Objective-Oxidative stress mediated by Nox1-and Nox4-based NADPH oxidase (Nox) plays a key role in vascular diseases. The molecular mechanisms involved in the regulation of Nox are not entirely elucidated. Because JAK/STAT regulates many genes linked to inflammation, cell proliferation, and differentiation, we questioned whether this pathway is involved in the regulation of Nox1 and Nox4 in human aortic smooth muscle cells (SMCs). Methods and Results-Cultured SMCs were exposed to interferon ␥ (IFN␥) for 24 hours. Using lucigenin-enhanced chemiluminescence and dihydroethidium assays, real-time polymerase chain reaction, and Western blot analysis, we found that JAK/STAT inhibitors significantly diminished the IFN␥-dependent upregulation of Nox activity, Nox1 and Nox4 expression. In silico analysis revealed the presence of highly conserved GAS elements within human Nox1, Nox4, p22phox, p47phox, and p67phox promoters. Transient overexpression of STAT1/STAT3 augmented the promoter activities of each subunit. JAK/STAT blockade reduced the Nox subunits transcription. Chromatin immunoprecipitation demonstrated the physical interaction of STAT1/STAT3 proteins with the predicted GAS elements from Nox1 and Nox4 promoters. Key Words: NADPH oxidase Ⅲ JAK/STAT Ⅲ oxidative stress Ⅲ atherosclerosis E merging clinical and experimental evidence demonstrate the role of oxidative stress in the development of cardiovascular disorders. Reactive oxygen species (ROS) are implicated in different cell processes associated to vascular plaque formation such as growth, proliferation, differentiation, and apoptosis of smooth muscle cells (SMCs). 1,2 Deciphering the molecular mechanisms underlying the regulation of ROS production may lead to new therapeutic approaches.
Conclusions-JAK/STATNADPH oxidases (Nox) are regulated by a plethora of stimuli and represent a major source of ROS in the vasculature. Depending on the cell type, the vascular Nox comprises 3 distinct catalytic subunits (Nox1, Nox2, Nox4) and 6 cytosolic regulatory components (p47phox, p67phox, NoxO1, NoxA1, Rac1/2). The p22phox component is essential for Nox activity forming a bound complex with 4 SMCs express predominantly Nox1 and Nox4 isoforms, which are differentially distributed in the cellular compartments and direct several redox-dependent processes. 5 It was postulated that Nox1 associates with and promotes SMCs proliferation, whereas Nox4 is required for the maintenance of differentiated phenotype. 6 Changes in gene expression of the Nox isoforms are critical for its function. In previous studies we showed that the expression of p22phox subunit and the ensuing superoxide production is regulated by NF-kB and AP-1 in human aortic SMCs. 7,8 However, the transcriptional regulatory mechanisms of oxidase components are not entirely elucidated.Activation of Janus tyrosine kinase/signal transducers and activators of transcription (JAK/STAT) signaling pathway is an essential pathogenic mechanism leading to SMC hypertrophy and hyperplasia. It was shown that STAT1 and STAT...
