title: IGF-I and IGF-II effects on local IGF system and signaling pathways in gilthead sea bream (Sparus aurata) cultured myocytes.
abstract: The insulin-like growth factors (IGFs) have a fundamental role in a vast range of functions acting through a tyrosine-kinase receptor (IGF-IR). IGFs in muscle can affect the expression of components of the local IGF system, myogenic regulatory factors (MRFs), proliferating (proliferating cell nuclear antigen, PCNA) or differentiating molecules (myosin heavy chain, MHC) and, lead to the activation of different signaling pathways. The response of all these genes to IGFs incubation at two different times in day 4 cultured myocytes of gilthead sea bream was analyzed. Both IGFs increased the expression of IGF-I and IGFBP-5, but showed different effects on the receptors, with IGF-I suppressing the expression of both isoforms (IGF-IRa and IGF-IRb) and IGF-II up-regulating only IGF-IRb. Moreover, the protein levels of PCNA and target of rapamycin (TOR) increased after IGF-II incubation, although a decline in Myf5 and a rise in MHC gene expression was caused by IGF-I. Taken together, these results provide evidence for the importance of IGFs on controlling muscle development and growth in gilthead sea bream and suggest that each IGF may be preferentially acting through a specific IGF-IR. Moreover, the data support the hypothesis that IGF-II has a more important role during proliferation, whereas IGF-I seems to be relevant for the differentiation phase of myogenesis.
authors.affiliation: Department of Fisheries Sciences, Faculty of Natural Resources, University of Tehran, Karaj, Iran; Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Sheida
authors.initials: S
authors.lastname: Azizi
authors.affiliation: Department of Fisheries Sciences, Faculty of Natural Resources, University of Tehran, Karaj, Iran. Electronic address: malahi@ut.ac.ir.
authors.forename: Mohammad Ali
authors.initials: MA
authors.lastname: Nematollahi
authors.affiliation: Department of Fisheries Sciences, Faculty of Natural Resources, University of Tehran, Karaj, Iran.
authors.forename: Bagher
authors.initials: B
authors.lastname: Mojazi Amiri
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Vélez
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Cristina
authors.initials: C
authors.lastname: Salmerón
authors.affiliation: Departments of Biochemistry, and Molecular Biology and Medicine, The Howard Hughes Medical Institute, University of Chicago, Chicago, IL 60637, USA.
authors.forename: Shu Jin
authors.initials: SJ
authors.lastname: Chan
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Isabel
authors.initials: I
authors.lastname: Navarro
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Encarnación
authors.initials: E
authors.lastname: Capilla
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Universitat de Barcelona, 08028 Barcelona, Spain. Electronic address: jgutierrez@ub.edu.
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gutiérrez
mesh_terms: D000818:Animals; D018975:Insulin-Like Growth Factor Binding Protein 5 / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000378:metabolism*; D032342:Muscle Cells / Q000378:metabolism*; D021541:Sea Bream / Q000378:metabolism; D015398:Signal Transduction
chemical_list: D018975:Insulin-Like Growth Factor Binding Protein 5; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II
keywords: IGF binding proteins; IGF-I receptors; Insulin-like growth factors; Myogenic regulatory factors; Primary cell cultures; TOR