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Mice lacking myosin IXb, an inflammatory bowel disease susceptibility gene, have impaired intestinal barrier function and superficial ulceration in the ileum
Author(s) -
Hegan Peter S.,
Chandhoke Surjit K.,
Barone Christina,
Egan Marie,
Bähler Martin,
Mooseker Mark S.
Publication year - 2016
Publication title -
cytoskeleton
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 86
eISSN - 1949-3592
pISSN - 1949-3584
DOI - 10.1002/cm.21292
Subject(s) - biology , ileum , inflammatory bowel disease , barrier function , function (biology) , gene , myosin , disease , immunology , inflammatory bowel diseases , genetics , microbiology and biotechnology , pathology , endocrinology , medicine
Genetic studies have implicated MYO9B , which encodes myosin IXb (Myo9b), a motor protein with a Rho GTPase activating domain (RhoGAP), as a susceptibility gene for inflammatory bowel disease (IBD). Moreover, we have recently shown that knockdown of Myo9b in an intestinal epithelial cell line impairs wound healing and barrier function. Here, we investigated whether mice lacking Myo9b have impaired intestinal barrier function and features of IBD. Myo9b knock out (KO) mice exhibit impaired weight gain and fecal occult blood (indicator of gastrointestinal bleeding), and increased intestinal epithelial cell apoptosis could be detected along the entire intestinal axis. Histologic analysis revealed intestinal mucosal damage, most consistently observed in the ileum, which included superficial ulceration and neutrophil infiltration. Focal lesions contained neutrophils and ultrastructural examination confirmed epithelial discontinuity and the deposition of extracellular matrix. We also observed impaired mucosal barrier function in KO mice. Transepithelial electrical resistance of KO ileum is >3 fold less than WT ileum. The intestinal mucosa is also permeable to high molecular weight dextran, presumably due to the presence of mucosal surface ulcerations. There is loss of tight junction‐associated ZO‐1, decreased lateral membrane associated E‐cadherin, and loss of terminal web associated cytokeratin filaments. Consistent with increased Rho activity in the KO, there is increased subapical expression of activated myosin II (Myo2) based on localization of phosphorylated Myo2 regulatory light chain. Except for a delay in disease onset in the KO, no difference in dextran sulfate sodium‐induced colitis and lethality was observed between wild‐type and Myo9b KO mice. © 2016 Wiley Periodicals, Inc.