Masking the 5′ terminal nucleotides of the hepatitis C virus genome by an unconventional microRNA-target RNA complex
Masking the 5′ terminal nucleotides of the hepatitis C virus genome by an unconventional microRNA-target RNA complex
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DOI：
10.1073/pnas.1012464108
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发表时间：
2011-02-22
影响因子：
11.1
通讯作者：
Sagan, Selena M.
中科院分区：
文献类型：
--
作者：
Machlin, Erica S.;Sarnow, Peter;Sagan, Selena M.
丙型肝炎病毒颠覆肝脏特异的microRNA，miR-122，以上调感染的培养细胞和感染的黑猩猩肝脏中的病毒RNA丰度。这些发现已经确定miR-122是一个有吸引力的抗病毒靶点。因此，了解miR-122和病毒RNA与其正常细胞靶向mRNAs之间是否存在不同的功能复合体是当务之急。为此，我们比较了突变的miR-122双链分子结合在病毒基因组的两个靶点上对病毒RNA丰度的影响，以及对microRNA或siRNA介导的报告靶mRNAs调控的影响。研究发现，miR-122与病毒RNA形成了一种不寻常的microRNA复合体，这与miR-122与报告mRNAs的复合体不同。值得注意的是，miR-122形成了一个寡聚复合体，其中一个miR-122分子与丙型肝炎病毒(丙型肝炎病毒)RNA的5‘端结合，与3’端的悬垂核苷酸结合，掩盖了丙型肝炎病毒基因组的5‘端序列。此外，特定的内部核苷酸以及miR-122中的3‘末端核苷酸是维持丙型肝炎病毒RNA丰度所绝对需要的，而不是微RNA功能所必需的。这两个miR-122分子都利用相似的内部核苷酸与病毒基因组相互作用，在miR-122分子中创建了一个凸起和一个尾巴，揭示了以DNA为导向的寡聚RNA复合体。这些发现表明，miR-122保护5‘端病毒序列免受核溶解降解或诱导对RNA末端的先天性免疫反应。最后，这种引人注目的microRNA-mRNA复合体可以被使miR-122失活或干扰这种独特RNA结构的化合物作为靶点。
Hepatitis C virus subverts liver-specific microRNA, miR-122, to upregulate viral RNA abundance in both infected cultured cells and in the liver of infected chimpanzees. These findings have identified miR-122 as an attractive antiviral target. Thus, it is imperative to know whether a distinct functional complex exists between miR-122 and the viral RNA versus its normal cellular target mRNAs. Toward this goal, effects on viral RNA abundance of mutated miR-122 duplex molecules, bound at each of the two target sites in the viral genome, were compared to effects on microRNA-or siRNA-mediated regulation of reporter target mRNAs. It was found that miR-122 formed an unusual microRNA complex with the viral RNA that is distinct from miR-122 complexes with reporter mRNAs. Notably, miR-122 forms an oligomeric complex in which one miR-122 molecule binds to the 5' terminus of the hepatitis C virus (HCV) RNA with 3' overhanging nucleotides, masking the 5' terminal sequences of the HCV genome. Furthermore, specific internal nucleotides as well as the 3' terminal nucleotides in miR-122 were absolutely required for maintaining HCV RNA abundance but not for microRNA function. Both miR-122 molecules utilize similar internal nucleotides to interact with the viral genome, creating a bulge and tail in the miR-122 molecules, revealing tandemly oriented oligomeric RNA complexes. These findings suggest that miR-122 protects the 5' terminal viral sequences from nucleolytic degradation or from inducing innate immune responses to the RNA terminus. Finally, this remarkable microRNA-mRNA complex could be targeted with compounds that inactivate miR-122 or interfere with this unique RNA structure.