An endothelial cell genetic screen identifies the GTPase Rem2 as a suppressor of p19^ARF expression that promotes endothelial cell proliferation and angiogenesis

Angiogenesis requires an increase in endothelial cell proliferation to support an increase in mass of blood vessels. We designed an in vitro endothelial cell model to functionally screen for genes that regulate endothelial cell proliferation. A gain of function screen for genes that bypass p53 endothelial cell arrest identified Rem2, a Ras-like GTPase. We show that ectopic Rem2 suppresses p14^ARF (human) or p19^ARF (mouse) expression that leads to increased endothelial cell proliferation. Conversely, loss of ectopic Rem2 by RNA interference restores p19^ARF expression in endothelial cells. We further show that Rem2-interacting 14-3-3 proteins are involved in the cell localization of Rem2, regulation of p19^ARF expression, and endothelial cell proliferation. Finally, we demonstrate using the RIP1 tag2 mouse model of pancreatic disease that Rem2 is up-regulated in endothelial cells of stage IV disease. The data unravel a possible molecular mechanism for Rem2-induced angiogenesis and suggests Rem2 as a potential novel target for treating pathological angiogenesis.