title: Limited modulation of the mitogen-activated protein kinase pathway by cyclic AMP in rat parotid acinar cells.
abstract: Treatment of rat parotid acinar cells, in vitro, with agents that elevate intracellular cAMP had only limited impact on the ability of EGF to subsequently stimulate MAP-kinase activity or phosphorylation. A time course of cAMP accumulation following in vivo administration of isoproterenol showed the greatest level of cAMP 15 min following the primary injection. Over a 72 hr injection regimen, agonist-stimulated cAMP levels were gradually reduced to control levels while cAMP-dependent protein kinase A (PKA) activity in immunoprecipitates of Raf-1 or MAP-kinase remained elevated. Raf-1 did not undergo phosphorylation following incubation with the catalytic subunit of PKA, suggesting that in normal rat acinar cells proliferation induced by isoproterenol or EGF involves the p21ras-Raf-MAP-kinase signaling cascade despite the presence of cAMP.
authors.affiliation: Department of Oral Biology, University of Florida, Gainesville 32610.
authors.forename: K R
authors.initials: KR
authors.lastname: Purushotham
authors.forename: P L
authors.initials: PL
authors.lastname: Wang
authors.forename: M G
authors.initials: MG
authors.lastname: Humphreys-Beher
mesh_terms: D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000818:Animals; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism / Q000494:pharmacology*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D004676:Myelin Basic Protein / Q000378:metabolism; D010306:Parotid Gland / Q000187:drug effects / Q000201:enzymology*; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D019908:Proto-Oncogene Proteins c-raf; D051381:Rats
chemical_list: D004676:Myelin Basic Protein; D011518:Proto-Oncogene Proteins; D005576:Colforsin; D004815:Epidermal Growth Factor; D000242:Cyclic AMP; D017346:Protein Serine-Threonine Kinases; D019908:Proto-Oncogene Proteins c-raf; D017868:Cyclic AMP-Dependent Protein Kinases; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D007545:Isoproterenol; D015056:1-Methyl-3-isobutylxanthine