Calb1-dgCre (DHFR-EGFP-Cre) Mouse

The TAG stop codon was replaced with the T2A-dgCre (DHFR-EGFP-Cre) cassette. Cre recombinase and enhanced green fluorescent protein (EGFP) are expressed under the regulatory control of Calb1 gene elements. The DHFR (dihydrofolate reductase) fragment, derived from the N-terminal 159 amino acids of E. coli ecDHFR, functions as a destabilizing domain (DD). In the absence of specific ligands like TMP (Trimethoprim), this fragment leads to the rapid proteasomal degradation of Cre recombinase. This mechanism allows for the temporal-specific induction of Cre recombinase activity by regulating DHFR-Cre stability with small molecules such as TMP. In addition to studies of Cre recombinase-mediated gene recombination, this model can also be used for EGFP fluorescent protein tracing studies.