The effect of mannose-6-phosphate on adipocyte differentiation and its underlying molecular mechanism]

Cathepsin K (CTSK) played an important role in adipocyte differentiation. The activation of CTSK needs to convey by mannose-6-phosphate receptors (M6PR) in osteoclasts. The aim of the present study was to identify the effects of mannose-6-phosphate (M6P) in adipocyte differentiation and its underlying molecular mechanism.Oil red O staining, accumulation of cytoplasmic triglycerides and glycerine release were used to assess its effects on adipocyte differentiation in the 3T3-L1 cell line. The enzyme activity of CTSK was observed by laser confocal microscopy. The proliferation of 3T3-L1 preadipocytes was detected by MTT methods. mRNA expression of M6PR was determined by RT-PCR.M6P could prevent adipocyte differentiation in a dose-dependent manner as evidenced by absence of triglyceride accumulation and glycerol content. Statistical significance was showed when the concentrations of M6P were 5.0 mmol/L and 8.0 mmol/L respectively (P < 0.05). The mRNA expression of M6PR was detected during the whole process of adipocyte differentiation. With the increase of M6P concentration, enzyme activity of CTSK was inhibited in a concentration-dependent manner. MTT method showed that the absorbance at 570 nm of 3T3-L1 preadipocytes was 0.057 ± 0.091, increased about 62.9% at 10.0 mmol/L compared with the control group (P < 0.05).M6P inhibits the terminal differentiation of adipocyte, which may be associated with its effect of blocking CTSK activity by competitive binding with M6PR.