Introduction of DNA enzyme for Egr-1 into tubulointerstitial fibroblasts by electroporation reduced interstitial alpha-smooth muscle actin expression and fibrosis in unilateral ureteral obstruction (UUO) rats.

Abstract

The phenotypic alteration of interstitial fibroblasts into 'myofibroblasts', acquiring characteristics of both fibroblasts and smooth muscle cells is a key event in the formation of tubulointerstitial fibrosis. The up-regulation of the early growth response gene 1 (Egr-1) preceded the increased interstitial expression of alpha-smooth muscle actin (alphaSMA), a marker of phenotypic changes, in obstructed kidney, a model of interstitial fibrosis. To target Egr-1 expression in the interstitium of obstructed kidneys, we introduced a DNA enzyme for Egr-1 (ED5) or scrambled DNA (SCR) into interstitial fibroblasts by electroporation-mediated gene transfer. Northern blot analysis confirmed an increase in the cortical mRNA expression of Egr-1 in the obstructed kidneys from untreated or SCR-treated rats, while ED5 transfection blocked Egr-1 expression with a concomitant reduction in TGF-beta, alphaSMA and type I collagen mRNA expression. Consequently, ED5 inhibited interstitial fibrosis. In conclusion, electroporation-mediated retrograde gene transfer can be an ideal vehicle into interstitial fibroblasts, and molecular intervention of Egr-1 in the interstitium may become a new therapeutic strategy for interstitial fibrosis.