Hormone-sensitive cyclic GMP-inhibited cyclic AMP phosphodiesterase in rat adipocytes. Regulation of insulin- and cAMP-dependent activation by phosphorylation.
In 32PO4-labeled adipocytes, isoproterenol (ISO) or physiologically relevant concentrations of insulin rapidly increased phosphorylation of a particulate 135-kDa protein which has been identified as a cGMP-inhibited "low Km" cAMP phosphodiesterase (CGI-PDE) by several criteria, including selective immunoprecipitation with anti-CGI-PDE IgG (Degerman, E., Smith, C.J., Tornqvist, H., Vasta, V., Belfrage, P., and Manganiello, V.C. (1990) Proc. Natl. Acad. Sci. U.S.A. 87, 533-537). The time courses and concentration dependences for phosphorylation of CGI-PDE by ISO and insulin correlated with CGI-PDE activation in the presence of these agents; effects of ISO were somewhat more rapid than those of insulin. Adenosine deaminase, which metabolizes the adenylate cyclase inhibitor adenosine, also rapidly induced phosphorylation and activation of CGI-PDE. Phenylisopropyladenosine (an adenosine deaminase-resistant adenosine analog) prevented or reversed both adenosine deaminase-stimulated phosphorylation and activation of CGI-PDE (IC50 approximately 0.2 nM). Incubation of adipocytes with 0.1 nM insulin in the presence of ISO rapidly produced 30-200% greater activation and phosphorylation of CGI-PDE than the expected added effects of insulin and ISO individually; both effects preceded the insulin-induced decreases in protein kinase A activity and inhibition of lipolysis. These and other results indicate that CGI-PDE can be phosphorylated at distinct sites and activated by cAMP-dependent and insulin-dependent serine kinase(s), that the activation state of CGI-PDE reflects its relative phosphorylation state, and that synergistic phosphorylation/activation of CGI-PDE may be important in the antilipolytic action of insulin.
Smith
C J
CJ
Department of Biochemistry, University of Florence, Italy.
Vasta
V
V
Degerman
E
E
Belfrage
P
P
Manganiello
V C
VC
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D000243:Adenosine Deaminase / Q000494:pharmacology; D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D006152:Cyclic GMP / Q000494:pharmacology*; D004789:Enzyme Activation; D007328:Insulin / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008297:Male; D010660:Phenylisopropyladenosine / Q000494:pharmacology; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains
D007328:Insulin; D010660:Phenylisopropyladenosine; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000243:Adenosine Deaminase; D006152:Cyclic GMP; D007545:Isoproterenol