Figure 2. JAK2 is a key player in the renin-angiotensin-aldosterone autoregulation. Angiotensin II, produced from angiotensin I by the angiotensin converting enzyme (ACE), stimulates the production of aldosterone by inducing the rate-limiting steroidogenic acute regulatory protein (StAR). Aldosterone stimulates ACE expression through a JAK2-dependent mechanism. Furthermore, angiotensin II induces phosphorylation and activation of JAK2 which then activates StAR expression. This indicates the presence of a positive autoregulatory loop in the renin-angiotensin-aldosterone system where JAK2 seems to play an integral role.