All aspects of cardiovascular function are regulated by receptors of the seven transmembrane receptor (7TMR) family. The largest of all the receptor families, it includes receptors for catecholamines, acetylcholine, angiotensin, adenosine and endothelins. A universal mechanism regulating these receptors is desensitization of heterotrimeric G-protein signaling. Classically, this is mediated by a two-step process in which activated receptors are phosphorylated by G-protein-coupled receptor kinases (GRKs) leading to the binding of a ?- arrestin (? arr) molecule, which sterically interdicts further activation of the G-protein. More recently it has become clear that ? arrs can also serve as multifunctional endocytic and signaling adaptors, which can also activate additional pathways involved in such physiological outcomes as chemotaxis and anti-apoptosis, thus regulating cardiovascular function in atherosclerosis, restenosis, and cardiac hypertrophy. Moreover, for several receptors, including the ?1 and ?2-adrenergic receptors (ARs) and angiotensin 1A receptor (AT1AR), amongst others, ligands can be found which disproportionately activate either G-protein or ? arr mediated signaling - i.e. "biased ligands". Such compounds have potentially unique therapeutic properties. Accordingly, this proposal has three closely linked aims, which involve a focus on elucidating the molecular mechanisms by which 2arrs mediate signaling by 7TMRs. Our goals are: 1) to elucidate the full extent of ? arr mediated signaling networks downstream of cardiovascular 7TMRs such as the AT1AR and ? 2-AR using the approaches of global cellular phosphoproteomics and systems biology;2) to develop ? arr-biased ligands for the ? 2-AR via high throughput and targeted screening;and 3)to elucidate the molecular and biophysical basis of such signaling in terms of ligand specific conformational alterations in ? arrs via analysis of receptor phosphorylation sites, development of conformationally specific antigen binding fragments of antibodies (Fabs) and crystallographic techniques. Our hypothesis is that the phosphorylation of distinct sites on receptors by different GRKs leads to structurally and functionally distinct activated conformations of the receptors and ? arrs which mediate distinct signaling outcomes. By understanding the functional signaling consequences and structural basis of ? arr-biased agonism we will lay the basis for the development of a novel class of therapeutic agents.
Relevance Some of the most important drugs used to treat cardiovascular disease such as " ? blockers" (? -adrenergic receptor antagonists) or "ARBs" (angiotensin receptor blockers) work through specific receptors on the outside of cells. Here we seek to understand, at a molecular level, a newly discovered mechanism by which these receptors signal to the inside of the cell, in order to lay the basis for an entirely novel class of therapeutic agents for the treatment of cardiovascular and other diseases.
|Kahsai, Alem W; Wisler, James W; Lee, Jungmin et al. (2016) Conformationally selective RNA aptamers allosterically modulate the Î²2-adrenoceptor. Nat Chem Biol 12:709-16|
|Thomsen, Alex R B; Plouffe, Bianca; Cahill 3rd, Thomas J et al. (2016) GPCR-G Protein-Î²-Arrestin Super-Complex Mediates Sustained G Protein Signaling. Cell 166:907-19|
|Staus, Dean P; Strachan, Ryan T; Manglik, Aashish et al. (2016) Allosteric nanobodies reveal the dynamic range and diverse mechanisms of G-protein-coupled receptor activation. Nature 535:448-52|
|Wisler, James W; Harris, Emily M; Raisch, Michael et al. (2015) The role of Î²-arrestin2-dependent signaling in thoracic aortic aneurysm formation in a murine model of Marfan syndrome. Am J Physiol Heart Circ Physiol 309:H1516-27|
|Lefkowitz, Robert J (2015) Inspiring the next generation of physician-scientists. J Clin Invest 125:2905-7|
|Kotula, Jonathan W; Sun, Jinpeng; Li, Margie et al. (2014) Targeted disruption of Î²-arrestin 2-mediated signaling pathways by aptamer chimeras leads to inhibition of leukemic cell growth. PLoS One 9:e93441|
|Strachan, Ryan T; Sun, Jin-peng; Rominger, David H et al. (2014) Divergent transducer-specific molecular efficacies generate biased agonism at a G protein-coupled receptor (GPCR). J Biol Chem 289:14211-24|
|Tang, Wei; Strachan, Ryan T; Lefkowitz, Robert J et al. (2014) Allosteric modulation of Î²-arrestin-biased angiotensin II type 1 receptor signaling by membrane stretch. J Biol Chem 289:28271-83|
|Staus, Dean P; Wingler, Laura M; Strachan, Ryan T et al. (2014) Regulation of Î²2-adrenergic receptor function by conformationally selective single-domain intrabodies. Mol Pharmacol 85:472-81|
|Wisler, James W; Xiao, Kunhong; Thomsen, Alex R B et al. (2014) Recent developments in biased agonism. Curr Opin Cell Biol 27:18-24|
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