Role of reactive oxygen species in bradykinin-induced proliferation of vascular smooth muscle cells

Victoria Velarde,Eduardo Abbott,Francisca Arancibia,Francesca Moreno,Paula M De La Cerda,Claudia Duarte,Alejandro González,Ayad A Jaffa

doi:10.4067/s0716-97602004000300007

Abstract

In addition to the induction of cell proliferation and migration, bradykinin (BK) can increase c-fos mRNA expression, activate ERK 1/2 and generate reactive oxygen species (ROS) in vascular smooth muscle cells (VSMC). It is not known, however, whether BK can induce cellular proliferation and extracellular matrix production via redox-sensitive signaling pathways. We investigated the role(s) of ROS in proliferation, migration and collagen synthesis induced by BK in VSMC derived from Sprague Dawley rat aorta. BK (10 nM) increased VSMC proliferation by 30% (n=5); this proliferation was inhibited by the antioxidants N-acetylcysteine (20 mM) and alpha-lipoic acid (LA, 250 mM). In addition, BK induced an increase in cell migration and in collagen levels that were blocked by LA. ROS production induced by BK (n=10) was significantly inhibited by bisindolylmaleimide (4microM) and by PD98059 (40microM). These results suggest that: 1) ROS participate in the mechanism(s) used by bradykinin to induce cellular proliferation; 2) bradykinin induces ROS generation through a pathway that involves the kinases PKC and MEK; and 3) ROS participate in the pathways mediating cell migration and the production of collagen as a response to treatment with bradykinin. To our knowledge, this is the first report describing mechanisms to explain the participation of ROS in the cellular proliferation and extracellular matrix pathway regulated by BK.

Highlights

Vascular smooth muscle cells (VSMC) in mature animals are highly specialized cells that have as one of their major functions the regulation of vascular tone via contraction (Owens, 1995)
To determine whether cell proliferation was mediated by the generation of reactive oxygen species (ROS), VSMC were preincubated with the antioxidants α-lipoic acid (LA, 250 μM) for 2 hours or Nacetylcysteine (NAC, 15 mM) for 45 minutes followed by a 24-hour incubation with BK (10 nM)
To determine whether ROS was mediating BK-induced NF-κB activation in VSMC, we stimulated the cells for 30 min with increasing concentrations of BK (10-9 to 10-7 M) and observed a dose-dependent increase in NF-κB signaling in the nucleus (Fig 2A)

Summary

Introduction

Vascular smooth muscle cells (VSMC) in mature animals are highly specialized cells that have as one of their major functions the regulation of vascular tone via contraction (Owens, 1995). VSMC proliferation is normally quiescent in the adult, and mitogenic activity is rarely exhibited when cells contract during the hemodynamic regulation state. In disease where significant vascular injury occurs, such as diabetes and hypertension, VSMC growth is stimulated when the physiologic and regulatory balances between inhibitory and stimulatory signals are disrupted. These alterations in the signals for cell growth and matrix production can lead to atherosclerosis and its subsequent progression. Dysfunction of and/or damage to the endothelial cells lining the vasculature accompanied by reductions in the production of nitric oxide are postulated to have a major role in increased VSMC proliferation (Bauer et al, 2001)

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