1
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Stjepić V, Nakamura M, Hui J, Parkhurst SM. Two Septin complexes mediate actin dynamics during cell wound repair. Cell Rep 2024; 43:114215. [PMID: 38728140 PMCID: PMC11203717 DOI: 10.1016/j.celrep.2024.114215] [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: 11/16/2023] [Revised: 03/18/2024] [Accepted: 04/24/2024] [Indexed: 05/12/2024] Open
Abstract
Cells have robust wound repair systems to prevent further damage or infection and to quickly restore cell cortex integrity when exposed to mechanical and chemical stress. Actomyosin ring formation and contraction at the wound edge are major events during closure of the plasma membrane and underlying cytoskeleton during cell wound repair. Here, we show that all five Drosophila Septins are required for efficient cell wound repair. Based on their different recruitment patterns and knockdown/mutant phenotypes, two distinct Septin complexes, Sep1/Sep2/Pnut and Sep4/Sep5/Pnut, are assembled to regulate actin ring assembly, contraction, and remodeling during the repair process. Intriguingly, we find that these two Septin complexes have different F-actin bending activities. In addition, we find that Anillin regulates the recruitment of only one of two Septin complexes upon wounding. Our results demonstrate that two functionally distinct Septin complexes work side by side to discretely regulate actomyosin ring dynamics during cell wound repair.
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Affiliation(s)
- Viktor Stjepić
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Justin Hui
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA
| | - Susan M Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA 98109, USA.
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2
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Sharma K, Menon MB. Decoding post-translational modifications of mammalian septins. Cytoskeleton (Hoboken) 2023; 80:169-181. [PMID: 36797225 DOI: 10.1002/cm.21747] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/21/2023] [Accepted: 02/10/2023] [Indexed: 02/18/2023]
Abstract
Septins are cytoskeletal GTPases that form nonpolar filaments and higher-ordered structures and they take part in a wide range of cellular processes. Septins are conserved from yeast to mammals but absent from higher plants. The number of septin genes vary between organisms and they usually form complex heteropolymeric networks. Most septins are known to be capable of GTP hydrolysis which may regulate septin dynamics. Knowledge on regulation of septin function by post-translational modifications is still in its infancy. In this review article, we highlight the post-translational modifications reported for the 13 human septins and discuss their implications on septin functions. In addition to the functionally investigated modifications, we also try to make sense of the complex septin post-translational modification code revealed from large-scale phospho-proteomic datasets. Future studies may determine how these isoform-specific and homology group specific modifications affect septin structure and function.
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Affiliation(s)
- Khushboo Sharma
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Manoj B Menon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
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3
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Martens AK, Erwig M, Patzig J, Fledrich R, Füchtbauer EM, Werner HB. Targeted inactivation of the Septin2 and Septin9 genes in myelinating Schwann cells of mice. Cytoskeleton (Hoboken) 2023; 80:290-302. [PMID: 36378242 DOI: 10.1002/cm.21736] [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: 09/08/2022] [Revised: 11/03/2022] [Accepted: 11/11/2022] [Indexed: 11/16/2022]
Abstract
The formation of axon-enwrapping myelin sheaths by oligodendrocytes in the central nervous system involves the assembly of a scaffolding septin filament comprised of the subunits SEPTIN2, SEPTIN4, SEPTIN7 and SEPTIN8. Conversely, in the peripheral nervous system (PNS), myelin is synthesized by a different cell type termed Schwann cells, and it remained unknown if septins also assemble as a multimer in PNS myelin. According to prior proteome analysis, PNS myelin comprises the subunits SEPTIN2, SEPTIN7, SEPTIN8, SEPTIN9, and SEPTIN11, which localize to the paranodal and abaxonal myelin subcompartments. Here, we use the Cre/loxP-system to delete the Septin9-gene specifically in Schwann cells, causing a markedly reduced abundance of SEPTIN9 in sciatic nerves, implying that Schwann cells are the main cell type expressing SEPTIN9 in the nerve. However, Septin9-deficiency in Schwann cells did not affect the abundance or localization of other septin subunits. In contrast, when deleting the Septin2-gene in Schwann cells the abundance of all relevant septin subunits was markedly reduced, including SEPTIN9. Notably, we did not find evidence that deleting Septin2 or Septin9 in Schwann cells impairs myelin biogenesis, nerve conduction velocity or motor/sensory capabilities, at least at the assessed timepoints. Our data thus show that SEPTIN2 but not SEPTIN9 is required for the formation or stabilization of a septin multimer in PNS myelin in vivo; however, its functional relevance remains to be established.
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Affiliation(s)
- Ann-Kristin Martens
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Michelle Erwig
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Julia Patzig
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Robert Fledrich
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | | | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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4
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Cannon KS, Vargas-Muniz JM, Billington N, Seim I, Ekena J, Sellers JR, Gladfelter AS. A gene duplication of a septin reveals a developmentally regulated filament length control mechanism. J Cell Biol 2023; 222:e202204063. [PMID: 36786832 PMCID: PMC9960279 DOI: 10.1083/jcb.202204063] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 11/20/2022] [Accepted: 01/19/2023] [Indexed: 02/15/2023] Open
Abstract
Septins are a family of conserved filament-forming proteins that function in multiple cellular processes. The number of septin genes within an organism varies, and higher eukaryotes express many septin isoforms due to alternative splicing. It is unclear if different combinations of septin proteins in complex alter the polymers' biophysical properties. We report that a duplication event within the CDC11 locus in Ashbya gossypii gave rise to two similar but distinct Cdc11 proteins: Cdc11a and Cdc1b. CDC11b transcription is developmentally regulated, producing different amounts of Cdc11a- and Cdc11b-complexes in the lifecycle of Ashbya gossypii. Deletion of either gene results in distinct cell polarity defects, suggesting non-overlapping functions. Cdc11a and Cdc11b complexes have differences in filament length and membrane-binding ability. Thus, septin subunit composition has functional consequences on filament properties and cell morphogenesis. Small sequence differences elicit distinct biophysical properties and cell functions of septins, illuminating how gene duplication could be a driving force for septin gene expansions seen throughout the tree of life.
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Affiliation(s)
- Kevin S. Cannon
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Department of Biochemistry and Biophysics, University of North Carolina, Chapel Hill, NC, USA
| | - Jose M. Vargas-Muniz
- Microbiology Program, School of Biological Sciences, Southern Illinois University, Carbondale, IL, USA
| | - Neil Billington
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ian Seim
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Department of Applied Physical Sciences, University of North Carolina, Chapel Hill, NC, USA
- Curriculum in Bioinformatics and Computational Biology, University of North Carolina, Chapel Hill, NC, USA
| | - Joanne Ekena
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
| | - James R. Sellers
- Cell Biology and Physiology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Amy. S. Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, USA
- Marine Biological Laboratory, Woods Hole, MA, USA
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5
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Martins CS, Taveneau C, Castro-Linares G, Baibakov M, Buzhinsky N, Eroles M, Milanović V, Omi S, Pedelacq JD, Iv F, Bouillard L, Llewellyn A, Gomes M, Belhabib M, Kuzmić M, Verdier-Pinard P, Lee S, Badache A, Kumar S, Chandre C, Brasselet S, Rico F, Rossier O, Koenderink GH, Wenger J, Cabantous S, Mavrakis M. Human septins organize as octamer-based filaments and mediate actin-membrane anchoring in cells. J Cell Biol 2023; 222:213778. [PMID: 36562751 PMCID: PMC9802686 DOI: 10.1083/jcb.202203016] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 10/20/2022] [Accepted: 12/01/2022] [Indexed: 12/24/2022] Open
Abstract
Septins are cytoskeletal proteins conserved from algae and protists to mammals. A unique feature of septins is their presence as heteromeric complexes that polymerize into filaments in solution and on lipid membranes. Although animal septins associate extensively with actin-based structures in cells, whether septins organize as filaments in cells and if septin organization impacts septin function is not known. Customizing a tripartite split-GFP complementation assay, we show that all septins decorating actin stress fibers are octamer-containing filaments. Depleting octamers or preventing septins from polymerizing leads to a loss of stress fibers and reduced cell stiffness. Super-resolution microscopy revealed septin fibers with widths compatible with their organization as paired septin filaments. Nanometer-resolved distance measurements and single-protein tracking further showed that septin filaments are membrane bound and largely immobilized. Finally, reconstitution assays showed that septin filaments mediate actin-membrane anchoring. We propose that septin organization as octamer-based filaments is essential for septin function in anchoring and stabilizing actin filaments at the plasma membrane.
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Affiliation(s)
- Carla Silva Martins
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France.,Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, Toulouse, France
| | - Cyntia Taveneau
- Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia
| | - Gerard Castro-Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Mikhail Baibakov
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Nicolas Buzhinsky
- CNRS, INSERM, LAI, Turing Centre for Living Systems, Aix-Marseille Univ, Marseille, France>
| | - Mar Eroles
- CNRS, INSERM, LAI, Turing Centre for Living Systems, Aix-Marseille Univ, Marseille, France>
| | - Violeta Milanović
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR, Bordeaux, France
| | - Shizue Omi
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Jean-Denis Pedelacq
- Institut de Pharmacologie et de Biologie Structurale (IPBS), Université de Toulouse, CNRS, Université Toulouse III-Paul Sabatier (UPS), Toulouse, France
| | - Francois Iv
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Léa Bouillard
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Alexander Llewellyn
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Maxime Gomes
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Mayssa Belhabib
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Mira Kuzmić
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, Marseille, France
| | - Stacey Lee
- Department of Bioengineering, University of California, Berkeley, CA, USA
| | - Ali Badache
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, Marseille, France
| | - Sanjay Kumar
- Department of Bioengineering, University of California, Berkeley, CA, USA
| | | | - Sophie Brasselet
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Felix Rico
- CNRS, INSERM, LAI, Turing Centre for Living Systems, Aix-Marseille Univ, Marseille, France>
| | - Olivier Rossier
- University Bordeaux, CNRS, Interdisciplinary Institute for Neuroscience, IINS, UMR, Bordeaux, France
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, The Netherlands
| | - Jerome Wenger
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), INSERM, Université de Toulouse, UPS, CNRS, Toulouse, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, Marseille, France
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6
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Shi W, Cannon KS, Curtis BN, Edelmaier C, Gladfelter AS, Nazockdast E. Curvature sensing as an emergent property of multiscale assembly of septins. Proc Natl Acad Sci U S A 2023; 120:e2208253120. [PMID: 36716363 PMCID: PMC9963131 DOI: 10.1073/pnas.2208253120] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2022] [Accepted: 12/15/2022] [Indexed: 02/01/2023] Open
Abstract
The ability of cells to sense and communicate their shape is central to many of their functions. Much is known about how cells generate complex shapes, yet how they sense and respond to geometric cues remains poorly understood. Septins are GTP-binding proteins that localize to sites of micrometer-scale membrane curvature. Assembly of septins is a multistep and multiscale process, but it is unknown how these discrete steps lead to curvature sensing. Here, we experimentally examine the time-dependent binding of septins at different curvatures and septin bulk concentrations. These experiments unexpectedly indicated that septins' curvature preference is not absolute but rather is sensitive to the combinations of membrane curvatures present in a reaction, suggesting that there is competition between different curvatures for septin binding. To understand the physical underpinning of this result, we developed a kinetic model that connects septins' self-assembly and curvature-sensing properties. Our experimental and modeling results are consistent with curvature-sensitive assembly being driven by cooperative associations of septin oligomers in solution with the bound septins. When combined, the work indicates that septin curvature sensing is an emergent property of the multistep, multiscale assembly of membrane-bound septins. As a result, curvature preference is not absolute and can be modulated by changing the physicochemical and geometric parameters involved in septin assembly, including bulk concentration, and the available membrane curvatures. While much geometry-sensitive assembly in biology is thought to be guided by intrinsic material properties of molecules, this is an important example of how curvature sensing can arise from multiscale assembly of polymers.
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Affiliation(s)
- Wenzheng Shi
- Department of Applied Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Kevin S. Cannon
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Brandy N. Curtis
- Department of Biochemistry and Biophysics, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Christopher Edelmaier
- Department of Applied Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
| | - Amy S. Gladfelter
- Department of Biology, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
- Marine Biology Laboratory, Woods Hole, MA02543
| | - Ehssan Nazockdast
- Department of Applied Physical Sciences, The University of North Carolina at Chapel Hill, Chapel Hill, NC27599
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7
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Panagiotou TC, Chen A, Wilde A. An anillin-CIN85-SEPT9 complex promotes intercellular bridge maturation required for successful cytokinesis. Cell Rep 2022; 40:111274. [PMID: 36044846 DOI: 10.1016/j.celrep.2022.111274] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Revised: 07/17/2022] [Accepted: 08/05/2022] [Indexed: 11/20/2022] Open
Abstract
Cleavage of one cell into two is the most dramatic event in the life of a cell. Plasma membrane fission occurs within a narrow intercellular bridge (ICB) between the daughter cells, but the mechanisms underlying ICB formation and maturation are poorly understood. Here we identify CIN85 as an ICB assembly factor and demonstrate its requirement for robust and timely cytokinesis. CIN85 interacts directly with the N-terminal region of anillin and SEPT9 and thereby facilitates SEPT9-containing filament localization to the plasma membrane of the ICB. In contrast, the C-terminal pleckstrin homology (PH) domain of anillin binds to septin units lacking SEPT9 but enriched in SEPT11. Anillin's interactions with distinct septin units are required to promote ICB elongation and maturation that, we propose, generate the physical space into which the abscission machinery is recruited to drive the final membrane scission event releasing two independent daughter cells.
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Affiliation(s)
- Thomas C Panagiotou
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1M1, Canada
| | - Anan Chen
- Department of Biochemistry, University of Toronto, Toronto, ON M5S 1M1, Canada
| | - Andrew Wilde
- Department of Molecular Genetics, University of Toronto, Toronto, ON M5S 1M1, Canada; Department of Biochemistry, University of Toronto, Toronto, ON M5S 1M1, Canada.
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8
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Cavini IA, Leonardo DA, Rosa HVD, Castro DKSV, D'Muniz Pereira H, Valadares NF, Araujo APU, Garratt RC. The Structural Biology of Septins and Their Filaments: An Update. Front Cell Dev Biol 2021; 9:765085. [PMID: 34869357 PMCID: PMC8640212 DOI: 10.3389/fcell.2021.765085] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/27/2021] [Indexed: 01/22/2023] Open
Abstract
In order to fully understand any complex biochemical system from a mechanistic point of view, it is necessary to have access to the three-dimensional structures of the molecular components involved. Septins and their oligomers, filaments and higher-order complexes are no exception. Indeed, the spontaneous recruitment of different septin monomers to specific positions along a filament represents a fascinating example of subtle molecular recognition. Over the last few years, the amount of structural information available about these important cytoskeletal proteins has increased dramatically. This has allowed for a more detailed description of their individual domains and the different interfaces formed between them, which are the basis for stabilizing higher-order structures such as hexamers, octamers and fully formed filaments. The flexibility of these structures and the plasticity of the individual interfaces have also begun to be understood. Furthermore, recently, light has been shed on how filaments may bundle into higher-order structures by the formation of antiparallel coiled coils involving the C-terminal domains. Nevertheless, even with these advances, there is still some way to go before we fully understand how the structure and dynamics of septin assemblies are related to their physiological roles, including their interactions with biological membranes and other cytoskeletal components. In this review, we aim to bring together the various strands of structural evidence currently available into a more coherent picture. Although it would be an exaggeration to say that this is complete, recent progress seems to suggest that headway is being made in that direction.
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Affiliation(s)
- Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Higor V D Rosa
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Danielle K S V Castro
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.,São Carlos Institute of Chemistry, University of São Paulo, São Carlos, Brazil
| | | | | | - Ana P U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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9
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Kuzmić M, Linares GC, Fialová JL, Iv F, Salaün D, Llewellyn A, Gomes M, Belhabib M, Liu Y, Asano K, Rodrigues M, Isnardon D, Tachibana T, Koenderink GH, Badache A, Mavrakis M, Verdier-Pinard P. Septin-microtubule association via a motif unique to the isoform 1 of septin 9 tunes stress fibers. J Cell Sci 2021; 135:273936. [PMID: 34854883 DOI: 10.1242/jcs.258850] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2021] [Accepted: 11/19/2021] [Indexed: 10/19/2022] Open
Abstract
Septins, a family of GTP-binding proteins assembling into higher order structures, interface with the membrane, actin filaments and microtubules, which positions them as important regulators of cytoarchitecture. Septin 9 (SEPT9), which is frequently overexpressed in tumors and mutated in hereditary neuralgic amyotrophy (HNA), mediates the binding of septins to microtubules, but the molecular determinants of this interaction remained uncertain. We demonstrate that a short MAP-like motif unique to SEPT9 isoform 1 (SEPT9_i1) drives septin octamer-microtubule interaction in cells and in vitro reconstitutions. Septin-microtubule association requires polymerizable septin octamers harboring SEPT9_i1. Although outside of the MAP-like motif, HNA mutations abrogates this association, identifying a putative regulatory domain. Removal of this domain from SEPT9_i1 sequesters septins on microtubules, promotes microtubule stability and alters actomyosin fiber distribution and tension. Thus, we identify key molecular determinants and potential regulatory roles of septin-microtubule interaction, paving the way to deciphering the mechanisms underlying septin-associated pathologies.
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Affiliation(s)
- Mira Kuzmić
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Gerard Castro Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Jindřiška Leischner Fialová
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France.,Department of Pathological Physiology, Faculty of Medicine, Masaryk University, Brno, Czech Republic
| | - François Iv
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Danièle Salaün
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Alex Llewellyn
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Maxime Gomes
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Mayssa Belhabib
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Yuxiang Liu
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan
| | - Keisuke Asano
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan
| | - Magda Rodrigues
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Daniel Isnardon
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Taro Tachibana
- Department of Bioengineering, Graduate School of Engineering, Osaka City University, Osaka, Japan.,Cell Engineering Corporation, Osaka, Japan
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Ali Badache
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
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10
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Devlin L, Okletey J, Perkins G, Bowen JR, Nakos K, Montagna C, Spiliotis ET. Proteomic profiling of the oncogenic septin 9 reveals isoform-specific interactions in breast cancer cells. Proteomics 2021; 21:e2100155. [PMID: 34409731 DOI: 10.1002/pmic.202100155] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/05/2021] [Indexed: 02/06/2023]
Abstract
Septins are a family of multimeric GTP-binding proteins, which are abnormally expressed in cancer. Septin 9 (SEPT9) is an essential and ubiquitously expressed septin with multiple isoforms, which have differential expression patterns and effects in breast cancer cells. It is unknown, however, if SEPT9 isoforms associate with different molecular networks and functions. Here, we performed a proteomic screen in MCF-7 breast cancer cells to identify the interactome of GFP-SEPT9 isoforms 1, 4 and 5, which vary significantly in their N-terminal extensions. While all three isoforms associated with SEPT2 and SEPT7, the truncated SEPT9_i4 and SEPT9_i5 interacted with septins of the SEPT6 group more promiscuously than SEPT9_i1, which bound predominately SEPT8. Spatial mapping and functional clustering of non-septin partners showed isoform-specific differences in interactions with proteins of distinct subcellular organelles (e.g., nuclei, centrosomes, cilia) and functions such as cell signalling and ubiquitination. The interactome of the full length SEPT9_i1 was more enriched in cytoskeletal regulators, while the truncated SEPT9_i4 and SEPT9_i5 exhibited preferential and isoform-specific interactions with nuclear, signalling, and ubiquitinating proteins. These data provide evidence for isoform-specific interactions, which arise from truncations in the N-terminal extensions of SEPT9, and point to novel roles in the pathogenesis of breast cancer.
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Affiliation(s)
- Louis Devlin
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA.,Sanofi Pasteur, Swiftwater, Pennsylvania, USA
| | - Joshua Okletey
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | | | - Jonathan R Bowen
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Konstantinos Nakos
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Cristina Montagna
- Department of Radiology & Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
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11
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Iv F, Martins CS, Castro-Linares G, Taveneau C, Barbier P, Verdier-Pinard P, Camoin L, Audebert S, Tsai FC, Ramond L, Llewellyn A, Belhabib M, Nakazawa K, Di Cicco A, Vincentelli R, Wenger J, Cabantous S, Koenderink GH, Bertin A, Mavrakis M. Insights into animal septins using recombinant human septin octamers with distinct SEPT9 isoforms. J Cell Sci 2021; 134:jcs258484. [PMID: 34350965 DOI: 10.1242/jcs.258484] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023] Open
Abstract
Septin GTP-binding proteins contribute essential biological functions that range from the establishment of cell polarity to animal tissue morphogenesis. Human septins in cells form hetero-octameric septin complexes containing the ubiquitously expressed SEPT9 subunit (also known as SEPTIN9). Despite the established role of SEPT9 in mammalian development and human pathophysiology, biochemical and biophysical studies have relied on monomeric SEPT9, thus not recapitulating its native assembly into hetero-octameric complexes. We established a protocol that enabled, for the first time, the isolation of recombinant human septin octamers containing distinct SEPT9 isoforms. A combination of biochemical and biophysical assays confirmed the octameric nature of the isolated complexes in solution. Reconstitution studies showed that octamers with either a long or a short SEPT9 isoform form filament assemblies, and can directly bind and cross-link actin filaments, raising the possibility that septin-decorated actin structures in cells reflect direct actin-septin interactions. Recombinant SEPT9-containing octamers will make it possible to design cell-free assays to dissect the complex interactions of septins with cell membranes and the actin and microtubule cytoskeleton.
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Affiliation(s)
- Francois Iv
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Carla Silva Martins
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Gerard Castro-Linares
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
| | - Cyntia Taveneau
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
- ARC Centre of Excellence in Advanced Molecular Imaging, Monash University, Australia; Biomedicine Discovery Institute, Department of Biochemistry and Molecular Biology, Monash University, 3800 Clayton, Australia
| | - Pascale Barbier
- Aix-Marseille Univ, CNRS, UMR 7051, Institut de Neurophysiopathologie (INP), 13005 Marseille, France
| | - Pascal Verdier-Pinard
- Centre de Recherche en Cancérologie de Marseille (CRCM), INSERM, Institut Paoli-Calmettes, Aix Marseille Univ, CNRS, 13009 Marseille, France
| | - Luc Camoin
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Stéphane Audebert
- Aix-Marseille Univ, INSERM, CNRS, Institut Paoli-Calmettes, CRCM, Marseille Protéomique, Marseille, France
| | - Feng-Ching Tsai
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Laurie Ramond
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Alex Llewellyn
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Mayssa Belhabib
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Koyomi Nakazawa
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Aurélie Di Cicco
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Renaud Vincentelli
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS UMR7257, Aix Marseille Univ, 13009 Marseille, France
| | - Jerome Wenger
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
| | - Stéphanie Cabantous
- Centre de Recherche en Cancérologie de Toulouse (CRCT), Inserm, Université Paul Sabatier-Toulouse III, CNRS, 31037 Toulouse, France
| | - Gijsje H Koenderink
- Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, 2629 HZ Delft, The Netherlands
- Department of Living Matter, AMOLF, 1098 XG Amsterdam, The Netherlands
| | - Aurélie Bertin
- Institut Curie, Université PSL, Sorbonne Université, CNRS UMR 168, Laboratoire Physico Chimie Curie, 75005 Paris, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS UMR7249, Aix Marseille Univ, Centrale Marseille, 13013 Marseille, France
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12
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Spiliotis ET, McMurray MA. Masters of asymmetry - lessons and perspectives from 50 years of septins. Mol Biol Cell 2021; 31:2289-2297. [PMID: 32991244 PMCID: PMC7851956 DOI: 10.1091/mbc.e19-11-0648] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Septins are a unique family of GTPases, which were discovered 50 years ago as essential genes for the asymmetric cell shape and division of budding yeast. Septins assemble into filamentous nonpolar polymers, which associate with distinct membrane macrodomains and subpopulations of actin filaments and microtubules. While structurally a cytoskeleton-like element, septins function predominantly as spatial regulators of protein localization and interactions. Septin scaffolds and barriers have provided a long-standing paradigm for the generation and maintenance of asymmetry in cell membranes. Septins also promote asymmetry by regulating the spatial organization of the actin and microtubule cytoskeleton, and biasing the directionality of membrane traffic. In this 50th anniversary perspective, we highlight how septins have conserved and adapted their roles as effectors of membrane and cytoplasmic asymmetry across fungi and animals. We conclude by outlining principles of septin function as a module of symmetry breaking, which alongside the monomeric small GTPases provides a core mechanism for the biogenesis of molecular asymmetry and cell polarity.
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Affiliation(s)
| | - Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045
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13
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Abstract
Septins are an integral component of the cytoskeleton, assembling into higher-order oligomers and filamentous polymers that associate with actin filaments, microtubules and membranes. Here, we review septin interactions with actin and microtubules, and septin-mediated regulation of the organization and dynamics of these cytoskeletal networks, which is critical for cellular morphogenesis. We discuss how actomyosin-associated septins function in cytokinesis, cell migration and host defense against pathogens. We highlight newly emerged roles of septins at the interface of microtubules and membranes with molecular motors, which point to a 'septin code' for the regulation of membrane traffic. Additionally, we revisit the functions of microtubule-associated septins in mitosis and meiosis. In sum, septins comprise a unique module of cytoskeletal regulators that are spatially and functionally specialized and have properties of bona fide actin-binding and microtubule-associated proteins. With many questions still outstanding, the study of septins will continue to provide new insights into fundamental problems of cytoskeletal organization and function.
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14
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Soroor F, Kim MS, Palander O, Balachandran Y, Collins RF, Benlekbir S, Rubinstein JL, Trimble WS. Revised subunit order of mammalian septin complexes explains their in vitro polymerization properties. Mol Biol Cell 2020; 32:289-300. [PMID: 33263440 PMCID: PMC8098831 DOI: 10.1091/mbc.e20-06-0398] [Citation(s) in RCA: 41] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Septins are conserved GTP-binding cytoskeletal proteins that polymerize into filaments by end-to-end joining of hetero-oligomeric complexes. In human cells, both hexamers and octamers exist, and crystallography studies predicted the order of the hexamers to be SEPT7-SEPT6-SEPT2-SEPT2-SEPT6-SEPT7, while octamers are thought to have the same core, but with SEPT9 at the ends. However, based on this septin organization, octamers and hexamers would not be expected to copolymerize due to incompatible ends. Here we isolated hexamers and octamers of specific composition from human cells and show that hexamers and octamers polymerize individually and, surprisingly, with each other. Binding of the Borg homology domain 3 (BD3) domain of Borg3 results in distinctive clustering of each filament type. Moreover, we show that the organization of hexameric and octameric complexes is inverted compared with its original prediction. This revised septin organization is congruent with the organization and behavior of yeast septins suggesting that their properties are more conserved than was previously thought.
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Affiliation(s)
- Forooz Soroor
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5G 1A8, Canada
| | - Moshe S Kim
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Oliva Palander
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5G 1A8, Canada
| | - Yadu Balachandran
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Richard F Collins
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - Samir Benlekbir
- Molecular Medicine Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada
| | - John L Rubinstein
- Molecular Medicine Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5G 1A8, Canada
| | - William S Trimble
- Cell Biology Program, Hospital for Sick Children, Toronto, ON M5G 1X8, Canada.,Department of Biochemistry, University of Toronto, Toronto, ON M5G 1A8, Canada
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15
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DeRose BT, Kelley RS, Ravi R, Kokona B, Beld J, Spiliotis ET, Padrick SB. Production and analysis of a mammalian septin hetero-octamer complex. Cytoskeleton (Hoboken) 2020; 77:485-499. [PMID: 33185030 DOI: 10.1002/cm.21643] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Revised: 10/26/2020] [Accepted: 11/08/2020] [Indexed: 01/19/2023]
Abstract
The septins are filament-forming proteins found in diverse eukaryotes from fungi to vertebrates, with roles in cytokinesis, shaping of membranes and modifying cytoskeletal organization. These GTPases assemble into rod-shaped soluble hetero-hexamers and hetero-octamers in mammals, which polymerize into filaments and higher order structures. While the cell biology and pathobiology of septins are advancing rapidly, mechanistic study of the mammalian septins is limited by a lack of recombinant hetero-octamer materials. We describe here the production and characterization of a recombinant mammalian septin hetero-octamer of defined stoichiometry, the SEPT2/SEPT6/SEPT7/SEPT3 complex. Using a fluorescent protein fusion to the complex, we observed filaments assembled from this complex. In addition, we used this novel tool to resolve recent questions regarding the organization of the soluble septin complex. Biochemical characterization of a SEPT3 truncation that disrupts SEPT3-SEPT3 interactions is consistent with SEPT3 occupying a central position in the complex while the SEPT2 subunits are at the ends of the rod-shaped octameric complexes. Consistent with SEPT2 being on the complex ends, we find that our purified SEPT2/SEPT6/SEPT7/SEPT3 hetero-octamer copolymerizes into mixed filaments with separately purified SEPT2/SEPT6/SEPT7 hetero-hexamer. We expect this new recombinant production approach to lay essential groundwork for future studies into mammalian septin mechanism and function.
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Affiliation(s)
- Barry T DeRose
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Robert S Kelley
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, Pennsylvania, USA.,VCU Health System, Richmond, Virginia, USA
| | - Roshni Ravi
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, Pennsylvania, USA.,WuXi Advanced Therapies, Philadelphia, Pennsylvania, USA
| | - Bashkim Kokona
- Department of Chemistry, Haverford College, Haverford, Pennsylvania, USA
| | - Joris Beld
- Department of Microbiology and Immunology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Shae B Padrick
- Department of Biochemistry and Molecular Biology, Drexel University, Philadelphia, Pennsylvania, USA
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16
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Farkašovský M. Septin architecture and function in budding yeast. Biol Chem 2020; 401:903-919. [PMID: 31913844 DOI: 10.1515/hsz-2019-0401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 12/28/2019] [Indexed: 01/22/2023]
Abstract
The septins constitute a conserved family of guanosine phosphate-binding and filament-forming proteins widespread across eukaryotic species. Septins appear to have two principal functions. One is to form a cortical diffusion barrier, like the septin collar at the bud neck of Saccharomyces cerevisiae, which prevents movement of membrane-associated proteins between the mother and daughter cells. The second is to serve as a polymeric scaffold for recruiting the proteins required for critical cellular processes to particular subcellular areas. In the last decade, structural information about the different levels of septin organization has appeared, but crucial structural determinants and factors responsible for septin assembly remain largely unknown. This review highlights recent findings on the architecture and function of septins and their remodeling with an emphasis on mitotically dividing budding yeasts.
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Affiliation(s)
- Marian Farkašovský
- Department of Biochemistry and Protein Structure, Institute of Molecular Biology SAS, Dubravska cesta 21, 84551 Bratislava, Slovak Republic
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17
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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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18
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Nakos K, Radler MR, Spiliotis ET. Septin 2/6/7 complexes tune microtubule plus-end growth and EB1 binding in a concentration- and filament-dependent manner. Mol Biol Cell 2019; 30:2913-2928. [PMID: 31577529 PMCID: PMC6822581 DOI: 10.1091/mbc.e19-07-0362] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Septins (SEPTs) are filamentous guanosine-5′-triphosphate (GTP)-binding proteins, which affect microtubule (MT)-dependent functions including membrane trafficking and cell division, but their precise role in MT dynamics is poorly understood. Here, in vitro reconstitution of MT dynamics with SEPT2/6/7, the minimal subunits of septin heteromers, shows that SEPT2/6/7 has a biphasic concentration-dependent effect on MT growth. Lower concentrations of SEPT2/6/7 enhance MT plus-end growth and elongation, while higher and intermediate concentrations inhibit and pause plus-end growth, respectively. We show that SEPT2/6/7 has a modest preference for GTP- over guanosine diphosphate (GDP)-bound MT lattice and competes with end-binding protein 1 (EB1) for binding to guanosine 5′-O-[γ-thio]triphosphate (GTPγS)-stabilized MTs, which mimic the EB1-preferred GDP-Pi state of polymerized tubulin. Strikingly, SEPT2/6/7 triggers EB1 dissociation from plus-end tips in cis by binding to the MT lattice and in trans when MT plus ends collide with SEPT2/6/7 filaments. At these intersections, SEPT2/6/7 filaments were more potent barriers than actin filaments in pausing MT growth and dissociating EB1 in vitro and in live cells. These data demonstrate that SEPT2/6/7 complexes and filaments can directly impact MT plus-end growth and the tracking of plus end–binding proteins and thereby may facilitate the capture of MT plus ends at intracellular sites of septin enrichment.
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Affiliation(s)
| | - Megan R Radler
- Department of Biology, Drexel University, Philadelphia, PA 19104
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19
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Fragoza R, Das J, Wierbowski SD, Liang J, Tran TN, Liang S, Beltran JF, Rivera-Erick CA, Ye K, Wang TY, Yao L, Mort M, Stenson PD, Cooper DN, Wei X, Keinan A, Schimenti JC, Clark AG, Yu H. Extensive disruption of protein interactions by genetic variants across the allele frequency spectrum in human populations. Nat Commun 2019; 10:4141. [PMID: 31515488 PMCID: PMC6742646 DOI: 10.1038/s41467-019-11959-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2019] [Accepted: 08/06/2019] [Indexed: 12/19/2022] Open
Abstract
Each human genome carries tens of thousands of coding variants. The extent to which this variation is functional and the mechanisms by which they exert their influence remains largely unexplored. To address this gap, we leverage the ExAC database of 60,706 human exomes to investigate experimentally the impact of 2009 missense single nucleotide variants (SNVs) across 2185 protein-protein interactions, generating interaction profiles for 4797 SNV-interaction pairs, of which 421 SNVs segregate at > 1% allele frequency in human populations. We find that interaction-disruptive SNVs are prevalent at both rare and common allele frequencies. Furthermore, these results suggest that 10.5% of missense variants carried per individual are disruptive, a higher proportion than previously reported; this indicates that each individual's genetic makeup may be significantly more complex than expected. Finally, we demonstrate that candidate disease-associated mutations can be identified through shared interaction perturbations between variants of interest and known disease mutations.
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Affiliation(s)
- Robert Fragoza
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jishnu Das
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, 02139, USA
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Shayne D Wierbowski
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Jin Liang
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Tina N Tran
- Department of Biomedical Science, Cornell University, Ithaca, NY, 14853, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Siqi Liang
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Juan F Beltran
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Christen A Rivera-Erick
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Kaixiong Ye
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Ting-Yi Wang
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Li Yao
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Matthew Mort
- Institute of Medical Genetics, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Peter D Stenson
- Institute of Medical Genetics, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - David N Cooper
- Institute of Medical Genetics, Cardiff University, Heath Park, Cardiff, CF14 4XN, UK
| | - Xiaomu Wei
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
| | - Alon Keinan
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
| | - John C Schimenti
- Department of Biomedical Science, Cornell University, Ithaca, NY, 14853, USA
| | - Andrew G Clark
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Haiyuan Yu
- Department of Computational Biology, Cornell University, Ithaca, NY, 14853, USA.
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY, 14853, USA.
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20
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McMurray MA, Thorner J. Turning it inside out: The organization of human septin heterooligomers. Cytoskeleton (Hoboken) 2019; 76:449-456. [PMID: 31614074 PMCID: PMC6872917 DOI: 10.1002/cm.21571] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Revised: 10/02/2019] [Accepted: 10/08/2019] [Indexed: 01/09/2023]
Abstract
Septin family proteins are quite similar to each other both within and between eukaryotic species. Typically, multiple discrete septins co-assemble into linear heterooligomers (usually hexameric or octameric rods) with a variety of cellular functions. We know little about how incorporation of different septins confers different properties to such complexes. This issue is especially acute in human cells where 13 separate septin gene products (often produced in multiple forms arising from alternative start codons and differential splicing) are expressed in a tissue-specific manner. Based on sequence alignments and phylogenetic criteria, human septins fall into four distinct groups predictive of their interactions, that is, members of the same group appear to occupy the same position within oligomeric septin protomers, which are "palindromic" (have twofold rotational symmetry about a central homodimeric pair). Many such protomers are capable of end-to-end polymerization, generating filaments. Over a decade ago, a study using X-ray crystallography and single-particle electron microscopy deduced the arrangement within recombinant heterohexamers comprising representatives of three human septin groups-SEPT2, SEPT6, and SEPT7. This model greatly influenced subsequent studies of human and other septin complexes, including how incorporating a septin from a fourth group forms heterooctamers, as first observed in budding yeast. Two recent studies, including one in this issue of Cytoskeleton, provide clear evidence that, in fact, the organization of subunits within human septin heterohexamers and heterooctamers is inverted relative to the original model. These findings are discussed here in a broader context, including possible causes for the initial confusion.
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Affiliation(s)
- Michael A McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics & Structural Biology, University of California, Berkeley, California
- Division of Cell & Developmental Biology, University of California, Berkeley, California
- Department of Molecular and Cell Biology, University of California, Berkeley, California
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21
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D'Amore C, Salizzato V, Borgo C, Cesaro L, Pinna LA, Salvi M. A Journey through the Cytoskeleton with Protein Kinase CK2. Curr Protein Pept Sci 2019; 20:547-562. [PMID: 30659536 DOI: 10.2174/1389203720666190119124846] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2018] [Revised: 12/21/2018] [Accepted: 01/09/2019] [Indexed: 01/15/2023]
Abstract
Substrate pleiotropicity, a very acidic phosphorylation consensus sequence, and an apparent uncontrolled activity, are the main features of CK2, a Ser/Thr protein kinase that is required for a plethora of cell functions. Not surprisingly, CK2 appears to affect cytoskeletal structures and correlated functions such as cell shape, mechanical integrity, cell movement and division. This review outlines our current knowledge of how CK2 regulates cytoskeletal structures, and discusses involved pathways and molecular mechanisms.
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Affiliation(s)
- Claudio D'Amore
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Valentina Salizzato
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Christian Borgo
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Luca Cesaro
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
| | - Lorenzo A Pinna
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy.,CNR Institute of Neurosciences, Via U. Bassi 58/B, Padova, Italy
| | - Mauro Salvi
- Department of Biomedical Sciences, University of Padova, Via U. Bassi 58/B, Padova, Italy
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A blueprint of septin expression in human tissues. Funct Integr Genomics 2019; 19:787-797. [PMID: 31089837 DOI: 10.1007/s10142-019-00690-3] [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: 02/22/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 12/29/2022]
Abstract
Septins are GTP-binding proteins that polymerize to form filaments involved in several important biological processes. In human, 13 distinct septins genes are classified in four groups. Filaments formed by septins are complex and usually involve members of each group in specific positions. Expression data from GTEx database, a publicly available expression database with thousands of samples derived from multiple human tissues, was used to evaluate the expression of septins. The brain is noticeably a hotspot for septin expression where few genes contribute to a large portion of septin transcript pool. Co-expression data between septins suggests two predominant specific complexes in brain tissues and one filament in other tissues. SEPT3 and SEPT5 are two genes highly expressed in the brain and with a strong co-expression in all brain tissues. Additional analysis shows that the expression of these two genes is highly variable between individuals, but significantly dependent on the individual's age. Age-dependent decrease of expression from those two septins involved in synapses reinforces their possible link with cognitive decay and neurodegenerative diseases associated with aging. Analysis of enrichment of Gene Ontology terms from lists of genes consistently co-expressed with septins suggests participation in diverse biological processes, pointing out some novel roles for septins. Interestingly, we observed strong consistency of some of these terms with experimentally described roles of septins. Coordination of septins expression with genes involved in DNA repair and cell cycle control may provide insights for previously described links between septins and cancer.
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Septin filament coalignment with microtubules depends on SEPT9_i1 and tubulin polyglutamylation, and is an early feature of acquired cell resistance to paclitaxel. Cell Death Dis 2019; 10:54. [PMID: 30670682 PMCID: PMC6342940 DOI: 10.1038/s41419-019-1318-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 12/14/2018] [Accepted: 12/18/2018] [Indexed: 02/06/2023]
Abstract
Cancer cell resistance to taxanes is a complex, multifactorial process, which results from the combination of several molecular and cellular changes. In breast cancer cells adapted to long-term paclitaxel treatment, we previously identified a new adaptive mechanism that contributes to resistance and involves high levels of tubulin tyrosination and long-chain polyglutamylation coupled with high levels of septin expression, especially that of SEPT9_i1. This in turn led to higher CLIP-170 and MCAK recruitment to microtubules to enhance microtubule dynamics and therefore counteract the stabilizing effects of taxanes. Here, we explored to which extent this new mechanism alone could trigger taxane resistance. We show that coupling septins (including SEPT9_i1) overexpression together with long-chain tubulin polyglutamylation induce significant paclitaxel resistance in several naive (taxane-sensitive) cell lines and accordingly stimulate the binding of CLIP-170 and MCAK to microtubules. Strikingly, such resistance was paralleled by a systematic relocalization of septin filaments from actin fibers to microtubules. We further show that this relocalization resulted from the overexpression of septins in a context of enhanced tubulin polyglutamylation and reveal that it could also be promoted by an acute treatment with paclitaxel of sensitve cell displaying a high basal level of SEPT9_i1. These findings point out the functional importance and the complex cellular dynamics of septins in the onset of cell resistance to death caused by microtubule-targeting antimitotic drugs of the taxane family.
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Neubauer K, Neubauer B, Seidl M, Zieger B. Characterization of septin expression in normal and fibrotic kidneys. Cytoskeleton (Hoboken) 2018; 76:143-153. [PMID: 30019536 DOI: 10.1002/cm.21473] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Revised: 06/18/2018] [Accepted: 06/19/2018] [Indexed: 01/22/2023]
Abstract
Chronic kidney disease (CKD) is characterized by the loss of nephrons and worsening organ-fibrosis that leads to deterioration and ultimately the total breakdown of kidney function. Renal fibrosis has become a major public health problem worldwide and necessitates hemodialysis and kidney transplantation in affected patients. CKD is mainly characterized by the activation and proliferation of interstitial fibroblasts and by excessive synthesis and accumulation of extracellular matrix components, causing the disruption of the normal tissue architecture of the kidney. Septins are GTPase proteins associated with membranes, actin filaments, and microtubules and are undoubtedly crucial for cytoskeleton organization. Although some septins are involved in liver fibrosis, they have not been investigated in the context of renal fibrosis. Here, we show that numerous septins are expressed in the healthy kidney and demonstrate in fibrotic mouse kidneys that various septins are remarkably up-regulated in the tubulointerstitium compared to contralateral control kidneys. We observed the same findings in human fibrotic kidneys. In both healthy and fibrotic kidneys, septins are coexpressed with extracellular matrix components, reinforcing the structural function of septins as cytoskeletal components. Furthermore, we could show in septin 8-deficient mice that septin 8 is dispensable for the formation of renal fibrosis, and that no other septin was compensatory changed in kidneys compared to wild-type mice.
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Affiliation(s)
- Katharina Neubauer
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Bjoern Neubauer
- Institute of Physiology, University of Regensburg, Regensburg, Germany
| | - Maximilian Seidl
- Faculty of Medicine, Medical Center, Institute of Clinical Pathology, University of Freiburg, Freiburg, Germany
| | - Barbara Zieger
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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25
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Vissa A, Giuliani M, Froese CD, Kim MS, Soroor F, Kim PK, Trimble WS, Yip CM. Single‐molecule localization microscopy of septin bundles in mammalian cells. Cytoskeleton (Hoboken) 2018; 76:63-72. [DOI: 10.1002/cm.21481] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 07/04/2018] [Accepted: 07/16/2018] [Indexed: 12/25/2022]
Affiliation(s)
- Adriano Vissa
- Institute of Biomaterials and Biomedical EngineeringUniversity of Toronto Toronto Ontario Canada
- Donnelly Centre for Cellular and Biomolecular ResearchUniversity of Toronto Toronto Ontario Canada
| | - Maximiliano Giuliani
- Institute of Biomaterials and Biomedical EngineeringUniversity of Toronto Toronto Ontario Canada
- Donnelly Centre for Cellular and Biomolecular ResearchUniversity of Toronto Toronto Ontario Canada
| | - Carol D. Froese
- Program in Cell BiologyThe Hospital for Sick Children Toronto Ontario Canada
| | - Moshe S. Kim
- Program in Cell BiologyThe Hospital for Sick Children Toronto Ontario Canada
| | - Forooz Soroor
- Program in Cell BiologyThe Hospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
| | - Peter K. Kim
- Program in Cell BiologyThe Hospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
| | - William S. Trimble
- Program in Cell BiologyThe Hospital for Sick Children Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
- Department of PhysiologyUniversity of Toronto Toronto Ontario Canada
| | - Christopher M. Yip
- Institute of Biomaterials and Biomedical EngineeringUniversity of Toronto Toronto Ontario Canada
- Donnelly Centre for Cellular and Biomolecular ResearchUniversity of Toronto Toronto Ontario Canada
- Department of BiochemistryUniversity of Toronto Toronto Ontario Canada
- Department of Chemical Engineering and Applied ChemistryUniversity of Toronto Toronto Ontario Canada
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26
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Septins are critical regulators of osteoclastic bone resorption. Sci Rep 2018; 8:13016. [PMID: 30158637 PMCID: PMC6115361 DOI: 10.1038/s41598-018-31159-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2018] [Accepted: 08/07/2018] [Indexed: 12/23/2022] Open
Abstract
Septins are known to play key roles in supporting cytoskeletal stability, vesicular transport, endo-/exocytosis, stabilizing cellular membranes and forming diffusion barriers. Their function in mammalian cells is poorly investigated. The osteoclast offers an interesting tool to investigate septins because all cellular activities septins were reported to be involved in are critical for osteoclasts. However, the existence of septins in osteoclasts has not even been reported. Here we show that the SEPT9 gene and Septin 9 (SEPT9) protein are expressed and synthesized during differentiation of human osteoclasts. Pharmacological stabilization of septin filaments dose dependently inhibits bone resorption of human osteoclasts in vitro suggesting a role for septins in bone resorption. Attesting to this, conditional deletion of Sept9 in mice leads to elevated levels of trabecular bone and diminished femoral growth in vivo. Finally, systematic interrogation of the spatial organization of SEPT9 by confocal microscopy reveals that SEPT9 is closely associated to the structures known to be critical for osteoclast activity. We propose that septins in general and SEPT9 in particular play a previously unappreciated role in osteoclastic bone resorption.
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Deb BK, Hasan G. SEPT7-mediated regulation of Ca 2+ entry through Orai channels requires other septin subunits. Cytoskeleton (Hoboken) 2018; 76:104-114. [PMID: 30004181 DOI: 10.1002/cm.21476] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2018] [Revised: 06/21/2018] [Accepted: 07/06/2018] [Indexed: 11/12/2022]
Abstract
Orai channels are plasma membrane resident Ca2+ channels that allow extracellular Ca2+ uptake after depletion of ER-Ca2+ stores by a process called store-operated Ca2+ entry (SOCE). Septins of the SEPT2 subgroup act as positive regulators of SOCE in human nonexcitable cells. SEPT2 subgroup septins form the central core of hetero-hexameric or hetero-octameric complexes with SEPT6, SEPT7 and SEPT9 subgroup septins. The presence of fewer septin encoding genes coupled with ease of genetic manipulation allows for better understanding of septin subgroup function in Drosophila. Our earlier findings show that although dSEPT7 reduction does not alter Orai-mediated Ca2+ entry during SOCE, it results in constitutive activation of Orai channels in resting neurons. Here, we have investigated the role of other septin subgroup members in regulating Orai channel activation in Drosophila neurons by both cellular and functional assays. We show that dSEPT1, a SEPT2 subgroup septin can exist in a complex with dSEPT2 and dSEPT7 in the central nervous system (CNS) of Drosophila. Our findings suggest that the nature of septin filaments and heteromers obtained after reducing septins of different subgroups alters their ability to regulate Orai channel opening. The molecular mechanisms underlying this complex regulation of Orai function by septins require further cellular investigations.
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Affiliation(s)
- Bipan K Deb
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research, Bangalore, Karnataka, India
| | - Gaiti Hasan
- National Centre for Biological Sciences (NCBS), Tata Institute of Fundamental Research, Bangalore, Karnataka, India
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28
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Homoto S, Izawa S. Persistent actin depolarization caused by ethanol induces the formation of multiple small cortical septin rings in yeast. J Cell Sci 2018; 131:jcs.217091. [PMID: 29991513 DOI: 10.1242/jcs.217091] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2018] [Accepted: 07/03/2018] [Indexed: 11/20/2022] Open
Abstract
Short-term exposure to severe ethanol stress has adverse effects on yeast cells. However, limited information is available on the effects of long-term exposure to severe ethanol stress. In this study, we examined the effects of a long-term treatment with a high ethanol concentration [10% (v/v)] on yeast morphology. We found that long-term severe ethanol stress induced the continuous depolarization of the actin cytoskeleton and hypertrophy in yeast cells, accompanied by the aberrant localization of septins, which formed multiple small cortical rings (MSCRs). The formation of MSCRs was also induced by the continuous depolarization of the actin cytoskeleton caused by a treatment with latrunculin-A, an effective inhibitor of actin polymerization. Unlike the formation of conventional septin rings, the formation of MSCRs did not require Cdc42 and its effectors, Gic1, Gic2 and Cla4. These results provide novel insights into the effects of persistent actin depolarization caused by long-term exposure to severe ethanol stress on yeast cytomorphology.
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Affiliation(s)
- Sena Homoto
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
| | - Shingo Izawa
- Laboratory of Microbial Technology, Graduate School of Science and Technology, Kyoto Institute of Technology, Kyoto 606-8585, Japan
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29
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Spiliotis ET. Spatial effects - site-specific regulation of actin and microtubule organization by septin GTPases. J Cell Sci 2018; 131:jcs207555. [PMID: 29326311 PMCID: PMC5818061 DOI: 10.1242/jcs.207555] [Citation(s) in RCA: 79] [Impact Index Per Article: 13.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The actin and microtubule cytoskeletons comprise a variety of networks with distinct architectures, dynamics and protein composition. A fundamental question in eukaryotic cell biology is how these networks are spatially and temporally controlled, so they are positioned in the right intracellular places at the right time. While significant progress has been made in understanding the self-assembly of actin and microtubule networks, less is known about how they are patterned and regulated in a site-specific manner. In mammalian systems, septins are a large family of GTP-binding proteins that multimerize into higher-order structures, which associate with distinct subsets of actin filaments and microtubules, as well as membranes of specific curvature and lipid composition. Recent studies have shed more light on how septins interact with actin and microtubules, and raised the possibility that the cytoskeletal topology of septins is determined by their membrane specificity. Importantly, new functions have emerged for septins regarding the generation, maintenance and positioning of cytoskeletal networks with distinct organization and biochemical makeup. This Review presents new and past findings, and discusses septins as a unique regulatory module that instructs the local differentiation and positioning of distinct actin and microtubule networks.
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Affiliation(s)
- Elias T Spiliotis
- Drexel University, Department of Biology, Drexel University, Philadelphia, PA 19104, USA
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30
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Weems A, McMurray M. The step-wise pathway of septin hetero-octamer assembly in budding yeast. eLife 2017; 6. [PMID: 28541184 PMCID: PMC5461111 DOI: 10.7554/elife.23689] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Accepted: 05/24/2017] [Indexed: 01/22/2023] Open
Abstract
Septin proteins bind guanine nucleotides and form rod-shaped hetero-oligomers. Cells choose from a variety of available septins to assemble distinct hetero-oligomers, but the underlying mechanism was unknown. Using a new in vivo assay, we find that a stepwise assembly pathway produces the two species of budding yeast septin hetero-octamers: Cdc11/Shs1–Cdc12–Cdc3–Cdc10–Cdc10–Cdc3–Cdc12–Cdc11/Shs1. Rapid GTP hydrolysis by monomeric Cdc10 drives assembly of the core Cdc10 homodimer. The extended Cdc3 N terminus autoinhibits Cdc3 association with Cdc10 homodimers until prior Cdc3–Cdc12 interaction. Slow hydrolysis by monomeric Cdc12 and specific affinity of Cdc11 for transient Cdc12•GTP drive assembly of distinct trimers, Cdc11–Cdc12–Cdc3 or Shs1–Cdc12–Cdc3. Decreasing the cytosolic GTP:GDP ratio increases the incorporation of Shs1 vs Cdc11, which alters the curvature of filamentous septin rings. Our findings explain how GTP hydrolysis controls septin assembly, and uncover mechanisms by which cells construct defined septin complexes. DOI:http://dx.doi.org/10.7554/eLife.23689.001
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Affiliation(s)
- Andrew Weems
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
| | - Michael McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, United States
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Kaplan C, Steinmann M, Zapiorkowska NA, Ewers H. Functional Redundancy of Septin Homologs in Dendritic Branching. Front Cell Dev Biol 2017; 5:11. [PMID: 28265560 PMCID: PMC5316521 DOI: 10.3389/fcell.2017.00011] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2016] [Accepted: 02/06/2017] [Indexed: 01/02/2023] Open
Abstract
Septins are cytoskeletal GTPases present in nonpolar heteromeric complexes that assemble in a palindromic fashion from two to eight subunits. Mammalian septins function in several fundamental cellular processes at the membrane-cytoskeleton interface including dendritic branching in neurons. Sequence homology divides the 13 mammalian septin genes into four homology groups. Experimental findings suggest that septin function is redundant among septins from one homology group. This is best understood for the isoforms of the SEPT2 group, which form a homodimer at the center of septin complexes. In vitro, all SEPT2-group septins form recombinant hexameric complexes with two copies of SEPT6 and SEPT7. However, it remains unclear to what extent homologs septins can substitute for each other in specific cellular processes. Here, we use the experimental paradigm of dendritic branching in hippocampal rat neurons to ask, to what extent septins of the SEPT2-group are functionally redundant. Dendritic branching is significantly reduced when SEPT5 is downregulated. In neurons expressing SEPT5-shRNA, simultaneously expressed SEPT2-GFP, and SEPT4-GFP colocalize with SEPT7 at dendritic spine necks and rescue dendritic branching. In contrast, SEPT1-GFP is diffusely distributed in the cytoplasm in SEPT5 downregulated neurons and cannot rescue dendritic branching. Our findings provide a basis for the study of septin-specific functions in cells.
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Affiliation(s)
- Charlotte Kaplan
- Department of Biology, Institute of Biochemistry, University of ZurichZurich, Switzerland; Laboratory of Physical Chemistry, University of ZurichZurich, Switzerland
| | - Mayra Steinmann
- Department of Biology, Institute of Biochemistry, University of ZurichZurich, Switzerland; Laboratory of Physical Chemistry, University of ZurichZurich, Switzerland
| | - Natalia A Zapiorkowska
- Department of Biology, Institute of Biochemistry, University of ZurichZurich, Switzerland; Laboratory of Physical Chemistry, University of ZurichZurich, Switzerland
| | - Helge Ewers
- Department of Biology, Institute of Biochemistry, University of ZurichZurich, Switzerland; Laboratory of Physical Chemistry, University of ZurichZurich, Switzerland
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Abstract
Septins are GTP-binding and membrane-interacting proteins with a highly conserved domain structure involved in various cellular processes, including cytoskeleton organization, cytokinesis, and membrane dynamics. To date, 13 different septin genes have been identified in mammals (SEPT1 to SEPT12 and SEPT14), which can be classified into four distinct subgroups based on the sequence homology of their domain structure (SEPT2, SEPT3, SEPT6, and SEPT7 subgroup). The family members of these subgroups have a strong affinity for other septins and form apolar tri-, hexa-, or octameric complexes consisting of multiple septin polypeptides. The first characterized core complex is the hetero-trimer SEPT2-6-7. Within these complexes single septins can be exchanged in a subgroup-specific manner. Hexamers contain SEPT2 and SEPT6 subgroup members and SEPT7 in two copies each whereas the octamers additionally comprise two SEPT9 subgroup septins. The various isoforms seem to determine the function and regulation of the septin complex. Septins self-assemble into higher-order structures, including filaments and rings in orders, which are typical for different cell types. Misregulation of septins leads to human diseases such as neurodegenerative and bleeding disorders. In non-dividing cells such as neuronal tissue and platelets septins have been associated with exocytosis. However, many mechanistic details and roles attributed to septins are poorly understood. We describe here some important mammalian septin interactions with a special focus on the clinically relevant septin interactions.
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Affiliation(s)
- Katharina Neubauer
- Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg Freiburg, Germany
| | - Barbara Zieger
- Division of Pediatric Hematology and Oncology, Department of Pediatrics and Adolescent Medicine, Faculty of Medicine, Medical Center-University of Freiburg Freiburg, Germany
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Angelis D, Spiliotis ET. Septin Mutations in Human Cancers. Front Cell Dev Biol 2016; 4:122. [PMID: 27882315 PMCID: PMC5101219 DOI: 10.3389/fcell.2016.00122] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2016] [Accepted: 10/17/2016] [Indexed: 12/22/2022] Open
Abstract
Septins are GTP-binding proteins that are evolutionarily and structurally related to the RAS oncogenes. Septin expression levels are altered in many cancers and new advances point to how abnormal septin expression may contribute to the progression of cancer. In contrast to the RAS GTPases, which are frequently mutated and actively promote tumorigenesis, little is known about the occurrence and role of septin mutations in human cancers. Here, we review septin missense mutations that are currently in the Catalog of Somatic Mutations in Cancer (COSMIC) database. The majority of septin mutations occur in tumors of the large intestine, skin, endometrium and stomach. Over 25% of the annotated mutations in SEPT2, SEPT4, and SEPT9 belong to large intestine tumors. From all septins, SEPT9 and SEPT14 exhibit the highest mutation frequencies in skin, stomach and large intestine cancers. While septin mutations occur with frequencies lower than 3%, recurring mutations in several invariant and highly conserved amino acids are found across different septin paralogs and tumor types. Interestingly, a significant number of these mutations occur in the GTP-binding pocket and septin dimerization interfaces. Future studies may determine how these somatic mutations affect septin structure and function, whether they contribute to the progression of specific cancers and if they could serve as tumor-specific biomarkers.
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Poüs C, Klipfel L, Baillet A. Cancer-Related Functions and Subcellular Localizations of Septins. Front Cell Dev Biol 2016; 4:126. [PMID: 27878118 PMCID: PMC5099157 DOI: 10.3389/fcell.2016.00126] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2016] [Accepted: 10/24/2016] [Indexed: 12/16/2022] Open
Abstract
Since the initial discovery of septin family GTPases, the understanding of their molecular organization and cellular roles keeps being refined. Septins have been involved in many physiological processes and the misregulation of specific septin gene expression has been implicated in diverse human pathologies, including neurological disorders and cancer. In this minireview, we focus on the importance of the subunit composition and subcellular localization of septins relevant to tumor initiation, progression, and metastasis. We especially underline the importance of septin polymer composition and of their association with the plasma membrane, actin, or microtubules in cell functions involved in cancer and in resistance to cancer therapies. Through their scaffolding role, their function in membrane compartmentalization or through their protective function against protein degradation, septins also emerge as critical organizers of membrane-associated proteins and of signaling pathways implicated in cancer-associated angiogenesis, apoptosis, polarity, migration, proliferation, and in metastasis. Also, the question as to which of the free monomers, hetero-oligomers, or filaments is the functional form of mammalian septins is raised and the control over their spatial and temporal localization is discussed. The increasing amount of crosstalks identified between septins and cellular signaling mediators reinforces the exciting possibility that septins could be new targets in anti-cancer therapies or in therapeutic strategies to limit drug resistance.
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Affiliation(s)
- Christian Poüs
- Institut National de la Santé et de la Recherche Médicale, UMR-S 1193, Université Paris-Sud, Université Paris-SaclayChâtenay-Malabry, France; Laboratoire de Biochimie-Hormonologie, Hôpital Antoine Béclère, AP-HPClamart, France
| | - Laurence Klipfel
- Institut National de la Santé et de la Recherche Médicale, UMR-S 1193, Université Paris-Sud, Université Paris-SaclayChâtenay-Malabry, France; Département de Génétique, Institut de la Vision, Université Pierre et Marie Curie Paris 06, Sorbonne Universités, Institut National de la Santé et de la Recherche Médicale UMR-S 968, Centre National de la Recherche Scientifique UMR 7210Paris, France
| | - Anita Baillet
- Institut National de la Santé et de la Recherche Médicale, UMR-S 1193, Université Paris-Sud, Université Paris-Saclay Châtenay-Malabry, France
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Abstract
Polarized growth is critical for the development and maintenance of diverse organisms and tissues but particularly so in fungi, where nutrient uptake, communication, and reproduction all rely on cell asymmetries. To achieve polarized growth, fungi spatially organize both their cytosol and cortical membranes. Septins, a family of GTP-binding proteins, are key regulators of spatial compartmentalization in fungi and other eukaryotes. Septins form higher-order structures on fungal plasma membranes and are thought to contribute to the generation of cell asymmetries by acting as molecular scaffolds and forming diffusional barriers. Here we discuss the links between septins and polarized growth and consider molecular models for how septins contribute to cellular asymmetry in fungi.
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Affiliation(s)
- Anum Khan
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
| | - Molly McQuilken
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
| | - Amy S Gladfelter
- Department of Biological Sciences, Dartmouth College, Hanover, New Hampshire 03755;
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Ortore MG, Macedo JNA, Araujo APU, Ferrero C, Mariani P, Spinozzi F, Itri R. Structural and Thermodynamic Properties of Septin 3 Investigated by Small-Angle X-Ray Scattering. Biophys J 2016; 108:2896-902. [PMID: 26083929 DOI: 10.1016/j.bpj.2015.05.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2014] [Revised: 04/30/2015] [Accepted: 05/11/2015] [Indexed: 01/22/2023] Open
Abstract
Septins comprise a family of proteins involved in a variety of cellular processes and related to several human pathologies. They are constituted by three structural domains: the N- and C-terminal domains, highly variable in length and composition, and the central domain, involved in the guanine nucleotide (GTP) binding. Thirteen different human septins are known to form heterogeneous complexes or homofilaments, which are stabilized by specific interactions between the different interfaces present in the domains. In this work, we have investigated by in-solution small-angle x-ray scattering the structural and thermodynamic properties of a human septin 3 construct, SEPT3-GC, which contains both of both interfaces (G and NC) responsible for septin-septin interactions. In order to shed light on the role of these interactions, small-angle x-ray scattering measurements were performed in a wide range of temperatures, from 2 up to 56°C, both with and without a nonhydrolysable form of GTP (GTPγS). The acquired data show a temperature-dependent coexistence of monomers, dimers, and higher-order aggregates that were analyzed using a global fitting approach, taking into account the crystallographic structure of the recently reported SEPT3 dimer, PDB:3SOP. As a result, the enthalpy, entropy, and heat capacity variations that control the dimer-monomer dissociation equilibrium in solution were derived and GTPγS was detected to increase the enthalpic stability of the dimeric species. Moreover, a temperature increase was observed to induce dissociation of SEPT3-GC dimers into monomers just preceding their reassembling into amyloid aggregates, as revealed by the Thioflavin-T fluorescence assays.
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Affiliation(s)
- Maria Grazia Ortore
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy
| | - Joci N A Macedo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | - Ana Paula U Araujo
- Instituto de Física de São Carlos, Universidade de São Paulo, São Carlos, Brazil
| | | | - Paolo Mariani
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy
| | - Francesco Spinozzi
- Dipartimento di Scienze della Vita e dell'Ambiente and Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia, Università Politecnica delle Marche, Ancona, Italy.
| | - Rosangela Itri
- Instituto de Física da Universidade de São Paulo, São Paulo, Brazil.
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Finnigan GC, Takagi J, Cho C, Thorner J. Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 in Saccharomyces cerevisiae. Genetics 2015; 200:821-41. [PMID: 25971665 PMCID: PMC4512546 DOI: 10.1534/genetics.115.176495] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/08/2015] [Indexed: 02/07/2023] Open
Abstract
Septins are a family of GTP-binding proteins considered to be cytoskeletal elements because they self-assemble into filaments and other higher-order structures in vivo. In budding yeast, septins establish a diffusion barrier at the bud neck between a mother and daughter cell, promote membrane curvature there, and serve as a scaffold to recruit other proteins to the site of cytokinesis. However, the mechanism by which any septin engages a partner protein has been unclear. The two most related and recently evolved subunits appear to be Cdc11 and Shs1, and the basic building blocks for assembling septin structures are hetero-octameric rods (Cdc11-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Cdc11 and Shs1-Cdc12-Cdc3-Cdc10-Cdc10-Cdc3-Cdc12-Shs1). Loss of Cdc11 is not normally tolerated, whereas cells lacking Shs1 do not appear grossly abnormal. We established several different sensitized genetic backgrounds wherein Shs1 is indispensable, which allowed us to carry out the first comprehensive and detailed genetic analysis of Shs1 in vivo. Our analysis revealed several novel insights, including: (i) the sole portion of Shs1 essential for its function is a predicted coiled-coil-forming segment in its C-terminal extension (CTE); (ii) the CTE of Cdc11 shares this function; (iii) this role for the CTEs of Cdc11 and Shs1 is quite distinct from that of the CTEs of Cdc3 and Cdc12; and (iv) heterotypic Cdc11 and Shs1 junctions likely occur in vivo.
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Affiliation(s)
- Gregory C Finnigan
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202
| | - Julie Takagi
- Department of Microbiology and Immunology, University of California School of Medicine, San Francisco, California 94158-2200
| | - Christina Cho
- Harvard School of Dental Medicine, Boston, Massachusetts 02115
| | - Jeremy Thorner
- Division of Biochemistry, Biophysics and Structural Biology, Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202 Department of Microbiology and Immunology, University of California School of Medicine, San Francisco, California 94158-2200 Harvard School of Dental Medicine, Boston, Massachusetts 02115
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The Carboxy-Terminal Tails of Septins Cdc11 and Shs1 Recruit Myosin-II Binding Factor Bni5 to the Bud Neck in Saccharomyces cerevisiae. Genetics 2015; 200:843-62. [PMID: 25971666 DOI: 10.1534/genetics.115.176503] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2015] [Accepted: 05/08/2015] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Septins are a conserved family of GTP-binding proteins that form heterooctameric complexes that assemble into higher-order structures. In yeast, septin superstructure at the bud neck serves as a barrier to separate a daughter cell from its mother and as a scaffold to recruit the proteins that execute cytokinesis. However, how septins recruit specific factors has not been well characterized. In the accompanying article in this issue, (Finnigan et al. 2015), we demonstrated that the C-terminal extensions (CTEs) of the alternative terminal subunits of septin heterooctamers, Cdc11 and Shs1, share a role required for optimal septin function in vivo. Here we describe our use of unbiased genetic approaches (both selection of dosage suppressors and analysis of synthetic interactions) that pinpointed Bni5 as a protein that interacts with the CTEs of Cdc11 and Shs1. Furthermore, we used three independent methods-construction of chimeric proteins, noncovalent tethering mediated by a GFP-targeted nanobody, and imaging by fluorescence microscopy-to confirm that a physiologically important function of the CTEs of Cdc11 and Shs1 is optimizing recruitment of Bni5 and thereby ensuring efficient localization at the bud neck of Myo1, the type II myosin of the actomyosin contractile ring.Related article in GENETICS Finnigan, G. C. et al., 2015 Comprehensive Genetic Analysis of Paralogous Terminal Septin Subunits Shs1 and Cdc11 in Saccharomyces cerevisiae. Genetics 200: 841-861.
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Menon MB, Gaestel M. Sep(t)arate or not – how some cells take septin-independent routes through cytokinesis. J Cell Sci 2015; 128:1877-86. [PMID: 25690008 DOI: 10.1242/jcs.164830] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Cytokinesis is the final step of cell division, and is a process that requires a precisely coordinated molecular machinery to fully separate the cytoplasm of the parent cell and to establish the intact outer cell barrier of the daughter cells. Among various cytoskeletal proteins involved, septins are known to be essential mediators of cytokinesis. In this Commentary, we present recent observations that specific cell divisions can proceed in the absence of the core mammalian septin SEPT7 and its Drosophila homolog Peanut (Pnut) and that thus challenge the view that septins have an essential role in cytokinesis. In the pnut mutant neuroepithelium, orthogonal cell divisions are successfully completed. Similarly, in the mouse, Sept7-null mutant early embryonic cells and, more importantly, planktonically growing adult hematopoietic cells undergo productive proliferation. Hence, as discussed here, mechanisms must exist that compensate for the lack of SEPT7 and the other core septins in a cell-type-specific manner. Despite there being crucial non-canonical immune-relevant functions of septins, septin depletion is well tolerated by the hematopoietic system. Thus differential targeting of cytokinesis could form the basis for more specific anti-proliferative therapies to combat malignancies arising from cell types that require septins for cytokinesis, such as carcinomas and sarcomas, without impairing hematopoiesis that is less dependent on septin.
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Affiliation(s)
- Manoj B Menon
- Institute of Physiological Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Matthias Gaestel
- Institute of Physiological Chemistry, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Kuo YC, Shen YR, Chen HI, Lin YH, Wang YY, Chen YR, Wang CY, Kuo PL. SEPT12 orchestrates the formation of mammalian sperm annulus by organizing core octameric complexes with other SEPT proteins. J Cell Sci 2015; 128:923-34. [PMID: 25588830 DOI: 10.1242/jcs.158998] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
Male infertility has become a worldwide health problem, but the etiologies of most cases are still unknown. SEPT12, a GTP-binding protein, is involved in male fertility. Two SEPT12 mutations (SEPT12(T89M) and SEPT12(D197N)) have been identified in infertile men who have a defective sperm annulus with a bent tail. The function of SEPT12 in the sperm annulus is still unclear. Here, we found that SEPT12 formed a filamentous structure with SEPT7, SEPT 6, SEPT2 and SEPT4 at the sperm annulus. The SEPT12-based septin core complex was assembled as octameric filaments comprising the SEPT proteins 12-7-6-2-2-6-7-12 or 12-7-6-4-4-6-7-12. In addition, the GTP-binding domain of SEPT12 was crucial for its interaction with SEPT7, and the N- and C-termini of SEPT12 were required for the interaction of SEPT12 with itself to polymerize octamers into filaments. Mutant mice carrying the SEPT12(D197N) mutation, which disrupts SEPT12 filament formation, showed a disorganized sperm annulus, bent tail, reduced motility and loss of the SEPT ring structure at the sperm annulus. These phenotypes were also observed in an infertile man carrying SEPT12(D197N). Taken together, our results demonstrate the molecular architecture of SEPT12 filaments at the sperm annulus, their mechanical support of sperm motility, and their correlation with male infertility.
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Affiliation(s)
- Yung-Che Kuo
- Department of Biochemistry and Molecular Cell Biology, School of Medicine, College of Medicine, Taipei Medical University, Taipei 11031, Taiwan Graduate Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Yi-Ru Shen
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Hau-Inh Chen
- Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan Department of Research, Taipei Tzu Chi Hospital, Buddhist Tzu Chi Medical Foundation, New Taipei City 23142, Taiwan
| | - Ying-Hung Lin
- Graduate Institute of Basic Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City 24205, Taiwan
| | - Ya-Yun Wang
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Yet-Ran Chen
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 11529, Taiwan
| | - Chia-Yih Wang
- Graduate Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
| | - Pao-Lin Kuo
- Graduate Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan Department of Biochemistry and Molecular Biology, College of Medicine, National Cheng Kung University, Tainan 70403, Taiwan
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