Protein kinase-A-mediated secretion of mucin from human colonic epithelial cells.
Both Ca(2+)- and cAMP-mediated second messenger cascades acutely regulate mucin secretion from human colonic epithelial cells. To better understand the cAMP-dependent regulation of mucin secretion we have characterized the complement of cAMP-dependent protein kinase (PKA) isoforms in mucus-secreting T84 cells, and determined which of these isoforms is responsible for agonist-stimulated mucin secretion. Our results show the presence of both type I and type II PKA in cells that also contain large mucin granules. Forskolin caused a rapid and sustained increase in PKA activity that reached a maximum 5-10 min following its addition. Secretion of mucin was detected 15 min following exposure to forskolin, and continued to increase for a further 15 min before reaching a plateau. Mucin secretion was also measured in the presence of combinations of site-selective cAMP analog pairs, which preferentially activate either type I or type II PKA. Similar levels of mucin secretion were observed for both type I and type II PKA-selective analog pairs. Subsequent addition of forskolin was unable to further increase mucin secretion. Thus, activation of either type I or type II PKA is able to maximally stimulate secretion of mucins from T84 human colonic epithelial cells.
Bradbury
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Cystic Fibrosis Research Center, Department of Cell Biology and Physiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. nabrad@pitt.edu
D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D003106:Colon / Q000378:metabolism*; D000242:Cyclic AMP / Q000378:metabolism; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D009077:Mucins / Q000378:metabolism*; D015398:Signal Transduction
D009077:Mucins; D005576:Colforsin; D000242:Cyclic AMP; D054746:Cyclic AMP-Dependent Protein Kinase Type II; D017868:Cyclic AMP-Dependent Protein Kinases; D002118:Calcium