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Prislusky MI, Lam JGT, Contreras VR, Ng M, Chamberlain M, Pathak-Sharma S, Fields M, Zhang X, Amer AO, Seveau S. The septin cytoskeleton is required for plasma membrane repair. EMBO Rep 2024:10.1038/s44319-024-00195-6. [PMID: 38969946 DOI: 10.1038/s44319-024-00195-6] [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: 03/27/2024] [Revised: 05/30/2024] [Accepted: 06/07/2024] [Indexed: 07/07/2024] Open
Abstract
Plasma membrane repair is a fundamental homeostatic process of eukaryotic cells. Here, we report a new function for the conserved cytoskeletal proteins known as septins in the repair of cells perforated by pore-forming toxins or mechanical disruption. Using a silencing RNA screen, we identified known repair factors (e.g. annexin A2, ANXA2) and novel factors such as septin 7 (SEPT7) that is essential for septin assembly. Upon plasma membrane injury, the septin cytoskeleton is extensively redistributed to form submembranous domains arranged as knob and loop structures containing F-actin, myosin IIA, S100A11, and ANXA2. Formation of these domains is Ca2+-dependent and correlates with plasma membrane repair efficiency. Super-resolution microscopy revealed that septins and F-actin form intertwined filaments associated with ANXA2. Depletion of SEPT7 prevented ANXA2 recruitment and formation of submembranous actomyosin domains. However, ANXA2 depletion had no effect on domain formation. Collectively, our data support a novel septin-based mechanism for resealing damaged cells, in which the septin cytoskeleton plays a key structural role in remodeling the plasma membrane by promoting the formation of SEPT/F-actin/myosin IIA/ANXA2/S100A11 repair domains.
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Affiliation(s)
- M Isabella Prislusky
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Jonathan G T Lam
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Viviana Ruiz Contreras
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
- Grupo Investigaciones Biomédicas, Universidad de Sucre, Sincelejo, Sucre, Colombia
| | - Marilynn Ng
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Madeline Chamberlain
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Sarika Pathak-Sharma
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Madalyn Fields
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Xiaoli Zhang
- Department of Biomedical Informatics, The Ohio State University, Columbus, OH, USA
| | - Amal O Amer
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA
| | - Stephanie Seveau
- Department of Microbial Infection & Immunity, Wexner Medical Center, The Ohio State University, Columbus, OH, USA.
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2
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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] [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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3
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Khairat J, Hatta M, Abdullah N, Azman A, Calvin S, Syed Hassan S. Unearthing the role of septins in viral infections. Biosci Rep 2024; 44:BSR20231827. [PMID: 38372298 PMCID: PMC10920062 DOI: 10.1042/bsr20231827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 01/15/2024] [Accepted: 01/18/2024] [Indexed: 02/20/2024] Open
Abstract
Septin proteins are a subfamily of closely related GTP-binding proteins conserved in all species except for higher plants and perform essential biological processes. Septins self-assemble into heptameric or octameric complexes and form higher-order structures such as filaments, rings, or gauzes by end-to-end binding. Their close association with cell membrane components makes them central in regulating critical cellular processes. Due to their organisation and properties, septins function as diffusion barriers and are integral in providing scaffolding to support the membrane's curvature and stability of its components. Septins are also involved in vesicle transport and exocytosis through the plasma membrane by co-localising with exocyst protein complexes. Recently, there have been emerging reports of several human and animal diseases linked to septins and abnormalities in their functions. Most of our understanding of the significance of septins during microbial diseases mainly pertains to their roles in bacterial infections but not viruses. This present review focuses on the known roles of septins in host-viral interactions as detailed by various studies.
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Affiliation(s)
- Jasmine Elanie Khairat
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Muhammad Nur Adam Hatta
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Nurshariza Abdullah
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Selangor, Malaysia
- School of Health Sciences, Universiti Sains Malaysia, Kubang Kerian 16150, Kelantan, Malaysia
| | - Adzzie Shazleen Azman
- School of Science, Monash University Malaysia, Bandar Sunway 47500, Selangor, Malaysia
| | - Shee Yin Ming Calvin
- Institute of Biological Sciences (ISB), Faculty of Science, Universiti Malaya, Kuala Lumpur 50603, Malaysia
| | - Sharifah Syed Hassan
- Jeffrey Cheah School of Medicine and Health Sciences, Monash University Malaysia, Bandar Sunway 47500, Selangor, Malaysia
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4
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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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5
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Perucho-Jaimes L, Do J, Van Elgort A, Kaplan KB. Septins modulate the autophagy response after nutrient starvation. Mol Biol Cell 2024; 35:ar4. [PMID: 37910217 PMCID: PMC10881159 DOI: 10.1091/mbc.e22-11-0520] [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: 11/18/2022] [Revised: 09/19/2023] [Accepted: 10/16/2023] [Indexed: 11/03/2023] Open
Abstract
The pathways that induce macroautophagy (referred to as autophagy hereafter) in response to the stress of starvation are well conserved and essential under nutrient-limiting conditions. However, less is understood about the mechanisms that modulate the autophagy response. Here we present evidence that after induction of autophagy in budding yeast septin filaments rapidly assemble into discrete patches distributed along the cell cortex. These patches gradually mature over 12 h of nutrient deprivation to form extended structures around Atg9 membranes tethered at the cortical endoplasmic reticulum, a class of membranes that are limiting for autophagosome biogenesis. Loss of cortical septin structures alters the kinetics of autophagy activation and most dramatically extends the duration of the autophagy response. In wild-type cells, diffusion of Atg9 membranes at the cell cortex undergoes transient pauses that are dependent on septins, and septins at the bud neck block the diffusion of Atg9 membranes between mother and daughter cells. We conclude that septins reorganize at the cell cortex during autophagy to locally limit access of Atg9 membranes to autophagosome assembly sites, and thus modulate the autophagy response during nutrient deprivation.
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Affiliation(s)
- Luis Perucho-Jaimes
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Jonathan Do
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Alexandria Van Elgort
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
| | - Kenneth B. Kaplan
- Department of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616
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Liu H, Yan P, Wu C, Rao M, Zhu J, Lv L, Li W, Liang Y, Qi S, Lu K, Kong E. Palmitoylated Sept8-204 modulates learning and anxiety by regulating filopodia arborization and actin dynamics. Sci Signal 2023; 16:eadi8645. [PMID: 38051778 DOI: 10.1126/scisignal.adi8645] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 11/02/2023] [Indexed: 12/07/2023]
Abstract
Septin proteins are involved in diverse physiological functions, including the formation of specialized cytoskeletal structures. Septin 8 (Sept8) is implicated in spine morphogenesis and dendritic branching through palmitoylation. We explored the role and regulation of a Sept8 variant in human neural-like cells and in the mouse brain. We identified Sept8-204 as a brain-specific variant of Sept8 that was abundant in neurons and modified by palmitoylation, specifically at Cys469, Cys470, and Cys472. Sept8-204 palmitoylation was mediated by the palmitoyltransferase ZDHHC7 and was removed by the depalmitoylase PPT1. Palmitoylation of Sept8-204 bound to F-actin and induced cytoskeletal dynamics to promote the outgrowth of filopodia in N2a cells and the arborization of neurites in hippocampal neurons. In contrast, a Sept8-204 variant that could not be palmitoylated because of mutation of all three Cys residues (Sept8-204-3CA) lost its ability to bind F-actin, and expression of this mutant did not promote morphological changes. Genetic deletion of Sept8, Sept8-204, or Zdhhc7 caused deficits in learning and memory and promoted anxiety-like behaviors in mice. Our findings provide greater insight into the regulation of Sept8-204 by palmitoylation and its role in neuronal morphology and function in relation to cognition.
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Affiliation(s)
- Huicong Liu
- Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
| | - Peipei Yan
- Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
| | - Can Wu
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
| | - Muding Rao
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
| | - Jiangli Zhu
- Department of Urology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and National Collaborative Innovation Center, Chengdu 610041, China
| | - Luxian Lv
- Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
| | - Wenqiang Li
- Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
| | - Yinming Liang
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
| | - Shiqian Qi
- Department of Urology, State Key Laboratory of Biotherapy and Cancer Center, West China Hospital, Sichuan University and National Collaborative Innovation Center, Chengdu 610041, China
| | - Kefeng Lu
- Department of Neurology, State Key Laboratory of Biotherapy, West China Hospital, Sichuan University, Chengdu 610065, China
| | - Eryan Kong
- Second Affiliated Hospital of Xinxiang Medical University, Xinxiang 453003, China
- Institute of Psychiatry and Neuroscience, Xinxiang Key Laboratory of Protein Palmitoylation and Major Human Diseases, Xinxiang Medical University, Xinxiang 453003, China
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7
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Robertin S, Brokatzky D, Lobato-Márquez D, Mostowy S. Regulation of integrin α5β1-mediated Staphylococcus aureus cellular invasion by the septin cytoskeleton. Eur J Cell Biol 2023; 102:151359. [PMID: 37683588 DOI: 10.1016/j.ejcb.2023.151359] [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: 04/05/2023] [Revised: 08/10/2023] [Accepted: 09/01/2023] [Indexed: 09/10/2023] Open
Abstract
Staphylococcus aureus, a Gram-positive bacterial pathogen, is an urgent health threat causing a wide range of clinical infections. Originally viewed as a strict extracellular pathogen, accumulating evidence has revealed S. aureus to be a facultative intracellular pathogen subverting host cell signalling to support invasion. The majority of clinical isolates produce fibronectin-binding proteins A and B (FnBPA and FnBPB) to interact with host integrin α5β1, a key component of focal adhesions. S. aureus binding of integrin α5β1 promotes its clustering on the host cell surface, triggering activation of focal adhesion kinase (FAK) and cytoskeleton rearrangements to promote bacterial invasion into non-phagocytic cells. Here, we discover that septins, a component of the cytoskeleton that assembles on membranes, are recruited as collar-like structures with actin to S. aureus invasion sites engaging integrin α5β1. To investigate septin recruitment to the plasma membrane in a bacteria-free system, we used FnBPA-coated latex beads and showed that septins are recruited upon activation of integrin α5β1. SEPT2 depletion reduced S. aureus invasion, but increased surface expression of integrin α5 and adhesion of S. aureus to host cells. Consistent with this, SEPT2 depletion increased cellular protein levels of integrin α5 and β1 subunits, as well as FAK. Collectively, these results provide insights into regulation of integrin α5β1 and invasion of S. aureus by the septin cytoskeleton.
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Affiliation(s)
- Stevens Robertin
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Dominik Brokatzky
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Damián Lobato-Márquez
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Serge Mostowy
- Department of Infection Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
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8
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Fu B, Xiong Y, Sha Z, Xue W, Xu B, Tan S, Guo D, Lin F, Wang L, Ji J, Luo Y, Lin X, Wu H. SEPTIN2 suppresses an IFN-γ-independent, proinflammatory macrophage activation pathway. Nat Commun 2023; 14:7441. [PMID: 37978190 PMCID: PMC10656488 DOI: 10.1038/s41467-023-43283-2] [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: 02/13/2023] [Accepted: 11/06/2023] [Indexed: 11/19/2023] Open
Abstract
Interferon-gamma (IFN-γ) signaling is necessary for the proinflammatory activation of macrophages but IFN-γ-independent pathways, for which the initiating stimuli and downstream mechanisms are lesser known, also contribute. Here we identify, by high-content screening, SEPTIN2 (SEPT2) as a negative regulation of IFN-γ-independent macrophage autoactivation. Mechanistically, endoplasmic reticulum (ER) stress induces the expression of SEPT2, which balances the competition between acetylation and ubiquitination of heat shock protein 5 at position Lysine 327, thereby alleviating ER stress and constraining M1-like polarization and proinflammatory cytokine release. Disruption of this negative feedback regulation leads to the accumulation of unfolded proteins, resulting in accelerated M1-like polarization, excessive inflammation and tissue damage. Our study thus uncovers an IFN-γ-independent macrophage proinflammatory autoactivation pathway and suggests that SEPT2 may play a role in the prevention or resolution of inflammation during infection.
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Affiliation(s)
- Beibei Fu
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Yan Xiong
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Zhou Sha
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Weiwei Xue
- School of Pharmaceutical Sciences, Chongqing University, 401331, Chongqing, China
| | - Binbin Xu
- School of Pharmaceutical Sciences, Chongqing University, 401331, Chongqing, China
| | - Shun Tan
- Chongqing Public Health Medical Center, 400036, Chongqing, China
| | - Dong Guo
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Feng Lin
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Lulu Wang
- School of Life Sciences, Chongqing University, 401331, Chongqing, China
| | - Jianjian Ji
- Jiangsu Key Laboratory of Pediatric Respiratory Disease, Institute of Pediatrics, Nanjing University of Chinese Medicine, 210023, Nanjing, China
| | - Yang Luo
- Center of Smart Laboratory and Molecular Medicine, School of Medicine, NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing University, 400044, Chongqing, China.
| | - Xiaoyuan Lin
- Institut für Virologie, Freie Universität Berlin, Robert-von-Ostertag-Str. 7-13, 14163, Berlin, Germany.
- Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), 400038, Chongqing, China.
| | - Haibo Wu
- School of Life Sciences, Chongqing University, 401331, Chongqing, China.
- Center of Smart Laboratory and Molecular Medicine, School of Medicine, NHC Key Laboratory of Birth Defects and Reproductive Health, Chongqing University, 400044, Chongqing, China.
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9
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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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10
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de Freitas Fernandes A, Leonardo DA, Cavini IA, Rosa HVD, Vargas JA, D'Muniz Pereira H, Nascimento AS, Garratt RC. Conservation and divergence of the G-interfaces of Drosophila melanogaster septins. Cytoskeleton (Hoboken) 2023; 80:153-168. [PMID: 36576069 DOI: 10.1002/cm.21740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2022] [Revised: 12/19/2022] [Accepted: 12/26/2022] [Indexed: 12/29/2022]
Abstract
Septins possess a conserved guanine nucleotide-binding (G) domain that participates in the stabilization of organized hetero-oligomeric complexes which assemble into filaments, rings and network-like structures. The fruit fly, Drosophila melanogaster, has five such septin genes encoding Sep1, Sep2, Sep4, Sep5 and Pnut. Here, we report the crystal structure of the heterodimer formed between the G-domains of Sep1 and Sep2, the first from an insect to be described to date. A G-interface stabilizes the dimer (in agreement with the expected arrangement for the Drosophila hexameric particle) and this bears significant resemblance to its human counterparts, even down to the level of individual amino acid interactions. On the other hand, a model for the G-interface formed between the two copies of Pnut which occupy the centre of the hexamer, shows important structural differences, including the loss of a highly favourable bifurcated salt-bridge network. Whereas wild-type Pnut purifies as a monomer, the reintroduction of the salt-bridge network results in stabilizing the dimeric interface in solution as shown by size exclusion chromatography and thermal stability measurements. Adaptive steered molecular dynamics reveals an unzipping mechanism for dimer dissociation which initiates at a point of electrostatic repulsion within the switch II region. Overall, the data contribute to a better understanding of the molecular interactions involved in septin assembly/disassembly.
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Affiliation(s)
| | | | | | | | - Jhon Antoni Vargas
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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11
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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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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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14
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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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15
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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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16
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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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17
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Eslamloo K, Kumar S, Xue X, Parrish KS, Purcell SL, Fast MD, Rise ML. Global gene expression responses of Atlantic salmon skin to Moritella viscosa. Sci Rep 2022; 12:4622. [PMID: 35301338 PMCID: PMC8931016 DOI: 10.1038/s41598-022-08341-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2021] [Accepted: 03/03/2022] [Indexed: 12/19/2022] Open
Abstract
Moritella viscosa is a Gram-negative pathogen that causes large, chronic ulcers, known as winter-ulcer disease, in the skin of several fish species including Atlantic salmon. We used a bath challenge approach to profile the transcriptome responses of M. viscosa-infected Atlantic salmon skin at the lesion (Mv-At) and away from the lesion (Mv-Aw) sites. M. viscosa infection was confirmed through RNA-based qPCR assays. RNA-Seq identified 5212 and 2911 transcripts differentially expressed in the Mv-At compared to no-infection control and Mv-Aw groups, respectively. Also, there were 563 differentially expressed transcripts when comparing the Mv-Aw to control samples. Our results suggest that M. viscosa caused massive and strong, but largely infection site-focused, transcriptome dysregulations in Atlantic salmon skin, and its effects beyond the skin lesion site were comparably subtle. The M. viscosa-induced transcripts of Atlantic salmon were mainly involved in innate and adaptive immune response-related pathways, whereas the suppressed transcripts by this pathogen were largely connected to developmental and cellular processes. As validated by qPCR, M. viscosa dysregulated transcripts encoding receptors, signal transducers, transcription factors and immune effectors playing roles in TLR- and IFN-dependent pathways as well as immunoregulation, antigen presentation and T-cell development. This study broadened the current understanding of molecular pathways underlying M. viscosa-triggered responses of Atlantic salmon, and identified biomarkers that may assist to diagnose and combat this pathogen.
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Affiliation(s)
- Khalil Eslamloo
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada. .,Hoplite Laboratory, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada.
| | - Surendra Kumar
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Xi Xue
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
| | - Kathleen S Parrish
- Hoplite Laboratory, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada
| | - Sara L Purcell
- Hoplite Laboratory, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada
| | - Mark D Fast
- Hoplite Laboratory, Department of Pathology and Microbiology, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PEI, Canada
| | - Matthew L Rise
- Department of Ocean Sciences, Memorial University of Newfoundland, St. John's, NL, Canada
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18
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Menon MB, Yakovleva T, Ronkina N, Suwandi A, Odak I, Dhamija S, Sandrock I, Hansmann F, Baumgärtner W, Förster R, Kotlyarov A, Gaestel M. Lyz2-Cre-Mediated Genetic Deletion of Septin7 Reveals a Role of Septins in Macrophage Cytokinesis and Kras-Driven Tumorigenesis. Front Cell Dev Biol 2022; 9:795798. [PMID: 35071236 PMCID: PMC8772882 DOI: 10.3389/fcell.2021.795798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Accepted: 12/16/2021] [Indexed: 01/22/2023] Open
Abstract
By crossing septin7-floxed mice with Lyz2-Cre mice carrying the Cre recombinase inserted in the Lysozyme-M (Lyz2) gene locus we aimed the specific deletion of septin7 in myeloid cells, such as monocytes, macrophages and granulocytes. Septin7 flox/flox :Lyz2-Cre mice show no alterations in the myeloid compartment. Septin7-deleted macrophages (BMDMs) were isolated and analyzed. The lack of Septin7 expression was confirmed and a constitutive double-nucleation was detected in Septin7-deficient BMDMs indicating a defect in macrophage cytokinesis. However, phagocytic function of macrophages as judged by uptake of labelled E. coli particles and LPS-stimulated macrophage activation as judged by induction of TNF mRNA expression and TNF secretion were not compromised. In addition to myeloid cells, Lyz2-Cre is also active in type II pneumocytes (AT2 cells). We monitored lung adenocarcinoma formation in these mice by crossing them with the conditional knock-in Kras-LSL-G12D allele. Interestingly, we found that control mice without septin7 depletion die after 3-5 weeks, while the Septin7-deficient animals survived 11 weeks or even longer. Control mice sacrificed in the age of 4 weeks display a bronchiolo-alveolar hyperplasia with multiple adenomas, whereas the Septin7-deficient animals of the same age are normal or show only a weak multifocal brochiolo-alveolar hyperplasia. Our findings indicate an essential role of Septin7 in macrophage cytokinesis but not in macrophage function. Furthermore, septin7 seems absolutely essential for oncogenic Kras-driven lung tumorigenesis making it a potential target for anti-tumor interventions.
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Affiliation(s)
- Manoj B Menon
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany.,Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, New Delhi, India
| | - Tatiana Yakovleva
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Natalia Ronkina
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Abdulhadi Suwandi
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Ivan Odak
- Institute of Immunology, Hannover Medical School, Hannover, Germany
| | - Sonam Dhamija
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany.,Institute of Genomics and Integrative Biology (CSIR-IGIB), New Delhi, India
| | - Inga Sandrock
- Institute of Immunology, Hannover Medical School, Hannover, Germany
| | - Florian Hansmann
- Institute of Pathology, Stiftung Tierärztliche Hochschule, Hannover, Germany.,Institute of Veterinary Pathology, Veterinary Faculty of Leipzig University, Leipzig, Germany
| | | | - Reinhold Förster
- Institute of Immunology, Hannover Medical School, Hannover, Germany
| | - Alexey Kotlyarov
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
| | - Matthias Gaestel
- Institute of Cell Biochemistry, Hannover Medical School, Hannover, Germany
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19
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Cavini IA, Leonardo DA, Rosa HVD, Castro DKSV, D'Muniz Pereira H, Valadares NF, Araujo APU, Garratt RC. The Structural Biology of Septins and Their Filaments: An Update. Front Cell Dev Biol 2021; 9:765085. [PMID: 34869357 PMCID: PMC8640212 DOI: 10.3389/fcell.2021.765085] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Accepted: 10/27/2021] [Indexed: 01/22/2023] Open
Abstract
In order to fully understand any complex biochemical system from a mechanistic point of view, it is necessary to have access to the three-dimensional structures of the molecular components involved. Septins and their oligomers, filaments and higher-order complexes are no exception. Indeed, the spontaneous recruitment of different septin monomers to specific positions along a filament represents a fascinating example of subtle molecular recognition. Over the last few years, the amount of structural information available about these important cytoskeletal proteins has increased dramatically. This has allowed for a more detailed description of their individual domains and the different interfaces formed between them, which are the basis for stabilizing higher-order structures such as hexamers, octamers and fully formed filaments. The flexibility of these structures and the plasticity of the individual interfaces have also begun to be understood. Furthermore, recently, light has been shed on how filaments may bundle into higher-order structures by the formation of antiparallel coiled coils involving the C-terminal domains. Nevertheless, even with these advances, there is still some way to go before we fully understand how the structure and dynamics of septin assemblies are related to their physiological roles, including their interactions with biological membranes and other cytoskeletal components. In this review, we aim to bring together the various strands of structural evidence currently available into a more coherent picture. Although it would be an exaggeration to say that this is complete, recent progress seems to suggest that headway is being made in that direction.
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Affiliation(s)
- Italo A Cavini
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Diego A Leonardo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Higor V D Rosa
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Danielle K S V Castro
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil.,São Carlos Institute of Chemistry, University of São Paulo, São Carlos, Brazil
| | | | | | - Ana P U Araujo
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
| | - Richard C Garratt
- São Carlos Institute of Physics, University of São Paulo, São Carlos, Brazil
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20
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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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21
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Woods BL, Gladfelter AS. The state of the septin cytoskeleton from assembly to function. Curr Opin Cell Biol 2020; 68:105-112. [PMID: 33188984 DOI: 10.1016/j.ceb.2020.10.007] [Citation(s) in RCA: 64] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2020] [Revised: 10/01/2020] [Accepted: 10/08/2020] [Indexed: 01/09/2023]
Abstract
Septins are conserved guanine nucleotide-binding proteins that polymerize into filaments at the cell cortex or in association with other cytoskeletal proteins, such as actin or microtubules. As integral players in many morphogenic and signaling events, septins form scaffolds important for the recruitment of the cytokinetic machinery, organization of the plasma membrane, and orientation of cell polarity. Mutations in septins or their misregulation are associated with numerous diseases. Despite growing appreciation for the importance of septins in different aspects of cell biology and disease, septins remain relatively poorly understood compared with other cytoskeletal proteins. Here in this review, we highlight some of the recent developments of the last two years in the field of septin cell biology.
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Affiliation(s)
- Benjamin L Woods
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA
| | - Amy S Gladfelter
- Biology Department, University of North Carolina, Chapel Hill, NC, 27599, USA; Marine Biological Laboratory, Woods Hole, MA, 02543, USA.
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22
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Muñoz-Sánchez S, van der Vaart M, Meijer AH. Autophagy and Lc3-Associated Phagocytosis in Zebrafish Models of Bacterial Infections. Cells 2020; 9:cells9112372. [PMID: 33138004 PMCID: PMC7694021 DOI: 10.3390/cells9112372] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/24/2020] [Accepted: 10/28/2020] [Indexed: 02/06/2023] Open
Abstract
Modeling human infectious diseases using the early life stages of zebrafish provides unprecedented opportunities for visualizing and studying the interaction between pathogens and phagocytic cells of the innate immune system. Intracellular pathogens use phagocytes or other host cells, like gut epithelial cells, as a replication niche. The intracellular growth of these pathogens can be counteracted by host defense mechanisms that rely on the autophagy machinery. In recent years, zebrafish embryo infection models have provided in vivo evidence for the significance of the autophagic defenses and these models are now being used to explore autophagy as a therapeutic target. In line with studies in mammalian models, research in zebrafish has shown that selective autophagy mediated by ubiquitin receptors, such as p62, is important for host resistance against several bacterial pathogens, including Shigella flexneri, Mycobacterium marinum, and Staphylococcus aureus. Furthermore, an autophagy related process, Lc3-associated phagocytosis (LAP), proved host beneficial in the case of Salmonella Typhimurium infection but host detrimental in the case of S. aureus infection, where LAP delivers the pathogen to a replication niche. These studies provide valuable information for developing novel therapeutic strategies aimed at directing the autophagy machinery towards bacterial degradation.
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