This FIRCA application represents a new direction of the Parent Grant which is entitled """"""""Modulation of Muscarinic Responses by Inositol Lipids"""""""". The focus of the proposed project is to test the hypotheses that: (a) pharmacological agents which modulate the conformation of muscarinic receptors in a positive allosteric manner are able to discriminate in their binding to various subtypes of these receptors; (b) such selectivity in binding is reflected in a preferential potentiation of the second messenger signals coupled to certain muscarinic receptor subtypes more than others. This pharmacological profile should result in fine-tuning of signal transduction mechanisms coupled to activation of muscarinic receptors in tissues endowed with the presence of multiple receptor subtypes. Alcuronium, which is a representative of this class of drugs, has been discovered in the laboratory of Dr. Tucek to increase the binding of certain ligands to muscarinic receptors in a manner which suggests that it interacts with the receptor at a distinct domain in relation to the binding site of conventional competitive muscarinic antagonists. This interaction results in a unique enhancement of the affinity of the latter class of ligands. Most other muscarinic allosteric modulators regulate the receptor conformation in a negative fashion. Alcuronium will be used in the proposed studies as a prototype compound. This project complements the long-standing interest of the P.I. in the mechanisms of allosteric regulation of muscarinic receptors. It also focuses on research questions which are closely related to the specific aims of the Parent Grant in terms of modulation of receptor function at the level of agonist-receptor interaction. The parallel goal of the Parent Grant is to explore the cross-talk between intracellular second messenger mechanisms which controls the responsiveness of muscarinic receptors.

Agency
National Institute of Health (NIH)
Institute
Fogarty International Center (FIC)
Type
Small Research Grants (R03)
Project #
5R03TW000171-02
Application #
2291647
Study Section
Special Emphasis Panel (SRC (01))
Project Start
1993-04-01
Project End
1996-03-31
Budget Start
1994-04-01
Budget End
1995-03-31
Support Year
2
Fiscal Year
1994
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Psychiatry
Type
Schools of Medicine
DUNS #
168559177
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Jakubik, J; El-Fakahany, E E; Tucek, S (2000) Evidence for a tandem two-site model of ligand binding to muscarinic acetylcholine receptors. J Biol Chem 275:18836-44
Dolezal, V; Tucek, S (1999) Calcium channels involved in the inhibition of acetylcholine release by presynaptic muscarinic receptors in rat striatum. Br J Pharmacol 127:1627-32
Lysikova, M; Fuksova, K; Elbert, T et al. (1999) Subtype-selective inhibition of [methyl-3H]-N-methylscopolamine binding to muscarinic receptors by alpha-truxillic acid esters. Br J Pharmacol 127:1240-6
Dolezal, V; Tucek, S (1998) The effects of brucine and alcuronium on the inhibition of [3H]acetylcholine release from rat striatum by muscarinic receptor agonists. Br J Pharmacol 124:1213-8
Jakubik, J; Haga, T; Tucek, S (1998) Effects of an agonist, allosteric modulator, and antagonist on guanosine-gamma-[35S]thiotriphosphate binding to liposomes with varying muscarinic receptor/Go protein stoichiometry. Mol Pharmacol 54:899-906
Jakubik, J; Bacakova, L; El-Fakahany, E E et al. (1997) Positive cooperativity of acetylcholine and other agonists with allosteric ligands on muscarinic acetylcholine receptors. Mol Pharmacol 52:172-9
Jakubik, J; Tucek, S (1995) Positive allosteric interactions on cardiac muscarinic receptors: effects of chemical modifications of disulphide and carboxyl groups. Eur J Pharmacol 289:311-9
Jakubik, J; Bacakova, L; el-Fakahany, E E et al. (1995) Constitutive activity of the M1-M4 subtypes of muscarinic receptors in transfected CHO cells and of muscarinic receptors in the heart cells revealed by negative antagonists. FEBS Lett 377:275-9
Jakubik, J; Bacakova, L; el-Fakahany, E E et al. (1995) Subtype selectivity of the positive allosteric action of alcuronium at cloned M1-M5 muscarinic acetylcholine receptors. J Pharmacol Exp Ther 274:1077-83
Proska, J; Tucek, S (1995) Competition between positive and negative allosteric effectors on muscarinic receptors. Mol Pharmacol 48:696-702

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