INVESTIGADORES
PODEROSO Juan Jose
congresos y reuniones científicas
Título:
Effects of iNOS translocation to mitochondria in experimental endotoxemia
Autor/es:
CARRERAS MC; FRANCO MC; ANTICO ARCIUCH V; PODEROSO JJ
Lugar:
St Thomas, EEUU
Reunión:
Congreso; 11th Annual Meeting of the Society for Free Radical Biology and Medicine; 2004
Institución organizadora:
Society for Free Radical Biology and Medicine
Resumen:
Experimental endotoxemia  is accompanied by organ failure and mitochondrial dysfunction characterized by uncoupling of oxidative phosphorylation, increased production of oxygen active species and nitrosative stress attributed to high NO yield resulting from cytokine-dependent iNOS induction. The objective of this study was to analyze iNOS traffic to mitochondria in endotoxemia and its effects on cell metabolism. Wistar rats were inoculated i.p with 10 mg E.coli LPS, and mitochondria from excised liver were obtained from 2 to 24 h. iNOS mRNA and protein peaked at 2 h and were maximal at 4-6 h; 2 h later iNOS was detected in mitochondria and was confirmed by western blot and immunoelectron microscopy. At 6 h, submitochondrial fractionation showed maximal iNOS content in the intermembrane space that decreased at outer and inner membrane while mtNOS was enriched in inner membrane. iNOS disappeared from the mitochondrial compartment at 12-24 h; in the same period, mitochondrial HO-1 increased by ten-fold. Protein nitration and selective decrease of Complex I activity were detected at 6-12 h in parallel to maximal activation of Akt, which may regulate mitochondrial biogenesis. The results suggest that a) traffic to mitochondria follows increased iNOS expression b), mitochondrial damage is mainly due to translocated iNOS c) tyrosine nitration and impaired function are restored by  protein denitration or mitochondrial biogenesis, just after iNOS is degraded by specific catabolic enzymes also translocated to mitochondria, like HO-1.