title: Inositol 1,3,4-trisphosphate 5/6-kinase inhibits tumor necrosis factor-induced apoptosis.
abstract: Tumor necrosis factor receptor 1 (TNF-R1) signaling elicits a wide range of biological responses, including inflammation, proliferation, differentiation, and apoptosis. TNF-R1 activates both caspase-mediated apoptosis and NF-kappaB transcription of anti-apoptotic factors. We now report a link between the TNF-R1 and inositol phosphate signaling pathways. We observed that overexpression of inositol 1,3,4-trisphosphate 5/6-kinase (5/6-kinase) inhibited apoptosis induced by TNFalpha. The anti-apoptotic effect by 5/6-kinase is not attributable to NF-kappaB activation, as no changes were detected in the levels of NF-kappaB DNA binding, IkappaBalpha degradation, or anti-apoptotic factors, such as x-linked inhibitor of apoptosis protein. Decreased expression of 5/6-kinase by RNA interference rendered HeLa cells more susceptible to TNFalpha-induced apoptosis. Overexpression of 5/6-kinase in human embryonic kidney 293 cells inhibited TNFalpha-induced activation of caspases-8, -3, and -9, BID, and poly(ADP-ribose) polymerase. However, 5/6-kinase did not protect against Fas-, etoposide-, or cycloheximide-induced apoptosis. Further, 5/6-kinase protected against apoptosis induced by the overexpression of TNF-R1-associated death domain but not Fas-associated death domain. Therefore, we suggest that 5/6-kinase modifies TNFalpha-induced apoptosis by interfering with the activation of TNF-R1-associated death domain.
authors.affiliation: Department of Internal Medicine, Division of Hematology, Washington University School of Medicine, St. Louis, Missouri 63110, USA.
authors.forename: Young
authors.initials: Y
authors.lastname: Sun
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Mochizuki
authors.forename: Philip W
authors.initials: PW
authors.lastname: Majerus
mesh_terms: D015703:Antigens, CD / Q000378:metabolism*; D017209:Apoptosis; D015152:Blotting, Northern; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases / Q000378:metabolism; D002460:Cell Line; D003513:Cycloheximide / Q000494:pharmacology; D004247:DNA / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005047:Etoposide / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000378:metabolism / Q000502:physiology*; D011065:Poly(ADP-ribose) Polymerases / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000378:metabolism*; D047888:Receptors, Tumor Necrosis Factor, Type I; D047990:TNF Receptor-Associated Factor 1; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
chemical_list: D015703:Antigens, CD; D011500:Protein Synthesis Inhibitors; D011506:Proteins; D018124:Receptors, Tumor Necrosis Factor; D047888:Receptors, Tumor Necrosis Factor, Type I; D047990:TNF Receptor-Associated Factor 1; D014409:Tumor Necrosis Factor-alpha; D005047:Etoposide; D004247:DNA; D003513:Cycloheximide; D011065:Poly(ADP-ribose) Polymerases; D017853:Phosphotransferases (Alcohol Group Acceptor); C056875:myo-inositol-trisphosphate 6-kinase; C505407:CASP3 protein, human; C505530:CASP8 protein, human; C506433:CASP9 protein, human; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9; D020169:Caspases