Author : Yubo Cao
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (129 download)
Book Synopsis Understanding the Molecular Determinants for Functional Selectivity of the Angiotensin II Type 1 Receptor by : Yubo Cao
Download or read book Understanding the Molecular Determinants for Functional Selectivity of the Angiotensin II Type 1 Receptor written by Yubo Cao and published by . This book was released on 2021 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "Hypertension and its associated cardiovascular risks can be attributed to angiotensin II (AngII), which regulates blood volume and vascular resistance through the AngII type 1 receptor (AT1R). As a G protein-coupled receptor (GPCR), the AT1R signals by coupling to G proteins (G[alpha]q/11, G[alpha]12/13, G[alpha]i1/2/3) and [beta]-arrestins ([beta]-arr1 and 2, which act both as endocytic and signaling adaptors) to mediate its physiological effects. While most drugs that target the AT1R act by blocking the activation of the receptor and thereby attenuating all of its downstream signaling pathways indiscriminately, studies have highlighted that certain AT1R-mediated pathways may promote beneficial cardio-protective effects. Thus, recent efforts have been focused on developing ligands that stabilize unique conformations in the AT1R that promote selective signaling pathway and downstream effector activation - a phenomenon known as biased signaling or functional selectivity. However, development of such efficacious biased ligands have been met with major hurdles, as although it is proposed that AngII binding induces a conformational change in the AT1R that favors its coupling to G proteins and [beta]-arrs, the molecular determinants for activating specific signaling pathways remain unknown. Moreover, the involvement of each signaling pathway towards specific cellular outcomes is unresolved.In the first half of my thesis, I begin by describing the technical application of our enhanced bystander BRET biosensors to monitor [beta]-arr-mediated internalization and trafficking for different classes of GPCRs, published as a book chapter. These techniques, along with conformational fluorescein arsenical hairpin (FlAsH)-BRET sensors and high-resolution fluorescence microscopy, were used extensively in my second publication investigating the [beta]-arr-mediated trafficking and signaling of three naturally occurring AT1R variants: A163T, T282M, and C289W. We found that some variants, most notably T282M, imposed distinct conformations in [beta]-arrestin and decreased the avidity of the receptor for [beta]-arr and residency with [beta]-arr in endosomes. Ultimately, T282M decreased [beta]-arr-dependent ERK1/2 activation, increased the rate of receptor recycling to the PM, and impaired AngII-mediated proliferation, highlighting the importance of [beta]-arrestin-mediated MAPK activation and endosomal receptor-[beta]-arrestin complex stabilization in the mitogenic response of AT1R.The latter half of my thesis focuses on pinpointing the amino acid residues in the AT1R involved in engaging specific signaling pathways to identify the molecular determinants of the AT1R governing its functional selectivity. In my third manuscript (currently under review), using molecular dynamics simulations, dynamic allostery analysis, and functional BRET assays, we identified a network of residues involved in allosteric communication from the AngII binding site to the putative Gq coupling sites and another network to the [beta]-arrestin2 coupling sites. Finally in my fourth manuscript (currently in preparation), I've also conducted an alanine scan of the 359 amino acids in the AT1R to systematically characterize the Gq and [beta]-arrestin activation profile of these mutants. I identified novel orthosteric AngII binding sites and key residues in AT1R that elicit unique signal transduction behaviors, and by stratifying the different mutants according to their signaling profiles, establish networks of residues that are critical for distinct signaling pathways. Altogether, the findings in my thesis will help to understand the molecular mechanism for activating distinct AT1R signaling pathways and provide new insights towards the development of efficacious biased ligands and better-targeted therapeutics against the AT1R"--
