Focal adhesion kinase, RhoA, and p38 mitogen-activated protein kinase modulates apoptosis mediated by angiotensin II...

Apoptosis plays an important role in cellular processes such as development, differentiation, and homeostasis. Although the participation of angiotensin II (Ang II) AT2 receptors (AT 2 R) in cellular apoptosis is well accepted, the signaling pathway involved in this process is not well established. We evaluated the participation of signaling proteins focal adhesion kinase (FAK), RhoA, and p38 mitogen-activated protein kinase (p38MAPK) in apoptosis induced by Ang II via AT 2 R overexpressed in HeLa cells. Following a short stimulation time (120 to 240 minutes) with Ang II, HeLa-AT 2 cells showed nuclear condensation, stress fibers disassembly and membrane blebbing. FAK, classically involved in cytoskeleton reorganization, has been postulated as an early marker of cellular apoptosis. Thus, we evaluated FAK cleavage, detected at early stimulation times (15 to 30 minutes). Apoptosis was confirmed by increased caspase-3 cleavage and enzymatic activity of caspase-3/7. Participation of RhoA was evaluated. HeLa-AT 2 cells overexpressing RhoA wild-type (WT) or their mutants, RhoA V14 (constitutively active form) or RhoA N19 (dominant-negative form) were used to explore RhoA participation. HeLa-AT 2 cells expressing the constitutively active variant RhoA V14 showed enhanced apoptotic features at earlier times as compared with cells expressing the WT variant. RhoA N19 expression prevented nuclear condensation/caspase activation. Inhibition of p38MAPK caused an increase in nuclear condensation and caspase-3/7 activation, suggesting a protective role of p38MAPK. Our results clearly demonstrated that stimulation of AT 2 R induce apoptosis with participation of FAK and RhoA while p38MAPK seems to play a prosurvival role.