ERK and p38 MAPK, but not NF-kappaB, are critically involved in reactive oxygen species-mediated induction of IL-6 by angiotensin II in cardiac fibroblasts.
We recently reported that angiotensin II (Ang II) induced IL-6 mRNA expression in cardiac fibroblasts, which played an important role in Ang II-induced cardiac hypertrophy in paracrine fashion. The present study investigated the regulatory mechanism of Ang II-induced IL-6 gene expression, focusing especially on reactive oxygen species (ROS)-mediated signaling in cardiac fibroblasts. Ang II increased intracellular ROS in cardiac fibroblasts, and the increase was completely inhibited by the AT-1 blocker candesartan and the NADH/NADPH oxidase inhibitor diphenyleneiodonium (DPI). We first confirmed that antioxidant N-acetylcysteine, superoxide scavenger Tiron, and DPI suppressed Ang II-induced IL-6 expression. Because we observed that exogenous H(2)O(2) also increased IL-6 mRNA, the signaling pathways downstream of Ang II and exogenous H(2)O(2) were compared. Ang II, as well as exogenous H(2)O(2), activated ERK, p38 MAPK, and JNK, which were significantly inhibited by N-acetylcysteine and DPI. In contrast with exogenous H(2)O(2), however, Ang II did not influence phosphorylation and degradation of IkappaB-alpha/beta or nuclear translocation of p65, nor did it increase NF-kappaB promoter activity. PD98059 and SB203580 inhibited Ang II-induced IL-6 expression. Truncation and mutational analysis of the IL-6 gene promoter showed that CRE was an important cis-element in Ang II-induced IL-6 gene expression. NF-kappaB-binding site was important for the basal expression of IL-6, but was not activated by Ang II. Ang II phosphorylated CREB through the ERK and p38 MAPK pathway in a ROS-sensitive manner. Collectively, these data indicated that Ang II stimulated ROS production via the AT1 receptor and NADH/NADPH oxidase, and that these ROS mediated activation of MAPKs, which culminated in IL-6 gene expression through a CRE-dependent, but not NF-kappaB-dependent, pathway in cardiac fibroblasts.
Sano
M
M
Cardiopulmonary Division, Department of Internal Medicine, KeioUniversity School of Medicine, Shinjuku, Tokyo, Japan.
Fukuda
K
K
Sato
T
T
Kawaguchi
H
H
Suematsu
M
M
Matsuda
S
S
Koyasu
S
S
Matsui
H
H
Yamauchi-Takihara
K
K
Harada
M
M
Saito
Y
Y
Ogawa
S
S
D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism / Q000494:pharmacology; D015850:Interleukin-6 / Q000096:biosynthesis* / Q000235:genetics; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D016328:NF-kappa B / Q000378:metabolism; D010084:Oxidation-Reduction / Q000187:drug effects; D010766:Phosphorylation / Q000187:drug effects; D011401:Promoter Regions, Genetic / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D048051:p38 Mitogen-Activated Protein Kinases
D017362:Cyclic AMP Response Element-Binding Protein; D004791:Enzyme Inhibitors; D015850:Interleukin-6; D016328:NF-kappa B; D012333:RNA, Messenger; D017382:Reactive Oxygen Species; D000804:Angiotensin II; D006861:Hydrogen Peroxide; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases