Activation of ENaC in collecting duct cells by prorenin and its receptor PRR: involvement of Nox4-derived hydrogen peroxide

Abstract

The collecting duct (CD) has been recognized as an important source of prorenin/renin, and it also expresses (pro)renin receptor (PRR). The goal of this study was to examine the hypothesis that prorenin or renin via PRR regulates epithelial Na(+) channel (ENaC) activity in mpkCCD cells. Transepithelial Na(+) transport was measured by using a conventional epithelial volt-ohmmeter and was expressed as the calculated equivalent current (Ieq). Amiloride-inhibitable Ieq was used as a reflection of ENaC activity. Administration of prorenin in the nanomolar range induced a significant increase in Ieq that was detectable as early as 1 min, peaked at 5 min, and gradually returned to baseline within 15 min. These changes in Ieq were completely prevented by a newly developed PRR decoy inhibitor, PRO20. Prorenin-induced Ieq was inhibitable by amiloride. Compared with prorenin, renin was less effective in stimulating Ieq Prorenin-induced Ieq was attenuated by apocynin but enhanced by tempol, the latter effect being prevented by catalase. In response to prorenin treatment, the levels of total reactive oxygen species and H2O2 were both increased, as detected by spin-trap analysis and reactive oxygen species (ROS)-Glo H2O2 assay, respectively. Both siRNA-mediated Nox4 knockdown and the dual Nox1/4 inhibitor GKT137892 attenuated prorenin-induced Ieq Overall, our results demonstrate that activation of PRR by prorenin stimulates ENaC activity in CD cells via Nox4-derived H2O2.

Soluble (pro)renin receptor via β-catenin enhances urine concentration capability as a target of liver X receptor

“…In support of this possibility, an antibody against the epitope in the sPRR, anti-PRR-N antibody, stained only principal cells but not intercalated cells or other non-CD tubules that are known to express PRR. More direct evidence came from cell-culture experiments showing that exposure of rat IMCD cells to sPRR-His in the nanomolar range induced a remarkable increase in AQP2 expression mimicking the effect of prorenin (44). This result strongly suggests that sPRR has a physiological function.…”

The critical role of the central nervous system (pro)renin receptor in regulating systemic blood pressure

“…Similar effects were also observed in an Ang II-induced rat hypertension model (Wang, et al, 2015). Recently, PRO20 was shown to block prorenin-PRR–induced ENaC (epithelial sodium channel) activation, which is triggered by a reactive oxygen species (ROS) signaling pathway (Lu, et al, 2015). Unique features of PRO20 compared with HRP revealed by our studies include (1) the prominent ability of PRO20 to reduce BP and Ang II formation in hypertensive mice; (2) direct competition of PRO20 with prorenin to prevent binding to the PRR; and (3) the ability of PRO20 to prevent prorenin-induced ERK1/2 phosphorylation in mouse Neuro-2A cells.…”

Unraveling the Physiology of (Pro)Renin Receptor in the Distal Nephron

“…Using this system, we made an initial observation that prorenin treatment in the nanomolar range induced a rapid and transient increase in ENaC-mediated Na + transport (Fig. 2) through Nox4-derived H 2 O 2 29 . Interestingly, renin treatment was largely ineffective.…”

“…In agreement of this observation, multiple studies suggest that prorenin has higher affinity to PRR than renin 30, 31 . The dependence of The Na + stimulatory effect of prorenin on PRR was validated by using a PRR decoy inhibitor PRO20 29 . This effect was independent of canonical RAS since AT1 receptor inhibition with losartan was ineffective (Fig.…”

“…In recent years, the availability of various strains of viable renal PRR knockout (KO) models along with the newly developed PRR decoy inhibitor PRO20 has greatly facilitated the process in unraveling the physiological function of renal PRR. The existing in vivo data suggests that PRO20 acts via inhibition of the RAS during both AngII infusion and deoxycorticosterone acetate (Deoxycorticosterone acetate Deoxycorticosterone acetate DOCA)-salt hypertension 27, 28 although in vitro data shows the RAS-independent effect of this inhibitor on epithelial Na + channel (ENaC) activity 29 . The goal of this review is to highlight recent advances in identifying the roles of PRR in the nephron, particularly in the CD, for regulation of Na + and water balance and blood pressure.…”