B. Schieffer et al., Role of NAD(P)H oxidase in angiotensin II-induced JAK/STAT signaling and cytokine induction, CIRCUL RES, 87(12), 2000, pp. 1195-1201
Inflammatory processes involve both synthesis of inflammatory cytokines, su
ch as interleukin-6 (IL-6), and the activation of their distinct signaling
pathways, eg, the janus kinases (JAKs) and signal transducers and activator
s of transcription (STAT), Superoxide (O-2(-)) anions activate this signali
ng cascade, and the vasoconstrictor angiotensin II (Ang II) enhances the fo
rmation of O-2(-) anions via the NAD(P)H oxidase system in rat aortic smoot
h 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 investig
ated the rule of O-2(-) anions generated by the NAD(P)H oxidase system on t
he Ang II activation of the JAK/STAT cascade and its impact on IL-6 synthes
is. Ang II stimulation of rat aortic smooth muscle cells induced a rapid in
crease in O-2(-) anions determined by laser fluoroscopy, which can be aboli
shed by DPI, a flavoprotein inhibitor. Ang Ii-induced phosphorylation of JA
K2, STAT1 alpha/beta, STAT3, and IL-6-synthesis can be abolished by DPI, as
determined by immunoprecipitations and Northern blot analysis. Electropora
tion of neutralizing antisera targeted against p47(phox), a NAD(P)II oxidas
e subunit, abolished Ang II-induced JAK/STAT activation and IL-6 synthesis.
Inhibition of JAK2 by its inhibitor AG490 (10 mu mol/L) blocked not only J
AK2 activation but also IL-6 synthesis. These results suggest that stimulat
ion of the JAK/STAT cascade by Ang II requires O-2(-) anions generated by t
he 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 synt
hesis. Thus, Ang II-induced inflammatory effects seem to require O-2(-) ani
ons generated by the NAD(P)H oxidase system.