3T3-L1脂肪细胞诱导分化与肿瘤抑制因子PTEN的表达研究

目的 优化3T3-L1脂肪细胞分化条件,研究信号因子PTEN在分化过程中的表达,以了解PTEN是否通过表达量来调节正常脂肪细胞形成,为探索PTEN的药物靶标作用奠定基础.方法 DMEM高糖培养基培养3T3-L1脂肪前体细胞,地塞米松、3-异丁基1-甲基黄磦呤(IBMX)和胰岛素按2种组合方案分别诱导3T3-L1细胞分化,油红O染色鉴定脂肪细胞,蛋白裂解液提取细胞总蛋白,SDS-PAGE和Western blotting鉴定分化过程中PTEN的表达量,用生物信息学进行小鼠和人类PTEN的同源性分析.结果 1 μmol/L地塞米松、0.5 μmol/L mMX和5 μg/ml胰岛素诱导48 h后,再用含5 μg/ml胰岛素的DMEM高糖营养液培养48 h的方案对3T3-L1细胞诱导分化效果较好,脂肪细胞分化率高且均一,在分化第10天可见90%以上细胞分化为脂肪细胞.PTEN在脂肪细胞分化过程中表达量在第0、4 th、6 th、9 th和第12天时不一致,在12天时明显下降,显著低于诱导前.同源性比对分析表明,小鼠和人类的PTENmRNA编码序列匹配率为96%,而氨基酸序列匹配率为100%.结论 内源性PTEN在小鼠3T3-L1脂肪前体细胞诱导分化为脂肪细胞的时相过程中表达量有所变化,提示PTEN可能在生理条件下即可发挥提高胰岛素敏感性和促进脂肪细胞形成的作用.

Induced differentiation and signaling factor PTEN expression of 3T3-L1 adipocytes

OBJECTIVE: To optimize the condition for inducing the differentiation of 3T3-L1 preadipocytes into adipocytes and study the expression of PTEN tumor suppression gene in this process, aiming to understand the regulatory role of PTEN in normal adipocyte differentiation and collect laboratory evidence for developing drugs targeting PTEN. METHODS: The differentiation of 3T3-L1 preadipocytes cultured in high-glucose DMEM were induced according to 2 protocols with different combinations of dexamethasone, isobutylmethylxanthine (IBMX) and insulin, and the resultant adipocytes were identified by oil red O staining. The total proteins of 3T3-L1 were extracted and analyzed by Western blotting, and PTEN homology between mice and human was analyzed by bioinformatic method. RESULTS: For optimized 3T3-L1 differentiation, 3T3-L1 cells were initially induced with the combination of 1 micromol/L dexamethasone, 0.5 mmol/L IBMX and 5 microg/ml insulin for 48 h, followed by treatment with 5 microg/ml insulin in 4.5 g/L glucose DMEM for 48 h, which resulted in high differentiation rate of 3T3-L1 cells (up to 90% on the 10th day) with unified morphology and size. PTEN expression varied quantitatively in the process of differentiation, especially low on the 12th day as compared with those measured on days 4, 6 and 9. The mice PTEN mRNA shared 96% homology and PTEN amino acid 100% homology with their human counterparts. CONCLUSION: Endogenous PTEN expression is down-regulated during 3T3-L1 differentiation, suggesting that PTEN may enhance insulin sensitivity and promote adipogenesis under physiological conditions.