HIF-1α介导低氧诱导的内皮细胞Brm表达上调的机制研究

目的:本研究拟探讨低氧诱导因子1α(HIF-1α)在低氧诱导的血管内皮细胞Brm表达上调中的作用及机制,为低氧性肺动脉高压的防治提供理论依据。方法:在内皮细胞中过表达或siRNA干扰HIF-1α的表达,并给予1%低氧处理24 h后,运用萤光素酶报告基因检测方法检测Brm启动子的转录活性,运用RT-qPCR检测Brm的mRNA表达水平,运用Western blot检测Brm的蛋白表达水平。运用ChIP技术检测低氧条件下HIF-1α与Brm启动子区域的结合变化情况。结果:过表达HIF-1α可显著上调Brm的启动子活性、mRNA及蛋白表达,而siRNA干扰HIF-1α可显著抑制Brm的启动子活性、mRNA及蛋白表达,ChIP实验揭示低氧可显著增强HIF-1α与Brm启动子的结合。结论:低氧上调内皮细胞中Brm的表达依赖HIF-1α的转录调控作用。

HIF-1α mediates hypoxia-induced Brm transactivation in endothelial cells

AIM: To clarify the molecular mechanism of Brm activation in endothelial cells during hypoxia and hypoxic pulmonary hypertension. METHODS: Hypoxia-inducible factor 1 alpha (HIF-1α) was over-expressed or depleted in the endothelial cells under hypoxia. Luciferase activity was assayed after transfection using a luciferase reporter assay system. The expression of Brm at mRNA and protein levels was detected by RT-qPCR and Western blot. The occupancy of HIF-1α on Brm promoter was detected by the method of chromatin immunoprecipitation (ChIP). RESULTS: Brm expression was induced in cultured endothelial cells challenged with hypoxia. Over-expression of HIF-1α enhanced, while the depletion of HIF-1α attenuated Brm transactivation and expression under hypoxia. The results of ChIP revealed that hypoxia up-regulated the occupancy of HIF-1α on Brm promoter. CONCLUSION: HIF-1α, which is induced by hypoxia, binds to Brmpromoter, and further promotes Brm transactivation in endothelial cells.