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Mol Biol Cell. 2013 Sep;24(18):2849-60. doi: 10.1091/mbc.E13-06-0298. Epub 2013 Jul 24.

JAM-A associates with ZO-2, afadin, and PDZ-GEF1 to activate Rap2c and regulate epithelial barrier function.

Author information

1
Department of Pathology, Emory University School of Medicine, Atlanta, GA 30306 Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30306 Emory Rollins School of Public Health, Atlanta, GA 30306 Interfaculty Institute of Biochemistry, University of Tübingen, D-72076 Tübingen, Germany Department of Pediatrics and Pathology, Vanderbilt University School of Medicine, Nashville, TN 37230 Departments of Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37230 Elizabeth B. Lamb Center for Pediatric Research, Vanderbilt University School of Medicine, Nashville, TN 37230.

Abstract

Intestinal barrier function is regulated by epithelial tight junctions (TJs), structures that control paracellular permeability. Junctional adhesion molecule-A (JAM-A) is a TJ-associated protein that regulates barrier; however, mechanisms linking JAM-A to epithelial permeability are poorly understood. Here we report that JAM-A associates directly with ZO-2 and indirectly with afadin, and this complex, along with PDZ-GEF1, activates the small GTPase Rap2c. Supporting a functional link, small interfering RNA-mediated down-regulation of the foregoing regulatory proteins results in enhanced permeability similar to that observed after JAM-A loss. JAM-A-deficient mice and cultured epithelial cells demonstrate enhanced paracellular permeability to large molecules, revealing a potential role of JAM-A in controlling perijunctional actin cytoskeleton in addition to its previously reported role in regulating claudin proteins and small-molecule permeability. Further experiments suggest that JAM-A does not regulate actin turnover but modulates activity of RhoA and phosphorylation of nonmuscle myosin, both implicated in actomyosin contraction. These results suggest that JAM-A regulates epithelial permeability via association with ZO-2, afadin, and PDZ-GEF1 to activate Rap2c and control contraction of the apical cytoskeleton.

PMID:
23885123
PMCID:
PMC3771947
DOI:
10.1091/mbc.E13-06-0298
[Indexed for MEDLINE]
Free PMC Article

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