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Yoo SK, Pascoe HG, Pereira T, Kondo S, Jacinto A, Zhang X, Hariharan IK. Plexins function in epithelial repair in both Drosophila and zebrafish. Nat Commun 2016; 7:12282. [PMID: 27452696 PMCID: PMC4962468 DOI: 10.1038/ncomms12282] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Accepted: 06/17/2016] [Indexed: 12/20/2022] Open
Abstract
In most multicellular organisms, homeostasis is contingent upon maintaining epithelial integrity. When unanticipated insults breach epithelial barriers, dormant programmes of tissue repair are immediately activated. However, many of the mechanisms that repair damaged epithelia remain poorly characterized. Here we describe a role for Plexin A (PlexA), a protein with particularly well-characterized roles in axonal pathfinding, in the healing of damaged epithelia in Drosophila. Semaphorins, which are PlexA ligands, also regulate tissue repair. We show that Drosophila PlexA has GAP activity for the Rap1 GTPase, which is known to regulate the stability of adherens junctions. Our observations suggest that the inhibition of Rap1 activity by PlexA in damaged Drosophila epithelia allows epithelial remodelling, thus facilitating wound repair. We also demonstrate a role for Plexin A1, a zebrafish orthologue of Drosophila PlexA, in epithelial repair in zebrafish tail fins. Thus, plexins function in epithelial wound healing in diverse taxa. Plexins are semaphorin receptors and are well known for their roles in neuronal pathfinding. Here the authors describe a role for Plexin A in healing damaged epithelia in Drosophila and zebrafish. In Drosophila, Plexin A inhibits the GTPase Rap1 to allow epithelial remodelling to facilitate wound repair.
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Affiliation(s)
- Sa Kan Yoo
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA.,The Miller Institute, University of California, Berkeley, California 94720, USA.,Physiological Genetics Laboratory, RIKEN, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe 650-0047, Japan
| | - Heath G Pascoe
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Telmo Pereira
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, 1649-028 Lisboa, Portugal.,CEDOC, Chronic Diseases Research Centre, NOVA Medical School, Universidade NOVA de Lisboa, 130, 1169-056 Lisboa, Portugal
| | - Shu Kondo
- Genetic Strains Research Center, National Institute of Genetics, 1111 Yata, Mishima, Shizuoka 411-8540, Japan
| | - Antonio Jacinto
- CEDOC, Chronic Diseases Research Centre, NOVA Medical School, Universidade NOVA de Lisboa, 130, 1169-056 Lisboa, Portugal
| | - Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, Texas 75390, USA
| | - Iswar K Hariharan
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, USA
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Abstract
Signaling through plexin, the major cell surface receptor for semaphorin, plays critical roles in regulating processes such as neuronal axon guidance, angiogenesis and immune response. Plexin is normally kept inactive in the absence of semaphorin. Upon binding of semaphorin to the extracellular region, plexin is activated and transduces signal to the inside of the cell through its cytoplasmic region. The GTPase Activating Protein (GAP) domain in the plexin cytoplasmic region mediates the major intracellular signaling pathway. The substrate specificity and regulation mechanisms of the GAP domain have only been revealed recently. Many intracellular proteins serve as either upstream regulators or downstream transducers by directly interacting with plexin. The mechanisms of action for some of these proteins also start to emerge from recent studies. We review here these advances in the mechanistic understanding of plexin intracellular signaling from a structural perspective.
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Affiliation(s)
- Heath G Pascoe
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Yuxiao Wang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xuewu Zhang
- Department of Pharmacology, University of Texas Southwestern Medical Center, Dallas, TX, USA; Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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Wang Y, Pascoe HG, Brautigam CA, He H, Zhang X. Structural basis for activation and non-canonical catalysis of the Rap GTPase activating protein domain of plexin. eLife 2013; 2:e01279. [PMID: 24137545 PMCID: PMC3787391 DOI: 10.7554/elife.01279] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2013] [Accepted: 08/22/2013] [Indexed: 12/14/2022] Open
Abstract
Plexins are cell surface receptors that bind semaphorins and transduce signals for regulating neuronal axon guidance and other processes. Plexin signaling depends on their cytoplasmic GTPase activating protein (GAP) domain, which specifically inactivates the Ras homolog Rap through an ill-defined non-canonical catalytic mechanism. The plexin GAP is activated by semaphorin-induced dimerization, the structural basis for which remained unknown. Here we present the crystal structures of the active dimer of zebrafish PlexinC1 cytoplasmic region in the apo state and in complex with Rap. The structures show that the dimerization induces a large-scale conformational change in plexin, which opens the GAP active site to allow Rap binding. Plexin stabilizes the switch II region of Rap in an unprecedented conformation, bringing Gln63 in Rap into the active site for catalyzing GTP hydrolysis. The structures also explain the unique Rap-specificity of plexins. Mutational analyses support that these mechanisms underlie plexin activation and signaling. DOI:http://dx.doi.org/10.7554/eLife.01279.001.
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Affiliation(s)
- Yuxiao Wang
- Department of Pharmacology , University of Texas Southwestern Medical Center , Dallas , United States
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