NEONATAL UNILATERAL URETERAL OBSTRUCTlON:ROLE OF CASPASE-3 IN APOPTOSIS INDUCTlON

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

Merlo - San Luis - Argentina

Congreso; XXII Reunión Científica Anual de la Sociedad de Biología de Cuyo; 2004

Sociedad de Biología de Cuyo y Sociedad Argentina de Microscopía

Unilateral ureteral obstruction (UUO) is characterized by renal at­rophy and tissue loss, which is mediated by renal apoptosis. There exist two main apoptosis cascades, activated by extrinsic or intrin­sic stimuli. In the cell-external pathway, the intracellular signal transduction to the nucleus is carried out by caspases. We studied whether induced apoptosis in renal obstruction is mediated through the caspase cascade. Newborn female rats were subjected to complete left UUO (n = 8) within the first 48 hours of life.After 5 and 14 days of obstruction, their kidneys were removed. Apoptotic cells (AC) were identified with TUNEL. Quantification of AC was assessed by using an image analyzer. Hence a total area of 0.35 mm2 was counted. The numbers were expressed as AC per mm2± SEM. Caspase-3 protein expression was evaluated by Western blot­ting (WB) and inmunohistochemistry. WB analysis demonstrated that 32kDa procaspase-3 protein was increased two fold related to control after 5 days of obstruction. Downregulation of procaspase 3 protein due to its cleavage, 1.20 fold decrease, was observed af­ter 14 days of obstruction. Simultaneously, quantification of AC showed a significant increase of nearly five fold in cortical and medullary collecting ducts of obstructed kidney (OK) after 14 days compared to OK after 5 days. Our results suggest that by prolonging neonatal unilateral kidney obstruction, apoptosis is induced via a caspase dependent pathway.