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Bruna-Gauchoux J, Montagnac G. Constraints and frustration in the clathrin-dependent endocytosis pathway. C R Biol 2022; 345:43-56. [PMID: 36847464 DOI: 10.5802/crbiol.88] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 09/05/2022] [Indexed: 11/24/2022]
Abstract
Clathrin-dependent endocytosis is the major pathway for the entry of most surface receptors and their ligands. It is controlled by clathrin-coated structures that are endowed with the ability to cluster receptors and locally bend the plasma membrane, leading to the formation of receptor-containing vesicles budding into the cytoplasm. This canonical role of clathrin-coated structures has been repeatedly demonstrated to play a fundamental role in a wide range of aspects of cell physiology. However, it is now clearly established that the ability of clathrin-coated structures to bend the membrane can be disrupted. In addition to chemical or genetic alterations, many environmental conditions can physically prevent or slow membrane deformation and/or budding of clathrin-coated structures. The resulting frustrated endocytosis is not only a passive consequence but serves very specific and important cellular functions. Here we provide a historical perspective as well as a definition of frustrated endocytosis in the clathrin pathway before describing its causes and many functional consequences.
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2
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Cheng J, Liu Z, Deng T, Lu Z, Liu M, Lu X, Adeshakin FO, Yan D, Zhang G, Wan X. CD317 mediates immunocytolysis resistance by RICH2/cytoskeleton-dependent membrane protection. Mol Immunol 2020; 129:94-102. [PMID: 33223223 DOI: 10.1016/j.molimm.2020.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 10/20/2020] [Accepted: 11/04/2020] [Indexed: 11/19/2022]
Abstract
Immune evasion is a common hallmark of cancers. Immunotherapies that aim at restoring or increasing the immune response against cancers have revolutionized outcomes for patients, but the mechanisms of resistance remain poorly defined. Here, we report that CD317, a surface molecule with a unique topology that is double anchored into the membrane, protects tumor cells from immunocytolysis. CD317 knockdown in tumor cells renders more severe death in response to NK or chimeric antigen receptor-modified NK cells challenge. Such effects of CD317 silencing might be the results of increasing sensitivity of tumor cells to immune killing rather than strengthening immune response, since neither effector-target cell contact nor the activation of effector cells was affected, and the enhanced cytolysis was also not counteracted by the addition of recombinant CD317 proteins. Mechanistically, CD317 might endow tumor cells with more flexibility to modulate cytoskeleton through its association with RICH2, thereby protects membrane integrity against perforin and consequently promotes survival in response to immunocytolysis. These results reveal a new mechanism of immunocytolysis resistance and suggest CD317 as an attractive target which can be exploited for improving the efficacy of cancer immunotherapies.
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Affiliation(s)
- Jian Cheng
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China
| | - Zhao Liu
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China
| | - Tian Deng
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China
| | - Zhen Lu
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Maoxuan Liu
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China
| | - Xiaoxu Lu
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Funmilayo Oladunni Adeshakin
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; University of Chinese Academy of Sciences, Beijing, 100049, PR China
| | - Dehong Yan
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China
| | - Guizhong Zhang
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China.
| | - Xiaochun Wan
- Center for Protein and Cell-based Drugs, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, PR China; Guangdong immune cell therapy engineering and technology research center (No. 2580 [2018]), PR China; Shenzhen BinDeBioTech Co., Ltd., Floor 5, Building 6, Tongfuyu Industrial City, Xili, Nanshan, Shenzhen, 518055, PR China.
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3
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Bajur AT, Iyer KV, Knust E. Cytocortex-dependent dynamics of Drosophila Crumbs controls junctional stability and tension during germ band retraction. J Cell Sci 2019; 132:jcs.228338. [PMID: 31300472 DOI: 10.1242/jcs.228338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 07/05/2019] [Indexed: 12/21/2022] Open
Abstract
During morphogenesis, epithelia undergo dynamic rearrangements, which requires continuous remodelling of junctions and cell shape, but at the same time mechanisms preserving cell polarity and tissue integrity. Apico-basal polarity is key for the localisation of the machinery that enables cell shape changes. The evolutionarily conserved Drosophila Crumbs protein is critical for maintaining apico-basal polarity and epithelial integrity. How Crumbs is maintained in a dynamically developing embryo remains largely unknown. Here, we applied quantitative fluorescence techniques to show that, during germ band retraction, Crumbs dynamics correlates with the morphogenetic activity of the epithelium. Genetic and pharmacological perturbations revealed that the mobile pool of Crumbs is fine-tuned by the actomyosin cortex in a stage-dependent manner. Stabilisation of Crumbs at the plasma membrane depends on a proper link to the actomyosin cortex via an intact FERM-domain-binding site in its intracellular domain, loss of which leads to increased junctional tension and higher DE-cadherin (also known as Shotgun) turnover, resulting in impaired junctional rearrangements. These data define Crumbs as a mediator between polarity and junctional regulation to orchestrate epithelial remodelling in response to changes in actomyosin activity.This article has an associated First Person interview with the first author of the paper.
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Affiliation(s)
- Anna T Bajur
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - K Venkatesan Iyer
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
| | - Elisabeth Knust
- Max-Planck Institute of Molecular Cell Biology and Genetics, 01307 Dresden, Germany
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4
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Spracklen AJ, Thornton-Kolbe EM, Bonner AN, Florea A, Compton PJ, Fernandez-Gonzalez R, Peifer M. The Crk adapter protein is essential for Drosophila embryogenesis, where it regulates multiple actin-dependent morphogenic events. Mol Biol Cell 2019; 30:2399-2421. [PMID: 31318326 PMCID: PMC6741062 DOI: 10.1091/mbc.e19-05-0302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Small Src homology domain 2 (SH2) and 3 (SH3) adapter proteins regulate cell fate and behavior by mediating interactions between cell surface receptors and downstream signaling effectors in many signal transduction pathways. The CT10 regulator of kinase (Crk) family has tissue-specific roles in phagocytosis, cell migration, and neuronal development and mediates oncogenic signaling in pathways like that of Abelson kinase. However, redundancy among the two mammalian family members and the position of the Drosophila gene on the fourth chromosome precluded assessment of Crk's full role in embryogenesis. We circumvented these limitations with short hairpin RNA and CRISPR technology to assess Crk's function in Drosophila morphogenesis. We found that Crk is essential beginning in the first few hours of development, where it ensures accurate mitosis by regulating orchestrated dynamics of the actin cytoskeleton to keep mitotic spindles in syncytial embryos from colliding. In this role, it positively regulates cortical localization of the actin-related protein 2/3 complex (Arp2/3), its regulator suppressor of cAMP receptor (SCAR), and filamentous actin to actin caps and pseudocleavage furrows. Crk loss leads to the loss of nuclei and formation of multinucleate cells. We also found roles for Crk in embryonic wound healing and in axon patterning in the nervous system, where it localizes to the axons and midline glia. Thus, Crk regulates diverse events in embryogenesis that require orchestrated cytoskeletal dynamics.
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Affiliation(s)
- Andrew J Spracklen
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Emma M Thornton-Kolbe
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alison N Bonner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Alexandru Florea
- Institute of Biomaterials and Biomedical Engineering, Ted Rogers Centre for Heart Research, and Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Peter J Compton
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
| | - Rodrigo Fernandez-Gonzalez
- Institute of Biomaterials and Biomedical Engineering, Ted Rogers Centre for Heart Research, and Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Mark Peifer
- Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599.,Curriculum in Genetics and Molecular Biology, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599
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5
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Abstract
The first 3 h of Drosophila melanogaster embryo development are exemplified by rapid nuclear divisions within a large syncytium, transforming the zygote to the cellular blastoderm after 13 successive cleavage divisions. As the syncytial embryo develops, it relies on centrosomes and cytoskeletal dynamics to transport nuclei, maintain uniform nuclear distribution throughout cleavage cycles, ensure generation of germ cells, and coordinate cellularization. For the sake of this review, we classify six early embryo stages that rely on processes coordinated by the centrosome and its regulation of the cytoskeleton. The first stage features migration of one of the female pronuclei toward the male pronucleus following maturation of the first embryonic centrosomes. Two subsequent stages distribute the nuclei first axially and then radially in the embryo. The remaining three stages involve centrosome-actin dynamics that control cortical plasma membrane morphogenesis. In this review, we highlight the dynamics of the centrosome and its role in controlling the six stages that culminate in the cellularization of the blastoderm embryo.
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Affiliation(s)
- Caitlyn Blake-Hedges
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA.
| | - Timothy L Megraw
- Department of Biomedical Sciences, College of Medicine, Florida State University, Tallahassee, FL, USA
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6
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Figard L, Wang M, Zheng L, Golding I, Sokac AM. Membrane Supply and Demand Regulates F-Actin in a Cell Surface Reservoir. Dev Cell 2017; 37:267-78. [PMID: 27165556 DOI: 10.1016/j.devcel.2016.04.010] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 11/19/2015] [Accepted: 04/12/2016] [Indexed: 11/16/2022]
Abstract
Cells store membrane in surface reservoirs of pits and protrusions. These membrane reservoirs facilitate cell shape change and buffer mechanical stress, but we do not know how reservoir dynamics are regulated. During cellularization, the first cytokinesis in Drosophila embryos, a reservoir of microvilli unfolds to fuel cleavage furrow ingression. We find that regulated exocytosis adds membrane to the reservoir before and during unfolding. Dynamic F-actin deforms exocytosed membrane into microvilli. Single microvilli extend and retract in ∼20 s, while the overall reservoir is depleted in sync with furrow ingression over 60-70 min. Using pharmacological and genetic perturbations, we show that exocytosis promotes microvillar F-actin assembly, while furrow ingression controls microvillar F-actin disassembly. Thus, reservoir F-actin and, consequently, reservoir dynamics are regulated by membrane supply from exocytosis and membrane demand from furrow ingression.
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Affiliation(s)
- Lauren Figard
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA
| | - Mengyu Wang
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA
| | - Liuliu Zheng
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA
| | - Ido Golding
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Structural and Computational Biology and Molecular Biophysics, Baylor College of Medicine, Houston, TX 77030, USA; Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA; Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA
| | - Anna Marie Sokac
- Verna & Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, BCM125, Houston, TX 77030, USA; Graduate Program in Integrative Molecular and Biomedical Sciences, Baylor College of Medicine, Houston, TX 77030, USA.
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Abstract
Although biosynthetic trafficking can function constitutively, it also functions specifically for certain developmental processes. These processes require either a large increase to biosynthesis or the biosynthesis and targeted trafficking of specific players. We review the conserved molecular mechanisms that direct biosynthetic trafficking, and discuss how their genetic disruption affects animal development. Specifically, we consider Arf small G proteins, such as Arf1 and Sar1, and their coat effectors, COPI and COPII, and how these proteins promote biosynthetic trafficking for cleavage of the Drosophila embryo, the growth of neuronal dendrites and synapses, extracellular matrix secretion for bone development, lumen development in epithelial tubes, notochord and neural tube development, and ciliogenesis. Specific need for the biosynthetic trafficking system is also evident from conserved CrebA/Creb3-like transcription factors increasing the expression of secretory machinery during several of these developmental processes. Moreover, dysfunctional trafficking leads to a range of developmental syndromes.
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Affiliation(s)
- Francisco F Rodrigues
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
| | - Tony J C Harris
- Department of Cell & Systems Biology, University of Toronto , Toronto , Ontario , Canada
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8
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Fujita N, Huang W, Lin TH, Groulx JF, Jean S, Nguyen J, Kuchitsu Y, Koyama-Honda I, Mizushima N, Fukuda M, Kiger AA. Genetic screen in Drosophila muscle identifies autophagy-mediated T-tubule remodeling and a Rab2 role in autophagy. eLife 2017; 6. [PMID: 28063257 PMCID: PMC5249261 DOI: 10.7554/elife.23367] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/17/2016] [Indexed: 01/04/2023] Open
Abstract
Transverse (T)-tubules make-up a specialized network of tubulated muscle cell membranes involved in excitation-contraction coupling for power of contraction. Little is known about how T-tubules maintain highly organized structures and contacts throughout the contractile system despite the ongoing muscle remodeling that occurs with muscle atrophy, damage and aging. We uncovered an essential role for autophagy in T-tubule remodeling with genetic screens of a developmentally regulated remodeling program in Drosophila abdominal muscles. Here, we show that autophagy is both upregulated with and required for progression through T-tubule disassembly stages. Along with known mediators of autophagosome-lysosome fusion, our screens uncovered an unexpected shared role for Rab2 with a broadly conserved function in autophagic clearance. Rab2 localizes to autophagosomes and binds to HOPS complex members, suggesting a direct role in autophagosome tethering/fusion. Together, the high membrane flux with muscle remodeling permits unprecedented analysis both of T-tubule dynamics and fundamental trafficking mechanisms. DOI:http://dx.doi.org/10.7554/eLife.23367.001
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Affiliation(s)
- Naonobu Fujita
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States.,Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Wilson Huang
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Tzu-Han Lin
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jean-Francois Groulx
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Steve Jean
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Jen Nguyen
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
| | - Yoshihiko Kuchitsu
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Ikuko Koyama-Honda
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Noboru Mizushima
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Mitsunori Fukuda
- Laboratory of Membrane Trafficking Mechanisms, Department of Developmental Biology and Neurosciences, Graduate School of Life Sciences, Tohoku University, Sendai, Japan
| | - Amy A Kiger
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, United States
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9
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Rodrigues FF, Shao W, Harris TJC. The Arf GAP Asap promotes Arf1 function at the Golgi for cleavage furrow biosynthesis in Drosophila. Mol Biol Cell 2016; 27:3143-3155. [PMID: 27535433 PMCID: PMC5063621 DOI: 10.1091/mbc.e16-05-0272] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2016] [Accepted: 08/11/2016] [Indexed: 11/11/2022] Open
Abstract
Drosophila embryo cleavage requires the conserved Arf GAP Asap. Asap seems to recycle Arf1 to the Golgi from post-Golgi membranes for optimal Golgi output and cleavage furrow biosynthesis. Biosynthetic traffic from the Golgi drives plasma membrane growth. For Drosophila embryo cleavage, this growth is rapid but regulated for cycles of furrow ingression and regression. The highly conserved small G protein Arf1 organizes Golgi trafficking. Arf1 is activated by guanine nucleotide exchange factors, but essential roles for Arf1 GTPase-activating proteins (GAPs) are less clear. We report that the conserved Arf GAP Asap is required for cleavage furrow ingression in the early embryo. Because Asap can affect multiple subcellular processes, we used genetic approaches to dissect its primary effect. Our data argue against cytoskeletal or endocytic involvement and reveal a common role for Asap and Arf1 in Golgi organization. Although Asap lacked Golgi enrichment, it was necessary and sufficient for Arf1 accumulation at the Golgi, and a conserved Arf1-Asap binding site was required for Golgi organization and output. Of note, Asap relocalized to the nuclear region at metaphase, a shift that coincided with subtle Golgi reorganization preceding cleavage furrow regression. We conclude that Asap is essential for Arf1 to function at the Golgi for cleavage furrow biosynthesis. Asap may recycle Arf1 to the Golgi from post-Golgi membranes, providing optimal Golgi output for specific stages of the cell cycle.
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Affiliation(s)
- Francisco F Rodrigues
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Wei Shao
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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10
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Paulissen SM, Slubowski CJ, Roesner JM, Huang LS. Timely Closure of the Prospore Membrane Requires SPS1 and SPO77 in Saccharomyces cerevisiae. Genetics 2016; 203:1203-16. [PMID: 27182947 DOI: 10.1534/genetics.115.183939] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Accepted: 05/09/2016] [Indexed: 11/18/2022] Open
Abstract
During sporulation in Saccharomyces cerevisiae, a double lipid bilayer called the prospore membrane is formed de novo, growing around each meiotic nucleus and ultimately closing to create four new cells within the mother cell. Here we show that SPS1, which encodes a kinase belonging to the germinal center kinase III family, is involved in prospore membrane development and is required for prospore membrane closure. We find that SPS1 genetically interacts with SPO77 and see that loss of either gene disrupts prospore membrane closure in a similar fashion. Specifically, cells lacking SPS1 and SPO77 produce hyperelongated prospore membranes from which the leading edge protein complex is not removed from the prospore membrane in a timely fashion. The SPS1/SPO77 pathway is required for the proper phosphorylation and stability of Ssp1, a member of the leading edge protein complex that is removed and degraded when the prospore membrane closes. Genetic dissection of prospore membrane closure finds SPS1 and SPO77 act in parallel to a previously described pathway of prospore membrane closure that involves AMA1, an activator of the meiotic anaphase promoting complex.
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11
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Lee DM, Rodrigues FF, Yu CG, Swan M, Harris TJC. PH Domain-Arf G Protein Interactions Localize the Arf-GEF Steppke for Cleavage Furrow Regulation in Drosophila. PLoS One 2015; 10:e0142562. [PMID: 26556630 PMCID: PMC4640550 DOI: 10.1371/journal.pone.0142562] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Accepted: 10/23/2015] [Indexed: 11/18/2022] Open
Abstract
The recruitment of GDP/GTP exchange factors (GEFs) to specific subcellular sites dictates where they activate small G proteins for the regulation of various cellular processes. Cytohesins are a conserved family of plasma membrane GEFs for Arf small G proteins that regulate endocytosis. Analyses of mammalian cytohesins have identified a number of recruitment mechanisms for these multi-domain proteins, but the conservation and developmental roles for these mechanisms are unclear. Here, we report how the pleckstrin homology (PH) domain of the Drosophila cytohesin Steppke affects its localization and activity at cleavage furrows of the early embryo. We found that the PH domain is necessary for Steppke furrow localization, and for it to regulate furrow structure. However, the PH domain was not sufficient for the localization. Next, we examined the role of conserved PH domain amino acid residues that are required for mammalian cytohesins to bind PIP3 or GTP-bound Arf G proteins. We confirmed that the Steppke PH domain preferentially binds PIP3 in vitro through a conserved mechanism. However, disruption of residues for PIP3 binding had no apparent effect on GFP-Steppke localization and effects. Rather, residues for binding to GTP-bound Arf G proteins made major contributions to this Steppke localization and activity. By analyzing GFP-tagged Arf and Arf-like small G proteins, we found that Arf1-GFP, Arf6-GFP and Arl4-GFP, but not Arf4-GFP, localized to furrows. However, analyses of embryos depleted of Arf1, Arf6 or Arl4 revealed either earlier defects than occur in embryos depleted of Steppke, or no detectable furrow defects, possibly because of redundancies, and thus it was difficult to assess how individual Arf small G proteins affect Steppke. Nonetheless, our data show that the Steppke PH domain and its conserved residues for binding to GTP-bound Arf G proteins have substantial effects on Steppke localization and activity in early Drosophila embryos.
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Affiliation(s)
- Donghoon M. Lee
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | | | - Cao Guo Yu
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Michael Swan
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
| | - Tony J. C. Harris
- Department of Cell & Systems Biology, University of Toronto, Toronto, Ontario, Canada
- * E-mail:
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12
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Kumar M, Pushpa K, Mylavarapu SVS. Splitting the cell, building the organism: Mechanisms of cell division in metazoan embryos. IUBMB Life 2015; 67:575-87. [PMID: 26173082 PMCID: PMC5937677 DOI: 10.1002/iub.1404] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2015] [Accepted: 06/18/2015] [Indexed: 11/12/2022]
Abstract
The unicellular metazoan zygote undergoes a series of cell divisions that are central to its development into an embryo. Differentiation of embryonic cells leads eventually to the development of a functional adult. Fate specification of pluripotent embryonic cells occurs during the early embryonic cleavage divisions in several animals. Early development is characterized by well-known stages of embryogenesis documented across animals--morulation, blastulation, and morphogenetic processes such as gastrulation, all of which contribute to differentiation and tissue specification. Despite this broad conservation, there exist clearly discernible morphological and functional differences across early embryonic stages in metazoans. Variations in the mitotic mechanisms of early embryonic cell divisions play key roles in governing these gross differences that eventually encode developmental patterns. In this review, we discuss molecular mechanisms of both karyokinesis (nuclear division) and cytokinesis (cytoplasmic separation) during early embryonic divisions. We outline the broadly conserved molecular pathways that operate in these two stages in early embryonic mitoses. In addition, we highlight mechanistic variations in these two stages across different organisms. We finally discuss outstanding questions of interest, answers to which would illuminate the role of divergent mitotic mechanisms in shaping early animal embryogenesis.
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Affiliation(s)
- Megha Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, India
| | - Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, India
| | - Sivaram V. S. Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, Faridabad, Haryana, India
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13
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Liu J, Lee DM, Yu CG, Angers S, Harris TJC. Stepping stone: a cytohesin adaptor for membrane cytoskeleton restraint in the syncytial Drosophila embryo. Mol Biol Cell 2014; 26:711-25. [PMID: 25540427 PMCID: PMC4325841 DOI: 10.1091/mbc.e14-11-1554] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Cytohesin Arf-GEFs are conserved plasma membrane regulators. The sole Drosophila cytohesin, Steppke, restrains Rho1-dependent membrane cytoskeleton activity at the base of plasma membrane furrows of the syncytial embryo. By mass spectrometry, we identified a single major Steppke-interacting protein from syncytial embryos, which we named Stepping stone (Sstn). By sequence, Sstn seems to be a divergent homologue of the mammalian cytohesin adaptor FRMD4A. Our experiments supported this relationship. Specifically, heterophilic coiled-coil interactions linked Sstn and Steppke in vivo and in vitro, whereas a separate C-terminal region was required for Sstn localization to furrows. Sstn mutant and RNAi embryos displayed abnormal, Rho1-dependent membrane cytoskeleton expansion from the base of pseudocleavage and cellularization furrows, closely mimicking Steppke loss-of-function embryos. Elevating Sstn furrow levels had no effect on the steppke phenotype, but elevating Steppke furrow levels reversed the sstn phenotype, suggesting that Steppke acts downstream of Sstn and that additional mechanisms can recruit Steppke to furrows. Finally, the coiled-coil domain of Steppke was required for Sstn binding and in addition homodimerization, and its removal disrupted Steppke furrow localization and activity in vivo. Overall we propose that Sstn acts as a cytohesin adaptor that promotes Steppke activity for localized membrane cytoskeleton restraint in the syncytial Drosophila embryo.
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Affiliation(s)
- Jiangshu Liu
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Donghoon M Lee
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Cao Guo Yu
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Stephane Angers
- Department of Pharmaceutical Sciences, Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, ON M5S 3G5, Canada Department of Biochemistry, University of Toronto, Toronto, ON M5S 3G5, Canada
| | - Tony J C Harris
- Department of Cell and Systems Biology, University of Toronto, Toronto, ON M5S 3G5, Canada
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