[Collectrin, a kidney-specific novel gene, is over-expressed in the hypertrophic phase in 5/6 nephrectomized rat...

To investigate the expression of the novel gene, collectrin, in the remnant kidney of the 5/6 nephrectomized rat.

Thirty-four rats were randomly assigned to three groups: sham-operation group (CON, n = 10), 5/6 nephrectomy group (NX, n = 12), NX + enalapril group (ACEI, since one day before the 5/6 nephrectomy 10 mg x kg(-1) x d(-1) enalapril was administered). Two weeks, 8 weeks, and 15 weeks after the above-mentioned treatments, 1/3 of the rats in different group were killed and their kidneys were taken out. Immunohistochemical staining was used to detect the expression of collectrin. The collectrin mRNA expression in the kidneys was detected by RT-PCR, and collectrin protein expression was observed by Western blot assay.

In the kidneys of the CON group rats, the expression of collectrin was progressively decreased over time (2 W vs 16 W, 1.69 +/- 0.09 vs 1.21 +/- 0.09, P < 0.05; 8 W vs 16 W, 1.38 +/- 0.04 vs 1.21 +/- 0.09, P < 0.05). However, collectrin was over-expressed in the remnant renal tissues compared with in the kidneys of control rats (NX vs CON, 2 W 2.33 +/- 0.07 vs 1.69 +/- 0.09, P < 0.05; 8 W 1.85 +/- 0.20 vs 1.38 +/- 0.04, P < 0.05; 16 W 1.47 +/- 0.17 vs 1.21 +/- 0.09, P < 0.05); In NX group, collectrin expression was obviously increased 2 weeks after the operation, then decreased along with the progression of renal failure (2 W vs 8 W, 2.33 +/- 0.07 vs 1.85 +/- 0.20, P < 0.05; 2W vs 16 W, 2.33 +/- 0.07 vs 1.47 +/- 0.17, P < 0.05; 8 W vs 16 W, 1.85 +/- 0.20 vs 1.47 +/- 0.17, P < 0.05). In ACEI treated group, collectrin expression was decreased along with the amelioration of renal lesions. The expression of collectrin mRNA was consistent with the expression of collectrin protein.

The expression of collectrin is progressively decreased with aging in normal rat kidney. In 5/6 nephrectomized kidney the expression of collectrin is related with the renal proliferation and hypertrophy.