[Pathophysiology of the renin-angiotensin system]

Angiotensin II is a potent vasoconstrictor as well as a growth stimulator. Angiotensin type 1 (AT1) and type 2 (AT2) receptors have been cloned, and molecular mechanisms by which angiotensin II stimulates cell growth have been also clarified by molecular biological techniques including gene targeting and transgenic animals. AT1 promotes hypertrophy and hyperplasia through G protein-associated pathway and G-protein-independent pathway consisted of tyrosine kinase, JAK/STAT, and growth hormone signal transduction. Function of AT2 is not fully understood, but recently has been reported to reverse the effect of AT1. This is a brief review on angiotensin II functions and its signal transduction, including the aspect of the constitutively active AT1 mutant receptor.