Gene expression after uninephrectomy in the rat: simultaneous expression of positive and negative growth control elements.

Abstract

Compensatory renal growth after contralateral nephrectomy consists largely of hypertrophy of the renal cortex. The signals initiating compensatory renal growth are as yet unknown. Using a technique of quantitative dot-blot hybridization, we examined the expression of a number of genes after contralateral nephrectomy in the rat in an effort to establish a characteristic "fingerprint" which might shed light on the mechanism of compensatory renal growth. Negative growth control elements, including transcriptional repressors (WT-1, junB, myn, HNF-1, p53, RB, Dr1, gas2, gadd153) were induced 1.7 to 4.7-fold within 1 hour after uninephrectomy, as were positive growth control elements (egr-1, c-jun, cyclin C, cyclin E; 1.9- to 4.2-fold induction). The steady state mRNA levels for heat shock genes hsp70, hsp86 and hsp90 beta, as well as extracellular matrix genes fibronectin and collagen I (alpha 1 chain) were also increased 1 hour after uninephrectomy. In addition, 2 Na(+)-specific exchangers (NHE-1 and Na/Ca) were induced within 1 hour after uninephrectomy. These results suggest the coordinate expression of positive and negative growth control elements early in this physiologic model of organ growth.