Maine Medical Center, Medical Education, Maine Medical Center Research Institute, Center for Molecular Medicine
Muscle Fibers, Skeletal, Wound Healing, Stem Cells
Purpose/Background: CTHRC1 is a secreted protein highly induced in tissues undergoing repair and remodeling. Osteogenic differentiation of osteoblasts in vitro revealed that endogenously expressed CTHRC1 promotes bone formation by affecting both proliferation and differentiation. Our recent study demonstrated that CTHRC1 also inhibits osteoclastogenic differentiation, thereby playing a key role in balancing bone formation with bone resorption in vivo. However, its function on skeletal muscle stem cell and skeletal muscle regeneration is still remains unknown.
Methods/Approach: In vitro culture of skeletal muscle stem cell isolated from wildtype and Cthrc1 mutant mice. Western blotting, Immuno-histological staining, Flow cytometry analysis, and RT-PCR assay are conducted.
Results: Cthrc1 is transiently expressed in regenerating muscle with peak expression seen 7 days after injury. In primary cultured satellite cells, Cthrc1 is expressed in activated proliferating cells, and dramatically decreased under myogenic differentiation conditions. Comparing satellite cells isolated from Cthrc1 mutant and wildtype mice, there is no cell autonomous effect on cell proliferation (as determined by Ki67 immunofluorescence staining and EdU incorporation). Flow cytometric data showing that cell cycle progression is not affected by CTHRC1. Cthrc1 mutant cells differentiate more rapidly than wildtype cells under myogenic differentiation condition, which is supported by a significant down-regulation of myogenic determination factors, MyoD1 and myogenin, at both protein and mRNA level. In the cardiotoxin-induced muscle injury model, Cthrc1 impacted the time course of regeneration with myofiber size being increased in skeletal muscle of Cthrc1 mutant mice 10 days after injury; however, the final regenerated muscle size was significantly smaller in mutant mice 61 days after injury.
Conclusions: Collectively our data indicate that Cthrc1 functions as a negative regulator on myogenic differentiation in vitro, and it is essential for successful regeneration of injured skeletal muscle.
Jin, Yong-Ri; Wang, Qiaozeng; Prudovsky, Igor; and Lindner, Volkhard, "Functional study of CTHRC1 on skeletal muscle regeneration and skeletal muscle stem cells" (2020). Costas T. Lambrew Research Retreat 2020. 46.