Title : Cross talk between m3-muscarinic and beta(2)-adrenergic receptors at the level of receptor phosphorylation and desensitization - Budd_1999_Mol.Pharmacol_56_813 |
Author(s) : Budd DC , Challiss RA , Young KW , Tobin AB |
Ref : Molecular Pharmacology , 56 :813 , 1999 |
Abstract :
In this study we investigated cross talk between m3-muscarinic and beta(2)-adrenergic receptors coexpressed in Chinese hamster ovary (CHO-m3/beta(2)) cells, focusing on two possible mechanisms of regulation. The first mechanism is based on recent in vitro studies demonstrating that G protein-coupled receptor kinase (GRK) activity, the protein kinase responsible for beta(2)-adrenergic receptor homologous phosphorylation and desensitization, may be regulated by calcium/calmodulin and membrane phosphatidylinositol 4, 5-bisphosphate. Stimulation of the phospholipase C signaling pathway via m3-muscarinic receptors in CHO-m3/beta(2) cells increased intracellular free calcium by approximately 10 fold and membrane phosphatidylinositol 4,5-bisphosphate levels decreased by approximately 74%. However, despite these changes the ability of endogenous kinases, possibly the GRKs, to phosphorylate the beta(2)-adrenergic receptor was not altered. The second mechanism investigated involves a direct heterologous phosphorylation of the beta(2)-adrenergic receptor after muscarinic receptor stimulation. Activation of m3-muscarinic receptors did mediate heterologous phosphorylation of beta(2)-adrenergic receptors in a GRK-independent fashion, via protein kinase C. Heterologous beta(2)-adrenergic receptor phosphorylation correlated with receptor desensitization as measured by a loss in guanine-nucleotide sensitive-high affinity agonist binding and reduction in maximal cAMP response. This receptor cross talk may have a profound physiological importance in a wide variety of cell types, for example smooth muscle, where these two receptors are known to be coexpressed. |
PubMedSearch : Budd_1999_Mol.Pharmacol_56_813 |
PubMedID: 10496966 |
Budd DC, Challiss RA, Young KW, Tobin AB (1999)
Cross talk between m3-muscarinic and beta(2)-adrenergic receptors at the level of receptor phosphorylation and desensitization
Molecular Pharmacology
56 :813
Budd DC, Challiss RA, Young KW, Tobin AB (1999)
Molecular Pharmacology
56 :813