title: Muscle growth in teleost fish is regulated by factors utilizing the activin II B receptor.
abstract: The activin type IIB receptor (Acvr2b) is the cell surface receptor for multiple transforming growth factor β (TGF-β) superfamily ligands, several of which regulate muscle growth in mammals. To investigate the role of the Acvr2b signaling pathway in the growth and development of skeletal muscle in teleost fish, transgenic rainbow trout (RBT; Oncorhynchus mykiss) expressing a truncated form of the acvr2b-2a (acvr2b(▵)) in muscle tissue were produced. High levels of acvr2b(▵) expression were detected in the majority of P1 transgenic fish. Transgenic P1 trout developed enhanced, localized musculature in both the epaxial and hypaxial regions (dubbed 'six pack'). The F1 transgenic offspring did not exhibit localized muscle growth, but rather developed a uniform body morphology with greater girth, condition factor and increased muscle fiber hypertrophy. There was a high degree of variation in the mass of both P1 and F1 transgenic fish, with several fish of each generation exhibiting enhanced growth compared with other transgenic and control siblings. The 'six pack' phenotype observed in P1 transgenic RBT overexpressing acvr2b(▵) and the presence of F1 individuals with altered muscle morphology provides compelling evidence for the importance of TGF-β signaling molecules in regulating muscle growth in teleost fish.
authors.affiliation: Department of Fisheries, Animal and Veterinary Science, University of Rhode Island, Kingston, RI 02881, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Phelps
authors.forename: Ian M
authors.initials: IM
authors.lastname: Jaffe
authors.forename: Terence M
authors.initials: TM
authors.lastname: Bradley
mesh_terms: D030301:Activin Receptors, Type II / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D030801:Animals, Genetically Modified; D005260:Female; D029941:Fish Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008297:Male; D008969:Molecular Sequence Data; D024510:Muscle Development; D016212:Transforming Growth Factor beta / Q000378:metabolism; D014337:Trout / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism
chemical_list: D029941:Fish Proteins; D016212:Transforming Growth Factor beta; D030301:Activin Receptors, Type II; C425584:activin receptor type II-B
keywords: TGF-β; activin receptor IIB; muscle; myostatin; transgenic; trout