SOX8-USP7-PGC-1α axis enhances thermogenesis in brown adipocytes
Obesity is one of the most prevalent diseases worldwide. Increasing thermogenesis to enhance energy expenditure has emerged as a promising therapeutic strategy. In an effort to identify new regulatory targets in thermogenic adipocytes, we found that SOX8 is correlated with obesity and serves as a novel marker of classical brown adipocytes in both humans and mice, upregulating during acute cold exposure. Functional studies further demonstrated that adipocyte-specific knockdown of SOX8 leads to obesity and metabolic dysfunction in mice. Mechanistically, SOX8 directly interacts with USP7 and stabilizes PGC-1 by reducing its K48-linked polyubiquitination. AAV-Rec2-mediated SOX8 overexpression initially enhanced energy expenditure, improved insulin sensitivity, and alleviated metabolic dysfunction in HFD-fed mice. However, prolonged SOX8 overexpression induced compensatory metabolic maladaptation, characterized by reduced energy expenditure, impaired glucose homeostasis, and mitochondrial structural disruption. These findings reveal a novel SOX8-USP7-PGC-1 regulatory axis in brown adipocytes, and reveal a previously unrecognized time-dependent effect of sustained thermogenic activation, highlighting SOX8 as a promising therapeutic target for obesity and metabolic syndrome.