233-LB: Role of SUMO-Specific Protease 2 (SENP2) in Modulating Brown Adipose Tissue Activity

Brown adipose tissue (BAT) is a metabolically active endocrine organ. Activation of BAT contributes to increased energy expenditure through systemic glucose and lipid utilization. SUMO-specific protease 2 (SENP2) is a post-translational protein modifier that is involved in regulation of metabolism in different tissues. We had previously showed that while SENP2 suppresses browning of white adipose tissues, morphologic defect in BAT was observed in adipose specific SENP2 deficient mice fed with high fat diet. How SENP2 may modulate BAT activity has not been elucidated yet. BAT-specific Senp2 knockout (Senp2-BKO, Ucp1-Cre;Senp2f/f) mice were more insulin resistant in response to high fat diet than controls. They were also intolerant to acute cold exposure. Mechanistically, knockdown of Senp2 in brown adipocytes resulted in reduced levels of Ucp1 and Cidea through SUMOylation of ERRα. SUMOylation of ERRα interrupted binding of ERRα to ERRα response element (ERRE) in the Ucp1 promoter, and deSUMOylation of ERRα via SENP2 enhanced the synergistic effect of ERRα/PGC-1α complex required for the transcription of Ucp1. Collectively, these results suggest that SENP2 is intimately involved in modulating the activity of Ucp1 in BAT through deSUMOylation of ERRα/PGC-1α complex, especially ERRα.