Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters

Ben Quan Shen, Roger A. Barthelson, William Skach, Dieter C. Gruenert, Elliott Sigal, Randall J. Mrsny, Jonathan H. Widdicombe

Research output: Contribution to journalArticle

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Abstract

In T84 cells, we investigated how stimulation of protein kinase C leads to an inhibition of cAMP-dependent chloride secretion. Specifically, we tested the hypothesis that the inhibition was caused by loss of the cystic fibrosis transmembrane regulator (CFTR), an apical membrane chloride channel. As described by others (Trapnell, B. C., Zeitlin, P. L., Chu, C.-S., Yoshimura, K., Nakamura, H., Guggino, W. B., Bargon, J., Banks, T. C., Dalemans, W., Pavirani, A., Lecocq, J.-P., and Crystal, R. G. (1991) J. Biol. Chem. 266, 10319-10323), we found that treatment with the phorbol ester, phorbol myristate acetate (PMA), reduced CFTR mRNA levels by ∼80% with a t1/2 of ∼2 h. Chloride secretion, measured as forskolin-induced short circuit current, was also abolished by PMA with a t1/2 of ∼2 h. Levels of mature glycosylated CFTR measured by Western blotting also declined to 50 ± 8% (n = 7) of control after a 12-h PMA treatment. However, a 12-h exposure to PMA did not affect the forskolin-stimulated efflux of 125I into high potassium medium, a measure of apical membrane CFTR activity. We conclude that increased turnover of apical membrane CFTR in PMA-treated cells compensates for the decline in anion channel numbers. By contrast to its lack of effect on 125I effluxes, PMA reduced the cAMP-induced increase in 86Rb efflux, suggesting that it inhibits chloride secretion mainly by an action on basolateral potassium channels.

Original languageEnglish (US)
Pages (from-to)19070-19075
Number of pages6
JournalJournal of Biological Chemistry
Volume268
Issue number25
StatePublished - Sep 5 1993
Externally publishedYes

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Phorbol Esters
Tetradecanoylphorbol Acetate
Chlorides
Cystic Fibrosis
Colforsin
Membranes
Chloride Channels
Potassium Channels
Ion Channels
Short circuit currents
Protein Kinase C
Anions
Potassium
Western Blotting
Cells
Messenger RNA
Crystals

ASJC Scopus subject areas

  • Biochemistry

Cite this

Shen, B. Q., Barthelson, R. A., Skach, W., Gruenert, D. C., Sigal, E., Mrsny, R. J., & Widdicombe, J. H. (1993). Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters. Journal of Biological Chemistry, 268(25), 19070-19075.

Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters. / Shen, Ben Quan; Barthelson, Roger A.; Skach, William; Gruenert, Dieter C.; Sigal, Elliott; Mrsny, Randall J.; Widdicombe, Jonathan H.

In: Journal of Biological Chemistry, Vol. 268, No. 25, 05.09.1993, p. 19070-19075.

Research output: Contribution to journalArticle

Shen, BQ, Barthelson, RA, Skach, W, Gruenert, DC, Sigal, E, Mrsny, RJ & Widdicombe, JH 1993, 'Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters', Journal of Biological Chemistry, vol. 268, no. 25, pp. 19070-19075.
Shen BQ, Barthelson RA, Skach W, Gruenert DC, Sigal E, Mrsny RJ et al. Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters. Journal of Biological Chemistry. 1993 Sep 5;268(25):19070-19075.
Shen, Ben Quan ; Barthelson, Roger A. ; Skach, William ; Gruenert, Dieter C. ; Sigal, Elliott ; Mrsny, Randall J. ; Widdicombe, Jonathan H. / Mechanism of inhibition of cAMP-dependent epithelial chloride secretion by phorbol esters. In: Journal of Biological Chemistry. 1993 ; Vol. 268, No. 25. pp. 19070-19075.
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abstract = "In T84 cells, we investigated how stimulation of protein kinase C leads to an inhibition of cAMP-dependent chloride secretion. Specifically, we tested the hypothesis that the inhibition was caused by loss of the cystic fibrosis transmembrane regulator (CFTR), an apical membrane chloride channel. As described by others (Trapnell, B. C., Zeitlin, P. L., Chu, C.-S., Yoshimura, K., Nakamura, H., Guggino, W. B., Bargon, J., Banks, T. C., Dalemans, W., Pavirani, A., Lecocq, J.-P., and Crystal, R. G. (1991) J. Biol. Chem. 266, 10319-10323), we found that treatment with the phorbol ester, phorbol myristate acetate (PMA), reduced CFTR mRNA levels by ∼80{\%} with a t1/2 of ∼2 h. Chloride secretion, measured as forskolin-induced short circuit current, was also abolished by PMA with a t1/2 of ∼2 h. Levels of mature glycosylated CFTR measured by Western blotting also declined to 50 ± 8{\%} (n = 7) of control after a 12-h PMA treatment. However, a 12-h exposure to PMA did not affect the forskolin-stimulated efflux of 125I into high potassium medium, a measure of apical membrane CFTR activity. We conclude that increased turnover of apical membrane CFTR in PMA-treated cells compensates for the decline in anion channel numbers. By contrast to its lack of effect on 125I effluxes, PMA reduced the cAMP-induced increase in 86Rb efflux, suggesting that it inhibits chloride secretion mainly by an action on basolateral potassium channels.",
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AU - Sigal, Elliott

AU - Mrsny, Randall J.

AU - Widdicombe, Jonathan H.

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