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The transcription factor MyoD is required for the skeletal muscle neuromuscular junction development and its deletion increases the slow fibre type proportions postnatally
Author(s) -
Macharia Raymond,
Otto Anthony,
Patel Ketan
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a227-a
Subject(s) - myod , myogenesis , pitx2 , skeletal muscle , myocyte , biology , myogenin , neuromuscular junction , medicine , endocrinology , microbiology and biotechnology , transcription factor , neuroscience , genetics , gene , homeobox
The basic helix loop helix protein MyoD is involved in skeletal muscle differentiation. Gene knock out experiments have shown that MyoD role in the generation of myoblasts is redundant and that MyoD null mouse phenotype rarely shows any histomorphological difference from the wildtype postnatally. However, though not fully addressed, the continuous expression and presence of MyoD in postnatal life may have an important role in muscle fibre type differentiation. Many reports show that the nerve is a determinant of muscle fibre types during secondary myogenesis. However, the cross talk between muscle and nerve subsumes that this is a one way process and that the nerve instructs muscle. The MyoD null mouse model presents a unique model to show whether this muscle development transcription factor instructs the formation and activity of the neuromuscular junction. In our investigation, we compare results of muscle contractile performance by direct (neural) and field stimulation. Results We show that neural stimulation in the MyoD null mouse skeletal muscle is significantly reduced while field stimulation values are similar to those of the wildtype. The muscle fibre type analysis shows that MyoD deletion converts a population of IIa and IIx fibres to slow oxidative type while type IIb remains unchanged. In addition we show that the number of satellite cells is higher in the MyoD null mouse but activation rates of satellite cells in the MyoD null is comparable to that of the wildtype. Conclusion MyoD as a transcription factor is involved in the process of neuromuscular junction development and controls muscle fibre type proportions. This work was supported by the Royal Veterinary College internal grant scheme (IGS‐MAC.VPR‐2004)