p53-mediated transcription induces resistance of DNA to UV inactivation.
p53-mediated transcription induces resistance of DNA to UV inactivation.
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p53 介导的转录诱导 DNA 对紫外线失活的抵抗力。
DOI：
10.1038/sj.onc.1201951
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发表时间：
1998
期刊：
影响因子：
--
通讯作者：
Simmons,DT
中科院分区：
文献类型：
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作者：
Huang,J;Logsdon,N;Schmieg,FI;Simmons,DT
用紫外光照射的氯霉素乙酰转移酶(CAT)报告质粒(PRGC)，研究了p53依赖的转录在诱导DNA修复中的可能作用。FOS。CAT)，含有一个由共同的P53结合位点驱动的最小FOS启动子，转化到P53阴性的小鼠细胞系[(10)1]。当P53表达载体(PSV.将P53)共转染入这些细胞，即使在长时间的紫外线照射后，CAT的表达水平仍保持不变。与pSV2相比，pSV2中CAT的表达。在其SV40启动子中缺少P53反应元件的CAT，在没有或存在WT P53表达的情况下，在紫外线照射后下降得更快。当报告基因在ras、β-肌动蛋白或fos启动子的控制下时，其他三个结构物也观察到类似的急剧下降。在32℃下，构成表达小鼠P53的温度敏感突变体(135 AV)的小鼠细胞(A1-5)也产生了更高水平的紫外线照射的pRGC表达的酶。FOS。CAT活性高于紫外线照射的pSV2。猫。紫外光照射的pRGC中环丁烷嘧啶二聚体的频率。FOS。用T4 Endo V测定CAT，根据不同时间紫外线照射下的泊松分布计算CAT编码链未受损的概率。观察到照射后pSV2中CAT的相对表达水平。CAT和pRGC。FOS。P53缺失的CAT与上述数字一致。这些结果表明，WTP53介导的转录引导转录的DNA对紫外线灭活的抗性，并重新激活报告基因。此外，一些保持接近正常转录激活能力的p53单点替换突变体在紫外线照射后失去了延长CAT基因表达的能力。相反，其他转录活性降低的突变体保留了这种能力。这表明，尽管对紫外线失活的抗性依赖于转录，但这两种活性在遗传上是不同的。这些数据综合起来，表明依赖于p53的过程对紫外线损伤的DNA的转录促进了它的修复。
A possible role of p53-dependent transcription in the induction of DNA repair was explored by transfecting a UV-irradiated chloramphenicol acetyl transferase (CAT) reporter plasmid (pRGC. FOS. CAT), containing a minimal FOS promoter driven by a consensus p53 binding site, into a p53 negative-mouse cell line [(10) 1]. When a p53-expressing plasmid (pSV. p53) was cotransfected into these cells, CAT expression levels persisted even after prolonged UV irradiation. In comparison, CAT expression from pSV2. CAT, which lacks a p53-responsive element in its SV40 promoter, dropped off much more precipitously after UV irradiation in the absence or presence of WT p53 expression. A similar sharp drop was observed with three other constructs when the reporter gene was under the control of the ras, β-actin or fos promoter. Mouse cells (A1-5) that constitutively express a temperature-sensitive mutant (135 AV) of mouse p53 also generated, at 32 C, higher levels of enzyme expressed from UV-irradiated pRGC. FOS. CAT than from UV-irradiated pSV2. CAT. The frequency of cyclobutane pyrimidine dimers in UV-irradiated pRGC. FOS. CAT was determined with T4 endo V, and the probability of having an undamaged CAT coding strand was calculated by the Poisson distribution for various times of UV-irradiation. The observed relative CAT expression levels from irradiated pSV2. CAT and pRGC. FOS. CAT in the absence of p53 were consistent with those numbers. These results show that WT p53-mediated transcription directs a resistance of the transcribed DNA to UV inactivation and reactivates the reporter gene. Furthermore, some single point substitution mutants of p53 that maintain a near normal ability to activate transcription had lost their ability to extend CAT gene expression after UV irradiation. Conversely, other mutants with reduced transcriptional activity retained this ability. This indicates that although resistance to UV inactivation is transcriptionally-dependent, these two activities are genetically distinct. These data, taken together, suggest that the transcription of UV-damaged DNA by a p53-dependent process promotes its repair.