Glucose-sensitive acetylation of Seryl tRNA synthetase regulates lipid synthesis in breast cancer

Abnormally enhanced de novo lipid biosynthesis has been increasingly realized to play crucial roles in the initiation and progression of varieties of cancers including breast cancer. However, the mechanisms underlying the dysregulation of lipid biosynthesis in breast cancer remain largely unknown. Here, we reported that seryl tRNA synthetase (SerRS), a key enzyme for protein biosynthesis, could translocate into the nucleus in a glucose-dependent manner to suppress key genes involved in the de novo lipid biosynthesis. In normal mammary gland epithelial cells glucose can promote the nuclear translocation of SerRS by increasing the acetylation of SerRS at lysine 323. In SerRS knock-in mice bearing acetylation-defective lysine to arginine mutation, we observed increased body weight and adipose tissue mass. In breast cancer cells the acetylation and nuclear translocation of SerRS are greatly inhibited. Overexpression of SerRS, in particularly the acetylation-mimetic lysine to glutamine mutant, dramatically inhibits the de novo lipid synthesis and hence greatly suppresses the proliferation of breast cancer cells and the growth of breast cancer xenografts in mice. We further identified that HDAC4 and HDAC5 regulated the acetylation and nuclear translocation of SerRS. Thus, we identified a SerRS-meditated inhibitory pathway in glucose-induced lipid biosynthesis, which is dysregulated in breast cancer.