Characterization of Mustn1PRO-GFPtpz transgenic mice

Mustn1 has been characterized as a gene that has very restricted expression to the musculoskeletal system. However, its spatiotemporal expression was not comprehensively depicted in vivo. In this study, we have characterized the promoter of Mustn1 gene, which is mainly regulated by AP-1 family proteins. Subsequently, transgenic mice containing Mustn1 promoter-driven GFP transgene was generated. Mustn1 was found mainly expressed in the satellite cells in the adult mice, with notable expression coming from periosteum, endosteum and endothelium of blood vessels as well. This novel finding indicated that 1) Mustn1 is co-regulated with other common myogenic marker genes such as MyoD and mogenin; 2) Mustn1 is likely involved in the early differentiation of mesoderm due to the common origin of satellite cells and endothelial cells; and 3) Mustn1 is a differentiation marker that is specifically expressed in the musculoskeletal system.