Kim Daein, Bhargava Ragini, Wang Shih-Chun, Lee Doohyung, Patel Riya, Oh Sungtaek, Bowman Ray W, Na Chan Hyun, O'Sullivan Roderick J, Miller Kyle M
bioRxiv. 2024 Oct 18:2024.10.18.618947. doi: 10.1101/2024.10.18.618947.
An inability to replicate the genome can cause replication stress and genome instability. Here, we develop BLOCK-ID, a proteomic method to identify and visualize proteins at stressed replication forks. This approach successfully identified novel mediators of the replication stress response, including the chromatin acetylation reader protein TRIM24. In validating TRIM24 function, we uncovered its crucial role in coordinating Alternative Lengthening of Telomeres (ALT), a cancer-specific telomere extension pathway involving replication stress. Our data reveal that TRIM24 is directed to telomeres via a p300/CBP-dependent acetylation chromatin signaling cascade, where it organizes ALT-associated PML bodies (APBs) to promote telomere DNA synthesis. Strikingly, we demonstrate that when artificially tethered at telomeres, TRIM24 can stimulate new telomere DNA synthesis in a SUMO-dependent manner, independently of p300/CBP or PML-dependent APBs. Thus, this study identifies a TRIM24 chromatin signaling pathway required for ALT telomere maintenance.
无法复制基因组会导致复制应激和基因组不稳定。在此，我们开发了BLOCK-ID，一种蛋白质组学方法，用于识别和可视化处于应激状态的复制叉处的蛋白质。该方法成功鉴定出复制应激反应的新型介质，包括染色质乙酰化读取蛋白TRIM24。在验证TRIM24的功能时，我们发现了它在协调端粒替代延长（ALT）中的关键作用，ALT是一种涉及复制应激的癌症特异性端粒延长途径。我们的数据表明，TRIM24通过p300/CBP依赖性乙酰化染色质信号级联被导向端粒，在那里它组织与ALT相关的早幼粒细胞白血病蛋白（PML）小体（APB）以促进端粒DNA合成。引人注目的是，我们证明，当TRIM24人工连接到端粒时，它可以以一种SUMO依赖性方式刺激新的端粒DNA合成，而不依赖于p300/CBP或PML依赖性APB。因此，这项研究确定了ALT端粒维持所需的TRIM24染色质信号通路。
