In vivodissection of Rhoa function in vascular development using zebrafish

Abstract

ABSTRACTRationaleThe small monomeric GTPase RHOA acts as a master regulator of signal transduction cascades by activating effectors of cellular signaling, including the Rho-associated protein kinases ROCK1/2. Previousin vitrocell culture studies suggest that RHOA can regulate many critical aspects of vascular endothelial cell (EC) biology, including focal adhesion, stress fiber formation, and angiogenesis. However, the specificin vivoroles of RHOA during vascular development and homeostasis are still not well understood.ObjectiveIn this study we examine thein vivofunctions of RHOA in regulating vascular development and integrity in zebrafish.Methods and ResultsWe use zebrafish RHOA-ortholog (rhoaa) mutants, transgenic embryos expressing wild type, dominant-negative, or constitutively active forms ofrhoaain ECs, and a pharmacologic inhibitor of ROCK1/2 to study thein vivoconsequences of RHOA gain- and loss-of-function in the vascular endothelium. Our findings document roles for RHOA in vascular integrity, developmental angiogenesis, and vascular morphogenesis.ConclusionsOur results indicate that either too much or too little RHOA activity leads to vascular dysfunctionin vivo.