WRN loss induces switching of telomerase-independent mechanisms of telomere elongation.
WRN loss induces switching of telomerase-independent mechanisms of telomere elongation.
复制标题
DOI：
10.1371/journal.pone.0093991
复制
发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Groden J
中科院分区：
文献类型：
--
作者：
Gocha AR;Acharya S;Groden J
端粒的维持可以在端粒酶存在或不存在的情况下发生，称为端粒的交替延长（ALT）。ALT使用基于重组的过程和在同源重组中起作用的DNA修复蛋白添加端粒重复序列。我们以前的工作报告，RecQ样BLM解旋酶是ALT所需的，它在体外解旋端粒底物。WRN也是一种RecQ样解旋酶，与BLM共享许多生化功能。WRN与BLM相互作用，解旋端粒底物，并共定位于ALT相关的PML小体（APBs），这表明它也可能是ALT过程所需的。使用长期siRNA敲低WRN在三个ALT细胞系，我们表明，一些，但不是所有的细胞系需要WRN端粒维护。VA-13细胞需要WRN来防止端粒丢失和APB的形成; Saos-2细胞不需要。第三种ALT细胞系U-2 OS需要WRN来形成APB，然而WRN缺失导致p53介导的细胞凋亡。在WRN和p53不存在的情况下，U-2 OS细胞经历端粒损失，达到中等数量的群体倍增（50-70），在该点，即使WRN持续损失，它们也保持端粒长度。WRN和肿瘤抑制因子BRCA 1共定位于VA-13和U-2 OS中的APB，但不在Saos-2细胞中。U-2 OS中WRN的丢失与APB中BRCA 1的丢失有关。在这三种ALT细胞系中，虽然WRN的缺失显著增加端粒姐妹染色单体交换（T-SCE），但BRCA 1和WRN的缺失并不显著改变T-SCE。这项工作表明，ALT细胞系使用不同的端粒不依赖的维护机制，这些机制不需要WRN解旋酶，并且一些细胞可以从一种机制切换到另一种机制，从而允许在没有WRN的情况下端粒延长。我们的数据表明，BRCA 1定位可能定义这些机制。
Telomere maintenance can occur in the presence of telomerase or in its absence, termed alternative lengthening of telomeres (ALT). ALT adds telomere repeats using recombination-based processes and DNA repair proteins that function in homologous recombination. Our previous work reported that the RecQ-like BLM helicase is required for ALT and that it unwinds telomeric substrates in vitro. WRN is also a RecQ-like helicase that shares many biochemical functions with BLM. WRN interacts with BLM, unwinds telomeric substrates, and co-localizes to ALT-associated PML bodies (APBs), suggesting that it may also be required for ALT processes. Using long-term siRNA knockdown of WRN in three ALT cell lines, we show that some, but not all, cell lines require WRN for telomere maintenance. VA-13 cells require WRN to prevent telomere loss and for the formation of APBs; Saos-2 cells do not. A third ALT cell line, U-2 OS, requires WRN for APB formation, however WRN loss results in p53-mediated apoptosis. In the absence of WRN and p53, U-2 OS cells undergo telomere loss for an intermediate number of population doublings (50–70), at which point they maintain telomere length even with the continued loss of WRN. WRN and the tumor suppressor BRCA1 co-localize to APBs in VA-13 and U-2 OS, but not in Saos-2 cells. WRN loss in U-2 OS is associated with a loss of BRCA1 from APBs. While the loss of WRN significantly increases telomere sister chromatid exchanges (T-SCE) in these three ALT cell lines, loss of both BRCA1 and WRN does not significantly alter T-SCE. This work demonstrates that ALT cell lines use different telomerase-independent maintenance mechanisms that variably require the WRN helicase and that some cells can switch from one mechanism to another that permits telomere elongation in the absence of WRN. Our data suggest that BRCA1 localization may define these mechanisms.
登录
查看更多内容
影响因子：
64.5
作者：
Hu J;Hwang SS;Liesa M;Gan B;Sahin E;Jaskelioff M;Ding Z;Ying H;Boutin AT;Zhang H;Johnson S;Ivanova E;Kost-Alimova M;Protopopov A;Wang YA;Shirihai OS;Chin L;DePinho RA
通讯作者：
DePinho RA
影响因子：
14.9
作者：
Cawthon RM
通讯作者：
Cawthon RM
DOI：
10.1073/pnas.1006338107
发表时间：
2010-09-07
影响因子：
11.1
作者：
Hagelstrom, R. Tanner;Blagoev, Krastan B.;Bailey, Susan M.
通讯作者：
Bailey, Susan M.
影响因子：
3.5
作者：
Lillard-Wetherell, K;Machwe, A;Groden, J
通讯作者：
Groden, J
影响因子：
4.8
作者：
Jiang, KC;Pereira, E;Sanchez, Y
通讯作者：
Sanchez, Y