缺氧、复氧条件下低氧反应元件（HRE）对心肌细胞转染hVEGF165基因表达的调控作用

目的：探讨缺氧、复氧条件下，低氧反应元件(HRE)作为氧条件基因表达控制开关，对心肌细胞转染rAAV-HRE9-hVEGF165基因表达的调控作用。方法:分离新生SD大鼠心肌细胞,采用无血清培养,将在HEK293T细胞进行包装后获得的腺相关病毒转染培养的心肌细胞。实验共分为8组：Ⅰ组（空白对照组）：常氧培养 24 h（氧浓度21％）；Ⅱ组（缺氧对照组）：常氧培养16 h，缺氧8 h（氧浓度1％）；Ⅲ组（转基因对照组）：常氧培养 24 h；Ⅳ组（转基因缺氧1组）：转基因后缺氧8 h；Ⅴ组（复氧1组）：常氧培养16 h，缺氧8 h、复氧4 h；Ⅵ组（复氧2组）：常氧培养16 h，缺氧8 h、复氧8 h；Ⅶ组（复氧3组）：常氧培养16 h，缺氧8 h、复氧12 h；Ⅷ组（转基因缺氧2组）：转基因后常氧培养16 h，缺氧20 h。ELISA法测定培养液VEGF蛋白含量；细胞免疫荧光染色及RT-PCR分别检测细胞内VEGF蛋白及VEGF165 mRNA的表达。结果:95%的培养心肌细胞可见自律搏动，cTn-I染色阳性率为86%；病毒转染率约为87%。Ⅳ、Ⅴ、Ⅷ组培养液中VEGF蛋白含量显著高于其它各组（P<0.01），细胞免疫荧光VEGF蛋白染色呈阳性；RT-PCR测定显示，Ⅳ、Ⅴ及Ⅷ组可见484 bp目的条带。结论：rAAV-HRE9-hVEGF165可成功地转染原代培养心肌细胞，在缺氧环境下，受HRE的调控，VEGF165 mRNA及VEGF165蛋白可有效表达，而在常氧状态下，目的基因的表达及蛋白合成即行中止。

Regulation of hypoxic response elements to expression of hVEGF165 gene transferred to cardiomyocytes under anoxic and normoxic conditions

AIM:To investigate effects of hypoxic response elements (HRE) on expression of hVEGF165 gene transferred to myocardiocyte under anoxic and normoxic conditions in vitro.METHODS:Myocardiocytes from neonatal SD rats were isolated and cultured in serum-free medium.The r-AAV vector packaged with 293T cells was used to transfer cultured myocardiocytes.Myocardiocytes were divided into eight groups: Group Ⅰ: myocardiocytes were cultured for 24 hours under normoxic conditions as control;Group Ⅱ: cells was cultured under hypoxia for 8 hours;Group Ⅲ: infected cells were cultured for 24 hours under normoxic conditions;Group Ⅳ: infected cells were cultured under hypoxia for 8 hours;GroupⅤ: infected cells were cultured under hypoxia for 8 hours and normoxia for 4 hours;GroupⅥ: infected cells were cultured under hypoxia for 8 hours and normoxia for 8 hours;GroupⅦ: infected cells were cultured under hypoxia for 8 hours and normoxia for 12 hours;Group Ⅷ: infected cells were cultured under hypoxia only for 20 hours.hVEGF165 protein was quantified from culture medium using ELISA,hVEGF165 protein in myocardiocytes was detected with immunofluorescence and expression of hVEGF165 mRNA was also determined by RT-PCR.RESULTS:95% myocardiocytes showed beating rhythmically with 86% of cTn-I positive staining.87% virual transferred efficiency was achieved.The contents of hVEGF165 protein in group Ⅳ,Ⅴ and Ⅷ were higher than those in other groups (P<0.01).Immunofluorescence positive cells were observed in group Ⅳ,Ⅴ and group Ⅷ.RT-PCR revealed that a 484 bp strip was also found in the same groups.CONCLUSION:rAAV-HRE9-hVEGF165 vector infected cultured myocardiocyte successfully.Under hypoxia,expression of hVEGF165mRNA and hVEGF165 protein were regulated by HRE,whereas under normoxic conditions the expression of hVEGF165 mRNA and hVEGF165 protein were ceased.