Angiotensin receptor blockers (ARB) used in the treatment of hypertension, heart-failure and other cardiovascular disease conditions prevents activation and signal transduction by the angiotensin type 1 receptor (AT1) for angiotensin II (Ang II). Binding of Ang II to the AT1 receptor activates signal-transduction that leads to mobilization of intracellular calcium, activation of protein kinases, and activation of gene transcription. Yet the molecular mechanism of modulation of these processes by Ang II or ARBs via binding to the AT1 receptor is not clear. Our long-term goal is to understand how the Ang ll-bound AT1 receptor activates the multiple signal transduction process and how ARBs affect this process. Towards this goal, we have developed Ang II- analogs and receptor mutants that activate the ERK-signaling in absence of the G-protein activation. The current proposal will address two issues: (1) how are the AT1-selective ligands guided to the binding pocket in the receptor? and (2) what are the in vivo consequences of the differences between the G-protein mediated and the G-protein independent AT1 receptor signaling? We will determine whether the extracellular loops (ECL) directly participate in the ligand receptor interaction and the activation/inhibition of the AT1 receptor. We anticipate that ECL-2 interacts with the TM domain in an inactive state (R) of the receptor as well as with the Ang II in the activated state (Specific Aim 1). We have discovered that the AT1 receptor engages the beta-arrestin and its fragments in the Ang II activated cells which are absent under other conditions. We will test the hypothesis that site-specific beta-arrestin proteolysis is a novel signaling mode with functional consequences. We will determine the site of beta-arrestin cleavage and its functional consequences in Ang II activated cells (Specific Aim 2). G-protein-dependent AT1 receptor signaling differs from G-protein- independent signaling due to the fact that it causes nuclear translocation of ERK. We will determine the role of Ang ll/AT1 receptor-induced nuclear translocation of ERK 1/2 in activation of gene expression (Specific Aim 3). These studies are essential for a better understanding of the mechanism of Ang II/AT1 receptor action and the development of improved remedies targeting the AT1 receptor. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL057470-09
Application #
7102892
Study Section
Hypertension and Microcirculation Study Section (HM)
Program Officer
Lin, Michael
Project Start
1997-08-20
Project End
2010-06-30
Budget Start
2006-07-01
Budget End
2007-06-30
Support Year
9
Fiscal Year
2006
Total Cost
$347,625
Indirect Cost
Name
Cleveland Clinic Lerner
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
135781701
City
Cleveland
State
OH
Country
United States
Zip Code
44195
Takezako, Takanobu; Unal, Hamiyet; Karnik, Sadashiva S et al. (2018) The non-biphenyl-tetrazole angiotensin AT1 receptor antagonist eprosartan is a unique and robust inverse agonist of the active state of the AT1 receptor. Br J Pharmacol 175:2454-2469
Singh, Khuraijam Dhanachandra; Karnik, Sadashiva S (2016) Angiotensin Receptors: Structure, Function, Signaling and Clinical Applications. J Cell Signal 1:
Tirupula, Kalyan C; Zhang, Dongmei; Osbourne, Appledene et al. (2015) MAS C-Terminal Tail Interacting Proteins Identified by Mass Spectrometry- Based Proteomic Approach. PLoS One 10:e0140872
Tirupula, Kalyan C; Ithychanda, Sujay S; Mohan, Maradumane L et al. (2015) G protein-coupled receptors directly bind filamin A with high affinity and promote filamin phosphorylation. Biochemistry 54:6673-83
Ithychanda, Sujay Subbayya; Fang, Xianyang; Mohan, Maradumane L et al. (2015) A mechanism of global shape-dependent recognition and phosphorylation of filamin by protein kinase A. J Biol Chem 290:8527-38
Zhang, Haitao; Unal, Hamiyet; Gati, Cornelius et al. (2015) Structure of the Angiotensin receptor revealed by serial femtosecond crystallography. Cell 161:833-44
Zhang, Haitao; Unal, Hamiyet; Desnoyer, Russell et al. (2015) Structural Basis for Ligand Recognition and Functional Selectivity at Angiotensin Receptor. J Biol Chem 290:29127-39
Takezako, Takanobu; Unal, Hamiyet; Karnik, Sadashiva S et al. (2015) Structure-Function Basis of Attenuated Inverse Agonism of Angiotensin II Type 1 Receptor Blockers for Active-State Angiotensin II Type 1 Receptor. Mol Pharmacol 88:488-501
Karnik, Sadashiva S; Unal, Hamiyet; Kemp, Jacqueline R et al. (2015) International Union of Basic and Clinical Pharmacology. XCIX. Angiotensin Receptors: Interpreters of Pathophysiological Angiotensinergic Stimuli [corrected]. Pharmacol Rev 67:754-819
Kemp, Jacqueline R; Unal, Hamiyet; Desnoyer, Russell et al. (2014) Angiotensin II-regulated microRNA 483-3p directly targets multiple components of the renin-angiotensin system. J Mol Cell Cardiol 75:25-39

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