Myonucleus-related properties in soleus muscle fibers of mdx mice

Masahiro Terada, Yong Bo Lan, Fuminori Kawano, Takashi Ohira, Yoko Higo, Naoya Nakai, Kazuhiko Imaizumi, Akihiko Ogura, Norihiro Nishimoto, Yasuo Adachi, Yoshinobu Ohira

    Research output: Contribution to journalArticlepeer-review

    8 Citations (Scopus)

    Abstract

    Distribution and total number of myonuclei in single soleus muscle fibers, sampled from tendon to tendon, were analyzed in mdx and wild-type (WT) mice. Apoptotic myonuclei and the microscopic structure around the myonuclei were also analyzed. Three types of muscle fibers of mdx mice with myonuclear distribution at either central, peripheral, or both central and peripheral regions were observed in the longitudinal analyses. All of the myonuclei were located at the peripheral region in WT mice. The total number of myonuclei counted in the whole length of fibers with peripheral myonuclei only was 17% less in mdx than in WT mice (p < 0.05). But the total myonuclear numbers in mdx mouse fibers with different distribution (peripheral vs. central) of myonuclei were identical, and the peripheral nucleus was noted where the central nucleus was missing. Myonuclei located between the center and peripheral regions were also seen in the cross-sectional analyses of muscle fibers. The cross-sectional area and length of fibers, sarcomere number, myonuclear size, myosin heavy chain expression, satellite cell number and neuromuscular junction were identical between each type of fiber. Apoptosis was not detected in any myonuclei located either in central or peripheral regions of muscle fibers. Thus, it was suggested that apoptosis-related loss of central myonuclei and regeneration-related new accretion at the peripheral region is not the cause of different distribution of myonuclei seen in muscle fibers in mdx mice. However, it was speculated that cross-sectional migration of myonuclei from central to peripheral regions may be induced in response to regeneration, because the total myonuclear numbers in fibers with different distribution of myonuclei were identical, and the peripheral nucleus was noted where the central nucleus was missing. Further, myonuclei located between the center and peripheral regions were also seen. However, the question remains as to how or why nuclei might migrate to the periphery in a regenerating muscle fiber, since there was no microscopic evidence of any structural changes around the myonuclei that may be responsible for the movement of the nucleus.

    Original languageEnglish
    Pages (from-to)248-259
    Number of pages12
    JournalCells Tissues Organs
    Volume191
    Issue number3
    DOIs
    Publication statusPublished - 2010 Feb

    Keywords

    • Apoptosis
    • Central and/or peripheral myonuclei
    • mdx mice
    • Soleus muscle fibers

    ASJC Scopus subject areas

    • Anatomy
    • Histology
    • Medicine(all)

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