Early response of antioxidant enzymes to Tl(I)- and Tl(III)-mediated oxidative stress in PC12 cells

PUGA MOLINA LC; VERSTRAETEN SV

Cordoba

Congreso; LII Reunión Anual Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.; 2016

Sociedad Argentina de Investigación en Bioquímica y Biología Molecular.

Thallium is a toxic metalthat causes oxidative stress in PC12 cells. In this work we evaluated oxygen(ROS)- and nitrogen (RNS)-reactive species production after 6 h of cellexposure to Tl(I) or Tl(III), and how main antioxidant enzymes respond toeliminate them. Both cations increased ROS and RNS contents, returning tobaseline values after 6 h of incubation. H2O2 generation via superoxidedismutase (CuZnSOD and MnSOD) was impaired by Tl as well as its degradation bycatalase. Glutathione-dependent system was also affected by Tl: whileglutathione peroxidase (GPx) expression and activity were increased by Tl(III),glutathione reductase (GR) expression was decreased by both cations. However,GR activity was mildly enhanced by Tl(III). Finally, thioredoxin-dependentsystem was evaluated. Peroxyredoxin expression was increased by Tl(I) althoughits activity was increased by both cations. Cytosolic thioredoxin reductase(TrxR1) expression was increased by Tl(I) and partially decreased by Tl(III),while the mitochondrial isoform (TrxR2) was not affected. However, total TrxRactivity was increased by both cations. Obtained results suggest thatglutathione- and thioredoxin-dependent antioxidant defense systems areresponsible for ROS and RNS detoxification generated upon PC12 cell exposure toTl(I) or Tl(III). Worksupported by the University of Buenos Aires and ANPCyT, Argentina.