Role of NAD(P)H Oxidase in Angiotensin II–Induced JAK/STAT Signaling and Cytokine Induction

• Published in: Circulation research 2000-12, Vol.87 (12), p.1195-1201
• Main Authors: Schieffer, Bernhard, Luchtefeld, Maren, Braun, Sabine, Hilfiker, Andres, Hilfiker-Kleiner, Denise, Drexler, Helmut
• Format: Article
• Language: English
• Subjects: Angiotensin II - physiology; Animals; Atherosclerosis (general aspects, experimental research); Biological and medical sciences; Blood and lymphatic vessels; Cardiology. Vascular system; Cells, Cultured; Cytokines - biosynthesis; DNA-Binding Proteins - biosynthesis; Enzyme Induction; Janus Kinase 2; Medical sciences; NADPH Oxidases - physiology; Oxidative Stress; Phosphoproteins - analysis; Phosphoproteins - genetics; Protein-Tyrosine Kinases - biosynthesis; Proto-Oncogene Proteins; Rats; Reactive Oxygen Species - metabolism; Signal Transduction; STAT1 Transcription Factor; Trans-Activators - biosynthesis
• ISSN: 0009-7330; 1524-4571
• DOI: 10.1161/01.res.87.12.1195

ABSTRACT—Inflammatory processes involve both synthesis of inflammatory cytokines, such as interleukin-6 (IL-6), and the activation of their distinct signaling pathways, eg, the janus kinases (JAKs) and signal transducers and activators of transcription (STAT). Superoxide (O2) anions activate this signaling cascade, and the vasoconstrictor angiotensin II (Ang II) enhances the formation of O2 anions via the NAD(P)H oxidase system in rat aortic smooth muscle cells. Ang II activates the JAK/STAT cascade via its type 1 (AT1) receptor and induces synthesis and release of IL-6. Therefore, we investigated the role of O2 anions generated by the NAD(P)H oxidase system on the Ang II activation of the JAK/STAT cascade and its impact on IL-6 synthesis. Ang II stimulation of rat aortic smooth muscle cells induced a rapid increase in O2 anions determined by laser fluoroscopy, which can be abolished by DPI, a flavoprotein inhibitor. Ang II–induced phosphorylation of JAK2, STAT1α/β, STAT3, and IL-6-synthesis can be abolished by DPI, as determined by immunoprecipitations and Northern blot analysis. Electroporation of neutralizing antisera targeted against p47, a NAD(P)H oxidase subunit, abolished Ang II–induced JAK/STAT activation and IL-6 synthesis. Inhibition of JAK2 by its inhibitor AG490 (10 μmol/L) blocked not only JAK2 activation but also IL-6 synthesis. These results suggest that stimulation of the JAK/STAT cascade by Ang II requires O2 anions generated by the NAD(P)H oxidase system, and O2 anion–dependent activation of the JAK/STAT cascade seems to be additionally involved in Ang II–induced IL-6 synthesis. Thus, Ang II–induced inflammatory effects seem to require O2 anions generated by the NAD(P)H oxidase system.