title: Differential regulation of MyoD and myogenin mRNA levels by nerve induced muscle activity.
abstract: The levels of mRNAs coding for the myogenic factors MyoD and myogenin were measured during synapse formation in developing muscle and in adult muscle, after denervation and reinnervation and after muscle paralysis induced by blocking of neuromuscular transmission by neurotoxins known to alter the density and localization of synaptic proteins such as the acetylcholine receptor (AChR). The mRNA levels of both factors depend on usage of the neuromuscular synapses, but they change to different extents. Myogenin mRNA levels decrease drastically with innervation and increase strongly following blocking of transmission whereas the level of MyoD mRNA showed only a small decrease in response to innervation, denervation or muscle paralysis by neurotoxins. Neither mRNA showed a synapse-related cellular distribution. The results suggest that nerve-induced electrical muscle activity determines the cellular ratio of MyoD and myogenin mRNAs in adult muscle.
authors.affiliation: Max-Planck-Institut für medizinische Forschung, Abteilung Zellphysiologie, Heidelberg, Germany.
authors.forename: V
authors.initials: V
authors.lastname: Witzemann
authors.forename: B
authors.initials: B
authors.lastname: Sakmann
mesh_terms: D000367:Age Factors; D000818:Animals; D015152:Blotting, Northern; D001905:Botulinum Toxins / Q000494:pharmacology; D002451:Cell Compartmentation; D005786:Gene Expression Regulation / Q000187:drug effects; D009121:Muscle Denervation; D009124:Muscle Proteins / Q000235:genetics*; D009132:Muscles / Q000502:physiology*; D017570:MyoD Protein; D018008:Myogenin; D009469:Neuromuscular Junction / Q000502:physiology*; D009687:Nuclear Proteins / Q000235:genetics*; D010750:Phosphoproteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D013779:Tetrodotoxin / Q000494:pharmacology
chemical_list: D009124:Muscle Proteins; D017570:MyoD Protein; C057363:MyoD1 myogenic differentiation protein; C503803:Myog protein, rat; D018008:Myogenin; D009687:Nuclear Proteins; D010750:Phosphoproteins; D012333:RNA, Messenger; D013779:Tetrodotoxin; D001905:Botulinum Toxins