UVA-induced cyclobutane pyrimidine dimers form predominantly at thymine-thymine dipyrimidines and correlate with the mutation spectrum in rodent cells
UVA-induced cyclobutane pyrimidine dimers form predominantly at thymine-thymine dipyrimidines and correlate with the mutation spectrum in rodent cells
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DOI：
10.1093/nar/gkg402
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发表时间：
2003-06-01
影响因子：
14.9
通讯作者：
Sage, E
中科院分区：
文献类型：
--
作者：
Rochette, PJ;Therrien, JP;Sage, E
采用连接介导的PCR来定量用UVA（340-400 nm）、UVB（295-320 nm）、UVC（254 nm）或模拟日光（SSL; λ>295 nm）照射后中国仓鼠卵巢（CHO）细胞中腺嘌呤磷酸核糖基转移酶（aprt）基因座的外显子2在核苷酸分辨率下的环丁烷嘧啶二聚体（CPD）形成。然后将每个波长区域的所得DNA损伤光谱与先前在相同遗传靶标中产生的相应突变光谱进行比对。由UVC、UVB或SSL诱导的CPD形成的DNA序列特异性非常相似，即，在每种情况下，在TT、TC、CT和CC位点形成的这种光产物的总体相对比例分别为28%、26%、16%和30%。此外，注意到CPD损伤热点的精确位置与嘧啶运行中主要由C->T和CC->TT转换组成的“UV特征”突变热点的精确位置之间存在明确的对应关系。然而，UVA暴露后，与UVC、UVB或SSL的上述情况形成强烈对比，TT部位产生CPD的频率远高于TC、CT或CC部位（分别为57%和18%、11%和14%）。这种CPD沉积模式与UVA照射的CHO细胞中相对于TT二嘧啶回收的突变的惊人高比例很好地相关。我们的研究结果直接牵连CPD作为一个主要的promutagenic DNA光产物诱导的UVA在啮齿动物细胞中特异性。
Ligation-mediated PCR was employed to quantify cyclobutane pyrimidine dimer (CPD) formation at nucleotide resolution along exon 2 of the adenine phosphoribosyltransferase (aprt) locus in Chinese hamster ovary (CHO) cells following irradiation with either UVA (340-400 nm), UVB (295-320 nm), UVC (254 nm) or simulated sunlight (SSL; lambda>295 nm). The resulting DNA damage spectrum for each wavelength region was then aligned with the corresponding mutational spectrum generated previously in the same genetic target. The DNA sequence specificities of CPD formation induced by UVC, UVB or SSL were very similar, i.e., in each case the overall relative proportion of this photoproduct forming at TT, TC, CT and CC sites was similar to28, similar to26, similar to16 and similar to30%, respectively. Furthermore, a clear correspondence was noted between the precise locations of CPD damage hotspots, and of 'UV signature' mutational hotspots consisting primarily of C-->T and CC-->TT transitions within pyrimidine runs. However, following UVA exposure, in strong contrast to the above situation for UVC, UVB or SSL, CPDs were generated much more frequently at TT sites than at TC, CT or CC sites (57% versus 18, 11 and 14%, respectively). This CPD deposition pattern correlates well with the strikingly high proportion of mutations recovered opposite TT dipyrimidines in UVA- irradiated CHO cells. Our results directly implicate the CPD as a major promutagenic DNA photoproduct induced specifically by UVA in rodent cells.