title: CCN family protein 2 (CCN2) promotes the early differentiation, but inhibits the terminal differentiation of skeletal myoblasts.
abstract: Many studies have reported that CCN family protein 2 (also known as connective tissue growth factor) induces fibrotic response in skeletal muscle, thus emphasizing the pathological role of CCN2 in muscle tissues. However, the physiological role of CCN2 in myogenesis is still unknown. This study clarified the CCN2 functions during myogenesis. Recombinant CCN2 (rCCN2) promoted proliferation and MyoD production in C2C12 cells and primary myoblasts, but inhibited myogenin production. In accordance with these findings, the gene expression levels of myosin heavy chain, which is a marker of terminally differentiated myoblasts and desmin, which is the main intermediate filament protein of muscle cells, were decreased by rCCN2 treatment. In vivo analyses with Ccn2-deficient skeletal muscle revealed decreased proliferating cell nuclear antigen (PCNA)/MyoD double positive cells and muscle hypoplasia. Consistent with this finding, myogenic marker genes and myotube formation were repressed in Ccn2-deficient myoblasts. The protein production of CCN2 was increased in C2C12 myoblasts treated with tumor necrosis factor-α, which is a pro-inflammatory cytokine, suggesting its role in muscle regeneration after inflammation. These findings indicate that CCN2 promotes proliferation and early differentiation but inhibits the terminal differentiation of myoblasts, thus suggesting that CCN2 plays a physiological role in myogenesis.
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA tnishida@md.okayama-u.ac.jp.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nishida
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Kubota
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Eriko
authors.initials: E
authors.lastname: Aoyama
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Danilo
authors.initials: D
authors.lastname: Janune
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Lyons
authors.affiliation: Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA Department of Biochemistry and Molecular Dentistry, Okayama University Graduate School of Medicine, Dentistry, and Pharmaceutical Sciences, Okayama 700-8525, Japan; Advanced Research Center for Oral and Craniofacial Sciences, Okayama University Dental School, Okayama 700-8525, Japan; and Department of Orthopaedic Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA takigawa@md.okayama-u.ac.jp.
authors.forename: Masaharu
authors.initials: M
authors.lastname: Takigawa
mesh_terms: D002454:Cell Differentiation / Q000235:genetics*; D055513:Connective Tissue Growth Factor / Q000235:genetics / Q000378:metabolism*; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D024510:Muscle Development / Q000235:genetics*; D018482:Muscle, Skeletal / Q000254:growth & development / Q000378:metabolism; D017570:MyoD Protein / Q000096:biosynthesis / Q000378:metabolism; D032446:Myoblasts / Q000378:metabolism
chemical_list: C526317:CCN2 protein, human; D017570:MyoD Protein; D055513:Connective Tissue Growth Factor
keywords: C2C12 cells; CCN2; CTGF; TNFα; myoblasts; skeletal myogenesis