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Paradoxical decrease in myf-5 messenger RNA levels during induction of myogenic differentiation by insulin-like
F J Mangiacapra1, S L Roof, D Z Ewton
1Biology Department, Syracuse University, New York 13244-1220.
Molecular Endocrinology (Baltimore, Md.)
|December 1, 1992
Summary
Insulin-like growth factors (IGFs) are crucial for muscle development. While IGFs initially require myf-5 expression for myogenin induction, subsequent myogenin elevation becomes independent of myf-5.
Area of Science:
- Muscle development and differentiation
- Molecular biology
- Gene regulation
Background:
- Insulin-like growth factors (IGFs) induce myogenesis.
- Myogenin is a key gene in muscle differentiation.
- Myf-5 is another important gene in the MyoD family involved in myogenesis.
Purpose of the Study:
- Investigate the role of myf-5 in IGF-induced myogenesis.
- Understand the regulation of myf-5 during muscle differentiation.
- Determine the relationship between myf-5 and myogenin expression.
Main Methods:
- Studied L6 myoblasts and human muscle myoblasts.
- Utilized low serum medium with IGF-II.
- Employed antisense oligodeoxynucleotides to inhibit myf-5 translation.
- Measured mRNA levels and assessed myogenesis markers (cell fusion, creatine kinase).
Main Results:
- Myf-5 mRNA was present in proliferating myoblasts but decreased significantly with IGF-II treatment.
- Inhibition of myf-5 translation blocked myogenin mRNA increase and myogenesis.
- Myogenin expression elevation became independent of myf-5 after initial induction.
Conclusions:
- Myf-5 expression is essential for the initial induction of myogenin by IGFs.
- Subsequent myogenin elevation is independent of myf-5, potentially via myogenin autoinduction.
- The functional significance of decreased myf-5 mRNA levels during differentiation remains unclear.