Structural insights into angiotensin receptor signaling modulation by balanced and biased agonists

Abstract

AbstractThe peptide hormone angiotensin II regulates blood pressure mainly through the type 1 angiotensin II receptor AT1R and its downstream signaling proteins Gq and β‐arrestin. AT1R blockers, clinically used as antihypertensive drugs, inhibit both signaling pathways, whereas AT1R β‐arrestin‐biased agonists have shown great potential for the treatment of acute heart failure. Here, we present a cryo‐electron microscopy (cryo‐EM) structure of the human AT1R in complex with a balanced agonist, Sar1‐AngII, and Gq protein at 2.9 Å resolution. This structure, together with extensive functional assays and computational modeling, reveals the molecular mechanisms for AT1R signaling modulation and suggests that a major hydrogen bond network (MHN) inside the receptor serves as a key regulator of AT1R signal transduction from the ligand‐binding pocket to both Gq and β‐arrestin pathways. Specifically, we found that the MHN mutations N1113.35A and N2947.45A induce biased signaling to Gq and β‐arrestin, respectively. These insights should facilitate AT1R structure‐based drug discovery for the treatment of cardiovascular diseases.