Synthetic muscle creatine kinase 8 enhanced (CK8e) promoter
Synthetic muscle-specific promoter derived from the muscle creatine kinase (MCK/Ckm) enhancer and proximal promoter, with poorly conserved sequence removed to minimize its size. Drives high-level, striated-muscle-restricted expression in skeletal and cardiac muscle, sized to fit large transgenes such as microdystrophin into AAV vectors.
Origin: Synthetic; minimized MCK enhancer/promoter (Hauschka lab CK-cassette series)
Characteristics
Combines a modified murine muscle creatine kinase (MCK/Ckm) enhancer with a modified MCK proximal promoter, with poorly conserved enhancer sequence removed to minimize size while retaining striated-muscle activity. One of the most compact of the Hauschka lab's MCK-based regulatory cassettes, giving muscle-restricted expression suited to packaging within the limited capacity of AAV vectors.
Applications: Muscle-restricted transgene expression in AAV vectors for Duchenne muscular dystrophy gene therapy; used as the promoter driving canine microdystrophin-5 (rAAV9-CK8e-c-uDys5) in a blinded, placebo-controlled systemic AAV9 study in the golden retriever muscular dystrophy (GRMD) dog model, producing dose-dependent microdystrophin protein in skeletal, diaphragm, and cardiac muscle.
Limitations: Drives expression in both skeletal and cardiac muscle rather than restricting to one, so it is not suited where cardiac-only or skeletal-only expression is required. No published head-to-head comparison of CK8e's absolute expression strength against other compact synthetic muscle promoters such as SPc5-12.