title: β-agonists selectively modulate proinflammatory gene expression in skeletal muscle cells via non-canonical nuclear crosstalk mechanisms.
abstract: The proinflammatory cytokine Tumour Necrosis Factor (TNF)-α is implicated in a variety of skeletal muscle pathologies. Here, we have investigated how in vitro cotreatment of skeletal muscle C2C12 cells with β-agonists modulates the TNF-α-induced inflammatory program. We observed that C2C12 myotubes express functional TNF receptor 1 (TNF-R1) and β2-adrenoreceptors (β2-ARs). TNF-α activated the canonical Nuclear Factor-κB (NF-κB) pathway and Mitogen-Activated Protein Kinases (MAPKs), culminating in potent induction of NF-κB-dependent proinflammatory genes. Cotreatment with the β-agonist isoproterenol potentiated the expression of inflammatory mediators, including Interleukin-6 (IL-6) and several chemokines. The enhanced production of chemotactic factors upon TNF-α/isoproterenol cotreatment was also suggested by the results from migrational analysis. Whereas we could not explain our observations by cytoplasmic crosstalk, we found that TNF-R1-and β2-AR-induced signalling cascades cooperate in the nucleus. Using the IL-6 promoter as a model, we demonstrated that TNF-α/isoproterenol cotreatment provoked phosphorylation of histone H3 at serine 10, concomitant with enhanced promoter accessibility and recruitment of the NF-κB p65 subunit, cAMP-response element-binding protein (CREB), CREB-binding protein (CBP) and RNA polymerase II. In summary, we show that β-agonists potentiate TNF-α action, via nuclear crosstalk, that promotes chromatin relaxation at selected gene promoters. Our data warrant further study into the mode of action of β-agonists and urge for caution in their use as therapeutic agents for muscular disorders.
authors.affiliation: Department of Medical Protein Research, VIB, Gent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium.
authors.forename: Krzysztof
authors.initials: K
authors.lastname: Kolmus
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium.
authors.forename: Marleen
authors.initials: M
authors.lastname: Van Troys
authors.affiliation: Department of Physiology, Faculty of Sciences, Ghent University, Gent, Belgium.
authors.forename: Karlien
authors.initials: K
authors.lastname: Van Wesemael
authors.affiliation: Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium.
authors.forename: Christophe
authors.initials: C
authors.lastname: Ampe
authors.affiliation: Department of Physiology, Faculty of Sciences, Ghent University, Gent, Belgium.
authors.forename: Guy
authors.initials: G
authors.lastname: Haegeman
authors.affiliation: Department of Medical Protein Research, VIB, Gent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium.
authors.forename: Jan
authors.initials: J
authors.lastname: Tavernier
authors.affiliation: Department of Medical Protein Research, VIB, Gent, Belgium; Department of Biochemistry, Faculty of Medicine and Health Sciences, Ghent University, Gent, Belgium.
authors.forename: Sarah
authors.initials: S
authors.lastname: Gerlo
mesh_terms: D058666:Adrenergic beta-2 Receptor Agonists / Q000494:pharmacology*; D000818:Animals; D002460:Cell Line; D002465:Cell Movement; D042002:Chromatin Assembly and Disassembly / Q000187:drug effects; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D044127:Epigenesis, Genetic / Q000187:drug effects; D015870:Gene Expression; D006657:Histones / Q000378:metabolism; D018836:Inflammation Mediators / Q000378:metabolism; D015850:Interleukin-6 / Q000235:genetics* / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology; D051379:Mice; D032448:Myoblasts, Skeletal / Q000187:drug effects / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D011401:Promoter Regions, Genetic; D020239:Receptor Cross-Talk; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I / Q000378:metabolism; D015398:Signal Transduction; D014409:Tumor Necrosis Factor-alpha / Q000502:physiology
chemical_list: D058666:Adrenergic beta-2 Receptor Agonists; D017362:Cyclic AMP Response Element-Binding Protein; D006657:Histones; D018836:Inflammation Mediators; D015850:Interleukin-6; D016328:NF-kappa B; D018343:Receptors, Adrenergic, beta-2; D047888:Receptors, Tumor Necrosis Factor, Type I; C506236:Tnfrsf1a protein, mouse; D014409:Tumor Necrosis Factor-alpha; D017868:Cyclic AMP-Dependent Protein Kinases; D007545:Isoproterenol