Stagni Venturina, Orecchia Silvia, Mignini Luca, Beji Sara, Antonioni Ambra, Caggiano Cinzia, Barilà Daniela, Bielli Pamela, Sette Claudio
Institute of Molecular Biology and Pathology, National Research Council (CNR), 00185 Rome, Italy.
IRCCS Fondazione Santa Lucia, 00143 Rome, Italy.
Cancers (Basel). 2022 Aug 9;14(16):3847. doi: 10.3390/cancers14163847.
Cancer cells frequently exhibit dysregulation of the DNA damage response (DDR), genomic instability, and altered RNA metabolism. Recent genome-wide studies have strongly suggested an interaction between the pathways involved in the cellular response to DDR and in the regulation of RNA metabolism, but the molecular mechanism(s) involved in this crosstalk are largely unknown. Herein, we found that activation of the DDR kinase ATM promotes its interaction with Sam68, leading to phosphorylation of this multifunctional RNA binding protein (RBP) on three residues: threonine 61, serine 388 and serine 390. Moreover, we demonstrate that ATM-dependent phosphorylation of threonine 61 promotes the function of Sam68 in the DDR pathway and enhances its RNA processing activity. Importantly, ATM-mediated phosphorylation of Sam68 in prostate cancer cells modulates alternative polyadenylation of transcripts that are targets of Sam68, supporting the notion that the ATM-Sam68 axis exerts a multifaceted role in the response to DNA damage. Thus, our work validates Sam68 as an ATM kinase substrate and uncovers an unexpected bidirectional interplay between ATM and Sam68, which couples the DDR pathway to modulation of RNA metabolism in response to genotoxic stress.
癌细胞经常表现出DNA损伤反应（DDR）失调、基因组不稳定以及RNA代谢改变。最近的全基因组研究强烈表明，细胞对DDR的反应途径与RNA代谢调控途径之间存在相互作用，但这种相互作用所涉及的分子机制在很大程度上尚不清楚。在此，我们发现DDR激酶ATM的激活促进了它与Sam68的相互作用，导致这种多功能RNA结合蛋白（RBP）在三个残基上磷酸化：苏氨酸61、丝氨酸388和丝氨酸390。此外，我们证明苏氨酸61的ATM依赖性磷酸化促进了Sam68在DDR途径中的功能，并增强了其RNA加工活性。重要的是，前列腺癌细胞中ATM介导的Sam68磷酸化调节了作为Sam68靶标的转录本的可变聚腺苷酸化，支持了ATM-Sam68轴在DNA损伤反应中发挥多方面作用的观点。因此，我们的工作证实了Sam68是一种ATM激酶底物，并揭示了ATM与Sam68之间意想不到的双向相互作用，这种相互作用将DDR途径与响应基因毒性应激的RNA代谢调节联系起来。
