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Chronic PKC-β activation in HT-29 Cl.19a colonocytes prevents cAMP-mediated ion secretion by inhibiting apical membrane current generation

Chronic PKC-β activation in HT-29 Cl.19a colonocytes prevents cAMP-mediated ion secretion by inhibiting apical membrane current generation

Authors :
James R, Broughman
Limin, Sun
Shahid, Umar
Jason, Scott
Joseph H, Sellin
Andrew P, Morris
Source :
American Journal of Physiology-Gastrointestinal and Liver Physiology. 291:G318-G330
Publication Year :
2006
Publisher :
American Physiological Society, 2006.

Abstract

We investigated the effects of PKC-stimulating 12-deoxyphorbol 13-phenylacetate 20-acetate (DOPPA) and phorbol 12-myristate 13-acetate (PMA) phorbol esters on cAMP-dependent, forskolin (FSK)-stimulated, short-circuit Cl−current ( ISC-cAMP) generation by colonocyte monolayers. These agonists elicited different actions depending on their dose and incubation time; PMA effects at the onset (SCgeneration. DOPPA failed to elicit similar responses. Whereas chronic (24 h) exposure to both agents inhibited FSK-stimulated transcellular and apical membrane ISC-cAMP, the effects of DOPPA were more complex: this conventional PKC-β-specific agonist also stimulated Ba2+-sensitive basolateral membrane-dependent facilitation of transcellular ISC-cAMP. PMA did not elicit a similar phenomenon. Prolonged exposure to high-dose PMA but not DOPPA led to apical membrane ISC-cAMP recovery. Changes in PKC α-, β1-, γ-, and ε-isoform membrane partitioning and expression correlated with these findings. PMA-induced transcellular ISCcorrelated with PKC-α membrane association, whereas low doses of both agents inhibited transcellular and apical membrane ISC-cAMP, increased PKC-β1, decreased PKC-β2membrane association, and caused reciprocal changes in isoform mass. During the apical membrane ISC-cAMP recovery after prolonged high-dose PMA exposure, an almost-complete depletion of cellular PKC-β1and a significant reduction in PKC-ε mass occurred. Thus activated PKC-β1and/or PKC-ε prevented, whereas activated PKC-α facilitated, apical membrane ISC-cAMP. PKC-β-dependent augmentation of transcellular ISC-cAMP at the level of the basolateral membrane demonstrated that transport events with geographically distinct subcellular membranes can be independently regulated by the PKC β-isoform.

Details

ISSN :
15221547 and 01931857
Volume :
291
Database :
OpenAIRE
Journal :
American Journal of Physiology-Gastrointestinal and Liver Physiology
Accession number :
edsair.doi.dedup.....c7e05e1176e5efa7fe746f9e005c5857
Full Text :
https://doi.org/10.1152/ajpgi.00355.2005