SIRT3 SUMOylation confers AML chemoresistance via down-regulation of HES1 dependent fatty acid oxidation

SIRT3 deacetylase is a critical mitochondrial regulator for mitochondrial metabolism reprogramming and ROS production, and is involved in the regulation of chemoresistance in AML. SIRT3 is a SUMOylated protein, with de-SUMOylation by SENP1, resulted in enhancement of its deacetylase activity. However, the molecular mechanism of de-SUMOylation mediated SIRT3 activation, which may lead to reinforced AML chemoresistance, remains poorly understood. In the current study, we demonstrated that SIRT3 SUMOylation was attenuated by cytarabine, and de-SUMOylation prevented SIRT3 from proteasome degradation. SIRT3 de-SUMOylation was capable of reprogramming mitochondrial biogenesis, and subsequently inhibited mitochondrial ROS production. Furthermore, RNA-seq revealed that expression of a collection of genes was altered by SIRT3 de-SUMOylation, among which the transcription factor HES1, a downstream substrates of Notch1 signaling pathway, was significantly downregulated by SIRT3K288R, the de-SUMOylated and constitutively active mutant of SIRT3. HES1-dependent FAO was inhibited by SIRT3 de-SUMOylation. Moreover, cytarabine synergized with the SENP1 inhibitor momodrin-Ic to eradicate AML blasts in vitro and in xenografts mice models. In summary, the current study revealed a novel role of SIRT3 SUMOylation in regulating chemoresistance in AML via HES1-dependent FAO, which may provide a rationale for SIRT3 SUMOylation-targeted intervention to improve the chemotherapies in AML. Overall design: mRNA profiles of WT SIRT3 vs. VEC and SIRT3 K288R vs. WT SIRT3