GADD45β基因在脂肪细胞分化过程中的表达及肿瘤坏死因子-α对其的调节作用

Expression of Growth Arrest and DNA Damage Inducible Gene 45 β during Preadipocyte Differentiation and Regulative Role of Tumor Necrosis Factor-Alpha

目的观察3T3-L1脂肪细胞诱导分化过程中生长抑制和DNA损伤诱导家族45β（GADD45β）基因mRNA表达水平的变化，探讨TNF—α对成熟脂肪细胞中GADD45β基因表达水平的调节作用。方法体外培养3T3-L1脂肪细胞，在诱导3T3-L1脂肪细胞分化成熟的基础上，应用重组TNF—α干预分化成熟的脂肪细胞，采用逆转录-聚合酶链反应（RT-PCR）技术检测诱导分化不同时段及TNF-α干预后不同时间脂肪细胞中GADD45β基因表达水平。结果随脂肪细胞逐渐分化成熟，GADD45β基因mRNA表达水平渐降低。GADD45β基因表达水平除在细胞分化d1～7、d8～10各时段内差异无显著意义（P〉0．05）外，余各时段之间表达水平差异均具有最著意义（P〈0.05）。不同质量浓度重组TNF-α（0．1～10．0μg/L）均能显著促进成熟脂肪细胞中GADD45β基因mRNA的表达。TNF-α质量浓度为0.1μg／L时，GADD45β基因表达水平6h内上升51．39％，24h内上升100．15％；TNF—α质量浓度为1．0μg／L时，GADD45β基因表达水平6h内上升44．15％，24h内上升100．63％；TNF—α质量浓度达10．0μg/L，GADD45β基因表达水平6h内即上升104．26％，24h内上升122．17％。结论GADD45β基因可能参与脂肪细胞分化及脂质形成过程；TNF-α对成熟脂肪细胞中GADD45β基因表达具有促进作用，其促进效应总体趋势呈现时间依赖性特征。

Objective To investigate the changes of growth arrest and DNA damage inducible gene β（GADD45β）expression during 3T3 - L1 preadipocyte differentiation and analyze the regulative role of tumor necrosis factor - alpha（TNF - α） on GADD45β gene expression in matured 3T3 - L1 adipocytes. Methods 3T3 - L1 preadipocytes were cultured in vitro and differentiated into the matured adipocytes. TNF-α in different concentrations（0.1,1.0,10.0μg/L） was added into the culture medium of fully differentiated adipocytes （day 10） for various times（0.5,2,6,12,24 h）. The levels of GADD45β gene mRNA expression were evaluated by reverse transcription polymerase chain reaction（RT- PCR）. Results With the 3T3 - L1 preadipocytes being differentiated into the matured adipocytes, the level of GADD45β gene mRNA expression was downregulated and reached the lower level in fully differentiated adipocytes. There was a significant difference between any 2 detected phases in the levels of GADD45β gene mRNA expression（ P〈 0.05 ）, except that the levels of GADD45β gene mRNA expression did not decrease obviously on day 1 to day 7, day 8 to day 10 （ P 〉 0.05 ）. Treatment of day 10 3T3 - L1 adipocytes with TNF - α of different concentrations resulted in a significant increase in the level of GADD45β gene mRNA expression. The induction effect of TNF- α on GADD45β gene mRNA expression generally tended to be reinforced with the elongation of time course. Conclusions GADD45β gene may be involved in adipocyte differentiation and adipogenesis. TNF- α can upregulate the mRNA expression of GADD45β gene in matured adipocytes. The induction effect of TNF-α on GADD45β gene expression is generally time- correlated.