title: Noncanonical cAMP pathway and p38 MAPK mediate beta2-adrenergic receptor-induced IL-6 production in neonatal mouse cardiac fibroblasts.
abstract: We previously reported that cardiac fibroblasts, but not cardiomyocytes, are served as the predominant source of IL-6 after isoproterenol stimulation in mouse myocardium. The present study investigated the molecular mechanism of isoproterenol-mediated secretion of IL-6 in mouse cardiac fibroblasts. Treatment of cells with isoproterenol-induced a time-dependent accumulation of IL-6, which was mediated by beta(2)-adrenergic receptor (AR), the preponderant beta-AR subtype in cardiac fibroblasts. Isoproterenol-induced secretion of IL-6 was mainly mediated by Gs-AC-cAMP signaling cascade and could be negatively regulated by Gi and PI3K. Surprisingly, the effect of cAMP was independent of protein kinase A and the exchange protein directly activated by cAMP (Epac)-Rap1 pathway and suggests the existence of a novel cAMP-dependent mechanism. p38 MAPK inhibitor SB203580, but not extracellular regulated protein kinase inhibitor, abrogated isoproterenol-induced IL-6 release in cardiac fibroblasts and mouse myocardium. Interestingly, p38 MAPK could also be positively regulated by Gs-AC-cAMP but negatively regulated by Gi-PI3K pathway. Finally, multiple transcription factors (AP-1, C/EBP, NF-kappaB and CREB) regulating the IL-6 gene are activated in response to isoproterenol stimulation, which may provide essential linkage between upstream cAMP-p38 MAPK signaling cascade and downstream IL-6 gene transcription. The present results suggest that beta(2)-AR mediates IL-6 production through a noncanonical cAMP responsible pathway and p38 MAPK.
authors.affiliation: Institute of Vascular Medicine, Peking University Third Hospital, Beijing 100083, China.
authors.forename: Feng
authors.initials: F
authors.lastname: Yin
authors.forename: Yong-Yu
authors.initials: YY
authors.lastname: Wang
authors.forename: Jian-Hai
authors.initials: JH
authors.lastname: Du
authors.forename: Chun
authors.initials: C
authors.lastname: Li
authors.forename: Zhi-Zhen
authors.initials: ZZ
authors.lastname: Lu
authors.forename: Chide
authors.initials: C
authors.lastname: Han
authors.forename: You-Yi
authors.initials: YY
authors.lastname: Zhang
mesh_terms: D000318:Adrenergic beta-Agonists / Q000494:pharmacology; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000032:analysis / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000032:analysis / Q000096:biosynthesis; D004797:Enzyme-Linked Immunosorbent Assay; D005347:Fibroblasts / Q000201:enzymology* / Q000378:metabolism; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes; D015850:Interleukin-6 / Q000378:metabolism*; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D051379:Mice; D008807:Mice, Inbred BALB C; D008954:Models, Biological; D009206:Myocardium / Q000166:cytology; D018343:Receptors, Adrenergic, beta-2 / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012235:Rhodamines; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism*
chemical_list: D000318:Adrenergic beta-Agonists; D005456:Fluorescent Dyes; D015850:Interleukin-6; D018343:Receptors, Adrenergic, beta-2; D012235:Rhodamines; C009434:tetramethylrhodamine isothiocyanate; D000242:Cyclic AMP; D017868:Cyclic AMP-Dependent Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D007545:Isoproterenol