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Van den Broeke C, Jacob T, Favoreel HW. Rho'ing in and out of cells: viral interactions with Rho GTPase signaling. Small GTPases 2014; 5:e28318. [PMID: 24691164 DOI: 10.4161/sgtp.28318] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Rho GTPases are key regulators of actin and microtubule dynamics and organization. Increasing evidence shows that many viruses have evolved diverse interactions with Rho GTPase signaling and manipulate them for their own benefit. In this review, we discuss how Rho GTPase signaling interferes with many steps in the viral replication cycle, especially entry, replication, and spread. Seen the diversity between viruses, it is not surprising that there is considerable variability in viral interactions with Rho GTPase signaling. However, several largely common effects on Rho GTPases and actin architecture and microtubule dynamics have been reported. For some of these processes, the molecular signaling and biological consequences are well documented while for others we just begin to understand them. A better knowledge and identification of common threads in the different viral interactions with Rho GTPase signaling and their ultimate consequences for virus and host may pave the way toward the development of new antiviral drugs that may target different viruses.
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Affiliation(s)
- Céline Van den Broeke
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
| | - Thary Jacob
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
| | - Herman W Favoreel
- Department of Virology, Parasitology, and Immunology; Faculty of Veterinary Medicine; Ghent University; Ghent, Belgium
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152
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Requirements for and consequences of Rac-dependent protrusion. Eur J Cell Biol 2014; 93:184-93. [PMID: 24629839 DOI: 10.1016/j.ejcb.2014.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2013] [Revised: 01/29/2014] [Accepted: 01/30/2014] [Indexed: 01/17/2023] Open
Abstract
Small GTPases of the Rac subfamily exert multiple functions, the most prominent of which includes stimulation of dynamic actin rearrangements at the cell periphery. Frequently, these actin reorganizations cause the protrusion of leaflets of plasma membrane, so-called lamellipodia, which remain anchored at flat surfaces during forward protrusion of migrating cells, or develop into ruffles when lifting up- and backwards. Ruffling membranes are also engaged in fluid and particle uptake during pino- and phagocytosis, respectively. In recent work, we sought to clarify the precise role of Rac GTPases in actin-based protrusion, using a gene disruption approach. Furthermore, we aimed at dissecting the function of its downstream target Arp2/3 complex employing its instantaneous inhibition during simultaneous Rac activation. These complementary approaches allow comparison of the consequences of Rac versus Arp2/3 complex loss of function at the cell periphery, and help to formulate a working hypothesis for how the actin network in lamellipodia is initiated and maintained.
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153
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Humphries AC, Donnelly SK, Way M. Cdc42 and the Rho GEF intersectin-1 collaborate with Nck to promote N-WASP-dependent actin polymerisation. J Cell Sci 2014; 127:673-85. [PMID: 24284073 DOI: 10.1242/jcs.141366] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Vaccinia virus enhances its cell-to-cell spread by inducing Arp2/3-dependent actin polymerisation. This process is initiated by Src- and Abl-mediated phosphorylation of the viral transmembrane protein A36, leading to recruitment of a signalling network consisting of Grb2, Nck, WIP and N-WASP. Nck is a potent activator of N-WASP-Arp2/3-dependent actin polymerisation. However, recent observations demonstrate that an interaction between Nck and N-WASP is not required for vaccinia actin tail formation. We found that Cdc42 cooperates with Nck to promote actin tail formation by stabilising N-WASP beneath the virus. Cdc42 activation is mediated by the Rho guanine-nucleotide-exchange factor (GEF) intersectin-1 (ITSN1), which is recruited to the virus prior to its actin-based motility. Moreover, Cdc42, ITSN1 and N-WASP function collaboratively in a feed-forward loop to promote vaccinia-induced actin polymerisation. Outside the context of infection, we demonstrate that ITSN1 also functions together with Cdc42, Nck and N-WASP during phagocytosis mediated by the Fc gamma receptor. Our observations suggest that ITSN1 is an important general regulator of Cdc42-, Nck- and N-WASP-dependent actin polymerisation.
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Affiliation(s)
- Ashley C Humphries
- Cell Motility Laboratory, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London WC2A 3LY, UK
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154
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Travier L, Lecuit M. Listeria monocytogenes ActA: a new function for a 'classic' virulence factor. Curr Opin Microbiol 2013; 17:53-60. [PMID: 24581693 DOI: 10.1016/j.mib.2013.11.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Revised: 11/23/2013] [Accepted: 11/27/2013] [Indexed: 10/25/2022]
Abstract
Listeria monocytogenes (Lm) is ubiquitous and widespread in the environment. It is responsible for one of the most severe human foodborne infection. Lm is a facultative intracellular bacterium that can cross the intestinal barrier, disseminate via the bloodstream and reach the liver, spleen, central nervous system and fetus. The bacterial surface protein ActA is one of the most critical and best characterized virulence factors of Lm. It fulfills many essential functions within host cells, allowing Lm escape from autophagy and recruiting an actin polymerization complex that promotes Lm actin-based motility, cell-to-cell spread and dissemination within host tissues. We have recently shown that ActA also acts extracellularly. It mediates Lm aggregation and biofilm formation in vitro and in vivo, and long-term colonization of the gut lumen. This new property of ActA favors Lm transmission and may participate in the selective pressure on Lm to maintain ActA.
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Affiliation(s)
- Laetitia Travier
- Institut Pasteur, Biology of Infection Unit, 75015 Paris, France; Inserm U1117, Paris, France
| | - Marc Lecuit
- Institut Pasteur, Biology of Infection Unit, 75015 Paris, France; Inserm U1117, Paris, France; French National Reference Center and WHO Collaborating Centre Listeria, Institut Pasteur, Paris, France; Paris Descartes University, Sorbonne Paris Cité, Necker-Pasteur for Infectiology, Institut Imagine, Necker-Enfants Malades University Hospital, Paris, France.
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155
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Reed SCO, Lamason RL, Risca VI, Abernathy E, Welch MD. Rickettsia actin-based motility occurs in distinct phases mediated by different actin nucleators. Curr Biol 2013; 24:98-103. [PMID: 24361066 DOI: 10.1016/j.cub.2013.11.025] [Citation(s) in RCA: 83] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 10/21/2013] [Accepted: 11/12/2013] [Indexed: 11/16/2022]
Abstract
Many intracellular bacterial pathogens undergo actin-based motility to promote cell-cell spread during infection [1]. For each pathogen, motility was assumed to be driven by a single actin polymerization pathway. Curiously, spotted fever group Rickettsia differ from other pathogens in possessing two actin-polymerizing proteins. RickA, an activator of the host Arp2/3 complex, was initially proposed to drive motility [2, 3]. Sca2, a mimic of host formins [4, 5], was later shown to be required for motility [6]. Whether and how their activities are coordinated has remained unclear. Here, we show that each protein directs an independent mode of Rickettsia parkeri motility at different times during infection. Early after invasion, motility is slow and meandering, generating short, curved actin tails that are enriched with Arp2/3 complex and cofilin. Early motility requires RickA and Arp2/3 complex and is correlated with transient RickA localization to the bacterial pole. Later in infection, motility is faster and directionally persistent, resulting in long, straight actin tails. Late motility is independent of Arp2/3 complex and RickA and requires Sca2, which accumulates at the bacterial pole. Both motility pathways facilitate cell-to-cell spread. The ability to exploit two actin assembly pathways may allow Rickettsia to establish an intracellular niche and spread between diverse cells throughout a prolonged infection.
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Affiliation(s)
- Shawna C O Reed
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Microbiology Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Rebecca L Lamason
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Viviana I Risca
- Biophysics Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Emma Abernathy
- Microbiology Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Matthew D Welch
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; Microbiology Graduate Group, University of California, Berkeley, Berkeley, CA 94720, USA.
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