X射线照射后小鼠血清、小肠和心脏组织中游离泛素水平的变化

X-ray irradiation modulates the expressions of free ubiquitin in the serum, small intestine, and heart of C57 BL/6N mice

目的：研究X射线照射对C57 BL/6N小鼠血清、小肠和心脏组织中游离泛素（ free UB）水平的影响。方法应用ELISA法定量检测受照小鼠血清、小肠、心脏组织匀浆中free UB的含量；Western blot法检测小鼠组织中free UB蛋白的表达；RT-PCR法检测小鼠组织中free UB编码基因UBB的mRNA水平。结果与未照射组相比，照射后24和48 h，小鼠血清中free UB水平随照射剂量的增加而增加（F＝183.1、435.3，P＜0.01）；5和10 Gy照射后，血清中free UB随照射后时间的延长而增加（F＝131.4、442.9，P＜0.01）。与未照射组相比，10 Gy X射线照射后24 h，小肠中free UB蛋白表达水平和free UB编码基因UBB的mRNA表达水平均明显增加（ t＝-18.7、-10.1，P＜0.01）；而心脏组织中free UB蛋白表达水平和UBB的mRNA表达水平均无明显改变（ t＝-2.0、3.1，P ＞0.05）。结论通过诱导辐射敏感组织小肠中free UB蛋白表达水平增加，电离辐射能够增加小鼠血清中free UB的表达量；free UB水平可能与组织的辐射敏感性和组织受损程度有关。

Objective To investigate the effect of X-ray irradiation on the expression of free ubiquitin in the serum, small intestine, and heart tissues of C57 BL/6N mice. Methods The amount of free ubiquitin protein in the serum and tissue homogenates was analyzed quantitatively with ELISA and Western Blotting assay. The mRNA expressions of free ubiquitin in the tissues were detected by RT-PCR. Results At 24 or 48 h after radiation, the free ubiquitin level in the serum and small intestine tissue increased asymptotically with increasing of radiation dose （F=183.1, 435.3, P 〈0.01）. After 5 and 10 Gy X-ray irradiation, the concentration of serum free ubiquitin increased asymptotically with the extended response time （F=131.4, 442.9, P〈0.01）. Compared with the normal control group, at 24 h after 10 Gy X-ray irradiation, the expressions of free ubiquitin protein and mRNA in small intestine tissue were significantly up-regulated （t= -18.7, -10.1, P〈0.01）. However, there was no difference in the expressions of free ubiquitin protein and mRNA in the heart tissues between irradiated and nonirradiated groups （t = -2.0, 3.1, P 〉0.05）. Conclusions Because of the high expressions of free ubiquitin protein in the radiosensitive mice tissues, X-ray radiation could increase the concentration of free ubiquitin in serum. The changes of free ubiquitin may be related to cellular radiosensitivity and tissue injury.