中文摘要：

目的 在体外培养的PC12细胞中观察低氧反应元件（HRE）介导的神经营养因子-3（NT-3）对低氧反应性表达上调及其对低氧诱导的PC12细胞凋亡的影响。方法 用分子生物学方法将5拷贝HRE（5HRE）和NT-3克隆入反转录病毒载体中构建HRE介导的低氧调控表达载体,并转导入PC12细胞,ELISA法检测NT-3的表达和分泌,TUNEL法检测细胞凋亡,Western blotting检测p38丝裂原活化蛋白激酶（p38MAPK）和Caspase-3激活情况。结果 成功构建重组反转录病毒载体,并将外源基因转导入PC12细胞中（PC12-NT3-EGFP、PC12-5HRE-NT3-EGFP和PC12-5HRE-EGFP）。在正常条件培养下,PC12-5HRE-NT3-EGFP细胞中NT-3表达水平较低,但在低氧处理后,NT-3表达明显升高（n=3,P〈0.05）。在低氧处理后,与PC12细胞组相比,PC12-5HRE-NT3-EGFP组中细胞凋亡明显减少（n=3,P〈0.05）,且p38 MAPK和Caspase-3磷酸化也明显减少（n=3,P〈0.05）。结论 在PC12细胞中HRE介导的低氧反应性调控NT-3的表达上调可以对PC12细胞产生保护作用。

英文摘要：

Objective To investigate the controlled expression of neurotrophin-3 （NT-3） by HRE under hypoxic conditions and determine the protective effects of conditionally expressed NT-3 on hypoxia-induced apoptosis in PC12 cells. Methods Five copies of the HRE （5HRE） and NT-3 were employed to construct a therapeutic vector, and transferred into PC12 ceils. Expression and secretion of NT-3 were detected by ELISA. Apoptosis of PC12 cells induced by hypoxia was assayed by TUNEL. Activation of p-38 and Caspase-3 was detected by Western blotting. Results The retroviral vectors were successfully constructed and transfected into PC12 cells to produce gene transferred cells, PC12-NT3-EGFP, PCt2-SHRE-NT3-EGFP and PC12-SHRE-EGFP. Compared with normal conditions, in which NT-3 was expressed at low levels, the expression of NT-3 significantly increased under hypoxic conditions in PC12-5HRE-NT3-EGFP （n = 3, P 〈 0. 05）. The conditional adjustment of NT-3 expression by 5HRE significantly reduced apoptosis induced by hypoxia in PC12-SHRE-NT3-EGFP （ n = 3, P 〈 O. 05）. In addition, the hypoxia-induced phosphorylation of both p38 and Caspase-3 activities was decreased in PC12-SHRE-NT3-EGFP under hypoxic conditions （ n = 3, P 〈 O. 05 ）. Conclusion Up- regulated expression of NT-3 mediated by hypoxia response element in response to hypoxia in PC12 cells can protect PC12 ceils against hypoxia-induced apoptosis.