INVESTIGADORES
PODEROSO Juan Jose
congresos y reuniones científicas
Título:
Cell cycle progression depends on redox modulation of Akt1 activation in mitochondria
Autor/es:
ANTICO ARCIUCH VG, GALLI S, FRANCO MC, CARRERAS MC, PODEROSO JJ
Lugar:
Roma, Italia
Reunión:
Congreso; SFRR-Europe Meeting 2009. Free Radicals, Health and Lifestyle: from Cell Signalling to Disease Prevention.; 2009
Institución organizadora:
SFRR-Europe
Resumen:
Akt is a ser/thr kinase, which regulates cellular responses and becomes differentially activated by growth factors, cytokines and oxidative stress. For complete activation, it requires to be sequentially phosphorylated in Ser473 by mTOR2C and in Thr308 by PDK1. Previously, we demonstrated that H2O2 induces Akt1 subcellular redistribution which correlates with a differential cell response. Low H2O2 causes rapid translocation to nucleus with a proliferative phenotype while high H2O2 promotes retention in mitochondria associated with apoptosis. The aim of this work was to study mitochondrial contribution to Akt1 activation under redox stimuli in the NIH/3T3 cell line. Subcellular distribution of Akt1 was followed by transfection with Akt1 Wt or T308A and analyzed by western blot. In vitro phosphorylation assay was carried out using inactive Akt1 and mTORC2. Translocation to mitochondria was then evaluated incubating the extracts with purified organelles in import buffer and total and P-Akt was assessed by western blot. PDK1-Akt1 binding was evaluated by a pull down assay. We demonstrate that a) Akt1 requires Ser473 phosphorylation to enter into mitochondria, where it is further phosphorylated at Thr308 by mtPDK1; b) low H2O2 favors while high H2O2 impedes Akt1-PDK1 interaction in the organelles; c) Akt1 activity increases at low H2O2 while decreases at high H2O2 due to incomplete activation, d) Akt1 T308A is retained in mitochondria and cannot reach the nucleus. We conclude that mitochondria are central partners of Akt1 signaling and that, depending on redox status, they regulate Akt1 phosphorylation at Thr308 and contribute to drive cell fate to proliferation or apoptosis.