FIG 4.

α4 knockout disrupts the intestinal epithelial barrier function in vivo and in vitro. (A) Immunoblots of the TJs claudin-1, claudin-3, ZO-1, and occludin; the AJ E-cadherin; and the RBPs HuR and CUGBP1 in the small intestinal mucosa obtained from littermate and IE-HuR^−/− mice. (B) Changes in gut permeability in mice shown in panel A. FITC-dextran was given orally, and blood samples were collected 4 h thereafter for measurement. The values are means and SEM of data from 5 animals. *, P < 0.05 compared with littermates. (C) Immunoblots of intercellular junction proteins and RBPs in cultured IECs. Differentiated IEC-Cdx2L1 cells were transfected with C-siRNA or siα4, and cell lysates were harvested 48 h thereafter. (D) Epithelial barrier function as indicated by changes in TEER and FITC-dextran paracellular permeability in the cells shown in panel C. TEER assays were performed on 12-mm Transwell filters; paracellular permeability was assayed by using the membrane-impermeable trace molecule FITC-dextran, which was added to the medium in the insert part of the Transwell plate. The values are means and SEM of data from six samples. *, P < 0.05 compared with C-siRNA.