Phospholipase Cγ Activation Drives Increased Production of Autotaxin in Endothelial Cells and Lysophosphatidic Acid-Dependent Regression

We previously reported that vascular endothelial growth factor (VEGF)-dependent activation of phospholipase C gamma 1 (PLC gamma) regulated tube stability by competing with phosphoinositide 3-kinase (PI3K) for their common substrate. Here we describe an additional mechanism by which PLC gamma promoted regression of tubes and blood vessels. Namely, it increased the level of autotaxin (ATX), which is a secreted form of lysophospholipase D that produces lysophosphatidic acid (LPA). LPA promoted motility of endothelial cells, leading to disorganization/regression of tubes in vitro. Furthermore, mice that under-or overexpressed members of this intrinsic destabilization pathway showed either delayed or accelerated, respectively, regression of blood vessels. We conclude that endothelial cells can be instructed to engage a PLC gamma-dependent intrinsic destabilization pathway that results in the production of soluble regression factors such as ATX and LPA. These findings are likely to potentiate ongoing efforts to prevent, manage, and eradicate numerous angiogenesis-based diseases such as proliferative diabetic retinopathy and solid tumors.