Visualization of PAX7 protein dynamics in muscle satellite cells in a YFP knock-in-mouse line

Background: Satellite cells are residential muscle stem cells that express a paired box protein, PAX7. Results: Here, we report a knock-in mouse line expressing a PAX7-enhanced yellow fluorescent protein (YFP) fusion protein that enables visualization of PAX7 protein dynamics in living satellite cells through YFP fluorescence. The YFP fluorescence signals in Pax7-YFP knock-in mice clearly recapitulated the endogenous expression of PAX7 protein in satellite cells. YFP+ satellite cells were efficiently isolated from muscle tissues by fluorescence-activated cell sorting. Homozygous Pax7-YFP knock-in mice (Pax7YFP/YFP) were viable, grew and regenerated muscle normally, and Pax7YFP/YFP mouse-derived satellite cells proliferated, differentiated, and self-renewed as efficiently as those from wild-type (Pax7+/+) mice. Conclusions: Taken together, our Pax7-YFP mouse line is a useful tool to aid the development of stem-cell-based therapies for muscle diseases