These Csf1rfl/fl floxed mutant mice possess loxP sites flanking exon 5 of the colony stimulating factor 1 receptor (Csf1r) gene. Csf1r encodes Cd115 which acts as the receptor for colony stimulating factor 1, a cytokine which controls the production, differentiation, and function of macrophages. Expressed in macrophages, expression is also seen in oocytes, osteoclasts, trophoblasts, CNS microglia, and some myoblasts. Mice that are homozygous for this allele are viable and fertile. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have exon 5 and the neo cassette deleted in cre-expressing tissues.
For example, when crossed to B6.Cg-Tg(Nes-cre)1Kln/J mice ( Stock No. 003771), expressing Cre recombinase in the neural progenitors, resulting offspring exhibit smaller
brain size, an expanded neural progenitor pool and elevated cellular apoptosis in cortical forebrain.
When crossed to B6.FVB-Tg(Zp3-cre)3Mrt/J mice (Stock No. 003394), expressing Cre recombinase in the female germ line, resulting offspring exhibit premature death by 6 weeks of age, smaller body size, and osteoporosis. Offspring also lack teeth.
