SIRT2 mediates integrated stress response by deacetylating and stabilizing 4E-BP1 to suppress translation

The ability to adapt to nutrient stress, such as amino acid limitation, is crucial for cell survival. The mTORC1 complex and integrated stress response (ISR) are two mechanisms that sense the availability of amino acids and regulate protein synthesis. Here, we reveal a new SIRT2-mediated pathway, downstream of the ISR, that is activated under amino acids limitation to suppress global translation. Under amino acid deprivation, SIRT2 protein level is upregulated translationally by its upstream open reading frame (uORF). SIRT2 in turn suppresses translation, which helps cells to survive amino acid limitation. We identify eukaryotic translation initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), which binds to eIF4E and inhibits translation, as a substrate of SIRT2. SIRT2 deacetylates 4E-BP1 at lysine 69 and stabilizes 4E-BP1 by protecting it from proteasomal degradation, leading to suppression of global translation. Our study uncovers a role for SIRT2 in regulating translation and identifies a new regulatory mechanism of 4E-BP1 in cells.