Fig. 2

Dynamics of Fmrp and Dcp1a granules in quiescent and activated MuSCs on isolated single muscle fibers. a–c Immunofluorescence analysis of Dcp1a and Fmrp in freshly isolated EDL myofibers (0 h) and at 12, 24, and 48 h of culture. MuSCs are marked with Pax7-nGFP. a Fmrp puncta are evident in quiescent MuSCs at 0 h of culture, and become dispersed at 24 h, whereas Dcp1a puncta are not evident until 24 h of activation. The patterns of staining are consistent with reciprocal patterns of Dcp1a and Fmrp assembly into granules. b The pattern of Dcp1a in proliferating MuSCs (Pax7-nGFP⁺EdU⁺) confirms the timing of MuSC activation. Dcp1a puncta are not observed in quiescent Pax7⁺EdU^- cells, but are present in activated Pax7⁺EdU⁺ MuSC at 24 and 48 h. c By contrast to Dcp1a, the pattern of Fmrp is punctate in quiescent MuSC (Pax7⁺EdU^-) and becomes diffuse in activated Pax7⁺EdU⁺ MuSC at 24 and 48 h. Immunofluorescence was performed in N = 3 biological replicates using > 5 EDL fibers for each combination of antibodies in each assay. Scale bars are 10 μm, or 4.8 μm in magnified panels.