mTOR信号调控PPARγ对再生障碍性贫血BM-MSC成脂分化的作用

Effect of Regulating PPARy by mTOR Signaling on Adipogenesis of Bone Marrow Mesenchymal Stem Cells from Aplastic Anemia

目的:研究哺乳动物雷帕霉素靶蛋白(m TOR)信号通过调控过氧化物酶体增殖物激活受体γ(PPARγ)表达对再生障碍性贫血(AA)患者骨髓间充质干细胞(BM-MSC)成脂分化的影响。方法:采用激光共聚焦、Western blot和油红O染色等,观察AA组和对照组BM-M SC中m TOR信号、PPARγ蛋白表达和体外诱导成脂分化能力;通过雷帕霉素体外干预,分析m TOR信号和PPARγ在AA患者BM-MSC体外诱导成脂分化中的作用。结果:随着成脂诱导时间的延长,2组脂肪细胞转化率和FABP4表达均增高,在同一时间点,在AA组均高于对照组(P<0.01)。2组BM-M SC的胞质及胞核均有p-m TOR和PPARγ的分布,而且AA组p-m TOR和PPARγ蛋白的荧光强度均显著高于对照组(P<0.01)。随诱导时间的延长,2组PPARγ表达均呈逐渐增高的趋势;在同一时间点,AA组PPARγ表达明显高于对照组(P<0.01)。雷帕霉素早、中和晚期干预组脂肪转化率和FABP4表达均较未干预组明显下降(P<0.001)。雷帕霉素早、中和晚期干预组的PPARγ蛋白和m RNA表达均较未干预组均明显下降(P<0.001)。结论:m TOR信号可能通过调控PPARγ表达在AA患者BM-MSC体外成脂分化中发挥重要的作用。

Objective： To study the effect and mechanism of mTOR signaling on adipogenesis of bone marrow mesenchymal stem cells （ BM - MSCs） from aplastic anemia （AA） patients through regulation of PPAR~/. Methods： BM - MSCs were isolated from 24 newly diagnosed AA patients and 24 healthy controls. The surface antigen expression of BM - MSCs was identified by flow cytometry. The capacity of adipogenic differentiation of BM - MSCs was determined by lipid droplets based on Oil Red O staining and by the expression of FABP4 based on Western blot. Protein levels of mTOR signaling and PPARγ were tested by immunofluorescence and Western blot. Results： AA BM - MSCs displayed an enhanced capacity of differentiating into adipocytes, compared with control BM - MSCs. It was found that mTOR was activated in AA BM - MSCs. Moreover, the expression levels of p-mTOR and PPAR-~/in AA BM - MSCs showed a parallel differentiation-dependent increase during adipogenic differentiation, which were significantly higher than that of control BM - MSCs at the same time point of adipogenic differentiation, roTOR inhibitor rapamycin did not only inhibit the adipogenic differentiation of BM - MSCs from AA pateints at the early-middle stage, but also partly reversed the adipogenic differention of BM - MSCs from AA pateints at the late stage by PPARγ regulation. Conclusion： mTOR signaling may play a critical role in the adipogenic differentiation of BM - MSCs from AA patients by positively regulating PPARγ expression.