title: cAMP inhibits the insulin-stimulated mitogen-activated protein kinase pathway in rat hepatoma H4EII cells.
abstract: Effects of cAMP on insulin-stimulated mitogen-activated protein (MAP) kinase pathway were examined using rat hepatoma H4EII cells. MAP kinase was rapidly activated and reached a peak 3 min after the stimulation by insulin. Forskolin (1 microM) and 8(4-chlorophenylthio)cAMP (8-CPT-cAMP) (0.1 mM) inhibited the insulin-stimulated MAP kinase activity. Pretreatment of the cells with H-8 (50 microM), a cAMP-dependent protein kinase inhibitor, enhanced the insulin-stimulated MAP kinase activity and partially restored the inhibitory effect of cAMP. Furthermore, insulin-induced phosphorylation of MAP kinase was inhibited by 8-CPT-cAMP, and the inhibition was restored by H-8. 8-CPT-cAMP did not inhibit the autophosphorylation of insulin receptor. These data indicate that elevation of intracellular cAMP blocks the insulin-stimulated MAP kinase pathway downstream of insulin receptor.
authors.affiliation: Department of Biochemistry, Yamaguchi University School of Medicine, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Nagasaka
authors.forename: K
authors.initials: K
authors.lastname: Kaku
authors.forename: K
authors.initials: K
authors.lastname: Nakamura
authors.forename: T
authors.initials: T
authors.lastname: Kaneko
mesh_terms: D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D005994:Glycerophosphates / Q000494:pharmacology; D007328:Insulin / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology; D008114:Liver Neoplasms, Experimental / Q000201:enzymology*; D008345:Manganese / Q000494:pharmacology; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology; D051381:Rats; D011972:Receptor, Insulin / Q000378:metabolism; D012969:Sodium Fluoride / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology; D014407:Tumor Cells, Cultured
chemical_list: D005994:Glycerophosphates; D007328:Insulin; D007546:Isoquinolines; D010879:Piperazines; D013873:Thionucleotides; D005576:Colforsin; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D008345:Manganese; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; C053177:N-(2-(methylamino)ethyl)-5-isoquinolinesulfonamide; D012969:Sodium Fluoride; D000242:Cyclic AMP; D011972:Receptor, Insulin; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D002118:Calcium; C031463:beta-glycerophosphoric acid