Na(+)-K(+)-2Cl- cotransport and Cl- secretion evoked by heat-stable enterotoxin is microfilament dependent in T84 cells

Abstract

We previously reported that adenosine 3',5'-cyclic monophosphate-mediated stimulation of Cl- secretion in the human intestinal epithelial cell line T84 is accompanied by significant remodeling of F-actin and that both the secretory and cytoskeletal responses may be inhibited by phalloidin derivatives, agents that polymerize actin and prevent dynamic reorganization of microfilaments. In contrast, the carbachol-elicited Cl- secretory response (Ca2+ mediated) was not attenuated by phalloidin (J. Clin. Invest. 87: 1903-1909, 1991). In the present study, we examine the effect of phalloidin on the Cl- secretory response elicited by the heat-stable enterotoxin of Escherichia coli (STa), which induces elevations in intracellular guanosine 3',5'-cyclic monophosphate. We find that apical administration of 1 microM STa results in a regionally restricted redistribution of F-actin confined to the basal pole of the cells. In monolayers pretreated with phalloidin, the Cl- secretory response to STa was inhibited by > 60%. Sequential treatment of phalloidin-loaded monolayers with STa followed by carbachol resulted in a synergistic secretory response that was not different from control (unloaded) monolayers. Examination of efflux/uptake through specific membrane transport pathways involved in STa-stimulated Cl- secretion indicated normal activation of apical Cl- and basolateral K+ channels under phalloidin-loaded conditions. The ability of STa-treated monolayers to pump Na+ in an absorptive direction was also unaffected by phalloidin. der phalloidin-loaded conditions, STa-stimulated Na(+)-K(+)-2Cl- cotransporter activity was reduced by approximately 60%, sufficient to account for the observed inhibition of net Cl- secretory response.(ABSTRACT TRUNCATED AT 250 WORDS)

Thromboxane A2, released by the anti‐ tumour drug irinotecan, is a novel stimulator of Cl− secretion in isolated rat colon

“…n.s., not significant (P > 0·05). Greger, 1993;Matthews, Awtrey, Thompson, Hung, Tally & Madara, 1993). The STA2-induced Cl¦ secretion was almost completely inhibited by TXA2 receptor antagonists such as KW_3635 and ONO_3708 (Fig.…”

Pathogenesis of Human Enterovirulent Bacteria: Lessons from Cultured, Fully Differentiated Human Colon Cancer Cell Lines

“…ST increases the net secretory transepithelial volume flux, short-circuit current values, and net secretory Cl flux in fully differentiated T84 cells (599). Na ϩ /K ϩ /2Cl Ϫ cotransport and Cl Ϫ secretion induced by ST have been found to be dependent on the organization of the F-actin cytoskeleton in fully differentiated T84 cells (600). Both LT and STa activate the exocytosis of syntaxin 3, an intestine-specific soluble N-ethylmaleimide-sensitive factor attachment receptor, and a functional CFTR chloride channel that colocalize at the apical domain of fully differentiated Caco-2 BBe clone cells (601).…”

Bacteroides fragilis toxin 2 damages human colonic mucosa in vitro

“…For example, Clostridium difficile toxins A and B cause disruption and condensation of F actin without completely abolishing F actin staining in intestinal epithelial cells27 and fibroblasts 31-33. The zonula occludens toxin of Vibrio cholerae 34 and heat stable enterotoxin of Escherichia coli 35 were also shown to cause rearrangement of F actin in rabbit ileum and T84 cell monolayers, respectively.…”