Kim Daein, Bhargava Ragini, Wang Shih-Chun, Tseng Wei-Che, Lee Doohyung, Patel Riya, Oh Sungtaek, Bowman Ray W, Smith Baylee A, Kim Minkyu, Na Chan Hyun, O'Sullivan Roderick J, Miller Kyle M
Department of Molecular Biosciences, The University of Texas at Austin, Austin, TX 78712, USA.
Department of Pharmacology and Chemical Biology, UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA 15232, USA.
Mol Cell. 2025 Jul 17;85(14):2636-2653.e8. doi: 10.1016/j.molcel.2025.06.009. Epub 2025 Jul 3.
An inability to replicate the genome can cause replication stress and genome instability. Here, we develop biotinylation of lac operator (LacO) array replication stress protein network identification (BLOCK-ID) in human cancer cells, a proteomic method to identify and visualize proteins at stressed replication forks. This approach identified mediators of the replication stress response, including the chromatin acetylation reader protein tripartite motif containing 24 (TRIM24). We uncovered a crucial role for TRIM24 in coordinating alternative lengthening of telomeres (ALT), a replication stress-directed telomere extension mechanism. Our data reveal that TRIM24 is recruited to telomeres via a p300/CREB binding protein (CBP)-dependent acetylation chromatin signaling cascade to organize the assembly of ALT-associated promyelocytic leukemia (PML) bodies (APBs) and promote de novo telomere DNA synthesis. Tethering of TRIM24 at telomeres was sufficient to stimulate de novo telomere DNA synthesis in a small ubiquitin-like modifier (SUMO)-dependent but p300/CBP- and PML-independent manner. Collectively, these findings uncover an indispensable epigenetic signaling pathway involving TRIM24 and p300/CBP that mediates ALT-telomere maintenance.
基因组无法复制会导致复制应激和基因组不稳定。在此，我们开发了一种在人类癌细胞中进行乳糖操纵子（LacO）阵列复制应激蛋白网络识别的生物素化方法（BLOCK-ID），这是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。该方法鉴定出了复制应激反应的介质，包括染色质乙酰化读取蛋白含三联基序24（TRIM24）。我们发现TRIM24在协调端粒的替代延长（ALT）中起关键作用，ALT是一种由复制应激导向的端粒延长机制。我们的数据表明，TRIM24通过p300/CREB结合蛋白（CBP）依赖性的乙酰化染色质信号级联被招募到端粒，以组织ALT相关早幼粒细胞白血病（PML）小体（APB）的组装并促进端粒DNA的从头合成。将TRIM24拴系在端粒上足以以一种小泛素样修饰物（SUMO）依赖性但p300/CBP和PML非依赖性的方式刺激端粒DNA的从头合成。总的来说，这些发现揭示了一条涉及TRIM24和p300/CBP的不可或缺的表观遗传信号通路，该通路介导ALT端粒的维持。
