title: Insulin-like growth factors effects on the expression of myogenic regulatory factors in gilthead sea bream muscle cells.
abstract: Gilthead sea bream (Sparus aurata) is a widely cultured fish; however, muscle development regulation is poorly known. Myogenesis can be activated by the myogenic regulatory factors (MRFs: MyoD, Myf5, myogenin and MRF4) and by endocrine signals from the growth hormone (GH)/insulin-like growth factors (IGFs) axis. We cultured gilthead sea bream myocytes to better understand the role of IGFs in muscle growth and differentiation through the regulation of MRFs expression. First, we studied the expression pattern during culture development of IGFs and IGF-I splice variants. The expression of igf-II was highest at the beginning of the culture and decreased when the cells started to differentiate, similarly to that observed for total igf-I. Igf-Ib showed a paralleled expression pattern as that of total igf-I, whereas igf-Ic was more stable during culture progression. Next, we analyzed the expression of IGFs and MRFs after incubation of cells at day 4 with GH, IGF-I, IGF-II and combinations of them at 3, 6 and 18 h. IGF-II increased myod2 and myf5 expression, genes involved in early muscle cell proliferation. Moreover, IGF-I caused an increase on mrf4 and myogenin expression, both involved in the later stages of development corresponding to differentiation. Regarding the regulation of IGFs expression, igf-I was stimulated by GH and IGF-II alone and combined, whereas igf-II expression was increased in response to IGF-I, suggesting a nice model of crossed regulation. Overall, the present model could be very useful to understand the different regulatory roles of these endocrine and transcription factors on fish myogenesis.
authors.affiliation: Departament de Fisiologia i Immunologia, Facultat de Biologia, Barcelona Knowledge Campus, Universitat de Barcelona, 08028 Barcelona, Spain.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Jiménez-Amilburu
authors.forename: Cristina
authors.initials: C
authors.lastname: Salmerón
authors.forename: Marta
authors.initials: M
authors.lastname: Codina
authors.forename: Isabel
authors.initials: I
authors.lastname: Navarro
authors.forename: Encarnación
authors.initials: E
authors.lastname: Capilla
authors.forename: Joaquim
authors.initials: J
authors.lastname: Gutiérrez
mesh_terms: D000818:Animals; D029941:Fish Proteins / Q000235:genetics / Q000378:metabolism; D013006:Growth Hormone / Q000235:genetics / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism; D032342:Muscle Cells / Q000378:metabolism*; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D051787:Myogenic Regulatory Factor 5 / Q000235:genetics / Q000378:metabolism; D018006:Myogenic Regulatory Factors / Q000235:genetics / Q000378:metabolism*; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D021541:Sea Bream / Q000235:genetics / Q000378:metabolism*; D013002:Somatomedins / Q000235:genetics / Q000378:metabolism*
chemical_list: D029941:Fish Proteins; D017570:MyoD Protein; D051787:Myogenic Regulatory Factor 5; D018006:Myogenic Regulatory Factors; D018008:Myogenin; D013002:Somatomedins; C063403:myogenic factor 6; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone