Effect of Phosphorylated Glucosamine on Adipocyte Differentiation in 3T3-L1 Preadipocytes

Abstract

Obesity is related directly or indiectly with several diseases such as diabetes, hypertension cancer, etc. For these reasons, obesity became one of the major social problems. Glucosamine was phosphorylated by phosphorous pentoxide (P2O5). Briefly N-phtalamide glucosamine was dissolved in methanesulfonic acid with adding phosphorous pentoxide (P2O5) followed by stirring at 5ºC for 4 h. In this study, effects of glucosamine-6-phosphate (Glc6-P) on adipocyte differentiation of 3T3-L1 cells were investigated by measuring triglyceride level and oil red o staining as indicators of lipid accumulation. In order to understand the mechanism by which lipid accumulation in adipocytes is decreased by phosphorylated glucosamine, the expression levels of several genes and proteins associated with adipogenesis and lipolysis were examined by using reverse transcription-polymerase chain reaction (PCR), real-time PCR and western blot analyses. Treatment with phosphorylated glucosamine significantly reduced lipid accumulation during adipocyte differentiation and induced down-regulation of PPARγ, SREBP1 and C/EBPα in a dose-dependent manner. Moreover, treatment with phosphorylated glucosamine during adipocyte differentiation induced significant up-regulation of Pref-1 mRNA as well as down-regulation of the adipocyte specific gene promoters such as aP2, FAS, LPL and leptin. As the lipolytic response, phosphorylated glucosamine up-regulated HSL mRNA expression and suppressed the expression levels of TNF mRNA compared to fully differentiated adipose tissue. These results suggest that inhibitory effect of phosphorylated glucosamine on adipocyte differentiation might be mediated through the down-regulation of adipogenic transcription factors such as PPARγ, SREBP1c and C/EBPα, related to the downstream of adipocyte specific gene promoters.