JAK2V617F promotes replication fork stalling with disease-restricted impairment of the intra-S checkpoint response
JAK2V617F promotes replication fork stalling with disease-restricted impairment of the intra-S checkpoint response
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DOI：
10.1073/pnas.1401873111
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发表时间：
2014-10-21
影响因子：
11.1
通讯作者：
Green, Anthony R.
中科院分区：
文献类型：
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作者：
Chen, Edwin;Ahn, Jong Sook;Green, Anthony R.
癌症是遗传损伤积累的结果，但驱动突变的细胞后果尚不清楚，特别是在恶性肿瘤的早期阶段。JAK2非受体酪氨酸激酶(JAK2V617F)的V617F突变在大多数骨髓增生性肿瘤(MPN)患者中是一种早期的躯体事件，对这些慢性髓系恶性肿瘤的研究为理解早期肿瘤的发生提供了一种实验上容易处理的方法。外源JAK2V617F的引入抑制了复制分叉的进程，并与S内部检查点的激活有关，这两种影响都由磷脂酰肌醇3-激酶(PI3K)信号介导。对MPN患者克隆性来源的JAK2V617F阳性红细胞的分析也表明，复制分叉进展受损，并伴有含有复制蛋白A(RPA)的病灶水平增加。然而，真性红细胞增多症(PV)患者的红细胞内S检查点反应受损，而原发性血小板增多症(ET)患者的红细胞内S检查点反应不受影响。此外，与类似处理的ET红细胞相比，抑制PV红细胞中的p53导致更多的伽马-H_2AX(Gamma-H_2AX)标记的双链断裂，这表明PV中存在的S内部检查点功能缺陷在p53信号减弱的背景下增加了DNA损伤。这些结果证实了癌基因诱导的MPN患者原代细胞复制分叉进程的障碍，揭示了意外的疾病限制性的S检查点激活的差异，并对恶性肿瘤的克隆进化具有潜在的意义。
Cancers result from the accumulation of genetic lesions, but the cellular consequences of driver mutations remain unclear, especially during the earliest stages of malignancy. The V617F mutation in the JAK2 non-receptor tyrosine kinase (JAK2V617F) is present as an early somatic event in most patients with myeloproliferative neoplasms (MPNs), and the study of these chronic myeloid malignancies provides an experimentally tractable approach to understanding early tumorigenesis. Introduction of exogenous JAK2V617F impairs replication fork progression and is associated with activation of the intra-S checkpoint, with both effects mediated by phosphatidylinositide 3-kinase (PI3K) signaling. Analysis of clonally derived JAK2V617F-positive erythroblasts from MPN patients also demonstrated impaired replication fork progression accompanied by increased levels of replication protein A (RPA)-containing foci. However, the associated intra-S checkpoint response was impaired in erythroblasts from polycythemia vera (PV) patients, but not in those from essential thrombocythemia (ET) patients. Moreover, inhibition of p53 in PV erythroblasts resulted in more gamma-H2Ax (gamma-H2Ax)-marked double-stranded breaks compared with in like-treated ET erythroblasts, suggesting the defective intra-S checkpoint function seen in PV increases DNA damage in the context of attenuated p53 signaling. These results demonstrate oncogene-induced impairment of replication fork progression in primary cells from MPN patients, reveal unexpected disease-restricted differences in activation of the intra-S checkpoint, and have potential implications for the clonal evolution of malignancies.