Protection of human endothelial cells from oxidative stress: role of Ras-ERK1/2 signaling.
BACKGROUND
Reactive oxygen species play a critical role in inducing apoptosis. The small GTPase p21 Ras and the ERK1/2 MAPK have been proposed as key regulators of the signaling cascade triggered by oxidative stress (H2O2). Harvey-Ras (Ha-Ras) and Kirsten-Ras (Ki-Ras) isoforms are so far functionally indistinguishable, because they activate the same downstream effectors, including ERK1/2. Moreover, ERK1/2 signaling has been involved in both protection and induction of apoptosis.


RESULTS
Human umbilical vein endothelial cells (HUVECs) were subjected to H2O2, and apoptosis was detected by fluorescence-activated cell sorting analysis, fluorescence microscopy, and caspase-3 activation. Transfection of Ha-Ras and Ki-Ras genes in HUVECs was performed to evaluate the response to H2O2. We have found that, whereas Ha-Ras decreases tolerance to oxidative stress, Ki-Ras has a potent antiapoptotic activity. Both effects are mediated by ERK1/2. Tolerance to H2O2 is encoded by a unique stretch of lysines at the COOH terminus of the Ki-Ras, lacking in Ha-Ras, and it is relatively independent of the farnesylated anchor. Inhibition of p21 Ras signaling by farnesylation inhibitors increased the resistance to apoptosis in Ha-Ras-expressing cells.


CONCLUSIONS
These findings explain the opposite effects of ERK1/2 stimulation on apoptosis found in different cell types and suggest that local activation of ERK1/2 signaling may account for the opposing response to oxidative stress by Ha-Ras or Ki-Ras-expressing cells. Modulation of cell reactivity to oxidative stress by p21 Ras points to the specific and predictive effects of Ras inhibitors in vivo as potential therapeutic drugs in disorders produced by increase of reactive oxygen species inside the cells.
Cuda
Giovanni
G
Dipartimento di Medicina Sperimentale e Clinica G. Salvatore, Università di Catanzaro Magna Graecia, Napoli, Italy.
Paternò
Roberto
R
Ceravolo
Roberto
R
Candigliota
Mafalda
M
Perrotti
Nicola
N
Perticone
Francesco
F
Faniello
Maria Concetta
MC
Schepis
Filippo
F
Ruocco
Antonio
A
Mele
Evelina
E
Cassano
S
S
Bifulco
Maurizio
M
Santillo
Mariarosaria
M
Avvedimento
Enrico V
EV
D019943:Amino Acid Substitution; D017209:Apoptosis / Q000187:drug effects; D002478:Cells, Cultured; D019610:Cytoprotection / Q000187:drug effects; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005799:Genes, Dominant; D011905:Genes, ras; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008715:Methionine / Q000031:analogs & derivatives* / Q000494:pharmacology; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015689:Oncogene Protein p21(ras) / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects / Q000502:physiology*; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism / Q000494:pharmacology; D017368:Protein Prenylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013329:Structure-Activity Relationship; D014162:Transfection
D004791:Enzyme Inhibitors; C096856:FTI 277; D020033:Protein Isoforms; D017382:Reactive Oxygen Species; D008715:Methionine; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D015689:Oncogene Protein p21(ras)