WDR4-mediate tRNA m7G modification to promote mitophagy and browning of white adipose tissue for ameliorating obesity in male mice

Objective: Brown adipose tissue activation is a potential anti-obesity strategy. N⁷-methylguanosine (m⁷G) modification is a novel RNA epigenetic modification, but its role in adipose metabolism remains unexplored.

Methods: Male mice were fed a high-fat diet (HFD), followed by PCR array screening. Gain-of-function experiments and TRAC-seq were employed to explore WDR4 function.

Result: A Mouse Epigenetic Modification Enzymes PCR Array revealed that WDR4 expression showed the most pronounced downregulation in HFD mice. Overexpression of WDR4 in 3T3-L1 cells and primary adipocytes significantly increased UCP1 expression and suppressed lipid droplet formation, and enhanced Mitophagy as evidenced by mitochondrial ultrastructure, autophagic vesicles, and LC3 expression. Suppression of Mitophagy using 3-MA and bafilomycin A1 attenuated WDR4-induced adipocyte browning. WDR4 overexpression enhanced translational activity and reshaped the tRNA m⁷G methylome in 3T3-L1 adipocytes, specifically induced 38 unique tRNA m⁷G modification sites, and increasing cleavage scores of multiple tRNAs. GSE229240 dataset revealed that WDR4 mutation significantly reduced translation efficiency of 195 genes enriched in the TGF-β signalling , including BMP8B. Knockdown of BMP8B partially counteracted WDR4-mediated Mitophagy.

Conclusion: WDR4 promotes adipocyte browning by enhancing BMP8B translation through tRNA m⁷G modification, revealing a novel m⁷G epitranscriptomic mechanism with therapeutic potential for obesity.

Obesity; WDR4; brown adipose tissue; mitophagy; tRNA m7G modification.