Dual role for protein kinase C alpha as a regulator of ion secretion in the HT29cl.19A human colonic cell line.
The involvement of protein kinase C (PKC) in the regulation of intestinal ion secretion was studied in polarized monolayers of the HT29cl.19A human colon carcinoma cell line. Carbachol, phorbol esters [PMA (phorbol 12-myristate 13-acetate) and PDB (phorbol 12,13-dibutyrate)] and 8-bromo cyclic AMP (8-Br-cAMP) induced Cl secretion, as measured by a rise in the short-circuit current (ISC). The electrical response to carbachol coincided with a transient translocation of PKC alpha from the soluble to the particulate fraction. The carbachol-, PDB- and 8-Br-cAMP-induced ISC responses were inhibited by pretreatment of the cells with PMA (0.5 microM) for 2 h, a time period in which PKC alpha, beta 1 and gamma levels were not changed. As shown by 86Rb+ and 125I- efflux studies, the main targets for this inhibition were basolateral K+ transporters rather than apical Cl- channels. Prolonged exposure to PMA (24 h) led to a 60% recovery of the 8-Br-cAMP response, but not of the carbachol- or PDB-provoked secretion. As shown by immunoblotting with PKC-isoenzyme-specific antisera, the recovery of the 8-Br-cAMP response coincided with the down-regulation of PKC alpha, whereas the levels of PKC beta 1 and gamma were unmodified. These results suggest that PKC alpha, but not PKC beta 1 or gamma, is involved in both acute stimulation and chronic inhibition of ion secretion in the HT29cl.19A colonic cell line.
van den Berghe
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N
Department of Biochemistry, Erasmus University Rotterdam, The Netherlands.
Vaandrager
A B
AB
Bot
A G
AG
Parker
P J
PJ
de Jonge
H R
HR
D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000838:Anions; D001692:Biological Transport; D015153:Blotting, Western; D002217:Carbachol / Q000494:pharmacology; D002412:Cations; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003106:Colon / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004591:Electrophoresis, Polyacrylamide Gel; D006801:Humans; D007454:Iodides / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D010703:Phorbol Esters / Q000494:pharmacology; D011493:Protein Kinase C / Q000378:metabolism*; D012413:Rubidium / Q000378:metabolism*
D000838:Anions; D002412:Cations; D007454:Iodides; D007527:Isoenzymes; D010703:Phorbol Esters; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D002217:Carbachol; D011493:Protein Kinase C; D012413:Rubidium