Human Urotensin II Is a Novel Activator of NADPH Oxidase in Human Pulmonary Artery Smooth Muscle Cells

Abstract

Background-Human urotensin II (hU-II) is a potent vasoactive peptide possibly involved in pulmonary hypertension.Because the signaling mechanisms activated by this peptide in the pulmonary vasculature are largely unknown, we investigated the role of hU-II in the activation of NADPH oxidase and the control of redox-sensitive kinase pathways, expression of plasminogen activator inhibitor-1 (PAI-1), and proliferation in pulmonary artery smooth muscle cells (PASMCs). Methods and Results-hU-II upregulated expression of the NADPH oxidase subunits p22phox and NOX4 and increased the levels of reactive oxygen species (ROS), which were abrogated by transfecting p22phox or NOX4 antisense vectors. p22phox and NOX4 also contributed to hU-II-induced activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase, c-Jun N-terminal kinase, and protein kinase B (Akt). Furthermore, hU-II increased the expression of PAI-1 and enhanced PASMC proliferation in an NADPH oxidase-and kinase-dependent manner. Conclusions-hU-II is a potent activator of ROS generation by NADPH oxidase in PASMCs, leading to redox-sensitive activation of mitogen-activated protein kinases and Akt and subsequently to enhanced PAI-1 expression and increased proliferation. These findings suggest that hU-II may play a novel role in pulmonary hypertension by promoting remodeling processes via activation of NADPH oxidases.

Urotensin II receptor antagonism confers vasoprotective effects in diabetes associated atherosclerosis: studies in humans and in a mouse model of diabetes

“…It is well known that oxidative stress is a potential mediator of atherosclerosis, particularly in the diabetic context [28], and UII is known to act via NADPH oxidase (NOX)4 in smooth muscle cells [29,30]. Indeed, in our in vitro studies, various NOX isoforms were activated, a phenomenon that appeared to be UII-dependent and attenuable by SB-657510.…”

Angiotensin II and the JNK pathway mediate urotensin II expression in response to hypoxia in rat cardiomyocytes

“…Transcriptional regulation of UII-R by nuclear receptor-kB and hypoxia-inducible factor-1a has been reported (Segain et al 2007, Gould et al 2010. Moreover, the JNK pathway has been reported to mediate the oxidative stress induced by UII (Djordjevic et al 2005). Our recent study documented that hypoxia-induced UII expression in cardiac fibroblasts is mediated by AngII and through the ROS and JNK pathways .…”

Nox enzymes, ROS, and chronic disease: An example of antagonistic pleiotropy

“…This perturbed redox-dependent signaling is proposed to contribute to smooth muscle hypertrophy and proliferation that is associated with pulmonary hypertension [39].…”