Kulmann Marcos Iuri Roos, Taborska Eliska, Benköova Brigita, Palus Martin, Drobek Ales, Horvat Filip, Pasulka Josef, Malik Radek, Salyova Eva, Hönig Vaclav, Pellerova Michaela, Borsanyiova Maria, Nedvedova Lenka, Stepanek Ondrej, Bopegamage Shubhada, Ruzek Daniel, Svoboda Petr
Laboratory of Epigenetic Regulations, Institute of Molecular Genetics of the Czech Academy of Sciences, Videnska 1083, 142 20, Prague, Czech Republic.
Faculty of Medicine, Enterovirus Laboratory, Institute of Microbiology, Slovak Medical University, Limbova 12, 83303Bratislava, Slovakia.
Nucleic Acids Res. 2025 Jan 7;53(1). doi: 10.1093/nar/gkae1288.
In RNA interference (RNAi), long double-stranded RNA is cleaved by the Dicer endonuclease into small interfering RNAs (siRNAs), which guide degradation of complementary RNAs. While RNAi mediates antiviral innate immunity in plants and many invertebrates, vertebrates have adopted a sequence-independent response and their Dicer produces siRNAs inefficiently because it is adapted to process small hairpin microRNA precursors in the gene-regulating microRNA pathway. Mammalian endogenous RNAi is thus a rudimentary pathway of unclear significance. To investigate its antiviral potential, we modified the mouse Dicer locus to express a truncated variant (DicerΔHEL1) known to stimulate RNAi and we analyzed how DicerΔHEL1/wt mice respond to four RNA viruses: coxsackievirus B3 and encephalomyocarditis virus from Picornaviridae; tick-borne encephalitis virus from Flaviviridae; and lymphocytic choriomeningitis virus (LCMV) from Arenaviridae. Increased Dicer activity in DicerΔHEL1/wt mice did not elicit any antiviral effect, supporting an insignificant antiviral function of endogenous mammalian RNAi in vivo. However, we also observed that sufficiently high expression of DicerΔHEL1 suppressed LCMV in embryonic stem cells and in a transgenic mouse model. Altogether, mice with increased Dicer activity offer a new benchmark for identifying and studying viruses susceptible to mammalian RNAi in vivo.
在RNA干扰（RNAi）过程中，长双链RNA被Dicer核酸内切酶切割成小干扰RNA（siRNA），这些小干扰RNA引导互补RNA的降解。虽然RNAi在植物和许多无脊椎动物中介导抗病毒天然免疫，但脊椎动物采用了一种不依赖序列的反应，并且它们的Dicer产生siRNA的效率很低，因为它适合在基因调控的微小RNA途径中加工小发夹微小RNA前体。因此，哺乳动物内源性RNAi是一条意义不明的基本途径。为了研究其抗病毒潜力，我们对小鼠Dicer基因座进行了修饰，以表达一种已知能刺激RNAi的截短变体（DicerΔHEL1），并分析了DicerΔHEL1/wt小鼠对四种RNA病毒的反应：来自小RNA病毒科的柯萨奇病毒B3和脑心肌炎病毒；来自黄病毒科的蜱传脑炎病毒；以及来自沙粒病毒科的淋巴细胞性脉络丛脑膜炎病毒（LCMV）。DicerΔHEL1/wt小鼠中Dicer活性的增加并未引发任何抗病毒作用，这支持了内源性哺乳动物RNAi在体内的抗病毒功能微不足道。然而，我们还观察到，DicerΔHEL1的足够高表达在胚胎干细胞和转基因小鼠模型中抑制了LCMV。总之，Dicer活性增加的小鼠为在体内鉴定和研究对哺乳动物RNAi敏感的病毒提供了一个新的基准。
