title: Musculin isoforms and repression of MyoD in muscle regeneration.
abstract: We studied possible negative regulators of MyoD using a 27 time point muscle regeneration series in vivo and identified Musculin as a key candidate for transcriptional repression of MyoD. Characterization of Musculin proteins showed two isoforms: the previously characterized 201 aa protein (1a) and a novel 180 aa isoform (1b). We show that the Musculin 1b isoform is equally effective at blocking MyoD-induced transcription as the 1a isoform. Our data narrow the likely repressor domain to between position 158 and 173 in the Musculin protein sequence, and suggest that the induction of Musculin is responsible for the rapid down-regulation of MyoD at 4-5 days during staged regeneration.
authors.affiliation: Research Center for Genetic Medicine, Children's National Medical Center, Washington, DC 20010, USA.
authors.forename: Po
authors.initials: P
authors.lastname: Zhao
authors.forename: Eric P
authors.initials: EP
authors.lastname: Hoffman
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D051792:Basic Helix-Loop-Helix Proteins; D015536:Down-Regulation; D051379:Mice; D008969:Molecular Sequence Data; D009132:Muscles / Q000502:physiology*; D017570:MyoD Protein / Q000096:biosynthesis / Q000235:genetics*; D018008:Myogenin / Q000235:genetics; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012038:Regeneration / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013997:Time Factors; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics
chemical_list: D051792:Basic Helix-Loop-Helix Proteins; D017570:MyoD Protein; D018008:Myogenin; D020033:Protein Isoforms; D012333:RNA, Messenger; D014157:Transcription Factors; C117673:Msc protein, mouse; C503801:Myog protein, mouse