Fig. 2.

Foxj3m/m mice have impaired skeletal muscle regeneration. (A) Schematic outlying the Foxj3-β-geo “gene trapped” locus. (B) PCR genotyping of tails from Foxj3 mice. (C) The Foxj3 mutant transcript in Foxj3m/m gastrocnemius cDNA does not encode beyond exon 5 using RT-PCR techniques. Note that the transcript is amplified up to exon 5 in the Foxj3m/m muscle; however, only the wild type transcript can be amplified from exon 6 and beyond. (D) Histological sections of WT (+/+) and Foxj3m/m gastrocnemius skeletal muscle uninjured, 2 weeks, and 3 weeks post-cardiotoxin injury from 3-month-old male littermates. Note that the wild type skeletal muscle is fully regenerated with restoration of skeletal muscle architecture within two weeks (note central nuclei representing regenerated myofibers). Conversely, theFoxj3m/m cardiotoxin injured skeletal muscle fails to fully regenerate up to 3 weeks postinjury. Black arrowheads mark areas of necrosis and adipogenesis that form and replace myofibers following injury in the Foxj3m/m mice.