Alpha/1-Adrenergic receptors (alpha/1-AR) mediate important effects f the sympathetic nervous system, such as arteriolar constriction. Three alpha/1-ARs have been cloned. However, the physiological significance of this subtype diversity remains unclear, since they are functionally similar in their ligand recognition and signaling properties, and are often coexpressed. The goal of this proposal is to more clearly define their physiological function and investigate possible differences between these subtypes. In our efforts to understand signal transduction by alpha/1-ARs, we intend to focus on a number of mutants that can clarify which residues are involved in subtype selectivity, and if a particular residue(s) is involved in transducing a signal to the G-protein. Secondly, studies will be performed by developing a model system to study alpha/1-AR subtype inactivation by gene targeting. The FRTL-5 cell line is an ideal model system since its alpha/1-AR signaling characteristics and receptor-mediation of thyroid metabolism have been well characterized. In this cell line only a single alpha/1-AR (alpha/1B) appears to be expressed that can couple to its effector pathways via two distinct G- proteins. However, expression of another subtype(s), at low level, cannot be excluded. To test this hypothesis, I propose to inactivate the alpha/1B-AR and then assess its role in thyroid regulation. The generation of an alpha/1B-AR deficient cell line will also be advantageous in the analysis of the alpha/1B-AR mutants generated in Specific Aim 1. Specifically, our aims are the following: i) To undertake structure-function studies using site-directed mutagenesis in determining which residues are involved in subtype selectivity. ii) To fully characterize and understand the properties of a constitutively activated alpha/1B-AR that has been mutated in the third transmembrane domain. iii) To achieve a double allele disruption of the alpha/1B-AR gene by homologous recombination in somatic FRTL-5 cells and generate an alpha/1B- AR deficient cell line for mutational studies.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
1R01HL052544-01A1
Application #
2229971
Study Section
Pharmacology A Study Section (PHRA)
Project Start
1995-07-01
Project End
1999-06-30
Budget Start
1995-07-01
Budget End
1996-06-30
Support Year
1
Fiscal Year
1995
Total Cost
Indirect Cost
Name
Cleveland Clinic Lerner
Department
Type
DUNS #
017730458
City
Cleveland
State
OH
Country
United States
Zip Code
44195
Porter, J E; Perez, D M (2000) Influence of a lysine 331 counterion on the pK(a) of aspartic acid 125: evidence for a salt-bridge interaction and role in alpha(1b)-adrenergic receptor activation. J Pharmacol Exp Ther 292:440-8
Porter, J E; Perez, D M (1999) Characteristics for a salt-bridge switch mutation of the alpha(1b) adrenergic receptor. Altered pharmacology and rescue of constitutive activity. J Biol Chem 274:34535-8
Waugh, D J; Gaivin, R J; Damron, D S et al. (1999) Binding, partial agonism, and potentiation of alpha(1)-adrenergic receptor function by benzodiazepines: A potential site of allosteric modulation. J Pharmacol Exp Ther 291:1164-71
Zuscik, M J; Piascik, M T; Perez, D M (1999) Cloning, cell-type specificity, and regulatory function of the mouse alpha(1B)-adrenergic receptor promoter. Mol Pharmacol 56:1288-97
Perez, D M; Hwa, J; Zhao, M M et al. (1998) Molecular mechanisms of ligand binding and activation in alpha 1-adrenergic receptors. Adv Pharmacol 42:398-403
Porter, J E; Edelmann, S E; Waugh, D J et al. (1998) The agonism and synergistic potentiation of weak partial agonists by triethylamine in alpha 1-adrenergic receptor activation: evidence for a salt bridge as the initiating process. Mol Pharmacol 53:766-71
Zhao, M M; Gaivin, R J; Perez, D M (1998) The third extracellular loop of the beta2-adrenergic receptor can modulate receptor/G protein affinity. Mol Pharmacol 53:524-9
Hwa, J; Gaivin, R; Porter, J E et al. (1997) Synergism of constitutive activity in alpha 1-adrenergic receptor activation. Biochemistry 36:633-9
Zhao, M M; Hwa, J; Perez, D M (1996) Identification of critical extracellular loop residues involved in alpha 1-adrenergic receptor subtype-selective antagonist binding. Mol Pharmacol 50:1118-26
Hwa, J; Perez, D M (1996) The unique nature of the serine interactions for alpha 1-adrenergic receptor agonist binding and activation. J Biol Chem 271:6322-7

Showing the most recent 10 out of 12 publications