Replication stress and mitotic dysfunction in cells expressing simian virus 40 large T antigen.
Replication stress and mitotic dysfunction in cells expressing simian virus 40 large T antigen.
复制标题
表达猿病毒 40 大 T 抗原的细胞中的复制应激和有丝分裂功能障碍。
DOI：
10.1128/jvi.02224-13
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发表时间：
2013
影响因子：
5.4
通讯作者：
Gjoerup,OleV
中科院分区：
文献类型：
--
作者：
Hu,Liang;Filippakis,Harilaos;Huang,Haomin;Yen,TimothyJ;Gjoerup,OleV
我们以前证明了猴病毒40(SV40)大T抗原(LT)与Bub1激酶结合，Bub1激酶是纺锤体检查点和染色体分离的关键调节因子。BUB1突变或表达模式改变与染色体错误分离有关，被认为是一些人类癌症的驱动力。在这里，我们报告LT依赖于Bub1结合，导致微核、染色质滞后和后期桥，这些都是染色体不稳定(CIN)和Bub1不足的特征。使用时间推移显微镜，我们证明了LT在中期到后期的转变中施加了一个依赖于Bub1结合的延迟。动粒纤维显示，LT通过Bub1结合，导致动粒(KT)-微管(MT)连接异常，动粒间距离缩短，与张力缺乏一致。以前，我们已经证明LT也通过Bub1结合来诱导DNA损伤反应(DDR)。利用可诱导的LT细胞系，我们发现在后期桥和微核出现之前，观察到了激活的DDR。此外，在血清饥饿细胞中的LT诱导显示，γ-H_2AX在尚未进入有丝分裂的细胞中积累。因此，DDR激活可以独立于染色体分离缺陷而发生。复制应激途径可能起作用，因为观察到复制应激的特征，而外源核苷的补充减弱了复制应激的影响。我们的观察使我们能够提出一个模型来解释和整合LT诱导的基因组不稳定的不同表现。
We previously demonstrated that simian virus 40 (SV40) large T antigen (LT) binds to the Bub1 kinase, a key regulator of the spindle checkpoint and chromosome segregation. Bub1 mutations or altered expression patterns are linked to chromosome missegregation and are considered to be a driving force in some human cancers. Here we report that LT, dependent on Bub1 binding, causes micronuclei, lagging chromatin, and anaphase bridges, which are hallmarks of chromosomal instability (CIN) and Bub1 insufficiency. Using time-lapse microscopy, we demonstrate that LT imposes a Bub1 binding-dependent delay in the metaphase-to-anaphase transition. Kinetochore fibers reveal that LT, via Bub1 binding, causes aberrant kinetochore (KT)-microtubule (MT) attachments and a shortened interkinetochore distance, consistent with a lack of tension. Previously, we showed that LT also induces the DNA damage response (DDR) via Bub1 binding. Using inducible LT cell lines, we show that an activated DDR was observed before the appearance of anaphase bridges and micronuclei. Furthermore, LT induction in serum-starved cells demonstrated γ-H2AX accumulation in cells that had not yet entered mitosis. Thus, DDR activation can occur independently of chromosome segregation defects. Replication stress pathways may be responsible, because signatures of replication stress were observed, which were attenuated by exogenous supplementation with nucleosides. Our observations allow us to propose a model that explains and integrates the diverse manifestations of genomic instability induced by LT.