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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Holley CL, Emming S, Monteleone MM, Mellacheruvu M, Kenney KM, Lawrence GMEP, Coombs JR, Burgener SS, Schroder K. The septin modifier, forchlorfenuron, activates NLRP3 via a potassium-independent mitochondrial axis. Cell Chem Biol 2024; 31:962-972.e4. [PMID: 38759620 DOI: 10.1016/j.chembiol.2024.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2023] [Revised: 04/07/2024] [Accepted: 04/19/2024] [Indexed: 05/19/2024]
Abstract
The Nod-like receptor protein 3 (NLRP3) inflammasome is activated by stimuli that induce perturbations in cell homeostasis, which commonly converge on cellular potassium efflux. NLRP3 has thus emerged as a sensor for ionic flux. Here, we identify forchlorfenuron (FCF) as an inflammasome activator that triggers NLRP3 signaling independently of potassium efflux. FCF triggers the rearrangement of septins, key cytoskeletal proteins that regulate mitochondrial function. We report that FCF triggered the rearrangement of SEPT2 into tubular aggregates and stimulated SEPT2-independent NLRP3 inflammasome signaling. Similar to imiquimod, FCF induced the collapse of the mitochondrial membrane potential and mitochondrial respiration. FCF thereby joins the imidazoquinolines as a structurally distinct class of molecules that triggers NLRP3 inflammasome signaling independent of potassium efflux, likely by inducing mitochondrial damage.
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Affiliation(s)
- Caroline L Holley
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
| | - Stefan Emming
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Mercedes M Monteleone
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Manasa Mellacheruvu
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kirsten M Kenney
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Grace M E P Lawrence
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Jared R Coombs
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Sabrina S Burgener
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD 4072, Australia.
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3
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Xu Y, Ding K, Peng T. Chemical Proteomics Reveals N ε-Fatty-Acylation of Septins by Rho Inactivation Domain (RID) of the Vibrio MARTX Toxin to Alter Septin Localization and Organization. Mol Cell Proteomics 2024; 23:100730. [PMID: 38311109 PMCID: PMC10924143 DOI: 10.1016/j.mcpro.2024.100730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/16/2024] [Accepted: 01/31/2024] [Indexed: 02/06/2024] Open
Abstract
Vibrio species, the Gram-negative bacterial pathogens causing cholera and sepsis, produce multiple secreted virulence factors for infection and pathogenesis. Among these is the multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin that releases several critical effector domains with distinct functions inside eukaryotic host cells. One such effector domain, the Rho inactivation domain (RID), has been discovered to catalyze long-chain Nε-fatty-acylation on lysine residues of Rho GTPases, causing inactivation of Rho GTPases and disruption of the host actin cytoskeleton. However, whether RID modifies other host proteins to exert additional functions remains to be determined. Herein, we describe the integration of bioorthogonal chemical labeling and quantitative proteomics to globally profile the target proteins modified by RID in living cells. More than 246 proteins are identified as new RID substrates, including many involved in GTPase regulation, cytoskeletal organization, and cell division. We demonstrate that RID extensively Nε-fatty-acylates septin proteins, the fourth cytoskeletal component of mammalian cells with important roles in diverse cellular processes. While affinity purification and mass spectrometry analysis show that RID-mediated Nε-fatty-acylation does not affect septin-septin interactions, this modification increases the membrane association of septins and confers localization to detergent-resistant membrane rafts. As a result, the filamentous assembly and organization of septins are disrupted by RID-mediated Nε-fatty-acylation, further contributing to cytoskeletal and mitotic defects that phenocopy the effects of septin depletion. Overall, our work greatly expands the substrate scope and function of RID and demonstrates the role of RID-mediated Nε-fatty-acylation in manipulating septin localization and organization.
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Affiliation(s)
- Yaxin Xu
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Ke Ding
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Tao Peng
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China; Shenzhen Bay Laboratory, Institute of Chemical Biology, Shenzhen, China.
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4
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Stjepić V, Nakamura M, Hui J, Parkhurst SM. Two Septin Complexes Mediate Actin Dynamics During Cell Wound Repair. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.11.14.567084. [PMID: 38014090 PMCID: PMC10680708 DOI: 10.1101/2023.11.14.567084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2023]
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, USA 98109
| | - Mitsutoshi Nakamura
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Justin Hui
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
| | - Susan M. Parkhurst
- Basic Sciences Division, Fred Hutchinson Cancer Center, Seattle, WA, USA 98109
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5
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Cavini IA, Winter AJ, D’Muniz Pereira H, Woolfson DN, Crump MP, Garratt RC. X-ray structure of the metastable SEPT14-SEPT7 coiled coil reveals a hendecad region crucial for heterodimerization. Acta Crystallogr D Struct Biol 2023; 79:881-894. [PMID: 37712436 PMCID: PMC10565730 DOI: 10.1107/s2059798323006514] [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: 05/11/2023] [Accepted: 07/27/2023] [Indexed: 09/16/2023] Open
Abstract
Septins are membrane-associated, GTP-binding proteins that are present in most eukaryotes. They polymerize to play important roles as scaffolds and/or diffusion barriers as part of the cytoskeleton. α-Helical coiled-coil domains are believed to contribute to septin assembly, and those observed in both human SEPT6 and SEPT8 form antiparallel homodimers. These are not compatible with their parallel heterodimeric organization expected from the current model for protofilament assembly, but they could explain the interfilament cross-bridges observed by microscopy. Here, the first structure of a heterodimeric septin coiled coil is presented, that between SEPT14 and SEPT7; the former is a SEPT6/SEPT8 homolog. This new structure is parallel, with two long helices that are axially shifted by a full helical turn with reference to their sequence alignment. The structure also has unusual knobs-into-holes packing of side chains. Both standard seven-residue (heptad) and the less common 11-residue (hendecad) repeats are present, creating two distinct regions with opposite supercoiling, which gives rise to an overall straight coiled coil. Part of the hendecad region is required for heterodimerization and therefore may be crucial for selective septin recognition. These unconventional sequences and structural features produce a metastable heterocomplex that nonetheless has enough specificity to promote correct protofilament assembly. For instance, the lack of supercoiling may facilitate unzipping and transitioning to the antiparallel homodimeric state.
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Affiliation(s)
- Italo A. Cavini
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Ashley J. Winter
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
| | - Humberto D’Muniz Pereira
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
| | - Derek N. Woolfson
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- School of Biochemistry, University of Bristol, Medical Sciences Building, University Walk, Bristol BS8 1TD, United Kingdom
- BrisSynBio, University of Bristol, School of Chemistry, Bristol BS8 1TS, United Kingdom
| | - Matthew P. Crump
- School of Chemistry, University of Bristol, Cantock’s Close, Bristol BS8 1TS, United Kingdom
- BrisSynBio, University of Bristol, School of Chemistry, Bristol BS8 1TS, United Kingdom
| | - Richard C. Garratt
- São Carlos Institute of Physics, University of São Paulo, Avenida João Dagnone 1100, São Carlos, SP 13563-120, Brazil
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6
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Suber Y, Alam MNA, Nakos K, Bhakt P, Spiliotis ET. Microtubule-associated septin complexes modulate kinesin and dynein motility with differential specificities. J Biol Chem 2023; 299:105084. [PMID: 37495111 PMCID: PMC10463263 DOI: 10.1016/j.jbc.2023.105084] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2023] [Revised: 06/27/2023] [Accepted: 07/14/2023] [Indexed: 07/28/2023] Open
Abstract
Long-range membrane traffic is guided by microtubule-associated proteins and posttranslational modifications, which collectively comprise a traffic code. The regulatory principles of this code and how it orchestrates the motility of kinesin and dynein motors are largely unknown. Septins are a large family of GTP-binding proteins, which assemble into complexes that associate with microtubules. Using single-molecule in vitro motility assays, we tested how the microtubule-associated SEPT2/6/7, SEPT2/6/7/9, and SEPT5/7/11 complexes affect the motilities of the constitutively active kinesins KIF5C and KIF1A and the dynein-dynactin-bicaudal D (DDB) motor complex. We found that microtubule-associated SEPT2/6/7 is a potent inhibitor of DDB and KIF5C, preventing mainly their association with microtubules. SEPT2/6/7 also inhibits KIF1A by obstructing stepping along microtubules. On SEPT2/6/7/9-coated microtubules, KIF1A inhibition is dampened by SEPT9, which alone enhances KIF1A, showing that individual septin subunits determine the regulatory properties of septin complexes. Strikingly, SEPT5/7/11 differs from SEPT2/6/7, in permitting the motility of KIF1A and immobilizing DDB to the microtubule lattice. In hippocampal neurons, filamentous SEPT5 colocalizes with somatodendritic microtubules that underlie Golgi membranes and lack SEPT6. Depletion of SEPT5 disrupts Golgi morphology and polarization of Golgi ribbons into the shaft of somato-proximal dendrites, which is consistent with the tethering of DDB to microtubules by SEPT5/7/11. Collectively, these results suggest that microtubule-associated complexes have differential specificities in the regulation of the motility and positioning of microtubule motors. We posit that septins are an integral part of the microtubule-based code that spatially controls membrane traffic.
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Affiliation(s)
- Yani Suber
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Md Noor A Alam
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Konstantinos Nakos
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Priyanka Bhakt
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA.
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7
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Szabó L, Telek A, Fodor J, Dobrosi N, Dócs K, Hegyi Z, Gönczi M, Csernoch L, Dienes B. Reduced Expression of Septin7 Hinders Skeletal Muscle Regeneration. Int J Mol Sci 2023; 24:13536. [PMID: 37686339 PMCID: PMC10487768 DOI: 10.3390/ijms241713536] [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: 06/05/2023] [Revised: 07/28/2023] [Accepted: 08/29/2023] [Indexed: 09/10/2023] Open
Abstract
Septins are considered the fourth component of the cytoskeleton with the septin7 isoform playing a critical role in the formation of diffusion barriers in phospholipid bilayers and intra- and extracellular scaffolds. While its importance has already been confirmed in different intracellular processes, very little is known about its role in skeletal muscle. Muscle regeneration was studied in a Sept7 conditional knock-down mouse model to prove the possible role of septin7 in this process. Sterile inflammation in skeletal muscle was induced which was followed by regeneration resulting in the upregulation of septin7 expression. Partial knock-down of Sept7 resulted in an increased number of inflammatory cells and myofibers containing central nuclei. Taken together, our data suggest that partial knock-down of Sept7 hinders the kinetics of muscle regeneration, indicating its crucial role in skeletal muscle functions.
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Affiliation(s)
- László Szabó
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- Doctoral School of Molecular Medicine, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Physiology Research Group, University of Debrecen, 4032 Debrecen, Hungary
| | - Andrea Telek
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Nóra Dobrosi
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Physiology Research Group, University of Debrecen, 4032 Debrecen, Hungary
| | - Klaudia Dócs
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Zoltán Hegyi
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
| | - Mónika Gönczi
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Physiology Research Group, University of Debrecen, 4032 Debrecen, Hungary
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
- ELKH-DE Cell Physiology Research Group, University of Debrecen, 4032 Debrecen, Hungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of Debrecen, 4032 Debrecen, Hungary
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8
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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: 3] [Impact Index Per Article: 3.0] [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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9
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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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10
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de Freitas Fernandes A, Leonardo DA, Cavini IA, Rosa HVD, Vargas JA, D'Muniz Pereira H, Nascimento AS, Garratt RC. Conservation and divergence of the G-interfaces of Drosophila melanogaster septins. Cytoskeleton (Hoboken) 2023; 80:153-168. [PMID: 36576069 DOI: 10.1002/cm.21740] [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: 11/26/2022] [Revised: 12/19/2022] [Accepted: 12/26/2022] [Indexed: 12/29/2022]
Abstract
Septins possess a conserved guanine nucleotide-binding (G) domain that participates in the stabilization of organized hetero-oligomeric complexes which assemble into filaments, rings and network-like structures. The fruit fly, Drosophila melanogaster, has five such septin genes encoding Sep1, Sep2, Sep4, Sep5 and Pnut. Here, we report the crystal structure of the heterodimer formed between the G-domains of Sep1 and Sep2, the first from an insect to be described to date. A G-interface stabilizes the dimer (in agreement with the expected arrangement for the Drosophila hexameric particle) and this bears significant resemblance to its human counterparts, even down to the level of individual amino acid interactions. On the other hand, a model for the G-interface formed between the two copies of Pnut which occupy the centre of the hexamer, shows important structural differences, including the loss of a highly favourable bifurcated salt-bridge network. Whereas wild-type Pnut purifies as a monomer, the reintroduction of the salt-bridge network results in stabilizing the dimeric interface in solution as shown by size exclusion chromatography and thermal stability measurements. Adaptive steered molecular dynamics reveals an unzipping mechanism for dimer dissociation which initiates at a point of electrostatic repulsion within the switch II region. Overall, the data contribute to a better understanding of the molecular interactions involved in septin assembly/disassembly.
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Affiliation(s)
| | | | | | | | - Jhon Antoni Vargas
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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11
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Perry JA, Werner ME, Rivenbark L, Maddox AS. Caenorhabditis elegans septins contribute to the development and structure of the oogenic germline. Cytoskeleton (Hoboken) 2023; 80:215-227. [PMID: 37265173 PMCID: PMC10524836 DOI: 10.1002/cm.21763] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2022] [Revised: 04/27/2023] [Accepted: 05/04/2023] [Indexed: 06/03/2023]
Abstract
Oocytes must be exceptionally large cells in order to support embryonic development. Throughout animal phylogeny, a specialized cell called a syncytium, wherein many nuclei share a continuous cytoplasm, achieves oogenesis. The syncytial nature of germline architecture is key to its function and depends on conserved components of the cortical cytoskeleton. Septins form non-polar cytoskeletal polymers that associate with membranes. In the syncytial germline of the nematode Caenorhabditis elegans, septins are highly enriched on the cortex and generally required for fertility, but the role of septins in the germline is poorly understood. We report that the C. elegans septins, UNC-59 and UNC-61, are important for germline extension during development, the maintenance of its syncytial architecture, and production of oocytes. While much of our findings substantiate the idea that the two C. elegans septins act together, we also found evidence that they have distinct functions. Loss of UNC-61 perturbed germline extension during germline development, while the loss of UNC-59 function severely affected germline architecture in adult hermaphrodites. Consultation of clustering results from a large-scale high-throughput screen suggested that septins are involved in germ cell proliferation and/or differentiation. In sum, our findings implicate a conserved cytoskeletal component in the complex architecture of a germline syncytium.
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Affiliation(s)
- Jenna A Perry
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Michael E Werner
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Larry Rivenbark
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Amy Shaub Maddox
- Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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12
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Carim SC, Hickson GR. The Rho1 GTPase controls anillo-septin assembly to facilitate contractile ring closure during cytokinesis. iScience 2023; 26:106903. [PMID: 37378349 PMCID: PMC10291328 DOI: 10.1016/j.isci.2023.106903] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 03/20/2023] [Accepted: 05/12/2023] [Indexed: 06/29/2023] Open
Abstract
Animal cell cytokinesis requires activation of the GTPase RhoA (Rho1 in Drosophila), which assembles an F-actin- and myosin II-dependent contractile ring (CR) at the equatorial plasma membrane. CR closure is poorly understood, but involves the multidomain scaffold protein, Anillin. Anillin binds many CR components including F-actin and myosin II (collectively actomyosin), RhoA and the septins. Anillin recruits septins to the CR but the mechanism is unclear. Live imaging of Drosophila S2 cells and HeLa cells revealed that the Anillin N-terminus, which scaffolds actomyosin, cannot recruit septins to the CR. Rather, septin recruitment required the ability of the Anillin C-terminus to bind Rho1-GTP and the presence of the Anillin PH domain, in a sequential mechanism occurring at the plasma membrane, independently of F-actin. Anillin mutations that blocked septin recruitment, but not actomyosin scaffolding, slowed CR closure and disrupted cytokinesis. Thus, CR closure requires coordination of two Rho1-dependent networks: actomyosin and anillo-septin.
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Affiliation(s)
- Sabrya C. Carim
- CHU Sainte-Justine Research Center, 3175 Chemin de la Côte Ste-Catherine, Montréal, QC H3T 1C5, Canada
| | - Gilles R.X. Hickson
- CHU Sainte-Justine Research Center, 3175 Chemin de la Côte Ste-Catherine, Montréal, QC H3T 1C5, Canada
- Département de Pathologie et Biologie Cellulaire, Faculté de Médecine, Université de Montréal, P.O. Box 6128, Station Centre-Ville, Montréal, QC H3C 3J7, Canada
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13
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Güler GÖ, Mostowy S. The septin cytoskeleton: Heteromer composition defines filament function. J Cell Biol 2023; 222:e202302010. [PMID: 36821087 PMCID: PMC9998967 DOI: 10.1083/jcb.202302010] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/24/2023] Open
Abstract
Septins are an evolutionarily conserved protein family whose members form hetero-oligomeric complexes that assemble into filaments and higher-order structures. In this issue, Martins et al. (2022. J. Cell Biol.https://doi.org/10.1083/jcb.202203016) and Cannon et al. (2023. J. Cell Biol.https://doi.org/10.1083/jcb.202204063) report that heteromer composition impacts the physiological role of septin filaments in yeast and human cells.
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Affiliation(s)
- Gizem Özbaykal Güler
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
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14
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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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15
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Grupp B, Gronemeyer T. A biochemical view on the septins, a less known component of the cytoskeleton. Biol Chem 2023; 404:1-13. [PMID: 36423333 DOI: 10.1515/hsz-2022-0263] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 10/30/2022] [Indexed: 11/25/2022]
Abstract
The septins are a conserved family of guanine nucleotide binding proteins, often named the fourth component of the cytoskeleton. They self-assemble into non-polar filaments and further into higher ordered structures. Properly assembled septin structures are required for a wide range of indispensable intracellular processes such as cytokinesis, vesicular transport, polarity establishment and cellular adhesion. Septins belong structurally to the P-Loop NTPases. However, unlike the small GTPases like Ras, septins do not mediate signals to effectors through GTP binding and hydrolysis. The role of nucleotide binding and subsequent GTP hydrolysis by the septins is rather controversially debated. We compile here the structural features from the existing septin crystal- and cryo-EM structures regarding protofilament formation, inter-subunit interface architecture and nucleotide binding and hydrolysis. These findings are supplemented with a summary of available biochemical studies providing information regarding nucleotide binding and hydrolysis of fungal and mammalian septins.
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Affiliation(s)
- Benjamin Grupp
- Institute of Molecular Genetics and Cell Biology, Ulm University, James Franck Ring N27, 89081 Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Ulm University, James Franck Ring N27, 89081 Ulm, Germany
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16
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Benoit B, Poüs C, Baillet A. Septins as membrane influencers: direct play or in association with other cytoskeleton partners. Front Cell Dev Biol 2023; 11:1112319. [PMID: 36875762 PMCID: PMC9982393 DOI: 10.3389/fcell.2023.1112319] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/23/2023] [Indexed: 02/19/2023] Open
Abstract
The cytoskeleton comprises three polymerizing structures that have been studied for a long time, actin microfilaments, microtubules and intermediate filaments, plus more recently investigated dynamic assemblies like septins or the endocytic-sorting complex required for transport (ESCRT) complex. These filament-forming proteins control several cell functions through crosstalks with each other and with membranes. In this review, we report recent works that address how septins bind to membranes, and influence their shaping, organization, properties and functions, either by binding to them directly or indirectly through other cytoskeleton elements.
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Affiliation(s)
- Béatrice Benoit
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
| | - Christian Poüs
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France.,Laboratoire de Biochimie-Hormonologie, Hôpital Antoine Béclère, AP-HP, Hôpitaux Universitaires Paris-Saclay, Clamart, France
| | - Anita Baillet
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
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17
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Septin barriers protect mammalian host cells against Pseudomonas aeruginosa invasion. Cell Rep 2022; 41:111510. [DOI: 10.1016/j.celrep.2022.111510] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2022] [Revised: 04/29/2022] [Accepted: 09/23/2022] [Indexed: 11/24/2022] Open
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18
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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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19
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Gönczi M, Ráduly Z, Szabó L, Fodor J, Telek A, Dobrosi N, Balogh N, Szentesi P, Kis G, Antal M, Trencsenyi G, Dienes B, Csernoch L. Septin7 is indispensable for proper skeletal muscle architecture and function. eLife 2022; 11:e75863. [PMID: 35929607 PMCID: PMC9355566 DOI: 10.7554/elife.75863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2021] [Accepted: 07/03/2022] [Indexed: 11/13/2022] Open
Abstract
Today septins are considered as the fourth component of the cytoskeleton, with the Septin7 isoform playing a critical role in the formation of higher-order structures. While its importance has already been confirmed in several intracellular processes of different organs, very little is known about its role in skeletal muscle. Here, using Septin7 conditional knockdown (KD) mouse model, the C2C12 cell line, and enzymatically isolated adult muscle fibers, the organization and localization of septin filaments are revealed, and an ontogenesis-dependent expression of Septin7 is demonstrated. KD mice displayed a characteristic hunchback phenotype with skeletal deformities, reduction in in vivo and in vitro force generation, and disorganized mitochondrial networks. Furthermore, knockout of Septin7 in C2C12 cells resulted in complete loss of cell division while KD cells provided evidence that Septin7 is essential for proper myotube differentiation. These and the transient increase in Septin7 expression following muscle injury suggest that it may be involved in muscle regeneration and development.
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Affiliation(s)
- Mónika Gönczi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Zsolt Ráduly
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - László Szabó
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - János Fodor
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Andrea Telek
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Nóra Dobrosi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Norbert Balogh
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
- Doctoral School of Molecular Medicine, University of DebrecenDebrecenHungary
| | - Péter Szentesi
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Gréta Kis
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Miklós Antal
- Department of Anatomy, Histology and Embryology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - György Trencsenyi
- Division of Nuclear Medicine and Translational Imaging, Department of Medical Imaging, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - Beatrix Dienes
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
| | - László Csernoch
- Department of Physiology, Faculty of Medicine, University of DebrecenDebrecenHungary
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20
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Zehtabian A, Müller PM, Goisser M, Obendorf L, Jänisch L, Hümpfer N, Rentsch J, Ewers H. Precise measurement of nanoscopic septin ring structures with deep learning-assisted quantitative superresolution microscopy. Mol Biol Cell 2022; 33:ar76. [PMID: 35594179 PMCID: PMC9635280 DOI: 10.1091/mbc.e22-02-0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Abstract
The combination of image analysis and superresolution microscopy methods allows for unprecedented insight into the organization of macromolecular assemblies in cells. Advances in deep learning (DL)-based object recognition enable the automated processing of large amounts of data, resulting in high accuracy through averaging. However, while the analysis of highly symmetric structures of constant size allows for a resolution approaching the dimensions of structural biology, DL-based image recognition may introduce bias. This prohibits the development of readouts for processes that involve significant changes in size or shape of amorphous macromolecular complexes. Here we address this problem by using changes of septin ring structures in single molecule localization-based superresolution microscopy data as a paradigm. We identify potential sources of bias resulting from different training approaches by rigorous testing of trained models using real or simulated data covering a wide range of possible results. In a quantitative comparison of our models, we find that a trade-off exists between measurement accuracy and the range of recognized phenotypes. Using our thus verified models, we find that septin ring size can be explained by the number of subunits they are assembled from alone. Furthermore, we provide a new experimental system for the investigation of septin polymerization.
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Affiliation(s)
- Amin Zehtabian
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Paul Markus Müller
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Maximilian Goisser
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Leon Obendorf
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Lea Jänisch
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Nadja Hümpfer
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Jakob Rentsch
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
| | - Helge Ewers
- Institute for Chemistry and Biochemistry, Freie Universität Berlin, 14195 Berlin, Germany
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21
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Menon MB, Gaestel M. Editorial: Emerging Functions of Septins—Volume II. Front Cell Dev Biol 2022; 10:949824. [PMID: 35784463 PMCID: PMC9246257 DOI: 10.3389/fcell.2022.949824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2022] [Accepted: 05/31/2022] [Indexed: 11/26/2022] Open
Affiliation(s)
- Manoj B. Menon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
- *Correspondence: Manoj B. Menon, ; Matthias Gaestel,
| | - Matthias Gaestel
- Institute for Cell Biochemistry, Hannover Medical School, Hannover, Germany
- *Correspondence: Manoj B. Menon, ; Matthias Gaestel,
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22
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Gargareta VI, Reuschenbach J, Siems SB, Sun T, Piepkorn L, Mangana C, Späte E, Goebbels S, Huitinga I, Möbius W, Nave KA, Jahn O, Werner HB. Conservation and divergence of myelin proteome and oligodendrocyte transcriptome profiles between humans and mice. eLife 2022; 11:77019. [PMID: 35543322 PMCID: PMC9094742 DOI: 10.7554/elife.77019] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/22/2022] [Indexed: 12/12/2022] Open
Abstract
Human myelin disorders are commonly studied in mouse models. Since both clades evolutionarily diverged approximately 85 million years ago, it is critical to know to what extent the myelin protein composition has remained similar. Here, we use quantitative proteomics to analyze myelin purified from human white matter and find that the relative abundance of the structural myelin proteins PLP, MBP, CNP, and SEPTIN8 correlates well with that in C57Bl/6N mice. Conversely, multiple other proteins were identified exclusively or predominantly in human or mouse myelin. This is exemplified by peripheral myelin protein 2 (PMP2), which was specific to human central nervous system myelin, while tetraspanin-2 (TSPAN2) and connexin-29 (CX29/GJC3) were confined to mouse myelin. Assessing published scRNA-seq-datasets, human and mouse oligodendrocytes display well-correlating transcriptome profiles but divergent expression of distinct genes, including Pmp2, Tspan2, and Gjc3. A searchable web interface is accessible via www.mpinat.mpg.de/myelin. Species-dependent diversity of oligodendroglial mRNA expression and myelin protein composition can be informative when translating from mouse models to humans.
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Affiliation(s)
- Vasiliki-Ilya Gargareta
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Josefine Reuschenbach
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sophie B Siems
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Ting Sun
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Lars Piepkorn
- Neuroproteomics Group, Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Translational Neuroproteomics Group, Department of Psychiatry and Psychotherapy, University Medical Center Göttingen, Georg-August-University, Göttingen, Germany
| | - Carolina Mangana
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Erik Späte
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Sandra Goebbels
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Inge Huitinga
- University of Amsterdam, Swammerdam Institute for Life Sciences, Brain Plasticity Group, Amsterdam, Netherlands.,Neuroimmunology Group, Netherlands Institute for Neuroscience, Amsterdam, Netherlands
| | - Wiebke Möbius
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Electron Microscopy Unit, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Klaus-Armin Nave
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
| | - Olaf Jahn
- Neuroproteomics Group, Department of Molecular Neurobiology, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany.,Translational Neuroproteomics Group, Department of Psychiatry and Psychotherapy, University Medical Center Göttingen, Georg-August-University, Göttingen, Germany
| | - Hauke B Werner
- Department of Neurogenetics, Max Planck Institute for Multidisciplinary Sciences, Göttingen, Germany
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23
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Fischer M, Frank D, Rösler R, Johnsson N, Gronemeyer T. Biochemical Characterization of a Human Septin Octamer. Front Cell Dev Biol 2022; 10:771388. [PMID: 35309913 PMCID: PMC8928218 DOI: 10.3389/fcell.2022.771388] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Accepted: 02/14/2022] [Indexed: 11/25/2022] Open
Abstract
Septins are part of the cytoskeleton and polymerize into non-polar filaments of heteromeric hexamers or octamers. They belong to the class of P-loop GTPases but the roles of GTP binding and hydrolysis on filament formation and dynamics are not well understood. The basic human septin building block is the septin rod, a hetero-octamer composed of SEPT2, SEPT6, SEPT7, and SEPT9 with a stoichiometry of 2:2:2:2 (2-6-7-9-9-7-6-2). Septin rods polymerize by end-to-end and lateral joining into linear filaments and higher ordered structures such as rings, sheets, and gauzes. We purified a recombinant human septin octamer from E. coli for in vitro experimentation that is able to polymerize into filaments. We could show that the C-terminal region of the central SEPT9 subunit contributes to filament formation and that the human septin rod decreases the rate of in vitro actin polymerization. We provide further first kinetic data on the nucleotide uptake- and exchange properties of human hexameric and octameric septin rods. We could show that nucleotide uptake prior to hydrolysis is a dynamic process and that a bound nucleotide is exchangeable. However, the hydrolyzed γ-phosphate is not released from the native protein complex. We consequently propose that GTP hydrolysis in human septins does not follow the typical mechanism known from other small GTPases.
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Affiliation(s)
- Martin Fischer
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Dominik Frank
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Reinhild Rösler
- Core Unit Mass Spectrometry and Proteomics, Ulm University, Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
- *Correspondence: Thomas Gronemeyer,
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24
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Microtubule and Actin Cytoskeletal Dynamics in Male Meiotic Cells of Drosophila melanogaster. Cells 2022; 11:cells11040695. [PMID: 35203341 PMCID: PMC8870657 DOI: 10.3390/cells11040695] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2022] [Revised: 02/11/2022] [Accepted: 02/14/2022] [Indexed: 01/12/2023] Open
Abstract
Drosophila dividing spermatocytes offer a highly suitable cell system in which to investigate the coordinated reorganization of microtubule and actin cytoskeleton systems during cell division of animal cells. Like male germ cells of mammals, Drosophila spermatogonia and spermatocytes undergo cleavage furrow ingression during cytokinesis, but abscission does not take place. Thus, clusters of primary and secondary spermatocytes undergo meiotic divisions in synchrony, resulting in cysts of 32 secondary spermatocytes and then 64 spermatids connected by specialized structures called ring canals. The meiotic spindles in Drosophila males are substantially larger than the spindles of mammalian somatic cells and exhibit prominent central spindles and contractile rings during cytokinesis. These characteristics make male meiotic cells particularly amenable to immunofluorescence and live imaging analysis of the spindle microtubules and the actomyosin apparatus during meiotic divisions. Moreover, because the spindle assembly checkpoint is not robust in spermatocytes, Drosophila male meiosis allows investigating of whether gene products required for chromosome segregation play additional roles during cytokinesis. Here, we will review how the research studies on Drosophila male meiotic cells have contributed to our knowledge of the conserved molecular pathways that regulate spindle microtubules and cytokinesis with important implications for the comprehension of cancer and other diseases.
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25
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Shuman B, Momany M. Septins From Protists to People. Front Cell Dev Biol 2022; 9:824850. [PMID: 35111763 PMCID: PMC8801916 DOI: 10.3389/fcell.2021.824850] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/16/2021] [Indexed: 11/13/2022] Open
Abstract
Septin GTPases form nonpolar heteropolymers that play important roles in cytokinesis and other cellular processes. The ability to form heteropolymers appears to be critical to many septin functions and to have been a major driver of the high conservation of many septin domains. Septins fall into five orthologous groups. Members of Groups 1–4 interact with each other to form heterooligomers and are known as the “core septins.” Representative core septins are present in all fungi and animals so far examined and show positional orthology with monomer location in the heteropolymer conserved within groups. In contrast, members of Group 5 are not part of canonical heteropolymers and appear to interact only transiently, if at all, with core septins. Group 5 septins have a spotty distribution, having been identified in specific fungi, ciliates, chlorophyte algae, and brown algae. In this review we compare the septins from nine well-studied model organisms that span the tree of life (Homo sapiens, Drosophila melanogaster, Schistosoma mansoni, Caenorhabditis elegans, Saccharomyces cerevisiae, Aspergillus nidulans, Magnaporthe oryzae, Tetrahymena thermophila, and Chlamydomonas reinhardtii). We focus on classification, evolutionary relationships, conserved motifs, interfaces between monomers, and positional orthology within heteropolymers. Understanding the relationships of septins across kingdoms can give new insight into their functions.
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Dhanya SK, Hasan G. Deficits Associated With Loss of STIM1 in Purkinje Neurons Including Motor Coordination Can Be Rescued by Loss of Septin 7. Front Cell Dev Biol 2021; 9:794807. [PMID: 34993201 PMCID: PMC8724567 DOI: 10.3389/fcell.2021.794807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2021] [Accepted: 11/15/2021] [Indexed: 12/26/2022] Open
Abstract
Septins are cytoskeletal proteins that can assemble to form heteromeric filamentous complexes and regulate a range of membrane-associated cellular functions. SEPT7, a member of the septin family, functions as a negative regulator of the plasma membrane–localized store-operated Ca2+ entry (SOCE) channel, Orai in Drosophila neurons, and in human neural progenitor cells. Knockdown of STIM, a Ca2+ sensor in the endoplasmic reticulum (ER) and an integral component of SOCE, leads to flight deficits in Drosophila that can be rescued by partial loss of SEPT7 in neurons. Here, we tested the effect of reducing and removing SEPT7 in mouse Purkinje neurons (PNs) with the loss of STIM1. Mice with the complete knockout of STIM1 in PNs exhibit several age-dependent changes. These include altered gene expression in PNs, which correlates with increased synapses between climbing fiber (CF) axons and Purkinje neuron (PN) dendrites and a reduced ability to learn a motor coordination task. Removal of either one or two copies of the SEPT7 gene in STIM1KO PNs restored the expression of a subset of genes, including several in the category of neuron projection development. Importantly, the rescue of gene expression in these animals is accompanied by normal CF-PN innervation and an improved ability to learn a motor coordination task in aging mice. Thus, the loss of SEPT7 in PNs further modulates cerebellar circuit function in STIM1KO animals. Our findings are relevant in the context of identifying SEPT7 as a putative therapeutic target for various neurodegenerative diseases caused by reduced intracellular Ca2+ signaling.
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Affiliation(s)
- Sreeja Kumari Dhanya
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
- SASTRA University, Thanjavur, India
| | - Gaiti Hasan
- National Centre for Biological Sciences, Tata Institute of Fundamental Research, Bangalore, India
- *Correspondence: Gaiti Hasan,
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27
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Baillet A, McMurray MA, Oakes PW. Meeting report - the ever-fascinating world of septins. J Cell Sci 2021; 134:jcs259552. [PMID: 34910818 PMCID: PMC10658896 DOI: 10.1242/jcs.259552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Septins are GTP-binding proteins that assemble into hetero-oligomers. They can interact with each other end-to-end to form filaments, making them the fourth element of the cytoskeleton. To update the current knowledge on the ever-increasing implications of these fascinating proteins in cellular functions, a hundred expert scientists from across the globe gathered from 12 to 15 October 2021 in Berlin for the first hybrid-format (on site and virtual) EMBO workshop Molecular and Cell Biology of Septins.
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Affiliation(s)
- Anita Baillet
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, 92290 Châtenay-Malabry, France
| | - Michael A. McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Patrick W. Oakes
- Department of Cell & Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153USA
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28
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Marquardt J, Chen X, Bi E. Septin Assembly and Remodeling at the Cell Division Site During the Cell Cycle. Front Cell Dev Biol 2021; 9:793920. [PMID: 34901034 PMCID: PMC8656427 DOI: 10.3389/fcell.2021.793920] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2021] [Accepted: 11/08/2021] [Indexed: 11/17/2022] Open
Abstract
The septin family of proteins can assemble into filaments that further organize into different higher order structures to perform a variety of different functions in different cell types and organisms. In the budding yeast Saccharomyces cerevisiae, the septins localize to the presumptive bud site as a cortical ring prior to bud emergence, expand into an hourglass at the bud neck (cell division site) during bud growth, and finally “split” into a double ring sandwiching the cell division machinery during cytokinesis. While much work has been done to understand the functions and molecular makeups of these structures, the mechanisms underlying the transitions from one structure to another have largely remained elusive. Recent studies involving advanced imaging and in vitro reconstitution have begun to reveal the vast complexity involved in the regulation of these structural transitions, which defines the focus of discussion in this mini-review.
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Affiliation(s)
- Joseph Marquardt
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Xi Chen
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Erfei Bi
- Department of Cell and Developmental Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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29
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Schuster T, Geiger H. Septins in Stem Cells. Front Cell Dev Biol 2021; 9:801507. [PMID: 34957123 PMCID: PMC8695968 DOI: 10.3389/fcell.2021.801507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/24/2021] [Indexed: 12/01/2022] Open
Abstract
Septins were first described in yeast. Due to extensive research in non-yeast cells, Septins are now recognized across all species as important players in the regulation of the cytoskeleton, in the establishment of polarity, for migration, vesicular trafficking and scaffolding. Stem cells are primarily quiescent cells, and this actively maintained quiescent state is critical for proper stem cell function. Equally important though, stem cells undergo symmetric or asymmetric division, which is likely linked to the level of symmetry found in the mother stem cell. Due to the ability to organize barriers and be able to break symmetry in cells, Septins are thought to have a significant impact on organizing quiescence as well as the mode (symmetric vs asymmetric) of stem cell division to affect self-renewal versus differentiation. Mechanisms of regulating mammalian quiescence and symmetry breaking by Septins are though still somewhat elusive. Within this overview article, we summarize current knowledge on the role of Septins in stem cells ranging from yeast to mice especially with respect to quiescence and asymmetric division, with a special focus on hematopoietic stem cells.
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Affiliation(s)
| | - Hartmut Geiger
- Institute of Molecular Medicine, Ulm University, Ulm, Germany
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30
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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: 34] [Impact Index Per Article: 11.3] [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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31
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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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32
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Mazaheri Moghaddam M, Mazaheri Moghaddam M, Amini M, Bahramzadeh B, Baghbanzadeh A, Biglari A, Sakhinia E. Evaluation of SEPT2 and SEPT4 transcript contents in spermatozoa from men with asthenozoospermia and teratozoospermia. Health Sci Rep 2021; 4:e436. [PMID: 34849407 PMCID: PMC8611181 DOI: 10.1002/hsr2.436] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Revised: 09/24/2021] [Accepted: 10/06/2021] [Indexed: 12/03/2022] Open
Abstract
BACKGROUND AND AIMS Motility and morphological defects of spermatozoa can cause male infertility. Sperm RNAs are related to sperm quality. They are considered to have clinical values as a biomarker for assessing sperm quality and fertility potential. The annulus, located in the mammalian sperm tail, is required for motility and terminal differentiation of the spermatozoa. SEPT2, 4, 6, 7, and 12 proteins are the main components of the annulus in the sperm tail. The study aimed to evaluate SEPT2 and SEPT4 mRNA contents in the spermatozoa of patients with asthenozoospermia and teratozoospermia. METHODS We evaluated transcript levels of SEPT2 and SEPT4 in the sperm samples of 20 asthenozoospermic, 20 teratozoospermic, and 20 normozoospermic samples using quantitative PCR. RESULTS The SEPT2 transcript level was significantly decreased in the asthenozoospermia samples compared with the normal group (P = .013). However, SEPT4 was not significantly different between these two groups. The transcript levels of SEPT2 and SEPT4 were not statistically different between teratozoospermic and normozoospermic groups. CONCLUSION In conclusion, downregulation of SEPT2 in patients with asthenozoospermia appears to be associated with poor sperm motility.
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Affiliation(s)
- Madiheh Mazaheri Moghaddam
- Department of Genetics and Molecular MedicineSchool of Medicine, Zanjan University of Medical Sciences (ZUMS)ZanjanIran
| | | | - Mohammad Amini
- Immunology Research CenterTabriz University of Medical SciencesTabrizIran
| | - Behzad Bahramzadeh
- Al‐Zahra Hospital, Women's Reproductive Health Research CenterTabriz University of Medical SciencesTabrizIran
| | - Amir Baghbanzadeh
- Immunology Research CenterTabriz University of Medical SciencesTabrizIran
| | - Alireza Biglari
- Department of Genetics and Molecular MedicineSchool of Medicine, Zanjan University of Medical Sciences (ZUMS)ZanjanIran
| | - Ebrahim Sakhinia
- Department of Medical Genetics, Faculty of MedicineTabriz University of Medical SciencesTabrizIran
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33
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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: 2] [Impact Index Per Article: 0.7] [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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34
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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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35
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Salameh J, Cantaloube I, Benoit B, Poüs C, Baillet A. Cdc42 and its BORG2 and BORG3 effectors control the subcellular localization of septins between actin stress fibers and microtubules. Curr Biol 2021; 31:4088-4103.e5. [PMID: 34329591 DOI: 10.1016/j.cub.2021.07.004] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 05/28/2021] [Accepted: 07/02/2021] [Indexed: 01/22/2023]
Abstract
Cell resistance to taxanes involves several complementary mechanisms, among which septin relocalization from actin stress fibers to microtubules plays an early role. By investigating the molecular mechanism underlying this relocalization, we found that acute paclitaxel treatment triggers the release from stress fibers and subsequent proteasome-mediated degradation of binder of Rho GTPases 2 (BORG2)/Cdc42 effector protein 3 (Cdc42EP3) and to a lesser extent of BORG3/Cdc42EP5, two Cdc42 effectors that link septins to actin in interphase cells. BORG2 or BORG3 silencing not only caused septin detachment from stress fibers but also mimicked the effects of paclitaxel by triggering both septin relocalization to microtubules and significant drug resistance. Conversely, BORG2 or BORG3 overexpression retained septins on actin fibers even after paclitaxel treatment, without affecting paclitaxel sensitivity. We found that drug-induced inhibition of Cdc42 resulted in a drop in BORG2 level and in the relocalization of septins to microtubules. Accordingly, although septins relocalized when overexpressing an inactive mutant of Cdc42, the expression of a constitutively active mutant acted locally at actin stress fibers to prevent septin release, even after paclitaxel treatment. These findings reveal the role of Cdc42 upstream of BORG2 and BORG3 in controlling the interplay between septins, actin fibers, and microtubules in basal condition and in response to taxanes.
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Affiliation(s)
- Joëlle Salameh
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, Châtenay-Malabry, France
| | - Isabelle Cantaloube
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, Châtenay-Malabry, France
| | - Béatrice Benoit
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, Châtenay-Malabry, France
| | - Christian Poüs
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, Châtenay-Malabry, France; Laboratoire de Biochimie-Hormonologie, Hôpital Antoine Béclère, AP-HP, Clamart, France.
| | - Anita Baillet
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, Châtenay-Malabry, France.
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36
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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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37
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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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38
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Szuba A, Bano F, Castro-Linares G, Iv F, Mavrakis M, Richter RP, Bertin A, Koenderink GH. Membrane binding controls ordered self-assembly of animal septins. eLife 2021; 10:63349. [PMID: 33847563 PMCID: PMC8099429 DOI: 10.7554/elife.63349] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 04/12/2021] [Indexed: 12/23/2022] Open
Abstract
Septins are conserved cytoskeletal proteins that regulate cell cortex mechanics. The mechanisms of their interactions with the plasma membrane remain poorly understood. Here, we show by cell-free reconstitution that binding to flat lipid membranes requires electrostatic interactions of septins with anionic lipids and promotes the ordered self-assembly of fly septins into filamentous meshworks. Transmission electron microscopy reveals that both fly and mammalian septin hexamers form arrays of single and paired filaments. Atomic force microscopy and quartz crystal microbalance demonstrate that the fly filaments form mechanically rigid, 12- to 18-nm thick, double layers of septins. By contrast, C-terminally truncated septin mutants form 4-nm thin monolayers, indicating that stacking requires the C-terminal coiled coils on DSep2 and Pnut subunits. Our work shows that membrane binding is required for fly septins to form ordered arrays of single and paired filaments and provides new insights into the mechanisms by which septins may regulate cell surface mechanics.
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Affiliation(s)
- Agata Szuba
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands
| | - Fouzia Bano
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Gerard Castro-Linares
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
| | - Francois Iv
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Manos Mavrakis
- Institut Fresnel, CNRS, Aix-Marseille Univ, Centrale Marseille, Marseille, France
| | - Ralf P Richter
- School of Biomedical Sciences, Faculty of Biological Sciences, Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, United Kingdom.,School of Physics and Astronomy, Faculty of Engineering and Physical Sciences, University of Leeds, Leeds, United Kingdom.,Bragg Centre for Materials Research, University of Leeds, Leeds, United Kingdom
| | - Aurélie Bertin
- Laboratoire Physico Chimie Curie, Institut Curie, PSL Research University, Paris, France.,Sorbonne Université, Paris, France
| | - Gijsje H Koenderink
- AMOLF, Department of Living Matter, Biological Soft Matter group, Amsterdam, Netherlands.,Department of Bionanoscience, Kavli Institute of Nanoscience Delft, Delft University of Technology, Delft, Netherlands
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39
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Takagi J, Cho C, Duvalyan A, Yan Y, Halloran M, Hanson-Smith V, Thorner J, Finnigan GC. Reconstructed evolutionary history of the yeast septins Cdc11 and Shs1. G3-GENES GENOMES GENETICS 2021; 11:6025175. [PMID: 33561226 PMCID: PMC7849910 DOI: 10.1093/g3journal/jkaa006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/13/2020] [Indexed: 11/21/2022]
Abstract
Septins are GTP-binding proteins conserved across metazoans. They can polymerize into extended filaments and, hence, are considered a component of the cytoskeleton. The number of individual septins varies across the tree of life—yeast (Saccharomyces cerevisiae) has seven distinct subunits, a nematode (Caenorhabditis elegans) has two, and humans have 13. However, the overall geometric unit (an apolar hetero-octameric protomer and filaments assembled there from) has been conserved. To understand septin evolutionary variation, we focused on a related pair of yeast subunits (Cdc11 and Shs1) that appear to have arisen from gene duplication within the fungal clade. Either Cdc11 or Shs1 occupies the terminal position within a hetero-octamer, yet Cdc11 is essential for septin function and cell viability, whereas Shs1 is not. To discern the molecular basis of this divergence, we utilized ancestral gene reconstruction to predict, synthesize, and experimentally examine the most recent common ancestor (“Anc.11-S”) of Cdc11 and Shs1. Anc.11-S was able to occupy the terminal position within an octamer, just like the modern subunits. Although Anc.11-S supplied many of the known functions of Cdc11, it was unable to replace the distinct function(s) of Shs1. To further evaluate the history of Shs1, additional intermediates along a proposed trajectory from Anc.11-S to yeast Shs1 were generated and tested. We demonstrate that multiple events contributed to the current properties of Shs1: (1) loss of Shs1–Shs1 self-association early after duplication, (2) co-evolution of heterotypic Cdc11–Shs1 interaction between neighboring hetero-octamers, and (3) eventual repurposing and acquisition of novel function(s) for its C-terminal extension domain. Thus, a pair of duplicated proteins, despite constraints imposed by assembly into a highly conserved multi-subunit structure, could evolve new functionality via a complex evolutionary pathway.
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Affiliation(s)
- Julie Takagi
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Christina Cho
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Angela Duvalyan
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Yao Yan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Megan Halloran
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
| | - Victor Hanson-Smith
- Department of Microbiology and Immunology, University of California, San Francisco, CA 94158, USA
| | - Jeremy Thorner
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720-3202, USA
| | - Gregory C Finnigan
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, KS 66506, USA
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40
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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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41
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Woods BL, Gladfelter AS. The state of the septin cytoskeleton from assembly to function. Curr Opin Cell Biol 2020; 68:105-112. [PMID: 33188984 DOI: 10.1016/j.ceb.2020.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/01/2020] [Accepted: 10/08/2020] [Indexed: 01/09/2023]
Abstract
Septins are conserved guanine nucleotide-binding proteins that polymerize into filaments at the cell cortex or in association with other cytoskeletal proteins, such as actin or microtubules. As integral players in many morphogenic and signaling events, septins form scaffolds important for the recruitment of the cytokinetic machinery, organization of the plasma membrane, and orientation of cell polarity. Mutations in septins or their misregulation are associated with numerous diseases. Despite growing appreciation for the importance of septins in different aspects of cell biology and disease, septins remain relatively poorly understood compared with other cytoskeletal proteins. Here in this review, we highlight some of the recent developments of the last two years in the field of septin cell biology.
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Affiliation(s)
- Benjamin L Woods
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Amy S Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA; Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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