Department of Neurosurgery, Duke University Medical Center, Durham, North Carolina, USA.
University Program in Genetics and Genomics, Duke University Medical Center, Durham, North Carolina, USA.
mBio. 2021 Apr 13;12(2):e00116-21. doi: 10.1128/mBio.00116-21.
Enteroviruses (EV) deploy two proteases that mediate viral polyprotein cleavage and host cell manipulation. Here, we report that EV 2A proteases cleave all three members of the YTHDF protein family, cytosolic -methyladenosine (mA) "readers" that regulate target mRNA fate. YTHDF protein cleavage occurs very early during infection, before viral translation is detected or cytopathogenic effects are observed. Preemptive YTHDF protein depletion enhanced viral translation and replication but only in cells with restrained viral translation, signs of inefficient 2A protease activity, and protective innate host immune responses. This effect corresponded with repression of interferon (IFN)-stimulated gene (ISG) induction, while type I/III IFN production was not significantly altered. Moreover, YTHDF3 depletion impaired JAK/STAT signaling in cells treated with type I, but not type II, IFN. YTHDF3 depletion's stimulatory effect on viral dynamics was dampened by JAK/STAT blockade and enhanced by type I IFN pretreatment of cells. We propose that EV 2A proteases cleave YTHDF proteins to antagonize ISG induction in infected cells. It is believed that ∼7,000 messenger RNAs (mRNAs) are subject to -methyladenosine modification. The biological significance of this remains mysterious. The YTHDF mA readers are three related proteins with high affinity for mA-modified mRNA, yet their biological functions remain obscure. We discovered that polio/enteroviruses elicit very early proteolysis of YTHDF1 to 3 in infected cells. Our research demonstrates that YTHDF3 acts as a positive regulator of antiviral JAK/STAT signaling in response to positive single-strand RNA virus infection, enabling type I interferon (IFN)-mediated gene regulatory programs to unfurl in infected cells. Our observation of viral degradation of the YTHDF proteins demonstrates that they are key response modifiers in the innate antiviral immune response.
肠道病毒(EV)利用两种蛋白酶来介导病毒多蛋白的切割和宿主细胞的操作。在这里,我们报告 EV 2A 蛋白酶可以切割 YTHDF 蛋白家族的所有三个成员,细胞质 -甲基腺苷(mA)“读取器”,调节靶 mRNA 的命运。YTHDF 蛋白的切割发生在感染的早期,在检测到病毒翻译或观察到细胞病变效应之前。在病毒翻译受到限制、2A 蛋白酶活性效率低下以及先天宿主免疫反应受到保护的细胞中,抢先耗尽 YTHDF 蛋白会增强病毒的翻译和复制。这种效应与干扰素(IFN)刺激基因(ISG)诱导的抑制相对应,而 I 型/III 型 IFN 的产生没有明显改变。此外,YTHDF3 的缺失会削弱细胞中 I 型 IFN 处理后的 JAK/STAT 信号转导。YTHDF3 缺失对病毒动力学的刺激作用被 JAK/STAT 阻断减弱,而被细胞中 I 型 IFN 的预处理增强。我们提出,EV 2A 蛋白酶切割 YTHDF 蛋白以拮抗感染细胞中的 ISG 诱导。据信,大约有 7000 个信使 RNA(mRNA)受到 -甲基腺苷修饰。其生物学意义仍然神秘。YTHDF mA 读取器是三个与 mA 修饰的 mRNA 具有高亲和力的相关蛋白,但它们的生物学功能仍不清楚。我们发现脊髓灰质炎/肠道病毒在感染细胞中引发 YTHDF1 至 3 的早期蛋白水解。我们的研究表明,YTHDF3 作为抗病毒 JAK/STAT 信号的正调节剂,在应对正单链 RNA 病毒感染时发挥作用,使 I 型干扰素(IFN)介导的基因调控程序在感染细胞中展开。我们观察到病毒对 YTHDF 蛋白的降解表明,它们是先天抗病毒免疫反应中的关键反应调节剂。