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Singh D, Liu Y, Zhu YH, Zhang S, Naegele S, Wu JQ. Septins function in exocytosis via physical interactions with the exocyst complex in fission yeast cytokinesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.07.09.602728. [PMID: 39026698 PMCID: PMC11257574 DOI: 10.1101/2024.07.09.602728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/20/2024]
Abstract
Septins can function as scaffolds for protein recruitment, membrane-bound diffusion barriers, or membrane curvature sensors. Septins are important for cytokinesis, but their exact roles are still obscure. In fission yeast, four septins (Spn1 to Spn4) accumulate at the rim of the division plane as rings. The octameric exocyst complex, which tethers exocytic vesicles to the plasma membrane, exhibits a similar localization and is essential for plasma membrane deposition during cytokinesis. Without septins, the exocyst spreads across the division plane but absent from the rim during septum formation. These results suggest that septins and the exocyst physically interact for proper localization. Indeed, we predicted six pairs of direct interactions between septin and exocyst subunits by AlphaFold2 ColabFold, most of them are confirmed by co-immunoprecipitation and yeast two-hybrid assays. Exocyst mislocalization results in mistargeting of secretory vesicles and their cargos, which leads to cell-separation delay in septin mutants. Our results indicate that septins guide the targeting of exocyst complex on the plasma membrane for vesicle tethering during cytokinesis through direct physical interactions.
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2
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Morishita J, Nurse P. Identification of a small RhoA GTPase inhibitor effective in fission yeast and human cells. Open Biol 2023; 13:220185. [PMID: 36854376 PMCID: PMC9974304 DOI: 10.1098/rsob.220185] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/02/2023] Open
Abstract
The Rho GTPase family proteins are key regulators of cytoskeletal dynamics. Deregulated activity of Rho GTPases is associated with cancers and neurodegenerative diseases, and their potential as drug targets has long been recognized. Using an economically effective drug screening workflow in fission yeast and human cells, we have identified a Rho GTPase inhibitor, O1. By a suppressor mutant screen in fission yeast, we find a point mutation in the rho1 gene that confers resistance to O1. Consistent with the idea that O1 is the direct inhibitor of Rho1, O1 reduced the cellular amount of activated, GTP-bound Rho1 in wild-type cells, but not in the O1-resistant mutant cells, in which the evolutionarily conserved Ala62 residue is mutated to Thr. Similarly, O1 inhibits activity of the human orthologue RhoA GTPase in tissue culture cells. Our studies illustrate the power of yeast phenotypic screens in the identification and characterization of drugs relevant to human cells and have identified a novel GTPase inhibitor for fission yeast and human cells.
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Affiliation(s)
- Jun Morishita
- Laboratory of Yeast Genetics and Cell Biology, Rockefeller University, New York, NY 10065, USA
| | - Paul Nurse
- Laboratory of Yeast Genetics and Cell Biology, Rockefeller University, New York, NY 10065, USA
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
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Campbell BF, Hercyk BS, Williams AR, San Miguel E, Young HG, Das ME. Cdc42 GTPase activating proteins Rga4 and Rga6 coordinate septum synthesis and membrane trafficking at the division plane during cytokinesis. Traffic 2022; 23:478-495. [PMID: 36068165 DOI: 10.1111/tra.12864] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 07/25/2022] [Accepted: 08/12/2022] [Indexed: 11/29/2022]
Abstract
Fission yeast cytokinesis is driven by simultaneous septum synthesis, membrane furrowing and actomyosin ring constriction. The septum consists of a primary septum flanked by secondary septa. First, delivery of the glucan synthase Bgs1 and membrane vesicles initiate primary septum synthesis and furrowing. Next, Bgs4 is delivered for secondary septum formation. It is unclear how septum synthesis is coordinated with membrane furrowing. Cdc42 promotes delivery of Bgs1 but not Bgs4. We find that after primary septum initiation, Cdc42 inactivators Rga4 and Rga6 localize to the division site. In rga4Δrga6Δ mutants, Cdc42 activity is enhanced during late cytokinesis and cells take longer to separate. Electron micrographs of the division site in these mutants exhibit malformed septum with irregular membrane structures. These mutants have a larger division plane with enhanced Bgs1 delivery but fail to enhance accumulation of Bgs4 and several exocytic proteins. Additionally, these mutants show endocytic defects at the division site. This suggests that Cdc42 regulates primary septum formation and only certain membrane trafficking events. As cytokinesis progresses Rga4 and Rga6 localize to the division site to decrease Cdc42 activity to allow coupling of Cdc42-independent membrane trafficking events with septum formation for proper septum morphology.
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Affiliation(s)
- Bethany F Campbell
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Brian S Hercyk
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Ashlei R Williams
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Ema San Miguel
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Haylee G Young
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
| | - Maitreyi E Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee, USA
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Cansado J, Soto T, Franco A, Vicente-Soler J, Madrid M. The Fission Yeast Cell Integrity Pathway: A Functional Hub for Cell Survival upon Stress and Beyond. J Fungi (Basel) 2021; 8:jof8010032. [PMID: 35049972 PMCID: PMC8781887 DOI: 10.3390/jof8010032] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2021] [Revised: 12/27/2021] [Accepted: 12/27/2021] [Indexed: 12/11/2022] Open
Abstract
The survival of eukaryotic organisms during environmental changes is largely dependent on the adaptive responses elicited by signal transduction cascades, including those regulated by the Mitogen-Activated Protein Kinase (MAPK) pathways. The Cell Integrity Pathway (CIP), one of the three MAPK pathways found in the simple eukaryote fission of yeast Schizosaccharomyces pombe, shows strong homology with mammalian Extracellular signal-Regulated Kinases (ERKs). Remarkably, studies over the last few decades have gradually positioned the CIP as a multi-faceted pathway that impacts multiple functional aspects of the fission yeast life cycle during unperturbed growth and in response to stress. They include the control of mRNA-stability through RNA binding proteins, regulation of calcium homeostasis, and modulation of cell wall integrity and cytokinesis. Moreover, distinct evidence has disclosed the existence of sophisticated interplay between the CIP and other environmentally regulated pathways, including Stress-Activated MAP Kinase signaling (SAPK) and the Target of Rapamycin (TOR). In this review we present a current overview of the organization and underlying regulatory mechanisms of the CIP in S. pombe, describe its most prominent functions, and discuss possible targets of and roles for this pathway. The evolutionary conservation of CIP signaling in the dimorphic fission yeast S. japonicus will also be addressed.
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Rich-Robinson J, Russell A, Mancini E, Das M. Cdc42 reactivation at growth sites is regulated by local cell-cycle-dependent loss of its GTPase-activating protein Rga4 in fission yeast. J Cell Sci 2021; 134:272049. [PMID: 34523683 DOI: 10.1242/jcs.259291] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2021] [Accepted: 08/18/2021] [Indexed: 12/18/2022] Open
Abstract
In fission yeast, polarized cell growth stops during division and resumes after cytokinesis completes and cells separate. It is unclear how growth reactivation is timed to occur immediately after cell separation. We uncoupled these sequential events by delaying cytokinesis with a temporary Latrunculin A treatment. Mitotic cells recovering from treatment initiate end growth during septation, displaying a polar elongation simultaneous with septation (PrESS) phenotype. PrESS cell ends reactivate Cdc42, a major regulator of polarized growth, during septation, but at a fixed time after anaphase B. A candidate screen implicates Rga4, a negative regulator of Cdc42, in this process. We show that Rga4 appears punctate at the cell sides during G2, but is diffuse during mitosis, extending to the ends. Although the Morphogenesis Orb6 (MOR) pathway is known to promote cell separation and growth by activating protein synthesis, we find that, for polarized growth, removal of Rga4 from the ends is also necessary. Therefore, we propose that growth resumes after division once the MOR pathway is activated and the ends lose Rga4 in a cell-cycle-dependent manner.
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Affiliation(s)
- Julie Rich-Robinson
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Afton Russell
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Eleanor Mancini
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
| | - Maitreyi Das
- Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, USA
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Vicente-Soler J, Soto T, Franco A, Cansado J, Madrid M. The Multiple Functions of Rho GTPases in Fission Yeasts. Cells 2021; 10:1422. [PMID: 34200466 PMCID: PMC8228308 DOI: 10.3390/cells10061422] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2021] [Revised: 06/03/2021] [Accepted: 06/04/2021] [Indexed: 01/20/2023] Open
Abstract
The Rho family of GTPases represents highly conserved molecular switches involved in a plethora of physiological processes. Fission yeast Schizosaccharomyces pombe has become a fundamental model organism to study the functions of Rho GTPases over the past few decades. In recent years, another fission yeast species, Schizosaccharomyces japonicus, has come into focus offering insight into evolutionary changes within the genus. Both fission yeasts contain only six Rho-type GTPases that are spatiotemporally controlled by multiple guanine-nucleotide exchange factors (GEFs) and GTPase-activating proteins (GAPs), and whose intricate regulation in response to external cues is starting to be uncovered. In the present review, we will outline and discuss the current knowledge and recent advances on how the fission yeasts Rho family GTPases regulate essential physiological processes such as morphogenesis and polarity, cellular integrity, cytokinesis and cellular differentiation.
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Affiliation(s)
| | | | | | - José Cansado
- Yeast Physiology Group, Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; (J.V.-S.); (T.S.); (A.F.)
| | - Marisa Madrid
- Yeast Physiology Group, Departamento de Genética y Microbiología, Facultad de Biología, Universidad de Murcia, 30100 Murcia, Spain; (J.V.-S.); (T.S.); (A.F.)
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Gene Expression of Putative Pathogenicity-Related Genes in Verticillium dahliae in Response to Elicitation with Potato Extracts and during Infection Using Quantitative Real-Time PCR. Pathogens 2021; 10:pathogens10050510. [PMID: 33922492 PMCID: PMC8146963 DOI: 10.3390/pathogens10050510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2021] [Revised: 04/19/2021] [Accepted: 04/21/2021] [Indexed: 11/17/2022] Open
Abstract
Quantitative real-time PCR was used to monitor the expression of 15 Verticillium dahliae's genes, putatively involved in pathogenicity, highly (HAV) and weakly aggressive (WAV) V. dahliae isolates after either (i) elicitation with potato leaf, stem, or root extracts, or (ii) inoculation of potato detached petioles. These genes, i.e., coding for Ras-GAP-like protein, serine/threonine protein kinase, Ubiquitin-conjugating enzyme variant-MMS2, NADH-ubiquinone oxidoreductase, Thioredoxin, Pyruvate dehydrogenase E1 VdPDHB, myo-inositol 2-dehydrogenase, and HAD-superfamily hydrolase, showed differential upregulation in the HAV versus WAV isolate in response to plant extracts or after inoculation of potato leaf petioles. This suggests their potential involvement in the observed differential aggressiveness between isolates. However, other genes like glucan endo-1,3-alpha-glucosidase and nuc-1 negative regulatory protein VdPREG showed higher activity in the WAV than in the HAV in response to potato extracts and/or during infection. This, in contrast, may suggest a role in their lower aggressiveness. These findings, along with future functional analysis of selected genes, will contribute to improving our understanding of V. dahliae's pathogenesis. For example, expression of VdPREG negatively regulates phosphorus-acquisition enzymes, which may indicate a lower phosphorus acquisition activity in the WAV. Therefore, integrating the knowledge about the activity of both genes enhancing pathogenicity and those restraining it will provide a guild line for further functional characterization of the most critical genes, thus driving new ideas towards better Verticillium wilt management.
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Hercyk BS, Onwubiko UN, Das ME. Coordinating septum formation and the actomyosin ring during cytokinesis in Schizosaccharomyces pombe. Mol Microbiol 2019; 112:1645-1657. [PMID: 31533197 PMCID: PMC6904431 DOI: 10.1111/mmi.14387] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/12/2019] [Indexed: 01/08/2023]
Abstract
During cytokinesis, animal and fungal cells form a membrane furrow via actomyosin ring constriction. Our understanding of actomyosin ring-driven cytokinesis stems extensively from the fission yeast model system. However, unlike animal cells, actomyosin ring constriction occurs simultaneously with septum formation in fungi. While the formation of an actomyosin ring is essential for cytokinesis in fission yeast, proper furrow formation also requires septum deposition. The molecular mechanisms of spatiotemporal coordination of septum deposition with actomyosin ring constriction are poorly understood. Although the role of the actomyosin ring as a mechanical structure driving furrow formation is better understood, its role as a spatiotemporal landmark for septum deposition is not widely discussed. Here we review and discuss the recent advances describing how the actomyosin ring spatiotemporally regulates membrane traffic to promote septum-driven cytokinesis in fission yeast. Finally, we explore emerging questions in cytokinesis, and discuss the role of extracellular matrix during cytokinesis in other organisms.
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Affiliation(s)
- Brian S Hercyk
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Udo N Onwubiko
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
| | - Maitreyi E Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, 37996, USA
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9
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Hercyk B, Das M. Rho Family GTPases in Fission Yeast Cytokinesis. Commun Integr Biol 2019; 12:171-180. [PMID: 31666919 PMCID: PMC6802929 DOI: 10.1080/19420889.2019.1678453] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Revised: 09/20/2019] [Accepted: 09/23/2019] [Indexed: 12/22/2022] Open
Abstract
During cytokinesis, actomyosin ring constriction drives furrow formation. In animal cells, Rho GTPases drive this process through the positioning and assembly of the actomyosin ring, and through extracellular matrix remodeling within the furrow. In the fission yeast S. pombe, actomyosin ring constriction and septum formation are concurrent processes. While S. pombe is the primary source from which the mechanics of ring assembly and constriction stem, much less is known about the regulation of Rho GTPases that control these processes. Of the six Rho GTPases encoded in S. pombe, only Rho1, the RhoA homologue, has been shown to be essential for cytokinesis. While Rho3, Rho4, and Cdc42 have defined roles in cytokinesis, Rho2 and Rho5 play minor to no roles in this process. Here we review the roles of the Rho GTPases during cytokinesis, with a focus on their regulation, and discuss whether crosstalk between GTPases, as has been reported in other organisms, exists during cytokinesis in S. pombe.
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Affiliation(s)
- Brian Hercyk
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
| | - Maitreyi Das
- Department of Biochemistry & Cellular and Molecular Biology, University of Tennessee, Knoxville, TN, USA
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10
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Marsalek L, Puxbaum V, Buchetics M, Mattanovich D, Gasser B. Disruption of vacuolar protein sorting components of the HOPS complex leads to enhanced secretion of recombinant proteins in Pichia pastoris. Microb Cell Fact 2019; 18:119. [PMID: 31269943 PMCID: PMC6607557 DOI: 10.1186/s12934-019-1155-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 06/04/2019] [Indexed: 12/14/2022] Open
Abstract
Background The yeast Pichia pastoris is a widely used host for the secretion of heterologous proteins. Despite being an efficient producer, we observed previously that certain recombinant proteins were mistargeted to the vacuole on their route to secretion. Simultaneous disruption of one vacuolar sorting pathway together with vacuolar proteases prevented this mis-sorting and resulted in higher levels of secreted heterologous protein. Inspired by the positive results, we now set out to investigate the influence of further parts of the vacuolar pathway, namely the Cvt-pathway and the homotypic fusion and protein sorting (HOPS) complex. Results Strains impaired in the Cvt pathway (∆atg11, ∆atg8) had no effect on secretion of the model protein carboxylesterase (CES), but resulted in lower secretion levels of the antibody fragment HyHEL-Fab. Disruption of genes involved in the HOPS complex led to vacuole-like compartments of the B category of vps mutants, which are characteristic for the deleted genes YPT7, VPS41 and VAM6. In particular ∆ypt7 and ∆vam6 strains showed an improvement in secreting the model proteins HyHEL-Fab and CES. Additional disruption of the vacuolar protease Pep4 and the potential protease Vps70 led to even further enhanced secretion in ∆ypt7 and ∆vam6 strains. Nevertheless, intracellular product accumulation was still observed. Therefore, the secretory route was strengthened by overexpression of early or late secretory genes in the vacuolar sorting mutants. Thereby, overexpression of Sbh1, a subunit of the ER translocation pore, significantly increased HyHEL-Fab secretion, leading up to fourfold higher extracellular Fab levels in the ∆ypt7 strain. The beneficial impact on protein secretion and the suitability of these strains for industrial applicability was confirmed in fed-batch cultivations. Conclusions Disruption of genes involved in the HOPS complex, especially YPT7, has a great influence on the secretion of the two different model proteins HyHEL-Fab and CES. Therefore, disruption of HOPS genes shows a high potential to increase secretion of other recombinant proteins as well. Secretion of HyHEL-Fab was further enhanced when overexpressing secretion enhancing factors. As the positive effect was also present in fed-batch cultivations, these modifications likely have promising industrial relevance. Electronic supplementary material The online version of this article (10.1186/s12934-019-1155-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Lukas Marsalek
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Muthgasse 11, 1190, Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | - Verena Puxbaum
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Muthgasse 11, 1190, Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | - Markus Buchetics
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Muthgasse 11, 1190, Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria.,BHAK/BHAS Stegersbach, Kirchengasse 44, 7551, Stegersbach, Austria
| | - Diethard Mattanovich
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Muthgasse 11, 1190, Vienna, Austria.,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria
| | - Brigitte Gasser
- Austrian Centre of Industrial Biotechnology (ACIB GmbH), Muthgasse 11, 1190, Vienna, Austria. .,Department of Biotechnology, BOKU-University of Natural Resources and Life Sciences, Muthgasse 18, 1190, Vienna, Austria.
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11
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Pérez P, Soto T, Gómez-Gil E, Cansado J. Functional interaction between Cdc42 and the stress MAPK signaling pathway during the regulation of fission yeast polarized growth. Int Microbiol 2019; 23:31-41. [PMID: 30989357 DOI: 10.1007/s10123-019-00072-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/18/2019] [Accepted: 03/20/2019] [Indexed: 12/12/2022]
Abstract
Cell polarization can be defined as the generation and maintenance of directional cellular organization. The spatial distribution and protein or lipid composition of the cell are not symmetric but organized in specialized domains which allow cells to grow and acquire a certain shape that is closely linked to their physiological function. The establishment and maintenance of polarized growth requires the coordination of diverse processes including cytoskeletal dynamics, membrane trafficking, and signaling cascade regulation. Some of the major players involved in the selection and maintenance of sites for polarized growth are Rho GTPases, which recognize the polarization site and transmit the signal to regulatory proteins of the cytoskeleton. Additionally, cytoskeletal organization, polarized secretion, and endocytosis are controlled by signaling pathways including those mediated by mitogen-activated protein kinases (MAPKs). Rho GTPases and the MAPK signaling pathways are strongly conserved from yeast to mammals, suggesting that the basic mechanisms of polarized growth have been maintained throughout evolution. For this reason, the study of how polarized growth is established and regulated in simple organisms such as the fission yeast Schizosaccharomyces pombe has contributed to broaden our knowledge about these processes in multicellular organisms. We review here the function of the Cdc42 GTPase and the stress activated MAPK (SAPK) signaling pathways during fission yeast polarized growth, and discuss the relevance of the crosstalk between both pathways.
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Affiliation(s)
- Pilar Pérez
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas and Universidad de Salamanca, 37007, Salamanca, Spain.
| | - Teresa Soto
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071, Murcia, Spain
| | - Elisa Gómez-Gil
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071, Murcia, Spain
| | - Jose Cansado
- Yeast Physiology Group, Department of Genetics and Microbiology, Facultad de Biología, Universidad de Murcia, 30071, Murcia, Spain.
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12
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Role and organization of the actin cytoskeleton during cell-cell fusion. Semin Cell Dev Biol 2016; 60:121-126. [PMID: 27476112 DOI: 10.1016/j.semcdb.2016.07.025] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 07/25/2016] [Accepted: 07/26/2016] [Indexed: 11/23/2022]
Abstract
Cell-cell fusion is a ubiquitous process that underlies fertilization and development of eukaryotes. This process requires fusogenic machineries to promote plasma membrane merging, and also relies on the organization of dedicated sub-cortical cytoskeletal assemblies. This review describes the role of actin structures, so called actin fusion foci, essential for the fusion of two distinct cell types: Drosophila myoblast cells, which fuse to form myotubes, and sexually differentiated cells of the fission yeast Schizosaccharomyces pombe, which fuse to form a zygote. I describe the respective composition and organization of the two structures, discuss their proposed role in promoting plasma membrane apposition, and consider the universality of similar structures for cell-cell fusion.
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13
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Pérez P, Cortés JCG, Martín-García R, Ribas JC. Overview of fission yeast septation. Cell Microbiol 2016; 18:1201-7. [PMID: 27155541 DOI: 10.1111/cmi.12611] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 05/02/2016] [Accepted: 05/05/2016] [Indexed: 02/04/2023]
Abstract
Cytokinesis is the final process of the vegetative cycle, which divides a cell into two independent daughter cells once mitosis is completed. In fungi, as in animal cells, cytokinesis requires the formation of a cleavage furrow originated by constriction of an actomyosin ring which is connected to the plasma membrane and causes its invagination. Additionally, because fungal cells have a polysaccharide cell wall outside the plasma membrane, cytokinesis requires the formation of a septum coincident with the membrane ingression. Fission yeast Schizosaccharomyces pombe is a unicellular, rod-shaped fungus that has become a popular model organism for the study of actomyosin ring formation and constriction during cell division. Here we review the current knowledge of the septation and separation processes in this fungus, as well as recent advances in understanding the functional interaction between the transmembrane enzymes that build the septum and the actomyosin ring proteins.
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Affiliation(s)
- Pilar Pérez
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, 37007, Spain
| | - Juan C G Cortés
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, 37007, Spain
| | - Rebeca Martín-García
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, 37007, Spain
| | - Juan C Ribas
- Instituto de Biología Funcional y Genómica, Consejo Superior de Investigaciones Científicas (CSIC), Universidad de Salamanca, Salamanca, 37007, Spain
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14
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Martín-García R, Santos B. The price of independence: cell separation in fission yeast. World J Microbiol Biotechnol 2016; 32:65. [PMID: 26931605 DOI: 10.1007/s11274-016-2021-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2015] [Accepted: 01/29/2016] [Indexed: 12/28/2022]
Abstract
The ultimate goal of cell division is to give rise to two viable independent daughter cells. A tight spatial and temporal regulation between chromosome segregation and cytokinesis ensures the viability of the daughter cells. Schizosaccharomyces pombe, commonly known as fission yeast, has become a leading model organism for studying essential and conserved mechanisms of the eukaryotic cell division process. Like many other eukaryotic cells it divides by binary fission and the cleavage furrow undergoes ingression due to the contraction of an actomyosin ring. In contrast to mammalian cells, yeasts as cell-walled organisms, also need to form a division septum made of cell wall material to complete the process of cytokinesis. The division septum is deposited behind the constricting ring and it will constitute the new ends of the daughter cells. Cell separation also involves cell wall degradation and this process should be precisely regulated to avoid cell lysis. In this review, we will give a brief overview of the whole cytokinesis process in fission yeast, from the positioning and assembly of the contractile ring to the final step of cell separation, and the problems generated when these processes are not precise.
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Affiliation(s)
- Rebeca Martín-García
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007, Salamanca, Spain
| | - Beatriz Santos
- Instituto de Biología Funcional y Genómica (IBFG), Consejo Superior de Investigaciones Científicas, University of Salamanca, 37007, Salamanca, Spain.
- Departamento de Microbiología y Genética, University of Salamanca, 37007, Salamanca, Spain.
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15
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Rincon SA, Paoletti A. Molecular control of fission yeast cytokinesis. Semin Cell Dev Biol 2016; 53:28-38. [PMID: 26806637 DOI: 10.1016/j.semcdb.2016.01.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 01/06/2016] [Indexed: 12/29/2022]
Abstract
Cytokinesis gives rise to two independent daughter cells at the end of the cell division cycle. The fission yeast Schizosaccharomyces pombe has emerged as one of the most powerful systems to understand how cytokinesis is controlled molecularly. Like in most eukaryotes, fission yeast cytokinesis depends on an acto-myosin based contractile ring that assembles at the division site under the control of spatial cues that integrate information on cell geometry and the position of the mitotic apparatus. Cytokinetic events are also tightly coordinated with nuclear division by the cell cycle machinery. These spatial and temporal regulations ensure an equal cleavage of the cytoplasm and an accurate segregation of the genetic material in daughter cells. Although this model system has specificities, the basic mechanisms of contractile ring assembly and function deciphered in fission yeast are highly valuable to understand how cytokinesis is controlled in other organisms that rely on a contractile ring for cell division.
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Affiliation(s)
- Sergio A Rincon
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France
| | - Anne Paoletti
- Institut Curie, Centre de Recherche, PSL Research University, F-75248 Paris, France; CNRS UMR144, F-75248 Paris, France.
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Willet AH, McDonald NA, Gould KL. Regulation of contractile ring formation and septation in Schizosaccharomyces pombe. Curr Opin Microbiol 2015; 28:46-52. [PMID: 26340438 DOI: 10.1016/j.mib.2015.08.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 08/01/2015] [Accepted: 08/07/2015] [Indexed: 01/14/2023]
Abstract
The fission yeast Schizosaccharomyces pombe has become a powerful model organism for cytokinesis studies, propelled by pioneering genetic screens in the 1980s and 1990s. S. pombe cells are rod-shaped and divide similarly to mammalian cells, utilizing a medially-placed actin-and myosin-based contractile ring. A cell wall division septum is deposited behind the constricting ring, forming the new ends of each daughter cell. Here we discuss recent advances in our understanding of the regulation of contractile ring formation through formin proteins and the role of the division septum in S. pombe cell division.
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Affiliation(s)
- Alaina H Willet
- Department of Cell and Developmental Biology, PMB 407935, 465 21st Ave S., Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Nathan A McDonald
- Department of Cell and Developmental Biology, PMB 407935, 465 21st Ave S., Vanderbilt University School of Medicine, Nashville, TN, United States
| | - Kathleen L Gould
- Department of Cell and Developmental Biology, PMB 407935, 465 21st Ave S., Vanderbilt University School of Medicine, Nashville, TN, United States.
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17
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Pérez P, Portales E, Santos B. Rho4 interaction with exocyst and septins regulates cell separation in fission yeast. MICROBIOLOGY-SGM 2015; 161:948-959. [PMID: 25724972 DOI: 10.1099/mic.0.000062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2014] [Accepted: 02/18/2015] [Indexed: 12/17/2022]
Abstract
Rho GTPases are small proteins present in all eukaryotic cells, from yeast to mammals, with a function in actin organization and morphogenetic processes. Schizosaccharomyces pombe Rho4 is not essential but it displays a role during cell separation at high temperature. In fact, Rho4 is involved in the secretion of the hydrolytic enzymes that are required for cell septum degradation during this process. In rho4Δ cells, vesicles accumulate in the septum area and the glucanases Eng1 and Agn1 are not secreted to the culture medium. The localization of Eng1 and Agn1 depends on the exocyst and the septins. The exocyst is a conserved multiprotein complex important for the targeting and fusion of Golgi-derived vesicles with the plasma membrane. Septins are a family of GTP-binding proteins conserved in eukaryotes that function during cytokinesis. Here we show that Rho4 is required for the proper localization of the exocyst and septins at high temperature. Moreover, pull-down experiments demonstrate that Rho4 can interact with exocyst subunits, such as Sec8 and Exo70, and septin proteins, such as Spn3. We observe that Sec8 preferentially binds to activated GTP-Rho4, suggesting that Sec8 could be an effector of this GTPase. We propose that the interaction of Rho4 with the exocyst and septins confers a precise regulation for the secretion of glucanases at the appropriate place and time during the cell cycle.
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Affiliation(s)
- Pilar Pérez
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Elvira Portales
- Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
| | - Beatriz Santos
- Departamento de Microbiología y Genética, Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain.,Instituto de Biología Funcional y Genómica (IBFG), CSIC/Universidad de Salamanca, Avd. Zacarías González s/n, 37007 Salamanca, Spain
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18
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Doi A, Kita A, Kanda Y, Uno T, Asami K, Satoh R, Nakano K, Sugiura R. Geranylgeranyltransferase Cwg2-Rho4/Rho5 module is implicated in the Pmk1 MAP kinase-mediated cell wall integrity pathway in fission yeast. Genes Cells 2015; 20:310-23. [DOI: 10.1111/gtc.12222] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2014] [Accepted: 12/15/2014] [Indexed: 11/27/2022]
Affiliation(s)
- Akira Doi
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
- Japan Society for the Promotion of Science; 1-8 Chiyoda-ku Tokyo 102-8472 Japan
| | - Ayako Kita
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
| | - Yuki Kanda
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
| | - Takaya Uno
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
| | - Keita Asami
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
| | - Ryosuke Satoh
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
| | - Kentaro Nakano
- Department of Biological Sciences; Graduate School of Life and Environmental Sciences; University of Tsukuba; 1-1-1 Tennohdai Tsukuba Ibaraki 305-8577 Japan
| | - Reiko Sugiura
- Laboratory of Molecular Pharmacogenomics; School of Pharmaceutical Sciences; Kinki University; Kowakae 3-4-1 Higashi-Osaka 577-8502 Japan
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Ruiz-Roldán C, Pareja-Jaime Y, González-Reyes JA, Roncero MIG. The Transcription Factor Con7-1 Is a Master Regulator of Morphogenesis and Virulence in Fusarium oxysporum. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2015; 28:55-68. [PMID: 25271883 DOI: 10.1094/mpmi-07-14-0205-r] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Previous studies have demonstrated the essential role of morphogenetic regulation in Fusarium oxysporum pathogenesis, including processes such as cell-wall biogenesis, cell division, and differentiation of infection-like structures. We identified three F. oxysporum genes encoding predicted transcription factors showing significant identities to Magnaporthe oryzae Con7p, Con7-1, plus two identical copies of Con7-2. Targeted deletion of con7-1 produced nonpathogenic mutants with altered morphogenesis, including defects in cell wall structure, polar growth, hyphal branching, and conidiation. By contrast, simultaneous inactivation of both con7-2 copies caused no detectable defects in the resulting mutants. Comparative microarray-based gene expression analysis indicated that Con7-1 modulates the expression of a large number of genes involved in different biological functions, including host-pathogen interactions, morphogenesis and development, signal perception and transduction, transcriptional regulation, and primary and secondary metabolism. Taken together, our results point to Con7-1 as general regulator of morphogenesis and virulence in F. oxysporum.
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Wang N, Wang M, Zhu YH, Grosel TW, Sun D, Kudryashov DS, Wu JQ. The Rho-GEF Gef3 interacts with the septin complex and activates the GTPase Rho4 during fission yeast cytokinesis. Mol Biol Cell 2014; 26:238-55. [PMID: 25411334 PMCID: PMC4294672 DOI: 10.1091/mbc.e14-07-1196] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Rho GTPases, activated by Rho guanine nucleotide exchange factors (GEFs), are conserved molecular switches for signal transductions that regulate diverse cellular processes, including cell polarization and cytokinesis. The fission yeast Schizosaccharomyces pombe has six Rho GTPases (Cdc42 and Rho1-Rho5) and seven Rho GEFs (Scd1, Rgf1-Rgf3, and Gef1-Gef3). The GEFs for Rho2-Rho5 have not been unequivocally assigned. In particular, Gef3, the smallest Rho GEF, was barely studied. Here we show that Gef3 colocalizes with septins at the cell equator. Gef3 physically interacts with septins and anillin Mid2 and depends on them to localize. Gef3 coprecipitates with GDP-bound Rho4 in vitro and accelerates nucleotide exchange of Rho4, suggesting that Gef3 is a GEF for Rho4. Consistently, Gef3 and Rho4 are in the same genetic pathways to regulate septum formation and/or cell separation. In gef3∆ cells, the localizations of two potential Rho4 effectors--glucanases Eng1 and Agn1--are abnormal, and active Rho4 level is reduced, indicating that Gef3 is involved in Rho4 activation in vivo. Moreover, overexpression of active Rho4 or Eng1 rescues the septation defects of mutants containing gef3∆. Together our data support that Gef3 interacts with the septin complex and activates Rho4 GTPase as a Rho GEF for septation in fission yeast.
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Affiliation(s)
| | - Mo Wang
- Department of Molecular Genetics
| | | | | | | | | | - Jian-Qiu Wu
- Department of Molecular Genetics Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210
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21
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Flor-Parra I, Bernal M, Zhurinsky J, Daga RR. Cell migration and division in amoeboid-like fission yeast. Biol Open 2014; 3:108-15. [PMID: 24357230 PMCID: PMC3892166 DOI: 10.1242/bio.20136783] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Yeast cells are non-motile and are encased in a cell wall that supports high internal turgor pressure. The cell wall is also essential for cellular morphogenesis and cell division. Here, we report unexpected morphogenetic changes in a Schizosaccharomyces pombe mutant defective in cell wall biogenesis. These cells form dynamic cytoplasmic protrusions caused by internal turgor pressure and also exhibit amoeboid-like cell migration resulting from repeated protrusive cycles. The cytokinetic ring responsible for cell division in wild-type yeast often fails in these cells; however, they were still able to divide using a ring-independent alternative mechanism relying on extrusion of the cell body through a hole in the cell wall. This mechanism of cell division may resemble an ancestral mode of division in the absence of cytokinetic machinery. Our findings highlight how a single gene change can lead to the emergence of different modes of cell growth, migration and division.
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Affiliation(s)
- Ignacio Flor-Parra
- Centro Andaluz de Biología del Desarrollo, Universidad Pablo de Olavide-Consejo Superior de Investigaciones Científicas, 41013 Sevilla, Spain
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22
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Zhang C, Wang Y, Wang J, Zhai Z, Zhang L, Zheng W, Zheng W, Yu W, Zhou J, Lu G, Shim WB, Wang Z. Functional characterization of Rho family small GTPases in Fusarium graminearum. Fungal Genet Biol 2013; 61:90-9. [DOI: 10.1016/j.fgb.2013.09.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2013] [Revised: 09/06/2013] [Accepted: 09/06/2013] [Indexed: 11/28/2022]
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23
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Zhu YH, Ye Y, Wu Z, Wu JQ. Cooperation between Rho-GEF Gef2 and its binding partner Nod1 in the regulation of fission yeast cytokinesis. Mol Biol Cell 2013; 24:3187-204. [PMID: 23966468 PMCID: PMC3806657 DOI: 10.1091/mbc.e13-06-0301] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Previous results showed that putative Rho-GEF Gef2 regulates division-site positioning during early cytokinesis in fission yeast. Here Nod1 is identified as a binding partner of Gef2. The two proteins form a complex to regulate division-site positioning and contractile-ring maintenance. In addition, Gef2 binds to GTPases Rho1, Rho4, and Rho5 in vitro. Cytokinesis is the last step of the cell-division cycle, which requires precise spatial and temporal regulation to ensure genetic stability. Rho guanine nucleotide exchange factors (Rho GEFs) and Rho GTPases are among the key regulators of cytokinesis. We previously found that putative Rho-GEF Gef2 coordinates with Polo kinase Plo1 to control the medial cortical localization of anillin-like protein Mid1 in fission yeast. Here we show that an adaptor protein, Nod1, colocalizes with Gef2 in the contractile ring and its precursor cortical nodes. Like gef2∆, nod1∆ has strong genetic interactions with various cytokinesis mutants involved in division-site positioning, suggesting a role of Nod1 in early cytokinesis. We find that Nod1 and Gef2 interact through the C-termini, which is important for their localization. The contractile-ring localization of Nod1 and Gef2 also depends on the interaction between Nod1 and the F-BAR protein Cdc15, where the Nod1/Gef2 complex plays a role in contractile-ring maintenance and affects the septation initiation network. Moreover, Gef2 binds to purified GTPases Rho1, Rho4, and Rho5 in vitro. Taken together, our data indicate that Nod1 and Gef2 function cooperatively in a protein complex to regulate fission yeast cytokinesis.
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Affiliation(s)
- Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210 Department of Molecular and Cellular Biochemistry, The Ohio State University, Columbus, OH 43210 Department of Chemistry and Biochemistry, The Ohio State University, Columbus, OH 43210
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24
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25
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Eckler AM, Wilder C, Castanon A, Ferris VM, Lamere RA, Perrin BA, Pearlman R, White B, Byrd C, Ludvik N, Nichols N, Poole-Sumrall K, Sztul E, Styers ML. Haploinsufficiency of the Sec7 guanine nucleotide exchange factor gea1 impairs septation in fission yeast. PLoS One 2013; 8:e56807. [PMID: 23457617 PMCID: PMC3574105 DOI: 10.1371/journal.pone.0056807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2012] [Accepted: 01/15/2013] [Indexed: 11/19/2022] Open
Abstract
Membrane trafficking is essential to eukaryotic life and is controlled by a complex network of proteins that regulate movement of proteins and lipids between organelles. The GBF1/GEA family of Guanine nucleotide Exchange Factors (GEFs) regulates trafficking between the endoplasmic reticulum and Golgi by catalyzing the exchange of GDP for GTP on ADP Ribosylation Factors (Arfs). Activated Arfs recruit coat protein complex 1 (COP-I) to form vesicles that ferry cargo between these organelles. To further explore the function of the GBF1/GEA family, we have characterized a fission yeast mutant lacking one copy of the essential gene gea1 (gea1+/-), the Schizosaccharomyces pombe ortholog of GBF1. The haploinsufficient gea1+/- strain was shown to be sensitive to the GBF1 inhibitor brefeldin A (BFA) and was rescued from BFA sensitivity by gea1p overexpression. No overt defects in localization of arf1p or arf6p were observed in gea1+/- cells, but the fission yeast homolog of the COP-I cargo sac1 was mislocalized, consistent with impaired COP-I trafficking. Although Golgi morphology appeared normal, a slight increase in vacuolar size was observed in the gea1+/- mutant strain. Importantly, gea1+/- cells exhibited dramatic cytokinesis-related defects, including disorganized contractile rings, an increased septation index, and alterations in septum morphology. Septation defects appear to result from altered secretion of enzymes required for septum dynamics, as decreased secretion of eng1p, a β-glucanase required for septum breakdown, was observed in gea1+/- cells, and overexpression of eng1p suppressed the increased septation phenotype. These observations implicate gea1 in regulation of septum breakdown and establish S. pombe as a model system to explore GBF1/GEA function in cytokinesis.
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Affiliation(s)
- Alan M. Eckler
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Caroline Wilder
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Antonio Castanon
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Veronica M. Ferris
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Rachael A. Lamere
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Benjamin A. Perrin
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Ross Pearlman
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Blaise White
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Clifton Byrd
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nicholas Ludvik
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Nona Nichols
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Kristen Poole-Sumrall
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
| | - Elizabeth Sztul
- Department of Cell, Developmental, and Integrative Biology, University of Alabama at Birmingham, Birmingham, Alabama, United States of America
| | - Melanie L. Styers
- Department of Biology, Birmingham-Southern College, Birmingham, Alabama, United States of America
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26
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Gong T, Liao Y, He F, Yang Y, Yang DD, Chen XD, Gao XD. Control of polarized growth by the Rho family GTPase Rho4 in budding yeast: requirement of the N-terminal extension of Rho4 and regulation by the Rho GTPase-activating protein Bem2. EUKARYOTIC CELL 2013; 12:368-77. [PMID: 23264647 PMCID: PMC3571307 DOI: 10.1128/ec.00277-12] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 12/19/2012] [Indexed: 11/20/2022]
Abstract
In the budding yeast Saccharomyces cerevisiae, Rho4 GTPase partially plays a redundant role with Rho3 in the control of polarized growth, as deletion of RHO4 and RHO3 together, but not RHO4 alone, caused lethality and a loss of cell polarity at 30°C. Here, we show that overexpression of the constitutively active rho4(Q131L) mutant in an rdi1Δ strain caused a severe growth defect and generated large, round, unbudded cells, suggesting that an excess of Rho4 activity could block bud emergence. We also generated four temperature-sensitive rho4-Ts alleles in a rho3Δ rho4Δ strain. These mutants showed growth and morphological defects at 37°C. Interestingly, two rho4-Ts alleles contain mutations that cause amino acid substitutions in the N-terminal region of Rho4. Rho4 possesses a long N-terminal extension that is unique among the six Rho GTPases in the budding yeast but is common in Rho4 homologs in other yeasts and filamentous fungi. We show that the N-terminal extension plays an important role in Rho4 function since rho3Δ rho4(Δ)(61) cells expressing truncated Rho4 lacking amino acids (aa) 1 to 61 exhibited morphological defects at 24°C and a growth defect at 37°C. Furthermore, we show that Rho4 interacts with Bem2, a Rho GTPase-activating protein (RhoGAP) for Cdc42 and Rho1, by yeast two-hybrid, bimolecular fluorescence complementation (BiFC), and glutathione S-transferase (GST) pulldown assays. Bem2 specifically interacts with the GTP-bound form of Rho4, and the interaction is mediated by its RhoGAP domain. Overexpression of BEM2 aggravates the defects of rho3Δ rho4 mutants. These results suggest that Bem2 might be a novel GAP for Rho4.
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Affiliation(s)
- Ting Gong
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan, People's Republic of China
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27
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Raudaskoski M, Kothe E, Fowler TJ, Jung EM, Horton JS. Ras and Rho small G proteins: insights from the Schizophyllum commune genome sequence and comparisons to other fungi. Biotechnol Genet Eng Rev 2012; 28:61-100. [PMID: 22616482 DOI: 10.5661/bger-28-61] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
Unlike in animal cells and yeasts, the Ras and Rho small G proteins and their regulators have not received extensive research attention in the case of the filamentous fungi. In an effort to begin to rectify this deficiency, the genome sequence of the basidiomycete mushroom Schizophyllum commune was searched for all known components of the Ras and Rho signalling pathways. The results of this study should provide an impetus for further detailed investigations into their role in polarized hyphal growth, sexual reproduction and fruiting body development. These processes have long been the targets for genetic and cell biological research in this fungus.
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Affiliation(s)
- Marjatta Raudaskoski
- Department of Biology, University of Turku, Biocity A, Tykistökatu 6A, FI-20520 Turku, Finland
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28
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Ye Y, Lee IJ, Runge KW, Wu JQ. Roles of putative Rho-GEF Gef2 in division-site positioning and contractile-ring function in fission yeast cytokinesis. Mol Biol Cell 2012; 23:1181-95. [PMID: 22298427 PMCID: PMC3315812 DOI: 10.1091/mbc.e11-09-0800] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
How Rho-GEFs and Rho GTPases regulate division-site selection during cytokinesis in fission yeast is unknown. The Rho-GEF Gef2 interacts with the anillin Mid1 to regulate contractile-ring positioning and assembly in coordination with the polo kinase Plo1. In addition, Gef2 is involved in contractile-ring stability and disassembly. Cytokinesis is crucial for integrating genome inheritance and cell functions. In multicellular organisms, Rho-guanine nucleotide exchange factors (GEFs) and Rho GTPases are key regulators of division-plane specification and contractile-ring formation during cytokinesis, but how they regulate early steps of cytokinesis in fission yeast remains largely unknown. Here we show that putative Rho-GEF Gef2 and Polo kinase Plo1 coordinate to control the medial cortical localization and function of anillin-related protein Mid1. The division-site positioning defects of gef2∆ plo1-ts18 double mutant can be partially rescued by increasing Mid1 levels. We find that Gef2 physically interacts with the Mid1 N-terminus and modulates Mid1 cortical binding. Gef2 localization to cortical nodes and the contractile ring depends on its last 145 residues, and the DBL-homology domain is important for its function in cytokinesis. Our data suggest the interaction between Rho-GEFs and anillins is an important step in the signaling pathways during cytokinesis. In addition, Gef2 also regulates contractile-ring function late in cytokinesis and may negatively regulate the septation initiation network. Collectively, we propose that Gef2 facilitates and stabilizes Mid1 binding to the medial cortex, where the localized Mid1 specifies the division site and induces contractile-ring assembly.
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Affiliation(s)
- Yanfang Ye
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
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29
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Justa-Schuch D, Heilig Y, Richthammer C, Seiler S. Septum formation is regulated by the RHO4-specific exchange factors BUD3 and RGF3 and by the landmark protein BUD4 in Neurospora crassa. Mol Microbiol 2010; 76:220-35. [PMID: 20199606 DOI: 10.1111/j.1365-2958.2010.07093.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Rho GTPases have multiple, yet poorly defined functions during cytokinesis. By screening a Neurospora crassa knock-out collection for Rho guanine nucleotide exchange factor (GEF) mutants that phenocopy rho-4 defects (i.e. lack of septa, slow growth, abnormal branching and cytoplasmic leakage), we identified two strains defective in homologues of Bud3p and Rgf3 of budding and fission yeast respectively. The function of these proteins as RHO4-specific GEFs was determined by in vitro assays. In vivo microscopy suggested that the two GEFs and their target GTPase act as two independent modules during the selection of the septation site and the actual septation process. Furthermore, we determined that the N. crassa homologue of the anillinrelated protein BUD4 is required for septum initiation and that its deficiency leads to typical rho4 defects. Localization of BUD4 as a cortical ring prior to septation initiation was independent of functional BUD3 or RGF3. These data position BUD4 upstream of both RHO4 functions in the septation process and make BUD4 a prime candidate for a cortical marker protein involved in the selection of future septation sites. The persistence of both BUD proteins and of RHO4 at the septal pore suggests additional functions of these proteins at mature septa.
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Affiliation(s)
- Daniela Justa-Schuch
- Institut für Mikrobiologie und Genetik, Universität Göttingen, Göttingen, Germany
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30
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Abstract
Eukaryotic cells display a wide range of morphologies important for cellular function and development. A particular cell shape is made via the generation of asymmetry in the organization of cytoskeletal elements, usually leading to actin localization at sites of growth. The Rho family of GTPases is present in all eukaryotic cells, from yeast to mammals, and their role as key regulators in the signalling pathways that control actin organization and morphogenetic processes is well known. In the present review we will discuss the role of Rho GTPases as regulators of yeasts' polarized growth, their mechanism of activation and signalling pathways in Saccharomyces cerevisiae and Schizosaccharomyces pombe. These two model yeasts have been very useful in the study of the molecular mechanisms responsible for cell polarity. As in other organisms with cell walls, yeast's polarized growth is closely related to cell-wall biosynthesis, and Rho GTPases are critical modulators of this process. They provide the co-ordinated regulation of cell-wall biosynthetic enzymes and actin organization required to maintain cell integrity during vegetative growth.
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31
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Abstract
In cell-walled organisms, a cross wall (septum) is produced during cytokinesis, which then splits in certain organisms to allow the daughter cells to separate. The formation and the subsequent cleavage of the septum require wall synthesis and wall degradation, which need to be strictly coordinated in order to prevent cell lysis. The dividing fission yeast (Schizosaccharomyces) cell produces a three-layered septum in which the middle layer and a narrow band of the adjacent cell wall can be degraded without threatening the integrity of the separating daughter cells. This spatially very precise process requires the activity of the Agn1p 1,3-alpha-glucanase and the Eng1p 1,3-beta-glucanase, which are localized to the septum by a complex mechanism involving the formation of a septin ring and the directed activity of the exocyst system. The Sep1p-Ace2p transcription-factor cascade regulates the expression of many genes producing proteins for this complex process. Recent advances in research into the molecular mechanisms of separation and its regulation are discussed in this review.
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Rasmussen CG, Glass NL. Localization of RHO-4 indicates differential regulation of conidial versus vegetative septation in the filamentous fungus Neurospora crassa. EUKARYOTIC CELL 2007; 6:1097-107. [PMID: 17496127 PMCID: PMC1951110 DOI: 10.1128/ec.00050-07] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Rho-4 mutants of the filamentous fungus Neurospora crassa lack septa and asexual spores (conidia) and grow slowly. In this report, localization of green fluorescent protein-tagged RHO-4 is used to elucidate the differences in factors controlling RHO-4 localization during vegetative growth versus asexual development. RHO-4 forms a ring at incipient vegetative septation sites that constricts with the formation of the septum toward the septal pore; RHO-4 persists around the septal pore after septum completion. During the formation of conidia, RHO-4 localizes to the primary septum but subsequently is relocalized to the cytoplasm after the placement of the secondary septum. Cytoplasmic localization and inactivation of RHO-4 are mediated by a direct physical interaction with RDI-1, a RHO guanosine nucleotide dissociation inhibitor. Inappropriate activation of the cyclic AMP-dependent protein kinase A pathway during vegetative growth causes mislocalization of RHO-4 away from septa to the cytoplasm, a process which was dependent upon RDI-1. An adenylate cyclase cr-1 mutant partially suppresses the aconidial defect of rho-4 mutants but only rarely suppresses the vegetative septation defect, indicating that conidial septation is negatively regulated by CR-1. These data highlight the differences in the regulation of septation during conidiation versus vegetative septation in filamentous fungi.
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Affiliation(s)
- Carolyn G Rasmussen
- Department of Plant and Microbial Biology, 111 Koshland Hall, University of California, Berkeley, Berkeley, CA 94720-3102, USA
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Coll PM, Rincon SA, Izquierdo RA, Perez P. Hob3p, the fission yeast ortholog of human BIN3, localizes Cdc42p to the division site and regulates cytokinesis. EMBO J 2007; 26:1865-77. [PMID: 17363901 PMCID: PMC1847667 DOI: 10.1038/sj.emboj.7601641] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Accepted: 02/14/2007] [Indexed: 12/20/2022] Open
Abstract
Cdc42 GTPase is required for polarization in eukaryotic cells, but its spatial regulation is poorly understood. In Schizosaccharomyces pombe, Cdc42p is activated by Scd1p and Gef1p, two guanine-nucleotide exchange factors. Two-hybrid screening identified Hob3p as a Gef1p binding partner. Hob3p is a BAR domain-containing protein ortholog of human Bin3. Hob3p also interacts directly with Cdc42p independently of Gef1p. Hob3p, Cdc42p and Gef1p form a complex, and Hob3p facilitates Gef1p-Cdc42p interaction and activation. Hob3p forms a ring in the division area, similar to that of Gef1p. This localization requires actin polymerization and Cdc15p but is independent of the septation initiation network. Hob3p is required for the concentration of Cdc42p to the division area. The actomyosin ring contraction is slower in hob3Delta than in wild-type cells, and this contributes to its cytokinesis defect. Moreover, this report extends previous evidence that human Bin3 suppresses the cytokinesis phenotype of hob3Delta cells, showing that Bin3 can partially recover the GTP-Cdc42p level and its localization. These results suggest that Hob3p is required to recruit and activate Cdc42p at the cell division site and that this function might be conserved in other eukaryotes.
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Affiliation(s)
- Pedro M Coll
- Consejo Superior de Investigaciones Científicas (CSIC)/Departamento de Microbiología y Genética, Instituto de Microbiología Bioquímica, Universidad de Salamanca, Edificio Departamental, Salamanca 37007, Spain
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Dünkler A, Wendland J. Candida albicans Rho-type GTPase-encoding genes required for polarized cell growth and cell separation. EUKARYOTIC CELL 2007; 6:844-54. [PMID: 17351079 PMCID: PMC1899239 DOI: 10.1128/ec.00201-06] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Rho proteins are essential regulators of morphogenesis in eukaryotic cells. In this report, we investigate the role of two previously uncharacterized Rho proteins, encoded by the Candida albicans RHO3 (CaRHO3) and CaCRL1/CaRHO4 genes. The CaRHO3 gene was found to contain one intron. Promoter shutdown experiments using a MET3 promoter-controlled RHO3 revealed a strong cell polarity defect and a partially depolarized actin cytoskeleton. Hyphal growth after promoter shutdown was abolished in rho3 mutants even in the presence of a constitutively active ras1(G13V) allele, and existing germ tubes became swollen. Deletion of C. albicans RHO4 indicated that it is a nonessential gene and that rho4 mutants were phenotypically different from rho3. Two distinct phenotypes of rho4 cells were elongated cell morphology and an unexpected cell separation defect generating chains of cells. Colony morphology of crl1/rho4 resulted in a growth-dependent smooth (long cell cycle length) or wrinkled (short cell cycle length) phenotype. This phenotype was additionally dependent on the rho4 cell separation defect and was also found in a Cacht3 chitinase mutant that shows a strong cytokinesis defect. The overexpression of the endoglucanase encoding the ENG1 gene, but not CHT3, suppressed the cell separation defect of crl1/rho4 but could not suppress the cell elongation phenotype. C. albicans Crl1/Rho4 and Bnr1 both localize to septal sites in yeast and hyphal cells but not to the hyphal tip. Deletion of RHO4 and BNR1 produced similar morphological phenotypes. Based on the localization of Rho4 and on the rho4 mutant phenotype, we propose a model in which Rho4p may function as a regulator of cell polarity, breaking the initial axis of polarity found during early bud growth to promote the construction of a septum.
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Affiliation(s)
- Alexander Dünkler
- Department of Microbiology, Friedrich Schiller University, Jena, Germany
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García P, Tajadura V, García I, Sánchez Y. Role of Rho GTPases and Rho-GEFs in the regulation of cell shape and integrity in fission yeast. Yeast 2007; 23:1031-43. [PMID: 17072882 DOI: 10.1002/yea.1409] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Rho family of GTPases are highly conserved molecular switches that control some of the most fundamental processes of cell biology, including morphogenesis, vesicular transport, cell division and motility. Guanine nucleotide-exchange factors (GEFs) are directly responsible for the activation of Rho-family GTPases in response to extracellular stimuli. In fission yeast, there are seven Dbl-related GEFs and they activate six Rho-type GTPases within a particular spatio-temporal context. The failure to do so might have consequences reflected in aberrant phenotypes and in some cases lead to cell death. In this review, we briefly summarize the role of Rho GTPases and Rho-GEFs in the establishment and maintenance of cell polarity and cell integrity in Schizosaccharomyces pombe.
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Affiliation(s)
- Patricia García
- Instituto de Microbiología Bioquímica, CSIC/Universidad de Salamanca and Departamento de Microbiología y Genética, Universidad de Salamanca, Campus Miguel de Unamuno, 37007 Salamanca, Spain
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Current awareness on yeast. Yeast 2006. [DOI: 10.1002/yea.1314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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Rincón SA, Santos B, Pérez P. Fission yeast Rho5p GTPase is a functional paralogue of Rho1p that plays a role in survival of spores and stationary-phase cells. EUKARYOTIC CELL 2006; 5:435-46. [PMID: 16524899 PMCID: PMC1398058 DOI: 10.1128/ec.5.3.435-446.2006] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
The Rho GTPase family and their effectors are key regulators involved in many eukaryotic cell functions related to actin organization and polarity establishment. Schizosaccharomyces pombe Rho1p is essential, directly activates the (1,3)-beta-d-glucan synthase, and participates in regulation of cell wall growth and morphogenesis. Here we describe the characterization of the fission yeast Rho5p GTPase, highly homologous to Rho1p, sharing 86% identity and 95% similarity. Overexpression of the hyperactive allele rho5-G15V causes a morphological effect similar to that of rho1-G15V, but the penetrance is significantly lower, and overexpression of the dominant-negative allele rho5-T20N causes lysis like that of rho1-T20N. Importantly, overexpression of rho5(+) but no other rho genes is able to rescue the lethality of rho1Delta cells. Shutoff experiments indicated that Rho5p can replace Rho1p, but it is not as effective in maintaining cell wall integrity or actin organization. rho5(+) expression is hardly detected during log-phase growth but is induced under nutritional starvation conditions. rho5Delta cells are viable and do not display any defects during logarithmic growth. However, when rho1(+) expression is repressed during stationary phase, rho5Delta cells display reduced viability. Ascospores lacking Rho5p are less resistant to heat or lytic enzymes than wild-type spores. Moreover, h(90) mutant strains carrying the hyperactive rho5-G15V or the dominant-negative rho5-T20N alleles display severe ascospore formation defects. These results suggest that Rho5p functions in a way similar to, but less efficient than, Rho1p, plays a nonessential role during stationary phase, and participates in the spore wall formation.
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Affiliation(s)
- Sergio A Rincón
- Instituto Microbiología-Bioquímica, CSIC/Universidad de Salamanca, Campus Unamuno, 37007 Salamanca, Spain
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