DEVELOPMENT OF MHV-RESISTANT MOUSE USING RNAi TRAP METHOD

在动物和植物中，转录后基因沉默被称为RNA干扰（RNAi）。RNAi是一种双链RNA （dsRNA）诱导同源mRNA序列依赖性降解的过程。RNAi的天然作用可能诱导抵抗病毒感染和调节细胞基因的表达。遗传学和生物学研究表明，RNAi是一个非常复杂的过程，涉及许多不同的蛋白质，其中大多数功能未知。最近有报道称，21核苷酸合成的小干扰rna （siRNA）和由U6或H1启动子转录的siRNA特异性地抑制了几种哺乳动物细胞内源基因的表达。这些21-nt siRNA双链能够逃避INF防御系统，这些发现表明RNAi或RNAi相关系统可能存在于哺乳动物中。小鼠肝炎病毒（MHV）感染是当代实验室菌落中一种重要的病毒感染。最近，研究者之间频繁地交换转基因小鼠和基因敲除小鼠，导致各国MHV污染的高发生率。目前，我们没有有效的方法来预防感染，也没有任何治疗方法。预防感染的一种方法是培育抗mhv的小鼠。为此，我们尝试开发一种RNAi基因诱捕方法。我们以前成功地开发了一种可交换基因陷阱方法。利用这种方法，我们可以在小鼠身上进行大规模的诱变。如果我们能同时培育出对MHV具有抗性的基因诱捕鼠，将对这些小鼠的分布有很大的帮助。然而，我们开发的方法仍然不能有效地阻止RNA基因的表达。要达到最初的目的，还需要进一步的研究。

The post-transriptional gene silencing in animals and plants is called RNA interference (RNAi). RNAi is a process in that double-stranded RNA (dsRNA) induces a sequence-dependent degradation of a cognate mRNA. The natural roles of RNAi might induce defense against viral infection and regulation of the expression of cellular genes. Genetic and biological studies revealed that RNAi is a very complex process that involves many different proteins with mostly unidentified functions. It was reported recendy that 21-nucleotide (nt) synthetic small interfering RNAs (siRNAs) and siRNA that were transcribed by U6 or H1 promoter specifically suppressed the expression of endogenous genes in several lines of mammalian cells. These 21-nt siRNA duplexes were able to evade the INF defense system and these findings suggested that RNAi or an RNAi-related system might exist in mammals.Mouse hepatitis virus (MHV) infection is an important viral infection in contemporary laboratory colonies. Recently, transgenic and knockout mice are frequently exchanged between investigators leading to the high incidence of contamination of MHV across the countries. At present, we do not have effective methods to prevent infection, nor do we have any treatment. One way to prevent infection is to produce a MHV-resistant mouse. For this purpose, we tried to develop an RNAi gene trap method. We previouly succeeded to develop an exchangeable gene trap method. Using this method, we can carry out a large scale mutagenesis in mice. If we can produce a gene trap mouse which is resistant to MHV at the same time, it will be quite helpful to distribute these mice. However, the method we developed is not still effective to prevent RNA gene expression. Further studies will be required to accomplish the initial purpose.