摘要
Objective The radiation sensitive gene rad 21 of Schizosaccharomyces pombe is involved in the repair of double-stranded breaks in DNA and is essential for mitotic growth. The hHR21 sp gene is its human homologue. In an attempt to investigate the role of hHR21 sp in DNA repair, we studied the effects of UV and γ-ray irradiation on hHR21 sp gene expression in normal human peripheral blood cells, and non-iradiated peripheral and bone marrow cells from Fanconi anemia (FA) patients who have shown DNA repair deficiency.Methods Total steady state RNA was extracted from peripheral blood cells and bone marrow. RNA transcripts were quantified after RT-PCR and Southern blot, phosphoimmage and autoradiogram analysis. The results were compared with control groups. Results hHR21 sp expression was significantly increased from 3?h to 9?h after UV irradiation in peripheral blood cells from normal subjects at doses of 40-80?j/m 2 (P<0.05). hHR21 sp was also up-regulated by γ-ray irradiation at 6?h to 9?h at dose of 1 to 5?Gy (P<0.01), which was more significant than the UV irradiation. In the non-irradiated FA patient group, hHR21 sp expression was decreased in bone marrow hematopoietic cells (P<0.05). After activation by PHA and IL-2, there was still a significant depression in expression by the FA patients peripheral blood cells compared with control groups (P<0.05). Conclusion hHR21 sp was up-regulated at doses and times irradiated at the range tested in normal peripheral blood cells, and is more affected by γ-ray irradiation than UV irradiation. FA patient bone marrow hematopoietic cells and peripheral blood mononuclear cells showed down-regulation of hHR21 sp expression. The results imply that defects in DNA repair via hHR21 sp expression may play an important role in the pathogenesis of FA syndrome.
目的 检测UV和γ辐射对正常人外周血单核细胞的hHR2 1sp基因转录表达水平及hHR2 1sp在范可尼贫血(FanconisAnemiaFA)骨髓造血细胞和激活后的外周血单核细胞的转录表达情况 ,并分析hHR2 1sp基因在FA贫血发病机制中的作用。方法 对范可尼贫血骨髓造血细胞和激活后的外周血单核细胞和正常人外周血单核细胞在UV或γ辐射后不同时间提取细胞总RNA ,通过RT PCR、Southern杂交、以β actin为内参照放射影像对hHR2 1sp基因的转录表达水平进行检测 ,比较FA骨髓造血细胞与对照组差异和激活前后FA外周血单核细胞hHR2 1sp基因的表达水平。结果 正常人外周血单核细胞与对照组比较在 80j/m2 UV辐射hHR2 1sp表达于 3h开始增加 ;在 6h表达水平最高 ,与正常对照有 2倍差异 (P <0 0 5 ) ;而γ 辐射 5Gy辐射 6h增加明显 ,在 9h后有所降低与正常对照有 2倍多差异 (P <0 0 1)。可见FA病人骨髓造血细胞和对照组的hHR2 1sp基因表达水平有明显差异 (P <0 0 5 )。实验发现在激活后对FA病人外周血单核细胞检测 ,hHR2 1sp基因表达较对照组PB MNC降低达 2倍之多 (P <0 0 5 )。结论 hHR2 1sp表达水平在一定剂量电离辐射范围内随辐射剂量增加而增高 ,且对γ 辐射较UV辐射敏感 ,FA病人骨髓造血细胞和对照组的hHR2 1sp基因表?
