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Pushpa K, Dagar S, Kumar H, Pathak D, Mylavarapu SVS. The exocyst complex regulates C. elegans germline stem cell proliferation by controlling membrane Notch levels. Development 2021; 148:271155. [PMID: 34338279 DOI: 10.1242/dev.196345] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2020] [Accepted: 06/30/2021] [Indexed: 11/20/2022]
Abstract
The conserved exocyst complex regulates plasma membrane-directed vesicle fusion in eukaryotes. However, its role in stem cell proliferation has not been reported. Germline stem cell (GSC) proliferation in the nematode Caenorhabditis elegans is regulated by conserved Notch signaling. Here, we reveal that the exocyst complex regulates C. elegans GSC proliferation by modulating Notch signaling cell autonomously. Notch membrane density is asymmetrically maintained on GSCs. Knockdown of exocyst complex subunits or of the exocyst-interacting GTPases Rab5 and Rab11 leads to Notch redistribution from the GSC-niche interface to the cytoplasm, suggesting defects in plasma membrane Notch deposition. The anterior polarity (aPar) protein Par6 is required for GSC proliferation, and for maintaining niche-facing membrane levels of Notch and the exocyst complex. The exocyst complex biochemically interacts with the aPar regulator Par5 (14-3-3ζ) and Notch in C. elegans and human cells. Exocyst components are required for Notch plasma membrane localization and signaling in mammalian cells. Our study uncovers a possibly conserved requirement of the exocyst complex in regulating GSC proliferation and in maintaining optimal membrane Notch levels.
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Affiliation(s)
- Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sunayana Dagar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India
| | - Harsh Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Diksha Pathak
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India.,Kalinga Institute of Industrial Technology, Bhubaneswar, Odisha 751024, India.,Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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Osawa Y, Murata K, Usui M, Kuba Y, Le HT, Mikami N, Nakagawa T, Daitoku Y, Kato K, Shawki HH, Ikeda Y, Kuno A, Morimoto K, Tanimoto Y, Dinh TTH, Yagami KI, Ema M, Yoshida S, Takahashi S, Mizuno S, Sugiyama F. EXOC1 plays an integral role in spermatogonia pseudopod elongation and spermatocyte stable syncytium formation in mice. eLife 2021; 10:59759. [PMID: 33973520 PMCID: PMC8112867 DOI: 10.7554/elife.59759] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Accepted: 04/21/2021] [Indexed: 11/13/2022] Open
Abstract
The male germ cells must adopt the correct morphology at each differentiation stage for proper spermatogenesis. The spermatogonia regulates its differentiation state by its own migration. The male germ cells differentiate and mature with the formation of syncytia, failure of forming the appropriate syncytia results in the arrest at the spermatocyte stage. However, the detailed molecular mechanisms of male germ cell morphological regulation are unknown. Here, we found that EXOC1, a member of the Exocyst complex, is important for the pseudopod formation of spermatogonia and spermatocyte syncytia in mice. EXOC1 contributes to the pseudopod formation of spermatogonia by inactivating the Rho family small GTPase Rac1 and also functions in the spermatocyte syncytia with the SNARE proteins STX2 and SNAP23. Since EXOC1 is known to bind to several cell morphogenesis factors, this study is expected to be the starting point for the discovery of many morphological regulators of male germ cells.
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Affiliation(s)
- Yuki Osawa
- Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Kazuya Murata
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Miho Usui
- School of Medical Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yumeno Kuba
- Master's Program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Hoai Thu Le
- Ph.D Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Japan
| | - Natsuki Mikami
- Ph.D Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Japan
| | - Toshinori Nakagawa
- Division of Germ Cell Biology, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan.,Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies (Sokendai), Okazaki, Japan
| | - Yoko Daitoku
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Kanako Kato
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Hossam Hassan Shawki
- Department of Comparative and Experimental Medicine, Nagoya City University Graduate School of Medical Sciences, Nagoya, Japan
| | - Yoshihisa Ikeda
- Doctoral program in Biomedical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Akihiro Kuno
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan.,Ph.D Program in Human Biology, School of Integrative and Global Majors, University of Tsukuba, Tsukuba, Japan
| | - Kento Morimoto
- Doctoral program in Medical Sciences, Graduate School of Comprehensive Human Sciences, University of Tsukuba, Tsukuba, Japan
| | - Yoko Tanimoto
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Tra Thi Huong Dinh
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Ken-Ichi Yagami
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Masatsugu Ema
- Department of Stem Cells and Human Disease Models, Research Center for Animal Life Science, Shiga University of Medical Science, Otsu, Japan
| | - Shosei Yoshida
- Division of Germ Cell Biology, National Institute for Basic Biology, National Institutes of Natural Sciences, Okazaki, Japan.,Department of Basic Biology, School of Life Science, Graduate University for Advanced Studies (Sokendai), Okazaki, Japan
| | - Satoru Takahashi
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Seiya Mizuno
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
| | - Fumihiro Sugiyama
- Laboratory Animal Resource Center, Trans-border Medical Research Center, University of Tsukuba, Tsukuba, Japan
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3
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Van Bergen NJ, Ahmed SM, Collins F, Cowley M, Vetro A, Dale RC, Hock DH, de Caestecker C, Menezes M, Massey S, Ho G, Pisano T, Glover S, Gusman J, Stroud DA, Dinger M, Guerrini R, Macara IG, Christodoulou J. Mutations in the exocyst component EXOC2 cause severe defects in human brain development. J Exp Med 2021; 217:151928. [PMID: 32639540 PMCID: PMC7537385 DOI: 10.1084/jem.20192040] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2019] [Revised: 02/03/2020] [Accepted: 04/03/2020] [Indexed: 12/30/2022] Open
Abstract
The exocyst, an octameric protein complex, is an essential component of the membrane transport machinery required for tethering and fusion of vesicles at the plasma membrane. We report pathogenic variants in an exocyst subunit, EXOC2 (Sec5). Affected individuals have severe developmental delay, dysmorphism, and brain abnormalities; variability associated with epilepsy; and poor motor skills. Family 1 had two offspring with a homozygous truncating variant in EXOC2 that leads to nonsense-mediated decay of EXOC2 transcript, a severe reduction in exocytosis and vesicle fusion, and undetectable levels of EXOC2 protein. The patient from Family 2 had a milder clinical phenotype and reduced exocytosis. Cells from both patients showed defective Arl13b localization to the primary cilium. The discovery of mutations that partially disable exocyst function provides valuable insight into this essential protein complex in neural development. Since EXOC2 and other exocyst complex subunits are critical to neuronal function, our findings suggest that EXOC2 variants are the cause of the patients’ neurological disorders.
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Affiliation(s)
- Nicole J Van Bergen
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Syed Mukhtar Ahmed
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Felicity Collins
- Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Medical Genomics Department, Royal Prince Alfred Hospital, Sydney, New South Wales, Australia
| | - Mark Cowley
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,St Vincent's Clinical School, University of New South Wales Sydney, Sydney, New South Wales, Australia.,Children's Cancer Institute, Kensington, New South Wales, Australia
| | - Annalisa Vetro
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Russell C Dale
- Department of Paediatric Neurology, The Children's Hospital at Westmead, Sydney, New South Wales, Australia.,Kids Neuroscience Centre, Faculty of Medicine and Health, The University of Sydney, Sydney, New South Wales, Australia
| | - Daniella H Hock
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Christian de Caestecker
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - Minal Menezes
- Kids Research, The Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Sean Massey
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia
| | - Gladys Ho
- Western Sydney Genetics Program, Children's Hospital at Westmead, Sydney, New South Wales, Australia
| | - Tiziana Pisano
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Seana Glover
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - Jovanka Gusman
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia
| | - David A Stroud
- Department of Biochemistry and Molecular Biology and The Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Parkville, Victoria, Australia
| | - Marcel Dinger
- Kinghorn Centre for Clinical Genomics, Garvan Institute of Medical Research, Sydney, New South Wales, Australia.,School of Biotechnology and Biomolecular Sciences, University of New South Wales, Kensington Campus, Sydney, New South Wales, Australia
| | - Renzo Guerrini
- Pediatric Neurology, Neurogenetics and Neurobiology Unit and Laboratories, Meyer Children's Hospital, University of Florence, Florence, Italy
| | - Ian G Macara
- Department of Cell and Developmental Biology, Vanderbilt University School of Medicine, Nashville, TN
| | - John Christodoulou
- Brain and Mitochondrial Research Group, Murdoch Children's Research Institute, Royal Children's Hospital, Melbourne, Victoria, Australia.,Department of Paediatrics, University of Melbourne, Melbourne, Victoria, Australia.,Victorian Clinical Genetics Services, Royal Children's Hospital, Parkville, Victoria, Australia
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