Mezzina M, Eveno E, Chevallier-Lagente O, Benoit A, Carreau M, Vermeulen W, Hoeijmakers J H, Stefanini M, Lehmann A R, Weber C A
Laboratory of Molecular Genetics, UPR42 CNRS IFC H01, Villejuif, France.
Carcinogenesis. 1994 Aug;15(8):1493-8. doi: 10.1093/carcin/15.8.1493.
Trichothiodystrophy (TTD) is a rare genetic disease with heterogeneous clinical features associated with specific deficiencies in nucleotide excision repair. Patients have brittle hair due to a reduced content of cysteine-rich matrix proteins. About 50% of the cases reported in the literature are photosensitive. In these patients an altered cellular response to UV, due to a specific deficiency in nucleotide excision repair, has been observed. The majority of repair-defective TTD patients have been assigned by complementation analysis to group D of xeroderma pigmentosum (XP). Recently, the human excision repair gene ERCC2 has been shown to correct the UV sensitivity of XP-D fibroblasts. In this work we describe the effect of ERCC2 on the DNA repair deficient phenotype of XP-D and on two repair-defective TTD cell strains (TTD1VI and TTD2VI) assigned by complementation analysis to group D of XP. ERCC2 cDNA, cloned into a mammalian expression vector, was introduced into TTD and XP fibroblasts via DNA-mediated transfection or microneedle injection. UV sensitivity and cellular DNA repair properties, including unscheduled DNA synthesis and reactivation of a UV-irradiated plasmid containing the chloramphenicol acetyltransferase reporter gene (pRSVCat), were corrected to wild-type levels in both TTD and XP-D cells. These data show that a functional ERCC2 gene is sufficient to reestablish a wild-type DNA repair phenotype in TTD1VI and TTD2VI cells, confirming the genetic relationship between TTD and XP-D. Furthermore, our findings suggest that mutations at the ERCC2 locus are responsible for causing a similar phenotype in TTD and XP-D cells in response to UV irradiation, but produce quite different clinical symptoms.
毛发硫营养不良症（TTD）是一种罕见的遗传性疾病，具有异质性临床特征，与核苷酸切除修复的特定缺陷相关。由于富含半胱氨酸的基质蛋白含量降低，患者的头发很脆。文献报道的病例中约50%对光敏感。在这些患者中，由于核苷酸切除修复存在特定缺陷，已观察到细胞对紫外线的反应发生改变。大多数修复缺陷型TTD患者通过互补分析被归类为着色性干皮病（XP）的D组。最近，已证明人类切除修复基因ERCC2可纠正XP-D成纤维细胞的紫外线敏感性。在这项工作中，我们描述了ERCC2对XP-D的DNA修复缺陷表型以及通过互补分析被归类为XP的D组的两种修复缺陷型TTD细胞系（TTD1VI和TTD2VI）的影响。克隆到哺乳动物表达载体中的ERCC2 cDNA通过DNA介导的转染或微针注射被导入TTD和XP成纤维细胞。在TTD和XP-D细胞中，紫外线敏感性和细胞DNA修复特性，包括非定标DNA合成以及含有氯霉素乙酰转移酶报告基因（pRSVCat）的紫外线照射质粒的再激活，均被纠正至野生型水平。这些数据表明，功能性ERCC2基因足以在TTD1VI和TTD2VI细胞中重新建立野生型DNA修复表型，证实了TTD与XP-D之间的遗传关系。此外，我们的研究结果表明，ERCC2基因座的突变是导致TTD和XP-D细胞在紫外线照射下出现相似表型的原因，但会产生截然不同的临床症状。
