AAV with Enh358MCK promoter driven CreERT2

This AAV expresses CreERT2 driven by a muscle Enh358MCK promoter.

Muscle creatine kinase (MCK) is highly active in all striated muscles. MCK is the most abundant non-mitochondrial mRNA that is expressed in all skeletal muscle fiber types and is also highly active in cardiac muscle. The main regulatory regions in the murine MCK gene include a 358 bp proximal promoter and a muscle-specific, 200bp enhancer located approximately 1.1 kb away from the transcription start site. The muscle-specific enhancer contains 2 copies of E-Boxes, which are believed to be critical for the enhancer activity. Enh358MCK (Enh stands for enhancer, and 358MCK stands for the 358bp MCK proximal promoter) is constructed by ligating the ~200bp enhancer with the 358 bp proximal promoter of the murine MCK gene. This artificial promoter of about 0.6 Kb displays more or less the same activity as that of the full length 1.3 Kb MCKpromoter.

A mutated form of estrogen ligand-binding domain (ERT2) that binds to synthetic antagonists (such as tamoxifen or its derivative 4-hydroxy-tamoxifen) but not to circulating estrogen, was fused to the Cre recombinase (Cre) to create CreERT2 (also known as "inducible Cre"). When tamoxifen binds to CreERT2, it induces a conformational change of CreERT2, leading to its nuclear translocation, followed by Cre/Lox-mediated recombination.