Key Laboratory of Molecular Microbiology and Technology, Ministry of Education, College of Life Sciences, Nankai University, Tianjin 300071, P.R. China.
Division of Biology, Kansas State University, Manhattan, KS 66506, USA.
Int J Mol Med. 2021 Apr;47(4). doi: 10.3892/ijmm.2021.4889. Epub 2021 Feb 19.
The Fos proto‑oncogene, activator protein‑1 (AP‑1) transcription factor subunit () gene, a member of the immediate early gene family, encodes c‑Fos, which is a subunit of the AP‑1 transcription factor. The present study aimed to investigate the mechanism by which the translation efficiency of mRNA is upregulated when cellular protein synthesis is shut off. The result of western blotting revealed that the protein expression levels of c‑Fos were increased in rhabdomyosarcoma cells infected with enterovirus 71 (EV71) compared with uninfected cells. PCR was used to get the 5'‑untranslated region (UTR). The luciferase assay of a bicistronic vector containing the 5'UTR revealed that the 5'UTR contains an internal ribosome entry site (IRES) sequence and a 175 nucleotide sequence (between 31 and 205 nt) that is essential for IRES activity. Analysis of potential IRES trans‑acting factors revealed that poly(C)‑binding protein 2 (PCBP2) negatively regulated the activity of the IRES, whereas the La autoantigen (La) positively regulated its activity. The results of RNA‑protein immunoprecipitation demonstrated that both PCBP2 and La bound to the 5'UTR. Furthermore, the IRES activity of ‑transcribed mRNA was upregulated during EV71 infection. The present study suggested a mechanism for the effect of viral infection on host genes, and provided a novel target for gene translation regulation.
原癌基因 Fos，激活蛋白 1（AP-1）转录因子亚基（）基因，是即刻早期基因家族的成员，编码 c-Fos，它是 AP-1 转录因子的一个亚基。本研究旨在探讨当细胞蛋白质合成关闭时，mRNA 翻译效率上调的机制。Western blot 结果显示，感染肠道病毒 71（EV71）的横纹肌肉瘤细胞中 c-Fos 蛋白表达水平升高，而非未感染细胞。通过 PCR 获得 5'-非翻译区（UTR）。双顺反子载体的荧光素酶测定显示，5'-UTR 含有内部核糖体进入位点（IRES）序列和 175 个核苷酸序列（31-205nt），对于 IRES 活性是必需的。对潜在的 IRES 反式作用因子的分析表明，多聚（C）结合蛋白 2（PCBP2）负调控 IRES 的活性，而 La 自身抗原（La）则正调控其活性。RNA-蛋白免疫沉淀的结果表明，PCBP2 和 La 均与 5'-UTR 结合。此外，在 EV71 感染过程中，-转录的 mRNA 的 IRES 活性上调。本研究提出了病毒感染对宿主基因的影响机制，并为基因翻译调控提供了一个新的靶点。
