Decrease in claudin‐2 expression enhances cell migration in renal epithelial madin–darby canine kidney cells

Abstract

Migration of renal epithelial cells increases after renal tubular damage, but its mechanism has not been clarified in detail. Hyperosmotic stress increased a cellular injury concomitant with a decrease in mRNA and protein expression of claudin-2 in renal tubular epithelial Madin-Darby canine kidney cells. We hypothesized that claudin-2 is involved in the regulation of cell migration. To knockdown claudin-2 expression, we made the cells expressing doxycycline-inducible claudin-2 shRNA vector. Claudin-2 knockdown affected neither the endogenous expression levels of claudin-1, -3, -4, and -7 nor the Triton X-100 solubility of these claudins. Transepithelial electrical resistance was increased by claudin-2 knockdown without affecting permeability to FITC-dextran (4,000 Da). BrdU incorporation assay and cell counting revealed that cell proliferation and viability are unaffected by claudin-2 knockdown. In the wound-healing assay, the recovery rate of wound area was increased by claudin-2 knockdown. The mRNA expression and activity of matrix metalloproteinase-9 (MMP-9) were increased by claudin-2 knockdown. A selective MMP-9 inhibitor suppressed cell migration in the claudin-2 knockdown cells. Hyperosmotic stress increased the expression and activity of MMP-9, which were inhibited by claudin-2 overexpression. These results suggest that the decrease in claudin-2 expression enhances cell migration mediated by the increase in the expression and activity of MMP-9.