Generation and characterization of alpha-chymase-Cre transgenic mice

The Cre-loxP technology allows the introduction of somatic gene alterations in a tissue and/or cell type specific manner. The development of transgenes that target Cre expression to specific cell types is a critical component in this system. Here, we describe the generation and characterization of transgenic mouse lines expressing Cre recombinase under the control of the baboon alpha-chymase promoter, designated Chm:Cre, in order to direct Cre expression specifically to mouse mast cells. Chm:Cre expression was detected in mast cells in lung and colon tissue. Cre-mediated recombination in these mice identified a population of mature tissue resident mast cells using ROSA26R reporter mice. No Cre-expression and Cre-mediated recombination was induced in in vitro generated bone marrow derived mast cells or mast cells isolated from the peritoneal cavity indicating that Cre-expression under the control of the alpha-chymase promoter is solely activated in tissue resident mast cells. These Chm:Cre transgenic mice represent a useful tool to specifically inactivate genes of interest in mast cells of these tissues.