Role of NAD(P)H oxidase in angiotensin II-induced JAK/STAT signaling and cytokine induction.
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 (O(2)(-)) anions activate this signaling cascade, and the vasoconstrictor angiotensin II (Ang II) enhances the formation of O(2)(-) 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 (AT(1)) receptor and induces synthesis and release of IL-6. Therefore, we investigated the role of O(2)(-) 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 O(2)(-) anions determined by laser fluoroscopy, which can be abolished by DPI, a flavoprotein inhibitor. Ang II-induced phosphorylation of JAK2, STAT1alpha/ss, 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(phox), 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 micromol/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 O(2)(-) anions generated by the NAD(P)H oxidase system, and O(2)(-) 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 O(2)(-) anions generated by the NAD(P)H oxidase system.
Schieffer
B
B
Department of Cardiology and Angiology, Medizinische Hochschule Hannover, Germany. Schieffer.Bernhard@MH-Hannover.de
Luchtefeld
M
M
Braun
S
S
Hilfiker
A
A
Hilfiker-Kleiner
D
D
Drexler
H
H
D000804:Angiotensin II / Q000502:physiology*; D000818:Animals; D002478:Cells, Cultured; D016207:Cytokines / Q000096:biosynthesis*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004790:Enzyme Induction; D053614:Janus Kinase 2; D019255:NADPH Oxidases / Q000502:physiology*; D018384:Oxidative Stress; D010750:Phosphoproteins / Q000032:analysis / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000096:biosynthesis*; D011518:Proto-Oncogene Proteins; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism; D050794:STAT1 Transcription Factor; D015398:Signal Transduction; D015534:Trans-Activators / Q000096:biosynthesis*
D016207:Cytokines; D004268:DNA-Binding Proteins; D010750:Phosphoproteins; D011518:Proto-Oncogene Proteins; D017382:Reactive Oxygen Species; D050794:STAT1 Transcription Factor; D015534:Trans-Activators; D000804:Angiotensin II; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D011505:Protein-Tyrosine Kinases; C507927:Jak2 protein, rat; D053614:Janus Kinase 2