Mechanisms of cAMP-mediated gene induction: examination of renal epithelial cell mutants affected in the catalytic subunit of the cAMP-dependent protein kinase.
The precise mechanistic role of the cAMP-dependent protein kinase (cAMP-PK) in cAMP-mediated gene induction remains unclear. Renal epithelial cell mutants were compared to the LLC-PK1 parental cell line for induction of the cAMP-responsive urokinase-type plasminogen activator (uPA) gene, as quantitated by the technique of mRNA solution hybridization. The FIB4 and FIB6 mutants, which possess less than 10% parental cAMP-PK catalytic (C) subunit activity, showed markedly diminished uPA mRNA induction in response to agents elevating intracellular cAMP such as the cAMP analogue 8-bromo-cAMP and the adenylate cyclase-stimulating hormones vasopressin and calcitonin. In contrast, the mutant cells responded to a similar or greater extent than the parental cells in terms of uPA mRNA induction following treatment with the Ca2+/phospholipid-dependent protein kinase activator phorbol 12-myristate 13-acetate (PMA). Elevation of intracellular cAMP was found to induce a translocation of the cAMP-PK C subunit from the perinuclear Golgi region to the nucleus in both parental and mutant cell lines, as shown by immunocytochemical techniques. Results argue for the role of the cAMP-PK C subunit activity and possibly nuclear translocation of the C subunit in cAMP-mediated uPA induction, which is mechanistically distinct from the PMA-stimulated response.
Pearson
D
D
Friedrich Miescher-Institut, Basel, Switzerland.
Nigg
E A
EA
Nagamine
Y
Y
Jans
D A
DA
Hemmings
B A
BA
D000818:Animals; D001692:Biological Transport; D002460:Cell Line; D004847:Epithelial Cells; D004848:Epithelium / Q000378:metabolism; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D007150:Immunohistochemistry; D007668:Kidney / Q000166:cytology / Q000378:metabolism*; D009154:Mutation; D010960:Plasminogen Activators / Q000235:genetics*; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D013347:Subcellular Fractions / Q000737:chemistry; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D015533:Transcriptional Activation; D014568:Urokinase-Type Plasminogen Activator / Q000235:genetics*
D012333:RNA, Messenger; D011494:Protein Kinases; D010960:Plasminogen Activators; D014568:Urokinase-Type Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate