title: Molecular characterization of the MuRF genes in rainbow trout: Potential role in muscle degradation.
abstract: Muscle growth is determined primarily by the balance between protein synthesis and degradation. When rates of protein synthesis are similar between individuals, protein degradation is critical in explaining differences in growth efficiency. Studies in mammals showed that muscle atrophy results from increased protein breakdown, and is associated with activation of the ubiquitin proteasome pathway, including induction of the muscle-specific ubiquitin protein ligase, MuRF1. Animals lacking MuRF1 are resistant to muscle atrophy. In fish, little is known about the role of the proteasome/MuRF pathway in muscle degradation. The objectives of this study were to: 1) clone and characterize MuRF genes in rainbow trout; and 2) determine expression of MuRF genes in association with starvation- and vitellogenesis-induced muscle atrophy in rainbow trout. We have identified full-length cDNA sequences for three MuRF genes (MuRF1, MuRF2, and MuRF3). These genes encode proteins with typical MuRF structural domains, including a RING-finger, a B-box and a Leucine-rich coiled-coil domain. RT-PCR analysis showed that MuRF genes are predominantly expressed in muscle and heart tissues. Real time PCR analysis revealed that expression of all MuRF genes is up-regulated during starvation and MuRF3 is up-regulated in vitellogenesis-associated muscle degradation. These results suggest that MuRF genes have an important role in fish muscle protein degradation. Further studies are warranted to assess the potential use of MuRF genes as tools to monitor fish muscle growth and degradation.
authors.affiliation: Laboratory of Animal Biotechnology and Genomics, Division of Animal and Nutritional Sciences, West Virginia University, Morgantown, WV 26506, USA.
authors.forename: Jiannan
authors.initials: J
authors.lastname: Wang
authors.forename: Mohamed
authors.initials: M
authors.lastname: Salem
authors.forename: Nan
authors.initials: N
authors.lastname: Qi
authors.forename: P Brett
authors.initials: PB
authors.lastname: Kenney
authors.forename: Caird E
authors.initials: CE
authors.lastname: Rexroad
authors.forename: Jianbo
authors.initials: J
authors.lastname: Yao
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D029941:Fish Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D005508:Food Deprivation; D015870:Gene Expression; D008969:Molecular Sequence Data; D009124:Muscle Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D009133:Muscular Atrophy / Q000209:etiology / Q000235:genetics / Q000378:metabolism; D017686:Oncorhynchus mykiss / Q000196:embryology / Q000235:genetics / Q000378:metabolism*; D010802:Phylogeny; D012333:RNA, Messenger / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution; D044767:Ubiquitin-Protein Ligases / Q000145:classification / Q000235:genetics / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D009124:Muscle Proteins; D012333:RNA, Messenger; D044767:Ubiquitin-Protein Ligases