A positive feedback loop of SIRT1 and miR17HG promotes the repair of DNA double-stranded breaks
A positive feedback loop of SIRT1 and miR17HG promotes the repair of DNA double-stranded breaks
复制标题
SIRT1 和 miR17HG 的正反馈环促进 DNA 双链断裂的修复
DOI：
10.1080/15384101.2019.1641388
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发表时间：
2019-07-16
期刊：
影响因子：
4.3
通讯作者：
Xu, Shun
中科院分区：
文献类型：
--
作者：
Xie, Luoyijun;Huang, Ruxiao;Xu, Shun
摘要长链非编码RNA（lncRNA）是多水平基因表达的重要调控因子，参与多种生理和病理过程。Sirtuin 1（SIRT 1）是一种通过底物的脱乙酰化作用参与DNA损伤修复等多种生物学过程的蛋白质。然而，SIRT 1和lncRNA之间的调控关系，以及lncRNA对SIRT 1介导的功能的影响仍远未阐明。我们在此发现，lncRNA miR 17 HG在SIRT 1缺陷细胞中显著下调，并且在SIRT 1异位表达后显著上调。随后，双荧光素酶报告基因（DLR）的结果显示，SIRT 1显著增强了miR-17-92簇的启动子活性。此外，我们特异性地敲除了先前证明的miR-17-92簇的转录因子C-Myc，其是SIRT 1的验证底物。正如预期的那样，沉默C-Myc后miR 17 HG和miR-17-92的表达明显下调;沉默C-Myc显著逆转了SIRT 1对miR 17 HG表达的影响，表明SIRT 1通过稳定C-Myc赋予细胞增加的miR 17 HG表达。miR 17 HG的沉默显著抑制了DNA双链断裂的修复，而miR 17 HG的增强表达促进了DNA双链断裂的修复。令人着迷的是，miR 17 HG的过表达明显增强了SIRT 1的脱乙酰化活性，而miR 17 HG的沉默则降低了脱乙酰化活性。此外，RIP的结果揭示了miR 17 HG和SIRT 1之间的物理相互作用。综上所述，我们提出的证据表明，miR 17 HG和SIRT 1可能形成了一个正反馈回路，这对DSB修复起着至关重要的作用。
ABSTRACT Long noncoding RNAs (lncRNAs) have emerged as critical regulators for gene expression in multiple levels and thus are involved in various physiological and pathological processes. Sirtuin 1 (SIRT1) has been established to exert key roles in the diverse biological process through deacetylation of substrates, including DNA damage repair. Nevertheless, the regulatory relationship between SIRT1 and lncRNAs, and the effect of lncRNA on SIRT1-mediated functions were still far to be elucidated. We herein uncovered that lncRNA miR17HG was notably down-regulated in SIRT1-deficient cells, and significantly up-regulated after ectopic expression of SIRT1. Subsequently, the results of dual luciferase reporter (DLR) showed that SIRT1 dramatically enhanced the promoter activity of the miR-17-92 cluster. Furthermore, we specifically knocked down the previous demonstrated transcription factor for the miR-17-92 cluster, C-Myc, which was the validated substrate of SIRT1. As expected, miR17HG and miR-17-92 miRNAs were evidently down-regulated after silencing of C-Myc; and silencing of C-Myc significantly reversed the effect of SIRT1 on miR17HG expression, suggesting that SIRT1 endowed cells with elevated miR17HG expression through stabilization of C-Myc. What is more, silencing of miR17HG significantly inhibited the repair of DNA DSBs, while enforced expression of miR17HG promoted DSBs repair. Fascinatingly, overexpression of miR17HG evidently enhanced the deacetylation activity of SIRT1, while silencing of miR17HG conferred diminished deacetylation activity. In addition, the results of RIP unraveled the physical interaction between miR17HG and SIRT1. Taken together, we presented evidences that miR17HG and SIRT1 probably formed a positive feedback loop, which exerted a crucial effect on DSBs repair.