CTNNB1/β-catenin dysfunction contributes to adiposity by regulating the cross-talk of mature adipocytes and preadipocytes

Overnutrition results in adiposity and chronic inflammation with expansion of white adipose tissue (WAT). However, genetic factors controlling fat mass and adiposity remain largely undetermined. We applied whole-exome sequencing in young obese subjects and identified rare gain-of-function mutations in CTNNB1/beta-catenin associated with increased obesity risk. Specific ablation of beta-catenin in mature adipocytes attenuated high-fat diet-induced obesity and reduced sWAT mass expansion with less proliferated Pdgfr alpha(+) preadipocytes and less mature adipocytes. Mechanistically, beta-catenin regulated the transcription of serum amyloid A3 (Saa3), an adipocyte-derived chemokine, through beta-catenin-TCF (T-Cell-Specific Transcription Factor) complex in mature adipocytes, and Saa3 activated macrophages to secrete several factors, including Pdgf-aa, which further promoted the proliferation of preadipocytes, suggesting that beta-catenin/Saa3/macrophages may mediate mature adipocyte-preadipocyte cross-talk and fat expansion in sWAT. The identification of beta-catenin as a key regulator in fat expansion and human adiposity provides the basis for developing drugs targeting Wnt/beta-catenin pathway to combat obesity.