Abstract
Abstract: :
Purpose: The purpose of these experiments was to create mice that would be useful for gene deletion experiments in the lens. The ability of a single inserted Pax-6 consensus site within the αA-crystallin promoter was systematically tested for its ability to influence the expression pattern of Cre recombinase driven by this promoter. Methods: Transgenic mice were generated with constructs that use two different αA-crystallin promoters to drive Cre expression. One construct used the CPV2 promoter that contains the short (-290/+43) αA-crystallin promoter. The other construct (CPV14) was identical with the exception of a single Pax6 consensus binding site inserted within the promoter fragment. The constructs were injected either alone or together with tyrosinase minigene cassette into fertilized one-cell FVB mouse embryos to produce transgenic mice. The tyrosinase minigene cassette was co-injected to facilitate the identification of potential transgenic founders via correction of albinism. Transgenic Cre expression was evaluated by in-situ hybridization, immuno-histochemistry and by mating to ROSA26 Cre-reporter mice where LacZ expression is dependent on Cre-mediated DNA recombination. Results: All 7 transgenic lines made with the CPV14 promoter exhibit Cre expression in the lens epithelium, and 4 of these lines express Cre in the entire lens epithelium and 2 of these lines exhibit some lens epithelial expression. All 7 transgenic lines made with the CPV2 promoter expressed Cre in the lens fibers, but only 2 lines demonstrated any expression in the lens epithelium, and in these 2 lines, Cre expression was only detected in a minority of epithelial cells. Of the 12 transgenic mouse lines co-injected with tyrosinase minigene cassette, Cre expression was detected in several ocular tissues beyond lens. However, in the two transgenic mouse lines produced by injection of only CPV2 or CPV14, ocular Cre expression was restricted to the lens. Both CPV2 and CPV14 constructs exhibited similar extralenticular expression when co-injected with the tyrosinase minigene. None of the transgenic mice exhibited any obvious ocular abnormalities. Conclusion:Although the short endogenous αA-crystallin promoter in CPV2 was able to drive transgene expression to the lens fibers, the insertion of a single Pax 6 binding site modifying the αA-crystallin promoter (CPV14) led to Cre expression in both the lens epithelium and fiber cells in transgenic mice. Co-injection of tyrosinase minigene cassette may interfere with the ocular expression pattern of transgenes driven by the αA-crystallin promoter.
Keywords: 606 transgenics/knock-outs • 417 gene/expression • 420 genetics