Interleukin-6 family of cytokines mediates isoproterenol-induced delayed STAT3 activation in mouse heart.
This study was aimed to determine whether beta-adrenergic receptor (beta-AR) stimulated by isoproterenol (ISO) activates signal transducers and activators of transcription (STAT) in mouse heart and, if so, to examine the underlying mechanism. We found that treatment of adult male mice by ISO (15 mg/kg body weight, intraperitoneal) caused a delayed STAT3 activation (at 60-120 min), which was fully abolished by beta-AR antagonist, propranolol. ISO-induced phosphorylation of STAT3 was markedly enhanced by phosphodiesterase inhibitor amrinone, indicating that cAMP is critically involved in beta-AR-mediated STAT3 activation. In addition, beta-AR stimulation significantly increased gene expression of interleukin-6 (IL-6) family of cytokines (IL-6, leukemia inhibitory factor, ciliary neurotrophic factor, and cardiotrophin-1). IL-6 protein levels in serum and mouse myocardium were also significantly increased in response to ISO treatment. In cultured cardiac fibroblasts, IL-6 level was enhanced significantly after ISO (10-6 mol/liter) stimulation for 2 h and then peaked at 12 h, whereas the response of IL-6 in cultured cardiomyocytes to ISO stimulation was not significant, suggesting that ISO-induced increase in IL-6 is primarily from cardiac fibroblasts rather than cardiomyocytes. Most importantly, IL-6 could activate STAT3 in a time-dependent manner in cultured cardiomyocytes, and inhibition of IL-6 level by anti-IL-6-neutralizing antibody clearly attenuated ISO-induced phosphorylation of STAT3 in myocardium. Taken together, these results indicate that beta-AR stimulation leads to a delayed STAT3 activation via an IL-6 family of cytokine-mediated pathway and that cardiac fibroblasts, but not cardiomyocytes, is probably the predominant source of IL-6 in response to ISO stimulation in mouse myocardium.
Yin
Feng
F
Institute of Vascular Medicine, Peking University Third Hospital and The Reference Laboratory of Education Ministry on Molecular Cardiology, Beijing 100083, People's Republic of China.
Li
Ping
P
Zheng
Ming
M
Chen
Li
L
Xu
Qi
Q
Chen
Kai
K
Wang
Yong-yu
YY
Zhang
You-yi
YY
Han
Chide
C
D000318:Adrenergic beta-Agonists / Q000494:pharmacology*; D000818:Animals; D000906:Antibodies / Q000494:pharmacology; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D015850:Interleukin-6 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D007545:Isoproterenol / Q000494:pharmacology*; D053613:Janus Kinase 1; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D009206:Myocardium / Q000166:cytology / Q000276:immunology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000166:cytology / Q000378:metabolism; D010766:Phosphorylation; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D050796:STAT3 Transcription Factor; D015534:Trans-Activators / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects / Q000276:immunology; D020257:Ventricular Remodeling / Q000187:drug effects / Q000502:physiology
D000318:Adrenergic beta-Agonists; D000906:Antibodies; D004268:DNA-Binding Proteins; D015850:Interleukin-6; D050796:STAT3 Transcription Factor; C494087:Stat3 protein, mouse; D015534:Trans-Activators; D014443:Tyrosine; D000242:Cyclic AMP; D011505:Protein-Tyrosine Kinases; C507905:Jak1 protein, mouse; D053613:Janus Kinase 1; D007545:Isoproterenol