Effect of modulation of protein kinase C on the cAMP-dependent chloride conductance in T84 cells.
The regulation of chloride conductance was investigated in the T84 human colon carcinoma cell line by the quenching of the fluorescent probe 6-methoxy-N-(3-sulfopropyl)quinolinium. The permeable cAMP analog 8-Br-cAMP (100 microM) and the calcium ionophore ionomycin (1 microM) activate a chloride conductance. A prolonged (4 h) preincubation of cells with phorbol 12-myristate 13-acetate (100 nM) or with the diacylglycerol analog 1-oleoyl-2-acetyl-glycerol (100 microM): (i) down-modulates to almost zero the protein kinase C activity in the membranes; (ii) inhibits the activation of the chloride conductance mediated by 8-Br-cAMP but not by calcium; (iii) reduces the mRNA without changing the expression of the protein product of the cystic fibrosis gene. The data suggest that PKC is essential for the activation of the cAMP-dependent chloride conductance in T84 cells.
Dechecchi
M C
MC
Centro Fibrosi Cistica, Ospedale Civile Maggiore, Verona, Italy.
Rolfini
R
R
Tamanini
A
A
Gamberi
C
C
Berton
G
G
Cabrini
G
G
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D001692:Biological Transport; D018118:Chloride Channels; D002712:Chlorides / Q000378:metabolism*; D003110:Colonic Neoplasms; D000242:Cyclic AMP / Q000494:pharmacology*; D003550:Cystic Fibrosis / Q000378:metabolism*; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D004075:Diglycerides / Q000494:pharmacology; D015536:Down-Regulation; D004553:Electric Conductivity; D005453:Fluorescence; D005456:Fluorescent Dyes; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D008565:Membrane Proteins / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D011806:Quinolinium Compounds; D012333:RNA, Messenger / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014407:Tumor Cells, Cultured
C505032:CFTR protein, human; D018118:Chloride Channels; D002712:Chlorides; D004075:Diglycerides; D005456:Fluorescent Dyes; D008565:Membrane Proteins; D011806:Quinolinium Compounds; D012333:RNA, Messenger; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D015124:8-Bromo Cyclic Adenosine Monophosphate; D015759:Ionomycin; C052335:6-methoxy-N-(3-sulfopropyl)quinolinium; C038237:1-oleoyl-2-acetylglycerol; D000242:Cyclic AMP; D011494:Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate