P300/CBP-associated factor regulates transcription and function of isocitrate dehydrogenase 2 during muscle differentiation

The epigenetic enzyme p300/CBP-associated factor (PCAF) belongs to the GCN5-related N-acetyltransferase (GNAT) family together with GCN5. Although its transcriptional and post-translational function is well characterized, little isknownabout its properties as regulator of cell metabolism.Here,we report the mitochondrial localization ofPCAF conferred by an 85 aamitochondrial targeting sequence (MTS) at the N-terminal region of the protein. Inmitochondria, one of the PCAF targets is the isocitrate dehydrogenase 2 (IDH2) acetylated at lysine 180. This PCAF-regulated posttranslational modification might reduce IDH2 affinity for isocitrate as a result of a conformational shift involving predictively the tyrosine at position 179. Site-directed mutagenesis and functional studies indicate that PCAF regulates IDH2, acting at dual level during myoblast differentiation: at a transcriptional level together with MyoD, and at a posttranslational level by direct modification of lysine acetylation inmitochondria. The latter event determines a decrease in IDH2functionwith negative consequencesonmuscle fiber formationinC2C12cells. Indeed,aMTS-deprivedPCAFdoes not localize into mitochondria, remains enriched into the nucleus, and contributes to a significant increase of musclespecific gene expression enhancing muscle differentiation. Therole of PCAFinmitochondria is a novel finding shedding light on metabolic processes relevant to early muscle precursor differentiation.-Savoia, M., Cencioni, C.,Mori, M., Atlante, S., Zaccagnini, G.,Devanna, P., Di Marcotullio, L., Botta, B., Martelli, F., Zeiher, A. M., Pontecorvi, A., Farsetti, A., Spallotta, F., Gaetano, C. P300/CBP-associated factor regulates transcription and function of isocitrate dehydrogenase 2 duringmuscle differentiation