Fig. 2From: Fragile X mental retardation protein regulates skeletal muscle stem cell activity by regulating the stability of Myf5 mRNAFMRP is required for efficient priming of muscle stem cells to rapidly activate the myogenic program, self-renewal, and differentiation. a Fraction of PAX7(+) satellite cells accumulating MYF5 (left) and MYOD (right) after 1 h culture of single EDL myofibers. b Representative immunostaining of PAX7 (green) and MYOD (red) on single EDL myofibers isolated from adult wild-type and Fmr1 −/− mice after 48 h culture. c Numbers of satellite cells undergoing self-renewal (PAX7+MYOD−), activating the myogenic program (PAX7+MYOD+) and differentiating (PAX7−MYOD+) on single EDL myofibers isolated from adult wild-type (white) and Fmr1 −/− (gray) mice after 2-day culture. d Levels of MyoD, Myog, and Myh3 transcripts, relative to Actb, in satellite cells isolated from adult muscle of wild-type (wt, black) and Fmr1 −/− (gray) mice, after 4-day culture. e Levels of MYOG protein, relative to ACTB, from cell lysates of 4-day cultured satellite cells isolated from muscle of wt (black) and Fmr1 −/− (white) mice. Representative immunoblot is shown. MYOG levels are calculated by densitometry of three immunoblots. f Levels of Pax7 and Myf5 transcripts, relative to Actb, in satellite cells isolated from adult muscle of wild-type (wt, black) and Fmr1 −/− (gray) mice, 2 days after ctx injury. g Representative images of EdU(+) MyoD(+) satellite cells present on transverse sections of TA muscle, 3 days after ctx injury. White arrows indicate MYOD(+) EdU(+) satellite cells. Scale bar, 50 μm. h Fraction of MYOD(+) satellite cells that are EdU(+), as indicated in g. All values indicate mean (n ≥ 3) ± s.e.m. *p < 0.05, ***p < 0.001Back to article page