The deubiquitinating enzyme USP37 is known to contribute to timely onset of S phase and progression of mitosis. However, it is not clear if USP37 is required beyond S-phase entry despite expression and activity of USP37 peaking within S phase. We have utilized flow cytometry and microscopy to analyze populations of replicating cells labeled with thymidine analogs and monitored mitotic entry in synchronized cells to determine that USP37-depleted cells exhibited altered S-phase kinetics. Further analysis revealed that cells depleted of USP37 harbored increased levels of the replication stress and DNA damage markers γH2AX and 53BP1 in response to perturbed replication. Depletion of USP37 also reduced cellular proliferation and led to increased sensitivity to agents that induce replication stress. Underlying the increased sensitivity, we found that the checkpoint kinase 1 is destabilized in the absence of USP37, attenuating its function. We further demonstrated that USP37 deubiquitinates checkpoint kinase 1, promoting its stability. Together, our results establish that USP37 is required beyond S-phase entry to promote the efficiency and fidelity of replication. These data further define the role of USP37 in the regulation of cell proliferation and contribute to an evolving understanding of USP37 as a multifaceted regulator of genome stability.

中文翻译：

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去泛素化酶 USP37 增强 CHK1 活性以促进细胞对复制应激的反应。

已知去泛素化酶 USP37 有助于 S 期的及时发生和有丝分裂的进展。然而，尽管 USP37 的表达和活性在 S 期达到峰值，但尚不清楚进入 S 期后是否需要 USP37。我们利用流式细胞术和显微镜来分析用胸苷类似物标记的复制细胞群，并监测同步细胞中的有丝分裂进入，以确定 USP37 耗尽的细胞表现出改变的 S 期动力学。进一步的分析表明，USP37 耗尽的细胞具有更高水平的复制应激和 DNA 损伤标记物 γH2AX 和 53BP1，以响应复制扰动。USP37 的消耗也减少了细胞增殖并导致对诱导复制应激的药物的敏感性增加。在敏感性增加的基础上，我们发现检查点激酶 1 在没有 USP37 的情况下不稳定，减弱了它的功能。我们进一步证明 USP37 去泛素化检查点激酶 1，促进其稳定性。总之，我们的结果表明，进入 S 期后需要 USP37 来提高复制的效率和保真度。这些数据进一步确定了 USP37 在调节细胞增殖中的作用，并有助于进一步理解 USP37 作为基因组稳定性的多方面调节器。