Ube2i, also known as the small ubiquitin-like modifier (SUMO) E2-conjugating enzyme, is crucial for SUMOylation, a post-translational modification process. SUMOylation is involved in various cellular processes such as regulating sub-cellular localization, the cell cycle, and gene expression [2,4].

In adipocytes, the generation of adipocyte-specific Ube2i knockout (Ube2ia-KO) mice revealed that Ube2i expression in mature adipocytes is necessary for white adipose tissue (WAT) expansion during postnatal growth. Deletion of Ube2i in fat cells leads to lipoatrophy, marked by local inflammation, loss of serum adipokines, hepatomegaly, and hepatic steatosis [1].

In cancer research, knockdown of Ube2i in cholangiocarcinoma cells inhibited cell proliferation, delayed xenograft tumor growth, and enhanced chemosensitivity, potentially due to p27kip1 nuclear accumulation [2]. In ovarian cancer, Ube2i depletion regulated tumor-associated macrophage polarization into M1 type through reprogramming glycolysis and increased the efficacy of anti-PD-L1 immunotherapy [3].

In conclusion, Ube2i is essential for normal adipocyte function and WAT expansion, with its deletion leading to lipoatrophy-related metabolic disorders. In cancer, Ube2i shows potential as a therapeutic target, as its knockdown can inhibit tumorigenesis and enhance chemosensitivity or immunotherapy efficacy in different cancer types. The use of Ube2i KO mouse models has been instrumental in uncovering these functions in both metabolic and cancer-related disease areas.