Epigenetics and Genomic Instability Laboratory, Instituto de Investigaciones Biológicas Clemente Estable, Montevideo, Uruguay.
Mutat Res. 2010 Aug 14;701(1):98-102. doi: 10.1016/j.mrgentox.2010.02.008. Epub 2010 Feb 20.
Cells with a transcription coupled repair (TCR) deficiency are characterized by a higher sensitivity to UVC irradiation and by an increase in apoptosis and chromosomal aberration frequencies. It has been claimed that the higher frequency of chromosomal aberrations results from the transcription blockage caused by UVC-lesions located in the transcribed strands of the genome. The distribution of chromosome breakpoints in euchromatic and heterochromatic regions of the X chromosome from TCR deficient and proficient Chinese hamster cell lines was studied. Most UVC-induced breakpoints occurred in euchromatic regions of the X chromosome in both cell lines. No increase of UVC-induced breakpoints in the euchromatic region of the UV61 X chromosome was observed, indicating that TCR failure alone cannot be responsible for the increased frequency of chromosomal aberrations. Differential chromatin remodeling in the TCR defective cell line is proposed as a possible mechanism involved in the distribution of UVC-induced breakpoints along the Chinese hamster X chromosome. A similar explanation for the increase of UVC-induced chromosomal aberrations in TCR defective cells is given.
具有转录偶联修复（TCR）缺陷的细胞的特征是对 UVC 照射更敏感，凋亡和染色体畸变频率增加。有人声称，染色体畸变的更高频率是由于 UVC 损伤位于基因组转录链上而导致的转录受阻所致。研究了 TCR 缺陷和功能正常的中国仓鼠细胞系中 X 染色体常染色质和异染色质区域的染色体断裂点分布。在两条细胞系中，大多数 UVC 诱导的断裂点发生在 X 染色体的常染色质区域。未观察到 UV61X 染色体常染色质区域 UVC 诱导断裂点的增加，表明 TCR 失败本身不能解释染色体畸变频率的增加。提出 TCR 缺陷细胞系中差异染色质重塑可能是 UVC 诱导的断裂点沿中国仓鼠 X 染色体分布的机制之一。对于 TCR 缺陷细胞中 UVC 诱导的染色体畸变增加，给出了类似的解释。
