Characterization ofSleeping BeautyTransposition and Its Application to Genetic Screening in Mice

Abstract

The use of mutant mice plays a pivotal role in determining the function of genes, and the recently reported germ line transposition of the Sleeping Beauty (SB) transposon would provide a novel system to facilitate this approach. In this study, we characterized SB transposition in the mouse germ line and assessed its potential for generating mutant mice. Transposition sites not only were clustered within 3 Mb near the donor site but also were widely distributed outside this cluster, indicating that the SB transposon can be utilized for both region-specific and genome-wide mutagenesis. The complexity of transposition sites in the germ line was high enough for large-scale generation of mutant mice. Based on these initial results, we conducted germ line mutagenesis by using a gene trap scheme, and the use of a green fluorescent protein reporter made it possible to select for mutant mice rapidly and noninvasively. Interestingly, mice with mutations in the same gene, each with a different insertion site, were obtained by local transposition events, demonstrating the feasibility of the SB transposon system for region-specific mutagenesis. Our results indicate that the SB transposon system has unique features that complement other mutagenesis approaches.The analysis of mutant mice plays a key role in the understanding of gene functions, and the importance of this approach is expected to increase (2) with the recent availability of the mouse genome sequence (25). However, large-scale genetic screening for mice has been lagging far behind that for other model organisms, such as Drosophila melanogaster and Caenorhabditis elegans, because of the lack of a system allowing for both mutagenesis and subsequent rapid identification of the mutation. Large-scale generation of mutant mice has been conducted recently by using N-ethyl-N-nitrosourea (ENU), and a number of mutant mice with various phenotypes have been generated successfully (6, 26). The drawback of this approach is that identification of the causative point mutations is time-consuming. The embryonic stem (ES) cell-based gene trap is another effective approach (11,12,31). However, largescale generation of mutant mice, which is a prerequisite for genetic screening, is not easy because the ES cell-based methods involve labor-intensive processes such as tissue culture or embryo manipulation.Transposon-tagged mutagenesis has been used in a wide range of organisms, such as D. melanogaster (1, 32), C. elegans (13, 24), and plants (27). Although the mutation rate resulting from transposition is not as high as that in ENU mutagenesis, transposon-tagged mutagenesis has been used as an alternative genetic screening method for the following reasons. First, the genes responsible for the phenotypes can be identified rapidly by using the transposon sequence as a tag. Second, desired elements can be introduced into the transposon sequence to expand the application range of the mutant lines. This principle has been demonstrated in the P element of D. melanogaster, where various GAL4 en...

A Sleeping Beauty mutagenesis screen reveals a tumor suppressor role for Ncoa2/Src-2 in liver cancer

“…Consistent with previous studies, we find that genome-level integration of SB with respect to genes and intergenic regions is fairly random overall (Fig. S4A) (17)(18)(19). As expected, we observe the greatest number of insertions clustering around the T2/ Onc transgene concatemer on chromosome 15 (Fig.…”

Targeted gene alteration in Caenorhabditis elegans by gene conversion

“…The gene conversion technique reported here should also be effective in this heterologous system, because the process of gene conversion, as shown by ourselves and others 20 , seems merely to require the presence of dsDNA breaks and the homologous template DNA. Similarly, the technique should work for generating targeted gene alterations in other systems, such as zebrafish and mouse, where heterologous insertion systems are also being developed [32][33][34] .…”

Large-scale, saturating insertional mutagenesis of the mouse genome

“…Finally, direct genetics approaches using random chemical (9) and insertional (see ref. 10 as an example) mutagenesis remain useful options for revealing gene functions. Each of these techniques has its advantages and drawbacks (for recent discussions, see refs.…”