Col1a1^{tm25(tetO-cre/PhoCl/ERT2,CAG-rtTA)Nki}

RMCE retargeted Col1a1tm22Nki, to replace the F3/frt flanked PGK-Puro casette in the 3' UTR of Cola1a by a "RMCE" plasmid encoding F3-TRE3GV-Cre-PhoCl-2xERT2-CAG-rtTA(Tet-On 3G)-frt , by cotransfecting a Flpe-expressing plasmid to facilitate recombination into the 3' UTR of the Col1a1 locus. The transgene is a F3/FRT flanked hybrid gene, consisting of a Tet-responsive promoter that can be activated by binding of Tet-On3G, a Cre recombinase, a photocleavable protein (PhoCl) that dissociates into two fragments after light-induced cleavage and 2xERT2. It is followed by the CAG promoter which drives the expression of a modified artificial transcription factor (Tet-On3G) that binds to and activates promoters containing the tet operator in the presence of doxycycline. This resulted in a doxycycline- and light inducible Cre recombinase (DiLiCre2.0) mouse line. When treated with doxycycline the photoconvertible fluorescent protein (PhoCl) emits a green light, upon 405nm light illumination the fluorescent protein switches from green to an unstable red fluorescent protein which cleaves within minutes, releasing Cre from the ER and allowing it to translocate to the nucleus. The protein will also translocate intact (including its Cre recombinase activity) from the ER to the nucleus upon treatment with tamoxifen. (J:330674)