Thompson_1991_J.Biol.Chem_266_23856

Reference

Title : The aminosteroid U-73122 inhibits muscarinic receptor sequestration and phosphoinositide hydrolysis in SK-N-SH neuroblastoma cells. A role for Gp in receptor compartmentation - Thompson_1991_J.Biol.Chem_266_23856
Author(s) : Thompson AK , Mostafapour SP , Denlinger LC , Bleasdale JE , Fisher SK
Ref : Journal of Biological Chemistry , 266 :23856 , 1991
Abstract :

The relationship between muscarinic receptor activation of phosphoinositide hydrolysis and the sequestration of cell surface muscarinic receptors has been examined for both intact and digitonin-permeabilized human SK-N-SH neuroblastoma cells. Addition of the aminosteroid 1-[6-[[17 beta-3-methoxyestra-1,3,5(10)-trien-17-yl]amino] hexyl]-1H-pyrrole-2,5-dione (U-73122) to intact cells resulted in the inhibition of oxotremorine-M-stimulated inositol phosphate release and of Ca2+ signaling by greater than 75%. In contrast, when phospholipase C was directly activated by the addition of the calcium ionophore ionomycin, inclusion of U-73122 had little inhibitory effect. Addition of U-73122 to intact cells also inhibited the agonist-induced sequestration of cell surface muscarinic receptors and their subsequent down-regulation with an IC50 value (4.1 microM) similar to that observed for inhibition of inositol phosphate release (3.7 microM). In contrast, when oxotremorine-M-stimulated phosphoinositide hydrolysis was inhibited by depletion of extracellular Ca2+, no reduction in the extent of receptor sequestration was observed. When introduced into digitonin-permeabilized cells, U-73122 more markedly inhibited inositol phosphate release elicited by either oxotremorine-M or guanosine-5'-O-(3-thiotriphosphate) than that induced by added Ca2+. Addition of oxotremorine-M to permeabilized cells resulted in muscarinic receptor sequestration and down-regulation. Both the loss of muscarinic acetylcholine receptors and activation of phosphoinositide hydrolysis in permeabilized cells were inhibited by the inclusion of guanosine-5'-O-(2-thiodiphosphate). The results indicate that the agonist-induced sequestration of muscarinic acetylcholine receptor in SK-N-SH cells requires the involvement of a GTP-binding protein but not the production of phosphoinositide-derived second messenger molecules.

PubMedSearch : Thompson_1991_J.Biol.Chem_266_23856
PubMedID: 1660886

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Citations formats

Thompson AK, Mostafapour SP, Denlinger LC, Bleasdale JE, Fisher SK (1991)
The aminosteroid U-73122 inhibits muscarinic receptor sequestration and phosphoinositide hydrolysis in SK-N-SH neuroblastoma cells. A role for Gp in receptor compartmentation
Journal of Biological Chemistry 266 :23856

Thompson AK, Mostafapour SP, Denlinger LC, Bleasdale JE, Fisher SK (1991)
Journal of Biological Chemistry 266 :23856