Dickkopf (Dkk)-2 is a beige fat-enriched adipokine to regulate adipogenesis

In the past decades, remarkable efforts have been made to unravel the regulation of adipose tissue metabolism, given the increasing prevalence of obesity and its huge impact on human health. Wnt signaling pathway is closely involved in this entity. As extracellular inhibitors to Wnt signaling, secreted protein Dickkopfs (Dkks) may be potential targets to combat obesity and related metabolic disorders. In this study, we showed that Dkk2 was a beige fat-enriched adipokine to regulate adipogenesis. Dkk2 was strikingly expressed in beige fat depot compared to classic white, brown, and subcutaneous fat. Dkk2 treatment inhibited adipogenesis in 3T3-L1 pre-adipocytes, C3H10T1/2 mesenchymal stem cells, and primary bone marrow mesenchymal stromal cells. Activation of the master adipogenic factor PPARγ by the synthetic Thiazolidinedione ligand rosiglitazone largely rescued the inhibition of adipogenesis by Dkk2. Furthermore, adenoviral overexpression of Dkk2 in the liver to mimic its gain-of-function showed minimal effect on whole-body metabolism. These results collectively suggest that Dkk2 is a first-in-class beige fat adipokine and functions mainly through a paracrine manner to inhibit adipogenesis rather than as an endocrine factor. Our findings aid a better understanding of beige fat function and regulation and further, provide a potential therapeutic target for treating obesity.