Tg(Col2a1-rtTA,tetO-cre)22Pjro

The construct was generated such that a 6 kb fragment of the Col2a1 gene (composed of 3 kb of promoter and 3 kb of intron 1 containing an enhancer sequence) controls the reverse tetracycline transactivator sequence. A tetracycline responsive element heptad sequence (tetO) with a CMV minimal promoter is upstream of the cre recombinase coding sequence in this construct. Cre expression can only occur by transactivation of rtTA by doxycycline. The linearized construct was injected into fertilized oocytes and founder mice were obtained (lines 13, 12, 22, and 24). Cre mRNA expression was detected only in cartilage, not in the brain, liver or skin of embryos exposed to doxycycline. (J:107728)