UBE2V2 (MMS2) is not required for effective immunoglobulin gene conversion or DNA damage tolerance in DT40
UBE2V2 (MMS2) is not required for effective immunoglobulin gene conversion or DNA damage tolerance in DT40
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DOI：
10.1016/j.dnarep.2004.12.002
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发表时间：
2005-04-04
期刊：
影响因子：
3.8
通讯作者：
Sale, JE
中科院分区：
文献类型：
--
作者：
Simpson, LJ;Sale, JE
RAD 6/RAD 18异源二聚体通过DNA滑动钳（PCNA）的单倍半胱氨酸化促进跨损伤合成。In S.在酿酒酵母中，第二个复合物UBC 13/MMS 2/RAD 5可以用非典型的赖氨酸63连接链延伸这个单一的遍在蛋白。这个多聚泛素化步骤是一个无错误的旁路模式所必需的，可能是由停滞的复制复合体进行的模板转换。MMS 2的人类同源物UBE 2 V2在这样的过程中的作用的证据已经从在人类成纤维细胞中转录物的反义敲低后紫外光诱导的基因转化的废除中推断出来。为了询问是否有类似的机制有助于无碱基位点诱导的免疫球蛋白基因转换，并确定UBE 2 V2在脊椎动物DNA损伤反应中的作用，我们创建了鸡细胞系DT 40的UBE 2 V2突变体。与芽殖酵母mms 2不同，ube 2 v2 DT 40对DNA损伤不表现出显著的超敏反应，也不表现出在脊椎动物rad 18突变体中观察到的升高的姐妹染色单体交换，这表明UBE 2 V2在依赖于rad 18的DNA损伤耐受性中起次要或多余的作用。此外，ube 2 v2和rad 18 DT 40都显示出或多或少的正常水平的免疫球蛋白基因转换，尽管RAD 18在DNA损伤诱导的跨损伤合成中发挥重要作用，但rad 18 DT 40与rev 1 DT 40不同，在非模板化免疫球蛋白基因突变中没有显示出缺陷。总之，这些数据表明，通过PCNA泛素化的信号转导是不需要免疫球蛋白多样化的DT 40。(c)2004 Elsevier B. V.保留所有权利。
The RAD6/RAD18 heterodimer promotes translesion synthesis via the monoubiquitination of the DNA sliding clamp, PCNA. In S. cerevisiae, a second complex, UBC13/MMS2/RAD5, can extend this single ubiquitin with a non-canonical lysine 63-linked chain. This polyubiquitination step is required for an error-free mode of bypass, possibly template switching by the stalled replication complex. Evidence of a role for the human homologue of MMS2, UBE2V2, in such a process has been inferred from the abrogation of ultraviolet light-induced gene conversion following antisense knockdown of the transcript in human fibroblasts. To ask whether a similar mechanism contributes to abasic site-induced immunoglobulin gene conversion, and to ascertain the role of UBE2V2 in the vertebrate DNA damage response we created a ube2v2 mutant of the chicken cell line DT40. Unlike budding yeast mms2, ube2v2 DT40 does not exhibit significant hypersensitivity to DNA damage, nor the elevated sister chromatid exchange seen in vertebrate rad18 mutants suggesting that UBE2V2 plays a minor or redundant role in RAD18 dependent DNA damage tolerance. In addition, both ube2v2 and rad18 DT40 display more or less normal levels of immunoglobulin gene conversion and, despite the important role played by RAD18 in DNA damage induced translesion synthesis, rad18 DT40, unlike rev1 DT40, does not show a defect in non-templated immunoglobulin gene mutation. Together these data suggest that signalling through PCNA ubiquitination is not required for immunoglobulin diversification in DT40. (c) 2004 Elsevier B.V. All rights reserved.