Protein kinase C and a viral K-RAS protein cooperatively enhance the response of adenylate cyclase to stimulators.
The protein kinase C stimulator TPA (12-O-tetradecanoyl phorbol-13-acetate) enhanced the responsiveness of adenylate cyclase to IPR (isoproterenol) and PGE1 (prostaglandin E1) in quiescent tsKSV-NRK cells at the nonpermissive 41 degrees C. Reactivating the thermolabile mitogenic/oncogenic K-ras protein in tsKSV-NRK cells by dropping the temperature to 36 degrees C also enhanced the responsiveness of adenylate cyclase to IPR and PGE1. The enhancement was transient and peaked at 6 hours after the temperature shift. This enhanced responsiveness was specifically due to the reactivated viral K-ras protein rather than the temperature shift because the same temperature shift did not affect adenylate cyclase responsiveness in uninfected NRK cells, nor was it a result of the mitogenic stimulus since reacting the mitogenic pp60v-src protein in tsASV-NRK cells did not affect adenylate cyclase responsiveness. The increased responsiveness of adenylate cyclase at 6 hours after the temperature shift was not a result of elevated membrane-associated PKC activity. However, the reactivated viral K-ras protein strongly increased the stimulability of membrane-associated PKC by TPA and it further increased TPA's ability to enhance the responsiveness of adenylate cyclase to IPR and PGE1. Thus, a viral K-ras protein and membrane-associated protein kinase C can cooperate to increase the responsiveness of adenylate cyclase to agonists.
Franks
D J
DJ
Department of Pathology, Faculty of Health Sciences, University of Ottawa, Ontario, Canada.
Durkin
J P
JP
Whitfield
J F
JF
D000262:Adenylyl Cyclases / Q000378:metabolism*; D000527:Alprostadil / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D000242:Cyclic AMP / Q000096:biosynthesis; D004789:Enzyme Activation / Q000187:drug effects; D011905:Genes, ras; D066298:In Vitro Techniques; D007545:Isoproterenol / Q000494:pharmacology*; D009856:Oncogene Proteins, Viral / Q000502:physiology*; D011493:Protein Kinase C / Q000502:physiology*; D051381:Rats; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors
D009856:Oncogene Proteins, Viral; D000242:Cyclic AMP; D011493:Protein Kinase C; D000262:Adenylyl Cyclases; D000527:Alprostadil; D007545:Isoproterenol; D013755:Tetradecanoylphorbol Acetate