Revisiting the relationship between (Pro)Renin receptor and the intrarenal RAS: focus on the soluble receptor

PURPOSE OF REVIEW: The (pro)renin receptor (PRR), also termed as ATPase H+ transporting accessory protein 2 (ATP6AP2), was originally cloned as a specific receptor for prorenin and renin [together called (pro)renin]. Given the wide tissue distribution of PRR, PRR was further postulated to act as a regulator of tissue renin. However, assigning a physiological role of PRR within the renin-angiotensin system (RAS) has been challenging largely due to its pleotropic functions in regulation of embryogenesis, autophagy, and H+ transport. The current review will summarize recent advances in understanding the roles of sPPR within the intrarenal RAS as well as those outside this local system. RECENT FINDINGS: Site-1 protease (S1P) is a predominant source of sPPR at least in the kidney. So far most of the known physiological functions of PRR including renal handling of electrolytes and fluid and blood pressure are mediated by sPRR. In particular, sPRR serves as a positive regulator of collecting duct renin to activate the intrarenal RAS during water deprivation or angiotensin-II (AngII) infusion. However, PRR/sPRR can act in renin-independent manner under other circumstances. SUMMARY: S1P-derived sPRR has emerged as a key regulator of kidney function and blood pressure and its relationship with the intrarenal RAS depends on the physiological context.