Csf1r-iCre transgenic mice express a codon optimized Cre recombinase (iCre) under the control of the murine colony stimulating factor 1 receptor promoter (Csf1r). Csf1r encodes Cd115 which acts as the receptor for colony stimulating factor 1, a cytokine which controls the production, differentiation, and function of macrophages. Homozygotes are viable and fertile. iCre expression is seen in in macrophages and dendritic cells of the liver, spleen, intestine, heart, kidney, and muscle. Expression is also seen in 80% of bone marrow derived macrophages, 50% of bone marrow derived granulocytes, and splenic T lymphocytes.
When crossed with a strain containing a loxP site-flanked sequence, iCre-mediated recombination results in deletion of the flanked sequence in these Csf1r+ cells.
For example, when bred to mice containing a conditional Stat3 allele (see B6.129S1-Stat3tm1Xyfu/J Stock No. 016923), the resulting mice develop inflammation in the intestines with tumor lesions similar to those observed in patients with inflammatory bowel disease.
