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Am J Physiol Gastrointest Liver Physiol 292: G124-G133, 2007. First published September 7, 2006; doi:10.1152/ajpgi.00297.2006
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This Article Free upon publication Full Text Full Text (PDF) All Versions of this Article: 292/1/G124    most recent 00297.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Rajasekaran, S. A. Articles by Rajasekaran, A. K. Search for Related Content PubMed PubMed Citation Articles by Rajasekaran, S. A. Articles by Rajasekaran, A. K.

MUCOSAL BIOLOGY

Na-K-ATPase regulates tight junction permeability through occludin phosphorylation in pancreatic epithelial cells

¹Department of Pathology and Laboratory Medicine, ²Department of Biological Chemistry, ³Molecular Biology Institute, ⁴Jonsson Comprehensive Cancer Center, David Geffen School of Medicine, University of California, Los Angeles, California; and ⁵Molecular Pathology Unit, Massachusetts General Hospital East, Charlestown, Massachusetts

Submitted 6 July 2006 ; accepted in final form 28 August 2006

Tight junctions are crucial for maintaining the polarity and vectorial transport functions of epithelial cells. We and others have shown that Na-K-ATPase plays a key role in the organization and permeability of tight junctions in mammalian cells and analogous septate junctions in Drosophila. However, the mechanism by which Na-K-ATPase modulates tight junctions is not known. In this study, using a well-differentiated human pancreatic epithelial cell line HPAF-II, we demonstrate that Na-K-ATPase is present at the apical junctions and forms a complex with protein phosphatase-2A, a protein known to be present at tight junctions. Inhibition of Na-K-ATPase ion transport function reduced protein phosphatase-2A activity, hyperphosphorylated occludin, induced rearrangement of tight junction strands, and increased permeability of tight junctions to ionic and nonionic solutes. These data suggest that Na-K-ATPase is required for controlling the tight junction gate function.

Na-K-ATPase ₁-subunit; Na-K-ATPase ₁-subunit; protein phosphatase-2A; pancreas

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