1
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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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2
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Lanze CE, Konopka JB. Sur7 mediates a novel pathway for PI 4,5P 2 regulation in C. albicans that promotes stress resistance and cell wall morphogenesis. Mol Biol Cell 2024; 35:ar99. [PMID: 38776129 PMCID: PMC11244165 DOI: 10.1091/mbc.e23-08-0324] [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: 08/23/2023] [Revised: 05/01/2024] [Accepted: 05/15/2024] [Indexed: 06/11/2024] Open
Abstract
The human fungal pathogen Candida albicans can cause lethal systemic infections due to its ability to resist stress from the host and to undergo invasive hyphal growth. Previous studies showed that plasma membrane MCC/eisosome domains were important for virulence by promoting the ability of Sur7 to mediate normal cell wall morphogenesis and stress resistance. The sur7Δ mutant displayed abnormal clusters of PI4,5P2, suggesting that misregulation of this lipid underlies the sur7Δ phenotype. To test this, we increased PI4,5P2 levels by deleting combinations of the three PI4,5P2 5' phosphatase genes (INP51, INP52, and INP54) and found that some combinations, such as inp51Δ inp52Δ, gave phenotypes similar the sur7Δ mutant. In contrast, deleting one copy of MSS4, the gene that encodes the 5' kinase needed to create PI4,5P2, reduced the abnormal PI4,5P2 clusters and also decreased the abnormal cell wall and stress sensitive phenotypes of the sur7Δ mutant. Additional studies support a model that the abnormal PI4,5P2 patches recruit septin proteins, which in turn promote aberrant cell wall growth. These results identify Sur7 as a novel regulator of PI4,5P2 and highlight the critical role of PI4,5P2 in the regulation of C. albicans virulence properties.
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Affiliation(s)
- Carla E. Lanze
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222
| | - James B. Konopka
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794-5222
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3
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Neiman AM. Membrane and organelle rearrangement during ascospore formation in budding yeast. Microbiol Mol Biol Rev 2024:e0001324. [PMID: 38899894 DOI: 10.1128/mmbr.00013-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/21/2024] Open
Abstract
SUMMARYIn ascomycete fungi, sexual spores, termed ascospores, are formed after meiosis. Ascospore formation is an unusual cell division in which daughter cells are created within the cytoplasm of the mother cell by de novo generation of membranes that encapsulate each of the haploid chromosome sets created by meiosis. This review describes the molecular events underlying the creation, expansion, and closure of these membranes in the budding yeast, Saccharomyces cerevisiae. Recent advances in our understanding of the regulation of gene expression and the dynamic behavior of different membrane-bound organelles during this process are detailed. While less is known about ascospore formation in other systems, comparison to the distantly related fission yeast suggests that the molecular events will be broadly similar throughout the ascomycetes.
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Affiliation(s)
- Aaron M Neiman
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, New York, USA
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4
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Marquardt J, Chen X, Bi E. Reciprocal regulation by Elm1 and Gin4 controls septin hourglass assembly and remodeling. J Cell Biol 2024; 223:e202308143. [PMID: 38448162 PMCID: PMC10913813 DOI: 10.1083/jcb.202308143] [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: 08/29/2023] [Revised: 02/05/2024] [Accepted: 02/20/2024] [Indexed: 03/08/2024] Open
Abstract
The septin cytoskeleton is extensively regulated by posttranslational modifications, such as phosphorylation, to achieve the diversity of architectures including rings, hourglasses, and gauzes. While many of the phosphorylation events of septins have been extensively studied in the budding yeast Saccharomyces cerevisiae, the regulation of the kinases involved remains poorly understood. Here, we show that two septin-associated kinases, the LKB1/PAR-4-related kinase Elm1 and the Nim1/PAR-1-related kinase Gin4, regulate each other at two discrete points of the cell cycle. During bud emergence, Gin4 targets Elm1 to the bud neck via direct binding and phosphorylation to control septin hourglass assembly and stability. During mitosis, Elm1 maintains Gin4 localization via direct binding and phosphorylation to enable timely remodeling of the septin hourglass into a double ring. This mutual control between Gin4 and Elm1 ensures that septin architecture is assembled and remodeled in a temporally controlled manner to perform distinct functions during the cell cycle.
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Affiliation(s)
- Joseph Marquardt
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA
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5
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Tsai K, Zhou Z, Yang J, Xu Z, Xu S, Zandi R, Hao N, Chen W, Alber M. Study of Impacts of Two Types of Cellular Aging on the Yeast Bud Morphogenesis. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.29.582376. [PMID: 38464259 PMCID: PMC10925247 DOI: 10.1101/2024.02.29.582376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Understanding the mechanisms of cellular aging processes is crucial for attempting to extend organismal lifespan and for studying age-related degenerative diseases. Yeast cells divide through budding, providing a classical biological model for studying cellular aging. With their powerful genetics, relatively short lifespan and well-established signaling pathways also found in animals, yeast cells offer valuable insights into the aging process. Recent experiments suggested the existence of two aging modes in yeast characterized by nucleolar and mitochondrial declines, respectively. In this study, by analyzing experimental data it was shown that cells evolving into those two aging modes behave differently when they are young. While buds grow linearly in both modes, cells that consistently generate spherical buds throughout their lifespan demonstrate greater efficacy in controlling bud size and growth rate at young ages. A three-dimensional chemical-mechanical model was developed and used to suggest and test hypothesized mechanisms of bud morphogenesis during aging. Experimentally calibrated simulations showed that tubular bud shape in one aging mode could be generated by locally inserting new materials at the bud tip guided by the polarized Cdc42 signal during the early stage of budding. Furthermore, the aspect ratio of the tubular bud could be stabilized during the late stage, as observed in experiments, through a reduction on the new cell surface material insertion or an expansion of the polarization site. Thus model simulations suggest the maintenance of new cell surface material insertion or chemical signal polarization could be weakened due to cellular aging in yeast and other cell types.
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Affiliation(s)
- Kevin Tsai
- Department of Mathematics, University of California, Riverside, CA, United States of America
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
| | - Zhen Zhou
- Department of Molecular Biology, School of Biological Sciences, University of California, San Diego, CA, United States of America
| | - Jiadong Yang
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, United States of America
| | - Zhiliang Xu
- Applied and Computational Mathematics and Statistics Department, University of Notre Dame, Notre Dame, IN, United States of America
| | - Shixin Xu
- Duke Kunshan University, Kunshan, Jiangsu, China
| | - Roya Zandi
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
- Department of Physics and Astronomy, University of California, Riverside, CA, United States of America
- Biophysics Graduate Program, University of California, Riverside, CA, United States of America
| | - Nan Hao
- Department of Molecular Biology, School of Biological Sciences, University of California, San Diego, CA, United States of America
| | - Weitao Chen
- Department of Mathematics, University of California, Riverside, CA, United States of America
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
- Department of Molecular, Cell and Systems Biology, University of California, Riverside, CA, United States of America
- Biophysics Graduate Program, University of California, Riverside, CA, United States of America
| | - Mark Alber
- Department of Mathematics, University of California, Riverside, CA, United States of America
- Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
- Department of Bioengineering, University of California, Riverside, CA, United States of America
- Biophysics Graduate Program, University of California, Riverside, CA, United States of America
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6
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Zheng S, Zheng B, Fu C. The Roles of Septins in Regulating Fission Yeast Cytokinesis. J Fungi (Basel) 2024; 10:115. [PMID: 38392788 PMCID: PMC10890454 DOI: 10.3390/jof10020115] [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: 12/19/2023] [Revised: 01/26/2024] [Accepted: 01/28/2024] [Indexed: 02/24/2024] Open
Abstract
Cytokinesis is required to separate two daughter cells at the end of mitosis, and septins play crucial roles in many aspects of cytokinesis. While septins have been intensively studied in many model organisms, including the budding yeast Saccharomyces cerevisiae, septins have been relatively less characterized in the fission yeast Schizosaccharomyces pombe, which has proven to be an excellent model organism for studying fundamental cell biology. In this review, we summarize the findings of septins made in fission yeasts mainly from four aspects: the domain structure of septins, the localization of septins during the cell cycle, the roles of septins in regulating cytokinesis, and the regulatory proteins of septins.
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Affiliation(s)
- Shengnan Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Biyu Zheng
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
| | - Chuanhai Fu
- MOE Key Laboratory for Cellular Dynamics & Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei 230027, China
- Anhui Key Laboratory of Cellular Dynamics and Chemical Biology & Hefei National Research Center for Interdisciplinary Sciences at the Microscale, School of Life Sciences, University of Science and Technology of China, Hefei 230027, China
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7
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Zhovmer AS, Manning A, Smith C, Nguyen A, Prince O, Sáez PJ, Ma X, Tsygankov D, Cartagena-Rivera AX, Singh NA, Singh RK, Tabdanov ED. Septins provide microenvironment sensing and cortical actomyosin partitioning in motile amoeboid T lymphocytes. SCIENCE ADVANCES 2024; 10:eadi1788. [PMID: 38170778 DOI: 10.1126/sciadv.adi1788] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 12/01/2023] [Indexed: 01/05/2024]
Abstract
The all-terrain motility of lymphocytes in tissues and tissue-like gels is best described as amoeboid motility. For amoeboid motility, lymphocytes do not require specific biochemical or structural modifications to the surrounding extracellular matrix. Instead, they rely on changing shape and steric interactions with the microenvironment. However, the exact mechanism of amoeboid motility remains elusive. Here, we report that septins participate in amoeboid motility of T cells, enabling the formation of F-actin and α-actinin-rich cortical rings at the sites of cell cortex-indenting collisions with the extracellular matrix. Cortical rings compartmentalize cells into chains of spherical segments that are spatially conformed to the available lumens, forming transient "hourglass"-shaped steric locks onto the surrounding collagen fibers. The steric lock facilitates pressure-driven peristaltic propulsion of cytosolic content by individually contracting cell segments. Our results suggest that septins provide microenvironment-guided partitioning of actomyosin contractility and steric pivots required for amoeboid motility of T cells in tissue-like microenvironments.
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Affiliation(s)
- Alexander S Zhovmer
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Alexis Manning
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Chynna Smith
- Section on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Ashley Nguyen
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Olivia Prince
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Pablo J Sáez
- Cell Communication and Migration Laboratory, Institute of Biochemistry and Molecular Cell Biology, and Center for Experimental Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Xuefei Ma
- Center for Biologics Evaluation and Research, U.S. Food and Drug Administration, Silver Spring, MD, USA
| | - Denis Tsygankov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA, USA
| | - Alexander X Cartagena-Rivera
- Section on Mechanobiology, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bethesda, MD, USA
| | - Niloy A Singh
- Department of Hematology Oncology, University of Rochester Medical Center, Rochester, NY, USA
| | - Rakesh K Singh
- Department of Obstetrics and Gynecology, University of Rochester Medical Center, Rochester, NY, USA
| | - Erdem D Tabdanov
- Department of Pharmacology, Penn State College of Medicine, The Pennsylvania State University, Hershey-Hummelstown, PA, USA
- Penn State Cancer Institute, Penn State College of Medicine, The Pennsylvania State University, Hershey, PA, USA
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8
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Marquardt J, Chen X, Bi E. Elucidating the Synergistic Role of Elm1 and Gin4 Kinases in Regulating Septin Hourglass Assembly. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.08.566235. [PMID: 37986786 PMCID: PMC10659281 DOI: 10.1101/2023.11.08.566235] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The septin cytoskeleton is extensively regulated by post-translational modifications such as phosphorylation to achieve the diversity of architectures including rings, hourglass, and gauzes. While many of the phosphorylation events of septins have been extensively studied in the budding yeast Saccharomyces cerevisiae, the regulation of the kinases involved remains poorly understood. Here we show that two septin-associated kinases, the LKB1/PAR-4-related kinase Elm1 and the Nim1/PAR-1-related kinase Gin4, regulate each other at two discrete points of the cell cycle. During bud emergence, Gin4 targets Elm1 to the bud neck via direct binding and phosphorylation to control septin hourglass assembly and stability. During mitosis, Elm1 maintains Gin4 localization via direct binding and phosphorylation to enable timely remodeling of the septin hourglass into a double ring. This unique synergy ensures that septin architecture is assembled and remodeled in a temporally controlled manner to perform distinct functions during the cell cycle.
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Affiliation(s)
- Joseph Marquardt
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
- Current affiliation: Department of Biology, Western Kentucky University, Bowling Green, KY
| | - Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA
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9
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Marques da Silva R, Christe Dos Reis Saladino G, Antonio Leonardo D, D'Muniz Pereira H, Andréa Sculaccio S, Paula Ulian Araujo A, Charles Garratt R. A key piece of the puzzle: The central tetramer of the Saccharomyces cerevisiae septin protofilament and its implications for self-assembly. J Struct Biol 2023; 215:107983. [PMID: 37315820 DOI: 10.1016/j.jsb.2023.107983] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 06/02/2023] [Accepted: 06/10/2023] [Indexed: 06/16/2023]
Abstract
Septins, often described as the fourth component of the cytoskeleton, are structural proteins found in a vast variety of living beings. They are related to small GTPases and thus, generally, present GTPase activity which may play an important (although incompletely understood) role in their organization and function. Septins polymerize into long non-polar filaments, in which each subunit interacts with two others by alternating interfaces, NC and G. In Saccharomyces cerevisiae four septins are organized in the following manner, [Cdc11-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11]n in order to form filaments. Although septins were originally discovered in yeast and much is known regarding their biochemistry and function, only limited structural information about them is currently available. Here we present crystal structures of Cdc3/Cdc10 which provide the first view of the physiological interfaces formed by yeast septins. The G-interface has properties which place it in between that formed by SEPT2/SEPT6 and SEPT7/SEPT3 in human filaments. Switch I from Cdc10 contributes significantly to the interface, whereas in Cdc3 it is largely disorded. However, the significant negative charge density of the latter suggests it may have a unique role. At the NC-interface, we describe an elegant means by which the sidechain of a glutamine from helix α0 imitates a peptide group in order to retain hydrogen-bond continuity at the kink between helices α5 and α6 in the neighbouring subunit, thereby justifying the conservation of the helical distortion. Its absence from Cdc11, along with this structure's other unusual features are critically discussed by comparison with Cdc3 and Cdc10.
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Affiliation(s)
- Rafael Marques da Silva
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil
| | | | - Diego Antonio Leonardo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil
| | - Humberto D'Muniz Pereira
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil
| | - Susana Andréa Sculaccio
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil
| | - Ana Paula Ulian Araujo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil
| | - Richard Charles Garratt
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-723, Brazil.
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10
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Gabbert AM, Campanale JP, Mondo JA, Mitchell NP, Myers A, Streichan SJ, Miolane N, Montell DJ. Septins regulate border cell surface geometry, shape, and motility downstream of Rho in Drosophila. Dev Cell 2023; 58:1399-1413.e5. [PMID: 37329886 PMCID: PMC10519140 DOI: 10.1016/j.devcel.2023.05.017] [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: 09/18/2022] [Revised: 04/14/2023] [Accepted: 05/25/2023] [Indexed: 06/19/2023]
Abstract
Septins self-assemble into polymers that bind and deform membranes in vitro and regulate diverse cell behaviors in vivo. How their in vitro properties relate to their in vivo functions is under active investigation. Here, we uncover requirements for septins in detachment and motility of border cell clusters in the Drosophila ovary. Septins and myosin colocalize dynamically at the cluster periphery and share phenotypes but, surprisingly, do not impact each other. Instead, Rho independently regulates myosin activity and septin localization. Active Rho recruits septins to membranes, whereas inactive Rho sequesters septins in the cytoplasm. Mathematical analyses identify how manipulating septin expression levels alters cluster surface texture and shape. This study shows that the level of septin expression differentially regulates surface properties at different scales. This work suggests that downstream of Rho, septins tune surface deformability while myosin controls contractility, the combination of which governs cluster shape and movement.
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Affiliation(s)
- Allison M Gabbert
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Joseph P Campanale
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - James A Mondo
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Noah P Mitchell
- Kavli Institute for Theoretical Physics, University of California, Santa Barbara, Santa Barbara, CA 93106, USA; Physics Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Adele Myers
- Electrical and Computer Engineering Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Sebastian J Streichan
- Physics Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Nina Miolane
- Electrical and Computer Engineering Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Denise J Montell
- Molecular, Cellular and Developmental Biology Department, University of California, Santa Barbara, Santa Barbara, CA 93106, USA.
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11
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Werner B, Yadav S. Phosphoregulation of the septin cytoskeleton in neuronal development and disease. Cytoskeleton (Hoboken) 2023; 80:275-289. [PMID: 36127729 PMCID: PMC10025170 DOI: 10.1002/cm.21728] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2022] [Revised: 08/13/2022] [Accepted: 09/12/2022] [Indexed: 11/06/2022]
Abstract
Septins are highly conserved GTP-binding proteins that oligomerize and form higher order structures. The septin cytoskeleton plays an important role in cellular organization, intracellular transport, and cytokinesis. Kinase-mediated phosphorylation of septins regulates various aspects of their function, localization, and dynamics. Septins are enriched in the mammalian nervous system where they contribute to neurodevelopment and neuronal function. Emerging research has implicated aberrant changes in septin cytoskeleton in several human diseases. The mechanisms through which aberrant phosphorylation by kinases contributes to septin dysfunction in neurological disorders are poorly understood and represent an important question for future research with therapeutic implications. This review summarizes the current state of knowledge of the diversity of kinases that interact with and phosphorylate mammalian septins, delineates how phosphoregulation impacts septin dynamics, and describes how aberrant septin phosphorylation contributes to neurological disorders.
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Affiliation(s)
- Bailey Werner
- Department of Pharmacology, University of Washington, Seattle, WA, United States
| | - Smita Yadav
- Department of Pharmacology, University of Washington, Seattle, WA, United States
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12
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Nakamura M, Hui J, Parkhurst SM. Bending actin filaments: twists of fate. Fac Rev 2023; 12:7. [PMID: 37081903 PMCID: PMC10111394 DOI: 10.12703/r/12-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023] Open
Abstract
In many cellular contexts, intracellular actomyosin networks must generate directional forces to carry out cellular tasks such as migration and endocytosis, which play important roles during normal developmental processes. A number of different actin binding proteins have been identified that form linear or branched actin, and that regulate these filaments through activities such as bundling, crosslinking, and depolymerization to create a wide variety of functional actin assemblies. The helical nature of actin filaments allows them to better accommodate tensile stresses by untwisting, as well as to bend to great curvatures without breaking. Interestingly, this latter property, the bending of actin filaments, is emerging as an exciting new feature for determining dynamic actin configurations and functions. Indeed, recent studies using in vitro assays have found that proteins including IQGAP, Cofilin, Septins, Anillin, α-Actinin, Fascin, and Myosins-alone or in combination-can influence the bending or curvature of actin filaments. This bending increases the number and types of dynamic assemblies that can be generated, as well as the spectrum of their functions. Intriguingly, in some cases, actin bending creates directionality within a cell, resulting in a chiral cell shape. This actin-dependent cell chirality is highly conserved in vertebrates and invertebrates and is essential for cell migration and breaking L-R symmetry of tissues/organs. Here, we review how different types of actin binding protein can bend actin filaments, induce curved filament geometries, and how they impact on cellular functions.
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Affiliation(s)
- Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Justin Hui
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Susan M Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
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13
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Weems AD, Welf ES, Driscoll MK, Zhou FY, Mazloom-Farsibaf H, Chang BJ, Murali VS, Gihana GM, Weiss BG, Chi J, Rajendran D, Dean KM, Fiolka R, Danuser G. Blebs promote cell survival by assembling oncogenic signalling hubs. Nature 2023; 615:517-525. [PMID: 36859545 PMCID: PMC10881276 DOI: 10.1038/s41586-023-05758-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 01/25/2023] [Indexed: 03/03/2023]
Abstract
Most human cells require anchorage for survival. Cell-substrate adhesion activates diverse signalling pathways, without which cells undergo anoikis-a form of programmed cell death1. Acquisition of anoikis resistance is a pivotal step in cancer disease progression, as metastasizing cells often lose firm attachment to surrounding tissue2,3. In these poorly attached states, cells adopt rounded morphologies and form small hemispherical plasma membrane protrusions called blebs4-11. Bleb function has been thoroughly investigated in the context of amoeboid migration, but it has been examined far less in other scenarios12. Here we show by three-dimensional imaging and manipulation of cell morphological states that blebbing triggers the formation of plasma membrane-proximal signalling hubs that confer anoikis resistance. Specifically, in melanoma cells, blebbing generates plasma membrane contours that recruit curvature-sensing septin proteins as scaffolds for constitutively active mutant NRAS and effectors. These signalling hubs activate ERK and PI3K-well-established promoters of pro-survival pathways. Inhibition of blebs or septins has little effect on the survival of well-adhered cells, but in detached cells it causes NRAS mislocalization, reduced MAPK and PI3K activity, and ultimately, death. This unveils a morphological requirement for mutant NRAS to operate as an effective oncoprotein. Furthermore, whereas some BRAF-mutated melanoma cells do not rely on this survival pathway in a basal state, inhibition of BRAF and MEK strongly sensitizes them to both bleb and septin inhibition. Moreover, fibroblasts engineered to sustain blebbing acquire the same anoikis resistance as cancer cells even without harbouring oncogenic mutations. Thus, blebs are potent signalling organelles capable of integrating myriad cellular information flows into concerted cellular responses, in this case granting robust anoikis resistance.
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Affiliation(s)
- Andrew D Weems
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Erik S Welf
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
- Regeneron Pharmaceuticals, Tarrytown, NY, USA
| | - Meghan K Driscoll
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - Felix Y Zhou
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | | | - Bo-Jui Chang
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Vasanth S Murali
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Gabriel M Gihana
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Byron G Weiss
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Joseph Chi
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Divya Rajendran
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Kevin M Dean
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Reto Fiolka
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA.
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14
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Grupp B, Gronemeyer T. A biochemical view on the septins, a less known component of the cytoskeleton. Biol Chem 2023; 404:1-13. [PMID: 36423333 DOI: 10.1515/hsz-2022-0263] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/30/2022] [Indexed: 11/25/2022]
Abstract
The septins are a conserved family of guanine nucleotide binding proteins, often named the fourth component of the cytoskeleton. They self-assemble into non-polar filaments and further into higher ordered structures. Properly assembled septin structures are required for a wide range of indispensable intracellular processes such as cytokinesis, vesicular transport, polarity establishment and cellular adhesion. Septins belong structurally to the P-Loop NTPases. However, unlike the small GTPases like Ras, septins do not mediate signals to effectors through GTP binding and hydrolysis. The role of nucleotide binding and subsequent GTP hydrolysis by the septins is rather controversially debated. We compile here the structural features from the existing septin crystal- and cryo-EM structures regarding protofilament formation, inter-subunit interface architecture and nucleotide binding and hydrolysis. These findings are supplemented with a summary of available biochemical studies providing information regarding nucleotide binding and hydrolysis of fungal and mammalian septins.
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Affiliation(s)
- Benjamin Grupp
- Institute of Molecular Genetics and Cell Biology, Ulm University, James Franck Ring N27, 89081 Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Ulm University, James Franck Ring N27, 89081 Ulm, Germany
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15
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Park K, Leroux MR. Composition, organization and mechanisms of the transition zone, a gate for the cilium. EMBO Rep 2022; 23:e55420. [PMID: 36408840 PMCID: PMC9724682 DOI: 10.15252/embr.202255420] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Revised: 08/08/2022] [Accepted: 10/31/2022] [Indexed: 11/22/2022] Open
Abstract
The cilium evolved to provide the ancestral eukaryote with the ability to move and sense its environment. Acquiring these functions required the compartmentalization of a dynein-based motility apparatus and signaling proteins within a discrete subcellular organelle contiguous with the cytosol. Here, we explore the potential molecular mechanisms for how the proximal-most region of the cilium, termed transition zone (TZ), acts as a diffusion barrier for both membrane and soluble proteins and helps to ensure ciliary autonomy and homeostasis. These include a unique complement and spatial organization of proteins that span from the microtubule-based axoneme to the ciliary membrane; a protein picket fence; a specialized lipid microdomain; differential membrane curvature and thickness; and lastly, a size-selective molecular sieve. In addition, the TZ must be permissive for, and functionally integrates with, ciliary trafficking systems (including intraflagellar transport) that cross the barrier and make the ciliary compartment dynamic. The quest to understand the TZ continues and promises to not only illuminate essential aspects of human cell signaling, physiology, and development, but also to unravel how TZ dysfunction contributes to ciliopathies that affect multiple organ systems, including eyes, kidney, and brain.
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Affiliation(s)
- Kwangjin Park
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
- Present address:
Terry Fox LaboratoryBC CancerVancouverBCCanada
- Present address:
Department of Medical GeneticsUniversity of British ColumbiaVancouverBCCanada
| | - Michel R Leroux
- Department of Molecular Biology and BiochemistrySimon Fraser UniversityBurnabyBCCanada
- Centre for Cell Biology, Development, and DiseaseSimon Fraser UniversityBurnabyBCCanada
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16
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Gönczi M, Ráduly Z, Szabó L, Fodor J, Telek A, Dobrosi N, Balogh N, Szentesi P, Kis G, Antal M, Trencsenyi G, Dienes B, Csernoch L. Septin7 is indispensable for proper skeletal muscle architecture and function. eLife 2022; 11:e75863. [PMID: 35929607 PMCID: PMC9355566 DOI: 10.7554/elife.75863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 07/03/2022] [Indexed: 11/13/2022] Open
Abstract
Today septins are considered as the fourth component of the cytoskeleton, with the Septin7 isoform playing a critical role in the formation of higher-order structures. While its importance has already been confirmed in several intracellular processes of different organs, very little is known about its role in skeletal muscle. Here, using Septin7 conditional knockdown (KD) mouse model, the C2C12 cell line, and enzymatically isolated adult muscle fibers, the organization and localization of septin filaments are revealed, and an ontogenesis-dependent expression of Septin7 is demonstrated. KD mice displayed a characteristic hunchback phenotype with skeletal deformities, reduction in in vivo and in vitro force generation, and disorganized mitochondrial networks. Furthermore, knockout of Septin7 in C2C12 cells resulted in complete loss of cell division while KD cells provided evidence that Septin7 is essential for proper myotube differentiation. These and the transient increase in Septin7 expression following muscle injury suggest that it may be involved in muscle regeneration and development.
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Affiliation(s)
- Mónika Gönczi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Zsolt Ráduly
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - László Szabó
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Andrea Telek
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Nóra Dobrosi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Norbert Balogh
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - György Trencsenyi
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
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17
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Kim OV, Litvinov RI, Mordakhanova ER, Bi E, Vagin O, Weisel JW. Contribution of septins to human platelet structure and function. iScience 2022; 25:104654. [PMID: 35832887 PMCID: PMC9272382 DOI: 10.1016/j.isci.2022.104654] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2021] [Revised: 04/23/2022] [Accepted: 06/17/2022] [Indexed: 11/29/2022] Open
Abstract
Although septins have been well-studied in nucleated cells, their role in anucleate blood platelets remains obscure. Here, we elucidate the contribution of septins to human platelet structure and functionality. We show that Septin-2 and Septin-9 are predominantly distributed at the periphery of resting platelets and co-localize strongly with microtubules. Activation of platelets by thrombin causes clustering of septins and impairs their association with microtubules. Inhibition of septin dynamics with forchlorfenuron (FCF) reduces thrombin-induced densification of septins and lessens their colocalization with microtubules in resting and activated platelets. Exposure to FCF alters platelet shape, suggesting that septins stabilize platelet cytoskeleton. FCF suppresses platelet integrin αIIbβ3 activation, promotes phosphatidylserine exposure on activated platelets, and induces P-selectin expression on resting platelets, suggesting septin involvement in these processes. Inhibition of septin dynamics substantially reduces platelet contractility and abrogates their spreading on fibrinogen-coated surfaces. Overall, septins strongly contribute to platelet structure, activation and biomechanics.
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Affiliation(s)
- Oleg V. Kim
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Rustem I. Litvinov
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Elmira R. Mordakhanova
- Institute of Fundamental Medicine and Biology, Kazan Federal University, Kazan, Russian Federation
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
| | - Olga Vagin
- Department of Pediatrics, Geffen School of Medicine at UCLA, Los Angeles, CA, USA
- Veterans Affairs Greater Los Angeles Health Care System, Los Angeles, CA, USA
| | - John W. Weisel
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA
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18
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Galvin J, Curran E, Arteaga F, Goossens A, Aubuchon-Endsley N, McMurray MA, Moore J, Hansen KC, Chial HJ, Potter H, Brodsky JL, Coughlan CM. Proteasome activity modulates amyloid toxicity. FEMS Yeast Res 2022; 22:foac004. [PMID: 35150241 PMCID: PMC8906389 DOI: 10.1093/femsyr/foac004] [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: 10/11/2021] [Revised: 12/14/2021] [Accepted: 02/10/2022] [Indexed: 11/13/2022] Open
Abstract
Alzheimer's disease (AD) is responsible for 60%-80% of identified cases of dementia. While the generation and accumulation of amyloid precursor protein (APP) fragments is accepted as a key step in AD pathogenesis, the precise role of these fragments remains poorly understood. To overcome this deficit, we induced the expression of the soluble C-terminal fragment of APP (C99), the rate-limiting peptide for the generation of amyloid fragments, in yeast that contain thermosensitive mutations in genes encoding proteasome subunits. Our previous work with this system demonstrated that these proteasome-deficient yeast cells, expressing C99 when proteasome activity was blunted, generated amyloid fragments similar to those observed in AD patients. We now report the phenotypic repercussions of inducing C99 expression in proteasome-deficient cells. We show increased levels of protein aggregates, cellular stress and chaperone expression, electron-dense accumulations in the nuclear envelope/ER, abnormal DNA condensation, and an induction of apoptosis. Taken together, these findings suggest that the generation of C99 and its associated fragments in yeast cells with compromised proteasomal activity results in phenotypes that may be relevant to the neuropathological processes observed in AD patients. These data also suggest that this yeast model should be useful for testing therapeutics that target AD-associated amyloid, since it allows for the assessment of the reversal of the perturbed cellular physiology observed when degradation pathways are dysfunctional.
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Affiliation(s)
- John Galvin
- Department of Biological Sciences, University of Denver , Denver CO 80208, United States
| | - Elizabeth Curran
- Department of Biological Sciences, University of Denver , Denver CO 80208, United States
| | - Francisco Arteaga
- Department of Biological Sciences, University of Denver , Denver CO 80208, United States
| | - Alicia Goossens
- Department of Biological Sciences, University of Denver , Denver CO 80208, United States
| | - Nicki Aubuchon-Endsley
- Department of Biological Sciences, University of Denver , Denver CO 80208, United States
| | - Michael A McMurray
- Department of Cell and Developmental Biology, Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Jeffrey Moore
- Department of Cell and Developmental Biology, Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Kirk C Hansen
- Department of Biochemistry and Molecular Genetics, Anschutz Medical Campus, Aurora, CO 80045, United States
| | - Heidi J Chial
- University of Colorado Alzheimer's and Cognition Center (CUACC), Department of Neurology, School of Medicine, Anschutz Medical Campus, Aurora 80045, United States
| | - Huntington Potter
- University of Colorado Alzheimer's and Cognition Center (CUACC), Department of Neurology, School of Medicine, Anschutz Medical Campus, Aurora 80045, United States
| | - Jeffrey L Brodsky
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, United States
| | - Christina M Coughlan
- University of Colorado Alzheimer's and Cognition Center (CUACC), Department of Neurology, School of Medicine, Anschutz Medical Campus, Aurora 80045, United States
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19
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Rubio-Miranda JÁ, Cázares-Raga FE, Coy-Arechavaleta AS, Viettri M, Cortes-Martínez L, Lagunes-Guillén A, Chavez-Munguía B, Ludert JE, Hernández-Hernández FDLC. Septin 2 interacts with dengue virus replication complex proteins and participates in virus replication in mosquito cells. Virology 2022; 570:67-80. [DOI: 10.1016/j.virol.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/05/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022]
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20
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Marquardt J, Chen X, Bi E. Septin Assembly and Remodeling at the Cell Division Site During the Cell Cycle. Front Cell Dev Biol 2021; 9:793920. [PMID: 34901034 PMCID: PMC8656427 DOI: 10.3389/fcell.2021.793920] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
The septin family of proteins can assemble into filaments that further organize into different higher order structures to perform a variety of different functions in different cell types and organisms. In the budding yeast Saccharomyces cerevisiae, the septins localize to the presumptive bud site as a cortical ring prior to bud emergence, expand into an hourglass at the bud neck (cell division site) during bud growth, and finally “split” into a double ring sandwiching the cell division machinery during cytokinesis. While much work has been done to understand the functions and molecular makeups of these structures, the mechanisms underlying the transitions from one structure to another have largely remained elusive. Recent studies involving advanced imaging and in vitro reconstitution have begun to reveal the vast complexity involved in the regulation of these structural transitions, which defines the focus of discussion in this mini-review.
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Affiliation(s)
- Joseph Marquardt
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Xi Chen
- 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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21
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Huang J, Chen J, Liu F, He Q, Wu Y, Sun Q, Long M, Li T, Pan G, Zhou Z. Septin homologs cooperating in the Proliferative Stage of Microsporidia Nosema bombycis. J Invertebr Pathol 2021; 183:107600. [PMID: 33961882 DOI: 10.1016/j.jip.2021.107600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Revised: 04/21/2021] [Accepted: 04/26/2021] [Indexed: 10/21/2022]
Abstract
The single-celled pathogen Nosema bombycis, that can infect silkworm Bombyx mori and other lepidoptera including Spodoptera, is the first identified Microsporidia which has diplokaryotic nuclei throughout the life cycle. Septin proteins can form highly ordered filaments, bundles or ring structures related to the cytokinesis in fungi. Here, three septin proteins (NbSeptin1, NbSeptin2 and NbSeptin3) from Nosema bombycis CQ I are described. These proteins, appear to be conserved within the phylum Microsporidia. NbSeptins transcripts were detected throughout the pathogen developmental cycle and were significantly enhanced from second days of infection, which lead to our hypothesis that NbSeptins play a role in merogony. Immunofluorescence assay (IFA) revealed a broad distribution of NbSeptins in meronts and partly co-localization of NbSeptins. Interestingly, in some of meronts, NbSeptin2 and NbSeptin3 showed localization between the nuclei of the diplokaryon. Yeast two-hybrid and co-immunoprecipitation analysis verified that NbSeptins can interact with each other. Our findings suggest that NbSeptins can cooperate in the proliferation stage of Nosema bombycis and contribute towards the understanding of the rols of septins in microsporidia development.
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Affiliation(s)
- Jun Huang
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Jie Chen
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China.
| | - Fangyan Liu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Qiang He
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Yujiao Wu
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Quan Sun
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Mengxian Long
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Tian Li
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Guoqing Pan
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China
| | - Zeyang Zhou
- State Key Laboratory of Silkworm Genome Biology, Southwest University, Chongqing 400716, China; Chongqing Key Laboratory of Microsporidia Infection and Prevention, Chongqing 400716, China; Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural, Southwest University, Chongqing 400716, China; College of Life Science, Chongqing Normal University, Chongqing 400047, China.
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22
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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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23
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Morano AA, Dvorin JD. The Ringleaders: Understanding the Apicomplexan Basal Complex Through Comparison to Established Contractile Ring Systems. Front Cell Infect Microbiol 2021; 11:656976. [PMID: 33954122 PMCID: PMC8089483 DOI: 10.3389/fcimb.2021.656976] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/19/2021] [Indexed: 12/02/2022] Open
Abstract
The actomyosin contractile ring is a key feature of eukaryotic cytokinesis, conserved across many eukaryotic kingdoms. Recent research into the cell biology of the divergent eukaryotic clade Apicomplexa has revealed a contractile ring structure required for asexual division in the medically relevant genera Toxoplasma and Plasmodium; however, the structure of the contractile ring, known as the basal complex in these parasites, remains poorly characterized and in the absence of a myosin II homolog, it is unclear how the force required of a cytokinetic contractile ring is generated. Here, we review the literature on the basal complex in Apicomplexans, summarizing what is known about its formation and function, and attempt to provide possible answers to this question and suggest new avenues of study by comparing the Apicomplexan basal complex to well-studied, established cytokinetic contractile rings and their mechanisms in organisms such as S. cerevisiae and D. melanogaster. We also compare the basal complex to structures formed during mitochondrial and plastid division and cytokinetic mechanisms of organisms beyond the Opisthokonts, considering Apicomplexan diversity and divergence.
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Affiliation(s)
- Alexander A Morano
- Biological and Biomedical Sciences, Harvard Medical School, Boston, MA, United States.,Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States
| | - Jeffrey D Dvorin
- Division of Infectious Diseases, Boston Children's Hospital, Boston, MA, United States.,Department of Pediatrics, Harvard Medical School, Boston, MA, United States
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24
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Synergistic role of nucleotides and lipids for the self-assembly of Shs1 septin oligomers. Biochem J 2021; 477:2697-2714. [PMID: 32726433 DOI: 10.1042/bcj20200199] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 07/07/2020] [Accepted: 07/09/2020] [Indexed: 12/25/2022]
Abstract
Budding yeast septins are essential for cell division and polarity. Septins assemble as palindromic linear octameric complexes. The function and ultra-structural organization of septins are finely governed by their molecular polymorphism. In particular, in budding yeast, the end subunit can stand either as Shs1 or Cdc11. We have dissected, here, for the first time, the behavior of the Shs1 protomer bound to membranes at nanometer resolution, in complex with the other septins. Using electron microscopy, we have shown that on membranes, Shs1 protomers self-assemble into rings, bundles, filaments or two-dimensional gauzes. Using a set of specific mutants we have demonstrated a synergistic role of both nucleotides and lipids for the organization and oligomerization of budding yeast septins. Besides, cryo-electron tomography assays show that vesicles are deformed by the interaction between Shs1 oligomers and lipids. The Shs1-Shs1 interface is stabilized by the presence of phosphoinositides, allowing the visualization of micrometric long filaments formed by Shs1 protomers. In addition, molecular modeling experiments have revealed a potential molecular mechanism regarding the selectivity of septin subunits for phosphoinositide lipids.
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Magliozzi JO, Moseley JB. Connecting cell polarity signals to the cytokinetic machinery in yeast and metazoan cells. Cell Cycle 2021; 20:1-10. [PMID: 33397181 DOI: 10.1080/15384101.2020.1864941] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Polarized growth and cytokinesis are two fundamental cellular processes that exist in virtually all cell types. Mechanisms for asymmetric distribution of materials allow for cells to grow in a polarized manner. This gives rise to a variety of cell shapes seen throughout all cell types. Following polarized growth during interphase, dividing cells assemble a cytokinetic ring containing the protein machinery to constrict and separate daughter cells. Here, we discuss how cell polarity signaling pathways act on cytokinesis, with a focus on direct regulation of the contractile actomyosin ring (CAR). Recent studies have exploited phosphoproteomics to identify new connections between cell polarity kinases and CAR proteins. Existing evidence suggests that some polarity kinases guide the local organization of CAR proteins and structures while also contributing to global organization of the division plane within a cell. We provide several examples of this regulation from budding yeast, fission yeast, and metazoan cells. In some cases, kinase-substrate connections point to conserved processes in these different organisms. We point to several examples where future work can indicate the degree of conservation and divergence in the cell division process of these different organisms.
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Affiliation(s)
- Joseph O Magliozzi
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth , Hanover, New Hampshire, USA
| | - James B Moseley
- Department of Biochemistry and Cell Biology, The Geisel School of Medicine at Dartmouth , Hanover, New Hampshire, USA
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Kim J, Cooper JA. Junctional Localization of Septin 2 Is Required for Organization of Junctional Proteins in Static Endothelial Monolayers. Arterioscler Thromb Vasc Biol 2021; 41:346-359. [PMID: 33147991 PMCID: PMC7769918 DOI: 10.1161/atvbaha.120.315472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Septin 2 is localized at junctions in human microvascular endothelial monolayers. The junctional localization of septin 2 is necessary for organization of cell-cell adhesion proteins of endothelial cells. Approach and Results: Septin 2 was depleted at junctions by suppression of expression using shRNA, treatment with inflammatory cytokine, TNF (tumor necrosis factor)-α, and ectopic overexpression of septin 2 phosphatidylinositol 4,5-bisphosphate binding mutant defect in interaction with plasma membrane. Under those conditions, organizations and expression levels of various junctional proteins were analyzed. Confocal images of immunofluorescence staining showed substantial disorganization of adherens junctional proteins, nectin-2 and afadin, TJP (tight junction protein), ZO (zonula occludens)-1, and intercellular adhesion protein, PECAM-1 (platelet-endothelial cell adhesion molecule-1). Immunoblots for those proteins did not show significant changes in expression except for nectin-2 that highly increased in expression. Significant differential gene expression profiles and biological pathway analysis by septin 2 suppression and by TNF-α treatment using RNA-seq showed common overlapping pathways. The commonalities in expression may be consistent with the similar effects on the overall organization of cell-cell adhesion proteins. CONCLUSIONS Localization of septin 2 at cell junctions are required for the arrangement of junctional proteins and the integrity of the barrier formed by endothelial monolayers.
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Affiliation(s)
- Joanna Kim
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - John A. Cooper
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
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27
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Heasley LR, Singer E, Cooperman BJ, McMurray MA. Saccharomyces spores are born prepolarized to outgrow away from spore-spore connections and penetrate the ascus wall. Yeast 2020; 38:90-101. [PMID: 33238051 PMCID: PMC7898352 DOI: 10.1002/yea.3540] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/17/2020] [Accepted: 11/19/2020] [Indexed: 01/19/2023] Open
Abstract
How nonspore haploid Saccharomyces cells choose sites of budding and polarize towards pheromone signals in order to mate has been a subject of intense study. Unlike nonspore haploids, sibling spores produced via meiosis and sporulation by a diploid cell are physically interconnected and encased in a sac derived from the old cell wall of the diploid, called the ascus. Nonspore haploids bud adjacent to previous sites of budding, relying on stable cortical landmarks laid down during prior divisions, but because spore membranes are made de novo, it was assumed that, as is known for fission yeast, Saccharomyces spores break symmetry and polarize at random locations. Here, we show that this assumption is incorrect: Saccharomyces cerevisiae spores are born prepolarized to outgrow, prior to budding or mating, away from interspore bridges. Consequently, when spores bud within an intact ascus, their buds locally penetrate the ascus wall, and when they mate, the resulting zygotes adopt a unique morphology reflective of repolarization towards pheromone. Long-lived cortical foci containing the septin Cdc10 mark polarity sites, but the canonical bud site selection programme is dispensable for spore polarity, thus the origin and molecular composition of these landmarks remain unknown. These findings demand further investigation of previously overlooked mechanisms of polarity establishment and local cell wall digestion and highlight how a key step in the Saccharomyces life cycle has been historically neglected.
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Affiliation(s)
- Lydia R Heasley
- Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA.,Environmental Health and Radiological Sciences, Colorado State University, Fort Collins, Colorado, USA
| | - Emily Singer
- Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Benjamin J Cooperman
- Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael A McMurray
- Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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Woods BL, Gladfelter AS. The state of the septin cytoskeleton from assembly to function. Curr Opin Cell Biol 2020; 68:105-112. [PMID: 33188984 DOI: 10.1016/j.ceb.2020.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/01/2020] [Accepted: 10/08/2020] [Indexed: 01/09/2023]
Abstract
Septins are conserved guanine nucleotide-binding proteins that polymerize into filaments at the cell cortex or in association with other cytoskeletal proteins, such as actin or microtubules. As integral players in many morphogenic and signaling events, septins form scaffolds important for the recruitment of the cytokinetic machinery, organization of the plasma membrane, and orientation of cell polarity. Mutations in septins or their misregulation are associated with numerous diseases. Despite growing appreciation for the importance of septins in different aspects of cell biology and disease, septins remain relatively poorly understood compared with other cytoskeletal proteins. Here in this review, we highlight some of the recent developments of the last two years in the field of septin cell biology.
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Affiliation(s)
- Benjamin L Woods
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Amy S Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA; Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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Tsai K, Britton S, Nematbakhsh A, Zandi R, Chen W, Alber M. Role of combined cell membrane and wall mechanical properties regulated by polarity signals in cell budding. Phys Biol 2020; 17:065011. [PMID: 33085651 DOI: 10.1088/1478-3975/abb208] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Budding yeast, Saccharomyces cerevisiae, serves as a prime biological model to study mechanisms underlying asymmetric growth. Previous studies have shown that prior to bud emergence, polarization of a conserved small GTPase Cdc42 must be established on the cell membrane of a budding yeast. Additionally, such polarization contributes to the delivery of cell wall remodeling enzymes and hydrolase from cytosol through the membrane, to change the mechanical properties of the cell wall. This leads to the hypothesis that Cdc42 and its associated proteins at least indirectly regulate cell surface mechanical properties. However, how the surface mechanical properties in the emerging bud are changed and whether such change is important are not well understood. To test several hypothesised mechanisms, a novel three-dimensional coarse-grained particle-based model has been developed which describes inhomogeneous mechanical properties of the cell surface. Model simulations predict alternation of the levels of stretching and bending stiffness of the cell surface in the bud region by the polarized Cdc42 signals is essential for initiating bud formation. Model simulations also suggest that bud shape depends strongly on the distribution of the polarized signaling molecules while the neck width of the emerging bud is strongly impacted by the mechanical properties of the chitin and septin rings. Moreover, the temporal change of the bud mechanical properties is shown to affect the symmetry of the bud shape. The 3D model of asymmetric cell growth can also be used for studying viral budding and other vegetative reproduction processes performed via budding, as well as detailed studies of cell growth.
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Affiliation(s)
- Kevin Tsai
- Department of Mathematics, University of California, Riverside, CA, United States of America. Interdisciplinary Center for Quantitative Modeling in Biology, University of California, Riverside, CA, United States of America
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Jiao F, Cannon KS, Lin YC, Gladfelter AS, Scheuring S. The hierarchical assembly of septins revealed by high-speed AFM. Nat Commun 2020; 11:5062. [PMID: 33033254 PMCID: PMC7545167 DOI: 10.1038/s41467-020-18778-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 09/15/2020] [Indexed: 12/15/2022] Open
Abstract
Septins are GTP-binding proteins involved in diverse cellular processes including division and membrane remodeling. Septins form linear, palindromic heteromeric complexes that can assemble in filaments and higher-order structures. Structural studies revealed various septin architectures, but questions concerning assembly-dynamics and -pathways persist. Here we used high-speed atomic force microscopy (HS-AFM) and kinetic modeling which allowed us to determine that septin filament assembly was a diffusion-driven process, while formation of higher-order structures was complex and involved self-templating. Slightly acidic pH and increased monovalent ion concentrations favor filament-assembly, -alignment and -pairing. Filament-alignment and -pairing further favored diffusion-driven assembly. Pairing is mediated by the septin N-termini face, and may occur symmetrically or staggered, likely important for the formation of higher-order structures of different shapes. Multilayered structures are templated by the morphology of the underlying layers. The septin C-termini face, namely the C-terminal extension of Cdc12, may be involved in membrane binding.
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Affiliation(s)
- Fang Jiao
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Kevin S Cannon
- Department of Biology, University of North Carolina and Chapel Hill, Chapel Hill, NC, 27599, USA
| | - Yi-Chih Lin
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA
| | - Amy S Gladfelter
- Department of Biology, University of North Carolina and Chapel Hill, Chapel Hill, NC, 27599, USA
- Marine Biological Laboratory, Woods Hole, MA, 02543, USA
| | - Simon Scheuring
- Department of Anesthesiology, Weill Cornell Medicine, New York, NY, 10065, USA.
- Department of Physiology and Biophysics, Weill Cornell Medicine, New York, NY, 10065, USA.
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Discovery of broad-spectrum fungicides that block septin-dependent infection processes of pathogenic fungi. Nat Microbiol 2020; 5:1565-1575. [PMID: 32958858 DOI: 10.1038/s41564-020-00790-y] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Accepted: 08/24/2020] [Indexed: 11/09/2022]
Abstract
Many pathogenic fungi depend on the development of specialized infection structures called appressoria to invade their hosts and cause disease. Impairing the function of fungal infection structures therefore provides a potential means by which diseases could be prevented. In spite of this extraordinary potential, however, relatively few anti-penetrant drugs have been developed to control fungal diseases, of either plants or animals. In the present study, we report the identification of compounds that act specifically to prevent fungal infection. We found that the organization of septin GTPases, which are essential for appressorium-mediated infection in the rice blast fungus Magnaporthe oryzae, requires very-long-chain fatty acids (VLCFAs), which act as mediators of septin organization at membrane interfaces. VLCFAs promote septin recruitment to curved plasma membranes and depletion of VLCFAs prevents septin assembly and host penetration by M. oryzae. We observed that VLCFA biosynthesis inhibitors not only prevent rice blast disease, but also show effective, broad-spectrum fungicidal activity against a wide range of fungal pathogens of maize, wheat and locusts, without affecting their respective hosts. Our findings reveal a mechanism underlying septin-mediated infection structure formation in fungi and provide a class of fungicides to control diverse diseases of plants and animals.
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A First Step to a Biomarker of Curative Surgery in Colorectal Cancer by Liquid Biopsy of Methylated Septin 9 Gene. DISEASE MARKERS 2020; 2020:9761406. [PMID: 32566042 PMCID: PMC7293729 DOI: 10.1155/2020/9761406] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Accepted: 01/16/2020] [Indexed: 02/06/2023]
Abstract
Objectives To confirm that patients affected by colorectal cancer have the V2 region of Septin 9 (SEPT9) gene hypermethylated in the circulating free DNA from a peripheral blood sample before surgery and to determine if this hypermethylated DNA disappears from the patients after complete resection of the tumour. Methods Plasma from 10 patients with colorectal cancer was collected preoperative and three months after surgery. The analysis of the methylation status of the promoter region of the SEPT9 gene was performed using a 7500 Fast Real-Time PCR System. Results Hypermethylation of SEPT9 gene was detected in 8 out of 10 preoperative samples (one negative result was probed to be a Lynch syndrome) and in 4 out of 10 postoperative samples matching with the cases of recurrence or persistence of disease. This means that, in this sample, the preoperative sensitivity and specificity of the test were 88.9% and 100%, respectively, and there is 100% correlation between the positive results of the SEPT9 test and a recurrence/persistence of the disease in patients after surgical resection. Conclusions Our study shows that circulating hypermethylated SEPT9 is a specific colorectal cancer biomarker. This hypermethylated SEPT9 DNA disappears around three months after surgery and that circulating hypermethylated SEPT9 may be the first noninvasive marker for postsurgical diagnosis; this conclusion must be confirmed with a more significant number of patients.
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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: 14] [Impact Index Per Article: 3.5] [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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Johnson CR, Steingesser MG, Weems AD, Khan A, Gladfelter A, Bertin A, McMurray MA. Guanidine hydrochloride reactivates an ancient septin hetero-oligomer assembly pathway in budding yeast. eLife 2020; 9:e54355. [PMID: 31990274 PMCID: PMC7056273 DOI: 10.7554/elife.54355] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Accepted: 01/25/2020] [Indexed: 01/22/2023] Open
Abstract
Septin proteins evolved from ancestral GTPases and co-assemble into hetero-oligomers and cytoskeletal filaments. In Saccharomyces cerevisiae, five septins comprise two species of hetero-octamers, Cdc11/Shs1-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11/Shs1. Slow GTPase activity by Cdc12 directs the choice of incorporation of Cdc11 vs Shs1, but many septins, including Cdc3, lack GTPase activity. We serendipitously discovered that guanidine hydrochloride rescues septin function in cdc10 mutants by promoting assembly of non-native Cdc11/Shs1-Cdc12-Cdc3-Cdc3-Cdc12-Cdc11/Shs1 hexamers. We provide evidence that in S. cerevisiae Cdc3 guanidinium occupies the site of a 'missing' Arg side chain found in other fungal species where (i) the Cdc3 subunit is an active GTPase and (ii) Cdc10-less hexamers natively co-exist with octamers. We propose that guanidinium reactivates a latent septin assembly pathway that was suppressed during fungal evolution in order to restrict assembly to octamers. Since homodimerization by a GTPase-active human septin also creates hexamers that exclude Cdc10-like central subunits, our new mechanistic insights likely apply throughout phylogeny.
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Affiliation(s)
- Courtney R Johnson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Marc G Steingesser
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Andrew D Weems
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical CampusAuroraUnited States
| | - Anum Khan
- Department of Biology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Amy Gladfelter
- Department of Biology, University of North Carolina at Chapel HillChapel HillUnited States
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, CNRS UMR 168ParisFrance
- Sorbonne Université UPMC Univ Paris 06ParisFrance
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical CampusAuroraUnited States
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Hou J, Feng HQ, Chang HW, Liu Y, Li GH, Yang S, Sun CH, Zhang MZ, Yuan Y, Sun J, Zhu-Salzman K, Zhang H, Qin QM. The H3K4 demethylase Jar1 orchestrates ROS production and expression of pathogenesis-related genes to facilitate Botrytis cinerea virulence. THE NEW PHYTOLOGIST 2020; 225:930-947. [PMID: 31529514 DOI: 10.1111/nph.16200] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Histone 3 Lysine 4 (H3K4) demethylation is ubiquitous in organisms, however the roles of H3K4 demethylase JARID1(Jar1)/KDM5 in fungal development and pathogenesis remain largely unexplored. Here, we demonstrate that Jar1/KDM5 in Botrytis cinerea, the grey mould fungus, plays a crucial role in these processes. The BcJAR1 gene was deleted and its roles in fungal development and pathogenesis were investigated using approaches including genetics, molecular/cell biology, pathogenicity and transcriptomic profiling. BcJar1 regulates H3K4me3 and both H3K4me2 and H3K4me3 methylation levels during vegetative and pathogenic development, respectively. Loss of BcJAR1 impairs conidiation, appressorium formation and stress adaptation; abolishes infection cushion (IC) formation and virulence, but promotes sclerotium production in the ΔBcjar1 mutants. BcJar1 controls reactive oxygen species (ROS) production and proper assembly of Sep4, a core septin protein and virulence determinant, to initiate infection structure (IFS) formation and host penetration. Exogenous cAMP partially restored the mutant appressorium, but not IC, formation. BcJar1 orchestrates global expression of genes for ROS production, stress response, carbohydrate transmembrane transport, secondary metabolites, etc., which may be required for conidiation, IFS formation, host penetration and virulence of the pathogen. Our work systematically elucidates BcJar1 functions and provides novel insights into Jar1/KDM5-mediated H3K4 demethylation in regulating fungal development and pathogenesis.
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Affiliation(s)
- Jie Hou
- College of Plant Sciences, Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
- College of Forestry, BeiHua University, Jilin, 132013, China
| | - Hui-Qiang Feng
- College of Plant Sciences, Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
| | - Hao-Wu Chang
- Key Laboratory of Symbolic Computation and Knowledge Engineering, Ministry of Education, College of Computer Science and Technology, Jilin University, Changchun, 130012, China
| | - Yue Liu
- College of Plant Sciences, Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
| | - Gui-Hua Li
- College of Plant Sciences, Jilin University, Changchun, 130062, China
| | - Song Yang
- College of Plant Sciences, Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
| | - Chen-Hao Sun
- College of Plant Sciences, Jilin University, Changchun, 130062, China
| | - Ming-Zhe Zhang
- College of Plant Sciences, Jilin University, Changchun, 130062, China
| | - Ye Yuan
- College of Plant Sciences, Jilin University, Changchun, 130062, China
| | - Jiao Sun
- College of Plant Sciences, Jilin University, Changchun, 130062, China
| | - Keyan Zhu-Salzman
- Department of Entomology, Texas A&M University, College Station, TX, 77843, USA
| | - Hao Zhang
- Key Laboratory of Symbolic Computation and Knowledge Engineering, Ministry of Education, College of Computer Science and Technology, Jilin University, Changchun, 130012, China
| | - Qing-Ming Qin
- College of Plant Sciences, Key Laboratory of Zoonosis Research, Ministry of Education, Jilin University, Changchun, China
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Abstract
The metalloenzyme protein phosphatase 1 (PP1), which is responsible for ≥50% of all dephosphorylation reactions, is regulated by scores of regulatory proteins, including the highly conserved SDS22 protein. SDS22 has numerous diverse functions, surprisingly acting as both a PP1 inhibitor and as an activator. Here, we integrate cellular, biophysical, and crystallographic studies to address this conundrum. We discovered that SDS22 selectively binds a unique conformation of PP1 that contains a single metal (M2) at its active site, i.e., SDS22 traps metal-deficient inactive PP1. Furthermore, we showed that SDS22 dissociation is accompanied by a second metal (M1) being loaded into PP1, as free metal cannot dissociate the complex and M1-deficient mutants remain constitutively trapped by SDS22. Together, our findings reveal that M1 metal loading and loss are essential for PP1 regulation in cells, which has broad implications for PP1 maturation, activity, and holoenzyme subunit exchange.
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Transfer of the Septin Ring to Cytokinetic Remnants in ER Stress Directs Age-Sensitive Cell-Cycle Re-entry. Dev Cell 2019; 51:173-191.e5. [PMID: 31564614 DOI: 10.1016/j.devcel.2019.08.017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2018] [Revised: 05/19/2019] [Accepted: 08/23/2019] [Indexed: 02/06/2023]
Abstract
During cell division, the inheritance of a functional endoplasmic reticulum (ER) is ensured by the endoplasmic reticulum stress surveillance (ERSU) pathway. Activation of ERSU causes the septin ring to mislocalize, which blocks ER inheritance and cytokinesis. Here, we uncover that the septin ring in fact translocates to previously utilized cell division sites called cytokinetic remnants (CRMs). This unconventional translocation requires Nba1, a negative polarity regulator that normally prevents repolarization and re-budding at CRMs. Furthermore, septin ring translocation relies on the recruitment and activation of a key ERSU component Slt2 by Bem1, without activating Cdc42. Failure to transfer all septin subunits to CRMs delays the cell's ability to re-enter the cell cycle when ER homeostasis is restored and hinders cell growth after ER stress recovery. Thus, these deliberate but unprecedented rearrangements of cell polarity factors during ER stress safeguard cell survival and the timely cell-cycle re-entry upon ER stress recovery.
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Liu F, Chen J, Dang X, Meng X, Wang R, Bao J, Long M, Li T, Ma Q, Huang J, Pan G, Zhou Z. Nbseptin2 Expression Pattern and Its Interaction with Nb
PTP
1 during Microsporidia
Nosema bombycis
Polar Tube Extrusion. J Eukaryot Microbiol 2019; 67:45-53. [DOI: 10.1111/jeu.12752] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2019] [Revised: 06/19/2019] [Accepted: 07/10/2019] [Indexed: 01/16/2023]
Affiliation(s)
- Fangyan Liu
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Jie Chen
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Xiaoqun Dang
- Laboratory of Animal Biology Chongqing Normal University Chongqing 400047 China
| | - Xianzhi Meng
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Rong Wang
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Jialing Bao
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Mengxian Long
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Tian Li
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Qiang Ma
- Research Laboratory Center Chongqing Three Gorges Medical College Chongqing 404120 China
| | - Jun Huang
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Guoqing Pan
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
| | - Zeyang Zhou
- State Key Laboratory of Silkworm Genome Biology Southwest University Chongqing 400716 China
- Chongqing Key Laboratory of Microsporidia Infection and Control Southwest University Chongqing 400716 China
- Key Laboratory of Sericultural Biology and Genetic Breeding, Ministry of Agricultural Southwest University Chongqing 400716 China
- Laboratory of Animal Biology Chongqing Normal University Chongqing 400047 China
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Desterke C, Gassama-Diagne A. Protein-protein interaction analysis highlights the role of septins in membrane enclosed lumen and mRNA processing. Adv Biol Regul 2019; 73:100635. [PMID: 31420262 DOI: 10.1016/j.jbior.2019.100635] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2019] [Revised: 07/01/2019] [Accepted: 07/04/2019] [Indexed: 06/10/2023]
Abstract
Septins are a family of GTP-binding proteins that assemble into non-polar filaments which can be recruited to negatively charged membranes and serve as a scaffold to recruit cytosolic proteins and cytoskeletal elements such as microtubules and actin so that they can perform their important biological functions. Human septins consist of four groups, each with 13 members, and filaments formation usually involve members from each group in specific positions. However, little is known about the molecular mechanisms that drive the binding of septins to membranes and its importance to their biological functions. Here we have built a protein-protein interaction (PPI) network around human septins and highlighted the connections with 170 partners. Functional enrichment by inference of the network of septins and their partners revealed their participation in functions consistent with some of the roles described for septins, including cell cycle, cell division and cell shape, but we also identified septin partners in these functions that had not previously been described. Interestingly, we identified important and multiple connections between septins and mRNA processing and their export from the nucleus. Analysis of the enrichment of gene ontology cellular components highlighted some important interactions between molecules involved in the spliceosome with septin 2 and septin 7 in particular. RNA splicing regulates gene expression, and through it, cell fate, development and physiology. Mutations in components of the in the splicing machinery is linked to several diseases including cancer, thus taken together, the different analyses presented here open new perspectives to elucidate the pathobiological role of septins.
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Affiliation(s)
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif, F-94800, France; Université Paris-Sud, UMR-S 1193, Villejuif, F-94800, France.
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40
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Omrane M, Camara AS, Taveneau C, Benzoubir N, Tubiana T, Yu J, Guérois R, Samuel D, Goud B, Poüs C, Bressanelli S, Garratt RC, Thiam AR, Gassama-Diagne A. Septin 9 has Two Polybasic Domains Critical to Septin Filament Assembly and Golgi Integrity. iScience 2019; 13:138-153. [PMID: 30831549 PMCID: PMC6403118 DOI: 10.1016/j.isci.2019.02.015] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 10/12/2018] [Accepted: 02/13/2019] [Indexed: 12/11/2022] Open
Abstract
Septins are GTP-binding proteins involved in several membrane remodeling mechanisms. They associate with membranes, presumably using a polybasic domain (PB1) that interacts with phosphoinositides (PIs). Membrane-bound septins assemble into microscopic structures that regulate membrane shape. How septins interact with PIs and then assemble and shape membranes is poorly understood. Here, we found that septin 9 has a second polybasic domain (PB2) conserved in the human septin family. Similar to PB1, PB2 binds specifically to PIs, and both domains are critical for septin filament formation. However, septin 9 membrane association is not dependent on these PB domains, but on putative PB-adjacent amphipathic helices. The presence of PB domains guarantees protein enrichment in PI-contained membranes, which is critical for PI-enriched organelles. In particular, we found that septin 9 PB domains control the assembly and functionality of the Golgi apparatus. Our findings offer further insight into the role of septins in organelle morphology. Two polybasic domains mediate septin 9 interactions with PIs Human septins have amphipathic helices suitable for membrane binding Septin 9 polybasic domains mediate the formation of septin higher-order structures The mutation or depletion of septin polybasic domains induces Golgi fragmentation
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Affiliation(s)
- Mohyeddine Omrane
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France; Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France
| | - Amanda Souza Camara
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Cyntia Taveneau
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | - Nassima Benzoubir
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Thibault Tubiana
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | - Jinchao Yu
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, 91191 Gif-Sur- Yvette Cedex, France
| | - Raphaël Guérois
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France; Commissariat à l'Energie Atomique et aux Energies Alternatives, 91191 Gif-Sur- Yvette Cedex, France
| | - Didier Samuel
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Bruno Goud
- Institute Curie, PSL Research University, CNRS UMR 144, Paris, France
| | - Christian Poüs
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France
| | - Stéphane Bressanelli
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Université Paris-Sud, Université Paris-Saclay, 91198 Gif Sur Yvette Cedex, France
| | | | - Abdou Rachid Thiam
- Laboratoire de Physique de l'Ecole Normale Supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, Paris, France.
| | - Ama Gassama-Diagne
- INSERM, Unité 1193, Villejuif 94800, France; Université Paris-Sud, UMR-S 1193, Villejuif 94800, France.
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41
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Kubo K, Okada H, Shimamoto T, Kimori Y, Mizunuma M, Bi E, Ohnuki S, Ohya Y. Implications of maintenance of mother-bud neck size in diverse vital processes of Saccharomyces cerevisiae. Curr Genet 2019; 65:253-267. [PMID: 30066140 DOI: 10.1007/s00294-018-0872-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 07/17/2018] [Accepted: 07/25/2018] [Indexed: 11/25/2022]
Abstract
The mother-bud neck is defined as the boundary between the mother cell and bud in budding microorganisms, wherein sequential morphological events occur throughout the cell cycle. This study was designed to quantitatively investigate the morphology of the mother-bud neck in budding yeast Saccharomyces cerevisiae. Observation of yeast cells with time-lapse microscopy revealed an increase of mother-bud neck size through the cell cycle. After screening of yeast non-essential gene-deletion mutants with the image processing software CalMorph, we comprehensively identified 274 mutants with broader necks during S/G2 phase. Among these yeasts, we extensively analyzed 19 representative deletion mutants with defects in genes annotated to six gene ontology terms (polarisome, actin reorganization, endosomal tethering complex, carboxy-terminal domain protein kinase complex, DNA replication, and maintenance of DNA trinucleotide repeats). The representative broad-necked mutants exhibited calcofluor white sensitivity, suggesting defects in their cell walls. Correlation analysis indicated that maintenance of mother-bud neck size is important for cellular processes such as cell growth, system robustness, and replicative lifespan. We conclude that neck-size maintenance in budding yeast is regulated by numerous genes and has several aspects that are physiologically significant.
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Affiliation(s)
- Karen Kubo
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, 277-8562, Japan
| | - Hiroki Okada
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6058, USA
| | - Takuya Shimamoto
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, 277-8562, Japan
| | - Yoshitaka Kimori
- Department of Imaging Science, Center for Novel Science Initiatives, National Institutes of Natural Sciences, Okazaki, 444-8787, Japan
- Department of Management and Information Sciences, Faculty of Environmental and Information Sciences, Fukui University of Technology, Gakuen, Fukui City, Fukui, 910-8505, Japan
| | - Masaki Mizunuma
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima, 739-8530, Japan
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104-6058, USA
| | - Shinsuke Ohnuki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, 277-8562, Japan
| | - Yoshikazu Ohya
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, University of Tokyo, Kashiwa, Chiba, 277-8562, Japan.
- AIST-UTokyo Advanced Operando-Measurement Technology Open Innovation Laboratory (OPERANDO-OIL), National Institute of Advanced Industrial Science and Technology (AIST), Kashiwa, Chiba, 277-8565, Japan.
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42
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Auxier B, Dee J, Berbee ML, Momany M. Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs. BMC Evol Biol 2019; 19:4. [PMID: 30616529 PMCID: PMC6323724 DOI: 10.1186/s12862-018-1297-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 11/19/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Septins are cytoskeletal proteins important in cell division and in establishing and maintaining cell polarity. Although septins are found in various eukaryotes, septin genes had the richest history of duplication and diversification in the animals, fungi and protists that comprise opisthokonts. Opisthokont septin paralogs encode modular proteins that assemble into heteropolymeric higher order structures. The heteropolymers can create physical barriers to diffusion or serve as scaffolds organizing other morphogenetic proteins. How the paralogous septin modules interact to form heteropolymers is still unclear. Through comparative analyses, we hoped to clarify the evolutionary origin of septin diversity and to suggest which amino acid residues were responsible for subunit binding specificity. RESULTS Here we take advantage of newly sequenced genomes to reconcile septin gene trees with a species phylogeny from 22 animals, fungi and protists. Our phylogenetic analysis divided 120 septins representing the 22 taxa into seven clades (Groups) of paralogs. Suggesting that septin genes duplicated early in opisthokont evolution, animal and fungal lineages share septin Groups 1A, 4 and possibly also 1B and 2. Group 5 septins were present in fungi but not in animals and whether they were present in the opisthokont ancestor was unclear. Protein homology folding showed that previously identified conserved septin motifs were all located near interface regions between the adjacent septin monomers. We found specific interface residues associated with each septin Group that are candidates for providing subunit binding specificity. CONCLUSIONS This work reveals that duplication of septin genes began in an ancestral opisthokont more than a billion years ago and continued through the diversification of animals and fungi. Evidence for evolutionary conservation of ~ 49 interface residues will inform mutagenesis experiments and lead to improved understanding of the rules guiding septin heteropolymer formation and from there, to improved understanding of development of form in animals and fungi.
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Affiliation(s)
- Benjamin Auxier
- Department of Botany, University of British Columbia, Vancouver, Canada
- current address: Laboratory of Genetics, Wageningen University and Research, P.O. Box 16, 6700AA, Wageningen, The Netherlands
| | - Jaclyn Dee
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Mary L. Berbee
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, USA
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43
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Daniels CN, Zyla TR, Lew DJ. A role for Gic1 and Gic2 in Cdc42 polarization at elevated temperature. PLoS One 2018; 13:e0200863. [PMID: 30566437 PMCID: PMC6300207 DOI: 10.1371/journal.pone.0200863] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Accepted: 11/09/2018] [Indexed: 12/27/2022] Open
Abstract
The conserved Rho-family GTPase Cdc42 is a master regulator of polarity establishment in many cell types. Cdc42 becomes activated and concentrated in a region of the cell cortex, and recruits a variety of effector proteins to that site. In turn, many effectors participate in regulation of cytoskeletal elements in order to remodel the cytoskeleton in a polarized manner. The budding yeast Saccharomyces cerevisiae has served as a tractable model system for studies of cell polarity. In yeast cells, Cdc42 polarization involves a positive feedback loop in which effectors called p21-activated kinases (PAKs) act to recruit a Cdc42-directed guanine nucleotide exchange factor (GEF), generating more GTP-Cdc42 in areas that already have GTP-Cdc42. The GTPase-interacting components (GICs) Gic1 and Gic2 are also Cdc42 effectors, and have been implicated in regulation of the actin and septin cytoskeleton. However, we report that cells lacking GICs are primarily defective in polarizing Cdc42 itself, suggesting that they act upstream as well as downstream of Cdc42 in yeast. Our findings suggest that feedback pathways involving GTPase effectors may be more prevalent than had been appreciated.
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Affiliation(s)
- Christine N. Daniels
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Trevin R. Zyla
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
| | - Daniel J. Lew
- Department of Pharmacology and Cancer Biology, Duke University, Durham, North Carolina, United States of America
- * E-mail:
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44
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Mela A, Momany M. Septin mutations and phenotypes in S. cerevisiae. Cytoskeleton (Hoboken) 2018; 76:33-44. [PMID: 30171672 DOI: 10.1002/cm.21492] [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: 07/02/2018] [Revised: 08/09/2018] [Accepted: 08/22/2018] [Indexed: 11/07/2022]
Abstract
Septins are highly conserved guanosine triphosphate (GTP)-binding proteins that are a component of the cytoskeletal systems of virtually all eukaryotes (except higher plants). Septins play important roles in a multitude of cellular processes, including cytokinesis, establishment of cell polarity, and cellular partitioning. The ease of genetic screens and a fully sequenced genome have made Saccharomyces cerevisiae one of the most extensively studied and well-annotated model organisms in eukaryotic biology. Here, we present a synopsis of the known point mutations in the seven S. cerevisiae septin genes: CDC3, CDC10, CDC11, CDC12, SHS1, SPR3, and SPR28. We map these mutations onto septin protein structures, highlighting important conserved motifs, and relating the functional consequences of mutations in each domain.
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Affiliation(s)
- Alexander Mela
- Department of Plant Biology, University of Georgia, Athens, GA 30602
| | - Michelle Momany
- Department of Plant Biology, University of Georgia, Athens, GA 30602
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45
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Tamborrini D, Juanes MA, Ibanes S, Rancati G, Piatti S. Recruitment of the mitotic exit network to yeast centrosomes couples septin displacement to actomyosin constriction. Nat Commun 2018; 9:4308. [PMID: 30333493 PMCID: PMC6193047 DOI: 10.1038/s41467-018-06767-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2017] [Accepted: 09/10/2018] [Indexed: 01/11/2023] Open
Abstract
In many eukaryotic organisms cytokinesis is driven by a contractile actomyosin ring (CAR) that guides membrane invagination. What triggers CAR constriction at a precise time of the cell cycle is a fundamental question. In budding yeast CAR is assembled via a septin scaffold at the division site. A Hippo-like kinase cascade, the Mitotic Exit Network (MEN), promotes mitotic exit and cytokinesis, but whether and how these two processes are independently controlled by MEN is poorly understood. Here we show that a critical function of MEN is to promote displacement of the septin ring from the division site, which in turn is essential for CAR constriction. This is independent of MEN control over mitotic exit and involves recruitment of MEN components to the spindle pole body (SPB). Ubiquitination of the SPB scaffold Nud1 inhibits MEN signaling at the end of mitosis and prevents septin ring splitting, thus silencing the cytokinetic machinery. The Mitotic Exit Network (MEN) promotes mitotic exit and cytokinesis but if and how MEN independently controls these two processes is unclear. Here, the authors report that MEN displaces septins from the cell division site to promote actomyosin ring constriction, independently of MEN control of mitotic exit.
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Affiliation(s)
- Davide Tamborrini
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.,Max-Planck-Institute of Molecular Physiology, Otto-Hahn Str. 11, 44227, Dortmund, Germany
| | - Maria Angeles Juanes
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.,Brandeis University, 415 South Street, Waltham, MA, 02454, USA
| | - Sandy Ibanes
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France
| | - Giulia Rancati
- Institute of Medical Biology, 8a Biomedical Grove, Singapore, 138648, Singapore
| | - Simonetta Piatti
- Centre de Recherche en Biologie Cellulaire de Montpellier (CRBM), 1919 Route de Mende, 34293, Montpellier, France.
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46
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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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47
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Lai H, Chiou JG, Zhurikhina A, Zyla TR, Tsygankov D, Lew DJ. Temporal regulation of morphogenetic events in Saccharomyces cerevisiae. Mol Biol Cell 2018; 29:2069-2083. [PMID: 29927361 PMCID: PMC6232962 DOI: 10.1091/mbc.e18-03-0188] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023] Open
Abstract
Tip growth in fungi involves highly polarized secretion and modification of the cell wall at the growing tip. The genetic requirements for initiating polarized growth are perhaps best understood for the model budding yeast Saccharomyces cerevisiae. Once the cell is committed to enter the cell cycle by activation of G1 cyclin/cyclin-dependent kinase (CDK) complexes, the polarity regulator Cdc42 becomes concentrated at the presumptive bud site, actin cables are oriented toward that site, and septin filaments assemble into a ring around the polarity site. Several minutes later, the bud emerges. Here, we investigated the mechanisms that regulate the timing of these events at the single-cell level. Septin recruitment was delayed relative to polarity establishment, and our findings suggest that a CDK-dependent septin “priming” facilitates septin recruitment by Cdc42. Bud emergence was delayed relative to the initiation of polarized secretion, and our findings suggest that the delay reflects the time needed to weaken the cell wall sufficiently for the cell to bud. Rho1 activation by Rom2 occurred at around the time of bud emergence, perhaps in response to local cell-wall weakening. This report reveals regulatory mechanisms underlying the morphogenetic events in the budding yeast.
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Affiliation(s)
- Helen Lai
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710.,Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710
| | - Jian-Geng Chiou
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710
| | - Anastasia Zhurikhina
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332
| | - Trevin R Zyla
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710
| | - Denis Tsygankov
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University School of Medicine, Atlanta, GA 30332
| | - Daniel J Lew
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC 27710.,Department of Molecular Genetics and Microbiology, Duke University, Durham, NC 27710
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48
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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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49
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Wang X, Fei F, Qu J, Li C, Li Y, Zhang S. The role of septin 7 in physiology and pathological disease: A systematic review of current status. J Cell Mol Med 2018; 22:3298-3307. [PMID: 29602250 PMCID: PMC6010854 DOI: 10.1111/jcmm.13623] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Accepted: 03/05/2018] [Indexed: 12/22/2022] Open
Abstract
Septins are a conserved family of cytoskeletal GTPases present in different organisms, including yeast, drosophila, Caenorhabditis elegans and humans. In humans, septins are involved in various cellular processes, including exocytosis, apoptosis, leukemogenesis, carcinogenesis and neurodegeneration. Septin 7 is unique out of 13 human septins. Mammalian septin 6, septin 7, septin 2 and septin 9 coisolate together in complexes to form the core unit for the generation of the septin filaments. Physiological septin filaments are hetero‐oligomeric complexes consisting of core septin hexamers and octamers. Furthermore, septin 7 plays a crucial role in cytokinesis and mitosis. Septin 7 is localized to the filopodia and branches of developing hippocampal neurons, and is the most abundant septin in the adult rat forebrain as well as a structural component of the human and mouse sperm annuli. Septin 7 is crucial to the spine morphogenesis and dendrite growth in neurons, and is also a structural constituent of the annulus in human and mouse sperm. It can suppress growth of some tumours such as glioma and papillary thyroid carcinoma. However, the molecular mechanisms of involvement of septin 7 in human disease, especially in the development of cancer, remain unclear. This review focuses on the structure, function and mechanism of septin 7 in vivo, and summarizes the role of septin 7 in cell proliferation, cytokinesis, nervous and reproductive systems, as well as the underlying molecular events linking septin 7 to various diseases, such as Alzheimer's disease, schizophrenia, neuropsychiatric systemic lupus erythematosus, tumour and so on.
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Affiliation(s)
- Xinlu Wang
- Graduate School, Tianjin University of Traditional Chinese Medicine, Tianjin, China.,Department of Pathology, Tianjin Union Medical Center, Tianjin, China
| | - Fei Fei
- Department of Pathology, Tianjin Union Medical Center, Tianjin, China.,Nankai University School of Medicine, Nankai University, Tianjin, China
| | - Jie Qu
- Department of Pathology, Tianjin Union Medical Center, Tianjin, China.,Nankai University School of Medicine, Nankai University, Tianjin, China
| | - Chunyuan Li
- Department of Pathology, Tianjin Union Medical Center, Tianjin, China.,Nankai University School of Medicine, Nankai University, Tianjin, China
| | - Yuwei Li
- Department of Colorectal Surgery, Tianjin Union Medical Center, Tianjin, China
| | - Shiwu Zhang
- Department of Pathology, Tianjin Union Medical Center, Tianjin, China
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Wang M, Nishihama R, Onishi M, Pringle JR. Role of the Hof1-Cyk3 interaction in cleavage-furrow ingression and primary-septum formation during yeast cytokinesis. Mol Biol Cell 2018; 29:597-609. [PMID: 29321253 PMCID: PMC6004579 DOI: 10.1091/mbc.e17-04-0227] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 12/26/2017] [Accepted: 01/03/2018] [Indexed: 11/11/2022] Open
Abstract
In Saccharomyces cerevisiae, it is well established that Hof1, Cyk3, and Inn1 contribute to septum formation and cytokinesis. Because hof1∆ and cyk3∆ single mutants have relatively mild defects but hof1∆ cyk3∆ double mutants are nearly dead, it has been hypothesized that these proteins contribute to parallel pathways. However, there is also evidence that they interact physically. In this study, we examined this interaction and its functional significance in detail. Our data indicate that the interaction 1) is mediated by a direct binding of the Hof1 SH3 domain to a proline-rich motif in Cyk3; 2) occurs specifically at the time of cytokinesis but is independent of the (hyper)phosphorylation of both proteins that occurs at about the same time; 3) is dispensable for the normal localization of both proteins; 4) is essential for normal primary-septum formation and a normal rate of cleavage-furrow ingression; and 5) becomes critical for growth when either Inn1 or the type II myosin Myo1 (a key component of the contractile actomyosin ring) is absent. The similarity in phenotype between cyk3∆ mutants and mutants specifically lacking the Hof1-Cyk3 interaction suggests that the interaction is particularly important for Cyk3 function, but it may be important for Hof1 function as well.
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Affiliation(s)
- Meng Wang
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Ryuichi Nishihama
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - Masayuki Onishi
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
| | - John R Pringle
- Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305
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