EVIDENCE FOR DEFECTIVE REPAIR OF CYCLOBUTANE PYRIMIDINE DIMERS WITH NORMAL REPAIR OF OTHER DNA PHOTOPRODUCTS IN A TRANSCRIPTIONALLY ACTIVE GENE TRANSFECTED INTO COCKAYNE SYNDROME CELLS
EVIDENCE FOR DEFECTIVE REPAIR OF CYCLOBUTANE PYRIMIDINE DIMERS WITH NORMAL REPAIR OF OTHER DNA PHOTOPRODUCTS IN A TRANSCRIPTIONALLY ACTIVE GENE TRANSFECTED INTO COCKAYNE SYNDROME CELLS
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DOI：
10.1016/0921-8777(91)90032-k
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发表时间：
1991-11-01
期刊：
影响因子：
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通讯作者：
KRAEMER, KH
中科院分区：
文献类型：
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作者：
BARRETT, SF;ROBBINS, JH;KRAEMER, KH
科凯恩综合征 (CS) 和色素性干皮病 (XP) 是常染色体隐性遗传疾病，具有临床和细胞对紫外线辐射过敏的症状，它们在整个基因组中修复紫外线 DNA 光产物的能力不同：CS 的修复正常，XP 的修复缺陷。 为了表征整个基因组中的 DNA：CS 中的正常修复，XP 中的缺陷修复。 为了表征 CS 中活性基因的 DNA 修复缺陷，我们测量了 CS 和 XP 患者的细胞在主动转录质粒的氯霉素乙酰转移酶 (cat) 基因中重新激活 2 种主要类型的紫外线诱导的 DNA 损伤的能力，即光可再激活（即环丁烷嘧啶二聚体）和非光可再激活（主要是嘧啶-(6-4)嘧啶酮光产物）表达载体pRSV-cat。 用该质粒瞬时转染来自 4 名正常人、3 名 CS 患者和 2 名 XP 患者的 Epstein-Barr 病毒转化的淋巴母细胞系，并测定细胞提取物中的 cat 活性。 当用紫外线照射的质粒转染细胞时，CS和XP细胞中的cat表达异常降低。 当转染前通过光再激活去除紫外线照射质粒中的环丁烷嘧啶二聚体时，CS 系中的 cat 表达达到正常水平，但 XP 系中未达到正常水平。 这些数据表明 XP 和 CS 细胞都无法正常修复阻碍 cat 转录的环丁烷嘧啶二聚体光产物。 然而，CS（而非 XP）细胞可以正常修复其他紫外线诱导的阻碍转录的光产物。 CS细胞而非XP细胞修复这些非二聚体光产物的能力表明活性基因修复机制以不同于非二聚体光产物的方式处理环丁烷嘧啶二聚体。
Cockayne syndrome (CS) and xeroderma pigmentosum (XP), autosomal recessive diseases with clinical and cellular hypersensitivity to UV radiation, differ in ability to repair UV DNA photoproducts in their overall genome: normal repair in CS, defective repair in XP. In order to characterize a DNA in their overall genome: normal repair in CS, defective repair in XP. In order to characterize a DNA repair defect in an active gene in CS, we measured the capacity of cells from patients with CS and XP to reactivate 2 major types of UV-induced DNA damage, photoreactivatable (i.e., cyclobutane pyrimidine dimers) and non-photoreactivatable (primarily pyrimidine-(6-4)pyrimidone photoproducts), in the actively transcribing chloramphenicol acetyltransferase (cat) gene of the plasmid expression vector pRSV-cat. Epstein-Barr virus-transformed lymphoblast lines from 4 normal persons and from 3 patients with CS and from two with XP were transiently transfected with the plasmid, and the cat activity in cell extracts was determined. When the cells were transfected with UV-irradiated plasmid, cat expression was abnormally decreased in both the CS and XP cells. When the cyclobutane pyrimidine dimers in the UV-irradiated plasmid were removed by photoreactivation prior to transfection, cat expression in the CS, but not in the XP, lines reached normal levels. These data imply that both the XP and CS cells are unable to repair normally the cyclobutane pyrimidine dimer photoproducts which blocks transcription of cat. However, the CS, but not XP, cells can repair normally the other UV-induced photoproducts which block transcription. The ability of CS, but not XP, cells to repair these non-dimer photoproducts indicates that the active gene repair mechanism treats the cyclobutane pyrimidine dimer differently from the non-dimer photoproducts.