Oxidative stress promotes SIRT1 recruitment to the GADD34/PP1? complex to activate its deacetylase function.

ABSTRACT: Phosphorylation of the eukaryotic translation initiation factor, eIF2?, by stress-activated protein kinases and dephosphorylation by the growth arrest and DNA damage-inducible protein (GADD34)-containing phosphatase is a central node in the integrated stress response. Mass spectrometry demonstrated GADD34 acetylation at multiple lysines. Substituting K315 and K322 with alanines or glutamines did not impair GADD34's ability to recruit protein phosphatase 1? (PP1?) or eIF2?, suggesting that GADD34 acetylation did not modulate eIF2? phosphatase activity. Arsenite (Ars)-induced oxidative stress increased cellular GADD34 levels and enhanced Sirtuin 1 (SIRT1) recruitment to assemble a cytoplasmic complex containing GADD34, PP1?, eIF2? and SIRT1. Induction of GADD34 in WT MEFs paralleled the dephosphorylation of eIF2? (phosphoserine-51) and SIRT1 (phosphoserine-47). By comparison, eIF2? and SIRT1 were persistently phosphorylated in Ars-treated GADD34-/- MEFs. Expressing WT GADD34, but not a mutant unable to bind PP1? in GADD34-/- MEFs restored both eIF2? and SIRT1 dephosphorylation. SIRT1 dephosphorylation increased its deacetylase activity, measured in vitro and in cells. Loss of function of GADD34 or SIRT1 enhanced cellular p-eIF2? levels and attenuated cell death following Ars exposure. These results highlighted a novel role for the GADD34/PP1? complex in coordinating the dephosphorylation and reactivation of eIF2? and SIRT1 to determine cell fate following oxidative stress.

SUBMITTER: Lee IC 

PROVIDER: S-EPMC5762841 | biostudies-other | 2018 Feb

REPOSITORIES: biostudies-other