Replication licensing promotes cyclin D1 expression and G1 progression in untransformed human cells.
Replication licensing promotes cyclin D1 expression and G1 progression in untransformed human cells.
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DOI：
10.4161/cc.8.1.7528
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发表时间：
2009-01-01
期刊：
影响因子：
--
通讯作者：
Vaziri C
中科院分区：
文献类型：
--
作者：
Liu P;Slater DM;Lenburg M;Nevis K;Cook JG;Vaziri C
DNA 复制缺陷与恶性肿瘤的早期因果事件有关。然而，DNA 复制许可受损对非恶性人类细胞的细胞周期进程的直接影响尚不清楚。因此，我们使用未转化的人真皮成纤维细胞 (HDF) 的同步培养物研究了 Mcm7 消融的急性影响。 Mcm7 消除引起与 CDK4 和 CDK2 激活受损以及 Rb 磷酸化减少相关的 G1 延迟。 Mcm7 消除细胞的细胞周期延迟与 DNA 损伤反应无关。然而，在 Mcm7 耗尽的细胞中，细胞周期蛋白 D1 mRNA 的水平明显降低，RNA 聚合酶 II 与 CYCD1 启动子的结合也降低。与 Mcm7 缺陷类似，Mcm2 或 Cdc6 缺失会导致细胞周期蛋白 D 表达受损。静止细胞中 Cdc6 的异位过度表达促进了细胞周期蛋白 D1 表达、CDK4 激活和 G1 期进展。因此，在 G1 期及时有效地表达 cyclin D1 需要复制许可。细胞周期蛋白 D1 表达的重建不足以纠正 Mcm7 耗尽细胞的 G1 延迟，表明 G1 期间的其他细胞周期事件依赖于复制许可。然而，HPV-E7 癌蛋白的异位表达以及由此产生的对细胞周期蛋白 D1-Rb 信号传导需求的绕过使得 Mcm7 耗尽的细胞进入 S 期。 HPV-E7 诱导 Mcm7 耗尽的细胞进入 S 期，导致 DNA 损伤反应，这是恶性肿瘤前期的标志。综上所述，我们的结果表明存在一个“复制许可限制点”，它将预 RC 组装与正常细胞中的 G1 进程结合起来，以最大限度地减少复制压力、DNA 损伤和肿瘤发生。
Defects in DNA replication are implicated as early and causal events in malignancy. However, the immediate effects of impaired DNA replication licensing on cell cycle progression of non-malignant human cells are unknown. Therefore, we have investigated the acute effects of Mcm7 ablation using synchronized cultures of untransformed Human Dermal Fibroblasts (HDF). Mcm7 ablation elicited a G1 delay associated with impaired activation of CDK4 and CDK2 and reduced Rb phosphorylation. The cell cycle delay of Mcm7-ablated cells was not associated with a DNA damage response. However, levels of cyclin D1 mRNA were specifically reduced and binding of RNA Polymerase II to the CYCD1 promoter was decreased in Mcm7-depleted cells. Similar to Mcm7-deficiency, Mcm2- or Cdc6-depletion led to impaired cyclin D expression. Ectopic overexpression of Cdc6 in quiescent cells promoted cyclin D1 expression, CDK4 activation and G1 progression. Therefore timely and efficient expression of cyclin D1 during G1 phase requires replication licensing. Reconstitution of cyclin D1 expression was insufficient to correct the G1 delay of Mcm7-depleted cells, indicating that additional cell cycle events during G1 are dependent on replication licensing. However, ectopic expression of the HPV-E7 oncoprotein, and the resulting bypass of the requirement for cyclin D1-Rb signaling enabled Mcm7-depleted cells to enter S-phase. HPV-E7-induced S-phase entry of Mcm7-depleted cells led to a DNA damage response, a hallmark of pre-malignancy. Taken together, our results suggest the existence of a ‘replication licensing restriction point’ that couples pre-RC assembly with G1 progression in normal cells to minimize replication stress, DNA damage and tumorigenesis.
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DOI：
10.1083/jcb.152.6.1267
发表时间：
2001-03-19
期刊：
The Journal of cell biology
影响因子：
--
作者：
Furstenthal L;Kaiser BK;Swanson C;Jackson PK
通讯作者：
Jackson PK
DOI：
10.1073/pnas.061487598
发表时间：
2001-03-13
影响因子：
11.1
作者：
DaFonseca, CJ;Shu, F;Zhang, JJ
通讯作者：
Zhang, JJ
影响因子：
4.8
作者：
Fitch, MJ;Donato, JJ;Tye, BK
通讯作者：
Tye, BK
影响因子：
21.3
作者：
Gambus, A;Jones, RC;Labib, K
通讯作者：
Labib, K
影响因子：
10.5
作者：
Laribee, R. Nicholas;Fuchs, Stephen M.;Strahl, Brian D.
通讯作者：
Strahl, Brian D.