Generation of a MyoD knock-in reporter mouse line to study muscle stem cell dynamics and heterogeneity
Ryo Fujita,
Seiya Mizuno,
Taketaro Sadahiro,
Takuto Hayashi,
Takehito Sugasawa,
Fumihiro Sugiyama,
Yusuke Ono,
Satoru Takahashi,
Masaki Ieda
Affiliations
Ryo Fujita
Division of Regenerative Medicine, Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan; Department of Cardiology, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan; Corresponding author
Seiya Mizuno
Laboratory Animal Resource Center, Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Taketaro Sadahiro
Department of Cardiology, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Takuto Hayashi
Department of Anatomy and Embryology, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Takehito Sugasawa
Laboratory of Clinical Examination and Sports Medicine, Department of Clinical Medicine, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Fumihiro Sugiyama
Laboratory Animal Resource Center, Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Yusuke Ono
Department of Muscle Development and Regeneration, Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811, Japan
Satoru Takahashi
Laboratory Animal Resource Center, Transborder Medical Research Center, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan; Department of Anatomy and Embryology, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Masaki Ieda
Department of Cardiology, Institute of Medicine, University of Tsukuba, Ibaraki 305-8575, Japan
Summary: Myoblast determination protein 1 (MyoD) dynamics define the activation status of muscle stem cells (MuSCs), aiding in muscle tissue regeneration after injury. However, the lack of experimental platforms to monitor MyoD dynamics in vitro and in vivo has hampered the investigation of fate determination and heterogeneity of MuSCs. Herein, we report a MyoD knock-in (MyoD-KI) reporter mouse expressing tdTomato at the endogenous MyoD locus. Expression of tdTomato in MyoD-KI mice recapitulated the endogenous MyoD expression dynamics in vitro and during the early phase of regeneration in vivo. Additionally, we showed that tdTomato fluorescence intensity defines MuSC activation status without immunostaining. Based on these features, we developed a high-throughput screening system to assess the effects of drugs on the behavior of MuSCs in vitro. Thus, MyoD-KI mice are an invaluable resource for studying the dynamics of MuSCs, including their fate decisions and heterogeneity, and for drug screening in stem cell therapy.
