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本文观察了15戈瑞γ-射线全身照射后,大鼠小肠粘膜上皮细胞核体外转录活性,从染色质结合的RNA聚合酶和可溶性RNA聚合酶活性变化探讨辐射对核转录活性的抑制机理。实验结果表明:(1)照后2小时、8小时和24小时,核转录活性分别下降22.7％、20.8％和28.2％;(2)染色质结合的RNA聚合酶活性变化与细胞核转录活性变化基本平行,提示核转录活性降低与核内染色质损伤有关;(3)照后24小时,核分离的可溶性RNA聚合酶抑制58％,提示辐射至少部分是通过抑制RNA聚合酶而影响细胞核转录活性;(4)在细胞核和分离的RNA聚合酶都观察到RNA聚合酶Ⅱ抑制程度大于RNA聚合酶Ⅰ和酶Ⅲ,酶活性下降主要表现在RNA聚合酶Ⅱ提示不同类RNA聚合酶对辐射的敏感性不同,酶Ⅱ对辐射更敏感。
In this paper, we observed the in vitro transcription activity of rat intestinal mucosal epithelial cells after γ-ray irradiation of 15 Gy and the inhibitory mechanism of radiation on nuclear transcription activity from the changes of chromatin-bound RNA polymerase and soluble RNA polymerase activity. The results showed that: (1) Nuclear transcription activity decreased by 22.7%, 20.8% and 28.2% at 2 h, 8 h and 24 h after irradiation; (2) The changes of chromatin-binding RNA polymerase activity and nuclear transcriptional activity (3) At 24 hours after irradiation, soluble nuclear RNA polymerase was inhibited by 58%, indicating that radiation at least partially affects nuclear transcription activity by inhibiting RNA polymerase; (4) The inhibition of RNA polymerase Ⅱ in nucleus and isolated RNA polymerase was higher than that of RNA polymerase Ⅰ and Ⅲ, and the decrease of enzyme activity was mainly reflected in the sensitivity of RNA polymerase Ⅱ to different types of RNA polymerase In contrast, enzyme II is more radiation sensitive.