Akt1 intramitochondrial cycling is a crucial step in the redox modulation of cell cycle progression.
Akt is a serine/threonine kinase involved in cell proliferation, apoptosis, and glucose metabolism. Akt is differentially activated by growth factors and oxidative stress by sequential phosphorylation of Ser(473) by mTORC2 and Thr(308) by PDK1. On these bases, we investigated the mechanistic connection of H(2)O(2) yield, mitochondrial activation of Akt1 and cell cycle progression in NIH/3T3 cell line with confocal microscopy, in vivo imaging, and directed mutagenesis. We demonstrate that modulation by H(2)O(2) entails the entrance of cytosolic P-Akt1 Ser(473) to mitochondria, where it is further phosphorylated at Thr(308) by constitutive PDK1. Phosphorylation of Thr(308) in mitochondria determines Akt1 passage to nuclei and triggers genomic post-translational mechanisms for cell proliferation. At high H(2)O(2), Akt1-PDK1 association is disrupted and P-Akt1 Ser(473) accumulates in mitochondria in detriment to nuclear translocation; accordingly, Akt1 T308A is retained in mitochondria. Low Akt1 activity increases cytochrome c release to cytosol leading to apoptosis. As assessed by mass spectra, differential H(2)O(2) effects on Akt1-PDK interaction depend on the selective oxidation of Cys(310) to sulfenic or cysteic acids. These results indicate that Akt1 intramitochondrial-cycling is central for redox modulation of cell fate.
Laboratory of Oxygen Metabolism, University Hospital, University of Buenos Aires, Buenos Aires, Argentina. vantico@hospitaldeclinicas.uba.ar
Valeria Gabriela
VG
Antico Arciuch
Soledad
S
Galli
María Clara
MC
Franco
Philip Y
PY
Lam
Enrique
E
Cadenas
María Cecilia
MC
Carreras
Juan José
JJ
Poderoso
D000818:Animals; D017209:Apoptosis; D002453:Cell Cycle; D019070:Cell Lineage; D003544:Cysteic Acid / Q000737:chemistry; D003600:Cytosol / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000737:chemistry; D051379:Mice; D008928:Mitochondria / Q000378:metabolism*; D008954:Models, Biological; D041681:NIH 3T3 Cells; D010084:Oxidation-Reduction; D010766:Phosphorylation; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D013434:Sulfenic Acids / Q000737:chemistry
D013434:Sulfenic Acids; D003544:Cysteic Acid; D006861:Hydrogen Peroxide; D051057:Proto-Oncogene Proteins c-akt