RNA structures that resist degradation by Xrn1 produce a pathogenic Dengue virus RNA.
RNA structures that resist degradation by Xrn1 produce a pathogenic Dengue virus RNA.
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DOI：
10.7554/elife.01892
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发表时间：
2014-04-01
期刊：
影响因子：
7.7
通讯作者：
Kieft JS
中科院分区：
文献类型：
--
作者：
Chapman EG;Moon SL;Wilusz J;Kieft JS
登革热病毒是一种日益严重的全球健康威胁。登革热和其他黄病毒征用宿主细胞的RNA降解机制来产生小黄病毒RNA（sfRNA），这是一种诱导细胞病变和致病的非编码RNA。宿主细胞核酸外切酶Xrn1可能装载在病毒基因组RNA的5 ′端，并通过约10 kB的RNA降解前体，在病毒RNA的3 ′端附近停止。存活的RNA是sfRNA。我们询问了完整的登革热2 sfRNA的结构，鉴定了五种独立折叠的RNA结构，其中两种定量赋予Xrn1抗性。我们开发了一种用于实时监测Xrn1抗性的检测方法，我们将其与诱变和RNA折叠实验一起使用，以显示Xrn1抗性RNA采用围绕三通接头组织的特定折叠。破坏连接的折叠消除了感染黄病毒的人类细胞中疾病相关sfRNA的积累，直接将RNA结构与sfRNA产生联系起来。地球仪上超过40%的人有被感染登革热病毒的蚊子叮咬的危险。每年，这些人中有1亿多人受到感染。许多人会出现严重的头痛、疼痛和发烧，但有些人会出现危及生命的情况，即体内的微小血管开始渗漏。如果不迅速治疗，这种更严重的疾病表现可能导致死亡。目前还没有针对登革热或许多其他密切相关的病毒（如西尼罗河病毒和日本脑炎病毒）的特定疗法或疫苗。这些病毒使用编码在单链RNA中的指令来接管受感染的细胞并进行繁殖。这些病毒还利用细胞用来破坏RNA的酶来产生称为sfRNA的短链RNA，除其他外，这可能有助于病毒避开宿主的免疫系统。准确了解登革热和其他病毒如何阻碍这种称为Xrn 1的酶，可能有助于科学家开发针对这些疾病的治疗方法或疫苗。Chapman等人现在已经证明登革病毒RNA含有许多RNA元件，这些元件可以防止它被Xrn1酶完全降解。特别是，由三个RNA螺旋形成的连接对于阻止酶的轨迹至关重要，留下疾病相关的sfRNA。登革热RNA中的一个突变破坏了三螺旋连接的结构，并允许酶完全破坏RNA。西尼罗河病毒RNA也发生了类似的突变，当人类细胞感染突变的西尼罗河病毒时，不会产生短sfRNA。因此，针对这种结构的治疗或疫苗可能有助于减少与登革热和相关病毒相关的疾病。DOI：www.example.com网站
Dengue virus is a growing global health threat. Dengue and other flaviviruses commandeer the host cell’s RNA degradation machinery to generate the small flaviviral RNA (sfRNA), a noncoding RNA that induces cytopathicity and pathogenesis. Host cell exonuclease Xrn1 likely loads on the 5′ end of viral genomic RNA and degrades processively through ∼10 kB of RNA, halting near the 3′ end of the viral RNA. The surviving RNA is the sfRNA. We interrogated the architecture of the complete Dengue 2 sfRNA, identifying five independently-folded RNA structures, two of which quantitatively confer Xrn1 resistance. We developed an assay for real-time monitoring of Xrn1 resistance that we used with mutagenesis and RNA folding experiments to show that Xrn1-resistant RNAs adopt a specific fold organized around a three-way junction. Disrupting the junction’s fold eliminates the buildup of disease-related sfRNAs in human cells infected with a flavivirus, directly linking RNA structure to sfRNA production. DOI: http://dx.doi.org/10.7554/eLife.01892.001 More than 40% of people around the globe are at risk of being bitten by mosquitoes infected with the virus that causes Dengue fever. Every year, more than 100 million of these individuals are infected. Many develop severe headaches, pain, and fever, but some develop a life-threatening condition where tiny blood vessels in the body begin to leak. If not treated quickly, this more severe manifestation of the illness can lead to death. There are currently no specific therapies or vaccines against Dengue or many other closely related viruses such as West Nile and Japanese Encephalitis. These viruses use instructions encoded in a single strand of RNA to take over an infected cell and to reproduce. The viruses also exploit an enzyme that cells use to destroy RNA to instead produce short stretches of RNA called sfRNAs that, among other things, may help the virus to avoid the immune system of its host. Understanding exactly how Dengue and other viruses thwart this enzyme—which is called Xrn1—may help scientists develop treatments or vaccines for these diseases. Chapman et al. have now shown that Dengue virus RNA contains a number of RNA elements that prevent it being completely degraded by the Xrn1 enzyme. In particular, a junction formed by three RNA helixes is critical for stopping the enzyme in its tracks, leaving the disease-associated sfRNA behind. A single mutation in the Dengue RNA disrupts the structure of the three-helix junction and allows the enzyme to completely destroy the RNA. A similar mutation was also made in the West Nile virus RNA and when human cells were infected with the mutated West Nile virus, the short sfRNAs were not produced. Treatments or vaccines targeting this structure may therefore help reduce illness associated with Dengue and related viruses. DOI: http://dx.doi.org/10.7554/eLife.01892.002