The objective of the proposed research is to elucidate the molecular mechanisms involved in desensitization of adrenergic receptors by catecholamines and other agonists. Previous studies in isolated cells in culture have documented several distinct steps involved in the overall process of desensitization; however, the molecular nature of the changes involved remains unknown. Recent studies indicate the widespread occurrence and clinical significance of desensitization of adrenergic receptors in various human tissues, in particular heart, lung, leukocytes, and lymphocytes. Furthermore, preliminary studies suggest that the cellular mechanisms involved in desensitization in these tissues in intact animals are probably similar to those demonstrated in cultured cells. Thus, further studies of the molecular mechanisms involved in desensitization in cultured cell lines, which are more amenable to study, will likely lead to information that will be of relevance to understanding desensitization in various tissues in man. The proposed studies will use recently developed techniques involving short-time assays with intact cells to study the molecular events involved in desensitization of beta-adrenergic receptors (BAR). These assays will further investigate the involvement of internalization of BAR in desensitization of cultured human astrocytoma cells (1321N1) and will be used to identify inhibitors of the various biochemical reactions involved in desensitization. The possible involvement of the cytoskeletal system, cyclic-AMP-independent phosphorylation, transmethylation reactions, and various ions and ion gradients in desensitization will be investigated. Other studies will attempt to develop broken cell systems in which biochemical studies of receptor modification can be carried out. Finally, the intact cell binding techniques developed for study of BAR will also be applied to a study of the likely involvement of similar changes in alpha-1-adrenergic receptors on intact cells in culture.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Modified Research Career Development Award (K04)
Project #
5K04HL001593-02
Application #
3073897
Study Section
Pharmacology A Study Section (PHRA)
Project Start
1985-09-01
Project End
1990-08-31
Budget Start
1986-09-01
Budget End
1987-08-31
Support Year
2
Fiscal Year
1986
Total Cost
Indirect Cost
Name
University of Missouri-Columbia
Department
Type
Schools of Medicine
DUNS #
112205955
City
Columbia
State
MO
Country
United States
Zip Code
65211
Zhu, S J; Toews, M L (1994) Intact cell binding properties of cells expressing altered beta-adrenergic receptors. Mol Pharmacol 45:255-61
Toews, M L; Arneson-Rotert, L J; Liewer, S A (1993) Bicarbonate induces sensitization of cyclic AMP accumulation by intact 1321N1 human astrocytoma cells. J Pharmacol Exp Ther 264:1211-7
Nogami, M; Romberger, D J; Rennard, S I et al. (1993) Agonist-induced desensitization of beta-adrenoceptors of bovine bronchial epithelial cells. Clin Sci (Lond) 85:651-7
Zhu, S J; Toews, M L (1993) Effects of antimycin A on the binding properties of beta and alpha-1 adrenergic receptors measured on intact cells. J Pharmacol Exp Ther 267:123-7
Toews, M L; Hoffman, J M; Liewer, S A et al. (1992) Serum-induced sensitization of cyclic AMP accumulation in C62B rat glioma cells. J Pharmacol Exp Ther 262:471-8
Johnson, R A; Arneson-Rotert, L J; Hoffman, J M et al. (1991) Serum-induced sensitization of cyclic AMP accumulation in 1321N1 human astrocytoma cells. Mol Pharmacol 39:399-406
Cowlen, M S; Barnes, M R; Toews, M L (1990) Regulation of histamine H1 receptor-mediated phosphoinositide hydrolysis by histamine and phorbol esters in DDT1 MF-2 cells. Eur J Pharmacol 188:105-12
Johnson, R A; Toews, M L (1990) Protein kinase C activators sensitize cyclic AMP accumulation by intact 1321N1 human astrocytoma cells. Mol Pharmacol 37:296-303
Hoover, R K; Toews, M L (1990) Activation of protein kinase C inhibits internalization and downregulation of muscarinic receptors in 1321N1 human astrocytoma cells. J Pharmacol Exp Ther 253:185-91
Hoover, R K; Toews, M L (1989) Evidence for an agonist-induced, ATP-dependent change in muscarinic receptors of intact 1321N1 cells. J Pharmacol Exp Ther 251:63-70

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