Conditional tamoxifen Cre induced mutagenesis in the embryonic kidney in organ culture.

Developmental control genes are often sequentially and repeatedly functional during embryogenesis, and for this reason conditional mutagenesis tools are often required to study their roles in detail. Cre recombinase fused to the modified estrogen hormone-binding domain (ER(Tm)) generates a Cre in which the recombination activity of the LoxP-containing gene can be regulated by the nonsteroidal estrogen analogue 4-hydroxytamoxifen (4OH-TM). ER(Tm) may provide a useful way of achieving conditional mutagenesis in conjunction with the classic organ culture methods of experimental embryology. We used embryonic kidneys separated from the Cre-ER(Tm); R26R embryos to assay whether efficient 4OH-TM-inducible genomic recombination can be achieved in organ culture and in experimentally induced kidney mesenchymes. Our results indicate that the inducible ER(Tm) Cre/loxP system indeed provides an effective way of conditionally mutagenizing genes in kidney organ culture and tissue conjugates. (c) 2007 Wiley-Liss, Inc.