title: The obestatin/GPR39 system is up-regulated by muscle injury and functions as an autocrine regenerative system.
abstract: The maintenance and repair of skeletal muscle are attributable to an elaborate interaction between extrinsic and intrinsic regulatory signals that regulate the myogenic process. In the present work, we showed that obestatin, a 23-amino acid peptide encoded by the ghrelin gene, and the GPR39 receptor are expressed in rat skeletal muscle and are up-regulated upon experimental injury. To define their roles in muscle regeneration, L6E9 cells were used to perform in vitro assays. For the in vivo assays, skeletal muscle tissue was obtained from male rats and maintained under continuous subcutaneous infusion of obestatin. In differentiating L6E9 cells, preproghrelin expression and correspondingly obestatin increased during myogenesis being sustained throughout terminal differentiation. Autocrine action was demonstrated by neutralization of the endogenous obestatin secreted by differentiating L6E9 cells using a specific anti-obestatin antibody. Knockdown experiments by preproghrelin siRNA confirmed the contribution of obestatin to the myogenic program. Furthermore, GPR39 siRNA reduced obestatin action and myogenic differentiation. Exogenous obestatin stimulation was also shown to regulate myoblast migration and proliferation. Furthermore, the addition of obestatin to the differentiation medium increased myogenic differentiation of L6E9 cells. The relevance of the actions of obestatin was confirmed in vivo by the up-regulation of Pax-7, MyoD, Myf5, Myf6, myogenin, and myosin heavy chain (MHC) in obestatin-infused rats when compared with saline-infused rats. These data elucidate a novel mechanism whereby the obestatin/GPR39 system is coordinately regulated as part of the myogenic program and operates as an autocrine signal regulating skeletal myogenesis.
authors.affiliation: Área de Endocrinología Molecular y Celular, Instituto de Investigación Sanitaria de Santiago (IDIS), Santiago de Compostela, Spain.
authors.forename: Uxía
authors.initials: U
authors.lastname: Gurriarán-Rodríguez
authors.forename: Icía
authors.initials: I
authors.lastname: Santos-Zas
authors.forename: Omar
authors.initials: O
authors.lastname: Al-Massadi
authors.forename: Carlos S
authors.initials: CS
authors.lastname: Mosteiro
authors.forename: Daniel
authors.initials: D
authors.lastname: Beiroa
authors.forename: Rubén
authors.initials: R
authors.lastname: Nogueiras
authors.forename: Ana B
authors.initials: AB
authors.lastname: Crujeiras
authors.forename: Luisa M
authors.initials: LM
authors.lastname: Seoane
authors.forename: José
authors.initials: J
authors.lastname: Señarís
authors.forename: Tomás
authors.initials: T
authors.lastname: García-Caballero
authors.forename: Rosalía
authors.initials: R
authors.lastname: Gallego
authors.forename: Felipe F
authors.initials: FF
authors.lastname: Casanueva
authors.forename: Yolanda
authors.initials: Y
authors.lastname: Pazos
authors.forename: Jesús P
authors.initials: JP
authors.lastname: Camiña
mesh_terms: D000818:Animals; D019898:Autocrine Communication; D054715:Cardiotoxins / Q000633:toxicity; D002454:Cell Differentiation / Q000187:drug effects / Q000235:genetics; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects; D054439:Ghrelin / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D015151:Immunoblotting; D007150:Immunohistochemistry; D008297:Male; D018482:Muscle, Skeletal / Q000293:injuries / Q000378:metabolism* / Q000503:physiopathology; D009135:Muscular Diseases / Q000139:chemically induced / Q000473:pathology / Q000503:physiopathology; D017570:MyoD Protein / Q000235:genetics / Q000378:metabolism; D032448:Myoblasts, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D018008:Myogenin / Q000235:genetics / Q000378:metabolism; D034622:RNA Interference; D051381:Rats; D017207:Rats, Sprague-Dawley; D043562:Receptors, G-Protein-Coupled / Q000235:genetics / Q000378:metabolism*; D012038:Regeneration; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D015854:Up-Regulation
chemical_list: D054715:Cardiotoxins; C535178:GPR39 protein, rat; D054439:Ghrelin; D017570:MyoD Protein; D018008:Myogenin; D043562:Receptors, G-Protein-Coupled