AJP - Cell Physiology, Vol 266, Issue 3 C661-C668, Copyright © 1994 by American Physiological Society

ARTICLES

Forskolin- but not ionomycin-evoked Cl- secretion in colonic epithelia depends on intact microtubules

C. M. Fuller, R. J. Bridges and D. J. Benos
Department of Physiology and Biophysics, University of Alabama at Birmingham 35294.

Several transport proteins are known to be trafficked to the cell membrane in response to appropriate secretagogues. In several cases, the response has been shown to be dependent on the cytoskeleton. We tested the hypothesis that the forskolin- and/or ionomycin-sensitive Cl- secretory response in colonic epithelia is dependent on an intact cytoskeleton. Using 125I- efflux as an assay for Cl- transport in the colonic epithelial cell line T84, we found that preincubation of the tissue for 3 h with either of two inhibitors of microtubule polymerization, nocodazole or colchicine, disrupted the cellular tubulin architecture and also reduced the forskolin- but not the ionomycin-evoked I- efflux. In contrast, brief exposure (4 min) to nocodazole was without effect on the forskolin-sensitive efflux, suggesting that the drug is not acting to block the stimulus-response pathway. An inactive structural analogue of colchicine, beta-lumicolchicine, had no inhibitory effect on either the forskolin-sensitive efflux or on microtubular structure. In a second model of Cl- secretion, the stripped rat colon, both colchicine and nocodazole reduced the forskolin-dependent short-circuit current by an average of 30-40%, suggesting a similar mechanism for insertion of Cl- channels into the plasma membrane. These findings suggest that the Cl- secretory response is dependent on microtubules and has a physiological role in the adenosine 3',5'-cyclic monophosphate-dependent, but not the Ca(2+)-dependent, Cl- secretion in colonic epithelia.

This article has been cited by other articles:

				N. A. Ameen, C. Marino, and P. J. I. Salas cAMP-dependent exocytosis and vesicle traffic regulate CFTR and fluid transport in rat jejunum in vivo Am J Physiol Cell Physiol, February 1, 2003; 284(2): C429 - C438. [Abstract] [Full Text] [PDF]

				A. M. Gomez, B. G. Kerfant, and G. Vassort Microtubule Disruption Modulates Ca2+ Signaling in Rat Cardiac Myocytes Circ. Res., January 7, 2000; 86(1): 30 - 36. [Abstract] [Full Text] [PDF]

				Z. Li, E. Elliott, J. Payne, J. Isaacs, P. Gunning, and E. V. O'loughlin Shiga Toxin-Producing Escherichia coli Can Impair T84 Cell Structure and Function without Inducing Attaching/Effacing Lesions Infect. Immun., November 1, 1999; 67(11): 5938 - 5945. [Abstract] [Full Text] [PDF]

				D. Merlin, L. Jiang, G. R. Strohmeier, A. Nusrat, S. L. Alper, W. I. Lencer, and J. L. Madara Distinct Ca2+- and cAMP-dependent anion conductances in the apical membrane of polarized T84 cells Am J Physiol Cell Physiol, August 1, 1998; 275(2): C484 - C495. [Abstract] [Full Text] [PDF]

				R. G. Morris, A. Tousson, D. J. Benos, and J. A. Schafer Microtubule disruption inhibits AVT-stimulated Cl- secretion but not Na+ reabsorption in A6 cells Am J Physiol Renal Physiol, February 1, 1998; 274(2): F300 - F314. [Abstract] [Full Text] [PDF]