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Gulen B, Casey A, Orth K. AMPylation of small GTPases by Fic enzymes. FEBS Lett 2023; 597:883-891. [PMID: 36239538 PMCID: PMC10050140 DOI: 10.1002/1873-3468.14516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Revised: 09/17/2022] [Accepted: 10/06/2022] [Indexed: 12/14/2022]
Abstract
Small GTPases orchestrate numerous cellular pathways, acting as molecular switches and regulatory hubs to transmit molecular signals and because of this, they are often the target of pathogens. During infection, pathogens manipulate host cellular networks using post-translational modifications (PTMs). AMPylation, the modification of proteins with AMP, has been identified as a common PTM utilized by pathogens to hijack GTPase signalling during infection. AMPylation is primarily carried out by enzymes with a filamentation induced by cyclic-AMP (Fic) domain. Modification of small GTPases by AMP renders GTPases impervious to upstream regulatory inputs, resulting in unregulated downstream effector outputs for host cellular processes. Here, we overview Fic-mediated AMPylation of small GTPases by pathogens and other related PTMs catalysed by Fic enzymes on GTPases.
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Affiliation(s)
- Burak Gulen
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Amanda Casey
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, UT Southwestern Medical Center, Dallas, TX and Howard Hughes Medical Institute, Dallas, TX, USA
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2
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Zhang Q, Wan M, Mao Y. Membrane-dependent actin polymerization mediated by the Legionella pneumophila effector protein MavH. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.01.24.525393. [PMID: 36747622 PMCID: PMC9900769 DOI: 10.1101/2023.01.24.525393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
L. pneumophila propagates in eukaryotic cells within a specialized niche, the Legionella -containing vacuole (LCV). The infection process is controlled by over 330 effector proteins delivered through the type IV secretion system. In this study, we report that the Legionella MavH effector harbors a lipid-binding domain that specifically recognizes PI(3)P (phosphatidylinositol 3-phosphate) and localizes to endosomes when ectopically expressed. We show that MavH recruits host actin capping proteins (CP) and actin to the endosome via its CP interacting (CPI) motif and WH2-like actin-binding domain, respectively. In vitro assays revealed that MavH stimulates robust actin polymerization only in the presence of PI(3)P-containing liposomes and the recruitment of CP by MavH negatively regulates F-actin density at the membrane. Furthermore, in L. pneumophila -infected cells, MavH can be detected around the LCV at the very early stage of infection. Together, our results reveal a novel mechanism of membrane-dependent actin polymerization catalyzed by MavH that may play a role at the early stage of L. pneumophila infection by regulating host actin dynamics.
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Affiliation(s)
- Qing Zhang
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.,Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Min Wan
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.,Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Yuxin Mao
- Weill Institute for Cell and Molecular Biology, Cornell University, Ithaca, NY 14853, USA.,Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA.,Corresponding Author: , Telephone: 607-255-0783
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3
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Structural basis for selective AMPylation of Rac-subfamily GTPases by Bartonella effector protein 1 (Bep1). Proc Natl Acad Sci U S A 2021; 118:2023245118. [PMID: 33723071 PMCID: PMC8000347 DOI: 10.1073/pnas.2023245118] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
Mammalian cells regulate diverse cellular processes in response to extracellular cues. Small GTPases of the Rho family act as molecular switches to rapidly regulate discrete cellular activities, such as cytoskeletal dynamics, cell movement, and innate immune responses. Numerous bacterial virulence factors modulate the function of Rho-family GTPases and thereby manipulate intracellular signaling. For many of these virulence factors we have gained detailed understanding how they covalently modify individual Rho-family GTPases to reprogram their activities; however, their mechanisms of selective targeting of distinct subsets of Rho-family GTPases remained elusive. Using a combination of structural biology and biochemistry, we demonstrate for the effector protein Bep1 exclusive specificity for Rac-subfamily GTPases and propose the underlying mechanism of target selectivity. Small GTPases of the Ras-homology (Rho) family are conserved molecular switches that control fundamental cellular activities in eukaryotic cells. As such, they are targeted by numerous bacterial toxins and effector proteins, which have been intensively investigated regarding their biochemical activities and discrete target spectra; however, the molecular mechanism of target selectivity has remained largely elusive. Here we report a bacterial effector protein that selectively targets members of the Rac subfamily in the Rho family of small GTPases but none in the closely related Cdc42 or RhoA subfamilies. This exquisite target selectivity of the FIC domain AMP-transferase Bep1 from Bartonella rochalimae is based on electrostatic interactions with a subfamily-specific pair of residues in the nucleotide-binding G4 motif and the Rho insert helix. Residue substitutions at the identified positions in Cdc42 enable modification by Bep1, while corresponding Cdc42-like substitutions in Rac1 greatly diminish modification. Our study establishes a structural understanding of target selectivity toward Rac-subfamily GTPases and provides a highly selective tool for their functional analysis.
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4
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Lemichez E, Popoff MR, Satchell KJF. Cellular microbiology: Bacterial toxin interference drives understanding of eukaryotic cell function. Cell Microbiol 2021; 22:e13178. [PMID: 32185903 DOI: 10.1111/cmi.13178] [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: 10/04/2019] [Revised: 11/04/2019] [Accepted: 11/08/2019] [Indexed: 11/28/2022]
Abstract
Intimate interactions between the armament of pathogens and their host dictate tissue and host susceptibility to infection also forging specific pathophysiological outcomes. Studying these interactions at the molecular level has provided an invaluable source of knowledge on cellular processes, as ambitioned by the Cellular Microbiology discipline when it emerged in early 90s. Bacterial toxins act on key cell regulators or membranes to produce major diseases and therefore constitute a remarkable toolbox for dissecting basic biological processes. Here, we review selected examples of recent studies on bacterial toxins illustrating how fruitful the discipline of cellular microbiology is in shaping our understanding of eukaryote processes. This ever-renewing discipline unveils new virulence factor biochemical activities shared by eukaryotic enzymes and hidden rules of cell proteome homeostasis, a particularly promising field to interrogate the impact of proteostasis breaching in late onset human diseases. It is integrating new concepts from the physics of soft matter to capture biomechanical determinants forging cells and tissues architecture. The success of this discipline is also grounded by the development of therapeutic tools and new strategies to treat both infectious and noncommunicable human diseases.
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Affiliation(s)
- Emmanuel Lemichez
- Unité des Toxines Bactériennes, CNRS ERL6002, Institut Pasteur, Paris, France
| | | | - Karla J F Satchell
- Department of Microbiology-Immunology, Northwestern University, Feinberg School of Medicine, Chicago, Illinois
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5
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Marlaire S, Dehio C. Bartonella effector protein C mediates actin stress fiber formation via recruitment of GEF-H1 to the plasma membrane. PLoS Pathog 2021; 17:e1008548. [PMID: 33508040 PMCID: PMC7842960 DOI: 10.1371/journal.ppat.1008548] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2020] [Accepted: 10/09/2020] [Indexed: 02/06/2023] Open
Abstract
Bartonellae are Gram-negative facultative-intracellular pathogens that use a type-IV-secretion system (T4SS) to translocate a cocktail of Bartonella effector proteins (Beps) into host cells to modulate diverse cellular functions. BepC was initially reported to act in concert with BepF in triggering major actin cytoskeletal rearrangements that result in the internalization of a large bacterial aggregate by the so-called ‘invasome’. Later, infection studies with bepC deletion mutants and ectopic expression of BepC have implicated this effector in triggering an actin-dependent cell contractility phenotype characterized by fragmentation of migrating cells due to deficient rear detachment at the trailing edge, and BepE was shown to counterbalance this remarkable phenotype. However, the molecular mechanism of how BepC triggers cytoskeletal changes and the host factors involved remained elusive. Using infection assays, we show here that T4SS-mediated transfer of BepC is sufficient to trigger stress fiber formation in non-migrating epithelial cells and additionally cell fragmentation in migrating endothelial cells. Interactomic analysis revealed binding of BepC to a complex of the Rho guanine nucleotide exchange factor GEF-H1 and the serine/threonine-protein kinase MRCKα. Knock-out cell lines revealed that only GEF-H1 is required for mediating BepC-triggered stress fiber formation and inhibitor studies implicated activation of the RhoA/ROCK pathway downstream of GEF-H1. Ectopic co-expression of tagged versions of GEF-H1 and BepC truncations revealed that the C-terminal ‘Bep intracellular delivery’ (BID) domain facilitated anchorage of BepC to the plasma membrane, whereas the N-terminal ‘filamentation induced by cAMP’ (FIC) domain facilitated binding of GEF-H1. While FIC domains typically mediate post-translational modifications, most prominently AMPylation, a mutant with quadruple amino acid exchanges in the putative active site indicated that the BepC FIC domain acts in a non-catalytic manner to activate GEF-H1. Our data support a model in which BepC activates the RhoA/ROCK pathway by re-localization of GEF-H1 from microtubules to the plasma membrane. A wide variety of bacterial pathogens evolved numerous virulence factors to subvert cellular processes in support of a successful infection process. Likewise, bacteria of the genus Bartonella translocate a cocktail of effector proteins (Beps) via a type-IV-secretion system into infected cells in order to interfere with host signaling processes involved in cytoskeletal dynamics, apoptosis control, and innate immune responses. In this study, we demonstrate that BepC triggers actin stress fiber formation and a linked cell fragmentation phenotype resulting from distortion of rear-end retraction during cell migration. The ability of BepC to induce actin stress fiber formation is directly associated with its ability to bind GEF-H1, an activator of the RhoA pathway that is sequestered in an inactive state when bound to microtubules but becomes activated upon release to the cytoplasm. Our findings suggest that BepC is anchored via its BID domain to the plasma membrane where it recruits GEF-H1 via its FIC domain, eventually activating the RhoA/ROCK signaling pathway and leading to stress fiber formation.
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Affiliation(s)
| | - Christoph Dehio
- Biozentrum, University of Basel, Basel, Switzerland
- * E-mail:
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6
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The N-terminus of Paenibacillus larvae C3larvinA modulates catalytic efficiency. Biosci Rep 2021; 41:227200. [PMID: 33289829 PMCID: PMC7789906 DOI: 10.1042/bsr20203727] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 12/07/2020] [Accepted: 12/08/2020] [Indexed: 01/21/2023] Open
Abstract
C3larvinA was recently described as a mono-ADP-ribosyltransferase (mART) toxin from the enterobacterial repetitive intergenic consensus (ERIC) III genotype of the agricultural pathogen, Paenibacillus larvae. It was shown to be the full-length, functional version of the previously described C3larvintrunc toxin, due to a 33-residue extension of the N-terminus of the protein. In the present study, a series of deletions and substitutions were made to the N-terminus of C3larvinA to assess the contribution of the α1-helix to toxin structure and function. Catalytic characterization of these variants identified Asp23 and Ala31 residues as supportive to enzymatic function. A third residue, Lys36, was also found to contribute to the catalytic activity of the enzyme. Analysis of the C3larvinA homology model revealed that these three residues were participating in a series of interactions to properly orient both the Q-X-E and S-T-S motifs. Ala31 and Lys36 were found to associate with a structural network of residues previously identified in silico, whereas Asp23 forms novel interactions not previously described. At last, the membrane translocation activity into host target cells of each variant was assessed, highlighting a possible relationship between protein dipole and target cell entry.
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Rauh T, Brameyer S, Kielkowski P, Jung K, Sieber SA. MS-Based in Situ Proteomics Reveals AMPylation of Host Proteins during Bacterial Infection. ACS Infect Dis 2020; 6:3277-3289. [PMID: 33259205 PMCID: PMC9558369 DOI: 10.1021/acsinfecdis.0c00740] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
![]()
Bacteria utilize versatile strategies
to propagate infections within
human cells, e.g., by the injection of effector proteins,
which alter crucial signaling pathways. One class of such virulence-associated
proteins is involved in the AMPylation of eukaryotic Rho GTPases with
devastating effects on viability. In order to get an inventory of
AMPylated proteins, several technologies have been developed. However,
as they were designed for the analysis of cell lysates, knowledge
about AMPylation targets in living cells is largely lacking. Here,
we implement a chemical-proteomic method for deciphering AMPylated
host proteins in situ during bacterial infection.
HeLa cells treated with a previously established cell permeable pronucleotide
probe (pro-N6pA) were infected with Vibrio parahaemolyticus, and modified host proteins were identified upon probe enrichment
and LC-MS/MS analysis. Three already known targets of the AMPylator
VopS—Rac1, RhoA, and Cdc42—could be confirmed, and several
other Rho GTPases were additionally identified. These hits were validated
in comparative studies with V. parahaemolyticus wild type and a mutant producing an inactive VopS (H348A). The method
further allowed to decipher the sites of modification and facilitated
a time-dependent analysis of AMPylation during infection. Overall,
the methodology provides a reliable detection of host AMPylation in situ and thus a versatile tool in monitoring infection
processes.
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Affiliation(s)
- Theresa Rauh
- Department of Chemistry, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
| | - Sophie Brameyer
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany
| | - Pavel Kielkowski
- Department of Chemistry, Ludwig-Maximilians-Universität München, 81377 München, Germany
| | - Kirsten Jung
- Department of Biology I, Microbiology, Ludwig-Maximilians-Universität München, 82152 Martinsried, Germany
| | - Stephan A. Sieber
- Department of Chemistry, Chair of Organic Chemistry II, Center for Functional Protein Assemblies (CPA), Technische Universität München, Lichtenbergstraße 4, 85748 Garching, Germany
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ROCK and RHO Playlist for Preimplantation Development: Streaming to HIPPO Pathway and Apicobasal Polarity in the First Cell Differentiation. ADVANCES IN ANATOMY EMBRYOLOGY AND CELL BIOLOGY 2020; 229:47-68. [PMID: 29177764 DOI: 10.1007/978-3-319-63187-5_5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
In placental mammalian development, the first cell differentiation produces two distinct lineages that emerge according to their position within the embryo: the trophectoderm (TE, placenta precursor) differentiates in the surface, while the inner cell mass (ICM, fetal body precursor) forms inside. Here, we discuss how such position-dependent lineage specifications are regulated by the RHOA subfamily of small GTPases and RHO-associated coiled-coil kinases (ROCK). Recent studies in mouse show that activities of RHO/ROCK are required to promote TE differentiation and to concomitantly suppress ICM formation. RHO/ROCK operate through the HIPPO signaling pathway, whose cell position-specific modulation is central to establishing unique gene expression profiles that confer cell fate. In particular, activities of RHO/ROCK are essential in outside cells to promote nuclear localization of transcriptional co-activators YAP/TAZ, the downstream effectors of HIPPO signaling. Nuclear localization of YAP/TAZ depends on the formation of apicobasal polarity in outside cells, which requires activities of RHO/ROCK. We propose models of how RHO/ROCK regulate lineage specification and lay out challenges for future investigations to deepen our understanding of the roles of RHO/ROCK in preimplantation development. Finally, as RHO/ROCK may be inhibited by certain pharmacological agents, we discuss their potential impact on human preimplantation development in relation to fertility preservation in women.
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Ebeling J, Knispel H, Fünfhaus A, Genersch E. The biological role of the enigmatic C3larvinAB toxin of the honey bee pathogenic bacterium Paenibacillus larvae. Environ Microbiol 2019; 21:3091-3106. [PMID: 31187922 DOI: 10.1111/1462-2920.14709] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2019] [Revised: 06/03/2019] [Accepted: 06/09/2019] [Indexed: 11/30/2022]
Abstract
Paenibacillus larvae is the causative agent of the notifiable epizootic American foulbrood, a fatal bacterial disease of honey bee larvae. The species P. larvae has been classified into four differentially virulent and prevalent genotypes (ERIC I-IV), which also differ in their virulence factor equipment. Recently, a novel P. larvae toxin, the C3-like C3larvin, has been described. Genome analysis now revealed that the C3larvin gene is actually a part of a toxin locus encompassing two genes encoding a binary AB toxin with the A subunit being C3larvin (C3larvinA) and a putative B subunit (C3larvinB) encoded by the second gene. Sequence and structural analyses demonstrated that C3larvinB is a homologue of the Bacillus anthracis protective antigen (PA), the B subunit of anthrax toxin. The C3larvinAB toxin locus was interrupted by point mutations in all analysed P. larvae ERIC I and ERIC II strains. Only one P. larvae ERIC III/IV strain harboured an uninterrupted toxin locus comprising full-length genes for C3larvinA and B. Exposure bioassays did not substantiate a role as virulence factor for C3larvinAB in P. larvae ERIC I/II. However, the PA homologue C3larvinB had an influence on the virulence of the unique P. larvae strain expressing the functional C3larvinAB locus.
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Affiliation(s)
- Julia Ebeling
- Department of Molecular Microbiology and Bee Diseases, Institute for Bee Research, 16540, Hohen Neuendorf, Germany
| | - Henriette Knispel
- Department of Molecular Microbiology and Bee Diseases, Institute for Bee Research, 16540, Hohen Neuendorf, Germany
| | - Anne Fünfhaus
- Department of Molecular Microbiology and Bee Diseases, Institute for Bee Research, 16540, Hohen Neuendorf, Germany
| | - Elke Genersch
- Department of Molecular Microbiology and Bee Diseases, Institute for Bee Research, 16540, Hohen Neuendorf, Germany.,Freie Universität Berlin, Fachbereich Veterinärmedizin, Institut für Mikrobiologie und Tierseuchen, 14163, Berlin, Germany
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Abstract
ADP-ribosylation (ADPr) is an ancient reversible modification of cellular macromolecules controlling major biological processes as diverse as DNA damage repair, transcriptional regulation, intracellular transport, immune and stress responses, cell survival and proliferation. Furthermore, enzymatic reactions of ADPr are central in the pathogenesis of many human diseases, including infectious conditions. By providing a review of ADPr signalling in bacterial systems, we highlight the relevance of this chemical modification in the pathogenesis of human diseases depending on host-pathogen interactions. The post-antibiotic era has raised the need to find alternative approaches to antibiotic administration, as major pathogens becoming resistant to antibiotics. An in-depth understanding of ADPr reactions provides the rationale for designing novel antimicrobial strategies for treatment of infectious diseases. In addition, the understanding of mechanisms of ADPr by bacterial virulence factors offers important hints to improve our knowledge on cellular processes regulated by eukaryotic homologous enzymes, which are often involved in the pathogenesis of human diseases.
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Abstract
Bacterial pathogens developed several strategies to overcome defense systems of eukaryotic hosts. Within the infection process they need to attach to and cross through epithelial layers, escape from the innate and adaptive immune response, and find a physiological niche to survive. For this purpose bacteria developed toxins that specifically target central eukaryotic proteins, for example actin or Rho GTPases as regulators of the actin cytoskeleton. Some bacterial toxins catalyze a covalent modification of Rho GTPases to keep these molecular switches in a constitutive active or inactive state. This leads to rearrangement of the actin cytoskeleton. Toxin-treated cells show typical morphological changes depending on substrate specificity and action of the toxins. In this chapter I describe methods to illustrate how bacterial toxins may help to study the involvement of Rho GTPases in physiological and pathophysiological processes.
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Characterization of Pyrin Dephosphorylation and Inflammasome Activation in Macrophages as Triggered by the Yersinia Effectors YopE and YopT. Infect Immun 2019; 87:IAI.00822-18. [PMID: 30602502 DOI: 10.1128/iai.00822-18] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Accepted: 12/14/2018] [Indexed: 01/24/2023] Open
Abstract
Pathogenic Yersinia species deliver Yop effector proteins through a type III secretion system into host cells. Among these effectors, YopE and YopT are Rho-modifying toxins, which function to modulate host cell physiology and evade immune responses. YopE is a GTPase-activating protein (GAP) while YopT is a protease, and they inhibit RhoA by different modes of action. Modifications to RhoA are sensed by pyrin, which, once activated, assembles a caspase-1 inflammasome, which generates cytokines such as interleukin-1β (IL-1β) and cell death by pyroptosis. In Yersinia-infected macrophages, YopE or YopT triggers inflammasome assembly only in the absence of another effector, YopM, which counteracts pyrin by keeping it inactive. The glucosyltransferase TcdB from Clostridium difficile, a well-studied RhoA-inactivating toxin, triggers activation of murine pyrin by dephosphorylation of Ser205 and Ser241. To determine if YopE or YopT triggers pyrin dephosphorylation, we infected lipopolysaccharide (LPS)-primed murine macrophages with ΔyopM Yersinia pseudotuberculosis strains expressing wild-type (wt) or YopE mutant variants or YopT. By immunoblotting pyrin after infection, we observed that wt YopE triggered dephosphorylation of Ser205 and inflammasome activation. Pyrin dephosphorylation was reduced if a YopE variant had a defect in stability or RhoA specificity but not membrane localization. We also observed that wt YopT triggered pyrin dephosphorylation but more slowly than YopE, suggesting that YopE is dominant in this process. Our findings provide evidence that RhoA-modifying toxins trigger activation of pyrin by a conserved dephosphorylation mechanism. In addition, by characterization of YopE and YopT, we show that different features of effectors, such as RhoA specificity, affect the efficiency of pyrin dephosphorylation.
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Marikawa Y, Alarcon VB. RHOA activity in expanding blastocysts is essential to regulate HIPPO-YAP signaling and to maintain the trophectoderm-specific gene expression program in a ROCK/actin filament-independent manner. Mol Hum Reprod 2019; 25:43-60. [PMID: 30395288 PMCID: PMC6497036 DOI: 10.1093/molehr/gay048] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2018] [Accepted: 11/03/2018] [Indexed: 12/14/2022] Open
Abstract
STUDY QUESTION What molecular signals are required to maintain the functional trophectoderm (TE) during blastocyst expansion of the late stage of preimplantation development? SUMMARY ANSWER The activity of ras homology family member A (RHOA) GTPases is necessary to retain the expanded blastocyst cavity and also to sustain the gene expression program specific to TE. WHAT IS KNOWN ALREADY At the early stages of preimplantation development, the precursor of the TE lineage is generated through the molecular signals that integrate RHOA, RHO-associated coiled-coil containing protein kinase (ROCK), the apicobasal cell polarity, and the HIPPO-Yes-associated protein (YAP) signaling pathway. By contrast, molecular mechanisms regulating the maintenance of the TE characteristics at the later stage, which is crucial for blastocyst hatching and implantation, are scarcely understood. STUDY DESIGN, SIZE, DURATION Expanding mouse blastocysts, obtained from crosses of the F1 (C57BL6 × DBA/2) strain, were exposed to chemical agents that interfere with RHOA, ROCK, or the actin cytoskeleton for up to 8 h, and effects on the blastocyst cavity, HIPPO-YAP signaling, and cell lineage-specific gene expression profiles were examined. PARTICIPANTS/MATERIALS, SETTING, METHODS Mouse embryos at the embryonic stage E3.5 (expanding blastocysts) and E4.5 (fully expanded blastocysts) were treated with RHOA inhibitor (C3 exoenzyme), ROCK inhibitor (Y27632), or actin filament disruptors (cytochalasin B and latrunculin A). The integrity of the blastocyst cavity was evaluated based on the gross morphology. Effects on HIPPO-YAP signaling were assessed based on the presence of nuclearized YAP protein by immunofluorescence staining and the expression of YAP/TEA domain family member (TEAD) target genes by quantitative RT-PCR (qRT-PCR). The impact of these disruptors on cell lineages was evaluated based on expression of the TE-specific and inner cell mass-specific marker genes by qRT-PCR. The integrity of the apicobasal cell polarity was assessed by localization of protein kinase C zeta (PRKCZ; apical) and scribbled planar cell polarity (SCRIB; basal) proteins by immunofluorescence staining. For comparisons, cultured cell lines, NIH/3T3 (mouse fibroblast) and P19C5 (mouse embryonal carcinoma), were also treated with RHOA inhibitor, ROCK inhibitor, and actin filament disruptors for up to 8 h, and effects on HIPPO-YAP signaling were assessed based on expression of YAP/TEAD target genes by qRT-PCR. Each experiment was repeated using three independent batches of embryos (n = 40-80 per batch) or cell collections. Statistical analyses of data were performed, using one-way ANOVA and two-sample t-test. MAIN RESULTS AND THE ROLE OF CHANCE Inhibition of RHOA deflated the cavity, diminished nuclear YAP (P < 0.01), and down-regulated the YAP/TEAD target and TE-specific marker genes in both E3.5 and E4.5 blastocysts (P < 0.05), indicating that the maintenance of the key TE characteristics is dependent on RHOA activity. However, inhibition of ROCK or disruption of actin filament only deflated the blastocyst cavity, but did not alter HIPPO-YAP signaling or lineage-specific gene expressions, suggesting that the action of RHOA to sustain the TE-specific gene expression program is not mediated by ROCK or the actomyosin cytoskeleton. By contrast, ROCK inhibitor and actin filament disruptors diminished YAP/TEAD target gene expressions in cultured cells to a greater extent than RHOA inhibitor, implicating that the regulation of HIPPO-YAP signaling in expanding blastocysts is distinctly different from that in the cell lines. Furthermore, the apicobasal cell polarity proteins in the expanding blastocyst were mislocalized by ROCK inhibition but not by RHOA inhibition, indicating that cell polarity is not linked to regulation of HIPPO-YAP signaling. Taken together, our study suggests that RHOA activity is essential to maintain the TE lineage in the expanding blastocyst and it regulates HIPPO-YAP signaling and the lineage-specific gene expression program through mechanisms that are independent of ROCK or actomyosin cytoskeleton. LARGE-SCALE DATA Not applicable. LIMITATIONS, REASONS FOR CAUTION This study was conducted using one species, the mouse. Direct translation of the experiments and findings to human fertility preservation and ART requires further investigations. WIDER IMPLICATIONS OF THE FINDINGS The elucidation of the mechanisms of TE formation is highly pertinent to fertility preservation in women. Our findings may raise awareness among providers of ART that the TE is sensitive to disturbance even in the late stage of blastocyst expansion and that rational approaches should be devised to avoid conditions that may impair the TE and its function. STUDY FUNDING/COMPETING INTEREST(S) This study was funded by grants from the Ingeborg v.F. McKee Fund of the Hawaii Community Foundation (16ADVC-78882 to V.B.A.), and the National Institutes of Health (P20 GM103457 and R03 HD088839 to V.B.A.). The authors have no conflict of interest to declare.
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Affiliation(s)
- Yusuke Marikawa
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, USA
| | - Vernadeth B Alarcon
- Institute for Biogenesis Research, Department of Anatomy, Biochemistry and Physiology, John A. Burns School of Medicine, University of Hawaii at Manoa, Honolulu, HI, USA
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14
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Activated Rho GTPases in Cancer-The Beginning of a New Paradigm. Int J Mol Sci 2018; 19:ijms19123949. [PMID: 30544828 PMCID: PMC6321241 DOI: 10.3390/ijms19123949] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 11/30/2018] [Accepted: 12/05/2018] [Indexed: 12/26/2022] Open
Abstract
Involvement of Rho GTPases in cancer has been a matter of debate since the identification of the first members of this branch of the Ras superfamily of small GTPases. The Rho GTPases were ascribed important roles in the cell, although these were restricted to regulation of cytoskeletal dynamics, cell morphogenesis, and cell locomotion, with initially no clear indications of direct involvement in cancer progression. This paradigm has been challenged by numerous observations that Rho-regulated pathways are often dysregulated in cancers. More recently, identification of point mutants in the Rho GTPases Rac1, RhoA, and Cdc42 in human tumors has finally given rise to a new paradigm, and we can now state with confidence that Rho GTPases serve as oncogenes in several human cancers. This article provides an exposé of current knowledge of the roles of activated Rho GTPases in cancers.
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Popoff MR. Clostridium difficile and Clostridium sordellii toxins, proinflammatory versus anti-inflammatory response. Toxicon 2018; 149:54-64. [DOI: 10.1016/j.toxicon.2017.11.003] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2017] [Revised: 11/07/2017] [Accepted: 11/09/2017] [Indexed: 12/17/2022]
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Roxas JL, Monasky RC, Roxas BAP, Agellon AB, Mansoor A, Kaper JB, Vedantam G, Viswanathan V. Enteropathogenic Escherichia coli EspH-Mediated Rho GTPase Inhibition Results in Desmosomal Perturbations. Cell Mol Gastroenterol Hepatol 2018; 6:163-180. [PMID: 30003123 PMCID: PMC6039986 DOI: 10.1016/j.jcmgh.2018.04.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2017] [Accepted: 04/20/2018] [Indexed: 12/27/2022]
Abstract
BACKGROUND & AIMS The diarrheagenic pathogen, enteropathogenic Escherichia coli (EPEC), uses a type III secretion system to deliver effector molecules into intestinal epithelial cells (IECs). While exploring the basis for the lateral membrane separation of EPEC-infected IECs, we observed infection-induced loss of the desmosomal cadherin desmoglein-2 (DSG2). We sought to identify the molecule(s) involved in, and delineate the mechanisms and consequences of, EPEC-induced DSG2 loss. METHODS DSG2 abundance and localization was monitored via immunoblotting and immunofluorescence, respectively. Junctional perturbations were visualized by electron microscopy, and cell-cell adhesion was assessed using dispase assays. EspH alanine-scan mutants as well as pharmacologic agents were used to evaluate impacts on desmosomal alterations. EPEC-mediated DSG2 loss, and its impact on bacterial colonization in vivo, was assessed using a murine model. RESULTS The secreted virulence protein EspH mediates EPEC-induced DSG2 degradation, and contributes to desmosomal perturbation, loss of cell junction integrity, and barrier disruption in infected IECs. EspH sequesters Rho guanine nucleotide exchange factors and inhibits Rho guanosine triphosphatase signaling; EspH mutants impaired for Rho guanine nucleotide exchange factor interaction failed to inhibit RhoA or deplete DSG2. Cytotoxic necrotizing factor 1, which locks Rho guanosine triphosphatase in the active state, jasplakinolide, a molecule that promotes actin polymerization, and the lysosomal inhibitor bafilomycin A, respectively, rescued infected cells from EPEC-induced DSG2 loss. Wild-type EPEC, but not an espH-deficient strain, colonizes mouse intestines robustly, widens paracellular junctions, and induces DSG2 re-localization in vivo. CONCLUSIONS Our studies define the mechanism and consequences of EPEC-induced desmosomal alterations in IECs. These perturbations contribute to the colonization and virulence of EPEC, and likely related pathogens.
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Key Words
- A/E, attaching and effacing
- BSA, bovine serum albumin
- CM, calcium and magnesium
- DMEM, Dulbecco's modified Eagle medium
- DSC, desmocollin
- DSG, desmoglein
- DSG2
- Desmoglein
- EPEC
- EPEC, enteropathogenic Escherichia coli
- GEF, guanine nucleotide exchange factors
- GTPase, guanosine triphosphatase
- Host–Pathogen Interaction
- IEC, intestinal epithelial cell
- IF, intermediate filament
- PBS, phosphate-buffered saline
- T3SS, type 3 secretion system
- TER, transepithelial electrical resistance
- TJ, tight junction
- WT, wild-type
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Affiliation(s)
- Jennifer Lising Roxas
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Ross Calvin Monasky
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Bryan Angelo P. Roxas
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - Al B. Agellon
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
- BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona
| | - Asad Mansoor
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
| | - James B. Kaper
- University of Maryland School of Medicine, Baltimore, Maryland
| | - Gayatri Vedantam
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
- BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona
- Department of Immunobiology, University of Arizona, Tucson, Arizona
- Southern Arizona VA Healthcare System, Tucson, Arizona
| | - V.K. Viswanathan
- School of Animal and Comparative Biomedical Sciences, University of Arizona, Tucson, Arizona
- BIO5 Institute for Collaborative Research, University of Arizona, Tucson, Arizona
- Department of Immunobiology, University of Arizona, Tucson, Arizona
- Correspondence Address correspondence to: V. K. Viswanathan, PhD, School of Animal and Comparative Biomedical Sciences, 1006 E. Lowell, Building 106, Room 231, University of Arizona, Tucson, Arizona 85721. fax: (520) 621-6366.
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Ebeling J, Fünfhaus A, Knispel H, Krska D, Ravulapalli R, Heney KA, Lugo MR, Merrill AR, Genersch E. Characterization of the toxin Plx2A, a RhoA-targeting ADP-ribosyltransferase produced by the honey bee pathogenPaenibacillus larvae. Environ Microbiol 2017; 19:5100-5116. [DOI: 10.1111/1462-2920.13989] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2017] [Revised: 10/24/2017] [Accepted: 11/04/2017] [Indexed: 12/19/2022]
Affiliation(s)
- Julia Ebeling
- Department of Molecular Microbiology and Bee Diseases; Institute for Bee Research; 16540 Hohen Neuendorf Germany
| | - Anne Fünfhaus
- Department of Molecular Microbiology and Bee Diseases; Institute for Bee Research; 16540 Hohen Neuendorf Germany
| | - Henriette Knispel
- Department of Molecular Microbiology and Bee Diseases; Institute for Bee Research; 16540 Hohen Neuendorf Germany
| | - Daniel Krska
- Department of Molecular and Cellular Biology; Guelph ON Canada N1G 2W1
| | | | - Kayla A. Heney
- Department of Molecular and Cellular Biology; Guelph ON Canada N1G 2W1
| | - Miguel R. Lugo
- Department of Molecular and Cellular Biology; Guelph ON Canada N1G 2W1
| | - A. Rod Merrill
- Department of Molecular and Cellular Biology; Guelph ON Canada N1G 2W1
| | - Elke Genersch
- Department of Molecular Microbiology and Bee Diseases; Institute for Bee Research; 16540 Hohen Neuendorf Germany
- Fachbereich Veterinärmedizin, Institut für Mikrobiologie und Tierseuchen; Freie Universität Berlin; 14163 Berlin Germany
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Ray A, Schwartz N, de Souza Santos M, Zhang J, Orth K, Salomon D. Type VI secretion system MIX-effectors carry both antibacterial and anti-eukaryotic activities. EMBO Rep 2017; 18:1978-1990. [PMID: 28912123 PMCID: PMC5666596 DOI: 10.15252/embr.201744226] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 08/14/2017] [Accepted: 08/16/2017] [Indexed: 12/12/2022] Open
Abstract
Most type VI secretion systems (T6SSs) described to date are protein delivery apparatuses that mediate bactericidal activities. Several T6SSs were also reported to mediate virulence activities, although only few anti-eukaryotic effectors have been described. Here, we identify three T6SSs in the marine bacterium Vibrio proteolyticus and show that T6SS1 mediates bactericidal activities under warm marine-like conditions. Using comparative proteomics, we find nine potential T6SS1 effectors, five of which belong to the polymorphic MIX-effector class. Remarkably, in addition to six predicted bactericidal effectors, the T6SS1 secretome includes three putative anti-eukaryotic effectors. One of these is a MIX-effector containing a cytotoxic necrotizing factor 1 domain. We demonstrate that T6SS1 can use this MIX-effector to target phagocytic cells, resulting in morphological changes and actin cytoskeleton rearrangements. In conclusion, the V. proteolyticus T6SS1, a system homologous to one found in pathogenic vibrios, uses a suite of polymorphic effectors that target both bacteria and eukaryotic neighbors.
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Affiliation(s)
- Ann Ray
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Nika Schwartz
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Marcela de Souza Santos
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Junmei Zhang
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Kim Orth
- Department of Molecular Biology, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Howard Hughes Medical Institute, University of Texas Southwestern Medical Center, Dallas, TX, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Dor Salomon
- Department of Clinical Microbiology and Immunology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
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Bremer E. Clostridium difficile: A bad bug goes into defensive mode. Environ Microbiol 2017; 19:2523-2528. [PMID: 28447375 DOI: 10.1111/1462-2920.13776] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 04/19/2017] [Indexed: 11/26/2022]
Affiliation(s)
- Erhard Bremer
- Laboratory for Microbiology, Department of Biology, Philipps-University Marburg, Karl-von Frisch Str. 8, Marburg, D-35043, Germany.,LOEWE Center for Synthetic Microbiology, Philipps-University Marburg, Hans-Meerwein Str. 6, Marburg, D-35043, Germany
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Harms A, Stanger FV, Dehio C. Biological Diversity and Molecular Plasticity of FIC Domain Proteins. Annu Rev Microbiol 2016; 70:341-60. [PMID: 27482742 DOI: 10.1146/annurev-micro-102215-095245] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The ubiquitous proteins with FIC (filamentation induced by cyclic AMP) domains use a conserved enzymatic machinery to modulate the activity of various target proteins by posttranslational modification, typically AMPylation. Following intensive study of the general properties of FIC domain catalysis, diverse molecular activities and biological functions of these remarkably versatile proteins are now being revealed. Here, we review the biological diversity of FIC domain proteins and summarize the underlying structure-function relationships. The original and most abundant genuine bacterial FIC domain proteins are toxins that use diverse molecular activities to interfere with bacterial physiology in various, yet ill-defined, biological contexts. Host-targeted virulence factors have evolved repeatedly out of this pool by exaptation of the enzymatic FIC domain machinery for the manipulation of host cell signaling in favor of bacterial pathogens. The single human FIC domain protein HypE (FICD) has a specific function in the regulation of protein stress responses.
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Affiliation(s)
- Alexander Harms
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; , ,
| | - Frédéric V Stanger
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; , , .,Focal Area Structural Biology and Biophysics, Biozentrum, University of Basel, CH-4056 Basel, Switzerland.,*Current address: Department of Biophysics and Biophysical Chemistry, Johns Hopkins University School of Medicine, Baltimore, MD 21205
| | - Christoph Dehio
- Focal Area Infection Biology, Biozentrum, University of Basel, CH-4056 Basel, Switzerland; , ,
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Abstract
The virulence of highly pathogenic bacteria such as Salmonella, Yersinia, Staphylococci, Clostridia, and pathogenic strains of Escherichia coli involves intimate cross-talks with the host actin cytoskeleton and its upstream regulators. A large number of virulence factors expressed by these pathogens modulate Rho GTPase activities either by mimicking cellular regulators or by catalyzing posttranslational modifications of these small proteins. This impressive convergence of virulence toward Rho GTPases and actin indeed offers pathogens the capacity to breach host defenses and invade their host, while it promotes inflammatory reactions. In return, the study of this targeting of Rho GTPases in infection has been an invaluable source of information in cell signaling, cell biology, and biomechanics, as well as in immunology. Through selected examples, I highlight the importance of recent studies on this crosstalk, which have unveiled new mechanisms of regulation of Rho GTPases; the relationship between cell shape and actin cytoskeleton organization; and the relationship between Rho GTPases and innate immune signaling.
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Affiliation(s)
- Emmanuel Lemichez
- UCA, Inserm, C3M, U1065, Team Microbial Toxins in Host Pathogen Interactions, Equipe Labellisée la Ligue Contre le Cancer, Nice, 06204, France.
- UFR Médecine, Université de Nice-Sophia-Antipolis, Nice, France.
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