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目的研究辐射诱导下Egr1基因启动子调控腺病毒介导的Smad7基因在C57BL小鼠肺内表达与放射剂量及放射后时相间的关系。方法将Egr1基因启动子的放射敏感元件和Smad7cDNA包装到复制缺陷型腺病毒内,制备成AD.EgrSmad7。小鼠气管内给AD.EgrSmad7,24h后单次全胸照射。324只小鼠随机分组进入实验,γ线8Gy照射后不同时间取肺组织测定Smad7蛋白含量,研究照射后Smad7基因肺内表达的时效关系。108只小鼠随机分组进入实验,以不同剂量照射后5h取肺组织测定Smad7蛋白含量,研究Smad7基因肺内表达与放射剂量的关系。采用Westernblot印迹法检测小鼠肺组织Smad7蛋白表达。结果γ线照射可明显诱导Egr1基因启动子调控腺病毒介导的Smad7基因在C57BL小鼠肺内表达,与对照组相比差异有统计学意义(P<0.01)。Smad7基因表达量与照射剂量和照射后间隔时间有关,单次照射0～12Gy间Smad7蛋白表达量随剂量升高而增加,15Gy时下降。照射后2～9hSmad7蛋白表达量最高(P<0.05),而后降低,15h降至接近正常水平。结论以腺病毒为载体,经射线诱导Egr1基因启动子能够调控Smad7基因体内表达,Smad7基因表达量与放射剂量及放射后间隔时间有关。
Objective To study the relationship between the expression of adenovirus-mediated Smad7 gene in lungs of C57BL mice induced by radiation-induced Egr1 promoter and its radiation dose and post-irradiation phase. Methods Egr1 gene promoter and Smad7cDNA were packaged into replication-deficient adenovirus to prepare AD.EgrSmad7. Intrathecal administration of AD.EgrSmad7 mice 24 hours after a single full chest irradiation. 324 mice were randomized into the experiment. The levels of Smad7 protein in the lung tissue were measured at different time after 8Gy irradiation, and the relationship between the expression of Smad7 gene in lung and the lung was studied. One hundred and eighty mice were randomly divided into experimental groups. The levels of Smad7 protein in lung tissue were measured 5h after irradiation with different doses to study the relationship between the expression of Smad7 gene and the radiation dose. Western blotting was used to detect Smad7 protein expression in mouse lung tissue. Results γ ray irradiation could obviously induce the Egr1 gene promoter to regulate the expression of adenovirus-mediated Smad7 gene in the lung of C57BL mice. The difference was statistically significant compared with the control group (P <0.01). The expression level of Smad7 was related to the irradiation dose and the time interval after irradiation. The expression of Smad7 protein increased with the increase of dose from 0 to 12 Gy in a single irradiation and decreased at 15 Gy. The expression of Smad7 protein was the highest at 2 ~ 9h after irradiation (P <0.05), then decreased, and reached the normal level at 15h. Conclusion The adenovirus vector can regulate the expression of Smad7 gene by the radiation-induced Egr1 gene promoter. The expression of Smad7 gene is related to the radiation dose and the time interval after irradiation.