Twist2-cre (or, Dermo1-cre) mutant mice harbor a Cre recombinase "knock-in" allele that also abolishes endogenous Twist2 gene function. Heterozygotes are viable and fertile, while homozygotes (twist-2-/-) die a few days after birth. Under control of the upstream promoter/enhancer elements, cre expression is observed in a pattern consistent with the wildtype gene; Cre recombinase activity is reported in mesoderm as early as embryonic day 9.5, in mesodermal tissues such as branchial arches and somites, and in condensed mesenchyme-derived chondrocytes and osteoblasts. When heterozygotes are bred with mice containing a loxP-flanked sequence of interest, Cre-mediated recombination will result in deletion of the floxed sequences in Dermo1-expressing tissues of the offspring. Homozygous mice exhibit elevated expression of pro-inflammatory cytokines resulting in perinatal death from cachexia (wasting), as well as progressive growth retardation, impaired movement, thin skin with sparse hair, and severe subcutaneous and internal fat deficiency.
In an attempt to offer alleles on well-characterized or multiple genetic backgrounds, alleles are frequently moved to a genetic background different from that on which an allele was first characterized. It should be noted that the phenotype could vary from that originally described. We will modify the strain description if necessary as published results become available.
