PS-B12-11: FUNCTIONAL VERSATILITY OF (PRO) RENIN RECEPTOR CLARIFIED BY STRUCTURAL AND EVOLUTIONARY ANALYSES

Abstract

Objective: (Pro)renin receptor [(P)RR] is a single-span membrane protein originally identified as a regulator of the renin-angiotensin-aldosterone system. (P)RR reportedly exerts various functions, including an accessory protein of vacuolar ATPase complex and a component of Wnt receptor complex. The soluble form of (P)RR [s(P)RR] which comprises of most of extracellular domain (ECD) exerts an antidiuretic action. although the versatile functions should be mediated through the interactions between (p)rr ecd and its respective binding partners, the one-to-many bindings has not been fully explained. Here we investigated the binding mode of this receptor by structural and evolutionary analyses using three-dimensional structural models of (P)RR, which were predicted by the AlphaFold2 (AF2) program, a machine learning-based algorithm capable of predicting protein structure to near experimental accuracy. Design and method: Monoclonal antibodies against (P)RR reduce the Wnt/beta-catenin-dependent development of pancreatic ductal adenocarcinoma (PDAC), the most common pancreatic cancer. Antibodies against two (P)RR regions (residues 47–60 and 200–213) located in ECD reduce the proliferation of human PDAC cells in vitro. The spatial distribution of the two regions was examined using human (P)RR AF2 structural models (monomer and dimer). The evolutionary conservation profile and hydrophobicity were mapped on the models. Results: The dimer structure predicted by AF2 shows that (P)RR homodimerizes via ECD, which explains the experimentally proven dimer formation. The 47–60 and 200–213 regions of (P)RR formed a continuous surface patch on the structural model, which comprised evolutionarily conserved hydrophobic residues. The dimer model revealed the presence of two hand-like grooves, with 47–60 and 200–213 regions as its palm and 270–296 region (intrinsically disordered region, IDR) as its fingers. Conclusions: Considering conformational flexibility of IDR allowing for multiple protein interactions, we propose that the grooves may act as a binding interface with Wnt signaling molecules and antibodies against the grooves probably interfere with the formation of Wnt receptor complex due to steric hindrance and direct competition with the binding interface residues. The hydrophobic nature of the grooves may explain why (P)RR shows one-to-many bindings underpinning its functional versatility. This study provides new insights into the binding mode of (P)RR for the first time. s(P)RR is considered a useful biomarker for diseases, including essential hypertension and cancer. Our findings may help explore a new treatment and biomarker testing of human diseases, and contribute to quality of life in a longevity society.