The Obestatin/GPR39 System Is Up-regulated by Muscle Injury and Functions as an Autocrine Regenerative System

• Published in: The Journal of biological chemistry Vol. 287; no. 45; pp. 38379 - 38389
• Main Authors: Gurriarán-Rodríguez, Uxía, Santos-Zas, Icía, Al-Massadi, Omar, Mosteiro, Carlos S., Beiroa, Daniel, Nogueiras, Rubén, Crujeiras, Ana B., Seoane, Luisa M., Señarís, José, García-Caballero, Tomás, Gallego, Rosalía, Casanueva, Felipe F., Pazos, Yolanda, Camiña, Jesús P.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 02-11-2012; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Autocrine Communication; Cardiotoxins - toxicity; Cell Biology; Cell Differentiation; Cell Differentiation - drug effects; Cell Differentiation - genetics; Cell Line; Gene Expression - drug effects; Ghrelin - genetics; Ghrelin - metabolism; Ghrelin - pharmacology; Immunoblotting; Immunohistochemistry; Male; Muscle; Muscle Regeneration; Muscle, Skeletal - injuries; Muscle, Skeletal - metabolism; Muscle, Skeletal - physiopathology; Muscular Diseases - chemically induced; Muscular Diseases - pathology; Muscular Diseases - physiopathology; Myoblasts, Skeletal - cytology; Myoblasts, Skeletal - drug effects; Myoblasts, Skeletal - metabolism; MyoD Protein - genetics; MyoD Protein - metabolism; Myogenesis; Myogenin - genetics; Myogenin - metabolism; Rats; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled - genetics; Receptors, G-Protein-Coupled - metabolism; Regeneration; Reverse Transcriptase Polymerase Chain Reaction; RNA Interference; Signal Transduction; Up-Regulation; Cell Differentiation; Muscle; Muscle Regeneration; Myogenesis; Cell Biology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M112.374926

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.
Background: Satellite cell activation is orchestrated by several signals, which induce their differentiation into skeletal muscle fibers.
Results: Obestatin and the GPR39 receptor exert an autocrine role on the control of myogenesis.
Conclusion: Our data indicate that obestatin/GPR39 is an injury-regulated signal that functions as a myogenic regenerative system.
Significance: Strategies to enhance obestatin-mediated signaling could be useful in treating trauma-induced muscle injuries and skeletal muscle myopathies.