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J. Biol. Chem. 284 (41): 27952-27963

© 2009 by The American Society for Biochemistry and Molecular Biology, Inc.

AMP-activated Protein Kinase Mediates the Interferon-{gamma}-induced Decrease in Intestinal Epithelial Barrier Function*

Michael Scharl, Gisela Paul, Kim E. Barrett, , and Declan F. McCole1

From the Department of Medicine, University of California, San Diego, School of Medicine, La Jolla, California 92093

ABSTRACT Back to Top

Abstract: Impaired epithelial barrier function plays a crucial role in the pathogenesis of inflammatory bowel disease. Elevated levels of the pro-inflammatory cytokine, interferon-{gamma} (IFN{gamma}), are believed to be prominently involved in the pathogenesis of Crohn disease. Treatment of T84 intestinal epithelial cells with IFN{gamma} severely impairs their barrier properties measured as transepithelial electrical resistance (TER) or permeability and reduces the expression of tight junction proteins such as occludin and zonula occludens-1 (ZO-1). However, little is known about the signaling events that are involved. The cellular energy sensor, AMP-activated protein kinase (AMPK), is activated in response to cellular stress, as occurs during inflammation. The aim of this study was to investigate a possible role for AMPK in mediating IFN{gamma}-induced effects on the intestinal epithelial barrier. We found that IFN{gamma} activates AMPK by phosphorylation, independent of intracellular energy levels. Inhibition of AMPK prevents, at least in part, the IFN{gamma}-induced decrease in TER. Furthermore, AMPK knockdown prevented the increased epithelial permeability, the decreased TER, and the decrease in occludin and ZO-1 caused by IFN{gamma} treatment of T84 cells. However, AMPK activity alone was not sufficient to cause alterations in epithelial barrier function. These data show a novel role for AMPK, in concert with other signals induced by IFN{gamma}, in mediating reduced epithelial barrier function in a cell model of chronic intestinal inflammation. These findings may implicate AMPK in the pathogenesis of chronic intestinal inflammatory conditions, such as inflammatory bowel disease.

Received for publication July 20, 2009. Revision received August 3, 2009.

1 To whom correspondence should be addressed: Division of Gastroenterology, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92093-0063. Tel.: 858-534-2794; Fax: 858-534-3338; E-mail: dmccole{at}ucsd.edu.

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