title: Dexamethasone effects on beta-adrenergic receptors and adenylate cyclase regulatory proteins Gs and Gi in ROS 17/2.8 cells.
abstract: Treatment of ROS 17/2.8 cells with dexamethasone (dex) increases (-)isoproterenol (ISO)-, PTH-, cholera toxin-, guanine nucleotide-, NaF-, and forskolin-stimulated adenylate cyclase activity. Enhanced hormone stimulation was first apparent 12 h after dex addition. (-)-[3H]Dihydroalprenolol binding, displaceable by ISO, increased up to 2-fold in dex-treated cells. This effect depended on protein synthesis and closely paralleled the extent and time course of the increase in adenylate cyclase stimulation. In dex-treated cells there was also an increase in the maximum velocity of guanyl-5'-yl imidodiphosphate-stimulated adenylate cyclase, a decrease in the lag time for guanyl-5'-yl imidodiphosphate enzyme activation in the presence of ISO from 3 to 1 min, increased stimulation of adenylate cyclase by cholera toxin, and increased labeling of 47,000 and 42,000 mol wt proteins by [32P]NAD in the presence of cholera toxin. [32P]NAD ribosylation in the presence of pertussis toxin resulted in the labeling of 40,000 mol wt protein, which was also increased by 20-50% in dex-treated cells. However, pertussis toxin treatment did not augment or reduce the effect on hormone stimulation, although it increased the cAMP response to PTH and (-)ISO. These findings suggest that dex increases (-)ISO stimulation of adenylate cyclase in ROS 17/2.8 cells by jointly increasing the number of hormone receptors and the abundance of Gs, the guanine nucleotide binding regulatory protein.
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002460:Cell Line; D002772:Cholera Toxin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D003907:Dexamethasone / Q000494:pharmacology*; D004082:Dihydroalprenolol / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000378:metabolism*; D006165:Guanylyl Imidodiphosphate / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008970:Molecular Weight; D009243:NAD / Q000378:metabolism; D012516:Osteosarcoma / Q000378:metabolism*; D051381:Rats; D011943:Receptors, Adrenergic, beta / Q000187:drug effects / Q000378:metabolism*
chemical_list: D011943:Receptors, Adrenergic, beta; D009243:NAD; D000246:Adenosine Diphosphate Ribose; D006165:Guanylyl Imidodiphosphate; D004082:Dihydroalprenolol; D003907:Dexamethasone; D002772:Cholera Toxin; D003513:Cycloheximide; D000242:Cyclic AMP; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D007545:Isoproterenol