Gabriel M Cohn, Colin J Daniel, Jennifer R Eng, Xiao-Xin Sun, Carl Pelz, Koei Chin, Alexander Smith, Charles D Lopez, Jonathan R Brody, Mu-Shui Dai, Rosalie C Sears
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引用次数: 0
摘要
基因组不稳定性是癌症的一大特征,它可导致致癌突变,从而增强肿瘤的侵袭性和耐药性。MYC是一种主转录因子,几乎在所有人类肿瘤中都会发生失调,它在诱导复制压力和相关DNA损伤的同时,也会增加DNA修复因子的表达,并介导对DNA损伤疗法的耐受性。新的证据表明,MYC 在保持活跃转录位点的基因组完整性和保护压力下停滞的复制叉方面发挥着非转录作用。了解 MYC 的基因毒性和基因保护功能是如何分化的,可能会为 MYC 驱动的癌症揭示新的治疗策略。在这里,我们通过 MYC 与 DNA 断裂的直接关联,确定了它在 DNA 损伤应答(DDR)中的非经典作用。我们发现,丝氨酸 62(pS62-MYC)处的磷酸化对 MYC 有效招募到损伤位点、与修复因子 BRCA1 和 RAD51 相互作用以及有效修复 DNA 以支持细胞在压力下存活至关重要。在复制应激过程中与 MYC-BioID2 的质谱分析显示,MYC 的相互作用组发生了变化,在保持 DDR 关联的同时失去了转录调节因子。这些发现使 pS62-MYC 成为基因组稳定性的关键调节因子和癌症的潜在治疗靶点。
MYC Serine 62 phosphorylation promotes its binding to DNA double strand breaks to facilitate repair and cell survival under genotoxic stress.
Genomic instability is a hallmark of cancer, driving oncogenic mutations that enhance tumor aggressiveness and drug resistance. MYC, a master transcription factor that is deregulated in nearly all human tumors, paradoxically induces replication stress and associated DNA damage while also increasing expression of DNA repair factors and mediating resistance to DNA-damaging therapies. Emerging evidence supports a non-transcriptional role for MYC in preserving genomic integrity at sites of active transcription and protecting stalled replication forks under stress. Understanding how MYC's genotoxic and genoprotective functions diverge may reveal new therapeutic strategies for MYC-driven cancers. Here, we identify a non-canonical role of MYC in DNA damage response (DDR) through its direct association with DNA breaks. We show that phosphorylation at serine 62 (pS62-MYC) is crucial for the efficient recruitment of MYC to damage sites, its interaction with repair factors BRCA1 and RAD51, and effective DNA repair to support cell survival under stress. Mass spectrometry analysis with MYC-BioID2 during replication stress reveals a shift in MYC's interactome, maintaining DDR associations while losing transcriptional regulators. These findings establish pS62-MYC as a key regulator of genomic stability and a potential therapeutic target in cancers.