Fig. 5.

miR-24-3p is essential for skeletal muscle regeneration. A Hmga1 is gradually upregulated in TA muscles on days 1–3 post-injury and downregulated on days 5–14 post-injury. Hmga1 values were normalized to the Rps13 values. B We injected a fluorescence (DyLight594) conjugated Ant-24 into TA muscle of adult mice on day 3 after CTX injury and harvested the samples day 5 post-injury. Ant-24 incorporates into TA muscle, including MuSCs on day 5 post-injury. Arrows indicate a subset of PAX7-positive MuSCs overlapped with Ant-24 fluorescence. C miR-24-3p level was also decreased in the MuSCs isolated from these samples. qRT-PCR was carried out for miR-24-3p, and its values were first normalized to the U6sn values and again relative to NC values. D, E Ant-NC and Ant-24 were injected in TA muscle on day 3 post-injury. The miR-24-3p level was repressed, and Hmga1 and Id3 transcript levels were derepressed in the TA muscle on day 5 post-injury. Hmga1 and Id3 values were normalized to the respective Rps13 values and then again to the Ant-NC values. F–I The miR-24-3p level remained repressed on days 7 and 14 post-injury, and Hmga1 and Id3 transcript levels remained deprepressed in the Ant-24 samples. J Representative images of H&E staining showing that the Ant-24 impairs regeneration on days 7 and 14 post-injury. K, L DESMIN and LAMININ staining and cross-section areas (CSA) of the regenerating fibers on day 14 using the Fiji software. More than 600 fibers were counted from ten random sections of five mice in both groups. Scale bar: 50 μM. Mean ± SD of the samples from five mice. *P < 0.001; **P < 0.01