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Varela Salgado M, Piatti S. Septin Organization and Dynamics for Budding Yeast Cytokinesis. J Fungi (Basel) 2024; 10:642. [PMID: 39330402 PMCID: PMC11433133 DOI: 10.3390/jof10090642] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2024] [Revised: 08/30/2024] [Accepted: 08/31/2024] [Indexed: 09/28/2024] Open
Abstract
Cytokinesis, the process by which the cytoplasm divides to generate two daughter cells after mitosis, is a crucial stage of the cell cycle. Successful cytokinesis must be coordinated with chromosome segregation and requires the fine orchestration of several processes, such as constriction of the actomyosin ring, membrane reorganization, and, in fungi, cell wall deposition. In Saccharomyces cerevisiae, commonly known as budding yeast, septins play a pivotal role in the control of cytokinesis by assisting the assembly of the cytokinetic machinery at the division site and controlling its activity. Yeast septins form a collar at the division site that undergoes major dynamic transitions during the cell cycle. This review discusses the functions of septins in yeast cytokinesis, their regulation and the implications of their dynamic remodelling for cell division.
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Affiliation(s)
- Maritzaida Varela Salgado
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293 Montpellier, France
| | - Simonetta Piatti
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 34293 Montpellier, France
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2
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Zuriegat Q, Abubakar YS, Wang Z, Chen M, Zhang J. Emerging Roles of Exocyst Complex in Fungi: A Review. J Fungi (Basel) 2024; 10:614. [PMID: 39330374 PMCID: PMC11433146 DOI: 10.3390/jof10090614] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2024] [Revised: 08/19/2024] [Accepted: 08/21/2024] [Indexed: 09/28/2024] Open
Abstract
The exocyst complex, an evolutionarily conserved octameric protein assembly, plays a central role in the targeted binding and fusion of vesicles at the plasma membrane. In fungal cells, this transport system is essential for polarized growth, morphogenesis, cell wall maintenance and virulence. Recent advances have greatly improved our understanding of the role and regulation of the exocyst complex in fungi. This review synthesizes these developments and focuses on the intricate interplay between the exocyst complex, specific fungal cargos and regulatory proteins. Insights into thestructure of the exocyst and its functional dynamics have revealed new dimensions of its architecture and its interactions with the cellular environment. Furthermore, the regulation of exocyst activity involves complex signaling pathways and interactions with cytoskeletal elements that are crucial for its role in vesicle trafficking. By exploring these emerging themes, this review provides a comprehensive overview of the multifaceted functions of the exocyst complex in fungal biology. Understanding these mechanisms offers potential avenues for novel therapeutic strategies against fungal pathogens and insights into the general principles of vesicle trafficking in eukaryotic cells. The review therefore highlights the importance of the exocyst complex in maintaining cellular functions and its broader implications in fungal pathogenicity and cell biology.
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Affiliation(s)
- Qussai Zuriegat
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
| | - Yakubu Saddeeq Abubakar
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
| | - Zonghua Wang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, College of Materials and Chemical Engineering, Minjiang University, Fuzhou 350108, China
| | - Meilian Chen
- Fujian Key Laboratory on Conservation and Sustainable Utilization of Marine Biodiversity, College of Materials and Chemical Engineering, Minjiang University, Fuzhou 350108, China
| | - Jun Zhang
- State Key Laboratory of Ecological Pest Control for Fujian and Taiwan Crops, Ministerial and Provincial Joint Innovation Centre for Safety Production of Cross-Strait Crops, College of Plant Protection, Fujian Agriculture and Forestry University, Fuzhou 350002, China; (Q.Z.); (Y.S.A.); (Z.W.)
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3
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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] [Key Words] [Grants] [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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Affiliation(s)
- Davinder Singh
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Yajun Liu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Yi-Hua Zhu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Sha Zhang
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Shelby Naegele
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, Ohio, United States
- Department of Biological Chemistry and Pharmacology, The Ohio State University, Columbus, Ohio, United States
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4
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Yoshii SR, Barral Y. Fission-independent compartmentalization of mitochondria during budding yeast cell division. J Cell Biol 2024; 223:e202211048. [PMID: 38180475 PMCID: PMC10783438 DOI: 10.1083/jcb.202211048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2022] [Revised: 07/14/2023] [Accepted: 12/14/2023] [Indexed: 01/06/2024] Open
Abstract
Lateral diffusion barriers compartmentalize membranes to generate polarity or asymmetrically partition membrane-associated macromolecules. Budding yeasts assemble such barriers in the endoplasmic reticulum (ER) and the outer nuclear envelope at the bud neck to retain aging factors in the mother cell and generate naïve and rejuvenated daughter cells. However, little is known about whether other organelles are similarly compartmentalized. Here, we show that the membranes of mitochondria are laterally compartmentalized at the bud neck and near the cell poles. The barriers in the inner mitochondrial membrane are constitutive, whereas those in the outer membrane form in response to stresses. The strength of mitochondrial diffusion barriers is regulated positively by spatial cues from the septin axis and negatively by retrograde (RTG) signaling. These data indicate that mitochondria are compartmentalized in a fission-independent manner. We propose that these diffusion barriers promote mitochondrial polarity and contribute to mitochondrial quality control.
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Affiliation(s)
- Saori R. Yoshii
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
- Department of Biochemistry and Molecular Biology, Graduate School and Faculty of Medicine, The University of Tokyo, Tokyo, Japan
| | - Yves Barral
- Department of Biology, Institute of Biochemistry, ETH Zürich, Zürich, Switzerland
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5
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Grupp B, Denkhaus L, Gerhardt S, Vögele M, Johnsson N, Gronemeyer T. The structure of a tetrameric septin complex reveals a hydrophobic element essential for NC-interface integrity. Commun Biol 2024; 7:48. [PMID: 38184752 PMCID: PMC10771490 DOI: 10.1038/s42003-023-05734-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/20/2023] [Indexed: 01/08/2024] Open
Abstract
The septins of the yeast Saccharomyces cerevisiae assemble into hetero-octameric rods by alternating interactions between neighboring G-domains or N- and C-termini, respectively. These rods polymerize end to end into apolar filaments, forming a ring beneath the prospective new bud that expands during the cell cycle into an hourglass structure. The hourglass finally splits during cytokinesis into a double ring. Understanding these transitions as well as the plasticity of the higher order assemblies requires a detailed knowledge of the underlying structures. Here we present the first X-ray crystal structure of a tetrameric Shs1-Cdc12-Cdc3-Cdc10 complex at a resolution of 3.2 Å. Close inspection of the NC-interfaces of this and other septin structures reveals a conserved contact motif that is essential for NC-interface integrity of yeast and human septins in vivo and in vitro. Using the tetrameric structure in combination with AlphaFold-Multimer allowed us to propose a model of the octameric septin rod.
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Affiliation(s)
- Benjamin Grupp
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Lukas Denkhaus
- Institute of Biochemistry, Albert-Ludwigs University, Freiburg, Germany
| | - Stefan Gerhardt
- Institute of Biochemistry, Albert-Ludwigs University, Freiburg, Germany
| | - Matthis Vögele
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany.
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Müller J, Furlan M, Settele D, Grupp B, Johnsson N. Transient septin sumoylation steers a Fir1-Skt5 protein complex between the split septin ring. J Cell Biol 2024; 223:e202301027. [PMID: 37938157 PMCID: PMC10631487 DOI: 10.1083/jcb.202301027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Revised: 10/05/2023] [Accepted: 10/17/2023] [Indexed: 11/09/2023] Open
Abstract
Ubiquitylation and phosphorylation control composition and architecture of the cell separation machinery in yeast and other eukaryotes. The significance of septin sumoylation on cell separation remained an enigma. Septins form an hourglass structure at the bud neck of yeast cells that transforms into a split septin double ring during mitosis. We discovered that sumoylated septins recruit the cytokinesis checkpoint protein Fir1 to the peripheral side of the septin hourglass just before its transformation into the double-ring configuration. As this transition occurs, Fir1 is released from the septins and seamlessly relocates between the split septin rings through synchronized binding to the scaffold Spa2. Fir1 binds and carries the membrane-bound Skt5 on its route to the division plane where the Fir1-Skt5 complex serves as receptor for chitin synthase III.
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Affiliation(s)
- Judith Müller
- Department of Biology, Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Monique Furlan
- Department of Biology, Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - David Settele
- Department of Biology, Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Benjamin Grupp
- Department of Biology, Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Nils Johnsson
- Department of Biology, Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
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7
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Wang K, Okada H, Wloka C, Bi E. Unraveling the mechanisms and evolution of a two-domain module in IQGAP proteins for controlling eukaryotic cytokinesis. Cell Rep 2023; 42:113510. [PMID: 38041816 PMCID: PMC10809011 DOI: 10.1016/j.celrep.2023.113510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2023] [Revised: 08/17/2023] [Accepted: 11/13/2023] [Indexed: 12/04/2023] Open
Abstract
The IQGAP family of proteins plays a crucial role in cytokinesis across diverse organisms, but the underlying mechanisms are not fully understood. In this study, we demonstrate that IQGAPs in budding yeast, fission yeast, and human cells use a two-domain module to regulate their localization as well as the assembly and disassembly of the actomyosin ring during cytokinesis. Strikingly, the calponin homology domains (CHDs) in these IQGAPs bind to distinct cellular F-actin structures with varying specificity, whereas the non-conserved domains immediately downstream of the CHDs in these IQGAPs all target the division site, but differ in timing, localization strength, and binding partners. We also demonstrate that human IQGAP3 acts in parallel to septins and myosin-IIs to mediate the role of anillin in cytokinesis. Collectively, our findings highlight the two-domain mechanism by which IQGAPs regulate cytokinesis in distantly related organisms as well as their evolutionary conservation and divergence.
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Affiliation(s)
- Kangji Wang
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Hiroki Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Carsten Wloka
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Experimental Ophthalmology, Department of Ophthalmology, Charité - Universitätsmedizin Berlin, A Corporate Member of Freie Universität, Humboldt-University, The Berlin Institute of Health, Berlin, Germany
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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Sukumar M, DeFlorio R, Pai CY, Stone DE. A member of the claudin superfamily influences formation of the front domain in pheromone-responding yeast cells. J Cell Sci 2023; 136:286256. [PMID: 36601911 DOI: 10.1242/jcs.260048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Accepted: 12/19/2022] [Indexed: 01/06/2023] Open
Abstract
Cell polarization in response to chemical gradients is important in development and homeostasis across eukaryota. Chemosensing cells orient toward or away from gradient sources by polarizing along a front-rear axis. Using the mating response of budding yeast as a model of chemotropic cell polarization, we found that Dcv1, a member of the claudin superfamily, influences front-rear polarity. Although Dcv1 localized uniformly on the plasma membrane (PM) of vegetative cells, it was confined to the rear of cells responding to pheromone, away from the pheromone receptor. dcv1Δ conferred mislocalization of sensory, polarity and trafficking proteins, as well as PM lipids. These phenotypes correlated with defects in pheromone-gradient tracking and cell fusion. We propose that Dcv1 helps demarcate the mating-specific front domain primarily by restricting PM lipid distribution.
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Affiliation(s)
- Madhushalini Sukumar
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Reagan DeFlorio
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - Chih-Yu Pai
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
| | - David E Stone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL 60607, USA
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Kunduri G, Acharya U, Acharya JK. Lipid Polarization during Cytokinesis. Cells 2022; 11:3977. [PMID: 36552741 PMCID: PMC9776629 DOI: 10.3390/cells11243977] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2022] [Revised: 12/01/2022] [Accepted: 12/02/2022] [Indexed: 12/13/2022] Open
Abstract
The plasma membrane of eukaryotic cells is composed of a large number of lipid species that are laterally segregated into functional domains as well as asymmetrically distributed between the outer and inner leaflets. Additionally, the spatial distribution and organization of these lipids dramatically change in response to various cellular states, such as cell division, differentiation, and apoptosis. Division of one cell into two daughter cells is one of the most fundamental requirements for the sustenance of growth in all living organisms. The successful completion of cytokinesis, the final stage of cell division, is critically dependent on the spatial distribution and organization of specific lipids. In this review, we discuss the properties of various lipid species associated with cytokinesis and the mechanisms involved in their polarization, including forward trafficking, endocytic recycling, local synthesis, and cortical flow models. The differences in lipid species requirements and distribution in mitotic vs. male meiotic cells will be discussed. We will concentrate on sphingolipids and phosphatidylinositols because their transbilayer organization and movement may be linked via the cytoskeleton and thus critically regulate various steps of cytokinesis.
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Affiliation(s)
- Govind Kunduri
- Cancer and Developmental Biology Laboratory, National Cancer Institute, Frederick, MD 21702, USA
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Ibanes S, El-Alaoui F, Lai-Kee-Him J, Cazevieille C, Hoh F, Lyonnais S, Bron P, Cipelletti L, Picas L, Piatti S. The Syp1/FCHo2 protein induces septin filament bundling through its intrinsically disordered domain. Cell Rep 2022; 41:111765. [PMID: 36476870 DOI: 10.1016/j.celrep.2022.111765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 09/30/2022] [Accepted: 11/10/2022] [Indexed: 12/12/2022] Open
Abstract
The septin collar of budding yeast is an ordered array of septin filaments that serves a scaffolding function for the cytokinetic machinery at the bud neck and compartmentalizes the membrane between mother and daughter cell. How septin architecture is aided by septin-binding proteins is largely unknown. Syp1 is an endocytic protein that was implicated in the timely recruitment of septins to the newly forming collar through an unknown mechanism. Using advanced microscopy and in vitro reconstitution assays, we show that Syp1 is able to align laterally and tightly pack septin filaments, thereby forming flat bundles or sheets. This property is shared by the Syp1 mammalian counterpart FCHo2, thus emphasizing conserved protein functions. Interestingly, the septin-bundling activity of Syp1 resides mainly in its intrinsically disordered region. Our data uncover the mechanism through which Syp1 promotes septin collar assembly and offer another example of functional diversity of unstructured protein domains.
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Affiliation(s)
- Sandy Ibanes
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Fatima El-Alaoui
- IRIM (Institut de Recherche en Infectiologie de Montpellier), University of Montpellier, CNRS UMR 9004, 1919 Route de Mende, 34293 Montpellier, France
| | - Joséphine Lai-Kee-Him
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Chantal Cazevieille
- COMET Electron Microscopy Platform, INM (Institute for Neurosciences of Montpellier), University of Montpellier, INSERM U 1298, 80 Rue Augustin Fliche, 34091 Montpellier, France
| | - François Hoh
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Sébastien Lyonnais
- CEMIPAI (Centre d'Etudes des Maladies Infectieuses et Pharmacologie Anti-Infectieuse), University of Montpellier, UAR 3725 CNRS, Montpellier, France
| | - Patrick Bron
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Luca Cipelletti
- L2C (Laboratoire Charles Coulomb), University of Montpellier, CNRS, Place E. Bataillon, 34095 Montpellier, France; IUF (Institut Universitaire de France), Paris, France
| | - Laura Picas
- IRIM (Institut de Recherche en Infectiologie de Montpellier), University of Montpellier, CNRS UMR 9004, 1919 Route de Mende, 34293 Montpellier, France
| | - Simonetta Piatti
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier, France.
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11
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Padovani F, Mairhörmann B, Falter-Braun P, Lengefeld J, Schmoller KM. Segmentation, tracking and cell cycle analysis of live-cell imaging data with Cell-ACDC. BMC Biol 2022; 20:174. [PMID: 35932043 PMCID: PMC9356409 DOI: 10.1186/s12915-022-01372-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 07/08/2022] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND High-throughput live-cell imaging is a powerful tool to study dynamic cellular processes in single cells but creates a bottleneck at the stage of data analysis, due to the large amount of data generated and limitations of analytical pipelines. Recent progress on deep learning dramatically improved cell segmentation and tracking. Nevertheless, manual data validation and correction is typically still required and tools spanning the complete range of image analysis are still needed. RESULTS We present Cell-ACDC, an open-source user-friendly GUI-based framework written in Python, for segmentation, tracking and cell cycle annotations. We included state-of-the-art deep learning models for single-cell segmentation of mammalian and yeast cells alongside cell tracking methods and an intuitive, semi-automated workflow for cell cycle annotation of single cells. Using Cell-ACDC, we found that mTOR activity in hematopoietic stem cells is largely independent of cell volume. By contrast, smaller cells exhibit higher p38 activity, consistent with a role of p38 in regulation of cell size. Additionally, we show that, in S. cerevisiae, histone Htb1 concentrations decrease with replicative age. CONCLUSIONS Cell-ACDC provides a framework for the application of state-of-the-art deep learning models to the analysis of live cell imaging data without programming knowledge. Furthermore, it allows for visualization and correction of segmentation and tracking errors as well as annotation of cell cycle stages. We embedded several smart algorithms that make the correction and annotation process fast and intuitive. Finally, the open-source and modularized nature of Cell-ACDC will enable simple and fast integration of new deep learning-based and traditional methods for cell segmentation, tracking, and downstream image analysis. Source code: https://github.com/SchmollerLab/Cell_ACDC.
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Affiliation(s)
- Francesco Padovani
- Institute of Functional Epigenetics (IFE), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, 85764, Munich-Neuherberg, Germany.
| | - Benedikt Mairhörmann
- Institute of Functional Epigenetics (IFE), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, 85764, Munich-Neuherberg, Germany
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, 85764, Munich-Neuherberg, Germany
| | - Pascal Falter-Braun
- Institute of Network Biology (INET), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, 85764, Munich-Neuherberg, Germany
- Microbe-Host Interactions, Faculty of Biology, Ludwig-Maximilians-University (LMU) München, 82152, Planegg-, Martinsried, Germany
| | - Jette Lengefeld
- Institute of Biotechnology, HiLIFE, University of Helsinki, Biocenter 2, P.O.Box 56 (Viikinkaari 5 D), 00014, Helsinki, Finland
- Department of Biosciences and Nutrition (BioNut), Karolinska Institutet, Huddinge, Sweden
| | - Kurt M Schmoller
- Institute of Functional Epigenetics (IFE), Molecular Targets and Therapeutics Center (MTTC), Helmholtz Center Munich, 85764, Munich-Neuherberg, Germany.
- German Center for Diabetes Research (DZD), 85764, Munich-Neuherberg, Germany.
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12
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Arbizzani F, Mavrakis M, Hoya M, Ribas JC, Brasselet S, Paoletti A, Rincon SA. Septin filament compaction into rings requires the anillin Mid2 and contractile ring constriction. Cell Rep 2022; 39:110722. [PMID: 35443188 DOI: 10.1016/j.celrep.2022.110722] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Revised: 02/10/2022] [Accepted: 03/30/2022] [Indexed: 11/19/2022] Open
Abstract
Septin filaments assemble into high-order molecular structures that associate with membranes, acting as diffusion barriers and scaffold proteins crucial for many cellular processes. How septin filaments organize in such structures is still not understood. Here, we used fission yeast to explore septin filament organization during cell division and its cell cycle regulation. Live-imaging and polarization microscopy analysis uncovered that septin filaments are initially recruited as a diffuse meshwork surrounding the acto-myosin contractile ring (CR) in anaphase, which undergoes compaction into two rings when CR constriction is initiated. We found that the anillin-like protein Mid2 is necessary to promote this compaction step, possibly acting as a bundler for septin filaments. Moreover, Mid2-driven septin compaction requires inputs from the septation initiation network as well as CR constriction and the β(1,3)-glucan synthase Bgs1. This work highlights that anillin-mediated septin ring assembly is under strict cell cycle control.
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Affiliation(s)
| | - Manos Mavrakis
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France
| | - Marta Hoya
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, 37007 Salamanca, Spain
| | - Juan Carlos Ribas
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, 37007 Salamanca, Spain
| | - Sophie Brasselet
- Aix Marseille Université, CNRS, Centrale Marseille, Institut Fresnel, UMR 7249, 13013 Marseille, France
| | - Anne Paoletti
- Institut Curie, PSL University, CNRS UMR 144, 75005 Paris, France.
| | - Sergio A Rincon
- Instituto de Biología Funcional y Genómica and Departamento de Microbiología y Genética, Consejo Superior de Investigaciones Científicas (CSIC)/Universidad de Salamanca, 37007 Salamanca, Spain.
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13
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Role of the anillin-like protein in growth of Cryptococcus neoformans at human host temperature. Fungal Genet Biol 2022; 160:103697. [DOI: 10.1016/j.fgb.2022.103697] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 04/16/2022] [Accepted: 04/18/2022] [Indexed: 11/23/2022]
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14
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Moyano-Rodríguez Y, Vaquero D, Vilalta-Castany O, Foltman M, Sanchez-Diaz A, Queralt E. PP2A-Cdc55 phosphatase regulates actomyosin ring contraction and septum formation during cytokinesis. Cell Mol Life Sci 2022; 79:165. [PMID: 35230542 PMCID: PMC8888506 DOI: 10.1007/s00018-022-04209-1] [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: 09/01/2021] [Revised: 02/11/2022] [Accepted: 02/13/2022] [Indexed: 11/03/2022]
Abstract
Eukaryotic cells divide and separate all their components after chromosome segregation by a process called cytokinesis to complete cell division. Cytokinesis is highly regulated by the recruitment of the components to the division site and through post-translational modifications such as phosphorylations. The budding yeast mitotic kinases Cdc28-Clb2, Cdc5, and Dbf2-Mob1 phosphorylate several cytokinetic proteins contributing to the regulation of cytokinesis. The PP2A-Cdc55 phosphatase regulates mitosis counteracting Cdk1- and Cdc5-dependent phosphorylation. This prompted us to propose that PP2A-Cdc55 could also be counteracting the mitotic kinases during cytokinesis. Here we show that in the absence of Cdc55, AMR contraction and the primary septum formation occur asymmetrically to one side of the bud neck supporting a role for PP2A-Cdc55 in cytokinesis regulation. In addition, by in vivo and in vitro assays, we show that PP2A-Cdc55 dephosphorylates the chitin synthase II (Chs2 in budding yeast) a component of the Ingression Progression Complexes (IPCs) involved in cytokinesis. Interestingly, the non-phosphorylable version of Chs2 rescues the asymmetric AMR contraction and the defective septa formation observed in cdc55∆ mutant cells. Therefore, timely dephosphorylation of the Chs2 by PP2A-Cdc55 is crucial for proper actomyosin ring contraction. These findings reveal a new mechanism of cytokinesis regulation by the PP2A-Cdc55 phosphatase and extend our knowledge of the involvement of multiple phosphatases during cytokinesis.
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Affiliation(s)
- Yolanda Moyano-Rodríguez
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain
| | - David Vaquero
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain.,Instituto de Biomedicina de Valencia (IBV-CSIC), C/ Jaume Roig 11, Valencia, Spain
| | - Odena Vilalta-Castany
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain
| | - Magdalena Foltman
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain.,Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Alberto Sanchez-Diaz
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain.,Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Ethel Queralt
- Cell Cycle Group, Institut d'Investigació Biomèdica de Bellvitge (IDIBELL), Av. Gran Via de L'Hospitalet 199-203, L'Hospitalet de Llobregat, Barcelona, Spain. .,Instituto de Biomedicina de Valencia (IBV-CSIC), C/ Jaume Roig 11, Valencia, Spain.
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15
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Zheng S, Zheng B, Liu Z, Ma X, Liu X, Yao X, Wei W, Fu C. The Cdc42 GTPase activating protein Rga6 promotes the cortical localization of Septin. J Cell Sci 2022; 135:274388. [DOI: 10.1242/jcs.259228] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2021] [Accepted: 01/06/2022] [Indexed: 11/20/2022] Open
Abstract
Septins are a family of filament-forming GTP-binding proteins that regulate fundamental cellular activities such as cytokinesis and cell polarity. In general, Septin filaments function as barriers and scaffolds on the cell cortex. However, little is known about the mechanism that governs the recruitment and localization of the Septin complex to the cell cortex. Here, we identified the Cdc42 GTPase activating protein Rga6 as a key protein involved in promoting the localization of the Septin complex to the cell cortex in the fission yeast Schizosaccharomyces pombe. Rga6 interacts with the Septin complex and partially colocalizes with the Septin complex on the cell cortex. Live-cell microscopic analysis further showed Septin enrichment at the cortical regions adjacent to the growing cell tip. The Septin enrichment likely plays a crucial role in confining active Cdc42 to the growing cell tip. Hence, our findings support a model that Rga6 regulates polarized cell growth partly through promoting targeted localization of the Septin complex on the cell cortex.
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Affiliation(s)
- Shengnan Zheng
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Biyu Zheng
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Zhenbang Liu
- Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Xiaopeng Ma
- Department of General Surgery, the First Affiliated Hospital of USTC, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, 230001, PR China
| | - Xing Liu
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Xuebiao Yao
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Wenfan Wei
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
| | - Chuanhai Fu
- Ministry of Education Key Laboratory for Cellular Dynamics, CAS Center for Excellence in Molecular Cell Sciences, Hefei National Laboratory for Physical Sciences at the Microscale, School of Life Sciences, Division of Life Sciences and Medicine, University of Science and Technology of China, 230027 Hefei, P.R. China
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16
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Vial A, Taveneau C, Costa L, Chauvin B, Nasrallah H, Godefroy C, Dosset P, Isambert H, Ngo KX, Mangenot S, Levy D, Bertin A, Milhiet PE. Correlative AFM and fluorescence imaging demonstrate nanoscale membrane remodeling and ring-like and tubular structure formation by septins. NANOSCALE 2021; 13:12484-12493. [PMID: 34225356 DOI: 10.1039/d1nr01978c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Septins are ubiquitous cytoskeletal filaments that interact with the inner plasma membrane and are essential for cell division in eukaryotes. In cellular contexts, septins are often localized at micrometric Gaussian curvatures, where they assemble onto ring-like structures. The behavior of budding yeast septins depends on their specific interaction with inositol phospholipids, enriched at the inner leaflet of the plasma membrane. Septin filaments are built from the non-polar self-assembly of short rods into filaments. However, the molecular mechanisms regulating the interplay with the inner plasma membrane and the resulting interaction with specific curvatures are not fully understood. In this report, we have imaged dynamical molecular assemblies of budding yeast septins on PIP2-containing supported lipid bilayers using a combination of high-speed AFM and correlative AFM-fluorescence microscopy. Our results clearly demonstrate that septins are able to bind to flat supported lipid bilayers and thereafter induce the remodeling of membranes. Short septin rods (octamers subunits) can indeed destabilize supported lipid bilayers and reshape the membrane to form 3D structures such as rings and tubes, demonstrating that long filaments are not necessary for septin-induced membrane buckling.
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Affiliation(s)
- Anthony Vial
- Centre de Biochimie Structurale (CBS), Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France.
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17
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Spiliotis ET, McMurray MA. Masters of asymmetry - lessons and perspectives from 50 years of septins. Mol Biol Cell 2021; 31:2289-2297. [PMID: 32991244 PMCID: PMC7851956 DOI: 10.1091/mbc.e19-11-0648] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Septins are a unique family of GTPases, which were discovered 50 years ago as essential genes for the asymmetric cell shape and division of budding yeast. Septins assemble into filamentous nonpolar polymers, which associate with distinct membrane macrodomains and subpopulations of actin filaments and microtubules. While structurally a cytoskeleton-like element, septins function predominantly as spatial regulators of protein localization and interactions. Septin scaffolds and barriers have provided a long-standing paradigm for the generation and maintenance of asymmetry in cell membranes. Septins also promote asymmetry by regulating the spatial organization of the actin and microtubule cytoskeleton, and biasing the directionality of membrane traffic. In this 50th anniversary perspective, we highlight how septins have conserved and adapted their roles as effectors of membrane and cytoplasmic asymmetry across fungi and animals. We conclude by outlining principles of septin function as a module of symmetry breaking, which alongside the monomeric small GTPases provides a core mechanism for the biogenesis of molecular asymmetry and cell polarity.
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Affiliation(s)
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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18
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Abstract
Septins are an integral component of the cytoskeleton, assembling into higher-order oligomers and filamentous polymers that associate with actin filaments, microtubules and membranes. Here, we review septin interactions with actin and microtubules, and septin-mediated regulation of the organization and dynamics of these cytoskeletal networks, which is critical for cellular morphogenesis. We discuss how actomyosin-associated septins function in cytokinesis, cell migration and host defense against pathogens. We highlight newly emerged roles of septins at the interface of microtubules and membranes with molecular motors, which point to a 'septin code' for the regulation of membrane traffic. Additionally, we revisit the functions of microtubule-associated septins in mitosis and meiosis. In sum, septins comprise a unique module of cytoskeletal regulators that are spatially and functionally specialized and have properties of bona fide actin-binding and microtubule-associated proteins. With many questions still outstanding, the study of septins will continue to provide new insights into fundamental problems of cytoskeletal organization and function.
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19
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Mela A, Momany M. Septins coordinate cell wall integrity and lipid metabolism in a sphingolipid-dependent process. J Cell Sci 2021; 135:256543. [PMID: 33912961 DOI: 10.1242/jcs.258336] [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: 12/17/2020] [Accepted: 12/31/2020] [Indexed: 01/09/2023] Open
Abstract
Septins colocalize with membrane sterol-rich regions and facilitate recruitment of cell wall synthases during wall remodeling. We show that null mutants missing an Aspergillus nidulans core septin present in hexamers and octamers (ΔaspAcdc11, ΔaspBcdc3 or ΔaspCcdc12) are sensitive to multiple cell wall-disturbing agents that activate the cell wall integrity MAPK pathway. The null mutant missing the octamer-exclusive core septin (ΔaspDcdc10) showed similar sensitivity, but only to a single cell wall-disturbing agent and the null mutant missing the noncore septin (ΔaspE) showed only very mild sensitivity to a different single agent. Core septin mutants showed changes in wall polysaccharide composition and chitin synthase localization. Mutants missing any of the five septins resisted ergosterol-disrupting agents. Hexamer mutants showed increased sensitivity to sphingolipid-disrupting agents. Core septins mislocalized after treatment with sphingolipid-disrupting agents, but not after ergosterol-disrupting agents. Our data suggest that the core septins are involved in cell wall integrity signaling, that all five septins are involved in monitoring ergosterol metabolism, that the hexamer septins are required for sphingolipid metabolism and that septins require sphingolipids to coordinate the cell wall integrity response.
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Affiliation(s)
- Alexander Mela
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
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20
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Wang J, Li L, Ming Z, Wu L, Yan L. Crystal Structure of the Epo1-Bem3 Complex for Bud Growth. Int J Mol Sci 2021; 22:ijms22083812. [PMID: 33917059 PMCID: PMC8067709 DOI: 10.3390/ijms22083812] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 03/30/2021] [Accepted: 04/04/2021] [Indexed: 02/05/2023] Open
Abstract
Tubules of the endoplasmic reticulum (ER) spread into the buds of yeast by an actin-based mechanism and, upon entry, become attached to the polarisome, a proteinaceous micro-compartment below the tip of the bud. The minimal tether between polarisome and cortical ER is formed by a protein complex consisting of Epo1, a member of the polarisome, Scs2, a membrane protein of the ER and Cdc42 guanosine triphosphatase-activating protein Bem3. Here, we report the crystal structure of a complex between Epo1 and Bem3. In addition, we characterize through the hydrogen/deuterium (H/D) exchange assay the interface between Scs2 and Epo1. Our findings provide a first structural insight into the molecular architecture of the link between cortical ER and the polarisome.
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Affiliation(s)
- Jin Wang
- State Key Laboratory of Biotherapy, West China Hospital, Collaborative Innovation Center for Biotherapy, Sichuan University, Chengdu 610041, China; (J.W.); (L.L.)
- Laboratory of Structural Biology and MOE Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing 100084, China
| | - Lei Li
- State Key Laboratory of Biotherapy, West China Hospital, Collaborative Innovation Center for Biotherapy, Sichuan University, Chengdu 610041, China; (J.W.); (L.L.)
| | - Zhenhua Ming
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-Bioresources, College of Life Science and Technology, Guangxi University, Nanning 530000, China;
| | - Lijie Wu
- iHuman Institute, ShanghaiTech University, Shanghai 201210, China;
| | - Liming Yan
- Laboratory of Structural Biology and MOE Laboratory of Protein Science, School of Medicine, Tsinghua University, Beijing 100084, China
- Correspondence:
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21
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Abstract
In bacteria, a condensed structure of FtsZ (Z-ring) recruits cell division machinery at the midcell, and Z-ring formation is discouraged over the chromosome by a poorly understood phenomenon called nucleoid occlusion. In B. subtilis, nucleoid occlusion has been reported to be mediated, at least in part, by the DNA-membrane bridging protein, Noc. Bacteria that divide by binary fission form FtsZ rings at the geometric midpoint of the cell between the bulk of the replicated nucleoids. In Bacillus subtilis, the DNA- and membrane-binding Noc protein is thought to participate in nucleoid occlusion by preventing FtsZ rings from forming over the chromosome. To explore the role of Noc, we used time-lapse fluorescence microscopy to monitor FtsZ and the nucleoid of cells growing in microfluidic channels. Our data show that Noc does not prevent de novo FtsZ ring formation over the chromosome nor does Noc control cell division site selection. Instead, Noc corrals FtsZ at the cytokinetic ring and reduces migration of protofilaments over the chromosome to the future site of cell division. Moreover, we show that FtsZ protofilaments travel due to a local reduction in ZapA association, and the diffuse FtsZ rings observed in the Noc mutant can be suppressed by ZapA overexpression. Thus, Noc sterically hinders FtsZ migration away from the Z-ring during cytokinesis and retains FtsZ at the postdivisional polar site for full disassembly by the Min system.
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22
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Takagi J, Cho C, Duvalyan A, Yan Y, Halloran M, Hanson-Smith V, Thorner J, Finnigan GC. Reconstructed evolutionary history of the yeast septins Cdc11 and Shs1. G3-GENES GENOMES GENETICS 2021; 11:6025175. [PMID: 33561226 PMCID: PMC7849910 DOI: 10.1093/g3journal/jkaa006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/13/2020] [Indexed: 11/21/2022]
Abstract
Septins are GTP-binding proteins conserved across metazoans. They can polymerize into extended filaments and, hence, are considered a component of the cytoskeleton. The number of individual septins varies across the tree of life—yeast (Saccharomyces cerevisiae) has seven distinct subunits, a nematode (Caenorhabditis elegans) has two, and humans have 13. However, the overall geometric unit (an apolar hetero-octameric protomer and filaments assembled there from) has been conserved. To understand septin evolutionary variation, we focused on a related pair of yeast subunits (Cdc11 and Shs1) that appear to have arisen from gene duplication within the fungal clade. Either Cdc11 or Shs1 occupies the terminal position within a hetero-octamer, yet Cdc11 is essential for septin function and cell viability, whereas Shs1 is not. To discern the molecular basis of this divergence, we utilized ancestral gene reconstruction to predict, synthesize, and experimentally examine the most recent common ancestor (“Anc.11-S”) of Cdc11 and Shs1. Anc.11-S was able to occupy the terminal position within an octamer, just like the modern subunits. Although Anc.11-S supplied many of the known functions of Cdc11, it was unable to replace the distinct function(s) of Shs1. To further evaluate the history of Shs1, additional intermediates along a proposed trajectory from Anc.11-S to yeast Shs1 were generated and tested. We demonstrate that multiple events contributed to the current properties of Shs1: (1) loss of Shs1–Shs1 self-association early after duplication, (2) co-evolution of heterotypic Cdc11–Shs1 interaction between neighboring hetero-octamers, and (3) eventual repurposing and acquisition of novel function(s) for its C-terminal extension domain. Thus, a pair of duplicated proteins, despite constraints imposed by assembly into a highly conserved multi-subunit structure, could evolve new functionality via a complex evolutionary pathway.
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Affiliation(s)
- Julie Takagi
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Christina Cho
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Angela Duvalyan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Yao Yan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Megan Halloran
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Victor Hanson-Smith
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Jeremy Thorner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Gregory C Finnigan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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23
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Wang K, Okada H, Bi E. Comparative Analysis of the Roles of Non-muscle Myosin-IIs in Cytokinesis in Budding Yeast, Fission Yeast, and Mammalian Cells. Front Cell Dev Biol 2020; 8:593400. [PMID: 33330476 PMCID: PMC7710916 DOI: 10.3389/fcell.2020.593400] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 10/30/2020] [Indexed: 12/31/2022] Open
Abstract
The contractile ring, which plays critical roles in cytokinesis in fungal and animal cells, has fascinated biologists for decades. However, the basic question of how the non-muscle myosin-II and actin filaments are assembled into a ring structure to drive cytokinesis remains poorly understood. It is even more mysterious why and how the budding yeast Saccharomyces cerevisiae, the fission yeast Schizosaccharomyces pombe, and humans construct the ring structure with one, two, and three myosin-II isoforms, respectively. Here, we provide a comparative analysis of the roles of the non-muscle myosin-IIs in cytokinesis in these three model systems, with the goal of defining the common and unique features and highlighting the major questions regarding this family of proteins.
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Affiliation(s)
- Kangji Wang
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Hiroki Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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24
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Carim SC, Kechad A, Hickson GRX. Animal Cell Cytokinesis: The Rho-Dependent Actomyosin-Anilloseptin Contractile Ring as a Membrane Microdomain Gathering, Compressing, and Sorting Machine. Front Cell Dev Biol 2020; 8:575226. [PMID: 33117802 PMCID: PMC7575755 DOI: 10.3389/fcell.2020.575226] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2020] [Accepted: 09/07/2020] [Indexed: 12/19/2022] Open
Abstract
Cytokinesis is the last step of cell division that partitions the cellular organelles and cytoplasm of one cell into two. In animal cells, cytokinesis requires Rho-GTPase-dependent assembly of F-actin and myosin II (actomyosin) to form an equatorial contractile ring (CR) that bisects the cell. Despite 50 years of research, the precise mechanisms of CR assembly, tension generation and closure remain elusive. This hypothesis article considers a holistic view of the CR that, in addition to actomyosin, includes another Rho-dependent cytoskeletal sub-network containing the scaffold protein, Anillin, and septin filaments (collectively termed anillo-septin). We synthesize evidence from our prior work in Drosophila S2 cells that actomyosin and anillo-septin form separable networks that are independently anchored to the plasma membrane. This latter realization leads to a simple conceptual model in which CR assembly and closure depend upon the micro-management of the membrane microdomains to which actomyosin and anillo-septin sub-networks are attached. During CR assembly, actomyosin contractility gathers and compresses its underlying membrane microdomain attachment sites. These microdomains resist this compression, which builds tension. During CR closure, membrane microdomains are transferred from the actomyosin sub-network to the anillo-septin sub-network, with which they flow out of the CR as it advances. This relative outflow of membrane microdomains regulates tension, reduces the circumference of the CR and promotes actomyosin disassembly all at the same time. According to this hypothesis, the metazoan CR can be viewed as a membrane microdomain gathering, compressing and sorting machine that intrinsically buffers its own tension through coordination of actomyosin contractility and anillo-septin-membrane relative outflow, all controlled by Rho. Central to this model is the abandonment of the dogmatic view that the plasma membrane is always readily deformable by the underlying cytoskeleton. Rather, the membrane resists compression to build tension. The notion that the CR might generate tension through resistance to compression of its own membrane microdomain attachment sites, can account for numerous otherwise puzzling observations and warrants further investigation using multiple systems and methods.
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Affiliation(s)
- Sabrya C. Carim
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Amel Kechad
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
| | - Gilles R. X. Hickson
- CHU Sainte-Justine Research Center, Université de Montréal, Montréal, QC, Canada
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, Montréal, QC, Canada
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25
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Farkašovský M. Septin architecture and function in budding yeast. Biol Chem 2020; 401:903-919. [PMID: 31913844 DOI: 10.1515/hsz-2019-0401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/28/2019] [Indexed: 01/22/2023]
Abstract
The septins constitute a conserved family of guanosine phosphate-binding and filament-forming proteins widespread across eukaryotic species. Septins appear to have two principal functions. One is to form a cortical diffusion barrier, like the septin collar at the bud neck of Saccharomyces cerevisiae, which prevents movement of membrane-associated proteins between the mother and daughter cells. The second is to serve as a polymeric scaffold for recruiting the proteins required for critical cellular processes to particular subcellular areas. In the last decade, structural information about the different levels of septin organization has appeared, but crucial structural determinants and factors responsible for septin assembly remain largely unknown. This review highlights recent findings on the architecture and function of septins and their remodeling with an emphasis on mitotically dividing budding yeasts.
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Affiliation(s)
- Marian Farkašovský
- Department of Biochemistry and Protein Structure, Institute of Molecular Biology SAS, Dubravska cesta 21, 84551 Bratislava, Slovak Republic
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26
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Chollet J, Dünkler A, Bäuerle A, Vivero-Pol L, Mulaw MA, Gronemeyer T, Johnsson N. Cdc24 interacts with septins to create a positive feedback loop during bud site assembly in yeast. J Cell Sci 2020; 133:jcs240283. [PMID: 32327559 DOI: 10.1242/jcs.240283] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2019] [Accepted: 04/08/2020] [Indexed: 01/04/2023] Open
Abstract
Yeast cells select the position of their new bud at the beginning of each cell cycle. The recruitment of septins to this prospective bud site is one of the critical events in a complex assembly pathway that culminates in the outgrowth of a new daughter cell. During recruitment, septin rods follow the high concentration of Cdc42GTP that is generated by the focused localization of the Cdc42 guanine-nucleotide-exchange factor Cdc24. We show that, shortly before budding, Cdc24 not only activates Cdc42 but also transiently interacts with Cdc11, the septin subunit that caps both ends of the septin rods. Mutations in Cdc24 that reduce affinity to Cdc11 impair septin recruitment and decrease the stability of the polarity patch. The interaction between septins and Cdc24 thus reinforces bud assembly at sites where septin structures are formed. Once the septins polymerize to form the septin ring, Cdc24 is found at the cortex of the bud and directs further outgrowth from this position.
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Affiliation(s)
- Julian Chollet
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Alexander Dünkler
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Anne Bäuerle
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Laura Vivero-Pol
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Medhanie A Mulaw
- Comprehensive Cancer Center Ulm, Institute of Experimental Cancer Research, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Department of Biology, Ulm University, James-Franck-Ring N27, D-89081 Ulm, Germany
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27
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Cytokinesis: An Anillin–RhoGEF Module Sets the Stage for Septin Double Ring Assembly. Curr Biol 2020; 30:R347-R349. [DOI: 10.1016/j.cub.2020.02.035] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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28
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Chen X, Wang K, Svitkina T, Bi E. Critical Roles of a RhoGEF-Anillin Module in Septin Architectural Remodeling during Cytokinesis. Curr Biol 2020; 30:1477-1490.e3. [PMID: 32197082 DOI: 10.1016/j.cub.2020.02.023] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 12/23/2019] [Accepted: 02/10/2020] [Indexed: 12/24/2022]
Abstract
How septin architecture is remodeled from an hourglass to a double ring during cytokinesis in fungal and animal cells remains unknown. Here, we show that during the hourglass-to-double-ring transition in budding yeast, septins acquire a "zonal architecture" in which paired septin filaments that are organized along the mother-bud axis associate with circumferential single septin filaments, the Rho guanine-nucleotide-exchange factor (RhoGEF) Bud3, and the anillin-like protein Bud4 exclusively at the outer zones and with myosin-II filaments in the middle zone. Deletion of Bud3 or its Bud4-interacting domain, but not its RhoGEF domain, leads to a complete loss of the single filaments, whereas deletion of Bud4 or its Bud3-interacting domain destabilizes the transitional hourglass, especially at the mother side, with partial loss of both filament types. Deletion of Bud3 and Bud4 together further weakens the transitional structure and abolishes the double ring formation while causing no obvious defect in actomyosin ring constriction. This and further analyses suggest that Bud3 stabilizes the single filaments, whereas Bud4 strengthens the interaction between the paired and single filaments at the outer zones of the transitional hourglass, as well as in the double ring. This study reveals a striking zonal architecture for the transitional hourglass that pre-patterns two cytokinetic structures-a septin double ring and an actomyosin ring-and also defines the essential roles of a RhoGEF-anillin module in septin architectural remodeling during cytokinesis at the filament level.
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Affiliation(s)
- Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Kangji Wang
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Tatyana Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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Yeast as a Model to Understand Actin-Mediated Cellular Functions in Mammals-Illustrated with Four Actin Cytoskeleton Proteins. Cells 2020; 9:cells9030672. [PMID: 32164332 PMCID: PMC7140605 DOI: 10.3390/cells9030672] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 03/05/2020] [Accepted: 03/05/2020] [Indexed: 12/31/2022] Open
Abstract
The budding yeast Saccharomyces cerevisiae has an actin cytoskeleton that comprises a set of protein components analogous to those found in the actin cytoskeletons of higher eukaryotes. Furthermore, the actin cytoskeletons of S. cerevisiae and of higher eukaryotes have some similar physiological roles. The genetic tractability of budding yeast and the availability of a stable haploid cell type facilitates the application of molecular genetic approaches to assign functions to the various actin cytoskeleton components. This has provided information that is in general complementary to that provided by studies of the equivalent proteins of higher eukaryotes and hence has enabled a more complete view of the role of these proteins. Several human functional homologues of yeast actin effectors are implicated in diseases. A better understanding of the molecular mechanisms underpinning the functions of these proteins is critical to develop improved therapeutic strategies. In this article we chose as examples four evolutionarily conserved proteins that associate with the actin cytoskeleton: (1) yeast Hof1p/mammalian PSTPIP1, (2) yeast Rvs167p/mammalian BIN1, (3) yeast eEF1A/eEF1A1 and eEF1A2 and (4) yeast Yih1p/mammalian IMPACT. We compare the knowledge on the functions of these actin cytoskeleton-associated proteins that has arisen from studies of their homologues in yeast with information that has been obtained from in vivo studies using live animals or in vitro studies using cultured animal cell lines.
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30
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Cytokinesis in Eukaryotic Cells: The Furrow Complexity at a Glance. Cells 2020; 9:cells9020271. [PMID: 31979090 PMCID: PMC7072619 DOI: 10.3390/cells9020271] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 01/17/2020] [Accepted: 01/20/2020] [Indexed: 12/31/2022] Open
Abstract
The duplication cycle is the fascinating process that, starting from a cell, results in the formation of two daughter cells and it is essential for life. Cytokinesis is the final step of the cell cycle, it is a very complex phase, and is a concert of forces, remodeling, trafficking, and cell signaling. All of the steps of cell division must be properly coordinated with each other to faithfully segregate the genetic material and this task is fundamental for generating viable cells. Given the importance of this process, molecular pathways and proteins that are involved in cytokinesis are conserved from yeast to humans. In this review, we describe symmetric and asymmetric cell division in animal cell and in a model organism, budding yeast. In addition, we illustrate the surveillance mechanisms that ensure a proper cell division and discuss the connections with normal cell proliferation and organs development and with the occurrence of human diseases.
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31
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Wang X, Tian W, Banh BT, Statler BM, Liang J, Stone DE. Mating yeast cells use an intrinsic polarity site to assemble a pheromone-gradient tracking machine. J Cell Biol 2019; 218:3730-3752. [PMID: 31570500 PMCID: PMC6829655 DOI: 10.1083/jcb.201901155] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 06/06/2019] [Accepted: 08/08/2019] [Indexed: 12/12/2022] Open
Abstract
The mating of budding yeast depends on chemotropism, a fundamental cellular process. The two yeast mating types secrete peptide pheromones that bind to GPCRs on cells of the opposite type. Cells find and contact a partner by determining the direction of the pheromone source and polarizing their growth toward it. Actin-directed secretion to the chemotropic growth site (CS) generates a mating projection. When pheromone-stimulated cells are unable to sense a gradient, they form mating projections where they would have budded in the next cell cycle, at a position called the default polarity site (DS). Numerous models have been proposed to explain yeast gradient sensing, but none address how cells reliably switch from the intrinsically determined DS to the gradient-aligned CS, despite a weak spatial signal. Here we demonstrate that, in mating cells, the initially uniform receptor and G protein first polarize to the DS, then redistribute along the plasma membrane until they reach the CS. Our data indicate that signaling, polarity, and trafficking proteins localize to the DS during assembly of what we call the gradient tracking machine (GTM). Differential activation of the receptor triggers feedback mechanisms that bias exocytosis upgradient and endocytosis downgradient, thus enabling redistribution of the GTM toward the pheromone source. The GTM stabilizes when the receptor peak centers at the CS and the endocytic machinery surrounds it. A computational model simulates GTM tracking and stabilization and correctly predicts that its assembly at a single site contributes to mating fidelity.
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Affiliation(s)
- Xin Wang
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL
| | - Wei Tian
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL
| | - Bryan T Banh
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL
| | | | - Jie Liang
- Department of Bioengineering, University of Illinois at Chicago, Chicago, IL
| | - David E Stone
- Department of Biological Sciences, University of Illinois at Chicago, Chicago, IL
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32
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Kumar H, Pushpa K, Kumari A, Verma K, Pergu R, Mylavarapu SVS. The exocyst complex and Rab5 are required for abscission by localizing ESCRT III subunits to the cytokinetic bridge. J Cell Sci 2019; 132:jcs226001. [PMID: 31221728 PMCID: PMC6679584 DOI: 10.1242/jcs.226001] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2018] [Accepted: 06/14/2019] [Indexed: 01/26/2023] Open
Abstract
Cytokinesis is the final step of cell division following chromosome segregation that generates two daughter cells. The conserved exocyst complex is required for scission of the intercellular cytokinetic bridge, although the molecular mechanisms it employs in this process are unclear. We identify and validate the early endocytic GTPase Rab5 as interacting with the exocyst complex in mammalian cells. Rab5 localizes in the cytokinetic bridge and on the midbody ring in a manner similar to the exocyst complex. Depletion of Rab5 led to delayed abscission. Caenorhabditis elegans orthologs of both exocyst complex subunits and Rab5 localize along the cleavage furrow and are required for cytokinesis in early embryos. Cytokinetic cells depleted of either Rab5 or the exocyst subunits Exoc3 and Exoc4 showed impaired deposition of the endosomal sorting complexes required for transport (ESCRT) III subunits CHMP2B and/or CHMP4B near the midbody ring. The study reveals an evolutionarily conserved role for the early endocytic marker Rab5 in cytokinetic abscission. In addition, it uncovers a key requirement of the exocyst and Rab5 for the delivery of components of the membrane-severing ESCRT III machinery to complete cytokinesis.
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Affiliation(s)
- Harsh Kumar
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
- Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Kumari Pushpa
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Amrita Kumari
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
- Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Kuldeep Verma
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
| | - Rajaiah Pergu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
- Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
| | - Sivaram V S Mylavarapu
- Laboratory of Cellular Dynamics, Regional Centre for Biotechnology, NCR Biotech Science Cluster, 3rd Milestone Faridabad-Gurgaon Expressway, Faridabad, Haryana 121001, India
- Manipal Academy of Higher Education, Manipal, Karnataka 576104, India
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33
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Karasmanis EP, Hwang D, Nakos K, Bowen JR, Angelis D, Spiliotis ET. A Septin Double Ring Controls the Spatiotemporal Organization of the ESCRT Machinery in Cytokinetic Abscission. Curr Biol 2019; 29:2174-2182.e7. [PMID: 31204162 DOI: 10.1016/j.cub.2019.05.050] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 03/29/2019] [Accepted: 05/20/2019] [Indexed: 01/01/2023]
Abstract
Abscission is the terminal step of mitosis that physically separates two daughter cells [1, 2]. Abscission requires the endocytic sorting complex required for transport (ESCRT), a molecular machinery of multiple subcomplexes (ESCRT-I/II/III) that promotes membrane remodeling and scission [3-5]. Recruitment of ESCRT-I/II complexes to the midbody of telophase cells initiates ESCRT-III assembly into two rings, which subsequently expand into helices and spirals that narrow down to the incipient site of abscission [6-8]. ESCRT-III assembly is highly dynamic and spatiotemporally ordered, but the underlying mechanisms are poorly understood. Here, we report that, after cleavage furrow closure, septins form a membrane-bound double ring that controls the organization and function of ESCRT-III. The septin double ring demarcates the sites of ESCRT-III assembly into rings and disassembles before ESCRT-III rings expand into helices and spirals. We show that septin 9 (SEPT9) depletion, which abrogates abscission, impairs recruitment of VPS25 (ESCRT-II) and CHMP6 (ESCRT-III). Strikingly, ESCRT-III subunits (CHMP4B and CHMP2A/B) accumulate to the midbody, but they are highly disorganized, failing to form symmetric rings and to expand laterally into the cone-shaped helices and spirals of abscission. We found that SEPT9 interacts directly with the ubiquitin E2 variant (UEV) domain of ESCRT-I protein TSG101 through two N-terminal PTAP motifs, which are required for the recruitment of VPS25 and CHMP6, and the spatial organization of ESCRT-III (CHMP4B and CHMP2B) into functional rings. These results reveal that septins function in the ESCRT-I-ESCRT-II-CHMP6 pathway of ESCRT-III assembly and provide a framework for the spatiotemporal control of the ESCRT machinery of cytokinetic abscission.
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Affiliation(s)
- Eva P Karasmanis
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Daniel Hwang
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | | | - Jonathan R Bowen
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Dimitrios Angelis
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA.
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34
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Distinct segregation patterns of yeast cell-peripheral proteins uncovered by a method for protein segregatome analysis. Proc Natl Acad Sci U S A 2019; 116:8909-8918. [PMID: 30975753 DOI: 10.1073/pnas.1819715116] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Protein segregation contributes to various cellular processes such as polarization, differentiation, and aging. However, the difficulty in global determination of protein segregation hampers our understanding of its mechanisms and physiological roles. Here, by developing a quantitative proteomics technique, we globally monitored segregation of preexisting and newly synthesized proteins during cell division of budding yeast, and identified crucial domains that determine the segregation of cell-peripheral proteins. Remarkably, the proteomic and subsequent microscopic analyses demonstrated that the flow through the bud neck of the proteins that harbor both endoplasmic reticulum (ER) membrane-spanning and plasma membrane (PM)-binding domains is not restricted by the previously suggested ER membrane or PM diffusion barriers but by septin-mediated partitioning of the PM-associated ER (pmaER). Furthermore, the proteomic analysis revealed that although the PM-spanning t-SNARE Sso2 was retained in mother cells, its paralog Sso1 unexpectedly showed symmetric localization. We found that the transport of Sso1 to buds was required for enhancement of polarized cell growth and resistance to cell-wall stress. Taken together, these data resolve long-standing questions about septin-mediated compartmentalization of the cell periphery, and provide new mechanistic insights into the segregation of cell-periphery proteins and their cellular functions.
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35
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Okada H, Wloka C, Wu JQ, Bi E. Distinct Roles of Myosin-II Isoforms in Cytokinesis under Normal and Stressed Conditions. iScience 2019; 14:69-87. [PMID: 30928696 PMCID: PMC6441717 DOI: 10.1016/j.isci.2019.03.014] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Revised: 01/30/2019] [Accepted: 03/12/2019] [Indexed: 12/31/2022] Open
Abstract
To address the question of why more than one myosin-II isoform is expressed in a single cell to drive cytokinesis, we analyzed the roles of the myosin-II isoforms, Myo2 and Myp2, of the fission yeast Schizosaccharomyces pombe, in cytokinesis under normal and stressed conditions. We found that Myp2 controls the disassembly, stability, and constriction initiation of the Myo2 ring in response to high-salt stress. A C-terminal coiled-coil domain of Myp2 is required for its immobility and contractility during cytokinesis, and when fused to the tail of the dynamic Myo2, renders the chimera the low-turnover property. We also found, by following distinct processes in real time at the single-cell level, that Myo2 and Myp2 are differentially required but collectively essential for guiding extracellular matrix remodeling during cytokinesis. These results suggest that the dynamic and immobile myosin-II isoforms are evolved to carry out cytokinesis with robustness under different growth conditions. The myosin-II isoforms Myo2 and Myp2 display distinct responses to cellular stress Myp2 controls the constriction initiation of Myo2 during stress response A C-terminal region of Myp2 is required for its immobility during cytokinesis Myo2 and Myp2 are differentially required for guiding ECM remodeling during cytokinesis
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Affiliation(s)
- Hiroki Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA
| | - Carsten Wloka
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA; Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, 9747 AE Groningen, The Netherlands
| | - Jian-Qiu Wu
- Department of Molecular Genetics, The Ohio State University, Columbus, OH 43210, USA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104-6058, USA.
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36
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Perez AM, Thorner J. Septin-associated proteins Aim44 and Nis1 traffic between the bud neck and the nucleus in the yeast Saccharomyces cerevisiae. Cytoskeleton (Hoboken) 2019; 76:15-32. [PMID: 30341817 PMCID: PMC6474838 DOI: 10.1002/cm.21500] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 09/25/2018] [Accepted: 10/10/2018] [Indexed: 12/20/2022]
Abstract
In budding yeast, a collar of septin filaments at the neck between a mother cell and its bud marks the incipient site for cell division and serves as a scaffold that recruits proteins required for proper spatial and temporal execution of cytokinesis. A set of interacting proteins that localize at or near the bud neck, including Aim44/Gps1, Nba1 and Nis1, also has been implicated in preventing Cdc42-dependent bud site re-establishment at the division site. We found that, at their endogenous level, Aim44 and Nis1 robustly localize sequentially at the septin collar. Strikingly, however, when overproduced, both proteins shift their subcellular distribution predominantly to the nucleus. Aim44 localizes with the inner nuclear envelope, as well as at the plasma membrane, whereas Nis1 accumulates within the nucleus, indicating that these proteins normally undergo nucleocytoplasmic shuttling. Of the 14 yeast karyopherins, Kap123/Yrb4 is the primary importin for Aim44, whereas several importins mediate Nis1 nuclear entry. Conversely, Kap124/Xpo1/Crm1 is the primary exportin for Nis1, whereas both Xpo1 and Cse1/Kap109 likely contribute to Aim44 nuclear export. Even when endogenously expressed, Nis1 accumulates in the nucleus when Nba1 is absent. When either Aim44 or Nis1 are overexpressed, Nba1 is displaced from the bud neck, further consistent with the mutual interactions of these proteins. Collectively, our results indicate that a previously unappreciated level at which localization of septin-associated proteins is controlled is via regulation of their nucleocytoplasmic shuttling, which places constraints on their availability for complex formation with other partners at the bud neck.
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Affiliation(s)
- Adam M. Perez
- Division of Biochemistry, Biophysics and Structural BiologyDepartment of Molecular and Cell Biology, University of CaliforniaBerkeleyCalifornia
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural BiologyDepartment of Molecular and Cell Biology, University of CaliforniaBerkeleyCalifornia
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37
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Akhmetova KA, Chesnokov IN, Fedorova SA. [Functional Characterization of Septin Complexes]. Mol Biol (Mosk) 2018; 52:155-171. [PMID: 29695686 DOI: 10.7868/s0026898418020015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Accepted: 10/27/2016] [Indexed: 12/28/2022]
Abstract
Septins belong to a family of conserved GTP-binding proteins found in majority of eukaryotic species except for higher plants. Septins form nonpolar complexes that further polymerize into filaments and associate with cell membranes, thus comprising newly acknowledged cytoskeletal system. Septins participate in a variety of cell processes and contribute to various pathophysiological states, including tumorigenesis and neurodegeneration. Here, we review the structural and functional properties of septins and the regulation of their dynamics with special emphasis on the role of septin filaments as a cytoskeletal system and its interaction with actin and microtubule cytoskeletons. We also discuss how septins compartmentalize the cell by forming local protein-anchoring scaffolds and by providing barriers for the lateral diffusion of the membrane proteins.
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Affiliation(s)
- K A Akhmetova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,University of Alabama at Birmingham, Birmingham, 35294 USA.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia
| | - I N Chesnokov
- University of Alabama at Birmingham, Birmingham, 35294 USA
| | - S A Fedorova
- Institute of Cytology and Genetics, Siberian Branch of the Russian Academy of Sciences, Novosibirsk, 630090 Russia.,Novosibirsk National Research State University, Novosibirsk, 630090 Russia.,
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38
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Molecular mechanisms of contractile-ring constriction and membrane trafficking in cytokinesis. Biophys Rev 2018; 10:1649-1666. [PMID: 30448943 DOI: 10.1007/s12551-018-0479-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 11/06/2018] [Indexed: 12/14/2022] Open
Abstract
In this review, we discuss the molecular mechanisms of cytokinesis from plants to humans, with a focus on contribution of membrane trafficking to cytokinesis. Selection of the division site in fungi, metazoans, and plants is reviewed, as well as the assembly and constriction of a contractile ring in fungi and metazoans. We also provide an introduction to exocytosis and endocytosis, and discuss how they contribute to successful cytokinesis in eukaryotic cells. The conservation in the coordination of membrane deposition and cytoskeleton during cytokinesis in fungi, metazoans, and plants is highlighted.
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39
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Homoto S, Izawa S. Persistent actin depolarization caused by ethanol induces the formation of multiple small cortical septin rings in yeast. J Cell Sci 2018; 131:jcs.217091. [PMID: 29991513 DOI: 10.1242/jcs.217091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/03/2018] [Indexed: 11/20/2022] Open
Abstract
Short-term exposure to severe ethanol stress has adverse effects on yeast cells. However, limited information is available on the effects of long-term exposure to severe ethanol stress. In this study, we examined the effects of a long-term treatment with a high ethanol concentration [10% (v/v)] on yeast morphology. We found that long-term severe ethanol stress induced the continuous depolarization of the actin cytoskeleton and hypertrophy in yeast cells, accompanied by the aberrant localization of septins, which formed multiple small cortical rings (MSCRs). The formation of MSCRs was also induced by the continuous depolarization of the actin cytoskeleton caused by a treatment with latrunculin-A, an effective inhibitor of actin polymerization. Unlike the formation of conventional septin rings, the formation of MSCRs did not require Cdc42 and its effectors, Gic1, Gic2 and Cla4. These results provide novel insights into the effects of persistent actin depolarization caused by long-term exposure to severe ethanol stress on yeast cytomorphology.
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Affiliation(s)
- Sena Homoto
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
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40
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Marquardt J, Chen X, Bi E. Architecture, remodeling, and functions of the septin cytoskeleton. Cytoskeleton (Hoboken) 2018; 76:7-14. [PMID: 29979831 DOI: 10.1002/cm.21475] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 06/05/2018] [Accepted: 06/22/2018] [Indexed: 01/22/2023]
Abstract
The septin family of proteins has fascinated cell biologists for decades due to the elaborate architecture they adopt in different eukaryotic cells. Whether they exist as rings, collars, or gauzes in different cell types and at different times in the cell cycle illustrates a complex series of regulation in structure. While the organization of different septin structures at the cortex of different cell types during the cell cycle has been described to various degrees, the exact structure and regulation at the filament level are still largely unknown. Recent advances in fluorescent and electron microscopy, as well as work in septin biochemistry, have allowed new insights into the aspects of septin architecture, remodeling, and function in many cell types. This mini-review highlights many of the recent findings with an emphasis on the budding yeast model.
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Affiliation(s)
- Joseph Marquardt
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, Pennsylvania
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41
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Spang A. The endoplasmic reticulum-the caring mother of the cell. Curr Opin Cell Biol 2018; 53:92-96. [PMID: 30006039 DOI: 10.1016/j.ceb.2018.06.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 06/06/2018] [Accepted: 06/11/2018] [Indexed: 11/28/2022]
Abstract
In eukaryotic cells, various cellular functions are compartmentalized and performed by sophisticated and specialized organelles. However, the membrane-bounded organelles need to communicate with each other and with the cytoplasm, and sense the outside through the plasma membrane to coordinate various functions and to maintain cellular homeostasis. To maintain homeostasis, the information on the cellular state must be collected and appropriate responses initiated. The endoplasmic reticulum fulfils these functions. In this review, I will discuss various aspects of how the ER senses and relays information and acts to protect the cell, in what sometimes could be interpreted as an altruistic behavior.
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Affiliation(s)
- Anne Spang
- Biozentrum, University of Basel, Klingelbergstrasse 70, CH-4056 Basel, Switzerland
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42
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Zheng S, Dong F, Rasul F, Yao X, Jin QW, Zheng F, Fu C. Septins regulate the equatorial dynamics of the separation initiation network kinase Sid2p and glucan synthases to ensure proper cytokinesis. FEBS J 2018; 285:2468-2480. [PMID: 29722930 DOI: 10.1111/febs.14487] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 04/18/2018] [Accepted: 04/24/2018] [Indexed: 12/31/2022]
Abstract
Septins generally function as scaffolds and as cortical barriers to restrict the diffusion of membrane proteins. In the fission yeast Schizosaccharomyces pombe, septins form a ring structure at the septum after spindle breakdown during the constriction of the contractile actomyosin ring (CAR) and serve as a scaffold to recruit glucanases to mediate ultimate daughter cell separation. Despite this, it remains unclear if septins play any significant roles before the cell separation during cytokinesis. Employing live cell microscopy, we carefully examined SIN (Septation Initiation Network) signaling and glucan synthases, two key factors ensuring proper function of the CAR. In the absence of the core septin component Spn1p, the formation of a compact CAR is advanced and the CAR constriction rate is slightly but significantly decreased. Moreover, the SIN kinase Sid2p and the glucan synthases Bgs1p and Ags1p form an equatorial ring quite prematurely, but their maintenance at the equatorial region is diminished spn1Δ cells. These findings suggest that septins act as key players in an accurate establishment and the maintenance of CAR by orchestrating the equatorial dynamics of Sid2p and glucan synthases. Hence, this work demonstrates that, in addition to their function during ultimate cell septation, septins have important roles in regulating earlier cytokinetic events, including CAR assembly and constriction, SIN signaling, and the cortical dynamics of the glucan synthases.
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Affiliation(s)
- Shengnan Zheng
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Fenfen Dong
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Faiz Rasul
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Xuebiao Yao
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Quan-Wen Jin
- State Key Laboratory of Cellular Stress Biology, School of Life Sciences, Xiamen University, Fujian, China
| | - Fan Zheng
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
| | - Chuanhai Fu
- Chinese Academy of Sciences Center for Excellence in Molecular Cell Biology, School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, China.,Anhui Key Laboratory for Cellular Dynamics & Chemical Biology, University of Science and Technology of China, Hefei, Anhui, China
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Barve G, Sanyal P, Manjithaya R. Septin localization and function during autophagy. Curr Genet 2018; 64:1037-1041. [PMID: 29651536 DOI: 10.1007/s00294-018-0834-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 03/27/2018] [Accepted: 04/05/2018] [Indexed: 01/11/2023]
Abstract
Autophagy is a vital conserved recycling process where eukaryotic cells remove unwanted proteins and organelles via lysosomal degradation and in turn, generate nutrients for the cells. The special feature of autophagy process is the formation of double-membrane vesicles called autophagosomes that engulf cellular cargo and deliver them to the vacuole or lysosomes for degradation. Inspite of more than 40 AuTophaGy (ATG) proteins and several organelles as known membrane source, autophagosome biogenesis is not entirely understood. We recently have discovered that septins contribute to autophagosome biogenesis. Septins are GTP-binding proteins, usually localized at the bud neck region and are involved in cytokinesis. Here, we show that during autophagy prevalent conditions, septins traffic between different cellular compartments such as Golgi, mitochondria, endosomes, plasma membrane, and vacuolar membranes.
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Affiliation(s)
- Gaurav Barve
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India
| | - Priyadarshini Sanyal
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India
| | - Ravi Manjithaya
- Molecular Biology and Genetics Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India.
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45
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Nguyen LT, Swulius MT, Aich S, Mishra M, Jensen GJ. Coarse-grained simulations of actomyosin rings point to a nodeless model involving both unipolar and bipolar myosins. Mol Biol Cell 2018; 29:1318-1331. [PMID: 29851561 PMCID: PMC5994903 DOI: 10.1091/mbc.e17-12-0736] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Cytokinesis in many eukaryotic cells is orchestrated by a contractile actomyosin ring. While many of the proteins involved are known, the mechanism of constriction remains unclear. Informed by the existing literature and new three-dimensional (3D) molecular details from electron cryotomography, here we develop 3D coarse-grained models of actin filaments, unipolar and bipolar myosins, actin cross-linkers, and membranes and simulate their interactions. Assuming that local force on the membrane results in inward growth of the cell wall, we explored a matrix of possible actomyosin configurations and found that node-based architectures like those presently described for ring assembly result in membrane puckers not seen in electron microscope images of real cells. Instead, the model that best matches data from fluorescence microscopy, electron cryotomography, and biochemical experiments is one in which actin filaments transmit force to the membrane through evenly distributed, membrane-attached, unipolar myosins, with bipolar myosins in the ring driving contraction. While at this point this model is only favored (not proven), the work highlights the power of coarse-grained biophysical simulations to compare complex mechanistic hypotheses.
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Affiliation(s)
- Lam T Nguyen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Matthew T Swulius
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
| | - Samya Aich
- Tata Institute of Fundamental Research, Mumbai 400005, India
| | | | - Grant J Jensen
- California Institute of Technology, Pasadena, CA 91125.,Howard Hughes Medical Institute, Chevy Chase, MD 20815
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Foltman M, Filali-Mouncef Y, Crespo D, Sanchez-Diaz A. Cell polarity protein Spa2 coordinates Chs2 incorporation at the division site in budding yeast. PLoS Genet 2018; 14:e1007299. [PMID: 29601579 PMCID: PMC5895073 DOI: 10.1371/journal.pgen.1007299] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Revised: 04/11/2018] [Accepted: 03/07/2018] [Indexed: 01/06/2023] Open
Abstract
Deposition of additional plasma membrane and cargoes during cytokinesis in eukaryotic cells must be coordinated with actomyosin ring contraction, plasma membrane ingression and extracellular matrix remodelling. The process by which the secretory pathway promotes specific incorporation of key factors into the cytokinetic machinery is poorly understood. Here, we show that cell polarity protein Spa2 interacts with actomyosin ring components during cytokinesis. Spa2 directly binds to cytokinetic factors Cyk3 and Hof1. The lethal effects of deleting the SPA2 gene in the absence of either Cyk3 or Hof1 can be suppressed by expression of the hypermorphic allele of the essential chitin synthase II (Chs2), a transmembrane protein transported on secretory vesicles that makes the primary septum during cytokinesis. Spa2 also interacts directly with the chitin synthase Chs2. Interestingly, artificial incorporation of Chs2 into the cytokinetic machinery allows the localisation of Spa2 at the site of division. In addition, increased Spa2 protein levels promote Chs2 incorporation at the site of division and primary septum formation. Our data indicate that Spa2 is recruited to the cleavage site to co-operate with the secretory vesicle system and particular actomyosin ring components to promote the incorporation of Chs2 into the so-called 'ingression progression complexes' during cytokinesis in budding yeast.
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Affiliation(s)
- Magdalena Foltman
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Yasmina Filali-Mouncef
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Damaso Crespo
- Departamento de Anatomía y Biología Celular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
| | - Alberto Sanchez-Diaz
- Instituto de Biomedicina y Biotecnología de Cantabria, Universidad de Cantabria, CSIC, Santander, Spain
- Departamento de Biología Molecular, Facultad de Medicina, Universidad de Cantabria, Santander, Spain
- * E-mail:
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Orellana-Muñoz S, Dueñas-Santero E, Arnáiz-Pita Y, Del Rey F, Correa-Bordes J, Vázquez de Aldana CR. The anillin-related Int1 protein and the Sep7 septin collaborate to maintain cellular ploidy in Candida albicans. Sci Rep 2018; 8:2257. [PMID: 29396461 PMCID: PMC5797091 DOI: 10.1038/s41598-018-20249-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Accepted: 01/15/2018] [Indexed: 11/13/2022] Open
Abstract
Variation in cell ploidy is a common feature of Candida albicans clinical isolates that are resistant to the antifungal drug fluconazole. Here, we report that the anillin-related protein Int1 interacts with septins for coupling cytokinesis with nuclear segregation. Loss of Int1 results in a rapid disassembly of duplicated septin rings from the bud neck at the onset of actomyosin ring contraction. Strikingly, this has no major impact on cytokinesis and septum formation. However, Int1 genetically interacts with the Sep7 septin, maintaining the diffusion barrier at the bud neck and guarantying a faithful nuclear segregation. Indeed, int1ΔΔ sep7ΔΔ mutant cells, in contrast to int1ΔΔ cdc10ΔΔ, undergo a premature activation of mitotic exit prior to the alignment of the mitotic spindle with the division axis, producing large multinucleated cells. Some of these multinucleated cells arise from trimeras similar to those observed upon fluconazole exposure. Finally, the defects in nuclear segregation could be in part due to the inability to maintain the Lte1 mitotic exit activator at the cortex of the daughter cell. These results suggest that Int1 and Sep7 play a role in maintaining genome stability by acting as a diffusion barrier for Lte1.
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Affiliation(s)
- Sara Orellana-Muñoz
- Instituto de Biología Funcional y Genómica, IBFG-CSIC. Universidad de Salamanca, Salamanca, Spain
| | | | - Yolanda Arnáiz-Pita
- Instituto de Biología Funcional y Genómica, IBFG-CSIC. Universidad de Salamanca, Salamanca, Spain
| | - Francisco Del Rey
- Instituto de Biología Funcional y Genómica, IBFG-CSIC. Universidad de Salamanca, Salamanca, Spain
| | - Jaime Correa-Bordes
- Departamento de Ciencias Biomédicas, Universidad de Extremadura, Badajoz, Spain
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48
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MCC/Eisosomes Regulate Cell Wall Synthesis and Stress Responses in Fungi. J Fungi (Basel) 2017; 3:jof3040061. [PMID: 29371577 PMCID: PMC5753163 DOI: 10.3390/jof3040061] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 10/26/2017] [Accepted: 10/31/2017] [Indexed: 12/20/2022] Open
Abstract
The fungal plasma membrane is critical for cell wall synthesis and other important processes including nutrient uptake, secretion, endocytosis, morphogenesis, and response to stress. To coordinate these diverse functions, the plasma membrane is organized into specialized compartments that vary in size, stability, and composition. One recently identified domain known as the Membrane Compartment of Can1 (MCC)/eisosome is distinctive in that it corresponds to a furrow-like invagination in the plasma membrane. MCC/eisosomes have been shown to be formed by the Bin/Amphiphysin/Rvs (BAR) domain proteins Lsp1 and Pil1 in a range of fungi. MCC/eisosome domains influence multiple cellular functions; but a very pronounced defect in cell wall synthesis has been observed for mutants with defects in MCC/eisosomes in some yeast species. For example, Candida albicans MCC/eisosome mutants display abnormal spatial regulation of cell wall synthesis, including large invaginations and altered chemical composition of the walls. Recent studies indicate that MCC/eisosomes affect cell wall synthesis in part by regulating the levels of the key regulatory lipid phosphatidylinositol 4,5-bisphosphate (PI4,5P2) in the plasma membrane. One general way MCC/eisosomes function is by acting as protected islands in the plasma membrane, since these domains are very stable. They also act as scaffolds to recruit >20 proteins. Genetic studies aimed at defining the function of the MCC/eisosome proteins have identified important roles in resistance to stress, such as resistance to oxidative stress mediated by the flavodoxin-like proteins Pst1, Pst2, Pst3 and Ycp4. Thus, MCC/eisosomes play multiple roles in plasma membrane organization that protect fungal cells from the environment.
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49
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Melloy PG, Rose MD. Influence of the bud neck on nuclear envelope fission in Saccharomyces cerevisiae. Exp Cell Res 2017; 358:390-396. [PMID: 28711459 DOI: 10.1016/j.yexcr.2017.07.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2017] [Revised: 07/06/2017] [Accepted: 07/11/2017] [Indexed: 11/30/2022]
Abstract
Studies have shown that nuclear envelope fission (karyokinesis) in budding yeast depends on cytokinesis, but not distinguished whether this was a direct requirement, indirect, because of cell cycle arrest, or due to bud neck-localized proteins impacting both processes. To determine the requirements for karyokinesis, we examined mutants conditionally defective for bud emergence and/or nuclear migration. The common mutant phenotype was completion of the nuclear division cycle within the mother cell, but karyokinesis did not occur. In the cdc24 swe1 mutant, at the non-permissive temperature, multiple nuclei accumulated within the unbudded cell, with connected nuclear envelopes. Upon return to the permissive temperature, the cdc24 swe1 mutant initiated bud emergence, but only the nucleus spanning the neck underwent fission suggesting that the bud neck region is important for fission initiation. The neck may be critical for either mechanical reasons, as the contractile ring might facilitate fission, or for regulatory reasons, as the site of a protein network regulating nuclear envelope fission, mitotic exit, and cytokinesis. We also found that 77-85% of pairs of septin mutant nuclei completed nuclear envelope fission. In addition, 27% of myo1Δ mutant nuclei completed karyokinesis. These data suggested that fission is not dependent on mechanical contraction at the bud neck, but was instead controlled by regulatory proteins there.
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Affiliation(s)
- Patricia G Melloy
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States; Department of Biological and Allied Health Sciences, Fairleigh Dickinson University, Madison, NJ, United States.
| | - Mark D Rose
- Department of Molecular Biology, Princeton University, Princeton, NJ, United States
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50
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Masgrau A, Battola A, Sanmartin T, Pryszcz LP, Gabaldón T, Mendoza M. Distinct roles of the polarity factors Boi1 and Boi2 in the control of exocytosis and abscission in budding yeast. Mol Biol Cell 2017; 28:3082-3094. [PMID: 28904204 PMCID: PMC5662264 DOI: 10.1091/mbc.e17-06-0404] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/31/2017] [Accepted: 09/06/2017] [Indexed: 01/09/2023] Open
Abstract
The budding yeast cortical proteins Boi1 and Boi2 were previously implicated in polarized growth and in inhibition of cytokinesis as part of the NoCut abscission checkpoint. This report establishes an essential role of Boi1 and Boi2 in vesicle exocytosis during bud growth, whereas Boi2 (but not Boi1) is required for abscission inhibition. Boi1 and Boi2 (Boi1/2) are budding yeast plasma membrane proteins that function in polarized growth, and in cytokinesis inhibition in response to chromosome bridges via the NoCut abscission checkpoint. How Boi1/2 act in these two distinct processes is not understood. We demonstrate that Boi1/2 are required for a late step in the fusion of secretory vesicles with the plasma membrane of the growing bud. Cells lacking Boi1/2 accumulate secretory vesicles and are defective in bud growth. In contrast, Boi2 is specifically required for abscission inhibition in cells with chromatin bridges. The SH3 domain of Boi2, which is dispensable for bud growth and targets Boi2 to the site of abscission, is necessary and sufficient for abscission inhibition. Gain of function of the exocyst, a conserved protein complex involved in tethering of exocytic vesicles to the plasma membrane, rescued secretion and bud growth defects in boi mutant cells, and abrogated NoCut checkpoint function. Thus Boi2 functions redundantly with Boi1 to promote the fusion of secretory vesicles with the plasma membrane at sites of polarized growth, and acts as an abscission inhibitor during cytokinesis in response to chromatin bridges.
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Affiliation(s)
- Aina Masgrau
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Andrea Battola
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Trinidad Sanmartin
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Leszek P Pryszcz
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Toni Gabaldón
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain.,Universitat Pompeu Fabra, 08003 Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats, 08010 Barcelona, Spain
| | - Manuel Mendoza
- Centre for Genomic Regulation, The Barcelona Institute of Science and Technology, 08003 Barcelona, Spain .,Universitat Pompeu Fabra, 08003 Barcelona, Spain
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