Role of MyoD in denervated, disused, and exercised muscle

Abstract

The myogenic regulatory factor MyoD plays an important role in embryonic and adult skeletal muscle growth. Even though it is best known as a marker for activated satellite cells, it is also expressed in myonuclei, and its expression can be induced by a variety of different conditions. Several model systems have been used to study the mechanisms behind MyoD regulation, such as exercise, stretch, disuse, and denervation. Since MyoD reacts in a highly muscle-specific manner, and its expression varies over time and between species, universally valid predictions and explanations for changes in MyoD expression are not possible. This review explores the complex role of MyoD in muscle plasticity by evaluating the induction of MyoD expression in the context of muscle composition and electrical and mechanical stimulation.

Altered Expression of Myogenic Regulatory Factors in the Mouse Model of Amyotrophic Lateral Sclerosis

“…Discrepancies between MRF transcript and protein levels have also been reported earlier [62,63] . Because of a general lack of simultaneous RNA/protein level studies and a wide variety of techniques and experimental species used, a universally valid MRF response to denervation cannot be stated [64] . However, the fact that Myog transcripts were equally upregulated in denervated and SOD1-G93A muscle, but the MYOG protein increase was only apparent upon denervation, suggests that posttranscriptional regulation of this factor in SOD1-G93A mice may be altered.…”

Myogenic differentiation factor 1 and myogenin expression not elevated in regenerated masticatory muscles of dystrophic (mdx) mice

“…Current muscle research has focused attention on myogenic regulatory factors (MRF) as possible treatment targets for neural myopathies including DMD [11]. MRF MyoD1, for instance, is required for differentiating myoblasts into myocytes, and MRF myogenin for myoblasts to become mature myofibers during embryonic muscle development [4,15].…”

“…MRF MyoD1, for instance, is required for differentiating myoblasts into myocytes, and MRF myogenin for myoblasts to become mature myofibers during embryonic muscle development [4,15]. The function of MyoD1 and myogenin in healthy adult muscle unfortunately is less well understood [4,11,17]. A recent study suggests that myogenin may regulate exercise capacity and skeletal muscle metabolism [4].…”

“…Die aktuelle Muskelforschung hat sich auf die myogenischen Regulierungsfaktoren (MRF) als einen möglichen Ansatzpunkt für die Behandlung von Muskelerkrankungen einschließlich DMD konzentriert [11]. Während der embryonalen Muskelentwicklung werden beispielsweise der Regulierungsfaktor MyoD1 für die Ausdifferenzierung von Myoblasten in Myozyten benö-tigt und der Regulierungsfaktor Myogenin für die Umwandlung der Myoblasten in reife Muskelfaserzellen [4,15].…”

“…Während der embryonalen Muskelentwicklung werden beispielsweise der Regulierungsfaktor MyoD1 für die Ausdifferenzierung von Myoblasten in Myozyten benö-tigt und der Regulierungsfaktor Myogenin für die Umwandlung der Myoblasten in reife Muskelfaserzellen [4,15]. Die Funktion von MyoD1 und Myogenin in gesunden adulten Muskeln ist leider weniger klar [4,11,17]. Einer kürzlich publizierten Studie zufolge könnte Myogenin eine Rolle bei der Steuerung der Leistungsfähigkeit und des Stoffwechsels der Skelettmuskulatur spielen [4].…”