IL-1beta stimulates IL-6 production in cultured skeletal muscle cells through activation of MAP kinase signaling pathway and NF-kappa B.
Recent studies suggest that the skeletal muscle may be a significant site of IL-6 production in various conditions, including exercise, inflammation, hypoperfusion, denervation, and local muscle injury. The mediators and molecular mechanisms regulating muscle IL-6 production are poorly understood. We tested the hypothesis that IL-6 production in muscle cells is regulated by IL-1beta and that mitogen-activated protein (MAP) kinase signaling and NF-kappaB activation are involved in IL-1beta-induced IL-6 production. Cultured C2C12 cells, a mouse skeletal muscle cell line, were treated with different concentrations (0.1-2 ng/ml) of IL-1beta in the absence or presence of the p38 MAP kinase inhibitor SB-208350 or the p42/44 inhibitor PD-98059. Protein and gene expression of IL-6 were determined by ELISA and real-time PCR, respectively. NF-kappaB DNA binding activity was determined by electrophoretic mobility shift assay and by transfecting myocytes with a luciferase reporter plasmid containing a promoter construct with multiple repeats of NF-kappaB binding site. Treatment of myotubes with IL-1beta resulted in a dose- and time-dependent increase of IL-6 production accompanied by an approximately 25-fold increase in IL-6 mRNA levels. IL-1beta stimulated NF-kappaB DNA binding activity and gene activation. SB-208350 and PD-98059 inhibited the increase in IL-6 production induced by IL-1beta. The present results support the concept that skeletal muscle is an important site of IL-6 production. In addition, the results suggest the IL-1beta regulates muscle IL-6 production at least in part by activating the MAP kinase pathway and NF-kappaB.
Luo
Guangjo
G
Department of Surgery, University of Cincinnati, Cincinnati, and Shriners Hospitals for Children, Cincinnati, Ohio 45267, USA.
Hershko
Dan D
DD
Robb
Bruce W
BW
Wray
Curtis J
CJ
Hasselgren
Per-Olof
PO
D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology*; D015850:Interleukin-6 / Q000096:biosynthesis*; D020935:MAP Kinase Signaling System / Q000187:drug effects*; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D018482:Muscle, Skeletal / Q000502:physiology*; D016328:NF-kappa B / Q000378:metabolism*; D013997:Time Factors
D004791:Enzyme Inhibitors; D005419:Flavonoids; D007375:Interleukin-1; D015850:Interleukin-6; D016328:NF-kappa B; D020928:Mitogen-Activated Protein Kinases; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one