loss of MgcRacGAP tracking with EB3 (also known as Mapre3) on growing microtubule plus ends, abnormal astral microtubule organization, redistribution of MgcRacGAP from the contractile ring to the polar cell cortex, and mislocalization of RhoA and its downstream targets, which together contributed to severe cytokinesis defects. Furthermore, mutation of the MgcRacGAP SxIP motif perturbed adherens junctions. We propose that the MgcRacGAP SxIP motif is functionally important both for its role in regulating adherens junction structure during interphase and for regulating Rho GTPase activity during cytokinesis.
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Affiliation(s)
- Elaina B Breznau
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Megan Murt
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - T Lynne Blasius
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Kristen J Verhey
- Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ann L Miller
- Program in Cellular and Molecular Biology, University of Michigan, Ann Arbor, MI 48109, USA .,Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA
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Zhuravlev Y, Hirsch SM, Jordan SN, Dumont J, Shirasu-Hiza M, Canman JC. CYK-4 regulates Rac, but not Rho, during cytokinesis. Mol Biol Cell 2017; 28:1258-1270. [PMID: 28298491 PMCID: PMC5415020 DOI: 10.1091/mbc.e17-01-0020] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Revised: 02/23/2017] [Accepted: 03/02/2017] [Indexed: 12/18/2022] Open
Abstract
The roles of the Rho-family GAP CYK-4 and small GTPase Rac during cytokinesis are examined in Caenorhabditis elegans embryos. CYK-4 opposes Rac (and potentially Cdc42) activity during cytokinesis. There is no evidence that CYK-4 is upstream of Rho activity or that Rac disruption is a general suppressor of cytokinesis failure. Cytokinesis is driven by constriction of an actomyosin contractile ring that is controlled by Rho-family small GTPases. Rho, activated by the guanine-nucleotide exchange factor ECT-2, is upstream of both myosin-II activation and diaphanous formin-mediated filamentous actin (f-actin) assembly, which drive ring constriction. The role for Rac and its regulators is more controversial, but, based on the finding that Rac inactivation can rescue cytokinesis failure when the GTPase-activating protein (GAP) CYK-4 is disrupted, Rac activity was proposed to be inhibitory to contractile ring constriction and thus specifically inactivated by CYK-4 at the division plane. An alternative model proposes that Rac inactivation generally rescues cytokinesis failure by reducing cortical tension, thus making it easier for the cell to divide when ring constriction is compromised. In this alternative model, CYK-4 was instead proposed to activate Rho by binding ECT-2. Using a combination of time-lapse in vivo single-cell analysis and Caenorhabditis elegans genetics, our evidence does not support this alternative model. First, we found that Rac disruption does not generally rescue cytokinesis failure: inhibition of Rac specifically rescues cytokinesis failure due to disruption of CYK-4 or ECT-2 but does not rescue cytokinesis failure due to disruption of two other contractile ring components, the Rho effectors diaphanous formin and myosin-II. Second, if CYK-4 regulates cytokinesis through Rho rather than Rac, then CYK-4 inhibition should decrease levels of downstream targets of Rho. Inconsistent with this, we found no change in the levels of f-actin or myosin-II at the division plane when CYK-4 GAP activity was reduced, suggesting that CYK-4 is not upstream of ECT-2/Rho activation. Instead, we found that the rescue of cytokinesis in CYK-4 mutants by Rac inactivation was Cdc42 dependent. Together our data suggest that CYK-4 GAP activity opposes Rac (and perhaps Cdc42) during cytokinesis.
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Affiliation(s)
- Yelena Zhuravlev
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032
| | - Sophia M Hirsch
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032
| | - Shawn N Jordan
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032
| | - Julien Dumont
- Institut Jacques Monod, CNRS, UMR 7592, Université Paris Diderot, Sorbonne Paris Cité, F-75205 Paris, France
| | - Mimi Shirasu-Hiza
- Department of Genetics and Development, Columbia University Medical Center, New York, NY 10032
| | - Julie C Canman
- Department of Pathology and Cell Biology, Columbia University Medical Center, New York, NY 10032
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Thieleke-Matos C, Osório DS, Carvalho AX, Morais-de-Sá E. Emerging Mechanisms and Roles for Asymmetric Cytokinesis. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2017; 332:297-345. [PMID: 28526136 DOI: 10.1016/bs.ircmb.2017.01.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Cytokinesis completes cell division by physically separating the contents of the mother cell between the two daughter cells. This event requires the highly coordinated reorganization of the cytoskeleton within a precise window of time to ensure faithful genomic segregation. In addition, recent progress in the field highlighted the importance of cytokinesis in providing particularly important cues in the context of multicellular tissues. The organization of the cytokinetic machinery and the asymmetric localization or inheritance of the midbody remnants is critical to define the spatial distribution of mechanical and biochemical signals. After a brief overview of the conserved steps of animal cytokinesis, we review the mechanisms controlling polarized cytokinesis focusing on the challenges of epithelial cytokinesis. Finally, we discuss the significance of these asymmetries in defining embryonic body axes, determining cell fate, and ensuring the correct propagation of epithelial organization during proliferation.
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Affiliation(s)
- C Thieleke-Matos
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cell Division and Genomic stability, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - D S Osório
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cytoskeletal Dynamics, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - A X Carvalho
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cytoskeletal Dynamics, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal
| | - E Morais-de-Sá
- i3S-Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal; Cell Division and Genomic stability, IBMC, Instituto de Biologia Molecular e Celular, and i3S, Instituto de Investigação e Inovação em Saúde, Universidade do Porto, Porto, Portugal.
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Kotýnková K, Su KC, West SC, Petronczki M. Plasma Membrane Association but Not Midzone Recruitment of RhoGEF ECT2 Is Essential for Cytokinesis. Cell Rep 2016; 17:2672-2686. [PMID: 27926870 PMCID: PMC5177604 DOI: 10.1016/j.celrep.2016.11.029] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2016] [Revised: 08/29/2016] [Accepted: 11/07/2016] [Indexed: 11/27/2022] Open
Abstract
Cytokinesis, the final step of cell division, begins with the formation of a cleavage furrow. How the mitotic spindle specifies the furrow at the equator in animal cells remains unknown. Current models propose that the concentration of the RhoGEF ECT2 at the spindle midzone and the equatorial plasma membrane directs furrow formation. Using chemical genetic and optogenetic tools, we demonstrate that the association of ECT2 with the plasma membrane during anaphase is required and sufficient for cytokinesis. Local membrane targeting of ECT2 leads to unilateral furrowing, highlighting the importance of local ECT2 activity. ECT2 mutations that prevent centralspindlin binding compromise concentration of ECT2 at the midzone and equatorial membrane but sustain cytokinesis. While the association of ECT2 with the plasma membrane is essential for cytokinesis, our data suggest that ECT2 recruitment to the spindle midzone is insufficient to account for equatorial furrowing and may act redundantly with yet-uncharacterized signals.
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Affiliation(s)
- Kristýna Kotýnková
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK; DNA Recombination and Repair Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Kuan-Chung Su
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK; Whitehead Institute and Department of Biology, MIT, 9 Cambridge Center, Cambridge, MA 02142, USA
| | - Stephen C West
- DNA Recombination and Repair Laboratory, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Mark Petronczki
- Cell Division and Aneuploidy Laboratory, Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK; Boehringer Ingelheim RCV, Dr.-Boehringer-Gasse 5-11, 1121 Vienna, Austria.
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Warga RM, Wicklund A, Webster SE, Kane DA. Progressive loss of RacGAP1/ ogre activity has sequential effects on cytokinesis and zebrafish development. Dev Biol 2016; 418:307-22. [PMID: 27339293 DOI: 10.1016/j.ydbio.2016.06.021] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2016] [Revised: 05/27/2016] [Accepted: 06/16/2016] [Indexed: 12/20/2022]
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Lawson CD, Der CJ. Filling GAPs in our knowledge: ARHGAP11A and RACGAP1 act as oncogenes in basal-like breast cancers. Small GTPases 2016; 9:290-296. [PMID: 27657701 DOI: 10.1080/21541248.2016.1220350] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023] Open
Abstract
Like RAS proteins, the aberrant function of RHO family small GTPases has been implicated in driving cancer development and growth. However, unlike the RAS family, where gain-of-function missense mutations are found in ∼25% of all human cancers, missense mutations are relatively rare in RHO proteins. Instead, altered RHO activity in cancer more commonly arises through the aberrant functions of RHO GTPase regulators. In many cancer types, altered expression and/or mutation of RHO-selective guanine nucleotide exchange factors (RHOGEFs) or GTPase-activating proteins (RHOGAPs), which activate or inactivate RHO GTPases, respectively, is observed. For example, deletion or loss of expression of the RHOA GAP DLC1 is well-established to drive cancer growth. Recently, we identified high expression of 2 RHOGAPs, ARHGAP11A and RACGAP1, in the basal-like breast cancer subtype. Unexpectedly, both of these RHOA GAPs exhibited properties of oncoproteins rather than tumor suppressors, in contrast to DLC1. In this commentary, we summarize our findings and speculate that different RHOA GAPs can play distinct roles in cancer depending on their spatial regulation and cancer type context. We also evaluate our results in light of recently-described cancer genome sequencing studies that have identified loss-of-function mutations of RHOA in specific cancer types.
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Affiliation(s)
- Campbell D Lawson
- a Randall Division of Cell and Molecular Biophysics, King's College London, New Hunt's House, Guy's Campus , London , UK
| | - Channing J Der
- b Department of Pharmacology and Lineberger Comprehensive Cancer Center , University of North Carolina at Chapel Hill , Chapel Hill , NC , USA
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44
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Abstract
Animal cells undergo dramatic changes in shape, mechanics and polarity as they progress through the different stages of cell division. These changes begin at mitotic entry, with cell-substrate adhesion remodelling, assembly of a cortical actomyosin network and osmotic swelling, which together enable cells to adopt a near spherical form even when growing in a crowded tissue environment. These shape changes, which probably aid spindle assembly and positioning, are then reversed at mitotic exit to restore the interphase cell morphology. Here, we discuss the dynamics, regulation and function of these processes, and how cell shape changes and sister chromatid segregation are coupled to ensure that the daughter cells generated through division receive their fair inheritance.
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45
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Lawson CD, Fan C, Mitin N, Baker NM, George SD, Graham DM, Perou CM, Burridge K, Der CJ, Rossman KL. Rho GTPase Transcriptome Analysis Reveals Oncogenic Roles for Rho GTPase-Activating Proteins in Basal-like Breast Cancers. Cancer Res 2016; 76:3826-37. [PMID: 27216196 DOI: 10.1158/0008-5472.can-15-2923] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 03/18/2016] [Indexed: 02/06/2023]
Abstract
The basal-like breast cancer (BLBC) subtype accounts for a disproportionately high percentage of overall breast cancer mortality. The current therapeutic options for BLBC need improvement; hence, elucidating signaling pathways that drive BLBC growth may identify novel targets for the development of effective therapies. Rho GTPases have previously been implicated in promoting tumor cell proliferation and metastasis. These proteins are inactivated by Rho-selective GTPase-activating proteins (RhoGAP), which have generally been presumed to act as tumor suppressors. Surprisingly, RNA-Seq analysis of the Rho GTPase signaling transcriptome revealed high expression of several RhoGAP genes in BLBC tumors, raising the possibility that these genes may be oncogenic. To evaluate this, we examined the roles of two of these RhoGAPs, ArhGAP11A (also known as MP-GAP) and RacGAP1 (also known as MgcRacGAP), in promoting BLBC. Both proteins were highly expressed in human BLBC cell lines, and knockdown of either gene resulted in significant defects in the proliferation of these cells. Knockdown of ArhGAP11A caused CDKN1B/p27-mediated arrest in the G1 phase of the cell cycle, whereas depletion of RacGAP1 inhibited growth through the combined effects of cytokinesis failure, CDKN1A/p21-mediated RB1 inhibition, and the onset of senescence. Random migration was suppressed or enhanced by the knockdown of ArhGAP11A or RacGAP1, respectively. Cell spreading and levels of GTP-bound RhoA were increased upon depletion of either RhoGAP. We have established that, via the suppression of RhoA, ArhGAP11A and RacGAP1 are both critical drivers of BLBC growth, and propose that RhoGAPs can act as oncogenes in cancer. Cancer Res; 76(13); 3826-37. ©2016 AACR.
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Affiliation(s)
- Campbell D Lawson
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Cheng Fan
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Natalia Mitin
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Nicole M Baker
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Samuel D George
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - David M Graham
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Charles M Perou
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Genetics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Keith Burridge
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Cell Biology and Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Channing J Der
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
| | - Kent L Rossman
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina. Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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46
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Mishima M. Centralspindlin in Rappaport’s cleavage signaling. Semin Cell Dev Biol 2016; 53:45-56. [DOI: 10.1016/j.semcdb.2016.03.006] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 03/02/2016] [Indexed: 02/07/2023]
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47
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Orii M, Kono K, Wen HI, Nakanishi M. PP1-Dependent Formin Bnr1 Dephosphorylation and Delocalization from a Cell Division Site. PLoS One 2016; 11:e0146941. [PMID: 26771880 PMCID: PMC4714816 DOI: 10.1371/journal.pone.0146941] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Accepted: 12/23/2015] [Indexed: 02/07/2023] Open
Abstract
Cell cycle ends with cytokinesis that is the physical separation of a cell into two daughter cells. For faithful cytokinesis, cells integrate multiple processes, such as actomyosin ring formation, contraction and plasma membrane closure, into coherent responses. Linear actin assembly by formins is essential for formation and maintenance of actomyosin ring. Although budding yeast’s two formins, Bni1 and Bnr1, are known to switch their subcellular localization at the division site prior to cytokinesis, the underlying mechanisms were not completely understood. Here, we provide evidence showing that Bnr1 is dephosphorylated concomitant with its release from the division site. Impaired PP1/Glc7 activity delayed Bnr1 release and dephosphorylation, Bni1 recruitment and actomyosin ring formation at the division site. These results suggest the involvement of Glc7 in this regulation. Further, we identified Ref2 as the PP1 regulatory subunit responsible for this regulation. Taken together, Glc7 and Ref2 may have a role in actomyosin ring formation by modulating the localization of formins during cytokinesis.
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Affiliation(s)
- Minami Orii
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
| | - Keiko Kono
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
- * E-mail: (MN); (KK)
| | - Hsin-I Wen
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
| | - Makoto Nakanishi
- Department of Cell Biology, Graduate School of Medical Sciences, Nagoya City University, 1 Kawasumi, Mizuho-cho, Mizuho-ku, Nagoya 467–8601, Japan
- * E-mail: (MN); (KK)
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van Adrichem AJ, Wennerberg K. MgcRacGAP inhibition stimulates JAK-dependent STAT3 activity. FEBS Lett 2015; 589:3859-65. [DOI: 10.1016/j.febslet.2015.11.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2015] [Revised: 10/26/2015] [Accepted: 11/11/2015] [Indexed: 10/22/2022]
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49
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van Adrichem AJ, Fagerholm A, Turunen L, Lehto A, Saarela J, Koskinen A, Repasky GA, Wennerberg K. Discovery of MINC1, a GTPase-activating protein small molecule inhibitor, targeting MgcRacGAP. Comb Chem High Throughput Screen 2015; 18:3-17. [PMID: 25479424 PMCID: PMC4435052 DOI: 10.2174/1386207318666141205112730] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2014] [Revised: 11/12/2014] [Accepted: 12/03/2014] [Indexed: 12/02/2022]
Abstract
The Rho family of Ras superfamily small GTPases regulates a broad range of biological processes such as migration, differentiation, cell growth and cell survival. Therefore, the availability of small molecule modulators as tool compounds could greatly enhance research on these proteins and their biological function. To this end, we designed a biochemical, high throughput screening assay with complementary follow-up assays to identify small molecule compounds inhibiting MgcRacGAP, a Rho family GTPase activating protein involved in cytokinesis and transcriptionally upregulated in many cancers. We first performed an in-house screen of 20,480 compounds, and later we tested the assay against 342,046 compounds from the NIH Molecular Libraries Small Molecule Repository. Primary screening hit rates were about 1% with the majority of those affecting the primary readout, an enzyme-coupled GDP detection assay. After orthogonal and counter screens, we identified two hits with high selectivity towards MgcRacGAP, compared with other RhoGAPs, and potencies in the low micromolar range. The most promising hit, termed MINC1, was then examined with cell-based testing where it was observed to induce an increased rate of cytokinetic failure and multinucleation in addition to other cell division defects, suggesting that it may act as an MgcRacGAP inhibitor also in cells.
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Affiliation(s)
| | | | | | | | | | | | | | - Krister Wennerberg
- Institute for Molecular Medicine Finland FIMM, Nordic EMBL Partnership for Molecular Medicine, Biomedicum Helsinki 2U, P.O. Box 20 (Tukholmankatu 8), FI- 00014, University of Helsinki, Finland.
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50
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Zhang D, Glotzer M. The RhoGAP activity of CYK-4/MgcRacGAP functions non-canonically by promoting RhoA activation during cytokinesis. eLife 2015; 4. [PMID: 26252513 PMCID: PMC4552957 DOI: 10.7554/elife.08898] [Citation(s) in RCA: 62] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 08/06/2015] [Indexed: 12/29/2022] Open
Abstract
Cytokinesis requires activation of the GTPase RhoA. ECT-2, the exchange factor responsible for RhoA activation, is regulated to ensure spatiotemporal control of contractile ring assembly. Centralspindlin, composed of the Rho family GTPase-activating protein (RhoGAP) MgcRacGAP/CYK-4 and the kinesin MKLP1/ZEN-4, is known to activate ECT-2, but the underlying mechanism is not understood. We report that ECT-2-mediated RhoA activation depends on the ability of CYK-4 to localize to the plasma membrane, bind RhoA, and promote GTP hydrolysis by RhoA. Defects resulting from loss of CYK-4 RhoGAP activity can be rescued by activating mutations in ECT-2 or depletion of RGA-3/4, which functions as a conventional RhoGAP for RhoA. Consistent with CYK-4 RhoGAP activity contributing to GEF activation, the catalytic domains of CYK-4 and ECT-2 directly interact. Thus, counterintuitively, CYK-4 RhoGAP activity promotes RhoA activation. We propose that the most active form of the cytokinetic RhoGEF involves complex formation between ECT-2, centralspindlin and RhoA. DOI:http://dx.doi.org/10.7554/eLife.08898.001 Cell division is a process in which a cell splits to form two daughter cells. In most cases, the cell first duplicates its genetic material and then the two copies are pulled to opposite ends of the cell. A ring of protein filaments—called the contractile ring—then assembles to form a band around the cell at the site of the division. This ring contracts and the force generated separates the cells in a step known as cytokinesis. A protein belonging to the Rho family, called RhoA, is essential for cytokinesis because it controls the formation of the contractile ring. Rho proteins are switched on by the activities of other proteins called guanine nucleotide exchange factors. Another group of proteins known as ‘GTPase activating proteins’ (or GAPs for short) generally act to promote the ability of Rho proteins to turn themselves off. In animals and other multicellular organisms, a GAP called CYK-4 largely concentrates on the spindle midzone, but some of the protein also moves to part of the cell membrane near the future site of cell division. It binds to a guanine nucleotide exchange factor called ECT-2 to switch RhoA on, which in turn promotes the formation of the contractile ring. However, it is not clear why a protein that activates RhoA is also able to trigger its inactivation. In this study, Zhang and Glotzer studied cell division in a roundworm called Caenorhabditis elegans. The experiments show that cells that lacked the GAP activity of CYK-4 were unable to complete cytokinesis because RhoA was not fully switched on. This requirement could be bypassed in cells with mutant forms of ECT-2 that were overactive. Therefore, an activity that was thought to inactivate RhoA actually promotes its activation. Further experiments show that the section (or ‘domain’) of CYK-4 that has GAP activity interacts directly with the guanine nucleotide exchange domain of ECT2. Zhang and Glotzer suggest that this interaction stimulates ECT2 and thereby promotes the activation of RhoA. Further experiments will reveal how CYK-4 stimulates ECT-2. In addition, it will be important to determine whether other proteins with GAP domains also work in this unconventional way. DOI:http://dx.doi.org/10.7554/eLife.08898.002
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Affiliation(s)
- Donglei Zhang
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States
| | - Michael Glotzer
- Department of Molecular Genetics and Cell Biology, University of Chicago, Chicago, United States
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