红细胞生成素3’端增强子在肺动脉平滑肌细胞低氧性增殖调控中的作用

Effect of erythropoietin 3’-enhancer on proliferation of pulmonary artery smooth muscle cells induced by hypoxia 

用噻唑蓝比色法 (MTT法 )、H3 胸腺嘧啶核苷 (H3 TdR)掺入法和流式细胞术 ,观察红细胞生成素 (EPO)3’端增强子片段对培养的猪肺动脉平滑肌细胞 (PASMCs)的内皮依赖性和非内皮依赖性低氧性增殖的影响。结果为 :(1)低氧 2 4h后PASMCs明显增殖 ,转入野生型EPO3’端增强子片段可被抑制 ,而转入突变型片段无此作用 ;(2 )肺动脉内皮细胞 (PAECs)低氧 2 4h ,其条件培养液有明显的促PASMCs增殖作用 ,将野生型EPO3’端增强子片段先转入PAECs,此作用明显减弱 ,而转入突变型片段则无明显影响。提示 :(1)PAECs低氧条件培养液可促进PASMCs增殖 ,PASMCs也可直接感受低氧而增殖 ,PAECs和PASMCs的低氧反应均被外源性EPO3’增强子片段抑制 ;(2 )由于EPO3’增强子上有低氧诱导因子 1(HIF 1)结合位点 ,PAEC和PASMC低氧反应可能是通过HIF

The effects of erythropoietin (EPO)3’ enhancer on endothelium dependent and endothelium indepen^dent proliferation caused by hypoxia in cultured porcine pulmonary artery smooth muscle cells (PASMCs) were investigated with MTT test, H 3 TdR incorporation and flow cytometry. The results showed that (1) PASMCs exposed to hypoxia for 24 h proliferated significantly, which was suppressed by pretransfecting wild type EPO3’ enhancer fragments into PASMCs, but not by protransfecting mutant fragments; and (2) the conditioned medium of pulmonary artery endothelial cells (PAECs) exposed to hypoxia for 24 h promoted the proliferation of PASMCs. This effect was abolished when wild type EPO3’ enhancer fragments were transfected, but it persisted when mutant fragments were transfected. The results suggest that (1) the conditioned medium of hypoxic PAECs induces proliferation of PASMCs. This may be because that not only PAECs are sensitive to hypoxia, but also PASMCs respond to hypoxia directly; and the hypoxic responses of both endothelial cells (ECs) and smooth muscle cells (SMCs) can be inhibited by exogenous EPO3’ enhancer fragments. (2) Since there is a HIF 1 binding site in EPO3’ enhancer, there may be a common pathway for HIF 1 hypoxia signal transduction in hypoxic responses of ECs and SMCs.