These Dlk1flox mice possess loxP sites flanking the last two exons of the delta-like 1 homolog (Dlk1) gene. Dlk1 is an epidermal growth factor (EGF)-like protein expressed from the paternal allele in skeletal muscle and cartilage. Expression is also seen in the developing pituitary gland, pancreas, lung, adrenal gland, and placenta. Since Dlk1 is paternally inherited, the donating investigator maintains these mice as heterozygotes, with the mutated allele always originating from the male parent. When these mutant mice are bred to mice that express Cre recombinase, resulting offspring will have the last two exons deleted in cre-expressing tissues. Because Dlk1 is imprinted and only expressed from the paternal allele, breeding Dlk1flox males with cre-expressing females is required to generate deleted offspring with the knockout phenotype.
For example, when males are crossed to
B6.129S4-Myf5tm3(cre)Sor/J (Stock No. 007893) females expressing Cre recombinase in muscle progenitor cells, resulting mice exhibit defective muscle development, elevated inflammatory responses, and delayed muscle regeneration.
