CROSS-LINK REPAIR IN HUMAN CELLS AND ITS POSSIBLE DEFECT IN FANCONIS ANEMIA CELLS
CROSS-LINK REPAIR IN HUMAN CELLS AND ITS POSSIBLE DEFECT IN FANCONIS ANEMIA CELLS
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DOI：
10.1016/0022-2836(77)90227-3
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发表时间：
1977-01-01
影响因子：
5.6
通讯作者：
SASAKI, MS
中科院分区：
文献类型：
--
作者：
FUJIWARA, Y;TATSUMI, M;SASAKI, MS
用克隆形成能力、碱性蔗糖沉淀法和羟基磷灰石层析法研究了双功能丝裂霉素C、单功能去氨甲酰丝裂霉素C和紫外线照射对正常人色素性干皮病和范可尼S贫血细胞DNA损伤的差异修复作用。尽管对紫外线和DMC的抗性正常，但四个FA细胞株对MC杀伤的敏感性约为正常人类细胞的5-15倍。XP细胞由于缺乏切除修复能力，对紫外线和DMC的杀伤高度敏感，但其存活MC和修复MC链间交联的能力出人意料地接近正常。在测定DNA在碱性蔗糖梯度中的沉积速度的实验中，正常细胞和XP细胞在MC处理后显示出单链切割的证据。在FA菌株中，MC共价交联的DNA的沉降速度比未经处理的对照快2.5倍，并且由于没有半切除交联链，在培养后保持不变。FA细胞，而不是XP细胞，具有用DMC单加合物切割DNA的正常能力。羟基磷灰石层析显示变性后的MC交联DNA具有可逆的双螺旋性质。正常和XP细胞在MC后孵育过程中失去这种可逆性，这是由于以一级动力学(半衰期=2小时)去除交联键的结果。所研究的3个FA品系的交联链去除率比正常细胞和XP细胞低2-8倍，表明FA品系的修复缺陷存在差异。尽管FA细胞对紫外线诱导的嘧啶二聚体和DMC单加合物具有正常的修复机制，但在MC诱导的链间交联的半切除修复中可能存在不同程度的缺陷，反之亦然。
The differential repair was studied of DNA lesions induced by bifunctional mitomycin C [MC] monofunctional decarbamoyl mitomycin C [DMC] and UV irradiation in normal human xeroderma pigmentosum [XP] and Fanconi''s anemia [FA] cells using assays for the survival of clone-forming ability, alkaline sucrose sedimentation and hydroxyapatite chromatography of DNA. Four FA cell lines exhibited about 5-15 times higher sensitivity to MC killing, despite normal resistance to UV and DMC, than did normal human cells. The XP cells were highly sensitive to UV and DMC killings due to their deficiency in excision repair, but the cells unexpectedly had an almost normal capacity for surviving MC and repairing the MC interstrand cross-links. In experiments to determine the sedimentation velocity of the DNA in alkaline sucrose gradients, normal and XP cells showed evidence for single-strand cutting following MC treatment. The sedimentation velocity of the DNA covalently cross-linked by MC in an FA strain was 2.5 times faster than that of the untreated control, and remained unaltered during post-incubation due to the lack of half-excision of cross-links. FA cells, but not XP cells, had the normal ability to incise DNA with the DMC monoadducts. Hydroxyapatite chromatography revealed the reversibly bihelical property of MC cross-linked DNA after denaturation. Normal and XP cells lost such reversibility during post-MC incubation as the result of cross-link removal with 1st-order kinetics (half-life = 2 h). The 3 FA lines studied exhibited 2-8-fold reduced rates of cross-link removal than normal and XP cells, indicating a difference in the repair deficiency of the FA strain. FA cells may have different levels of deficiency in half-excision repair of interstrand cross-links induced by MC, despite having normal mechanisms for repair of UV-induced pyrimidine dimers and DMC monoadducts, and vice versa in XP cells.