Spatiotemporal gene control by the Cre-ERT2 system in melanocytes.

The organ-specific and temporal control of gene activation/inactivation is a key issue in the understanding of protein function during normal and pathological development and during oncogenesis. We generated transgenic mice bearing a tamoxifen-dependent Cre recombinase (Tyr::Cre-ERT2) gene expressed under the control of a 6.1 kb murine tyrosinase promoter in order to facilitate targeted spatiotemporally controlled somatic recombination in melanoblasts/melanocytes. Cre-ERT2 production was detected in tissues containing melanocytes. After tamoxifen induction at various times during embryogenesis and adulthood in a Cre-responsive reporter mouse strain, genetic recombination was detected in the melanoblasts and melanocytes of the skin. Thus, the Tyr::Cre-ERT2 transgenic mice provides a valuable tool for following this cell lineage and for investigating gene function in melanocyte development and transformation.