title: Tumor necrosis factor-like weak inducer of apoptosis inhibits skeletal myogenesis through sustained activation of nuclear factor-kappaB and degradation of MyoD protein.
abstract: In this study we have investigated the effect and the mechanisms by which tumor necrosis factor-like weak inducer of apoptosis (TWEAK) modulates myogenic differentiation. Treatment of C2C12 myoblasts with TWEAK inhibited their differentiation evident by a decrease in the expression of creatine kinase, myosin heavy chain-fast twitch, myogenin, and the formation of multinucleated myotubes. TWEAK also inhibited the differentiation of mouse primary myoblasts. Conversely, the proliferation of C2C12 myoblasts and the expression of a cell-cycle regulator cyclin D1 were increased in response to TWEAK treatment. Inhibition of cellular proliferation using hydroxyurea only partially reversed the inhibitory effect of TWEAK on myogenic differentiation. Treatment of C2C12 myoblasts with TWEAK resulted in the activation of nuclear factor-kappaB (NF-kappaB), the (IkappaB) IkappaB kinase (IKK) complex, and the phosphorylation and degradation of IkappaBalpha protein. Inhibition of NF-kappaB activity by overexpression of a dominant negative mutant of IkappaBalpha (IkappaBalphaDeltaN) significantly increased the myogenic differentiation in TWEAK-treated C2C12 cultures. Furthermore, overexpression of a dominant negative mutant of IKKbeta (IKKbetaK44A) but not IKKalpha (IKKalphaK44M) reversed the inhibitory effect of TWEAK on myogenesis. TWEAK inhibited the expression of myogenic regulatory factors MyoD and myogenin and also induced the degradation of MyoD protein. Finally, inhibition of NF-kappaB activation through overexpression of IKKbetaK44A prevented the degradation of MyoD protein. Overall, our data suggest that TWEAK inhibits myogenesis through the activation of NF-kappaB signaling pathway and degradation of MyoD protein.
authors.affiliation: Molecular Genetics Division, Musculoskeletal Disease Center, Jerry L. Pettis Veterans Administration Medical Center, 11201 Benton Street (151), Loma Linda, CA 92357, USA.
authors.forename: Charu
authors.initials: C
authors.lastname: Dogra
authors.forename: Harish
authors.initials: H
authors.lastname: Changotra
authors.forename: Subburaman
authors.initials: S
authors.lastname: Mohan
authors.forename: Ashok
authors.initials: A
authors.lastname: Kumar
mesh_terms: D000256:Adenoviridae / Q000235:genetics; D000818:Animals; D015153:Blotting, Western; D002454:Cell Differentiation; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism; D049109:Cell Proliferation; D003402:Creatine Kinase / Q000378:metabolism; D019938:Cyclin D1 / Q000378:metabolism; D000074049:Cytokine TWEAK; D003593:Cytoplasm / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005799:Genes, Dominant; D006918:Hydroxyurea / Q000378:metabolism / Q000494:pharmacology; D020672:I-kappa B Proteins / Q000378:metabolism; D051379:Mice; D008856:Microscopy, Fluorescence; D008954:Models, Biological; D015233:Models, Statistical; D009132:Muscles / Q000378:metabolism; D009154:Mutation; D017570:MyoD Protein / Q000378:metabolism; D018008:Myogenin / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D013997:Time Factors; D048069:Tumor Necrosis Factors / Q000378:metabolism*
chemical_list: D000074049:Cytokine TWEAK; D020672:I-kappa B Proteins; D017570:MyoD Protein; D018008:Myogenin; D016328:NF-kappa B; C000606205:Nfkbia protein, mouse; C491645:Tnfsf12 protein, mouse; D048069:Tumor Necrosis Factors; D019938:Cyclin D1; D000072000:NF-KappaB Inhibitor alpha; D003402:Creatine Kinase; D006918:Hydroxyurea