X射线全身照射诱导小鼠胸腺Egr-1和Egr-4基因表达水平的实时定量RT—PCR分析

Quantitative detection of Egr-1 and Egr-4 gene expression in mice thymus after whole-body irradiation with X-rays by real-time RT-PCR

目的应用实时定量RT—PCR技术检测X射线全身照射诱导小鼠胸腺Egr-1和Egr-4基因的表达变化。方法小鼠接受X射线全身照射后4和24h，提取胸腺mRNA，以GAPDH作为内参基因，利用实时定量RT—PCR检测方法，探讨Egr-1和Egr-4基因的相对表达量与不同照射剂量之间的关系。同时计数骨髓嗜多染红细胞微核率作为辐射生物剂量参照。结果Egr-1和Egr-4基因表达量在0．5～6Gy全身照射后4和24h均与照射剂量之间存在显著的相关性（r=0．974，0．987，0．978，0．999，P〈0．01），其剂量效应曲线可拟合成线性平方方程。各剂量点Egr-1和Egr-4基因表达量与骨髓嗜多染红细胞微核率高度相关（r=0．866、0．947、0．983、0．835，P〈0．05）。进一步分析表明，照射后4hEgr-4基因表达不仅剂量效应关系良好，且增幅最为明显，并与骨髓嗜多染红细胞微核率的剂量效应曲线相平行。结论实时定量RT—PCR技术检测Egr-4基因的早期表达有可能成为建立大批量、快速辐射生物剂量估算方法的候选者。

Objective To investigate the changes of Egr-1 and Egr-4 gene expression in mice thymus after whole-body irradiation （WBI）with X-rays by real-time quantitative reverse transcriptionpolymerase chain reaction（ QRT-PCR）. Methods The mRNA was isolated from mice thymus 4 and 24 h after WBI with 0-6 Gy of X-ray irradiation. The changes of Egr-1 and Egr-4 gene expression 4 and 24 h post irradiation were examined with QRT-PCR. Parallelled counts of micronucleus rate in bone marrow polychromatic erythrocytes（PCE）was made as a reference radiation biodosimetric control. Results The relative expression of Egr-1 and Egr-4 genes at 4 and 24 h after WBI with 0. 5 to 6 Gy was changed with the dose （ r = 0. 974,0. 987,0. 978,0. 999, P 〈 0.01 ）. At all dose points the relative expression of Egr-1 and Egr4 genes was highly correlated with the micronucleus rate of bone marrow PCE （ r = 0. 866,0. 947, 0. 983,0. 835, P 〈 0. 05 ）. The dose-effect relationship could be fitted into linear-quadratic model. The expression of Egr-4 gene was significantly increased at 4 h post irradiation and best correlated with PCE micronucleus rate. Conclusions QRT-PCR assay of early expression of Egr-4 gene might be a candidate for fast, high-throughput radiation biodosimetry.