Motsch Natalie, Pfuhl Thorsten, Mrazek Jan, Barth Stephanie, Grässer Friedrich A
Institute of Virology, University of Saarland Medical School, Homburg, Germany.
RNA Biol. 2007 Nov;4(3):131-7. doi: 10.4161/rna.4.3.5206.
MicroRNAs (miRNAs) are involved in sequence-specific cleavage, translational repression or deadenylation of specific target mRNAs resulting in post-transcriptional gene silencing. Epstein-Barr Virus (EBV) infection induces cellular non-coding (nc)RNAs e.g., the "vault" RNAs or miRNAs such as miR-21, miR-155 or miR-146a. MiR-146a is upregulated in various tumours and plays a role in innate immunity. We show that the EBV-encoded latent membrane protein 1 (LMP1) induces the expression of miR-146a via NFkappaB. LMP1 activates the miR-146a promoter but not a promoter with a mutation of the NFkappaB-response elements. Conversely, a LMP1-mutant deficient in NFkappaB-activation failed to activate the promoter. The "CAO"-LMP1 variant which has an increased potential to induce NFkappaB also showed a higher ability to activate the miR-146a promoter as compared to standard B95.8-LMP1. Northern blotting revealed high levels of miR-146a and miR-155 in the Burkitt's lymphoma cell line Jijoye which expresses LMP1 while the LMP1-deficient P3HR1 mutant derived from Jijoye expresses less miR-146a or miR-155. Likewise, EBV-latency type I Burkitt's lymphoma cells with low LMP1 levels also contain low levels of either miR-146a or miR-155 while their levels are increased in LMP1-expressing EBV-latency type III BL cells. Expression of LMP1 in P3HR1 cells upregulates miR-146a levels. Neither miR-146a nor miR-155 are detectable in BCBL-1 cells transformed by the Kaposi-Sarcoma Herpes virus (KSHV/HHV8). It is possible that the induction of miR-146a plays a role in the induction or maintenance of EBV latency by modulating innate immune responses to the virus infected host cell.
微小RNA（miRNA）参与特定靶标mRNA的序列特异性切割、翻译抑制或去腺苷酸化，从而导致转录后基因沉默。爱泼斯坦-巴尔病毒（EBV）感染可诱导细胞非编码（nc）RNA，例如“穹窿体”RNA或miRNA，如miR-21、miR-155或miR-146a。miR-146a在多种肿瘤中上调，并在固有免疫中发挥作用。我们发现EBV编码的潜伏膜蛋白1（LMP1）通过核因子κB（NFκB）诱导miR-146a的表达。LMP1激活miR-146a启动子，但不激活具有NFκB反应元件突变的启动子。相反，缺乏NFκB激活能力的LMP1突变体无法激活该启动子。与标准的B95.8-LMP1相比，具有更高诱导NFκB潜力的“CAO”-LMP1变体也表现出更高激活miR-146a启动子的能力。Northern印迹分析显示，表达LMP1的伯基特淋巴瘤细胞系Jijoye中miR-146a和miR-155水平较高，而源自Jijoye的缺乏LMP1的P3HR1突变体表达的miR-146a或miR-155较少。同样，LMP1水平较低的EBV潜伏I型伯基特淋巴瘤细胞中miR-146a或miR-155水平也较低，而在表达LMP1的EBV潜伏III型BL细胞中它们的水平升高。在P3HR1细胞中表达LMP1可上调miR-146a水平。在由卡波西肉瘤疱疹病毒（KSHV/HHV8）转化的BCBL-1细胞中检测不到miR-146a和miR-155。miR-146a的诱导可能通过调节对病毒感染宿主细胞的固有免疫反应，在EBV潜伏的诱导或维持中发挥作用。
