Phosphorylated glucosamine inhibits adipogenesis in 3T3-L1 adipocytes

Phosphorylated glucosamine (glucosamine-6-phosphate, PGIc) was synthesized using methanesulfonic acid, phosphorus pentoxide (P2O5). NH2NH2 and DMF. Its inhibitory effect on lipid accumulation in cultured 3T3-L1 adipocytes was investigated by measuring triglyceride contents and Oil Red O staining. In order to understand the mechanism by which lipid accumulation in adipocytes is decreased by PGIc, we examined the expression levels of several genes and proteins associated with adipogenesis and lipolysis using reverse transcription polymerase chain reaction, real-time polymerase chain reaction and Western blot analysis. Treatment with PGIc significantly reduced lipid accumulation during adipocyte differentiation and induced down-regulation of peroxisome proliferator-activated receptor-gamma, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-alpha in a dose-dependent manner. Moreover, treatment with PGIc during adipocyte differentiation induced significant up-regulation of preadipocyte factor 1 mRNA and down-regulation of such adipocyte-specific gene promoters as adipocyte fatty acid binding protein, fatty acid synthase, lipoprotein lipase and leptin. According to the lipolytic response, PGIc up-regulated hormone-sensitive lipase mRNA expression and suppressed the expression levels of tumor necrosis factor-alpha mRNA compared with fully differentiated adipose tissue. These results suggest that the inhibitory effect of PGIc on adipocyte differentiation might be mediated through the down-regulation of adipogenic transcription factors, such as peroxisome proliferator-activated receptor-gamma, sterol regulatory element binding protein 1 and CCAAT/enhancer binding protein-alpha, which are related to the downstream adipocyte-specific gene promoters. (C) 2010 Elsevier Inc. All rights reserved.