hMMS2 serves a redundant role in human PCNA polyubiquitination.
hMMS2 serves a redundant role in human PCNA polyubiquitination.
复制标题
DOI：
10.1186/1471-2199-9-24
复制
发表时间：
2008-02-19
影响因子：
--
通讯作者：
Gray DA
中科院分区：
文献类型：
--
作者：
Brun J;Chiu R;Lockhart K;Xiao W;Wouters BG;Gray DA
在酵母中，DNA损伤导致滑动钳形PCNA的单泛素化和多泛素化。PCNA的单泛素化由RAD18 （E3连接酶）和RAD6 （E2偶联酶）控制，而单泛素化PCNA向多泛素化底物的延伸则由RAD5和UBC13/MMS2的异源二聚体控制。每一种修饰指导DNA损伤耐受途径（DDT）的不同分支。虽然PCNA单泛素化通过TLS导致容易出错的旁路，但生化研究已经发现MMS2及其异聚体伴侣UBC13通过催化赖氨酸63连接的多泛素链（k63 - polyb）的形成来控制DNA损伤的无差错修复。最近研究表明，PCNA多泛素化在人类细胞中是保守的，并且这种修饰依赖于RAD18、UBC13和SHPRH。然而，hMMS2在这一过程中的作用并没有得到明确的解决。在这篇报告中，我们发现MMS2通过sirna介导的敲低而减少的哺乳动物细胞维持了PCNA的泛素化，而RAD18或UBC13的敲低则消除了PCNA的泛素化。此外，UEV1A （MMS2同源物）的额外敲除不会耗尽PCNA多泛素化。最后，无论是否存在mUEV1A的额外缺失，MMS2缺失的小鼠胚胎干细胞在正常动力学下继续多泛素化PCNA。我们的研究结果表明滴滴涕通路中存在高水平的冗余，并表明存在另一种hMMS2变体（hMMSv）或复合物，可以弥补其损失。
In yeast, DNA damage leads to the mono and polyubiquitination of the sliding clamp PCNA. Monoubiquitination of PCNA is controlled by RAD18 (E3 ligase) and RAD6 (E2 conjugating enzyme), while the extension of the monoubiquitinated PCNA into a polyubiquitinated substrate is governed by RAD5, and the heterodimer of UBC13/MMS2. Each modification directs a different branch of the DNA damage tolerance pathway (DDT). While PCNA monoubiquitination leads to error-prone bypass via TLS, biochemical studies have identified MMS2 along with its heteromeric partner UBC13 to govern the error-free repair of DNA lesions by catalyzing the formation of lysine 63-linked polyubiquitin chains (K63-polyUb). Recently, it was shown that PCNA polyubiquitination is conserved in human cells and that this modification is dependent on RAD18, UBC13 and SHPRH. However, the role of hMMS2 in this process was not specifically addressed. In this report we show that mammalian cells in which MMS2 was reduced by siRNA-mediated knockdown maintains PCNA polyubiquitination while a knockdown of RAD18 or UBC13 abrogates PCNA ubiquitination. Moreover, the additional knockdown of a UEV1A (MMS2 homolog) does not deplete PCNA polyubiquitination. Finally, mouse embryonic stem cells null for MMS2 with or without the additional depletion of mUEV1A continue to polyubiquitinated PCNA with normal kinetics. Our results point to a high level of redundancy in the DDT pathway and suggest the existence of another hMMS2 variant (hMMSv) or complex that can compensate for its loss.
登录
查看更多内容
影响因子：
15.3
作者：
Langerak, Petra;Nygren, Anders O. H.;Krijger, Peter H. L.;van den Berk, Paul C. M.;Jacobs, Heinz
通讯作者：
Jacobs, Heinz
影响因子：
3.8
作者：
Simpson, LJ;Sale, JE
通讯作者：
Sale, JE
影响因子：
3.8
作者：
Tissier, A;Kannouche, P;Cordonnier, A
通讯作者：
Cordonnier, A
影响因子：
4.8
作者：
Teo, H;Veprintsev, DB;Williams, RL
通讯作者：
Williams, RL
影响因子：
64.8
作者：
Stelter, P;Ulrich, HD
通讯作者：
Ulrich, HD