New Gene Function Tool Could Replace Cre-lox System

An alternative to the Cre-lox system that overcomes some of its technical problems has been developed by scientists at the National Center for Cardiovascular Research. According to a paper published today in Nature Communications, liSuRe-Cre provides certainty in Cre-inducible genetic modifications, a key technique for understanding gene function.

Most analysis of gene function in biomedical research relies on the use of Cre-lox technology. Since its introduction in 1994, this technology has revolutionized biomedical science because it allows scientists to eliminate or activate the function of any gene in any cell type in the mouse. Cre-Lox technology allows the regulation of gene expression at any time or in any cell type thanks to the ability of the Cre recombinase protein to recognize and recombine lox sites introduced at specific locations in the mouse genome, leading to the deletion of the genes being studied.

Despite the major impact of Cre-loxP technology on biomedical research, numerous studies have demonstrated the need for caution in its use. The main problem is that often the Cre activity level is insufficient to fully recombine and eliminate expression of the target gene, generating uncertainty about whether the desired genetic modification has been achieved.

The new method is based on a new allele called iSuRe-Cre, which is compatible with all existing Cre/CreERT2/lox alleles and guarantees high Cre activity in the cells that express the fluorescent reporter. This ultimately increases the efficiency and reliability of the analysis of Cre-dependent gene function. Moreover, the use of the new iSuRe-Cre mice permits the induction of multiple genetic deletions in the same cell. This important property allows the study of functional genetic interactions or epistasis, or in other words, how the function of one or more genes depends on the function of another.

"The use of this new genetic tool will significantly change research projects that depend on the Cre-lox system, because now we can see and be confident about the location of cells that have one or more genes eliminated," explains first author Macarena Fernández-Chacón.

Image: Single cells expressing the iSuRe-Cre allele (in yellow) and the conventional reporter (in green). Only the yellow cell has the gene deleted. Image courtesy of CNIC.