Revista de genómica clínica y médica

Trapping Enhancers by Transgenic Expression of BACs Engineered in Bacteria with loxP Transposons

Abstract

Hope M Wolf, Kevin O Nyabera, Katya K De La Torre, Mugtaba A Eltayeb, Leighcraft A Shakes, Charles Hatcher, Derek C Norford and Pradeep K Chatterjee

Bacterial Artificial Chromosomes (BACs) are large extra-chromosomal plasmids in bacteria that faithfully propagate large pieces of DNA from the chromosomes of organisms. Because they represent tiny contiguous pieces of the chromosome, BACs are ideally suited for expression of genes in their chromosomal contexts. Genes in BACs can be monitored for expression after the DNA is modified with reporter genes and other sequences that allow it to be stably propagated in the new host. Several methods have been developed to alter BAC DNA within its bacterial host. One approach uses Tn10 mini-transposons to introduce exogenous DNA into BACs. The random insertions of Tn10 carrying lox sites have directed mammalian cell-selectable antibiotic resistance genes, enhancer-traps and inverted repeat ends of the vertebrate transposon Tol2 precisely to the ends of genomic DNA inserts in BACs. Reporter gene expression from BAC DNA integrated into zebrafish or mouse chromosomes have resulted from such retrofitting. The methodology has been used extensively to analyze regulation of the Amyloid Precursor Protein (appb) gene in zebrafish. Functional identification of long-range regulatory sequences of appb has provided important clues for regulation of the APP gene in humans.