Summary: The homeostatic balance of hepatic glucose uptake and production is exquisitely controlled by hormonal signals during feed-fast cycles. FoxO1, a transcription factor that functions in the regulation of glucose homeostasis, undergoes posttranslational modifications, such as acetylation, in response to hormonal signals, yet the mechanism remains poorly elucidated. Through expression profiling of 324 co-factors of CBP, a well-known acetyl-transferase of FoxO1, we identify Ets1 as a modulator of FoxO1 acetylation that is highly associated with feed-fast cycles. Mechanistic assays suggest that Ets1 enhances FoxO1 acetylation through the formation of a complex with CBP, which further promotes FoxO1 nuclear exclusion and inhibits its binding to gluconeogenic promoters. Functional studies further reveal that Ets1 inhibits gluconeogenesis under physiological and diabetes statuses, while the hyperinsulinemic-euglycemic clamp assay suggests hepatocyte Ets1 knockout mice have enhanced hepatic glucose production. Our study identifies Ets1 as an enhancer of FoxO1 acetylation and a repressor of hepatic gluconeogenesis in response to hormonal signals. : Dynamic control of FoxO1 activity, a transcription factor, is essential for maintaining glucose homeostasis during the fast-feed cycles. Li et al. show that Ets1 acts as a modulator of FoxO1 acetylation, through which it suppresses hepatic gluconeogenesis. Keywords: FoxO1, Ets1, CBP, acetylation, gluconeogenesis
