miRNA Transgene Technology

Abstract

The miRNA-targeting or miRNA-gain-of-function technologies introduced in Chaps. 3–5 can only create transient forced expression of miRNAs in in vitro conditions, which may be inadequate when the research or therapy requires long-lasting, stable overexpression of miRNAs for in vivo evaluation of function consequent to miRNA-targeting. Transgenic mice models have been used to tackle the problem. There are in general two different approaches for establishing miRNA transgene animals. One is the conventional transgene approach that has been widely used for protein-coding genes. This approach was first applied to miRNA research in 2006 by Costinean et al. [Proc Natl Acad Sci USA 103:7024–7029, 2006] and Peng et al. [Proc Natl Acad Sci USA 103:2252–2256, 2006], then in 2007 by Lu et al. [Dev Biol 310:442–453, 2007], and recently by us as well Zhang et al. [Science, 2009]. The second is a creative approach utilizing artificial intronic miRNAs generated by inserting a transposon into the intron of a protein-coding gene, which was originally developed by Ying's laboratory in 2003 [Lin SL, Chang D, Wu DY, Ying SY, Biochem Biophys Res Commun 310:754–760, 2003; Lin SL, Chang SJ, Ying SY, Methods Mol Biol 342:321–334, 2006]. The miRNA-transgene technology belongs to the “miRNA-targeting” and “miRNA-gain-of-function” strategy and is primarily used for studying miRNA target genes, cellular function and pathological role in animal models. This strategy is largely based on the concept of ‘miRNA as a Regulator of a Cellular Function’ introduced in Sect. 2.1.2.