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Protein kinase C activation downregulates the expression and function of the basolateral Na + /K + /2Cl − cotransporter
Author(s) -
Farokhzad Omid C.,
Sagar G.D. Vivek,
Mun Edward C.,
Sicklick Jason K.,
Lotz Margaret,
Smith Jeremy A.,
Song Jaekyung C.,
O'Brien Timothy C.,
Sharma C. Pal,
Kinane T. Bernard,
Hodin Richard A.,
Matthews Jeffrey B.
Publication year - 1999
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/(sici)1097-4652(199912)181:3<489::aid-jcp13>3.0.co;2-7
Subject(s) - protein kinase c , messenger rna , cyclic adenosine monophosphate , protein kinase a , phorbol , biology , cotransporter , chemistry , microbiology and biotechnology , signal transduction , kinase , biochemistry , receptor , gene , organic chemistry , sodium
The basolateral Na + /K + /2Cl − cotransporter (NKCC1) has been shown to be an independent regulatory site for electrogenic Cl − secretion. The proinflammatory phorbol ester, phorbol 12‐myristate 13‐acetate (PMA), which activates protein kinase C (PKC), inhibits basal and cyclic adenosine monophosphate (cAMP)‐stimulated NKCC1 activity in T84 intestinal epithelial cells and decreases the steady state levels of NKCC1 mRNA in a time‐ and dose‐dependent manner. The levels of NKCC1 protein also fall in accordance with the NKCC1 mRNA transcript and these levels are unaffected by 4α‐phorbol, which does not activate PKC. Inhibition of maximal (cAMP‐stimulated) NKCC1 functional activity by PMA was first detected by 1 h, whereas decreases in the steady state levels of NKCC1 mRNA were not detectable until 4 h. NKCC1 mRNA expression recovers toward control levels with extended treatment of cells with PMA suggesting that the PMA effects on NKCC1 expression are mediated through activation of PKC. Although NKCC1 mRNA and protein levels return to control values after extended PMA exposure, NKCC1 functional activity does not recover. Immunofluorescence imaging suggest that the absence of functional recovery is due to failure of newly synthesized NKKC1 protein to reach the cell surface. We conclude that NKCC1 has the capacity to be regulated at the level of de novo expression by PKC, although decreased NKCC1 expression alone cannot account for either early or late loss of NKCC1 function. J. Cell. Physiol. 181:489–498, 1999. © 1999 Wiley‐Liss, Inc.