A Conditional System to Specifically Link Disruption of Protein-Coding Function with Reporter Expression in Mice

Abstract

Conditional gene deletion in mice has contributed immensely to our understanding of many biological and biomedical processes. Despite an increasing awareness of nonprotein-coding functional elements within protein-coding transcripts, current gene-targeting approaches typically involve simultaneous ablation of noncoding elements within targeted protein-coding genes. The potential for protein-coding genes to have additional noncoding functions necessitates the development of novel genetic tools capable of precisely interrogating individual functional elements. We present a strategy that couples Cre/loxP-mediated conditional gene disruption with faithful GFP reporter expression in mice in which Cre-mediated stable inversion of a splice acceptor-GFP-splice donor cassette concurrently disrupts protein production and creates a GFP fusion product. Importantly, cassette inversion maintains physiologic transcript structure, thereby ensuring proper microRNA-mediated regulation of the GFP reporter, as well as maintaining expression of nonprotein-coding elements. To test this potentially generalizable strategy, we generated and analyzed mice with this conditional knockin reporter targeted to the Hmga2 locus.