1
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Mendonça DC, Morais STB, Ciol H, Pinto APA, Leonardo DA, Pereira HD, Valadares NF, Portugal RV, Klaholz BP, Garratt RC, Araujo APU. Structural Insights into Ciona intestinalis Septins: Complexes Suggest a Mechanism for Nucleotide-dependent Interfacial Cross-talk. J Mol Biol 2024; 436:168693. [PMID: 38960133 DOI: 10.1016/j.jmb.2024.168693] [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: 04/28/2024] [Revised: 06/19/2024] [Accepted: 06/27/2024] [Indexed: 07/05/2024]
Abstract
Septins are filamentous nucleotide-binding proteins which can associate with membranes in a curvature-dependent manner leading to structural remodelling and barrier formation. Ciona intestinalis, a model for exploring the development and evolution of the chordate lineage, has only four septin-coding genes within its genome. These represent orthologues of the four classical mammalian subgroups, making it a minimalist non-redundant model for studying the modular assembly of septins into linear oligomers and thereby filamentous polymers. Here, we show that C. intestinalis septins present a similar biochemistry to their human orthologues and also provide the cryo-EM structures of an octamer, a hexamer and a tetrameric sub-complex. The octamer, which has the canonical arrangement (2-6-7-9-9-7-6-2) clearly shows an exposed NC-interface at its termini enabling copolymerization with hexamers into mixed filaments. Indeed, only combinations of septins which had CiSEPT2 occupying the terminal position were able to assemble into filaments via NC-interface association. The CiSEPT7-CiSEPT9 tetramer is the smallest septin particle to be solved by Cryo-EM to date and its good resolution (2.7 Å) provides a well-defined view of the central NC-interface. On the other hand, the CiSEPT7-CiSEPT9 G-interface shows signs of fragility permitting toggling between hexamers and octamers, similar to that seen in human septins but not in yeast. The new structures provide insights concerning the molecular mechanism for cross-talk between adjacent interfaces. This indicates that C. intestinalis may represent a valuable tool for future studies, fulfilling the requirements of a complete but simpler system to understand the mechanisms behind the assembly and dynamics of septin filaments.
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Affiliation(s)
| | | | - Heloísa Ciol
- São Carlos Institute of Physics, USP, São Carlos, SP, Brazil
| | | | | | | | | | - Rodrigo V Portugal
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas, SP, Brazil; Biotechnosciency Program, Federal University of ABC, Santo André, SP, Brazil
| | - Bruno P Klaholz
- Centre for Integrative Biology (CBI), Department of Integrated Structural Biology, IGBMC (Institute of Genetics and of Molecular and Cellular Biology), 67404 Illkirch, France; Centre National de la Recherche Scientifique (CNRS) UMR 7104, 67404 Illkirch, France; Institut National de la Santé et de la Recherche Médicale (INSERM) U964, 67404 Illkirch, France; Université de Strasbourg, 67081 Strasbourg, France
| | | | - Ana P U Araujo
- São Carlos Institute of Physics, USP, São Carlos, SP, Brazil.
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2
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Liu H, Tan R, Tong J, Wen S, Wu C, Rao M, Zhu J, Qi S, Kong E. Palmitoylation is required for Sept8-204 and Sept5 to form vesicle-like structure and colocalize with synaptophysin. J Cell Biochem 2024; 125:e30529. [PMID: 38308620 DOI: 10.1002/jcb.30529] [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: 08/14/2023] [Revised: 01/09/2024] [Accepted: 01/24/2024] [Indexed: 02/05/2024]
Abstract
Sept8 is a vesicle associated protein and there are two typical transcriptional variants (Sept8-204 and Sept8-201) expressed in mice brain. Interestingly, the coexpression of Sept8-204/Sept5 induces the formation of small sized vesicle-like structure, while that of the Sept8-201/Sept5 produces large puncta. Sept8 is previously shown to be palmitoylated. Here it was further revealed that protein palmitoylation is required for Sept8-204/Sept5 to maintain small sized vesicle-like structure and colocalize with synaptophysin, since either the expression of nonpalmitoylated Sept8-204 mutant (Sept8-204-3CA) or inhibiting Sept8-204 palmitoylation by 2-BP with Sept5 produces large puncta, which barely colocalizes with synaptophysin (SYP). Moreover, it was shown that the dynamic palmitoylation of Sept8-204 is controlled by ZDHHC17 and PPT1, loss of ZDHHC17 decreases Sept8-204 palmitoylation and induces large puncta, while loss of PPT1 increases Sept8-204 palmitoylation and induces small sized vesicle-like structure. Together, these findings suggest that palmitoylation is essential for the maintenance of the small sized vesicle-like structure for Sept8-204/Sept5, and may hint their important roles in synaptic functions.
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Affiliation(s)
- Huicong Liu
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Rong Tan
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Jia Tong
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Shuo Wen
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Can Wu
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Muding Rao
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
| | - Jiangli Zhu
- State Key Laboratory of Biotherapy and Cancer Center, Department of Urology, Sichuan University and National Collaborative Innovation Center, Chengdu, China
| | - Shiqian Qi
- State Key Laboratory of Biotherapy and Cancer Center, Department of Urology, Sichuan University and National Collaborative Innovation Center, Chengdu, China
| | - Eryan Kong
- The Second Affiliated Hospital of Xinxiang Medical University, Xinxiang, China
- Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Henan Health Commission Key Laboratory of Gastrointestinal Cancer Prevention and Treatment, Institute of Psychiatry and Neuroscience, Xinxiang Medical University, Xinxiang, China
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3
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Grupp B, Denkhaus L, Gerhardt S, Vögele M, Johnsson N, Gronemeyer T. The structure of a tetrameric septin complex reveals a hydrophobic element essential for NC-interface integrity. Commun Biol 2024; 7:48. [PMID: 38184752 PMCID: PMC10771490 DOI: 10.1038/s42003-023-05734-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2023] [Accepted: 12/20/2023] [Indexed: 01/08/2024] Open
Abstract
The septins of the yeast Saccharomyces cerevisiae assemble into hetero-octameric rods by alternating interactions between neighboring G-domains or N- and C-termini, respectively. These rods polymerize end to end into apolar filaments, forming a ring beneath the prospective new bud that expands during the cell cycle into an hourglass structure. The hourglass finally splits during cytokinesis into a double ring. Understanding these transitions as well as the plasticity of the higher order assemblies requires a detailed knowledge of the underlying structures. Here we present the first X-ray crystal structure of a tetrameric Shs1-Cdc12-Cdc3-Cdc10 complex at a resolution of 3.2 Å. Close inspection of the NC-interfaces of this and other septin structures reveals a conserved contact motif that is essential for NC-interface integrity of yeast and human septins in vivo and in vitro. Using the tetrameric structure in combination with AlphaFold-Multimer allowed us to propose a model of the octameric septin rod.
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Affiliation(s)
- Benjamin Grupp
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Lukas Denkhaus
- Institute of Biochemistry, Albert-Ludwigs University, Freiburg, Germany
| | - Stefan Gerhardt
- Institute of Biochemistry, Albert-Ludwigs University, Freiburg, Germany
| | - Matthis Vögele
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Nils Johnsson
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany
| | - Thomas Gronemeyer
- Institute of Molecular Genetics and Cell Biology, Ulm University, Ulm, Germany.
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4
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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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5
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Chen S, Markovich T, MacKintosh FC. Motor-free contractility of active biopolymer networks. Phys Rev E 2023; 108:044405. [PMID: 37978629 DOI: 10.1103/physreve.108.044405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2023] [Accepted: 09/19/2023] [Indexed: 11/19/2023]
Abstract
Contractility in animal cells is often generated by molecular motors such as myosin, which require polar substrates for their function. Motivated by recent experimental evidence of motor-independent contractility, we propose a robust motor-free mechanism that can generate contraction in biopolymer networks without the need for substrate polarity. We show that contractility is a natural consequence of active binding-unbinding of crosslinkers that breaks the principle of detailed balance, together with the asymmetric force-extension response of semiflexible biopolymers. We have extended our earlier work to discuss the motor-free contraction of viscoelastic biopolymer networks. We calculate the resulting contractile velocity using a microscopic model and show that it can be reduced to a simple coarse-grained model under certain limits. Our model may provide an explanation of recent reports of motor-independent contractility in cells. Our results also suggest a mechanism for generating contractile forces in synthetic active materials.
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Affiliation(s)
- Sihan Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Tomer Markovich
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
- School of Mechanical Engineering, Tel Aviv University, Tel Aviv 69978, Israel
- Center for Physics and Chemistry of Living Systems, Tel Aviv University, Tel Aviv 69978, Israel
| | - Fred C MacKintosh
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
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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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Yu L, Xu L, Chu H, Peng J, Sacharidou A, Hsieh HH, Weinstock A, Khan S, Ma L, Durán JGB, McDonald J, Nelson ER, Park S, McDonnell DP, Moore KJ, Huang LJS, Fisher EA, Mineo C, Huang L, Shaul PW. Macrophage-to-endothelial cell crosstalk by the cholesterol metabolite 27HC promotes atherosclerosis in male mice. Nat Commun 2023; 14:4101. [PMID: 37491347 PMCID: PMC10368733 DOI: 10.1038/s41467-023-39586-z] [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: 04/06/2023] [Accepted: 06/20/2023] [Indexed: 07/27/2023] Open
Abstract
Hypercholesterolemia and vascular inflammation are key interconnected contributors to the pathogenesis of atherosclerosis. How hypercholesterolemia initiates vascular inflammation is poorly understood. Here we show in male mice that hypercholesterolemia-driven endothelial activation, monocyte recruitment and atherosclerotic lesion formation are promoted by a crosstalk between macrophages and endothelial cells mediated by the cholesterol metabolite 27-hydroxycholesterol (27HC). The pro-atherogenic actions of macrophage-derived 27HC require endothelial estrogen receptor alpha (ERα) and disassociation of the cytoplasmic scaffolding protein septin 11 from ERα, leading to extranuclear ERα- and septin 11-dependent activation of NF-κB. Furthermore, pharmacologic inhibition of cyp27a1, which generates 27HC, affords atheroprotection by reducing endothelial activation and monocyte recruitment. These findings demonstrate cell-to-cell communication by 27HC, and identify a major causal linkage between the hypercholesterolemia and vascular inflammation that partner to promote atherosclerosis. Interventions interrupting this linkage may provide the means to blunt vascular inflammation without impairing host defense to combat the risk of atherosclerotic cardiovascular disease that remains despite lipid-lowering therapies.
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Affiliation(s)
- Liming Yu
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Lin Xu
- Quantitative Biomedical Research Center and Peter O'Donnell Jr. School of Public Health, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Haiyan Chu
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Jun Peng
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Anastasia Sacharidou
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Hsi-Hsien Hsieh
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Ada Weinstock
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
- Department of Medicine, University of Chicago School of Medicine, Chicago, IL, 60637, USA
| | - Sohaib Khan
- University of Cincinnati Cancer Center, Cincinnati, OH, 45267, USA
| | - Liqian Ma
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | | | - Jeffrey McDonald
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Erik R Nelson
- Department of Molecular and Integrative Physiology, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Sunghee Park
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Donald P McDonnell
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, 27710, USA
| | - Kathryn J Moore
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Lily Jun-Shen Huang
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Edward A Fisher
- Department of Medicine, New York University School of Medicine, New York, NY, 10016, USA
| | - Chieko Mineo
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Cell Biology, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Linzhang Huang
- State Key Laboratory of Genetic Engineering, Fudan University, Shanghai, 200433, China.
- Shanghai Key Laboratory of Metabolic Remodeling and Health, Fudan University, Shanghai, 200433, China.
- Institute of Metabolism and Integrative Biology, Fudan University, Shanghai, 200433, China.
| | - Philip W Shaul
- Center for Pulmonary and Vascular Biology, Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
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8
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Gorry RL, Brennan K, Lavin PTM, Mazurski T, Mary C, Matallanas D, Guichou JF, Mc Gee MM. Cyclophilin A Isomerisation of Septin 2 Mediates Abscission during Cytokinesis. Int J Mol Sci 2023; 24:11084. [PMID: 37446263 PMCID: PMC10341793 DOI: 10.3390/ijms241311084] [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: 05/15/2023] [Revised: 06/21/2023] [Accepted: 06/24/2023] [Indexed: 07/15/2023] Open
Abstract
The isomerase activity of Cyclophilin A is important for midbody abscission during cell division, however, to date, midbody substrates remain unknown. In this study, we report that the GTP-binding protein Septin 2 interacts with Cyclophilin A. We highlight a dynamic series of Septin 2 phenotypes at the midbody, previously undescribed in human cells. Furthermore, Cyclophilin A depletion or loss of isomerase activity is sufficient to induce phenotypic Septin 2 defects at the midbody. Structural and molecular analysis reveals that Septin 2 proline 259 is important for interaction with Cyclophilin A. Moreover, an isomerisation-deficient EGFP-Septin 2 proline 259 mutant displays defective midbody localisation and undergoes impaired abscission, which is consistent with data from cells with loss of Cyclophilin A expression or activity. Collectively, these data reveal Septin 2 as a novel interacting partner and isomerase substrate of Cyclophilin A at the midbody that is required for abscission during cytokinesis in cancer cells.
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Affiliation(s)
- Rebecca L. Gorry
- School of Biomolecular and Biomedical Science (SBBS), Conway Institute, University College Dublin, D04 V1W8 Dublin, Ireland (K.B.)
| | - Kieran Brennan
- School of Biomolecular and Biomedical Science (SBBS), Conway Institute, University College Dublin, D04 V1W8 Dublin, Ireland (K.B.)
| | - Paul T. M. Lavin
- School of Biomolecular and Biomedical Science (SBBS), Conway Institute, University College Dublin, D04 V1W8 Dublin, Ireland (K.B.)
| | - Tayler Mazurski
- School of Biomolecular and Biomedical Science (SBBS), Conway Institute, University College Dublin, D04 V1W8 Dublin, Ireland (K.B.)
| | - Charline Mary
- Centre de Biologie Structurale, CNRS, INSERM, University Montpellier, 34090 Montpellier, France
| | - David Matallanas
- Systems Biology Ireland (SBI), School of Medicine, University College Dublin, D04 V1W8 Dublin, Ireland
| | - Jean-François Guichou
- Centre de Biologie Structurale, CNRS, INSERM, University Montpellier, 34090 Montpellier, France
| | - Margaret M. Mc Gee
- School of Biomolecular and Biomedical Science (SBBS), Conway Institute, University College Dublin, D04 V1W8 Dublin, Ireland (K.B.)
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9
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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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10
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Benson A, McMurray M. Simultaneous co-overexpression of Saccharomyces cerevisiae septins Cdc3 and Cdc10 drives pervasive, phospholipid-, and tag-dependent plasma membrane localization. Cytoskeleton (Hoboken) 2023; 80:199-214. [PMID: 37098755 PMCID: PMC10524705 DOI: 10.1002/cm.21762] [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: 12/01/2022] [Revised: 03/29/2023] [Accepted: 04/17/2023] [Indexed: 04/27/2023]
Abstract
Septin proteins contribute to many eukaryotic processes involving cellular membranes. In the budding yeast Saccharomyces cerevisiae, septin hetero-oligomers interact with the plasma membrane (PM) almost exclusively at the future site of cytokinesis. While multiple mechanisms of membrane recruitment have been identified, including direct interactions with specific phospholipids and curvature-sensitive interactions via amphipathic helices, these do not fully explain why yeast septins do not localize all over the inner leaflet of the PM. While engineering an inducible split-yellow fluorescent protein (YFP) system to measure the kinetics of yeast septin complex assembly, we found that ectopic co-overexpression of two tagged septins, Cdc3 and Cdc10, resulted in nearly uniform PM localization, as well as perturbation of endogenous septin function. Septin localization and function in gametogenesis were also perturbed. PM localization required the C-terminal YFP fragment fused to the C terminus of Cdc3, the septin-associated kinases Cla4 and Gin4, and phosphotidylinositol-4,5-bis-phosphate (PI[4,5]P2 ), but not the putative PI(4,5)P2 -binding residues in Cdc3. Endogenous Cdc10 was recruited to the PM, likely contributing to the functional interference. PM-localized septins did not exchange with the cytosolic pool, indicative of stable polymers. These findings provide new clues as to what normally restricts septin localization to specific membranes.
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Affiliation(s)
- Aleyna Benson
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
| | - Michael McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, Colorado, USA
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11
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Lee AR, Park CY. Orai1 is an Entotic Ca 2+ Channel for Non-Apoptotic Cell Death, Entosis in Cancer Development. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2205913. [PMID: 36960682 DOI: 10.1002/advs.202205913] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2022] [Revised: 02/16/2023] [Indexed: 05/18/2023]
Abstract
Entosis is a non-apoptotic cell death process that forms characteristic cell-in-cell structures in cancers, killing invading cells. Intracellular Ca2+ dynamics are essential for cellular processes, including actomyosin contractility, migration, and autophagy. However, the significance of Ca2+ and Ca2+ channels participating in entosis is unclear. Here, it is shown that intracellular Ca2+ signaling regulates entosis via SEPTIN-Orai1-Ca2+ /CaM-MLCK-actomyosin axis. Intracellular Ca2+ oscillations in entotic cells show spatiotemporal variations during engulfment, mediated by Orai1 Ca2+ channels in plasma membranes. SEPTIN controlled polarized distribution of Orai1 for local MLCK activation, resulting in MLC phosphorylation and actomyosin contraction, leads to internalization of invasive cells. Ca2+ chelators and SEPTIN, Orai1, and MLCK inhibitors suppress entosis. This study identifies potential targets for treating entosis-associated tumors, showing that Orai1 is an entotic Ca2+ channel that provides essential Ca2+ signaling and sheds light on the molecular mechanism underlying entosis that involves SEPTIN filaments, Orai1, and MLCK.
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Affiliation(s)
- Ah Reum Lee
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
| | - Chan Young Park
- Department of Biological Sciences, Ulsan National Institute of Science and Technology, Ulsan, 44919, Republic of Korea
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12
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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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13
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Ibanes S, El-Alaoui F, Lai-Kee-Him J, Cazevieille C, Hoh F, Lyonnais S, Bron P, Cipelletti L, Picas L, Piatti S. The Syp1/FCHo2 protein induces septin filament bundling through its intrinsically disordered domain. Cell Rep 2022; 41:111765. [PMID: 36476870 DOI: 10.1016/j.celrep.2022.111765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Revised: 09/30/2022] [Accepted: 11/10/2022] [Indexed: 12/12/2022] Open
Abstract
The septin collar of budding yeast is an ordered array of septin filaments that serves a scaffolding function for the cytokinetic machinery at the bud neck and compartmentalizes the membrane between mother and daughter cell. How septin architecture is aided by septin-binding proteins is largely unknown. Syp1 is an endocytic protein that was implicated in the timely recruitment of septins to the newly forming collar through an unknown mechanism. Using advanced microscopy and in vitro reconstitution assays, we show that Syp1 is able to align laterally and tightly pack septin filaments, thereby forming flat bundles or sheets. This property is shared by the Syp1 mammalian counterpart FCHo2, thus emphasizing conserved protein functions. Interestingly, the septin-bundling activity of Syp1 resides mainly in its intrinsically disordered region. Our data uncover the mechanism through which Syp1 promotes septin collar assembly and offer another example of functional diversity of unstructured protein domains.
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Affiliation(s)
- Sandy Ibanes
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier, France
| | - Fatima El-Alaoui
- IRIM (Institut de Recherche en Infectiologie de Montpellier), University of Montpellier, CNRS UMR 9004, 1919 Route de Mende, 34293 Montpellier, France
| | - Joséphine Lai-Kee-Him
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Chantal Cazevieille
- COMET Electron Microscopy Platform, INM (Institute for Neurosciences of Montpellier), University of Montpellier, INSERM U 1298, 80 Rue Augustin Fliche, 34091 Montpellier, France
| | - François Hoh
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Sébastien Lyonnais
- CEMIPAI (Centre d'Etudes des Maladies Infectieuses et Pharmacologie Anti-Infectieuse), University of Montpellier, UAR 3725 CNRS, Montpellier, France
| | - Patrick Bron
- CBS (Centre de Biologie Structurale), University of Montpellier, CNRS UMR 5048, INSERM U 1054, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Luca Cipelletti
- L2C (Laboratoire Charles Coulomb), University of Montpellier, CNRS, Place E. Bataillon, 34095 Montpellier, France; IUF (Institut Universitaire de France), Paris, France
| | - Laura Picas
- IRIM (Institut de Recherche en Infectiologie de Montpellier), University of Montpellier, CNRS UMR 9004, 1919 Route de Mende, 34293 Montpellier, France
| | - Simonetta Piatti
- CRBM (Centre de Recherche en Biologie cellulaire de Montpellier), University of Montpellier, CNRS UMR 5237, 1919 Route de Mende, 34293 Montpellier, France.
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14
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PI(4,5)P2: signaling the plasma membrane. Biochem J 2022; 479:2311-2325. [PMID: 36367756 PMCID: PMC9704524 DOI: 10.1042/bcj20220445] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2022] [Revised: 10/19/2022] [Accepted: 10/21/2022] [Indexed: 11/13/2022]
Abstract
In the almost 70 years since the first hints of its existence, the phosphoinositide, phosphatidyl-D-myo-inositol 4,5-bisphosphate has been found to be central in the biological regulation of plasma membrane (PM) function. Here, we provide an overview of the signaling, transport and structural roles the lipid plays at the cell surface in animal cells. These include being substrate for second messenger generation, direct modulation of receptors, control of membrane traffic, regulation of ion channels and transporters, and modulation of the cytoskeleton and cell polarity. We conclude by re-evaluating PI(4,5)P2's designation as a signaling molecule, instead proposing a cofactor role, enabling PM-selective function for many proteins.
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15
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Mears JA, Ramachandran R. Drp1 and the cytoskeleton: mechanistic nexus in mitochondrial division. CURRENT OPINION IN PHYSIOLOGY 2022; 29:100574. [PMID: 36406887 PMCID: PMC9668076 DOI: 10.1016/j.cophys.2022.100574] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Dynamin-related protein 1 (Drp1), the master regulator of mitochondrial division (MD), interacts with the cytoskeletal elements, namely filamentous actin (F-actin), microtubules (MT), and septins that coincidentally converge at MD sites. However, the mechanistic contributions of these critical elements to, and their cooperativity in, MD remain poorly characterized. Emergent data indicate that the cytoskeleton plays combinatorial modulator, mediator, and effector roles in MD by 'priming' and 'channeling' Drp1 for mechanoenzymatic membrane remodeling. In this brief review, we will outline our current understanding of Drp1-cytoskeleton interactions, focusing on recent progress in the field and a plausible 'diffusion barrier' role for the cytoskeleton in MD.
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Affiliation(s)
- Jason A. Mears
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106
- Center for Mitochondrial Diseases, Case Western Reserve University School of Medicine, Cleveland, OH 44106
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106
| | - Rajesh Ramachandran
- Department of Physiology & Biophysics, Case Western Reserve University School of Medicine, Cleveland, OH 44106
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106
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16
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Kan HW, Ho YC, Chang YS, Hsieh YL. SEPT9 Upregulation in Satellite Glial Cells Associated with Diabetic Polyneuropathy in a Type 2 Diabetes-like Rat Model. Int J Mol Sci 2022; 23:ijms23169372. [PMID: 36012625 PMCID: PMC9409324 DOI: 10.3390/ijms23169372] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Revised: 08/16/2022] [Accepted: 08/18/2022] [Indexed: 11/16/2022] Open
Abstract
Despite the worldwide prevalence and severe complications of type 2 diabetes mellitus (T2DM), the pathophysiological mechanisms underlying the development of diabetic polyneuropathy (DPN) are poorly understood. Beyond strict control of glucose levels, clinical trials for reversing DPN have largely failed. Therefore, understanding the pathophysiological and molecular mechanisms underlying DPN is crucial. Accordingly, this study explored biochemical and neuropathological deficits in a rat model of T2DM induced through high-fat diet (HFD) feeding along with two low-dose streptozotocin (STZ) injections; the deficits were explored through serum lipid, neurobehavioral, neurophysiology, neuropathology, and immunohistochemistry examinations. Our HFD/STZ protocol induced (1) mechanical hyperalgesia and depression-like behaviors, (2) loss of intraepidermal nerve fibers (IENFs) and reduced axonal diameters in sural nerves, and (3) decreased compound muscle action potential. In addition to hyperglycemia, which was correlated with the degree of mechanical hyperalgesia and loss of IENFs, we observed that hypertriglyceridemia was the most dominant deficit in the lipid profiles of the diabetic rats. In particular, SEPT9, the fourth component of the cytoskeleton, increased in the satellite glial cells (SGCs) of the dorsal root ganglia (DRG) in the T2DM-like rats. The number of SEPT9(+) SGCs/DRG was correlated with serum glucose levels and mechanical thresholds. Our findings indicate the putative molecular mechanism underlying DPN, which presumably involves the interaction of SGCs and DRG neurons; nevertheless, further functional research is warranted to clarify the role of SEPT9 in DPN.
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Affiliation(s)
- Hung-Wei Kan
- School of Medicine for International Students, College of Medicine, I-Shou University, Kaohsiung 82445, Taiwan
- Correspondence: (H.-W.K.); (Y.-L.H.); Tel.: +886-7-6151100 (H.-W.K.); +886-7-3121101 (Y.-L.H.)
| | - Yu-Cheng Ho
- School of Medicine, College of Medicine, I-Shou University, Kaohsiung 82445, Taiwan
| | - Ying-Shuang Chang
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
| | - Yu-Lin Hsieh
- Department of Anatomy, School of Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- School of Post-Baccalaureate Medicine, College of Medicine, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
- Department of Medical Research, Kaohsiung Medical University Hospital, Kaohsiung 80708, Taiwan
- Correspondence: (H.-W.K.); (Y.-L.H.); Tel.: +886-7-6151100 (H.-W.K.); +886-7-3121101 (Y.-L.H.)
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17
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Bian C, Su J, Zheng Z, Wei J, Wang H, Meng L, Xin Y, Jiang X. ARTS, an unusual septin, regulates tumorigenesis by promoting apoptosis. Biomed Pharmacother 2022; 152:113281. [PMID: 35714512 DOI: 10.1016/j.biopha.2022.113281] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Revised: 06/04/2022] [Accepted: 06/08/2022] [Indexed: 11/02/2022] Open
Abstract
Apoptosis plays particularly important roles in tumorigenesis through various mechanisms. Apoptosis can be initiated by both extrinsic and intrinsic signals centered in and coming from the mitochondria. Antiapoptotic proteins promote tumor progression, and the occurrence and progression of tumors are closely related to antiapoptotic protein expression. As the only member of the septin gene family with proapoptotic function, apoptosis-related proteins in the TGF-β signaling pathway (ARTS) has received extensive attention for its unique structure. In contrast, unlike other known inhibitors of apoptosis protein (IAP) antagonists, ARTS exhibits a stronger tumor suppressor potential. Recent research has shown that ARTS can bind and inhibit XIAP and Bcl-2 directly or assist p53 in the degradation of Bcl-XL. Here, we review recent advances in the molecular mechanisms by which the proapoptotic protein ARTS, with its unique structure, inhibits tumorigenesis. We also discuss the possibility of mimicking ARTS to develop small-molecule drugs.
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Affiliation(s)
- Chenbin Bian
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
| | - Jing Su
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
| | - Zhuangzhuang Zheng
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
| | - Jinlong Wei
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
| | - Huanhuan Wang
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
| | - Lingbin Meng
- Department of Hematology and Medical Oncology, Moffitt Cancer Center, Tampa, FL 33612, USA.
| | - Ying Xin
- Key Laboratory of Pathobiology, Ministry of Education, Jilin University, Changchun 130021, China.
| | - Xin Jiang
- Jilin Provincial Key Laboratory of Radiation Oncology & Therapy, The First Hospital of Jilin University, Changchun 130021, China; Department of Radiation Oncology, The First Hospital of Jilin University, Changchun 130021, China; NHC Key Laboratory of Radiobiology, School of Public Health, Jilin University, Changchun 130021, China.
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18
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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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19
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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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20
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Kanamaru T, Neuner A, Kurtulmus B, Pereira G. Balancing the length of the distal tip by septins is key for stability and signalling function of primary cilia. EMBO J 2022; 41:e108843. [PMID: 34981518 PMCID: PMC8724769 DOI: 10.15252/embj.2021108843] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 10/19/2021] [Accepted: 10/26/2021] [Indexed: 01/08/2023] Open
Abstract
Primary cilia are antenna-like organelles required for signalling transduction. How cilia structure is mechanistically maintained at steady-state to promote signalling is largely unknown. Here, we define that mammalian primary cilia axonemes are formed by proximal segment (PS) and distal segment (DS) delineated by tubulin polyglutamylation-rich and -poor regions, respectively. The analysis of proximal/distal segmentation indicated that perturbations leading to cilia over-elongation influenced PS or DS length with a different impact on cilia behaviour. We identified septins as novel repressors of DS growth. We show that septins control the localisation of MKS3 and CEP290 required for a functional transition zone (TZ), and the cilia tip accumulation of the microtubule-capping kinesin KIF7, a cilia-growth inhibitor. Live-cell imaging and analysis of sonic-hedgehog (SHH) signalling activation established that DS over-extension increased cilia ectocytosis events and decreased SHH activation. Our data underlines the importance of understanding cilia segmentation for length control and cilia-dependent signalling.
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Affiliation(s)
- Taishi Kanamaru
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Annett Neuner
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Bahtiyar Kurtulmus
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
| | - Gislene Pereira
- Centre for Organismal Studies (COS)University of HeidelbergHeidelbergGermany
- German Cancer Research Centre (DKFZ)DKFZ‐ZMBH AllianceHeidelbergGermany
- Centre for Molecular Biology (ZMBH)University of HeidelbergHeidelbergGermany
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21
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Vickram AS, Anbarasu K, Jeyanthi P, Gulothungan G, Nanmaran R, Thanigaivel S, Sridharan TB, Rohini K. Identification and Structure Prediction of Human Septin-4 as a Biomarker for Diagnosis of Asthenozoospermic Infertile Patients-Critical Finding Toward Personalized Medicine. Front Med (Lausanne) 2021; 8:723019. [PMID: 34926486 PMCID: PMC8677696 DOI: 10.3389/fmed.2021.723019] [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: 06/09/2021] [Accepted: 10/25/2021] [Indexed: 11/22/2022] Open
Abstract
Semen parameters are been found as a key factor to evaluate the count and morphology in the given semen sample. The deep knowledge of male infertility will unravel with semen parameters correlated with molecular and biochemical parameters. The current research study is to identify the motility associated protein and its structure through the in-silico approach. Semen samples were collected and initial analysis including semen parameters was analyzed by using the World Health Organization protocol. Semen biochemical parameters, namely, seminal plasma protein concentration, fructose content, and glucosidase content were calculated and evaluated for correlation. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) were carried out for identification of Septin-4 presence in the semen sample. Mascot search was done for protein conformation and in-silico characterization of Septin-4 by structural modeling in Iterative Threading Assembly Refinement (I-TASSER). Twenty-five nanoseconds molecular dynamics (MD) simulations results showed the stable nature of Septin-4 in the dynamic system. Overall, our results showed the presence of motility-associated protein in normospermia and control samples and not in the case of asthenospermia and oligoasthenospermia. Molecular techniques characterized the presence of Septin-4 and as a novel biomarker for infertility diagnosis.
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Affiliation(s)
- A S Vickram
- Department of Biotechnology, Saveetha School of Engineering (SSE), SIMATS, Chennai, India
| | - K Anbarasu
- Department of Bioinformatics, Saveetha School of Engineering (SSE), SIMATS, Chennai, India
| | - Palanivelu Jeyanthi
- Department of Biotechnology, Vel Tech Rangarajan Dr. Sagunthala R&D Institute of Science and Technology, Chennai, India
| | - G Gulothungan
- Department of Biomedical Engineering, Saveetha School of Engineering (SSE), SIMATS, Chennai, India
| | - R Nanmaran
- Department of Biomedical Engineering, Saveetha School of Engineering (SSE), SIMATS, Chennai, India
| | - S Thanigaivel
- Department of Biotechnology, Saveetha School of Engineering (SSE), SIMATS, Chennai, India
| | - T B Sridharan
- Department of Biotechnology, School of Bio Sciences and Technology, Vellore Institute of Technology (VIT), Vellore, India
| | - Karunakaran Rohini
- Unit of Biochemistry, Faculty of Medicine, AIMST University, Bedong, Malaysia
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22
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Cavini IA, Leonardo DA, Rosa HVD, Castro DKSV, D'Muniz Pereira H, Valadares NF, Araujo APU, Garratt RC. The Structural Biology of Septins and Their Filaments: An Update. Front Cell Dev Biol 2021; 9:765085. [PMID: 34869357 PMCID: PMC8640212 DOI: 10.3389/fcell.2021.765085] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/27/2021] [Indexed: 01/22/2023] Open
Abstract
In order to fully understand any complex biochemical system from a mechanistic point of view, it is necessary to have access to the three-dimensional structures of the molecular components involved. Septins and their oligomers, filaments and higher-order complexes are no exception. Indeed, the spontaneous recruitment of different septin monomers to specific positions along a filament represents a fascinating example of subtle molecular recognition. Over the last few years, the amount of structural information available about these important cytoskeletal proteins has increased dramatically. This has allowed for a more detailed description of their individual domains and the different interfaces formed between them, which are the basis for stabilizing higher-order structures such as hexamers, octamers and fully formed filaments. The flexibility of these structures and the plasticity of the individual interfaces have also begun to be understood. Furthermore, recently, light has been shed on how filaments may bundle into higher-order structures by the formation of antiparallel coiled coils involving the C-terminal domains. Nevertheless, even with these advances, there is still some way to go before we fully understand how the structure and dynamics of septin assemblies are related to their physiological roles, including their interactions with biological membranes and other cytoskeletal components. In this review, we aim to bring together the various strands of structural evidence currently available into a more coherent picture. Although it would be an exaggeration to say that this is complete, recent progress seems to suggest that headway is being made in that direction.
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Affiliation(s)
- Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Higor V D Rosa
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Danielle K S V Castro
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.,São Carlos Institute of Chemistry, University of São Paulo, São Carlos, Brazil
| | | | | | - Ana P U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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23
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Neubauer K, Zieger B. Role of Septins in Endothelial Cells and Platelets. Front Cell Dev Biol 2021; 9:768409. [PMID: 34858990 PMCID: PMC8632023 DOI: 10.3389/fcell.2021.768409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 10/25/2021] [Indexed: 11/13/2022] Open
Abstract
Septins are conserved cytoskeletal GTP-binding proteins identified in almost all eukaryotes except higher plants. Mammalian septins comprise 13 family members with either ubiquitous or organ- and tissue-specific expression patterns. They form filamentous oligomers and complexes with other proteins to serve as diffusions barrier and/or multi-molecular scaffolds to function in a physiologically regulated manner. Diverse septins are highly expressed in endothelial cells and platelets, which play an important role in hemostasis, a process to prevent blood loss after vascular injury. Endothelial septins are involved in cellular processes such as exocytosis and in processes concerning organismal level, like angiogenesis. Septins are additionally found in endothelial cell-cell junctions where their presence is required to maintain the integrity of the barrier function of vascular endothelial monolayers. In platelets, septins are important for activation, degranulation, adhesion, and aggregation. They have been identified as mediators of distinct platelet functions and being essential in primary and secondary hemostatic processes. Septin-knockout mouse studies show the relevance of septins in several aspects of hemostasis. This is in line with reports that dysregulation of septins is clinically relevant in human bleeding disorders. The precise function of septins in the biology of endothelial cells and platelets remains poorly understood. The following mini-review highlights the current knowledge about the role of septin cytoskeleton in regulating critical functions in these two cell types.
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Affiliation(s)
- Katharina Neubauer
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
| | - Barbara Zieger
- Department of Pediatrics and Adolescent Medicine, Division of Pediatric Hematology and Oncology, Medical Center, Faculty of Medicine, University of Freiburg, Freiburg, Germany
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24
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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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25
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Devlin L, Okletey J, Perkins G, Bowen JR, Nakos K, Montagna C, Spiliotis ET. Proteomic profiling of the oncogenic septin 9 reveals isoform-specific interactions in breast cancer cells. Proteomics 2021; 21:e2100155. [PMID: 34409731 DOI: 10.1002/pmic.202100155] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Accepted: 08/05/2021] [Indexed: 02/06/2023]
Abstract
Septins are a family of multimeric GTP-binding proteins, which are abnormally expressed in cancer. Septin 9 (SEPT9) is an essential and ubiquitously expressed septin with multiple isoforms, which have differential expression patterns and effects in breast cancer cells. It is unknown, however, if SEPT9 isoforms associate with different molecular networks and functions. Here, we performed a proteomic screen in MCF-7 breast cancer cells to identify the interactome of GFP-SEPT9 isoforms 1, 4 and 5, which vary significantly in their N-terminal extensions. While all three isoforms associated with SEPT2 and SEPT7, the truncated SEPT9_i4 and SEPT9_i5 interacted with septins of the SEPT6 group more promiscuously than SEPT9_i1, which bound predominately SEPT8. Spatial mapping and functional clustering of non-septin partners showed isoform-specific differences in interactions with proteins of distinct subcellular organelles (e.g., nuclei, centrosomes, cilia) and functions such as cell signalling and ubiquitination. The interactome of the full length SEPT9_i1 was more enriched in cytoskeletal regulators, while the truncated SEPT9_i4 and SEPT9_i5 exhibited preferential and isoform-specific interactions with nuclear, signalling, and ubiquitinating proteins. These data provide evidence for isoform-specific interactions, which arise from truncations in the N-terminal extensions of SEPT9, and point to novel roles in the pathogenesis of breast cancer.
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Affiliation(s)
- Louis Devlin
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA.,Sanofi Pasteur, Swiftwater, Pennsylvania, USA
| | - Joshua Okletey
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | | | - Jonathan R Bowen
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Konstantinos Nakos
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
| | - Cristina Montagna
- Department of Radiology & Oncology, Rutgers Cancer Institute of New Jersey, New Brunswick, New Jersey, USA
| | - Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, Pennsylvania, USA
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26
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Vial A, Taveneau C, Costa L, Chauvin B, Nasrallah H, Godefroy C, Dosset P, Isambert H, Ngo KX, Mangenot S, Levy D, Bertin A, Milhiet PE. Correlative AFM and fluorescence imaging demonstrate nanoscale membrane remodeling and ring-like and tubular structure formation by septins. NANOSCALE 2021; 13:12484-12493. [PMID: 34225356 DOI: 10.1039/d1nr01978c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Septins are ubiquitous cytoskeletal filaments that interact with the inner plasma membrane and are essential for cell division in eukaryotes. In cellular contexts, septins are often localized at micrometric Gaussian curvatures, where they assemble onto ring-like structures. The behavior of budding yeast septins depends on their specific interaction with inositol phospholipids, enriched at the inner leaflet of the plasma membrane. Septin filaments are built from the non-polar self-assembly of short rods into filaments. However, the molecular mechanisms regulating the interplay with the inner plasma membrane and the resulting interaction with specific curvatures are not fully understood. In this report, we have imaged dynamical molecular assemblies of budding yeast septins on PIP2-containing supported lipid bilayers using a combination of high-speed AFM and correlative AFM-fluorescence microscopy. Our results clearly demonstrate that septins are able to bind to flat supported lipid bilayers and thereafter induce the remodeling of membranes. Short septin rods (octamers subunits) can indeed destabilize supported lipid bilayers and reshape the membrane to form 3D structures such as rings and tubes, demonstrating that long filaments are not necessary for septin-induced membrane buckling.
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Affiliation(s)
- Anthony Vial
- Centre de Biochimie Structurale (CBS), Université de Montpellier, CNRS, INSERM, 34090 Montpellier, France.
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27
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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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28
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Spiliotis ET, Kesisova IA. Spatial regulation of microtubule-dependent transport by septin GTPases. Trends Cell Biol 2021; 31:979-993. [PMID: 34253430 DOI: 10.1016/j.tcb.2021.06.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 06/10/2021] [Accepted: 06/14/2021] [Indexed: 01/21/2023]
Abstract
The intracellular long-range transport of membrane vesicles and organelles is mediated by microtubule motors (kinesins, dynein) which move cargo with spatiotemporal accuracy and efficiency. How motors navigate the microtubule network and coordinate their activity on membrane cargo are fundamental but poorly understood questions. New studies show that microtubule-dependent membrane traffic is spatially controlled by septins - a unique family of multimerizing GTPases that associate with microtubules and membrane organelles. We review how septins selectively regulate motor interactions with microtubules and membrane cargo. We posit that septins provide a novel traffic code that specifies the movement and directionality of select motor-cargo complexes on distinct microtubule tracks.
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Affiliation(s)
- Elias T Spiliotis
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA.
| | - Ilona A Kesisova
- Department of Biology, Drexel University, Philadelphia, PA 19104, USA
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29
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Mendonça DC, Guimarães SL, Pereira HD, Pinto AA, de Farias MA, de Godoy AS, Araujo APU, van Heel M, Portugal RV, Garratt RC. An atomic model for the human septin hexamer by cryo-EM. J Mol Biol 2021; 433:167096. [PMID: 34116125 DOI: 10.1016/j.jmb.2021.167096] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 05/25/2021] [Accepted: 06/02/2021] [Indexed: 01/22/2023]
Abstract
In order to form functional filaments, human septins must assemble into hetero-oligomeric rod-like particles which polymerize end-to-end. The rules governing the assembly of these particles and the subsequent filaments are incompletely understood. Although crystallographic approaches have been successful in studying the separate components of the system, there has been difficulty in obtaining high resolution structures of the full particle. Here we report a first cryo-EM structure for a hexameric rod composed of human septins 2, 6 and 7 with a global resolution of ~3.6 Å and a local resolution of between ~3.0 Å and ~5.0 Å. By fitting the previously determined high-resolution crystal structures of the component subunits into the cryo-EM map, we are able to provide an essentially complete model for the particle. This exposes SEPT2 NC-interfaces at the termini of the hexamer and leaves internal cavities between the SEPT6-SEPT7 pairs. The floor of the cavity is formed by the two α0 helices including their polybasic regions. These are locked into place between the two subunits by interactions made with the α5 and α6 helices of the neighbouring monomer together with its polyacidic region. The cavity may serve to provide space allowing the subunits to move with respect to one another. The elongated particle shows a tendency to bend at its centre where two copies of SEPT7 form a homodimeric G-interface. Such bending is almost certainly related to the ability of septin filaments to recognize and even induce membrane curvature.
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Affiliation(s)
| | | | | | | | | | | | - Ana P U Araujo
- São Carlos Institute of Physics, USP, São Carlos, SP, Brazil
| | - Marin van Heel
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas, SP, Brazil
| | - Rodrigo V Portugal
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas, SP, Brazil.
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30
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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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31
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Kutsch M, González-Prieto C, Lesser CF, Coers J. The GBP1 microcapsule interferes with IcsA-dependent septin cage assembly around Shigella flexneri. Pathog Dis 2021; 79:6246431. [PMID: 33885766 DOI: 10.1093/femspd/ftab023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 04/08/2021] [Indexed: 12/20/2022] Open
Abstract
Many cytosolic bacterial pathogens hijack the host actin polymerization machinery to form actin tails that promote direct cell-to-cell spread, enabling these pathogens to avoid extracellular immune defenses. However, these pathogens are still susceptible to intracellular cell-autonomous immune responses that restrict bacterial actin-based motility. Two classes of cytosolic antimotility factors, septins and guanylate-binding proteins (GBPs), have recently been established to block actin tail formation by the human-adapted bacterial pathogen Shigella flexneri. Both septin cages and GBP1 microcapsules restrict S. flexneri cell-to-cell spread by blocking S. flexneri actin-based motility. While septins assemble into cage-like structures around immobile S. flexneri, GBP1 forms microcapsules around both motile and immobile bacteria. The interplay between these two defense programs remains elusive. Here, we demonstrate that GBP1 microcapsules block septin cage assembly, likely by interfering with the function of S. flexneri IcsA, the outer membrane protein that promotes actin-based motility, as this protein is required for septin cage formation. However, S. flexneri that escape from GBP1 microcapsules via the activity of IpaH9.8, a type III secreted effector that promotes the degradation of GBPs, are often captured within septin cages. Thus, our studies reveal how septin cages and GBP1 microcapsules represent complementary host cell antimotility strategies.
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Affiliation(s)
- Miriam Kutsch
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Coral González-Prieto
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02115, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Cammie F Lesser
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02115, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jörn Coers
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.,Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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32
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Mela A, Momany M. Septins coordinate cell wall integrity and lipid metabolism in a sphingolipid-dependent process. J Cell Sci 2021; 135:256543. [PMID: 33912961 DOI: 10.1242/jcs.258336] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 12/31/2020] [Indexed: 01/09/2023] Open
Abstract
Septins colocalize with membrane sterol-rich regions and facilitate recruitment of cell wall synthases during wall remodeling. We show that null mutants missing an Aspergillus nidulans core septin present in hexamers and octamers (ΔaspAcdc11, ΔaspBcdc3 or ΔaspCcdc12) are sensitive to multiple cell wall-disturbing agents that activate the cell wall integrity MAPK pathway. The null mutant missing the octamer-exclusive core septin (ΔaspDcdc10) showed similar sensitivity, but only to a single cell wall-disturbing agent and the null mutant missing the noncore septin (ΔaspE) showed only very mild sensitivity to a different single agent. Core septin mutants showed changes in wall polysaccharide composition and chitin synthase localization. Mutants missing any of the five septins resisted ergosterol-disrupting agents. Hexamer mutants showed increased sensitivity to sphingolipid-disrupting agents. Core septins mislocalized after treatment with sphingolipid-disrupting agents, but not after ergosterol-disrupting agents. Our data suggest that the core septins are involved in cell wall integrity signaling, that all five septins are involved in monitoring ergosterol metabolism, that the hexamer septins are required for sphingolipid metabolism and that septins require sphingolipids to coordinate the cell wall integrity response.
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Affiliation(s)
- Alexander Mela
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, 2502 Miller Plant Science Building, Athens, GA 30602, USA
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33
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Septins in Infections: Focus on Viruses. Pathogens 2021; 10:pathogens10030278. [PMID: 33801245 PMCID: PMC8001386 DOI: 10.3390/pathogens10030278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2021] [Revised: 02/17/2021] [Accepted: 02/25/2021] [Indexed: 11/17/2022] Open
Abstract
Human septins comprise a family of 13 genes that encode conserved GTP-binding proteins. They form nonpolar complexes, which assemble into higher-order structures, such as bundles, scaffolding structures, or rings. Septins are counted among the cytoskeletal elements. They interact with the actin and microtubule networks and can bind to membranes. Many cellular functions with septin participation have been described in the literature, including cytokinesis, motility, forming of scaffolding platforms or lateral diffusion barriers, vesicle transport, exocytosis, and recognition of micron-scale curvature. Septin dysfunction has been implicated in diverse human pathologies, including neurodegeneration and tumorigenesis. Moreover, septins are thought to affect the outcome of host–microbe interactions. Implication of septins has been demonstrated in fungal, bacterial, and viral infections. Knowledge on the precise function of a particular septin in the different steps of the virus infection and replication cycle is still limited. Published data for vaccinia virus (VACV), hepatitis C virus (HCV), influenza A virus (H1N1 and H5N1), human herpesvirus 8 (HHV-8), and Zika virus (ZIKV), all of major concern for public health, will be discussed here.
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34
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Kakebeen AD, Huebner RJ, Shindo A, Kwon K, Kwon T, Wills AE, Wallingford JB. A temporally resolved transcriptome for developing "Keller" explants of the Xenopus laevis dorsal marginal zone. Dev Dyn 2021; 250:717-731. [PMID: 33368695 DOI: 10.1002/dvdy.289] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/20/2020] [Accepted: 11/30/2020] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Explanted tissues from vertebrate embryos reliably develop in culture and have provided essential paradigms for understanding embryogenesis, from early embryological investigations of induction, to the extensive study of Xenopus animal caps, to the current studies of mammalian gastruloids. Cultured explants of the Xenopus dorsal marginal zone ("Keller" explants) serve as a central paradigm for studies of convergent extension cell movements, yet we know little about the global patterns of gene expression in these explants. RESULTS In an effort to more thoroughly develop this important model system, we provide here a time-resolved bulk transcriptome for developing Keller explants. CONCLUSIONS The dataset reported here provides a useful resource for those using Keller explants for studies of morphogenesis and provide genome-scale insights into the temporal patterns of gene expression in an important tissue when explanted and grown in culture.
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Affiliation(s)
- Anneke D Kakebeen
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - Robert J Huebner
- Department of Molecular Biosciences, University of Texas, Austin, Texas, USA
| | - Asako Shindo
- Division of Biological Science, Nagoya University, Nagoya, Japan
| | - Kujin Kwon
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, (UNIST), Ulsan, Republic of Korea
| | - Taejoon Kwon
- Department of Biomedical Engineering, Ulsan National Institute of Science and Technology, (UNIST), Ulsan, Republic of Korea.,Center for Genomic Integrity, Institute for Basic Science (IBS), Ulsan, Republic of Korea
| | - Andrea E Wills
- Department of Biochemistry, University of Washington, Seattle, Washington, USA
| | - John B Wallingford
- Department of Molecular Biosciences, University of Texas, Austin, Texas, USA
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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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36
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Kim J, Cooper JA. Junctional Localization of Septin 2 Is Required for Organization of Junctional Proteins in Static Endothelial Monolayers. Arterioscler Thromb Vasc Biol 2021; 41:346-359. [PMID: 33147991 PMCID: PMC7769918 DOI: 10.1161/atvbaha.120.315472] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
OBJECTIVE Septin 2 is localized at junctions in human microvascular endothelial monolayers. The junctional localization of septin 2 is necessary for organization of cell-cell adhesion proteins of endothelial cells. Approach and Results: Septin 2 was depleted at junctions by suppression of expression using shRNA, treatment with inflammatory cytokine, TNF (tumor necrosis factor)-α, and ectopic overexpression of septin 2 phosphatidylinositol 4,5-bisphosphate binding mutant defect in interaction with plasma membrane. Under those conditions, organizations and expression levels of various junctional proteins were analyzed. Confocal images of immunofluorescence staining showed substantial disorganization of adherens junctional proteins, nectin-2 and afadin, TJP (tight junction protein), ZO (zonula occludens)-1, and intercellular adhesion protein, PECAM-1 (platelet-endothelial cell adhesion molecule-1). Immunoblots for those proteins did not show significant changes in expression except for nectin-2 that highly increased in expression. Significant differential gene expression profiles and biological pathway analysis by septin 2 suppression and by TNF-α treatment using RNA-seq showed common overlapping pathways. The commonalities in expression may be consistent with the similar effects on the overall organization of cell-cell adhesion proteins. CONCLUSIONS Localization of septin 2 at cell junctions are required for the arrangement of junctional proteins and the integrity of the barrier formed by endothelial monolayers.
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Affiliation(s)
- Joanna Kim
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
| | - John A. Cooper
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, Saint Louis, MO, USA
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37
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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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38
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Chen S, Markovich T, MacKintosh FC. Motor-Free Contractility in Active Gels. PHYSICAL REVIEW LETTERS 2020; 125:208101. [PMID: 33258614 DOI: 10.1103/physrevlett.125.208101] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 10/23/2020] [Indexed: 06/12/2023]
Abstract
Animal cells form contractile structures to promote various functions, from cell motility to cell division. Force generation in these structures is often due to molecular motors such as myosin that require polar substrates for their function. Here, we propose a motor-free mechanism that can generate contraction in biopolymer networks without the need for polarity. This mechanism is based on active binding and unbinding of cross-linkers that breaks the principle of detailed balance, together with the asymmetric force-extension response of semiflexible biopolymers. We find that these two ingredients can generate steady state contraction via a nonthermal, ratchetlike process. We calculate the resulting force-velocity relation using both coarse-grained and microscopic models.
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Affiliation(s)
- Sihan Chen
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Tomer Markovich
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
| | - Fred C MacKintosh
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Center for Theoretical Biological Physics, Rice University, Houston, Texas 77005, USA
- Department of Chemical and Biomolecular Engineering, Rice University, Houston, Texas 77005, USA
- Department of Chemistry, Rice University, Houston, Texas 77005, USA
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39
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Novel Functions of the Septin Cytoskeleton: Shaping Up Tissue Inflammation and Fibrosis. THE AMERICAN JOURNAL OF PATHOLOGY 2020; 191:40-51. [PMID: 33039354 DOI: 10.1016/j.ajpath.2020.09.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Revised: 08/24/2020] [Accepted: 09/16/2020] [Indexed: 12/19/2022]
Abstract
Chronic inflammatory diseases cause profound alterations in tissue homeostasis, including unchecked activation of immune and nonimmune cells leading to disease complications such as aberrant tissue repair and fibrosis. Current anti-inflammatory therapies are often insufficient in preventing or reversing these complications. Remodeling of the intracellular cytoskeleton is critical for cell activation in inflamed and fibrotic tissues; however, the cytoskeleton has not been adequately explored as a therapeutic target in inflammation. Septins are GTP-binding proteins that self-assemble into higher order cytoskeletal structures. The septin cytoskeleton exhibits a number of critical cellular functions, including regulation of cell shape and polarity, cytokinesis, cell migration, vesicle trafficking, and receptor signaling. Surprisingly, little is known about the role of the septin cytoskeleton in inflammation. This article reviews emerging evidence implicating different septins in the regulation of host-pathogen interactions, immune cell functions, and tissue fibrosis. Targeting of the septin cytoskeleton as a potential future therapeutic intervention in human inflammatory and fibrotic diseases is also discussed.
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40
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Wang L, Yan M, Wu S, Mao B, Wong CKC, Ge R, Sun F, Cheng CY. Microtubule Cytoskeleton and Spermatogenesis-Lesson From Studies of Toxicant Models. Toxicol Sci 2020; 177:305-315. [PMID: 32647867 PMCID: PMC7548287 DOI: 10.1093/toxsci/kfaa109] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
Studies have shown that mammalian testes, in particular the Sertoli cells, are highly susceptible to exposure of environmental toxicants, such as cadmium, perfluorooctanesulfonate, phthalates, 2,5-hexanedione and bisphenol A. However, important studies conducted by reproductive toxicologists and/or biologists in the past have been treated as toxicology reports per se. Yet, many of these studies provided important mechanistic insights on the toxicant-induced testis injury and reproductive dysfunction, relevant to the biology of the testis and spermatogenesis. Furthermore, recent studies have shown that findings obtained from toxicant models are exceedingly helpful tools to unravel the biology of testis function in particular spermatogenesis, including specific cellular events associated with spermatid transport to support spermiogenesis and spermiation. In this review, we critically evaluate some recent data, focusing primarily on the molecular structure and role of microtubules in cellular function, illustrating the importance of toxicant models to unravel the biology of microtubule cytoskeleton in supporting spermatogenesis, well beyond information on toxicology. These findings have opened up some potential areas of research which should be carefully evaluated in the years to come.
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Affiliation(s)
- Lingling Wang
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Ming Yan
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Siwen Wu
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Baiping Mao
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Jiangsu Key Laboratory of Drug Screening, China Pharmaceutical University, Nanjing, Jiangsu 210009, China
| | - Chris K C Wong
- Department of Biology, Croucher Institute for Environmental Sciences, Hong Kong Baptist University, Kowloon, Hong Kong, China
| | - Renshan Ge
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
| | - Fei Sun
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, Jiangsu 226001, China
| | - C Yan Cheng
- The Second Affiliated Hospital and Yuying Children’s Hospital, Wenzhou Medical University, Wenzhou, Zhejiang 325027, China
- The Mary M. Wohlford Laboratory for Male Contraceptive Research, Center for Biomedical Research, Population Council, New York, New York 10065
- Institute of Reproductive Medicine, Nantong University School of Medicine, Nantong, Jiangsu 226001, China
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41
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Rosa HVD, Leonardo DA, Brognara G, Brandão-Neto J, D'Muniz Pereira H, Araújo APU, Garratt RC. Molecular Recognition at Septin Interfaces: The Switches Hold the Key. J Mol Biol 2020; 432:5784-5801. [DOI: 10.1016/j.jmb.2020.09.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2020] [Revised: 08/25/2020] [Accepted: 09/01/2020] [Indexed: 01/22/2023]
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42
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Blangy A, Bompard G, Guerit D, Marie P, Maurin J, Morel A, Vives V. The osteoclast cytoskeleton - current understanding and therapeutic perspectives for osteoporosis. J Cell Sci 2020; 133:133/13/jcs244798. [PMID: 32611680 DOI: 10.1242/jcs.244798] [Citation(s) in RCA: 37] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Osteoclasts are giant multinucleated myeloid cells specialized for bone resorption, which is essential for the preservation of bone health throughout life. The activity of osteoclasts relies on the typical organization of osteoclast cytoskeleton components into a highly complex structure comprising actin, microtubules and other cytoskeletal proteins that constitutes the backbone of the bone resorption apparatus. The development of methods to differentiate osteoclasts in culture and manipulate them genetically, as well as improvements in cell imaging technologies, has shed light onto the molecular mechanisms that control the structure and dynamics of the osteoclast cytoskeleton, and thus the mechanism of bone resorption. Although essential for normal bone physiology, abnormal osteoclast activity can cause bone defects, in particular their hyper-activation is commonly associated with many pathologies, hormonal imbalance and medical treatments. Increased bone degradation by osteoclasts provokes progressive bone loss, leading to osteoporosis, with the resulting bone frailty leading to fractures, loss of autonomy and premature death. In this context, the osteoclast cytoskeleton has recently proven to be a relevant therapeutic target for controlling pathological bone resorption levels. Here, we review the present knowledge on the regulatory mechanisms of the osteoclast cytoskeleton that control their bone resorption activity in normal and pathological conditions.
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Affiliation(s)
- Anne Blangy
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - Guillaume Bompard
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - David Guerit
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - Pauline Marie
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - Justine Maurin
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - Anne Morel
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
| | - Virginie Vives
- Centre de Recherche de Biologie Cellulaire de Montpellier (CRBM), Montpellier Univ., CNRS, 34000 Montpellier, France
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43
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Castro DKSDV, da Silva SMDO, Pereira HD, Macedo JNA, Leonardo DA, Valadares NF, Kumagai PS, Brandão-Neto J, Araújo APU, Garratt RC. A complete compendium of crystal structures for the human SEPT3 subgroup reveals functional plasticity at a specific septin interface. IUCRJ 2020; 7:462-479. [PMID: 32431830 PMCID: PMC7201284 DOI: 10.1107/s2052252520002973] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/03/2020] [Indexed: 06/11/2023]
Abstract
Human septins 3, 9 and 12 are the only members of a specific subgroup of septins that display several unusual features, including the absence of a C-terminal coiled coil. This particular subgroup (the SEPT3 septins) are present in rod-like octameric protofilaments but are lacking in similar hexameric assemblies, which only contain representatives of the three remaining subgroups. Both hexamers and octamers can self-assemble into mixed filaments by end-to-end association, implying that the SEPT3 septins may facilitate polymerization but not necessarily function. These filaments frequently associate into higher order complexes which associate with biological membranes, triggering a wide range of cellular events. In the present work, a complete compendium of crystal structures for the GTP-binding domains of all of the SEPT3 subgroup members when bound to either GDP or to a GTP analogue is provided. The structures reveal a unique degree of plasticity at one of the filamentous interfaces (dubbed NC). Specifically, structures of the GDP and GTPγS complexes of SEPT9 reveal a squeezing mechanism at the NC interface which would expel a polybasic region from its binding site and render it free to interact with negatively charged membranes. On the other hand, a polyacidic region associated with helix α5', the orientation of which is particular to this subgroup, provides a safe haven for the polybasic region when retracted within the interface. Together, these results suggest a mechanism which couples GTP binding and hydrolysis to membrane association and implies a unique role for the SEPT3 subgroup in this process. These observations can be accounted for by constellations of specific amino-acid residues that are found only in this subgroup and by the absence of the C-terminal coiled coil. Such conclusions can only be reached owing to the completeness of the structural studies presented here.
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Affiliation(s)
- Danielle Karoline Silva do Vale Castro
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, São Carlos-SP 13566-590, Brazil
| | - Sabrina Matos de Oliveira da Silva
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Instituto de Química de São Carlos, Universidade de São Paulo, Avenida Trabalhador São-carlense 400, São Carlos-SP 13566-590, Brazil
| | - Humberto D’Muniz Pereira
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Joci Neuby Alves Macedo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
- Federal Institute of Education, Science and Technology of Rondonia, Rodovia BR-174, Km 3, Vilhena-RO 76980-000, Brazil
| | - Diego Antonio Leonardo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Napoleão Fonseca Valadares
- Departamento de Biologia Celular, Universidade de Brasília, Instituto de Ciências Biológicas, Brasília-DF 70910900, Brazil
| | - Patricia Suemy Kumagai
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - José Brandão-Neto
- Diamond Light Source, Diamond House, Harwell Science and Innovation Campus, Didcot OX11 0DE, United Kingdom
| | - Ana Paula Ulian Araújo
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
| | - Richard Charles Garratt
- Instituto de Física de São Carlos, Universidade de São Paulo, Avenida Joao Dagnone 1100, São Carlos-SP 13563-723, Brazil
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Mendonça DC, Macedo JN, Guimarães SL, Barroso da Silva FL, Cassago A, Garratt RC, Portugal RV, Araujo APU. A revised order of subunits in mammalian septin complexes. Cytoskeleton (Hoboken) 2019; 76:457-466. [PMID: 31608568 DOI: 10.1002/cm.21569] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2019] [Revised: 09/18/2019] [Accepted: 09/19/2019] [Indexed: 12/15/2022]
Abstract
Septins are GTP binding proteins considered to be novel components of the cytoskeleton. They polymerize into filaments based on hexameric or octameric core particles in which two copies of either three or four different septins, respectively, assemble into a specific sequence. Viable combinations of the 13 human septins are believed to obey substitution rules in which the different septins involved must come from distinct subgroups. The hexameric assembly, for example, has been reported to be SEPT7-SEPT6-SEPT2-SEPT2-SEPT6-SEPT7. Here, we have replaced SEPT2 by SEPT5 according to the substitution rules and used transmission electron microscopy to demonstrate that the resulting recombinant complex assembles into hexameric particles which are inverted with respect that predicted previously. MBP-SEPT5 constructs and immunostaining show that SEPT5 occupies the terminal positions of the hexamer. We further show that this is also true for the assembly including SEPT2, in direct contradiction with that reported previously. Consequently, both complexes expose an NC interface, as reported for yeast, which we show to be more susceptible to high salt concentrations. The correct assembly for the canonical combination of septins 2-6-7 is therefore established to be SEPT2-SEPT6-SEPT7-SEPT7-SEPT6-SEPT2, implying the need for revision of the mechanisms involved in filament assembly.
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Affiliation(s)
| | - Joci N Macedo
- São Carlos Institute of Physics, USP, São Carlos, SP, Brazil
- Federal Institute of Education, Science and Technology of Rondonia
| | | | - Fernando L Barroso da Silva
- Faculty of Pharmaceutical Sciences, USP, Ribeirão Preto, SP, Brazil
- UMR_S 1134, Université Paris Diderot, Paris, France
| | - Alexandre Cassago
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas, SP, Brazil
| | | | - Rodrigo V Portugal
- Brazilian Nanotechnology National Laboratory, CNPEM, Campinas, SP, Brazil
| | - Ana P U Araujo
- São Carlos Institute of Physics, USP, São Carlos, SP, Brazil
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45
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Kumagai PS, Martins CS, Sales EM, Rosa HV, Mendonça DC, Damalio JCP, Spinozzi F, Itri R, Araujo APU. Correct partner makes the difference: Septin G-interface plays a critical role in amyloid formation. Int J Biol Macromol 2019; 133:428-435. [DOI: 10.1016/j.ijbiomac.2019.04.105] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Revised: 04/12/2019] [Accepted: 04/15/2019] [Indexed: 01/04/2023]
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46
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A blueprint of septin expression in human tissues. Funct Integr Genomics 2019; 19:787-797. [PMID: 31089837 DOI: 10.1007/s10142-019-00690-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 05/03/2019] [Accepted: 05/06/2019] [Indexed: 12/29/2022]
Abstract
Septins are GTP-binding proteins that polymerize to form filaments involved in several important biological processes. In human, 13 distinct septins genes are classified in four groups. Filaments formed by septins are complex and usually involve members of each group in specific positions. Expression data from GTEx database, a publicly available expression database with thousands of samples derived from multiple human tissues, was used to evaluate the expression of septins. The brain is noticeably a hotspot for septin expression where few genes contribute to a large portion of septin transcript pool. Co-expression data between septins suggests two predominant specific complexes in brain tissues and one filament in other tissues. SEPT3 and SEPT5 are two genes highly expressed in the brain and with a strong co-expression in all brain tissues. Additional analysis shows that the expression of these two genes is highly variable between individuals, but significantly dependent on the individual's age. Age-dependent decrease of expression from those two septins involved in synapses reinforces their possible link with cognitive decay and neurodegenerative diseases associated with aging. Analysis of enrichment of Gene Ontology terms from lists of genes consistently co-expressed with septins suggests participation in diverse biological processes, pointing out some novel roles for septins. Interestingly, we observed strong consistency of some of these terms with experimentally described roles of septins. Coordination of septins expression with genes involved in DNA repair and cell cycle control may provide insights for previously described links between septins and cancer.
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47
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Brognara G, Pereira HDM, Brandão-Neto J, Araujo APU, Garratt RC. Revisiting SEPT7 and the slippage of β-strands in the septin family. J Struct Biol 2019; 207:67-73. [PMID: 31009756 DOI: 10.1016/j.jsb.2019.04.015] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2019] [Revised: 04/17/2019] [Accepted: 04/18/2019] [Indexed: 12/12/2022]
Abstract
Septins are GTP-binding proteins that will often spontaneously assemble into filaments. In some species, particularly budding yeast, it is well known that these are capable of associating with membranes in order to fulfill their cellular role as a component of the cytoskeleton. Different from other human septins, SEPT7 appears to be unique in that it is an essential component of all hetero-oligomeric complexes described to date. As a step towards understanding the molecular basis of filament assembly, here we present two high-resolution structures of the SEPT7 GTPase domain complexed with GDP. One of these reveals a previously unreported coordination for the magnesium ion involving four water molecules and only a tenuous connection to the protein. The higher resolution structures provide unambiguous insight into the interactions at the G-interface where a structural motif based on an antiparallel β-bridge allows for the rationalization of why some septins show nucleotide-dependent β-strand slippage and others do not.
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Affiliation(s)
- Gabriel Brognara
- São Carlos Institute of Physics, University of São Paulo, São Carlos, São Paulo, Brazil
| | | | - José Brandão-Neto
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire, United Kingdom
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Auxier B, Dee J, Berbee ML, Momany M. Diversity of opisthokont septin proteins reveals structural constraints and conserved motifs. BMC Evol Biol 2019; 19:4. [PMID: 30616529 PMCID: PMC6323724 DOI: 10.1186/s12862-018-1297-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2018] [Accepted: 11/19/2018] [Indexed: 01/22/2023] Open
Abstract
BACKGROUND Septins are cytoskeletal proteins important in cell division and in establishing and maintaining cell polarity. Although septins are found in various eukaryotes, septin genes had the richest history of duplication and diversification in the animals, fungi and protists that comprise opisthokonts. Opisthokont septin paralogs encode modular proteins that assemble into heteropolymeric higher order structures. The heteropolymers can create physical barriers to diffusion or serve as scaffolds organizing other morphogenetic proteins. How the paralogous septin modules interact to form heteropolymers is still unclear. Through comparative analyses, we hoped to clarify the evolutionary origin of septin diversity and to suggest which amino acid residues were responsible for subunit binding specificity. RESULTS Here we take advantage of newly sequenced genomes to reconcile septin gene trees with a species phylogeny from 22 animals, fungi and protists. Our phylogenetic analysis divided 120 septins representing the 22 taxa into seven clades (Groups) of paralogs. Suggesting that septin genes duplicated early in opisthokont evolution, animal and fungal lineages share septin Groups 1A, 4 and possibly also 1B and 2. Group 5 septins were present in fungi but not in animals and whether they were present in the opisthokont ancestor was unclear. Protein homology folding showed that previously identified conserved septin motifs were all located near interface regions between the adjacent septin monomers. We found specific interface residues associated with each septin Group that are candidates for providing subunit binding specificity. CONCLUSIONS This work reveals that duplication of septin genes began in an ancestral opisthokont more than a billion years ago and continued through the diversification of animals and fungi. Evidence for evolutionary conservation of ~ 49 interface residues will inform mutagenesis experiments and lead to improved understanding of the rules guiding septin heteropolymer formation and from there, to improved understanding of development of form in animals and fungi.
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Affiliation(s)
- Benjamin Auxier
- Department of Botany, University of British Columbia, Vancouver, Canada
- current address: Laboratory of Genetics, Wageningen University and Research, P.O. Box 16, 6700AA, Wageningen, The Netherlands
| | - Jaclyn Dee
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Mary L. Berbee
- Department of Botany, University of British Columbia, Vancouver, Canada
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, USA
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NISHIMURA Y, KASAHARA K, INAGAKI M. Intermediate filaments and IF-associated proteins: from cell architecture to cell proliferation. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2019; 95:479-493. [PMID: 31611503 PMCID: PMC6819152 DOI: 10.2183/pjab.95.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2019] [Accepted: 07/08/2019] [Indexed: 05/05/2023]
Abstract
Intermediate filaments (IFs), in coordination with microfilaments and microtubules, form the structural framework of the cytoskeleton and nucleus, thereby providing mechanical support against cellular stresses and anchoring intracellular organelles in place. The assembly and disassembly of IFs are mainly regulated by the phosphorylation of IF proteins. These phosphorylation states can be tracked using antibodies raised against phosphopeptides in the target proteins. IFs exert their functions through interactions with not only structural proteins, but also non-structural proteins involved in cell signaling, such as stress responses, apoptosis, and cell proliferation. This review highlights findings related to how IFs regulate cell division through phosphorylation cascades and how trichoplein, a centriolar protein originally identified as a keratin-associated protein, regulates the cell cycle through primary cilium formation.
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Affiliation(s)
- Yuhei NISHIMURA
- Departments of Integrative Pharmacology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Kousuke KASAHARA
- Department of Physiology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
| | - Masaki INAGAKI
- Department of Physiology, Mie University Graduate School of Medicine, Tsu, Mie, Japan
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Lin CH, Shen YR, Wang HY, Chiang CW, Wang CY, Kuo PL. Regulation of septin phosphorylation: SEPT12 phosphorylation in sperm septin assembly. Cytoskeleton (Hoboken) 2018; 76:137-142. [PMID: 30160375 DOI: 10.1002/cm.21491] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 08/08/2018] [Accepted: 08/12/2018] [Indexed: 12/11/2022]
Abstract
The sperm annulus, a septin-based ring structure, is important for reproductive physiology. It is composed of SEPT12-based septin core complex followed by assembling as octameric filament. In clinical examinations, mutations of Septin12 result in male infertility, immotile sperm, as well as sperm with defective annuli. The dynamic assembly of septin filaments is regulated by several post-translational modifications, including sumoylation, acetylation, and phosphorylation. Here, we briefly review the biological significance and the regulation of SEPT12 phosphorylation in the mammalian sperm physiology. During mammalian spermiogenesis, the phosphorylation of SEPT12 on Ser198 residue is important in regulating mammalian annulus architectures. SEPT12 phosphomimetic knock-in mice displayed poor male fertility due to weak sperm motility and loss of the sperm annulus. SEPT12 is phosphorylated via Protein kinase A (PKA), and its phosphorylation interfered with SEPT12 polymerization into complexes and filaments. Taken together, the phosphorylation status of SEPT12 is crucial for its function in regulating the mammalian sperm physiology.
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Affiliation(s)
- Chun-Hsiang Lin
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Yi-Ru Shen
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Han-Yu Wang
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chi-Wu Chiang
- Institute of Molecular Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Chia-Yih Wang
- Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Pao-Lin Kuo
- Department of Obstetrics and Gynecology, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Institute of Basic Medical Sciences, College of Medicine, National Cheng Kung University, Tainan, Taiwan.,Department of Obstetrics and Gynecology, National Cheng-Kung University Hospital, Tainan, Taiwan
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