Phospholipase C-related catalytically inactive protein-knockout mice exhibit uncoupling protein 1 upregulation in adipose tissues following chronic cold exposure

Objectives: We have previously demonstrated that phospholipase C-related catalytically inactive protein (PRIP) is involved in fat metabolism and energy consumption. However, whether PRIP participates in body energy metabolism in vivo remains to be determined. Therefore, we examined whether PRIP deficiency affects whole-body energy homeostasis, which is modulated by non-shivering thermogenesis in brown adipose tissue, using a cold exposure animal model. Methods: Fasting plasma triacylglycerol levels were measured to evaluate fat metabolism in wild-type and Prip-KO mice. In addition, a glucose tolerance test (MT) and insulin tolerance test (ITT) were performed. To determine changes in energy consumption, mice were exposed to a cold environment for 7 days, and expression of uncoupling protein 1 (UCP1) in brown adipose tissue was analyzed via western blotting. Results: Fasting plasma levels of triacylglycerols were significantly higher in Prip-KO mice than in wild-type mice. However, Prip-KO mice showed a healthy phenotype based on OTT and ITT. UCP1 expression was significantly upregulated in the brown and white adipose tissues of Prip-KO mice exposed to cold conditions. Conclusion: Prip-KO mice exhibit greater ability to consume lipids as an energy source, indicating that PRIP modulates of systemic energy expenditure. Our findings provide increased understanding of PRIP-mediated non-shivering thermogenic mechanisms and offers important insights for the treatment and control of obesity. (C) 2017 Japanese Association for Oral Biology. Published by Elsevier B.V. All rights reserved.