The (pro)renin receptor ((P)RR) and soluble (pro)renin receptor (s(P)RR) in pregnancy

The (pro)renin receptor ((P)RR) is a multi-functional protein that can be proteolytically cleaved and released in a soluble form (s(P)RR). Recently, the (P)RR and s(P)RR have become of interest in pregnancy and its associated pathologies. This is because the (P)RR not only activates tissue renin angiotensin systems, but it is also an integral component of vacuolar-ATPase, activates the wingless/integrated (Wnt)/β-catenin and extracellular signal regulated kinases 1 and 2/mitogen-activated protein kinase signalling pathways, and stabilises the β subunit of pyruvate dehydrogenase. Additionally, s(P)RR is detected in plasma and urine, and maternal plasma levels are elevated in pregnancy complications including fetal growth restriction, preeclampsia and gestational diabetes mellitus. Therefore, s(P)RR has potential as a biomarker for these pregnancy pathologies. Preliminary functional findings suggest that s(P)RR may be important for regulating fluid balance, inflammation and blood pressure, all of which contribute to a successful pregnancy. The (P)RR and s(P)RR regulate pathways that are known to be important in maintaining pregnancy, however their role in the physiological context of pregnancy is poorly characterised. This review summarises the known and potential functions of the (P)RR and s(P)RR in pregnancy, and how their dysregulation may contribute to pregnancy complications. It also highlights the need for further research into the source and function of s(P)RR in pregnancy. Soluble (P)RR levels could be indicative of placental, kidney or liver dysfunction and therefore be a novel clinical biomarker, or therapeutic target, to improve the detection and treatment of pregnancy pathologies.