Myokine BDNF highly expressed in Type I fibers inhibits the differentiation of myotubes into Type II fibers

Abstract

Background Myofibers are broadly classified as slow-twitch (Type I) and fast-twitch (Type II) fibers. These two types of myofibers coexist within the same skeletal muscle tissue, determining the contractile and metabolic properties of skeletal muscle tissue by fiber type distribution. Methods and results By examining each fiber type separately, we confirmed that brain-derived neurotrophic factor (BDNF) gene is highly expressed in Type I fibers. When exposed to BDNF, primary myotubes exhibited reduced expression of Myosin Heavy Chain (MyHC) II, a marker protein characteristic of Type II fibers. BDNF overexpression in regenerating muscle tissue led to a decrease in the distribution of Type IIA fibers. Conclusions We suggest that BDNF highly expressed in Type I fibers downregulates MyHC II expression in myotubes, eventually inhibiting Type IIA fiber generation.

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