Enhancement of protein kinase C-dependent O2 production in Epstein-Barr virus-transformed B lymphocytes by p120Ras-GAP antisense oligonucleotide.
The mammalian Ras GTPase-activating protein (p120Ras-GAP) interacts with activated members of the Ras superfamily of GTP-binding proteins to accelerate their deactivation by sharply increasing their rates of GTP hydrolysis. Among the Ras-family proteins interacting with p120Ras-GAP is Rap1A/Krev1, whose activity is not affected by p120Ras-GAP but which competes with Ras for p120Ras-GAP. A second protein that interacts with p120Ras-GAP is P190Rac-GAP, which activates the GTPase of guanine nucleotide-binding proteins of the Rho family (including Rac1 and Rac2). Both these p120Ras-GAP-binding proteins are of interest in connection with the regulation of the respiratory burst oxidase, Rap1A/Krev1 because it copurifies with cytochrome b558 and p190Ras-GAP because it inhibits the Rac2-dependent activation of the respiratory burst oxidase in a cell-free system. Using an 18-mer antisense oligonucleotide, we were able to decrease the expression of p120Ras-GAP in Epstein-Barr virus-transformed B lymphocytes. Under conditions where p120Ras-GAP expression was significantly depressed by antisense oligonucleotides, we observed a 40% increase in protein kinase C-dependent but not receptor-dependent O2 production. In contrast, sense and scrambled oligonucleotides had no effect on either p120Ras-GAP expression or O2 production. Our results suggest a role for p120Ras-GAP as a negative regulator in the protein kinase C-mediated activation of the respiratory burst oxidase.
Schmid
E
E
Department of Molecular and Experimental Medicine, The Scripps Research Institute, La Jolla, California 92037, USA.
Koziol
J A
JA
Babior
B M
BM
D001402:B-Lymphocytes / Q000187:drug effects / Q000502:physiology*; D001483:Base Sequence; D002460:Cell Line; D002472:Cell Transformation, Viral; D004791:Enzyme Inhibitors / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000378:metabolism; D020690:GTPase-Activating Proteins; D004854:Herpesvirus 4, Human / Q000235:genetics*; D006801:Humans; D015759:Ionomycin / Q000494:pharmacology; D007700:Kinetics; D008969:Molecular Sequence Data; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism*; D019255:NADPH Oxidases; D016376:Oligonucleotides, Antisense / Q000494:pharmacology*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011506:Proteins / Q000235:genetics* / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism*; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013997:Time Factors; D020744:rac GTP-Binding Proteins; D020703:ras GTPase-Activating Proteins
D004791:Enzyme Inhibitors; D020690:GTPase-Activating Proteins; D016376:Oligonucleotides, Antisense; D011506:Proteins; D020703:ras GTPase-Activating Proteins; D013481:Superoxides; D015759:Ionomycin; D009247:NADH, NADPH Oxidoreductases; D019255:NADPH Oxidases; C022709:superoxide-forming enzyme; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D020744:rac GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate