这项研究调查了异构体转换如何影响细胞对电离辐射 (IR) 的反应，这是一个尚未研究的领域，尽管它与癌症治疗中的放射治疗相关。我们的目的是确定 IR 暴露后转录同工型表达的变化以及介导这些变化的蛋白质，重点关注它们调节放射敏感性的潜力。使用 RNA 测序，我们分析了来自 10 名健康个体在三个时间点的 B 细胞系，应用 MISO 算法来量化选择性剪接。我们检查了 IR 响应异构体序列中的 RBP 基序，并通过 RNA 免疫沉淀验证了富含丝氨酸/精氨酸的剪接因子 1 (SRSF1) 作为主要介质。我们通过在体外敲低 SRSF1 并分析公开的癌症患者数据，进一步研究了 SRSF1 对放射敏感性的影响。我们鉴定了约 1,900 种放射响应性可变剪接亚型。许多亚型存在差异表达，但总体基因表达没有变化。这些转录本中有超过三分之一经历了外显子跳跃，而其他转录本则使用了近端的最后一个外显子。这些 IR 响应亚型往往是较短的转录本，缺少防止细胞凋亡和促进细胞分裂的重要结构域，但保留了 DNA 修复所需的结构域。我们综合计算、遗传和分子分析确定原癌基因富含丝氨酸/精氨酸剪接因子 1 (SRSF1) 是这些辐射诱导的异构体转换事件的介体，从而促进细胞凋亡。暴露于 DNA 双链断裂诱导剂后，SRSF1 表达下降。 SRSF1 的减少增加了体外和癌症患者的放射敏感性。我们确定了异构体转换在细胞对 IR 反应中的关键作用，并提出 SRSF1 作为评估放射治疗效果的有前景的生物标志物。版权所有 © 2024。由 Elsevier Inc. 出版。

This study investigates how isoform switching affects the cellular response to ionizing radiation (IR), an understudied area, despite its relevance to radiotherapy in cancer treatment. We aimed to identify changes in transcript isoform expression post-IR exposure and the proteins mediating these changes, with a focus on their potential to modulate radiosensitivity.Using RNA sequencing, we analyzed the B-cell lines derived from 10 healthy individuals at three timepoints, applying the MISO algorithm to quantify alternative splicing. We examined RBP motifs within the sequences of IR-responsive isoforms and validated the Serine/Arginine-Rich Splicing Factor 1 (SRSF1) as a predominant mediator through RNA-immunoprecipitation. We further investigated the effects of SRSF1 on radiosensitivity by knocking it down in vitro and by analyzing publicly-available cancer patient data.We identified ∼1,900 radiation-responsive alternatively-spliced isoforms. Many isoforms were differentially expressed without changes in their overall gene expression. Over a third of these transcripts underwent exon skipping, while others used proximal last exons. These IR-responsive isoforms tended to be shorter transcripts missing vital domains for preventing apoptosis and promoting cell division, but retaining those necessary for DNA repair. Our combined computational, genetic and molecular analyses identified the proto-oncogene Serine/Arginine-Rich Splicing Factor 1 (SRSF1) as a mediator of these radiation-induced isoform-switching events that promote apoptosis. After exposure to DNA double-strand break-inducing agents, SRSF1 expression decreased. A reduction in SRSF1 increased radiosensitivity in vitro and among cancer patients.We establish a pivotal role for isoform switching in the cellular response to IR and propose SRSF1 as a promising biomarker for assessing radiotherapy effectiveness.Copyright © 2024. Published by Elsevier Inc.