INVESTIGADORES
PODEROSO Juan Jose
congresos y reuniones científicas
Título:
Mitochondrial nitric oxide modulates Sirt 3 activity delaying age-related mitochondrial damage
Autor/es:
PEREZ H, ALIPPE Y, CONVERSO DP, ELGUERO ME, PODEROSO JJ, CARRERAS MC
Lugar:
San Carlos de Bariloche, Rio Negro
Reunión:
Congreso; Second South American Spring Symposium in Signal Transductionnand Molecular Medicine; 2012
Resumen:
D. Harman proposed the oxidative stress theory of aging. We explored redox behavior of liver and brain mitochondria during aging in 3-24 mo. male/female rats. By Western blots and RT-PCR we observed increased nNOS transcription, translation and translocation with a significant progressive increment in mtNOS levels and NO production measured with DAF-FM by flow citometry. Wb against 3-nitrotyrosine antibody evidenced nitration of mitochondrial proteins at 18 mo. and 24 mo. and by imnunoprecipitation, we confirmed the nitration of Complex I, MnSOD and Sirt3. The progressive reduction in MnSOD activity (3 mo=1394±95 Vs 24 mo=921±11 nmoles/min.mg; p<0.05) contributed to a decrease in O2- scavenging favoring the formation of peroxynitrite (ONOO-). Complex I nitration was followed by a significant decrease of its activity (3 mo=341±48; 24 mo=203±19 nmoles/min.mg; p<0.05). In this condition, we analyzed the mitochondrial marker of aging sirtuin 3 (Sirt3), a deacetylase that participates in metabolic and cell cycle regulation. rSirt3 (recombinant Sirt3) activity exposed to liver and brain mitochondria lisates was higher at 18 mo (380±27 and 440±15 AU respectively; p<0.05) than at 3 mo (304±14 and 372±28 AU; p<0.05). Addition of 100 µM ONOO- to 3 mo brain mitochondria lisate significantly increased the rSirt3 activity (314±13 vs. 370±10 AU) while direct nitration of rSirt3 with 100-500 µM [ONOO-] significantly reduced its activity. Considering that ONOO- oxidizes NADH to NAD+, the substrate of Sirt3, we measured NAD+/NADH ratio and found an increase in 18 mo mitochondria in comparison to 3 mo organelles. We conclude that during aging, increased mitochondrial NO leads to protein