Transgenic mouse with high Cre recombinase activity in all prostate lobes, seminal vesicle, and ductus deferens

BACKGROUND. Prostate-specific gene ablation provides a powerful tool for functional characterization of genes that have impact on embryonic development or on other organs, specifically in the prostate. Uniform expression of Cre with high recombinase activity in the prostate is needed for prostate-specific gene ablation based on Cre-IoxP recombinations. Currently, available strains of Cre transgenic mice only express Cre recombinase adequately in certain lobes of the prostate. In other lobes, the expression is low and mosaic. Additional strains of transgenic mice expressing high levels of prostate-specific Cre in all prostate lobes would be useful to study the impact of genome manipulation in all prostate lobes. METHODS. The ARR2PB composite promoter with improved capacity to drive androgen-responsive gene expression was used to initiate expression of a transgene bearing the cDNA encoding a recently modified Cre recombinase with improved recombination activity. In addition, an insulator element from the chicken globin locus that minimized negative effect on transcription of the transgene imposed by chromosome structure was employed. The derived transgenic founders were crossed with the Z/AP reporter mouse and Fgfr2(f/f) mice bearing IoxP flanking the FGFR2 locus. Immunochemical and mRNA analyses were employed to test expression and efficacy of the Cre recombinase in the prostate and other tissues. RESULTS. The ARR2PBi-Cre transgenic mouse specifically and uniformly expressed Cre recombinase in the dorsal, lateral, ventral, and anterior lobes of the prostate, seminal vesicles, and ductus deferens. The Cre recombinase in these tissues effectively excised IoxP flanked DNA fragments in the Z/AP reporter that triggered expression of beta-galactosidase, and the IoxP-flanked FGFR2(f/f) locus resulting in specific ablation of FGFR2 in the prostate. CONCLUSIONS. Compared with the currently available prostate-specific Cre strains, the new ARR2PBi-Cre strain exhibited higher and more uniform expression of Cre recombinase in the prostate as well as in seminal vesicles and ductus deferens. This provides an additional tool for efficient hormone-dependent gene targeting in epithelial cells of all lobes of the adult prostate, seminal vesicle, and ductus deferens. (C) 2003 Wiley-Liss, Inc.