| First Author | Guo X | Year | 2020 |
| Journal | PLoS One | Volume | 15 |
| Issue | 4 | Pages | e0231739 |
| PubMed ID | 32352989 | Mgi Jnum | J:288300 |
| Mgi Id | MGI:6423182 | Doi | 10.1371/journal.pone.0231739 |
| Citation | Guo X, et al. (2020) Focal adhesion kinase and Src mediate microvascular hyperpermeability caused by fibrinogen- gammaC- terminal fragments. PLoS One 15(4):e0231739 |
| abstractText | OBJECTIVES: We previously reported microvascular leakage resulting from fibrinogen-gamma chain C-terminal products (gammaC) occurred via a RhoA-dependent mechanism. The objective of this study was to further elucidate the signaling mechanism by which gammaC induces endothelial hyperpermeability. Since it is known that gammaC binds and activates endothelial alphavbeta3, a transmembrane integrin receptor involved in intracellular signaling mediated by the tyrosine kinases FAK and Src, we hypothesized that gammaC alters endothelial barrier function by activating the FAK-Src pathway leading to junction dissociation and RhoA driven cytoskeletal stress-fiber formation. METHODS AND RESULTS: Using intravital microscopy of rat mesenteric microvessels, we show increased extravasation of plasma protein (albumin) resulting from gammaC administration. In addition, capillary fluid filtration coefficient (Kfc) indicated gammaC-induced elevated lung vascular permeability. Furthermore, gammaC decreased transendothelial barrier resistance in a time-dependent and dose-related fashion in cultured rat lung microvascular endothelial cells (RLMVECs), accompanied by increased FAK/Src phosphorylation detection by western blot. Experiments with pharmacological inhibition or gene silencing of FAK showed significantly reduced gammaC-induced albumin and fluid leakage across microvessels, stress-fiber formation, VE-cadherin tyrosine phosphorylation, and improved gammaC-induced endothelial barrier dysfunction, indicating the involvement of FAK in gammaC mediated hyperpermeability. Comparable results were found when Src was targeted in a similar manner, however inhibition of FAK prevented Src activation, suggesting that FAK is upstream of Src in gammaC-mediated hyperpermeability. In addition, gammaC-induced cytoskeletal stress-fiber formation was attenuated during inhibition or silencing of these tyrosine kinases, concomitantly with RhoA inhibition. CONCLUSION: The FAK-Src pathway contributes to gammaC-induced microvascular barrier dysfunction, junction protein phosphorylation and disorganization in a manner that involves RhoA and stress-fiber formation. |
