title: Sox6 is required for normal fiber type differentiation of fetal skeletal muscle in mice.
abstract: Sox6, a member of the Sox family of transcription factors, is highly expressed in skeletal muscle. Despite its abundant expression, the role of Sox6 in muscle development is not well understood. We hypothesize that, in fetal muscle, Sox6 functions as a repressor of slow fiber type-specific genes. In the wild-type mouse, differentiation of fast and slow fibers becomes apparent during late fetal stages (after approximately embryonic day 16). However, in the Sox6 null-p(100H) mutant mouse, all fetal muscle fibers maintain slow fiber characteristics, as evidenced by expression of the slow myosin heavy chain MyHC-beta. Knockdown of Sox6 expression in wild-type myotubes results in a significant increase in MyHC-beta expression, supporting our hypothesis. Analysis of the MyHC-beta promoter revealed a Sox consensus sequence that likely functions as a negative cis-regulatory element. Together, our results suggest that Sox6 plays a critical role in the fiber type differentiation of fetal skeletal muscle.
authors.affiliation: University of California, Davis, Division of Cardiovascular Medicine/Rowe Program in Human Genetics, Davis, California 95616, USA. nhagiwara@ucdavis.edu
authors.forename: Nobuko
authors.initials: N
authors.lastname: Hagiwara
authors.forename: Michael
authors.initials: M
authors.lastname: Yeh
authors.forename: Ann
authors.initials: A
authors.lastname: Liu
mesh_terms: D000818:Animals; D004268:DNA-Binding Proteins / Q000235:genetics / Q000502:physiology*; D004628:Embryonic Structures; D005786:Gene Expression Regulation; D018507:Gene Expression Regulation, Developmental; D006609:High Mobility Group Proteins / Q000235:genetics / Q000502:physiology*; D051379:Mice; D018485:Muscle Fibers, Skeletal / Q000166:cytology* / Q000378:metabolism; D018482:Muscle, Skeletal / Q000196:embryology* / Q000254:growth & development; D018995:Myosin Heavy Chains / Q000235:genetics*; D011401:Promoter Regions, Genetic / Q000235:genetics; D050436:Regulatory Elements, Transcriptional; D055755:SOXD Transcription Factors; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*
chemical_list: D004268:DNA-Binding Proteins; D006609:High Mobility Group Proteins; D055755:SOXD Transcription Factors; C095939:Sox6 protein, mouse; D014157:Transcription Factors; D018995:Myosin Heavy Chains