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. 2014 Mar 24;9(3):e93140. doi: 10.1371/journal.pone.0093140

Figure 7. Mature miRNAs are required to promote muscle reinnervation.

Figure 7

A tdTomato reporter mouse line was crossed with a mouse expressing Cre recombinase from the Parvalbumin locus. Expression of tdTomato in the EDL, a muscle primarily composed of fast-type muscle fibers, (B) and the soleus, a muscle composed mostly of slow-type muscle fibers (A). tdTomato is also found in axons of proprioceptive sensory neurons (A, arrow), which express Parvalbumin. Scale bar  = 240 μm. (D) NMJs in 1 month-old PV-Cre;Dicer mice are similar to those in control animals (C). (F–H) In PV-Cre-Dicer mice, muscle reinnervation is delayed compared to controls (E, G–H) 7 days post nerve crush. At least 4 mice were examined per genotype and 50 NMJs per mouse visualized. Error bars represent SEM. P-value (*) <0.001. Scale bar  = 20 μm. (I–J) Similarly, deletion of Dicer in mature muscle fibers via electroporation of a plasmid expressing Cre recombinase tagged with GFP also slowed down NMJ regeneration. Error bars represent SEM. Scale bar  = 20 μm.