title: p21ras as a common signaling target of reactive free radicals and cellular redox stress.
abstract: Reactive free radicals have been implicated in mediating signal transduction by a variety of stimuli. We have investigated the role of p21ras in mediating free radical signaling. Our studies revealed that signaling by oxidative agents which modulate cellular redox status, such as H2O2, hemin, Hg2+, and nitric oxide was prevented in cells in which p21ras activity was blocked either through expression of a dominant negative mutant or by treating with a farnesyltransferase inhibitor, as assessed by NF-kappa B binding activity. Furthermore, the NF-kappa B response to these oxidative stress stimuli was found to be enhanced when cells from the human T cell line, Jurkat, were pretreated with L-buthionine-(S,R)-sulfoximine, an inhibitor of glutathione synthesis. We directly assayed p21ras and mitogen-activated protein kinase activities in Jurkat cells and found both of these signaling molecules to be activated in cells treated with the redox modulating agents. Blocking glutathione synthesis made cells 10- to 100-fold more sensitive to these agents. Finally, using recombinant p21ras in vitro, we found that redox modulators directly promoted guanine nucleotide exchange on p21ras. This study suggests that direct activation of p21ras may be a central mechanism by which a variety of redox stress stimuli transmit their signal to the nucleus.
authors.affiliation: Department of Biochemistry, Cornell University Medical College, New York, New York 10021, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Lander
authors.forename: J S
authors.initials: JS
authors.lastname: Ogiste
authors.forename: K K
authors.initials: KK
authors.lastname: Teng
authors.forename: A
authors.initials: A
authors.lastname: Novogrodsky
mesh_terms: D000818:Animals; D019328:Buthionine Sulfoximine; D002460:Cell Line; D004789:Enzyme Activation; D005609:Free Radicals; D005721:Glutamate-Cysteine Ligase / Q000037:antagonists & inhibitors; D006801:Humans; D008717:Methionine Sulfoximine / Q000031:analogs & derivatives / Q000494:pharmacology; D016328:NF-kappa B / Q000378:metabolism; D015689:Oncogene Protein p21(ras) / Q000378:metabolism*; D010084:Oxidation-Reduction; D018384:Oxidative Stress; D016716:PC12 Cells; D011494:Protein Kinases / Q000378:metabolism; D051381:Rats; D015398:Signal Transduction
chemical_list: D005609:Free Radicals; D016328:NF-kappa B; D008717:Methionine Sulfoximine; D019328:Buthionine Sulfoximine; D011494:Protein Kinases; D015689:Oncogene Protein p21(ras); D005721:Glutamate-Cysteine Ligase