title: Differential expression of equine myosin heavy-chain mRNA and protein isoforms in a limb muscle.
abstract: The horse is one of the few animals kept and bred for its athletic performance and is therefore an interesting model for human sports performance. The regulation of the development of equine locomotion in the first year of life, and the influence of early training on later performance, are largely unknown. The major structural protein in skeletal muscle, myosin heavy-chain (MyHC), is believed to be primarily transcriptionally controlled. To investigate the expression of the MyHC genes at the transcriptional level, we isolated cDNAs encoding the equine MyHC isoforms type 1 (slow), type 2a (fast oxidative), and type 2d/x (fast glycolytic). cDNAs encoding the 2b gene were not identified. The mRNA expression was compared to the protein expression on a fiber-to-fiber basis using in situ hybridization (non-radioactive) and immunohistochemistry. Marked differences were detected between the expression of MyHC transcripts and MyHC protein isoforms in adult equine gluteus medius muscle. Mismatches were primarily due to the presence of hybrid fibers expressing two fast (2ad) MyHC protein isoforms, but only one fast (mainly 2a) MyHC RNA isoform. This discrepancy was most likely not due to differential mRNA expression of myonuclei.
authors.affiliation: Department of Pathobiology, Division of Anatomy, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands. c.g.h.eizema@vet.uu.nl
authors.forename: Karin
authors.initials: K
authors.lastname: Eizema
authors.forename: Maarten
authors.initials: M
authors.lastname: van den Burg
authors.forename: Arpna
authors.initials: A
authors.lastname: Kiri
authors.forename: Elizabeth G
authors.initials: EG
authors.lastname: Dingboom
authors.forename: Hans
authors.initials: H
authors.lastname: van Oudheusden
authors.forename: Geoffrey
authors.initials: G
authors.lastname: Goldspink
authors.forename: Wim A
authors.initials: WA
authors.lastname: Weijs
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D005121:Extremities; D006736:Horses; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D008969:Molecular Sequence Data; D018485:Muscle Fibers, Skeletal / Q000378:metabolism; D018482:Muscle, Skeletal / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000235:genetics / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D024744:Skeletal Muscle Myosins / Q000235:genetics / Q000378:metabolism*
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D024744:Skeletal Muscle Myosins; D018995:Myosin Heavy Chains