Highly B lymphocyte-specific tamoxifen inducible transgene expression of CreER T2 by using the LC-1 locus BAC vector.

The generation of cell type specific inducible Cre transgenic mice is the most challenging and limiting part in the development of spatio-temporally controlled knockout mouse models. Here we report the generation and characterization of a B lymphocyte-specific tamoxifen-inducible Cre transgenic mouse strain, LC-1-hCD19-CreER(T2). We utilized the human CD19 promoter for expression of the tamoxifen-inducible Cre recombinase (CreER(T2)) gene, embedded in genomic sequences previously reported to give minimal position effects after transgenesis. Cre recombinase activity was evaluated by cross-breeding the LC-1-hCD19-CreER(T2) strain with a strain containing a floxed gene widely expressed in the hematopoietic system. Cre activity was only detected in the presence of tamoxifen and was restricted to B lymphocytes. The efficacy of recombination ranged from 27 to 61% in the hemizygous and homozygous mice 2 respectively. In conclusion, the LC-1-hCD19-CreER(T2) strain is a powerful tool to study gene function specifically in B lymphocytes at any chosen time point in the lifecycle of the mouse. genesis 47:729-735, 2009. (C) 2009 Wiley-Liss, Inc.