1
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Cavini IA, Fontes MG, Zeraik AE, Lopes JLS, Araujo APU. Novel lipid-interaction motifs within the C-terminal domain of Septin10 from Schistosoma mansoni. BIOCHIMICA ET BIOPHYSICA ACTA. BIOMEMBRANES 2024; 1866:184371. [PMID: 39025256 DOI: 10.1016/j.bbamem.2024.184371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2024] [Revised: 07/05/2024] [Accepted: 07/15/2024] [Indexed: 07/20/2024]
Abstract
Septins are cytoskeletal proteins and their interaction with membranes is crucial for their role in various cellular processes. Septins have polybasic regions (PB1 and PB2) which are important for lipid interaction. Earlier, we and others have highlighted the role of the septin C-terminal domain (CTD) to membrane interaction. However, detailed information on residues/group of residues important for such feature is lacking. In this study, we investigate the lipid-binding profile of Schistosoma mansoni Septin10 (SmSEPT10) using PIP strip and Langmuir monolayer adsorption assays. Our findings highlight the CTD as the primary domain responsible for lipid interaction in SmSEPT10, showing binding to phosphatidylinositol phosphates. SmSEPT10 CTD contains a conserved polybasic region (PB3) present in both animals and fungi septins, and a Lys (K367) within its putative amphipathic helix (AH) that we demonstrate as important for lipid binding. PB3 deletion or mutation of this Lys (K367A) strongly impairs lipid interaction. Remarkably, we observe that the AH within a construct lacking the final 43 amino acid residues is insufficient for lipid binding. Furthermore, we investigate the homocomplex formed by SmSEPT10 CTD in solution by cross-linking experiments, CD spectroscopy, SEC-MALS and SEC-SAXS. Taken together, our studies define the lipid-binding region in SmSEPT10 and offer insights into the molecular basis of septin-membrane binding. This information is particularly relevant for less-studied non-human septins, such as SmSEPT10.
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Affiliation(s)
- Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, SP 13560-970, Brazil; School of Pharmaceutical Sciences of Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP 14040-903, Brazil
| | - Marina G Fontes
- São Carlos Institute of Physics, University of São Paulo, São Carlos, SP 13560-970, Brazil; Department of Pharmaceutical Technology, School of Pharmaceutical Sciences, University of São Paulo, São Paulo, SP 05508-000, Brazil
| | - Ana Eliza Zeraik
- Laboratory of Chemistry and Function of Proteins and Peptides, Center for Biosciences and Biotechnology, North Fluminense State University Darcy Ribeiro, Campos dos Goytacazes, RJ 28013-602, Brazil
| | - Jose L S Lopes
- Laboratory of Molecular Biophysics, Department of Physics, Faculty of Philosophy, Sciences and Letters at Ribeirão Preto, University of São Paulo, Ribeirão Preto, SP 14040-901, Brazil
| | - Ana Paula U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, SP 13560-970, Brazil.
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2
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Delic S, Shuman B, Lee S, Bahmanyar S, Momany M, Onishi M. The evolutionary origins and ancestral features of septins. Front Cell Dev Biol 2024; 12:1406966. [PMID: 38994454 PMCID: PMC11238149 DOI: 10.3389/fcell.2024.1406966] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 05/08/2024] [Indexed: 07/13/2024] Open
Abstract
Septins are a family of membrane-associated cytoskeletal guanine-nucleotide binding proteins that play crucial roles in various cellular processes, such as cell division, phagocytosis, and organelle fission. Despite their importance, the evolutionary origins and ancestral function of septins remain unclear. In opisthokonts, septins form five distinct groups of orthologs, with subunits from multiple groups assembling into heteropolymers, thus supporting their diverse molecular functions. Recent studies have revealed that septins are also conserved in algae and protists, indicating an ancient origin from the last eukaryotic common ancestor. However, the phylogenetic relationships among septins across eukaryotes remained unclear. Here, we expanded the list of non-opisthokont septins, including previously unrecognized septins from glaucophyte algae. Constructing a rooted phylogenetic tree of 254 total septins, we observed a bifurcation between the major non-opisthokont and opisthokont septin clades. Within the non-opisthokont septins, we identified three major subclades: Group 6 representing chlorophyte green algae (6A mostly for species with single septins, 6B for species with multiple septins), Group 7 representing algae in chlorophytes, heterokonts, haptophytes, chrysophytes, and rhodophytes, and Group 8 representing ciliates. Glaucophyte and some ciliate septins formed orphan lineages in-between all other septins and the outgroup. Combining ancestral-sequence reconstruction and AlphaFold predictions, we tracked the structural evolution of septins across eukaryotes. In the GTPase domain, we identified a conserved GAP-like arginine finger within the G-interface of at least one septin in most algal and ciliate species. This residue is required for homodimerization of the single Chlamydomonas septin, and its loss coincided with septin duplication events in various lineages. The loss of the arginine finger is often accompanied by the emergence of the α0 helix, a known NC-interface interaction motif, potentially signifying the diversification of septin-septin interaction mechanisms from homo-dimerization to hetero-oligomerization. Lastly, we found amphipathic helices in all septin groups, suggesting that membrane binding is an ancestral trait. Coiled-coil domains were also broadly distributed, while transmembrane domains were found in some septins in Group 6A and 7. In summary, this study advances our understanding of septin distribution and phylogenetic groupings, shedding light on their ancestral features, potential function, and early evolution.
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Affiliation(s)
- Samed Delic
- Department of Biology, Duke University, Durham, NC, United States
| | - Brent Shuman
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, GA, United States
| | - Shoken Lee
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT, United States
| | - Shirin Bahmanyar
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, CT, United States
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, GA, United States
| | - Masayuki Onishi
- Department of Biology, Duke University, Durham, NC, United States
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3
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López-Jiménez AT, Özbaykal Güler G, Mostowy S. The great escape: a Shigella effector unlocks the septin cage. Nat Commun 2024; 15:4104. [PMID: 38750009 PMCID: PMC11096336 DOI: 10.1038/s41467-024-48208-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 04/19/2024] [Indexed: 05/18/2024] Open
Affiliation(s)
- Ana T López-Jiménez
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Gizem Özbaykal Güler
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK.
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4
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Raab JE, Hamilton DJ, Harju TB, Huynh TN, Russo BC. Pushing boundaries: mechanisms enabling bacterial pathogens to spread between cells. Infect Immun 2024:e0052423. [PMID: 38661369 DOI: 10.1128/iai.00524-23] [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] [Indexed: 04/26/2024] Open
Abstract
For multiple intracellular bacterial pathogens, the ability to spread directly into adjacent epithelial cells is an essential step for disease in humans. For pathogens such as Shigella, Listeria, Rickettsia, and Burkholderia, this intercellular movement frequently requires the pathogens to manipulate the host actin cytoskeleton and deform the plasma membrane into structures known as protrusions, which extend into neighboring cells. The protrusion is then typically resolved into a double-membrane vacuole (DMV) from which the pathogen quickly escapes into the cytosol, where additional rounds of intercellular spread occur. Significant progress over the last few years has begun to define the mechanisms by which intracellular bacterial pathogens spread. This review highlights the interactions of bacterial and host factors that drive mechanisms required for intercellular spread with a focus on how protrusion structures form and resolve.
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Affiliation(s)
- Julie E Raab
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Desmond J Hamilton
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Tucker B Harju
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Thao N Huynh
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
| | - Brian C Russo
- Department of Immunology and Microbiology, School of Medicine, University of Colorado-Anschutz Medical Campus, Denver, Colorado, USA
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5
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Delic S, Shuman B, Lee S, Bahmanyar S, Momany M, Onishi M. The Evolutionary Origins and Ancestral Features of Septins. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.25.586683. [PMID: 38585751 PMCID: PMC10996617 DOI: 10.1101/2024.03.25.586683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/09/2024]
Abstract
Septins are a family of membrane-associated cytoskeletal GTPases that play crucial roles in various cellular processes, such as cell division, phagocytosis, and organelle fission. Despite their importance, the evolutionary origins and ancestral function of septins remain unclear. In opisthokonts, septins form five distinct groups of orthologs, with subunits from multiple groups assembling into heteropolymers, thus supporting their diverse molecular functions. Recent studies have revealed that septins are also conserved in algae and protists, indicating an ancient origin from the last eukaryotic common ancestor. However, the phylogenetic relationships among septins across eukaryotes remained unclear. Here, we expanded the list of non-opisthokont septins, including previously unrecognized septins from rhodophyte red algae and glaucophyte algae. Constructing a rooted phylogenetic tree of 254 total septins, we observed a bifurcation between the major non-opisthokont and opisthokont septin clades. Within the non-opisthokont septins, we identified three major subclades: Group 6 representing chlorophyte green algae (6A mostly for species with single septins, 6B for species with multiple septins), Group 7 representing algae in chlorophytes, heterokonts, haptophytes, chrysophytes, and rhodophytes, and Group 8 representing ciliates. Glaucophyte and some ciliate septins formed orphan lineages in-between all other septins and the outgroup. Combining ancestral-sequence reconstruction and AlphaFold predictions, we tracked the structural evolution of septins across eukaryotes. In the GTPase domain, we identified a conserved GAP-like arginine finger within the G-interface of at least one septin in most algal and ciliate species. This residue is required for homodimerization of the single Chlamydomonas septin, and its loss coincided with septin duplication events in various lineages. The loss of the arginine finger is often accompanied by the emergence of the α0 helix, a known NC-interface interaction motif, potentially signifying the diversification of septin-septin interaction mechanisms from homo-dimerization to hetero-oligomerization. Lastly, we found amphipathic helices in all septin groups, suggesting that curvature-sensing is an ancestral trait of septin proteins. Coiled-coil domains were also broadly distributed, while transmembrane domains were found in some septins in Group 6A and 7. In summary, this study advances our understanding of septin distribution and phylogenetic groupings, shedding light on their ancestral features, potential function, and early evolution.
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Affiliation(s)
- Samed Delic
- Department of Biology, Duke University, Durham, North Carolina, USA
| | - Brent Shuman
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, Georgia, USA
| | - Shoken Lee
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Shirin Bahmanyar
- Department of Molecular Cellular and Developmental Biology, Yale University, New Haven, Connecticut, USA
| | - Michelle Momany
- Fungal Biology Group and Plant Biology Department, University of Georgia, Athens, Georgia, USA
| | - Masayuki Onishi
- Department of Biology, Duke University, Durham, North Carolina, USA
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6
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Xu Y, Ding K, Peng T. Chemical Proteomics Reveals N ε-Fatty-Acylation of Septins by Rho Inactivation Domain (RID) of the Vibrio MARTX Toxin to Alter Septin Localization and Organization. Mol Cell Proteomics 2024; 23:100730. [PMID: 38311109 PMCID: PMC10924143 DOI: 10.1016/j.mcpro.2024.100730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 01/16/2024] [Accepted: 01/31/2024] [Indexed: 02/06/2024] Open
Abstract
Vibrio species, the Gram-negative bacterial pathogens causing cholera and sepsis, produce multiple secreted virulence factors for infection and pathogenesis. Among these is the multifunctional-autoprocessing repeats-in-toxin (MARTX) toxin that releases several critical effector domains with distinct functions inside eukaryotic host cells. One such effector domain, the Rho inactivation domain (RID), has been discovered to catalyze long-chain Nε-fatty-acylation on lysine residues of Rho GTPases, causing inactivation of Rho GTPases and disruption of the host actin cytoskeleton. However, whether RID modifies other host proteins to exert additional functions remains to be determined. Herein, we describe the integration of bioorthogonal chemical labeling and quantitative proteomics to globally profile the target proteins modified by RID in living cells. More than 246 proteins are identified as new RID substrates, including many involved in GTPase regulation, cytoskeletal organization, and cell division. We demonstrate that RID extensively Nε-fatty-acylates septin proteins, the fourth cytoskeletal component of mammalian cells with important roles in diverse cellular processes. While affinity purification and mass spectrometry analysis show that RID-mediated Nε-fatty-acylation does not affect septin-septin interactions, this modification increases the membrane association of septins and confers localization to detergent-resistant membrane rafts. As a result, the filamentous assembly and organization of septins are disrupted by RID-mediated Nε-fatty-acylation, further contributing to cytoskeletal and mitotic defects that phenocopy the effects of septin depletion. Overall, our work greatly expands the substrate scope and function of RID and demonstrates the role of RID-mediated Nε-fatty-acylation in manipulating septin localization and organization.
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Affiliation(s)
- Yaxin Xu
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Ke Ding
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China
| | - Tao Peng
- State Key Laboratory of Chemical Oncogenomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen, China; Shenzhen Bay Laboratory, Institute of Chemical Biology, Shenzhen, China.
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7
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Nakazawa K, Chauvin B, Mangenot S, Bertin A. Reconstituted in vitro systems to reveal the roles and functions of septins. J Cell Sci 2023; 136:jcs259448. [PMID: 37815088 DOI: 10.1242/jcs.259448] [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] [Indexed: 10/11/2023] Open
Abstract
Septins are essential cytoskeletal proteins involved in key cellular processes and have also been implicated in diseases from cancers to neurodegenerative pathologies. However, they have not been as thoroughly studied as other cytoskeletal proteins. In vivo, septins interact with other cytoskeletal proteins and with the inner plasma membrane. Hence, bottom-up in vitro cell-free assays are well suited to dissect the roles and behavior of septins in a controlled environment. Specifically, in vitro studies have been invaluable in describing the self-assembly of septins into a large diversity of ultrastructures. Given that septins interact specifically with membrane, the details of these septin-membrane interactions have been analyzed using reconstituted lipid systems. In particular, at a membrane, septins are often localized at curvatures of micrometer scale. In that context, in vitro assays have been performed with substrates of varying curvatures (spheres, cylinders or undulated substrates) to probe the sensitivity of septins to membrane curvature. This Review will first present the structural properties of septins in solution and describe the interplay of septins with cytoskeletal partners. We will then discuss how septins interact with biomimetic membranes and induce their reshaping. Finally, we will highlight the curvature sensitivity of septins and how they alter the mechanical properties of membranes.
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Affiliation(s)
- Koyomi Nakazawa
- Physico Chimie Curie , Institut Curie, CNRS UMR 168, Sorbonne Université, 11 Rue Pierre et Paris Curie, 75005 Paris, France
| | - Brieuc Chauvin
- Physico Chimie Curie , Institut Curie, CNRS UMR 168, Sorbonne Université, 11 Rue Pierre et Paris Curie, 75005 Paris, France
| | - Stéphanie Mangenot
- Laboratoire Matière et Systèmes Complexes , Université de Paris Cité, CNRS UMR 7057, 45 Rue des Saint Pères, 75006 Paris, France
| | - Aurélie Bertin
- Physico Chimie Curie , Institut Curie, CNRS UMR 168, Sorbonne Université, 11 Rue Pierre et Paris Curie, 75005 Paris, France
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8
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Mageswaran SK, Grotjahn DA, Zeng X, Barad BA, Medina M, Hoang MH, Dobro MJ, Chang YW, Xu M, Yang WY, Jensen GJ. Nanoscale details of mitochondrial constriction revealed by cryoelectron tomography. Biophys J 2023; 122:3768-3782. [PMID: 37533259 PMCID: PMC10541493 DOI: 10.1016/j.bpj.2023.07.030] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2023] [Revised: 07/14/2023] [Accepted: 07/31/2023] [Indexed: 08/04/2023] Open
Abstract
Mitochondria adapt to changing cellular environments, stress stimuli, and metabolic demands through dramatic morphological remodeling of their shape, and thus function. Such mitochondrial dynamics is often dependent on cytoskeletal filament interactions. However, the precise organization of these filamentous assemblies remains speculative. Here, we apply cryogenic electron tomography to directly image the nanoscale architecture of the cytoskeletal-membrane interactions involved in mitochondrial dynamics in response to damage. We induced mitochondrial damage via membrane depolarization, a cellular stress associated with mitochondrial fragmentation and mitophagy. We find that, in response to acute membrane depolarization, mammalian mitochondria predominantly organize into tubular morphology that abundantly displays constrictions. We observe long bundles of both unbranched actin and septin filaments enriched at these constrictions. We also observed septin-microtubule interactions at these sites and elsewhere, suggesting that these two filaments guide each other in the cytosolic space. Together, our results provide empirical parameters for the architecture of mitochondrial constriction factors to validate/refine existing models and inform the development of new ones.
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Affiliation(s)
- Shrawan Kumar Mageswaran
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Danielle Ann Grotjahn
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California.
| | - Xiangrui Zeng
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Benjamin Asher Barad
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California
| | - Michaela Medina
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, California
| | - My Hanh Hoang
- Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | | | - Yi-Wei Chang
- Department of Biophysics and Biochemistry, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Institute of Structural Biology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Min Xu
- Computational Biology Department, School of Computer Science, Carnegie Mellon University, Pittsburgh, Pennsylvania
| | - Wei Yuan Yang
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Grant J Jensen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California; Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah.
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9
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Gomes MC, Brokatzky D, Bielecka MK, Wardle FC, Mostowy S. Shigella induces epigenetic reprogramming of zebrafish neutrophils. SCIENCE ADVANCES 2023; 9:eadf9706. [PMID: 37672585 PMCID: PMC10482349 DOI: 10.1126/sciadv.adf9706] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2022] [Accepted: 08/03/2023] [Indexed: 09/08/2023]
Abstract
Trained immunity is a long-term memory of innate immune cells, generating an improved response upon reinfection. Shigella is an important human pathogen and inflammatory paradigm for which there is no effective vaccine. Using zebrafish larvae, we demonstrate that after Shigella training, neutrophils are more efficient at bacterial clearance. We observe that Shigella-induced protection is nonspecific and has differences with training by BCG and β-glucan. Analysis of histone ChIP-seq on trained neutrophils revealed that Shigella training deposits the active H3K4me3 mark on promoter regions of 1612 genes, dramatically changing the epigenetic landscape of neutrophils toward enhanced microbial recognition and mitochondrial ROS production. Last, we demonstrate that mitochondrial ROS plays a key role in enhanced antimicrobial activity of trained neutrophils. It is envisioned that signals and mechanisms we discover here can be used in other vertebrates, including humans, to suggest new therapeutic strategies involving neutrophils to control bacterial infection.
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Affiliation(s)
- Margarida C. Gomes
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Dominik Brokatzky
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Magdalena K. Bielecka
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
| | - Fiona C. Wardle
- Randall Centre for Cell and Molecular Biophysics, New Hunt's House, Guy's Campus, King's College London, UK
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, London, UK
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10
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Sharma K, Menon MB. Decoding post-translational modifications of mammalian septins. Cytoskeleton (Hoboken) 2023; 80:169-181. [PMID: 36797225 DOI: 10.1002/cm.21747] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2022] [Revised: 01/21/2023] [Accepted: 02/10/2023] [Indexed: 02/18/2023]
Abstract
Septins are cytoskeletal GTPases that form nonpolar filaments and higher-ordered structures and they take part in a wide range of cellular processes. Septins are conserved from yeast to mammals but absent from higher plants. The number of septin genes vary between organisms and they usually form complex heteropolymeric networks. Most septins are known to be capable of GTP hydrolysis which may regulate septin dynamics. Knowledge on regulation of septin function by post-translational modifications is still in its infancy. In this review article, we highlight the post-translational modifications reported for the 13 human septins and discuss their implications on septin functions. In addition to the functionally investigated modifications, we also try to make sense of the complex septin post-translational modification code revealed from large-scale phospho-proteomic datasets. Future studies may determine how these isoform-specific and homology group specific modifications affect septin structure and function.
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Affiliation(s)
- Khushboo Sharma
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Manoj B Menon
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
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11
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Torraca V, Bielecka MK, Gomes MC, Brokatzky D, Busch‐Nentwich EM, Mostowy S. Zebrafish null mutants of Sept6 and Sept15 are viable but more susceptible to Shigella infection. Cytoskeleton (Hoboken) 2023; 80:266-274. [PMID: 36855298 PMCID: PMC10952258 DOI: 10.1002/cm.21750] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Revised: 01/21/2023] [Accepted: 02/24/2023] [Indexed: 03/02/2023]
Abstract
Septins are evolutionarily conserved GTP-binding proteins known for their roles in cell division and host defence against Shigella infection. Although septin group members are viewed to function as hetero-oligomeric complexes, the role of individual septins within these complexes or in isolation is poorly understood. Decades of work using mouse models has shown that some septins (including SEPT7) are essential for animal development, while others (including SEPT6) are dispensable, suggesting that some septins may compensate for the absence of others. The zebrafish genome encodes 19 septin genes, representing the full complement of septin groups described in mice and humans. In this report, we characterise null mutants for zebrafish Sept6 (a member of the SEPT6 group) and Sept15 (a member of the SEPT7 group) and test their role in zebrafish development and host defence against Shigella infection. We show that null mutants for Sept6 and Sept15 are both viable, and that expression of other zebrafish septins are not significantly affected by their mutation. Consistent with previous reports using knockdown of Sept2, Sept7b, and Sept15, we show that Sept6 and Sept15 are required for host defence against Shigella infection. These results highlight Shigella infection of zebrafish as a powerful system to study the role of individual septins in vivo.
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Affiliation(s)
- Vincenzo Torraca
- Department of Infection BiologyLondon School of Hygiene & Tropical MedicineLondonUK
- School of Life SciencesUniversity of WestminsterLondonUK
| | | | - Margarida C. Gomes
- Department of Infection BiologyLondon School of Hygiene & Tropical MedicineLondonUK
| | - Dominik Brokatzky
- Department of Infection BiologyLondon School of Hygiene & Tropical MedicineLondonUK
| | - Elisabeth M. Busch‐Nentwich
- Department of Medicine, Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID)University of CambridgeCambridgeUK
- School of Biological and Behavioural Sciences, Faculty of Science and EngineeringQueen Mary University of LondonLondonUK
| | - Serge Mostowy
- Department of Infection BiologyLondon School of Hygiene & Tropical MedicineLondonUK
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12
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Van Ngo H, Robertin S, Brokatzky D, Bielecka MK, Lobato‐Márquez D, Torraca V, Mostowy S. Septins promote caspase activity and coordinate mitochondrial apoptosis. Cytoskeleton (Hoboken) 2023; 80:254-265. [PMID: 35460543 PMCID: PMC10952901 DOI: 10.1002/cm.21696] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/08/2022] [Accepted: 04/05/2022] [Indexed: 11/06/2022]
Abstract
Apoptosis is a form of regulated cell death essential for tissue homeostasis and embryonic development. Apoptosis also plays a key role during bacterial infection, yet some intracellular bacterial pathogens (such as Shigella flexneri, whose lipopolysaccharide can block apoptosis) can manipulate cell death programs as an important survival strategy. Septins are a component of the cytoskeleton essential for mitochondrial dynamics and host defense, however, the role of septins in regulated cell death is mostly unknown. Here, we discover that septins promote mitochondrial (i.e., intrinsic) apoptosis in response to treatment with staurosporine (a pan-kinase inhibitor) or etoposide (a DNA topoisomerase inhibitor). Consistent with a role for septins in mitochondrial dynamics, septins promote the release of mitochondrial protein cytochrome c in apoptotic cells and are required for the proteolytic activation of caspase-3, caspase-7, and caspase-9 (core components of the apoptotic machinery). Apoptosis of HeLa cells induced in response to infection by S. flexneri ΔgalU (a lipopolysaccharide mutant unable to block apoptosis) is also septin-dependent. In vivo, zebrafish larvae are significantly more susceptible to infection with S. flexneri ΔgalU (as compared to infection with wildtype S. flexneri), yet septin deficient larvae are equally susceptible to infection with S. flexneri ΔgalU and wildtype S. flexneri. These data provide a new molecular framework to understand the complexity of mitochondrial apoptosis and its ability to combat bacterial infection.
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Affiliation(s)
- Hoan Van Ngo
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Stevens Robertin
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Dominik Brokatzky
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Magdalena K. Bielecka
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Damián Lobato‐Márquez
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Vincenzo Torraca
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
- School of Life SciencesUniversity of WestminsterLondonUK
| | - Serge Mostowy
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
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13
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B.R. R, Shah N, Joshi P, Madhusudan MS, Balasubramanian N. Kinetics of Arf1 inactivation regulates Golgi organisation and function in non-adherent fibroblasts. Biol Open 2023; 12:bio059669. [PMID: 36946871 PMCID: PMC10187640 DOI: 10.1242/bio.059669] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 03/13/2023] [Indexed: 03/23/2023] Open
Abstract
Arf1 belongs to the Arf family of small GTPases that localise at the Golgi and plasma membrane. Active Arf1 plays a crucial role in regulating Golgi organisation and function. In mouse fibroblasts, loss of adhesion triggers a consistent drop (∼50%) in Arf1 activation that causes the Golgi to disorganise but not fragment. In suspended cells, the trans-Golgi (GalTase) disperses more prominently than cis-Golgi (Man II), accompanied by increased active Arf1 (detected using GFP-ABD: ARHGAP10 Arf1 binding domain) associated with the cis-Golgi compartment. Re-adhesion restores Arf1 activation at the trans-Golgi as it reorganises. Arf1 activation at the Golgi is regulated by Arf1 Guanine nucleotide exchange factors (GEFs), GBF1, and BIG1/2. In non-adherent fibroblasts, the cis-medial Golgi provides a unique setting to test and understand the role GEF-mediated Arf1 activation has in regulating Golgi organisation. Labelled with Man II-GFP, non-adherent fibroblasts treated with increasing concentrations of Brefeldin-A (BFA) (which inhibits BIG1/2 and GBF1) or Golgicide A (GCA) (which inhibits GBF1 only) comparably decrease active Arf1 levels. They, however, cause a concentration-dependent increase in cis-medial Golgi fragmentation and fusion with the endoplasmic reticulum (ER). Using selected BFA and GCA concentrations, we find a change in the kinetics of Arf1 inactivation could mediate this by regulating cis-medial Golgi localisation of GBF1. On loss of adhesion, a ∼50% drop in Arf1 activation over 120 min causes the Golgi to disorganise. The kinetics of this drop, when altered by BFA or GCA treatment causes a similar decline in Arf1 activation but over 10 min. This causes the Golgi to now fragment which affects cell surface glycosylation and re-adherent cell spreading. Using non-adherent fibroblasts this study reveals the kinetics of Arf1 inactivation, with active Arf1 levels, to be vital for Golgi organisation and function.
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Affiliation(s)
- Rajeshwari B.R.
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Nikita Shah
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Prachi Joshi
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - M. S. Madhusudan
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Nagaraj Balasubramanian
- Indian Institute of Science Education and Research (IISER) Pune, Dr Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
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14
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Lobato-Márquez D, Conesa JJ, López-Jiménez AT, Divine ME, Pruneda JN, Mostowy S. Septins and K63 ubiquitin chains are present in separate bacterial microdomains during autophagy of entrapped Shigella. J Cell Sci 2023; 136:jcs261139. [PMID: 36939083 PMCID: PMC10264824 DOI: 10.1242/jcs.261139] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Accepted: 03/07/2023] [Indexed: 03/21/2023] Open
Abstract
During host cell invasion, Shigella escapes to the cytosol and polymerizes actin for cell-to-cell spread. To restrict cell-to-cell spread, host cells employ cell-autonomous immune responses including antibacterial autophagy and septin cage entrapment. How septins interact with the autophagy process to target Shigella for destruction is poorly understood. Here, we employed a correlative light and cryo-soft X-ray tomography (cryo-SXT) pipeline to study Shigella septin cage entrapment in its near-native state. Quantitative cryo-SXT showed that Shigella fragments mitochondria and enabled visualization of X-ray-dense structures (∼30 nm resolution) surrounding Shigella entrapped in septin cages. Using Airyscan confocal microscopy, we observed lysine 63 (K63)-linked ubiquitin chains decorating septin-cage-entrapped Shigella. Remarkably, septins and K63 chains are present in separate bacterial microdomains, indicating they are recruited separately during antibacterial autophagy. Cryo-SXT and live-cell imaging revealed an interaction between septins and LC3B-positive membranes during autophagy of Shigella. Together, these findings demonstrate how septin-caged Shigella are targeted for autophagy and provide fundamental insights into autophagy-cytoskeleton interactions.
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Affiliation(s)
- Damián Lobato-Márquez
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - José Javier Conesa
- MISTRAL beamline, ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Barcelona, Spain
| | - Ana Teresa López-Jiménez
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Michael E. Divine
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Jonathan N. Pruneda
- Department of Molecular Microbiology & Immunology, Oregon Health & Science University, Portland, OR 97239, USA
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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15
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Weems AD, Welf ES, Driscoll MK, Zhou FY, Mazloom-Farsibaf H, Chang BJ, Murali VS, Gihana GM, Weiss BG, Chi J, Rajendran D, Dean KM, Fiolka R, Danuser G. Blebs promote cell survival by assembling oncogenic signalling hubs. Nature 2023; 615:517-525. [PMID: 36859545 PMCID: PMC10881276 DOI: 10.1038/s41586-023-05758-6] [Citation(s) in RCA: 32] [Impact Index Per Article: 32.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 01/25/2023] [Indexed: 03/03/2023]
Abstract
Most human cells require anchorage for survival. Cell-substrate adhesion activates diverse signalling pathways, without which cells undergo anoikis-a form of programmed cell death1. Acquisition of anoikis resistance is a pivotal step in cancer disease progression, as metastasizing cells often lose firm attachment to surrounding tissue2,3. In these poorly attached states, cells adopt rounded morphologies and form small hemispherical plasma membrane protrusions called blebs4-11. Bleb function has been thoroughly investigated in the context of amoeboid migration, but it has been examined far less in other scenarios12. Here we show by three-dimensional imaging and manipulation of cell morphological states that blebbing triggers the formation of plasma membrane-proximal signalling hubs that confer anoikis resistance. Specifically, in melanoma cells, blebbing generates plasma membrane contours that recruit curvature-sensing septin proteins as scaffolds for constitutively active mutant NRAS and effectors. These signalling hubs activate ERK and PI3K-well-established promoters of pro-survival pathways. Inhibition of blebs or septins has little effect on the survival of well-adhered cells, but in detached cells it causes NRAS mislocalization, reduced MAPK and PI3K activity, and ultimately, death. This unveils a morphological requirement for mutant NRAS to operate as an effective oncoprotein. Furthermore, whereas some BRAF-mutated melanoma cells do not rely on this survival pathway in a basal state, inhibition of BRAF and MEK strongly sensitizes them to both bleb and septin inhibition. Moreover, fibroblasts engineered to sustain blebbing acquire the same anoikis resistance as cancer cells even without harbouring oncogenic mutations. Thus, blebs are potent signalling organelles capable of integrating myriad cellular information flows into concerted cellular responses, in this case granting robust anoikis resistance.
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Affiliation(s)
- Andrew D Weems
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA.
| | - Erik S Welf
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
- Regeneron Pharmaceuticals, Tarrytown, NY, USA
| | - Meghan K Driscoll
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
- Department of Pharmacology, University of Minnesota, Minneapolis, MN, USA
| | - Felix Y Zhou
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | | | - Bo-Jui Chang
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Vasanth S Murali
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Gabriel M Gihana
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Byron G Weiss
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Joseph Chi
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Divya Rajendran
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Kevin M Dean
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Reto Fiolka
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA
| | - Gaudenz Danuser
- Lyda Hill Department of Bioinformatics, UT Southwestern Medical Center, Dallas, TX, USA.
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16
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Benoit B, Poüs C, Baillet A. Septins as membrane influencers: direct play or in association with other cytoskeleton partners. Front Cell Dev Biol 2023; 11:1112319. [PMID: 36875762 PMCID: PMC9982393 DOI: 10.3389/fcell.2023.1112319] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/23/2023] [Indexed: 02/19/2023] Open
Abstract
The cytoskeleton comprises three polymerizing structures that have been studied for a long time, actin microfilaments, microtubules and intermediate filaments, plus more recently investigated dynamic assemblies like septins or the endocytic-sorting complex required for transport (ESCRT) complex. These filament-forming proteins control several cell functions through crosstalks with each other and with membranes. In this review, we report recent works that address how septins bind to membranes, and influence their shaping, organization, properties and functions, either by binding to them directly or indirectly through other cytoskeleton elements.
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Affiliation(s)
- Béatrice Benoit
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
| | - Christian Poüs
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France.,Laboratoire de Biochimie-Hormonologie, Hôpital Antoine Béclère, AP-HP, Hôpitaux Universitaires Paris-Saclay, Clamart, France
| | - Anita Baillet
- INSERM UMR-S 1193, UFR de Pharmacie, University Paris-Saclay, Orsay, France
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17
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Hartland EL, Ghosal D, Giogha C. Manipulation of epithelial cell architecture by the bacterial pathogens Listeria and Shigella. Curr Opin Cell Biol 2022; 79:102131. [PMID: 36215855 DOI: 10.1016/j.ceb.2022.102131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2022] [Revised: 08/22/2022] [Accepted: 09/06/2022] [Indexed: 01/31/2023]
Abstract
Subversion of the host cell cytoskeleton is a virulence attribute common to many bacterial pathogens. On mucosal surfaces, bacteria have evolved distinct ways of interacting with the polarised epithelium and manipulating host cell structure to propagate infection. For example, Shigella and Listeria induce cytoskeletal changes to induce their own uptake into enterocytes in order to replicate within an intracellular environment and then spread from cell-to-cell by harnessing the host actin cytoskeleton. In this review, we highlight some recent studies that advance our understanding of the role of the host cell cytoskeleton in the mechanical and molecular processes of pathogen invasion, cell-to-cell spread and the impact of infection on epithelial intercellular tension and innate mucosal defence.
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Affiliation(s)
- Elizabeth L Hartland
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia; Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia.
| | - Debnath Ghosal
- Department of Biochemistry and Pharmacology, Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC, Australia
| | - Cristina Giogha
- Centre for Innate Immunity and Infectious Diseases, Hudson Institute of Medical Research, Clayton, Victoria, Australia; Department of Molecular and Translational Science, Monash University, Clayton, Victoria, Australia
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18
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Odendall C, Sa Pessoa J, Mesquita FS. Meeting report - Cell dynamics: host-pathogen interface. J Cell Sci 2022; 135:276364. [PMID: 35979931 DOI: 10.1242/jcs.260456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two years into the most significant infectious disease event of our generation, infections have populated every conversation and in-depth understanding of host-pathogen interactions has, perhaps, never been more important. In a successful return to in-person conferences, the host-pathogen interface was the focus of the third Cell Dynamics meeting, which took place at the glorious Wotton House in Surrey, UK. The meeting organised by Michaela Gack, Maximiliano Gutierrez, Dominique Soldati-Favre and Michael Way gathered an international group of scientists who shared their recent discoveries and views on numerous aspects, including cell-autonomous defence mechanisms, pathogen interactions with host cytoskeletal or membrane dynamics, and cellular immune regulation. More than 30 years into the beginning of cellular microbiology as a field, the meeting exhibited the unique aspect of the host-pathogen interface in uncovering the fundamentals of both pathogens and their hosts.
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Affiliation(s)
- Charlotte Odendall
- Department of Infectious Diseases, School of Immunology and Microbial Sciences, King's College London, SE1 9RT London, UK
| | - Joana Sa Pessoa
- Wellcome-Wolfson Institute for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, BT9 7BL Belfast, UK
| | - Francisco S Mesquita
- Global Health Institute, School of Life Sciences, EPFL, CH-1015 Lausanne, Switzerland
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19
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Abstract
Pyroptosis, a regulated form of pro-inflammatory cell death, is characterised by cell lysis and by the release of cytokines, damage- and pathogen-associated molecular patterns. It plays an important role during bacterial infection, where it can promote an inflammatory response and eliminate the replicative niche of intracellular pathogens. Recent work, using a variety of bacterial pathogens, has illuminated the versatility of pyroptosis, revealing unexpected and important concepts underlying host defence. In this Review, we overview the molecular mechanisms underlying pyroptosis and discuss their role in host defence, from the single cell to the whole organism. We focus on recent studies using three cellular microbiology paradigms - Mycobacterium tuberculosis, Salmonella Typhimurium and Shigella flexneri - that have transformed the field of pyroptosis. We compare insights discovered in tissue culture, zebrafish and mouse models, highlighting the advantages and disadvantages of using these complementary infection models to investigate pyroptosis and for modelling human infection. Moving forward, we propose that in-depth knowledge of pyroptosis obtained from complementary infection models can better inform future studies using higher vertebrates, including humans, and help develop innovative host-directed therapies to combat bacterial infection.
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Affiliation(s)
- Dominik Brokatzky
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, UK
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20
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Rubio-Miranda JÁ, Cázares-Raga FE, Coy-Arechavaleta AS, Viettri M, Cortes-Martínez L, Lagunes-Guillén A, Chavez-Munguía B, Ludert JE, Hernández-Hernández FDLC. Septin 2 interacts with dengue virus replication complex proteins and participates in virus replication in mosquito cells. Virology 2022; 570:67-80. [DOI: 10.1016/j.virol.2022.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Revised: 02/05/2022] [Accepted: 03/24/2022] [Indexed: 11/16/2022]
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21
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Baillet A, McMurray MA, Oakes PW. Meeting report - the ever-fascinating world of septins. J Cell Sci 2021; 134:jcs259552. [PMID: 34910818 PMCID: PMC10658896 DOI: 10.1242/jcs.259552] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Septins are GTP-binding proteins that assemble into hetero-oligomers. They can interact with each other end-to-end to form filaments, making them the fourth element of the cytoskeleton. To update the current knowledge on the ever-increasing implications of these fascinating proteins in cellular functions, a hundred expert scientists from across the globe gathered from 12 to 15 October 2021 in Berlin for the first hybrid-format (on site and virtual) EMBO workshop Molecular and Cell Biology of Septins.
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Affiliation(s)
- Anita Baillet
- INSERM UMR-S 1193, Faculté de Pharmacie, Université Paris-Saclay, 92290 Châtenay-Malabry, France
| | - Michael A. McMurray
- Department of Cell and Developmental Biology, University of Colorado Anschutz Medical Campus, Aurora, CO 80045, USA
| | - Patrick W. Oakes
- Department of Cell & Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153USA
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22
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Schuster T, Geiger H. Septins in Stem Cells. Front Cell Dev Biol 2021; 9:801507. [PMID: 34957123 PMCID: PMC8695968 DOI: 10.3389/fcell.2021.801507] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Accepted: 11/24/2021] [Indexed: 12/01/2022] Open
Abstract
Septins were first described in yeast. Due to extensive research in non-yeast cells, Septins are now recognized across all species as important players in the regulation of the cytoskeleton, in the establishment of polarity, for migration, vesicular trafficking and scaffolding. Stem cells are primarily quiescent cells, and this actively maintained quiescent state is critical for proper stem cell function. Equally important though, stem cells undergo symmetric or asymmetric division, which is likely linked to the level of symmetry found in the mother stem cell. Due to the ability to organize barriers and be able to break symmetry in cells, Septins are thought to have a significant impact on organizing quiescence as well as the mode (symmetric vs asymmetric) of stem cell division to affect self-renewal versus differentiation. Mechanisms of regulating mammalian quiescence and symmetry breaking by Septins are though still somewhat elusive. Within this overview article, we summarize current knowledge on the role of Septins in stem cells ranging from yeast to mice especially with respect to quiescence and asymmetric division, with a special focus on hematopoietic stem cells.
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Affiliation(s)
| | - Hartmut Geiger
- Institute of Molecular Medicine, Ulm University, Ulm, Germany
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23
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Emerging technologies and infection models in cellular microbiology. Nat Commun 2021; 12:6764. [PMID: 34799563 PMCID: PMC8604907 DOI: 10.1038/s41467-021-26641-w] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Accepted: 10/18/2021] [Indexed: 01/09/2023] Open
Abstract
The field of cellular microbiology, rooted in the co-evolution of microbes and their hosts, studies intracellular pathogens and their manipulation of host cell machinery. In this review, we highlight emerging technologies and infection models that recently promoted opportunities in cellular microbiology. We overview the explosion of microscopy techniques and how they reveal unprecedented detail at the host-pathogen interface. We discuss the incorporation of robotics and artificial intelligence to image-based screening modalities, biochemical mapping approaches, as well as dual RNA-sequencing techniques. Finally, we describe chips, organoids and animal models used to dissect biophysical and in vivo aspects of the infection process. As our knowledge of the infected cell improves, cellular microbiology holds great promise for development of anti-infective strategies with translational applications in human health.
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24
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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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