S100A4 protects mice from high-fat diet-induced obesity and inflammation.

As a member from S100 calcium-binding protein family, S100A4 is ubiquitous and elevated in tumor progression and metastasis, but its role in regulating obesity has not been well characterized. In this study, we showed that S100A4 was mainly expressed by stromal cells in adipose tissue and the S100A4 level in adipose tissue was decreased after high-fat diet (HFD). S100A4 deficient mice exhibited aggravated symptoms of obesity and suppressed insulin signaling after 12 weeks of HFD. Aggravated obesity in S100A4 deficient mice were found to be positively correlated with higher inflammatory status of the liver. Then, we found that extracellular S100A4 or overexpressed S100A4 inhibited adipogenesis and decreased mRNA levels of inflammation gene in 3T3-L1 adipocytes in vitro; whereas small interfering RNA (siRNA)-mediated suppression of S100A4 displayed the opposite results. Additionally, the protective effect induced by S100A4 during HFD-induced obesity was tightly related with activation of Akt signaling in adipose tissues, as well as livers and muscles. Taken together, we demonstrate that S100A4 is an inhibitory factor for obesity and attenuates the inflammatory reaction, while activating the Akt signaling, which suggest that S100A4 is a potential candidate for the treatment of diet-induced obesity and its complications.