A p300 and SIRT1 Regulated Acetylation Switch of C/EBPα Controls Mitochondrial Function

Cellular metabolism is a tightly controlled process in which the cell adapts fluxes through metabolic pathways in response to changes in nutrient supply. Among the transcription factors that regulate gene expression and thereby cause changes in cellular metabolism is the basic leucine-zipper (bZIP) transcription factor CCAAT/enhancer-binding protein alpha (C/EBP alpha). Protein lysine acetylation is a key post-translational modification (PTM) that integrates cellular metabolic cues with other physiological processes. Here, we show that C/EBP alpha is acetylated by the lysine acetyl transferase (KAT) p300 and deacetylated by the lysine deacetylase (KDAC) sirtuin1 (SIRT1). SIRT1 is activated in times of energy demand by high levels of nicotinamide adenine dinucleotide (NAD(+)) and controls mitochondrial biogenesis and function. A hypoacetylated mutant of C/EBP alpha induces the transcription of mitochondrial genes and results in increased mitochondrial respiration. Our study identifies C/EBP alpha as a key mediator of SIRT1-controlled adaption of energy homeostasis to changes in nutrient supply.