Adipose-specific HuR deletion protects against high-fat diet-induced obesity in mice through upregulating Ucp1 expression.

Background: RNA-binding proteins (RBPs) have been proved to play essential roles in post-transcriptional regulation of genes associated with adipogenesis. However, the role of the RBP human antigen R (HuR) in the pathogenesis of obesity remains to be clarified.

Methods: Adipocyte-specific HuR knockout (HuR^-/-) and HuR floxed (HuR^f/f) mice were fed a high-fat diet (HFD), or a paired normal control diet (NC) for 16 weeks. Moreover, 8-week-old HuR^-/- or HuR^f/f mice were subjected to cold exposure or CL316,243 treatments. The mouse body weight was recorded and the histological changes in adipose tissue were examined. RNA sequencing analysis and RT-qPCR were used to identify potential target genes for HuR. The regulation of HuR on the uncoupling protein 1 (Ucp1) expression was determined using RNA immunoprecipitation (RIP), RNA pull-down, and Luciferase assays.

Results: Adipocyte-specific HuR deletion inhibited body weight gain with HFD feeding, being accompanied by less BAT whitening and more WAT browning, and up-regulated expressions of adipose thermogenic genes (Pgc-1α, Ucp1, etc.). HuR could bind to the 3'UTR of the Ucp1 mRNA, and thus downregulated its expression. In addition, although the HuR expression was not changed in obesity, there was an enhanced transfer of HuR protein from the nuclear to cytoplasm, thus impacting the expression of target genes including the Ucp1.

Conclusions: These findings indicate that adipose tissue-specific HuR deletion alleviates HFD-induced obesity by promoting adipose thermogenesis through upregulating Ucp1 expression.