RNA激活(RNAa)

RNA激活(RNA activation, RNAa)是一种由非编码小RNA介导的在转录及表观遗传水平的基因激活机制。能够介导RNAa的小RNA被称为小激活RNA(small activating RNA, saRNA), 它们至少包括双链小RNA(dsRNA)和microRNA(miRNA)。RNAa最早发现于人细胞,是通过转染人工设计的靶向特定启动子序列的dsRNA而实现的(Li et al., 2006),其介导的RNAa被称为外源性RNAa (图1A)。随后发现自然生成的miRNA同样能够介导RNAa;miRNA介导的RNAa(miRNAa)则为内源性RNAa (图1B)。RNAa是本课题申请人于2006年在世界上首次报道并命名(Li et al., 2006)。RNAa的发现揭示了小RNA及其共因子Argonaute(Ago)组成的RNA-Ago通路对靶基因的正性调控。此前自从RNAi发现以来,人们一直认为该通路只能通过RNAi及相关机制抑制靶序列的表达。RNAa的发现被认为是一项颠覆传统理论的重要发现,受到了《Science》(Garber, 2006)、《Nature》(Check, 2007)等的深度关注。 RNAa也被认为是一种“反标准”的非编码RNA调控模式 (张立堂 et al., 2008)。从RNAa被发现至今,世界上众多研究小组的工作证实了RNAa的存在(Hu et al., 2012; Janowski et al., 2007; Mao et al., 2008; Matsui et al., 2013; Morris et al., 2008; Qin et al., 2012; Reebye et al., 2013; Turunen et al., 2009; Voutila et al., 2012; Whitson et al., 2009)。特别是在2013年,RNAi的发现者Craig Mello及其他多个课题组在线虫中确证RNAa机制(由22G-RNA介导)的存在及其在维持基因组稳定性和生殖健康中的重要功能(Cecere et al., 2014; Conine et al., 2013; Seth et al., 2013; Wedeles et al., 2013)(文献复习见 (Guo et al., 2014)。所有这些研究证明了RNAa是一个从线虫到人细胞的进化保守现象。

1.  哺乳类细胞RNAa示意图.  A. 外源性小dsRNA介导的RNAa。由细胞外引入的靶向基因启动子的saRNA被Ago(主要为Ago2)装载形成活化的RNA-Ago复合物,RNA引导该复合物进入胞核, 在RHA的帮助下与基因启动子上的靶位点结合。Ago2进一步募集PAF1C复合物中的CTR9及PAF1,导致RNAPII 羧基末端第2及第5号丝氨酸的磷酸化及H2B的单泛素化,最终激活基因转录。B. 内源性miRNA介导的RNAa。由miRNA基因转录的原始miRNA在经DGCR8/DROSHA处理后形成前体miRNA(pre-miRNA),被XPO5外输至胞浆后进一步经Dicer处理形成成熟miRNA。miRNA与Ago(主要为Ago1)形成活化的AGO-RNA平台,进入细胞核并结合到启动子上的靶点。Ago1进一步募集其他蛋白因子如染色质修饰蛋白(CMP),引起增高的H3K4me3水平及开放的染色质结构并最终导致基因转录激活。

参考文献

  1. Cecere, G., Hoersch, S., O'Keeffe, S., Sachidanandam, R., and Grishok, A. (2014). Global effects of the CSR-1 RNA interference pathway on the transcriptional landscape. Nat Struct Mol Biol 21, 358-365.
  2. Check, E. (2007). RNA interference: hitting the on switch. Nature 448, 855-858.
  3. Conine, C.C., Moresco, J.J., Gu, W., Shirayama, M., Conte, D., Jr., Yates, J.R., 3rd, and Mello, C.C. (2013). Argonautes Promote Male Fertility and Provide a Paternal Memory of Germline Gene Expression in C. elegans. Cell 155, 1532-1544.
  4. Garber, K. (2006). Genetics. Small RNAs reveal an activating side. Science 314, 741-742.
  5. Guo, D., Barry, L., Lin, S.S., Huang, V., and Li, L.C. (2014). RNAa in action: from the exception to the norm. RNA Biol 11, 1221-1225.
  6. Hu, J., Chen, Z., Xia, D., Wu, J., Xu, H., and Ye, Z.Q. (2012). Promoter-associated small double-stranded RNA interacts with heterogeneous nuclear ribonucleoprotein A2/B1 to induce transcriptional activation. Biochem J 447, 407-416.
  7. Janowski, B.A., Younger, S.T., Hardy, D.B., Ram, R., Huffman, K.E., and Corey, D.R. (2007). Activating gene expression in mammalian cells with promoter-targeted duplex RNAs. Nat Chem Biol 3, 166-173.
  8. Li, L.C., Okino, S.T., Zhao, H., Pookot, D., Place, R.F., Urakami, S., Enokida, H., and Dahiya, R. (2006). Small dsRNAs induce transcriptional activation in human cells. Proc Natl Acad Sci U S A 103, 17337-17342.
  9. Mao, Q., Li, Y., Zheng, X., Yang, K., Shen, H., Qin, J., Bai, Y., Kong, D., Jia, X., and Xie, L. (2008). Up-regulation of E-cadherin by small activating RNA inhibits cell invasion and migration in 5637 human bladder cancer cells. Biochem Biophys Res Commun 375, 566-570.
  10. Matsui, M., Chu, Y., Zhang, H., Gagnon, K.T., Shaikh, S., Kuchimanchi, S., Manoharan, M., Corey, D.R., and Janowski, B.A. (2013). Promoter RNA links transcriptional regulation of inflammatory pathway genes. Nucleic Acids Res 41, 10086-10109.
  11. Morris, K.V., Santoso, S., Turner, A.M., Pastori, C., and Hawkins, P.G. (2008). Bidirectional transcription directs both transcriptional gene activation and suppression in human cells. PLoS genetics 4, e1000258.
  12. Qin, Q., Lin, Y.W., Zheng, X.Y., Chen, H., Mao, Q.Q., Yang, K., Huang, S.J., and Zhao, Z.Y. (2012). RNAa-mediated overexpression of WT1 induces apoptosis in HepG2 cells. World J Surg Oncol 10, 11.
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  14. Seth, M., Shirayama, M., Gu, W., Ishidate, T., Conte, D., Jr., and Mello, C.C. (2013). The C. elegans CSR-1 argonaute pathway counteracts epigenetic silencing to promote germline gene expression. Dev Cell 27, 656-663.
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2016年RNA激活(RNAa)进展大事记

 

  1. 2016.2:英国Mina Therapeutics公司开发的世界上第一个基于RNA激活的治疗肝癌的药物进入临床试验,标志着RNA激活技术正式进入临床(NIH临床试验注册号:NCT02716012)。
  2. 2016.6:国际寡核苷酸治疗协会发表社论文章,在回顾2016年该领域的进展后,充分肯定RNA激活的科学性及药物开发价值(http://www.oligotherapeutics.org/perspectives-on-current-science-june-2016/)。
  3. 李龙承课题组在Cell Research发文阐述RNA激活机制及效应复合物性质(Portnoy et al., 2016)(协和医院新闻报道:http://centrallab.pumch.cn/news/291.html)。
  4. 北京大学梁子才课题组在Nucleic Acids Research发文阐述RNA激活机制(Meng et al., 2016)(北大新闻报道:http://bdxc.pku.edu.cn/xwzh/2016-02/24/content_292875.htm)。
  5. 意大利Mallamaci课题组实现在小鼠体内激活神经元细胞Foxg1基因,恢复Foxg1蛋白功能(Fimiani et al., 2016)。
  6. 美国Chaluvally-Raghavan组在Cell Report报道miR-551b-3p通过RNA激活机制激活STAT3而在卵巢癌生长和转移中发挥作用(Chaluvally-Raghavan et al., 2016)。
  7. 复旦大学于文强组报道miRNA通过靶向增强子而激活基因表达(Xiao et al., 2016)。
  8. 美国堪萨斯大学李本义组与李龙承组合作完成了RNA激活DPYSL3基因治疗转移前列腺癌的临床前研究(Li et al., 2016a)。
  9. 美国John Rossi课题组与英国伦敦帝国学院的Habib组合作完成了CEBPA小激活RNA治疗胰腺癌的临床前研究(Yoon et al., 2016)。
  10. 第三军医大学肝胆外科研究所与英国伦敦帝国学院合作完成了CEBPA小激活RNA治疗肝癌的临床前研究(Huan et al., 2016)。
  11. 武汉同济医院妇产科Guo等报道在滋养层细胞激活VEGF基因及在治疗先兆子痫中的可能作用(Guo et al., 2016)。
  12. 中国医学科学院胡云章课题组报道在原代成纤维细胞中激活干细胞转录因子(OCT4,SOX2及NANOG)及带来的核小体定位改变(Wang et al., 2016a)。
  13. 武汉同济医院Wang等报道RNA激活p53治疗膀胱癌的临床前研究(Wang et al., 2016b)。
  14. 山东省立医院Li等报道在肺癌细胞激活PTEN激活恢复细胞对酪氨酸激酶抑制剂的敏感性(Li et al., 2016b)。
  15. 山东省立医院Xie等报道在胃癌细胞RNA激活VEZT基因(Xie et al., 2016)。
  16. 韩国Moorim Kang(本团队成员)等报道在miR-6734在结肠癌细胞通过RNA激活机制激活p21表达 (Kang et al., 2016)。
  17. 上海第九医院Xia等报道RNA激活NIS基因增加肝癌细胞的放射性碘摄入,从而有可能用于内放射治疗(Xia et al., 2016)。

参考文献:

  1. Chaluvally-Raghavan, P., Jeong, K.J., Pradeep, S., Silva, A.M., Yu, S., Liu, W., Moss, T., Rodriguez-Aguayo, C., Zhang, D., Ram, P., et al. (2016). Direct Upregulation of STAT3 by MicroRNA-551b-3p Deregulates Growth and Metastasis of Ovarian Cancer. Cell Rep 15, 1493-1504.
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  5. Kang, M.R., Park, K.H., Yang, J.O., Lee, C.W., Oh, S.J., Yun, J., Lee, M.Y., Han, S.B., and Kang, J.S. (2016). miR-6734 Up-Regulates p21 Gene Expression and Induces Cell Cycle Arrest and Apoptosis in Colon Cancer Cells. PloS one 11, e0160961.
  6. Li, C., Jiang, W., Hu, Q., Li, L.C., Dong, L., Chen, R., Zhang, Y., Tang, Y., Thrasher, J.B., Liu, C.B., et al. (2016a). Enhancing DPYSL3 gene expression via a promoter-targeted small activating RNA approach suppresses cancer cell motility and metastasis. Oncotarget 7, 22893-22910.
  7. Li, M., Peng, Z., Ren, W., and Wang, Z. (2016b). Small activating ribonucleic acid reverses tyrosine kinase inhibitor resistance in epidermal growth factor receptor-mutant lung cancer by increasing the expression of phosphatase and tensin homolog. Thorac Cancer 7, 481-485.
  8. Meng, X., Jiang, Q., Chang, N., Wang, X., Liu, C., Xiong, J., Cao, H., and Liang, Z. (2016). Small activating RNA binds to the genomic target site in a seed-region-dependent manner. Nucleic acids research 44, 2274-2282.
  9. Portnoy, V., Lin, S.H., Li, K.H., Burlingame, A., Hu, Z.H., Li, H., and Li, L.C. (2016). saRNA-guided Ago2 targets the RITA complex to promoters to stimulate transcription. Cell research 26, 320-335.
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  14. Xie, D., Shang, L., Peng, L., and Li, L. (2016). Up-regulation of VEZT by small activating RNA inhibits the proliferation, invasion and migration of gastric cancer cells. Biochemical and biophysical research communications.
  15. Yoon, S., Huang, K.W., Reebye, V., Mintz, P., Tien, Y.W., Lai, H.S., Saetrom, P., Reccia, I., Swiderski, P., Armstrong, B., et al. (2016). Targeted Delivery of C/EBPalpha -saRNA by Pancreatic Ductal Adenocarcinoma-specific RNA Aptamers Inhibits Tumor Growth In Vivo. Molecular therapy : the journal of the American Society of Gene Therapy 24, 1106-1116.