title: CD95-tyrosine nitration inhibits hyperosmotic and CD95 ligand-induced CD95 activation in rat hepatocytes.
abstract: Epidermal growth factor receptor-dependent CD95-tyrosine phosphorylation was recently identified as an early step in apoptosis induction via the CD95 system (Reinehr, R., Schliess, F., and Häussinger, D. (2003) FASEB J. 17, 731-733). The effect of peroxynitrite (ONOO(-)) on modulation of the hyperosmotic and CD95 ligand (CD95L)-induced CD95 activation process was studied. Pretreatment of hepatocytes with ONOO(-) inhibited CD95L- and hyperosmolarity-induced CD95 membrane trafficking and formation of the death-inducing signaling complex, but not epidermal growth factor receptor activation and its association with CD95. Under these conditions, however, no tyrosine phosphorylation of CD95 occurred; instead, CD95 was tyrosine-nitrated. When ONOO(-) was added after induction of CD95-tyrosine phosphorylation by CD95L or hyperosmolarity, tyrosine nitration of CD95 was largely prevented and death-inducing signaling complex formation occurred. CD95-tyrosine nitration abolished the hyperosmotic sensitization of hepatocytes toward CD95L-induced apoptosis. Additionally, in CD95-yellow fluorescent protein-transfected Huh7-hepatoma cells, ONOO(-) induced CD95 Tyr nitration and prevented CD95L-induced Tyr phosphorylation and apoptosis. Tyrosine-nitrated CD95 was also found in rat livers derived from an in vivo model of endotoxinemia. The data suggest that CD95-tyrosine nitration prevents CD95 activation by inhibiting CD95-tyrosine phosphorylation. Apparently, CD95-tyrosine phosphorylation and nitration are mutually exclusive. The data identify critical tyrosine residues of CD95 as another target of the anti-apoptotic action of NO.
authors.affiliation: Clinic for Gastroenterology, Hepatology and Infectiology, Heinrich Heine University Düsseldorf, Germany.
authors.forename: Roland
authors.initials: R
authors.lastname: Reinehr
authors.forename: Boris
authors.initials: B
authors.lastname: Görg
authors.forename: Andrea
authors.initials: A
authors.lastname: Höngen
authors.forename: Dieter
authors.initials: D
authors.lastname: Häussinger
mesh_terms: D000818:Animals; D017209:Apoptosis; D001426:Bacterial Proteins / Q000378:metabolism; D002460:Cell Line; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D066246:ErbB Receptors / Q000378:metabolism; D053222:Fas Ligand Protein; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D020287:In Situ Nick-End Labeling; D048031:JNK Mitogen-Activated Protein Kinases; D008099:Liver / Q000378:metabolism; D008164:Luminescent Proteins / Q000378:metabolism; D048670:MAP Kinase Kinase 4; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D009584:Nitrogen / Q000378:metabolism*; D030421:Peroxynitrous Acid / Q000737:chemistry / Q000494:pharmacology; D010766:Phosphorylation; D010957:Plasmids / Q000378:metabolism; D011233:Precipitin Tests; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism*; D019014:fas Receptor / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; C505661:FASLG protein, human; D053222:Fas Ligand Protein; C505662:Faslg protein, rat; D008164:Luminescent Proteins; D008562:Membrane Glycoproteins; D019014:fas Receptor; C054562:yellow fluorescent protein, Bacteria; D030421:Peroxynitrous Acid; D014443:Tyrosine; D066246:ErbB Receptors; D048031:JNK Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D009584:Nitrogen