Introduction & Objective: The ongoing obesity epidemic has raised awareness of the complex physiology of adipose tissue (AT). Abnormal adipocyte differentiation will result in the development of systemic metabolic disorders such as insulin resistance and diabetes. The conjugation of NEDD8 (neural precursor cell expressed, developmentally downregulated 8) to target protein, termed neddylation, has been shown to mediate adipogenesis by targeting PPARγ. However, much remains unknown about its role in adipogenesis.
Methods: Adipocyte differentiation was studied in 3T3-L1 cells and human Stromal vascular cells with pharmacological inhibition and genetic deletion by CRISPR/Cas9 of neddylation enzymes and its targeted cullins. Adipogenic signaling was analyzed by Western Blot, RT-PCR, FACS, etc.
Results: We first reported that neddylation and its targets, the cullin (CUL) family members, are differentially regulated during mouse and human adipogenesis. Neddylation inhibition by MLN4924 blunts adipogenesis in both 3T3-L1 cells and human stromal vascular cells. CRISPR/Cas9-mediated NAE1 deletion, a subunit of the only NEDD8 E1 enzyme, suppresses neddylation and impairs adipogenesis. Further studies identified that neddylation inhibition does not alter cell cycle progression, as evidenced by unaltered mitotic cell expansion. Instead, it impairs CREB-C/EBPβ-PPARγ signaling essential for adipogenesis. Furthermore, among different neddylation-targeted CULs, deletion of CUL3, but not CUL1, CUL2, and CUL4A, largely recapitulates neddylation deficiency-induced adipogenesis defects.
Conclusion: Our data establishes an indispensable role for neddylation and its target CUL3 in adipogenesis and suggests they can be important therapeutic targets for obesity.<u></u>
H. Zhou: None. W. Chen: None.
National Institutes of Health (1R56 DK135657 and 2R01HL132182)
