Institute for Immunology and School of Medicine, University of California, 3028 Hewitt Hall, Irvine, CA 92697-4120, USA.
Cell Rep. 2012 Nov 29;2(5):1220-32. doi: 10.1016/j.celrep.2012.09.029. Epub 2012 Nov 8.
By diversifying the biological effector functions of antibodies, class switch DNA recombination (CSR) plays a critical role in the maturation of the immune response. It is initiated by activation-induced cytidine deaminase (AID)-mediated deoxycytosine deamination, yielding deoxyuridine (dU), and dU glycosylation by uracil DNA glycosylase (Ung) in antibody switch (S) region DNA. Here we showed that the translesion DNA synthesis polymerase Rev1 directly interacted with Ung and targeted in an AID-dependent and Ung-independent fashion the S regions undergoing CSR. Rev1(-/-)Ung(+/+) B cells reduced Ung recruitment to S regions, DNA-dU glycosylation, and CSR. Together with an S region spectrum of mutations similar to that of Rev1(+/+)Ung(-/-) B cells, this suggests that Rev1 operates in the same pathway as Ung, as emphasized by further decreased CSR in Rev1(-/-)Msh2(-/-) B cells. Rescue of CSR in Rev1(-/-) B cells by a catalytically inactive Rev1 mutant shows that the important role of Rev1 in CSR is mediated by Rev1's scaffolding function, not its enzymatic function.
通过使抗体的生物效应功能多样化，类别转换 DNA 重组 (CSR) 在免疫反应的成熟过程中发挥着关键作用。它是由激活诱导的胞嘧啶脱氨酶 (AID) 介导的脱氧胞嘧啶脱氨作用引发的，在抗体开关 (S) 区 DNA 中产生脱氧尿嘧啶 (dU)，并由尿嘧啶 DNA 糖基化酶 (Ung) 进行 dU 糖基化。在这里，我们表明跨损伤 DNA 合成聚合酶 Rev1 直接与 Ung 相互作用，并以 AID 依赖性和 Ung 非依赖性的方式靶向正在发生 CSR 的 S 区。Rev1(-/-)Ung(+/+)B 细胞减少了 Ung 向 S 区的募集、DNA-dU 糖基化和 CSR。与 Rev1(+/+)Ung(-/-)B 细胞相似的 S 区突变谱一起，这表明 Rev1 与 Ung 处于相同的途径，正如 Rev1(-/-)Msh2(-/-)B 细胞中 CSR 进一步减少所强调的那样。Rev1(-/-)B 细胞中 CSR 的挽救通过催化失活的 Rev1 突变体表明 Rev1 在 CSR 中的重要作用是通过 Rev1 的支架功能介导的，而不是其酶功能。
