title: A novel monoclonal antibody against the second extracellular loop of occludin disrupts epithelial cell polarity.
abstract: The tight junction (TJ) regulates epithelial cell polarity and paracellular permeability. In the present study, to investigate whether the second extracellular loop of occludin affects the localization of carcinoembryonic antigen (CEA) and CD26 expressed on apical membranes, and the fence function of the TJ, the human intestinal epithelial cell line T84 was treated with the monoclonal anti-occludin antibody (MAb) 1H8, corresponding to the second extracellular loop of occludin. In T84 cells treated with MAb 1H8, occludin disappeared, and CEA and CD26 were observed to diffuse from the apical membrane to the basolateral membrane. Furthermore, a decrease in the fence function of TJ was observed without changes in the TJ strands and barrier function. When T84 cells precultured in low calcium (Ca) medium were recultured in normal Ca medium in the presence of MAb 1H8, recruitment of occludin to the apical-most membranes and recovery in distribution of CEA and CD26 were markedly retarded compared with the control. These results suggested that MAb 1H8 against the second extracellular loop of occludin selectively affected formation of the apical/basolateral intramembrane diffusion barrier and that the second extracellular loop of occludin plays a crucial role in the maintenance of epithelial cell polarity by the TJ.
authors: Department of Pathology, Sapporo Medical University School of Medicine, S1, W17, Sapporo 060-8556, Japan.
authors: Yuichi
authors: Y
authors: Tokunaga
authors: Takashi
authors: T
authors: Kojima
authors: Makoto
authors: M
authors: Osanai
authors: Masaki
authors: M
authors: Murata
authors: Hideki
authors: H
authors: Chiba
authors: Hirotoshi
authors: H
authors: Tobioka
authors: Norimasa
authors: N
authors: Sawada
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D002272:Carcinoembryonic Antigen / Q000378:metabolism; D002460:Cell Line; D016764:Cell Polarity; D004058:Diffusion; D018819:Dipeptidyl Peptidase 4 / Q000378:metabolism; D004847:Epithelial Cells / Q000502:physiology* / Q000648:ultrastructure; D005110:Extracellular Space / Q000378:metabolism; D006801:Humans; D007413:Intestinal Mucosa / Q000166:cytology; D008565:Membrane Proteins / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D008856:Microscopy, Fluorescence; D062793:Occludin; D021381:Protein Transport; D019108:Tight Junctions / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D002272:Carcinoembryonic Antigen; D008565:Membrane Proteins; C568985:OCLN protein, human; D062793:Occludin; D018819:Dipeptidyl Peptidase 4