Mdx mice, which lack dystrophin, were examined for changes in the properties of muscle fibers in the growth process of the masseter muscle at the morphological, protein and transcriptional levels. The slow-type isoform, MyHC-1, and the fast-type isoforms, MyHC-2a, MyHC-2d and MyHC-2b, were examined at the protein and the transcriptional level. Morphological examination showed that in the mdx mouse masseter muscle, degeneration, necrosis, and regeneration occurred, particularly at the age of 4 weeks, and many regenerated muscle fibers with centrally located nuclei were observed at the age of 9 weeks. The results of examination at the protein and the transcriptional level showed that in the process of muscle fiber degeneration, necrosis, and regeneration, the mdx mouse masseter muscle acquires muscle fiber characteristics entirely different from those in the normal mouse masseter muscle. In particular, MyHC-1, which is rarely found in normal mice, was very strongly expressed.
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Acknowledgements This study was supported by grants-in-aid for scientific research (14704046: S.A.) from the Ministry of Education, Culture, Sports, Science and Technology, Japan.
All Science Journal Classification (ASJC) codes
- Cell Biology