甘露糖-6-磷酸对脂肪细胞分化的影响及其分子机制初探

目的 探讨甘露糖-6-磷酸(M6P)对脂肪细胞分化的影响及其分子机制.方法 油红O染色、测定TG及甘油含量观察M6P对3T3-L1前脂肪细胞株脂肪细胞分化进程的影响.激光共聚焦显微镜下观察组织蛋白酶K(CTSK)酶活性变化,四甲基偶氮唑盐比色法(MTT)检测前脂肪细胞增殖情况,同时RT-PCR检测M6P受体(M6PR)转录表达.结果 经不同浓度M6P干预后,油红O染色逐渐变浅,当M6P 10 mmol/L时细胞完全不被染色.同时TG合成及甘油含量明显下降,有剂量依赖关系,浓度分别为5 mmol/L和8 mmol/L时即与对照组差异有统计学意义(P＜0.05).脂肪细胞分化进程中的不同时间点均可检测到M6PR mRNA表达.加入M6P后CTSK酶活性呈剂量依赖性被抑制,10 mmol/L时,CTSK酶活性被完全抑制.MTT显示M6P加入后细胞增殖,10 mmol/L的M6PA值达到0.057±0.091,与对照组相比增加了62.9%(P＜0.05).结论 在3T3-L1前脂肪细胞中同样有M6PR表达,M6P可能通过竞争结合M6PR抑制CTSK酶活性,从而影响脂肪细胞分化进程.

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

Objective 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. Methods Oil red O staining, accumulation of cytoplasmic triglycerides and glycerine release were used to assess its effects on adipocyte differentiation in the 3T3-L1cell 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 RTPCR. Results 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 M6Pconcentration, 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 ). Conclusion M6P inhibits the terminal differentiation of adipocyte, which may be associated with its effect of blocking CTSK activity by competitive binding with M6PR.