Sphingosine Kinase 2 Knockout Mice Resist HFD-Induced Obesity Through Increasing Energy Expenditure

BACKGROUND: It has been reported that sphingosine kinase (SK) 2 plays a role in maintaining metabolism and glucose homeostasis. However, the mechanism remains uncertain. OBJECTIVES: The present research aimed to further investigate the effect of SK2 knockout on high-fat diet (HFD)-induced obesity and metabolic regulation. METHODS: Male SK2−/− and wild-type (WT) control mice were challenged with HFD for 8 weeks. Then, body composition, inguinal white adipose tissue (IWAT) histology, intraperitoneal glucose tolerance tests (IPGTT), and metabolic parameters were examined, and expression levels of uncoupling protein 1 (UCP1), a key molecular marker of thermogenesis, in IWAT were determined. RESULTS: After 8 weeks of HFD challenge, compared with WT mice, SK2−/− mice displayed decreased whole body, epididymal white adipose tissue (EWAT) and IWAT weights, reduced fat/lean body mass ratios and inguinal adipocytes size; also, SK2-/- mice exhibited improved intraperitoneal glucose tolerance. Next, elevated energy expenditure was observed in SK2−/− mice compared with WT mice; however, neither food intake nor physical activity showed obvious difference between SK2-/- and WT mice. Furthermore, we found that the expressions of UCP1 was markedly increased in IWAT from SK2-/- mice. CONCLUSIONS: SK2-/- mice may resist HFD-induced obesity through increasing energy expenditure by promoting thermogenesis in the beige adipose tissue.