Affiliation:
1. Section of Digestive and Liver Diseases, Department of Medicine, University of Illinois and West Side Veterans Affairs Medical Center, Chicago, Illinois 60612
Abstract
The basally located actin cytoskeleton has been demonstrated previously to regulate Cl−secretion from intestinal epithelia via its effects on the Na+-K+-2Cl−cotransporter (NKCC1). In nontransporting epithelia, inhibition of myosin light chain kinase (MLCK) prevents cell-shrinkage-induced activation of NKCC1. The aim of this study was to investigate the role of myosin in the regulation of secretagogue-stimulated Cl− secretion in intestinal epithelia. The human intestinal epithelial cell line T84 was used for these studies. Prevention of myosin light chain phosphorylation with the MLCK inhibitor ML-9 or ML-7 and inhibition of myosin ATPase with butanedione monoxime (BDM) attenuated cAMP but not Ca2+-mediated Cl− secretion. Both ML-9 and BDM diminished cAMP activation of NKCC1. Neither apical Cl− channel activity, basolateral K+ channel activity, nor Na+-K+-ATPase were affected by these agents. Cytochalasin D prevented such attenuation. cAMP-induced rearrangement of basal actin microfilaments was prevented by both ML-9 and BDM. The phosphorylation of mosin light chain and subsequent contraction of basal actin-myosin bundles are crucial to the cAMP-driven activation of NKCC1 and subsequent apical Cl− efflux.
Publisher
American Physiological Society
Cited by
44 articles.
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