Native tertiary structure and nucleoside modifications suppress tRNA's intrinsic ability to activate the innate immune sensor PKR.
Native tertiary structure and nucleoside modifications suppress tRNA's intrinsic ability to activate the innate immune sensor PKR.
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DOI：
10.1371/journal.pone.0057905
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Bevilacqua PC
中科院分区：
文献类型：
--
作者：
Nallagatla SR;Jones CN;Ghosh SK;Sharma SD;Cameron CE;Spremulli LL;Bevilacqua PC
干扰素诱导蛋白激酶PKR是先天免疫的重要组成部分。它被长链dsRNA激活，并通过抑制感染细胞中的翻译起始来提供宿主防御病原体的第一道防线。许多细胞和病毒转录物含有可能影响PKR活化的核苷修饰和/或三级结构。我们以前已经证明，5′-端三磷酸-某些病毒和细菌转录物的特征-赋予相对非结构化的模型RNA转录物激活PKR以抑制翻译的能力，并且这种激活被细胞RNA中存在的某些修饰所废除。为了了解天然RNA三级结构和核苷修饰对PKR激活的生物学意义，我们在这里研究了高度修饰的细胞tRNA和未修饰或轻度修饰的线粒体tRNA（mt-tRNA）。我们发现酵母tRNAPhe的T7转录物和天然提取的总牛肝mt-tRNA在体外激活PKR，而天然E.大肠杆菌、牛肝、酵母和小麦tRNAPhe不存在，各种碱基或糖修饰的T7转录物也不存在。这些结果进一步得到了体内tRNAPhe的天然折叠T7转录物激活PKR的支持，支持了tRNA修饰在抑制细胞中PKR激活中的重要性。我们还研究了PKR激活的T7转录的A14 G致病突变的mt-tRNALeu，这是已知的二聚体，并发现错误折叠的二聚体形式激活PKR在体外，而单体形式没有。总体而言，本文的体外和体内发现表明，tRNA具有激活PKR的内在能力，并且核苷修饰和天然RNA三级折叠可以至少部分地起到抑制这种激活的作用，从而用于区分先天免疫中的自体和非自体tRNA。
Interferon inducible protein kinase PKR is an essential component of innate immunity. It is activated by long stretches of dsRNA and provides the first line of host defense against pathogens by inhibiting translation initiation in the infected cell. Many cellular and viral transcripts contain nucleoside modifications and/or tertiary structure that could affect PKR activation. We have previously demonstrated that a 5′-end triphosphate–a signature of certain viral and bacterial transcripts–confers the ability of relatively unstructured model RNA transcripts to activate PKR to inhibit translation, and that this activation is abrogated by certain modifications present in cellular RNAs. In order to understand the biological implications of native RNA tertiary structure and nucleoside modifications on PKR activation, we study here the heavily modified cellular tRNAs and the unmodified or the lightly modified mitochondrial tRNAs (mt-tRNA). We find that both a T7 transcript of yeast tRNAPhe and natively extracted total bovine liver mt-tRNA activate PKR in vitro, whereas native E. coli, bovine liver, yeast, and wheat tRNAPhe do not, nor do a variety of base- or sugar-modified T7 transcripts. These results are further supported by activation of PKR by a natively folded T7 transcript of tRNAPhe in vivo supporting the importance of tRNA modification in suppressing PKR activation in cells. We also examine PKR activation by a T7 transcript of the A14G pathogenic mutant of mt-tRNALeu, which is known to dimerize, and find that the misfolded dimeric form activates PKR in vitro while the monomeric form does not. Overall, the in vitro and in vivo findings herein indicate that tRNAs have an intrinsic ability to activate PKR and that nucleoside modifications and native RNA tertiary folding may function, at least in part, to suppress such activation, thus serving to distinguish self and non-self tRNA in innate immunity.
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影响因子：
64.5
作者：
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通讯作者：
Dever, TE
影响因子：
6.7
作者：
Dauber B;Martínez-Sobrido L;Schneider J;Hai R;Waibler Z;Kalinke U;García-Sastre A;Wolff T
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Wolff T
影响因子：
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作者：
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通讯作者：
Bevilacqua, Philip C.
DOI：
10.1016/j.bbapap.2004.02.015
发表时间：
2004-06-01
影响因子：
3.2
作者：
Hunter, SE;Spremulli, LL
通讯作者：
Spremulli, LL
DOI：
10.1006/smvy.1993.1020
发表时间：
1993-08-01
期刊：
SEMINARS IN VIROLOGY
影响因子：
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作者：
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通讯作者：
HOVANESSIAN, AG