Activation of protein kinase C attenuates prostaglandin E2 responses in a colonic cell line

We examined the possibility that the protein kinase C pathway may interact with the adenosine 3',5'-cyclic monophosphate (cAMP) pathway in intestinal epithelium by studying the influence of phorbol esters on the response to prostaglandin E2 (PGE2) in a colonic epithelial cell line. Pretrea...

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Published inThe American journal of physiology Vol. 255; no. 1 Pt 1; p. G27
Main Authors Warhurst, G, Higgs, N B, Lees, M, Tonge, A, Turnberg, L A
Format Journal Article
LanguageEnglish
Published United States 01.07.1988
Subjects
Animals
Bucladesine - pharmacology
Cell Line
Cells, Cultured
Colforsin - pharmacology
Colon - drug effects
Cyclic AMP - metabolism
Dimethyl Sulfoxide - pharmacology
Dinoprostone
Enzyme Activation
Phorbol 12,13-Dibutyrate
Phorbol Esters - pharmacology
Prostaglandins E - pharmacology
Protein Kinase C - metabolism
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Summary:We examined the possibility that the protein kinase C pathway may interact with the adenosine 3',5'-cyclic monophosphate (cAMP) pathway in intestinal epithelium by studying the influence of phorbol esters on the response to prostaglandin E2 (PGE2) in a colonic epithelial cell line. Pretreatment of T84 cells with 4 beta-phorbol 12,13-dibutyrate (PDB) markedly attenuated the rise in short-circuit current provoked by PGE2, a receptor-mediated cAMP agonist. The EC50 of this effect was 52 nM PDB with a half time of 4-6 min. The responses to nonreceptor-mediated agonists, forskolin and dibutyryl cAMP, were unaffected by phorbol ester. PDB also reduced the ability of PGE2 to stimulate adenylate cyclase activity in these cells. The accumulation of cAMP in response to PGE2 was inhibited by PDB (EC50 38 nM), an effect mimicked by the diacylglycerol analogue 1-oleoyl-2-acetyl-sn-glycerol. In addition, PGE2 stimulation of adenylate cyclase in membranes from PDB-treated cells was reduced by 30-40%. Inhibition was not mediated via the catalytic or regulatory subunit of the adenylate cyclase, implying an action involving desensitization of PGE2 receptors. These results provide evidence of a complex interrelationship between protein kinase C- and cAMP-mediated pathways that might be important in regulating the cellular response to secretagogues.
ISSN:0002-9513
DOI:10.1152/ajpgi.1988.255.1.G27