GSE182806
Systematic variation of RhoA activity reveals an inhibitory impact of active RhoA on the homeostasis and angiogenic capacity of human endothelial cells
The small GTPase RhoA regulates a variety of cellular processes, including cell motility, proliferation, survival and permeability. In addition, there are reports suggesting that the RhoA-ROCK axis plays a role in VEGF-mediated angiogenesis, whereas other work has shown opposite effects. To elucidate this conflicting data, we examined HUVEC and HCAEC after stable overexpression (lentiviral transduction) of constitutively active (G14V/Q63L), dominant-negative (T19N), or wild-type RhoA using a variety of in vitro angiogenesis assays (proliferation, migration, tube formation, angiogenic sprouting, endothelial cell viability) and a HUVEC xenograft assay in immune incompetent NSGTM mice in vivo. We observed that expression of active as well as wild-type RhoA but not expression of dominant-negative RhoA significantly increased endothelial cell death as well as inhibited endothelial cell proliferation, migration, tube formation and angiogenic sprouting of endothelial cells in vitro and reduced HUVEC-related angiogenesis in vivo. Inhibition of RhoA by C3 transferase antagonized inhibitory RhoA effects and strongly enhanced VEGF-induced angiogenic sprouting in control-treated cells. In contrast, inhibition of RhoA effectors ROCK1/2 and LIMK1/2 had no significant effect  on RhoA-related effects, but again increased angiogenic sprouting and migration of control-treated cells. In line with these data, VEGF did not activate RhoA in HUVEC as measured by a FRET-based biosensor. Furthermore, global transcriptome and subsequent bioinformatic gene ontology (GO) enrichment analyses revealed that constitutively active RhoA induces a differentially expressed gene pattern that is enriched for GO biological process terms such as mitotic nuclear division, cell proliferation, cell motility and cell adhesion and includes a significant decrease in VEGFR-2 and NOS3 expression. Thus, our data demonstrate that increased RhoA activity has the potential to trigger endothelial dysfunction and anti-angiogenic effects independently of its well-characterized downstream effectors ROCK and LIMK. Overall design: Three biological replicates were analyzed for each of three different conditions (overexpression of constitutively active RhoA (Q63L) and dominant negative RhoA (T19N) compared to control without overexpression of RhoA).