Nomenclature: B6.Cg-Tg(Lck-cre)1Cwi N9

In order to selectively inactivate genes in a tissue specific manner many laboratories have developed Cre transgenic mouse strains in which the Cre recombinase is expressed under the control of a tissue specific promoter. The Lck-Cre transgenic mouse uses the proximal promoter of the Lck (lymphocyte protein tyrosine kinase) gene, which is first expressed early in thymocyte development at the double negative stage. After T cells fully mature, the level of expression of this transgene decreases by approximately 10 fold. This particular mouse shows a high degree of expression of the transgene in the thymus and has been found to bring about the selective deletion of genes flanked by loxP targeting sequences in almost all early thymocytes. It thus will be useful for experiments designed to delete a specific gene in the T cell lineage starting at the double negative stage. Since the Lck-Cre transgene in this strain has been made homozygous, one can simply cross the mouse to any strain containing a floxed gene of interest and obtain offspring that have deleted it in this tissue specific manner. If your strain is heterozygous, you can also obtain control animals in the same litter by typing for the presence or absence of the floxed gene in genomic DNA tail samples. Dr. Chris Wilson has recently discovered that his Lck-Cre transgenic mouse can cause partial to complete deletion in non-lymphoid tissues in some mice on certain backgrounds. These occurrences are unpredictable, but are apparent in tail DNA samples. Investigators should determine whether this abnormality is present in their crosses. Aberrant deletion had not been observed with the Cd4-Cre mouse (line 4196) developed by Dr. Wilson.

Note:This model has replaced Model 4204-M. It has been further backcrossed to C57BL/6 for a total of 9 generations.

Origin