Protection from reoxygenation injury by inhibition of rac1.

Abstract

We demonstrate that adenoviral-mediated gene transfer of a dominant negative rac1 gene product (N17rac1) inhibits the intracellular burst of reactive oxygen species (ROS) that occurs after reoxygenation of vascular smooth muscle cells. In contrast, expression of a dominant negative ras gene (N17ras) had no effect. Challenge of control cells and cells expressing N17rac1 with a direct oxidant stress produced an equivalent increase in intracellular ROS levels and subsequent cell death. This suggests that N17rac1 expression appears to block production of harmful oxygen radicals and does not act directly or indirectly to scavenge ROS generated during reoxygenation. Expression of N17rac1 results in protection from hypoxia/reoxygenation-induced cell death in a variety of cell types including vascular smooth muscle cells, fibroblasts, endothelial cells, and ventricular myocytes. These results suggest that reoxygenation injury requires the activation of rac proteins, and that inhibition of rac-dependent pathways may be a useful strategy for the prevention of reperfusion injury in ischemic tissues.

Reactive species mechanisms of cellular hypoxia-reoxygenation injury

“…These kinases may be regulated further by ROS from NAD(P)H oxidase, which requires Rac1 for activity (46). Inhibition of Rac1 lessens both ROS production and reoxygenation injury (58).…”

Nitric oxide synthase and NAD(P)H oxidase modulate coronary endothelial cell growth

“…Although low level production of ROS in non-phagocytic cells seems to be beneficial and is involved in several regulatory cellular processes including gene expression, higher quantities of ROS are implicated in the pathogenesis of atherosclerosis through activating VSMC proliferation and migration [1,13,14]. It is welldocumented that endothelial ROS production increases by several stimuli including pulsatile stretch, hypoxia-reoxygenation and phorbol esters [15][16][17]. However, the precise role of NAD(P)H oxidase in endothelial cell growth remains to be determined.…”

“…The full-length rat endothelial cell p22-phox cDNA was generated using the primers and experimental conditions as previously described [15]. The PCR product was sequenced and cloned in sense and antisense orientations into the expression vector pcDNA 3.1 (Invitrogen).…”

Inhibition of hypoxia/reoxygenation-induced oxidative stress in HGF-stimulated antiapoptotic signaling: role of PI3-K and Akt kinase upon rac1

“…6 Ischemia/reperfusion (I/R) and hypoxia/reoxygenation (H/ R) result in the production of ROS within tissue or cells. 2,7,8 The rac1 small GTPase is an important regulator of ROS production within cells under these circumstances. 7 Rac1 belongs to the rho family of small GTP binding proteins and its role in the production of ROS in phagocytic cells such as neutrophils is well established.…”

“…Rac proteins, in particular rac1, function similarly in nonphagocytic cells, 1,12 and such rac1-regulated ROS have been implicated in a variety of cellular processes including growth, migration, and transformation. 2,8,[12][13][14][15][16][17] We have recently shown that rac1-regulated ROS production also mediates apoptosis in response to I/R. 7 Hepatocyte growth factor (HGF), which was initially isolated as a potent mitogen for hepatocytes, is now known to be a broad-spectrum mitogen for a variety of cell types.…”