APOPTOSIS INDUCTION IS ASSOCIATED WITH DECREASED NHE1 EXPRESSION IN NEONATAL UNILATERAL URETERAL OBSTRUCTION (UUO)

WALTER MANUCHA; LILIANA CARRIZO; CELESTE RUETE; PATRICIA G. VALLES

BJU INTERNATIONAL.

Blackwell Science

Lugar: England; Año: 2007 vol. 100 p. 191 - 198

1464-4096

The ubiquitously expressed NHE1 isoform is an important regulatory volume increase component (RVI). Objetive: We examined the NHE1 participation in the regulation of the apoptotic response in neonatal obstruction. Materials and Methods: Rats were subjected to UUO or sham operation, and kidneys were harvested 5 and 14 days after obstruction. Cellular apoptosis in proximal tubules (PT) and collecting ducts (CD) by TUNEL assay and NHE1 expression by RT-PCR and Western Blot from renal cortex, were determined. Mitochondrial apoptosis was evaluated by Bax/BcL2 expression and caspase 3 expression and activity. In addition, in vivo administration of increased EIPA doses on NHE1 inhibition associated to apoptosis induction, were evaluated. Results: After 14 days, a consistently greater number of apoptotic cells in CD than in PT, associated with decreased expression of NHE1 at the mRNA and protein levels, were shown. Increased expression of Bax/BcL2 ratio was demonstrated, linked to decreased pro-caspase 3 protein levels with increased caspase 3 activation. NHE1 inhibition by increased doses of EIPA, induced epithelial cell apoptosis and increased caspase 3 activity in dose-dependent manner. After in vitro incubation with amiloride (100mM), deacreased NHE1 expression was demonstrated to be associated to reduced 32 kDa procaspase 3 protein levels. Kidneys obstructed for 5 days showed neither changes in NHE1 expression nor apoptosis induction. Conclusion: For these results we suggest that the decreased NHE1 expression could be a signal transduction event that participates in epithelial tubular cell apoptosis induction through the regulation of the BcL2 gene family and activation of caspase 3 in neonatal obstruction.