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1Chair of Nephrology, 2Department of Neuroscience, Unit of Physiology, 3Department of Clinical and Experimental Medicine, 4Department of Oral and Maxillofacial Sciences, 5Chair of Nephrology, University Magna Graecia of Catanzaro, and 6Department of Biology and Cellular and Molecular Pathology, University Federico II of Naples, Naples, Italy
Submitted 28 July 2005 ; accepted in final form 18 January 2006
The small GTPase p21 Ras and its downstream effectors play a central role in the control of cell survival and apoptosis. We studied the effects of Ras/ERK1/2 signaling inhibition on oxidative damage in cultured renal and endothelial cells and on renal ischemia-reperfusion injury in the rat. Primary human renal tubular and human endothelial ECV304 cells underwent significant cell death when subjected to oxidative stress. This type of stress induced robustly ERK1/2 and phosphoinositide 3-kinase (PI3-kinase) signaling. Inhibition of Ras/ERK1/2 with a farnesyl transferase inhibitor, chaetomellic acid A (S-FTI), or with PD-98059, an inhibitor of MEK, a kinase upstream ERK1/2, significantly reduced the fraction of dead cells. The inhibitor of the PI3-kinase/Akt pathway, LY-294002, failed to exert a protective effect. We have translated these data in a rat model of renal ischemic injury in vivo. In uninephrectomized animals, anesthetized with pentobarbital sodium (Nembutal, 50 mg/kg ip), 24 h after an acute ischemic renal insult (45-min occlusion of left renal artery) a significant fraction of kidney cells succumbed to cell death resulting in renal failure [glomerular filtration rate (GFR) 0.17 ± 0.1 vs. 0.90 ± 0.4 ml·min1·100 g body wt1 in normal rats]. Rats treated with S-FTI maintained the renal function (GFR 0.50 ± 0.1 ml·min1·100 g body wt1), and the kidneys showed a significant reduction of tubular necrosis. Reduction of ischemic damage in kidney and tubular cells paralleled Ha-Ras inhibition, assayed by cytosolic translocation of the protein. These data demonstrate that inhibition of farnesylation and consequently of Ras/ERK1/2 signaling significantly reduces acute postischemic renal injury.
signal transduction; kidney; endothelium; farnesyl transferase inhibitors
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