Localization of the 7H6 antigen at tight junctions correlates with the paracellular barrier function of MDCK cells.
An important function of the tight junction is to act as a selective barrier to ions and small molecules, although no molecule responsible for the barrier function has been identified. Here we report evidence that the localization of the 7H6 tight junction-associated antigen identified in our laboratory at tight junctions correlates with the barrier function of MDCK cells. MDCK cells in a confluent monolayer possessed a polarized morphology, having an apical plasma membrane and a basolateral membrane, which is separated from the former by tight junctions. MDCK cells expressed both ZO-1 and 7H6 antigen at tight junctions, which maintain a tight barrier as determined by resistance to lanthanum permeation and high transepithelial electrical resistance (TER, 1500 ohm-cm2). The 7H6 antigen disappeared as tight junctions became permeable to lanthanum with a decrease in TER (below 100 ohm-cm2) due to treatment with metabolic inhibitors (10 microns antimycin A and 10 mM 2-deoxyglucose) for 30 min, while leaving ZO-1 at the cell border. The 7H6 antigen appeared at tight junctions again as TER recovered to a high level (1500 ohm-cm2) within 3 h after withdrawal of metabolic inhibitors. In addition, we found that 7H6 antigen is a phosphorylated protein and that phosphorylation is closely related to the localization of 7H6 antigen in the area of tight junctions.
Zhong
Y
Y
Department of Pathology, Sapporo Medical University School of Medicine, Japan.
Enomoto
K
K
Isomura
H
H
Sawada
N
N
Minase
T
T
Oyamada
M
M
Konishi
Y
Y
Mori
M
M
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D000968:Antimycin A / Q000494:pharmacology; D001692:Biological Transport; D002463:Cell Membrane Permeability / Q000187:drug effects; D002478:Cells, Cultured; D003847:Deoxyglucose / Q000494:pharmacology; D004285:Dogs; D017097:Electric Impedance; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000276:immunology; D005455:Fluorescent Antibody Technique; D007365:Intercellular Junctions / Q000187:drug effects / Q000276:immunology* / Q000648:ultrastructure; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000276:immunology*; D007811:Lanthanum / Q000378:metabolism; D008565:Membrane Proteins / Q000302:isolation & purification*; D010750:Phosphoproteins / Q000302:isolation & purification*; D010766:Phosphorylation; D013997:Time Factors; D062826:Zonula Occludens-1 Protein
D008565:Membrane Proteins; D010750:Phosphoproteins; D062826:Zonula Occludens-1 Protein; C089734:antigen 7H6; D000968:Antimycin A; D007811:Lanthanum; D000255:Adenosine Triphosphate; D003847:Deoxyglucose