The Ku Antigen-Recombination Signal-binding Protein Jκ Complex Binds to the Nuclear Factor-κB p50 Promoter and Acts as a Positive Regulator of p50 Expression in Human Gastric Cancer Cells

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The p50 subunit of NF-κB is a transcription factor that regulates the expression of a variety of genes. Previously, we showed that the expression of Ku antigen, a DNA repair protein, is mediated by NF-κB in gastric cancer AGS cells (Lim, J. W., Kim, H., and Kim, K. H. (2002) J. Biol. Chem. 277, 46093–46100). In this study, we report that the inhibition of Ku activity reduced both p50 expression and nuclear NF-κB activity in AGS cells. A co-immunoprecipitation experiment demonstrated that Ku antigen interacted with recombination signal-binding protein Jκ (RBP-Jκ), a DNA-binding protein. Ku antigen, RBP-Jκ, and p50 were found to bind to the DNA region containing the κB element in the p50 promoter. Supershift and competition experiments demonstrated that Ku antigen and RBP-Jκ bound sequence-specifically to downstream elements of κB at GCTTC and TGGGGG. mRNA expression and de novo synthesis of p50 were inhibited in cells transfected with the mutant gene expression constructs for IκBα, Ku80, and RBP-Jκ. A reporter assay demonstrated that p50 transcription was positively mediated by NF-κB, Ku antigen, and RBP-Jκ and that the binding elements for these proteins were required for optimal p50 expression. The interaction of Ku antigen with RBP-Jκ and NF-κB p50 may act as a positive regulator of p50 expression in gastric cancer AGS cells. The p50 subunit of NF-κB is a transcription factor that regulates the expression of a variety of genes. Previously, we showed that the expression of Ku antigen, a DNA repair protein, is mediated by NF-κB in gastric cancer AGS cells (Lim, J. W., Kim, H., and Kim, K. H. (2002) J. Biol. Chem. 277, 46093–46100). In this study, we report that the inhibition of Ku activity reduced both p50 expression and nuclear NF-κB activity in AGS cells. A co-immunoprecipitation experiment demonstrated that Ku antigen interacted with recombination signal-binding protein Jκ (RBP-Jκ), a DNA-binding protein. Ku antigen, RBP-Jκ, and p50 were found to bind to the DNA region containing the κB element in the p50 promoter. Supershift and competition experiments demonstrated that Ku antigen and RBP-Jκ bound sequence-specifically to downstream elements of κB at GCTTC and TGGGGG. mRNA expression and de novo synthesis of p50 were inhibited in cells transfected with the mutant gene expression constructs for IκBα, Ku80, and RBP-Jκ. A reporter assay demonstrated that p50 transcription was positively mediated by NF-κB, Ku antigen, and RBP-Jκ and that the binding elements for these proteins were required for optimal p50 expression. The interaction of Ku antigen with RBP-Jκ and NF-κB p50 may act as a positive regulator of p50 expression in gastric cancer AGS cells. NF-κB is a transcription factor that regulates a wide variety of the genes that respond to immune or inflammatory signals (1.Baeuerle P.A. Baltimore D. Cell. 1996; 87: 13-20Abstract Full Text Full Text PDF PubMed Scopus (2931) Google Scholar). NF-κB is a member of the Rel family, which includes p50 (NF-κB1), p52 (NF-κB2), RelA (p65), and c-Rel and RelB (2.Siebenlist U. Franzoso G. Brown K. Annu. Rev. Cell Biol. 1994; 10: 405-455Crossref PubMed Scopus (2015) Google Scholar). In resting cells, NF-κB is localized in the cytoplasm as a hetero- or homodimer, which is noncovalently associated with cytoplasmic inhibitory proteins, including IκBα. Upon stimulation by a variety of pathogenic inducers such as viruses, mitogens, bacteria, and inflammatory cytokines, IκBα is degraded in the cytoplasm, allowing the NF-κB complex to migrate into the nucleus and to bind to a DNA recognition site in the regulatory regions of the target genes (3.Thanos D. Maniatis T. Cell. 1995; 80: 529-532Abstract Full Text PDF PubMed Scopus (1217) Google Scholar). Some stimuli, including phorbol ester, tumor necrosis factor, and platelet-activating factor, induce p50 mRNA expression (4.Meyer R. Hatada E.N. Hohmann H.P. Haiker M. Bartsch C. Rothlisberger U. Lahm H.W. Schlaeger E.J. van Loon A.P. Scheidereit C. Proc. Natl. Acad. Sci. U. S. A. 1991; 88: 966-970Crossref PubMed Scopus (157) Google Scholar, 5.Tan X. Sun X. Gonzalez-Crussi F.X. Gonzalez-Crussi F. Hsueh W. Biochim. Biophys. Acta. 1994; 1215: 157-162Crossref PubMed Scopus (41) Google Scholar). p50 expression in leukemia cells and in lung and skin cancer tissues is higher than that in their normal counterparts, suggesting that its expression may be related to tumor or cancer development (6.Mukhopadhyay T. Roth J.A. Maxwell S.A. Oncogene. 1995; 11: 999-1003PubMed Google Scholar, 7.Budunova I.V. Perez P. Vaden V.R. Spiegelman V.S. Slaga T.J. Jorcano J.L. Oncogene. 1999; 18: 7423-7431Crossref PubMed Scopus (112) Google Scholar, 8.Zhang M.S. Yuan H.Y. Xiong B. Deng Q. Tang Z.J. Xia D. Ai Zheng. 2002; 21: 1226-1230PubMed Google Scholar, 9.Inoue M. Matsuoka M. Yamaguchi K. Takatsuki K. Yoshida M. Jpn. J. Cancer Res. 1998; 89: 53-59Crossref PubMed Scopus (21) Google Scholar). It has been reported that p50 induction is partially mediated by members of the NF-κB family by binding the κB element in the p50 promoter (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar, 11.Schooley K. Zhu P. Dower K. Qwarnstrom E.E. Biochem. J. 2003; 369: 331-339Crossref PubMed Scopus (28) Google Scholar). However, comparatively little is known about the factors and signal transduction pathways that contribute to the regulation of p50 expression. Recombination signal-binding protein Jκ (RBP-Jκ) 1The abbreviations used are: RBP-Jκ, recombination signal-binding protein Jκ; RT, reverse transcription; EMSA, electrophoretic mobility shift assay. is a DNA-binding protein that participates in the control of both cytokine and NF-κB p52 protein expression (12.Honjo T. Genes Cells. 1996; 1: 1-9Crossref PubMed Scopus (181) Google Scholar, 13.Kannabiran C. Zeng X. Vales L.D. Mol. Cell. Biol. 1997; 17: 1-9Crossref PubMed Scopus (64) Google Scholar, 14.Krauer K.G. Belzer D.K. Liaskou D. Buck M. Cross S. Honjo T. Sculley T. Virology. 1998; 252: 418-430Crossref PubMed Scopus (19) Google Scholar, 15.Oswald F. Liptay S. Adler G. Schmid R.M. Mol. Cell. Biol. 1998; 18: 2077-2088Crossref PubMed Google Scholar, 16.Fennewald S.M. Aronson J.F. Zhang L. Herzog N.K. J. Virol. 2002; 76: 1154-1162Crossref PubMed Scopus (37) Google Scholar). Several genes known to be repressed or activated by RBP-Jκ possess a κB element containing overlapping NF-κB- and RBP-Jκ-binding elements in their promoter regions (12.Honjo T. Genes Cells. 1996; 1: 1-9Crossref PubMed Scopus (181) Google Scholar, 13.Kannabiran C. Zeng X. Vales L.D. Mol. Cell. Biol. 1997; 17: 1-9Crossref PubMed Scopus (64) Google Scholar, 14.Krauer K.G. Belzer D.K. Liaskou D. Buck M. Cross S. Honjo T. Sculley T. Virology. 1998; 252: 418-430Crossref PubMed Scopus (19) Google Scholar, 15.Oswald F. Liptay S. Adler G. Schmid R.M. Mol. Cell. Biol. 1998; 18: 2077-2088Crossref PubMed Google Scholar, 16.Fennewald S.M. Aronson J.F. Zhang L. Herzog N.K. J. Virol. 2002; 76: 1154-1162Crossref PubMed Scopus (37) Google Scholar). Therefore, there is a possibility of interplay between NF-κB and RBP-Jκ for binding to the κB element in the p50 promoter. Ku antigen, a heterodimer of Ku70 and Ku80, is the regulatory DNA-binding region of DNA-dependent protein kinase, which has been implicated in several nuclear processes, including DNA double strand break repair and V(D)J recombination (17.Sawaoka H. Kawano S. Tsuji S. Tsujii M. Gunawan E.S. Takei Y. Nagano K. Hori M. Am. J. Physiol. 1998; 274: G1061-G1067PubMed Google Scholar, 18.Battu S. Rigaud M. Beneytout J.L. Anticancer Res. 1998; 18: 3579-3583PubMed Google Scholar, 19.Erickson B.A. Longo W.E. Panesar N. Mazuski J.E. Kaminski D.L. J. Surg. Res. 1999; 81: 101-107Abstract Full Text PDF PubMed Scopus (77) Google Scholar). Ku antigen possess a strong for DNA and for DNA such as and T. J.A. J. Biol. Chem. Full Text PDF PubMed Google Scholar, M. J. Biol. Chem. 1994; Full Text PDF PubMed Google Scholar, S. H. W. W. C. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar, S. Res. 1998; PubMed Scopus Google in a J. A. Res. 1998; PubMed Scopus Google Scholar, N. N. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, M. G. M. L. G. R. R. A. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, J. Biol. Chem. Full Text PDF PubMed Google Scholar, A.P. N. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, L. J.F. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus (37) Google Scholar). Ku binding elements been in variety of genes such as and J. A. Res. 1998; PubMed Scopus Google Scholar, N. N. J. Biol. Chem. 1996; Full Text Full Text PDF PubMed Scopus Google Scholar, M. G. M. L. G. R. R. A. J. Biol. Chem. Full Text Full Text PDF PubMed Scopus Google Scholar, J. Biol. Chem. Full Text PDF PubMed Google Scholar, A.P. N. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, L. J.F. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus (37) Google and Ku antigen has been to be in the positive or regulation of these genes. Oncogene. PubMed Scopus Google showed that the of Ku antigen nuclear NF-κB activity in Therefore, NF-κB subunit expression and NF-κB activity be by the Ku antigen expression in cells. we that Ku antigen regulates the expression of the NF-κB p50 subunit and with RBP-Jκ. that Ku antigen, RBP-Jκ, and NF-κB p50 associated with the DNA region that the κB element in the p50 promoter and that these proteins positively p50 expression. we that the interaction of Ku antigen with RBP-Jκ and NF-κB p50 as a positive regulator of p50 expression in gastric cancer AGS cells. Cell and gastric cancer AGS cells were in with Ku cells and and cells, as H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google were AGS cells transfected with a mutant gene containing a and with a control expression and cells were in containing and were as H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). were the assay was as H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). of was to and to by binding with were with and at The proteins were to by was used as a p50 and were mRNA expression was by the gene as the cells was into and used for with for p50 and The of the p50 used were and a M. F. J. F. Le Bail O. Kourilsky P. P.A. Israel A. Cell. Full Text PDF PubMed Scopus Google Scholar). The were and a S. H. P. T. Proc. Natl. Acad. Sci. U. S. A. PubMed Scopus Google Scholar). p50 and these by the were containing and by were by the reverse reverse was to the the for the of cells or of cells transfected with Ku or mutant genes for RBP-Jκ, IκBα, and and novo synthesis and mRNA of p50 in AGS cells transfected with RBP-Jκ or mutant genes for RBP-Jκ, and cells or cells transfected with constructs control or mutant genes for IκBα, RBP-Jκ, and were with and p50 was with The is of The of p50 de novo in cells was to be were the cells, and p50 mRNA were by The p50 were and the the reverse control reverse was to the the for the of cells or of cells transfected with or mutant genes for RBP-Jκ, IκBα, and The of was to be the of was the B. Res. PubMed Scopus Google with a of or nuclear of were with of p50 in of and of of containing a binding element was and with the of DNA and NF-κB was a NF-κB containing the element of the was a in the was and to at the competition nuclear were with of for to the the nuclear were with of for to the experiment with proteins binding to the p50 promoter. of cells were for with of and by p50 The a p50 experiment with proteins binding to the p50 promoter. of cells were for with the for RBP-Jκ, or and by with and the p50 activity in the nuclear The a p50 activity of p50 in AGS cells transfected with RBP-Jκ or mutant genes for RBP-Jκ, and and nuclear were cells or cells transfected with the constructs control or mutant genes for IκBα, RBP-Jκ, and The binding activity of p50 was a p50 The a p50 activity in AGS cells transfected with the mutant and nuclear were cells and cells transfected with the control or the mutant gene and NF-κB activity was a NF-κB the nuclear were with or and to the NF-κB activity in the nuclear The NF-κB AGS cells, Ku cells and and cells were in of assay and and at for and protein were to the and the was at The protein complex was by with assay The was in of and for was to for the was by and into the in for mutant was by a O. H.P. U. PubMed Scopus Google which a site The reporter was by a of the NF-κB promoter to into the site of the (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar). and were by in and and cells were in at a of in of and transfected with of RBP-Jκ or mutant genes for RBP-Jκ, IκBα, and for RBP-Jκ and mutant RBP-Jκ were as The IκBα mutant gene is IκBα gene at and to NF-κB H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google and the mutant gene a cells were transfected with a control expression and cytoplasmic were and used in the experiment the de novo synthesis of p50 and in for NF-κB cells were with the expression of as a control to and the cells were for and the assay to the activity was to activity in and cells or cells transfected with or mutant genes for RBP-Jκ, IκBα, and were in and containing for and with for The cells were in assay and with of were with and protein at The protein complex was with assay The proteins were by and the was to at The of p50 de novo in cells was to be DNA with p50 and NF-κB is known to with the heterodimer by Ku70 and the was found to be to bind which DNA binding activity N. M. S. J. J. P. Res. PubMed Scopus Google Scholar, O. P. K. Biochem. Biophys. Res. 1999; PubMed Scopus Google Scholar, X. Mol. Cell. Biol. 1996; PubMed Scopus Google Scholar, F. D. Res. 1998; PubMed Scopus (41) Google Scholar). showed that AGS cells transfected with the mutant gene containing the and DNA binding activity than cells transfected with a control H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). we that the protein of in and cells were than in and cells, the and RBP-Jκ protein in these cells The protein of p50 and were The p50 mRNA were in and cells than in and cells p50 and mRNA were in the reverse NF-κB activity in these cells, we a NF-κB containing a NF-κB in and cells were than in and cells A experiment the nuclear showed that the NF-κB was by and that the NF-κB in the nuclear is a p50 and that Ku antigen activity may be associated with p50 expression and nuclear NF-κB activity in AGS cells. In cytoplasmic a in the NF-κB by was in and cells and cells The NF-κB was as a p50 The of a p50 was to a which has been reported to bind to the NF-κB (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar, 11.Schooley K. Zhu P. Dower K. Qwarnstrom E.E. Biochem. J. 2003; 369: 331-339Crossref PubMed Scopus (28) Google Scholar). The was to protein bound to the NF-κB which Ku RBP-Jκ, and NF-κB p50 to the κB in the p50 κB element in the NF-κB p50 promoter is for p50 expression in cells in to tumor necrosis factor and phorbol of this element to a in promoter activity in cells (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar, C.V. R.M. C. J. Virelizier J.L. Proc. Natl. Acad. Sci. U. S. A. 1992; 89: PubMed Scopus Google Scholar). we κB element binding activity in the p50 promoter is associated with Ku antigen activity AGS cells, Ku cells and and cells. κB element binding in the p50 promoter in both cytoplasmic and nuclear of and cells were than in cytoplasmic and nuclear of and cells as by the p50 containing the κB element of the p50 promoter at to (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar). that Ku antigen activity is associated with κB element binding activity in the p50 promoter. The bound to the κB element in the p50 in the cytoplasmic was to be a heterodimer of the heterodimer to the κB element in the p50 promoter has been reported (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar, 11.Schooley K. Zhu P. Dower K. Qwarnstrom E.E. Biochem. J. 2003; 369: 331-339Crossref PubMed Scopus (28) Google Scholar). the binding of Ku antigen and RBP-Jκ to the κB element in the p50 we a experiment in which and were used to shift the The p50 was found to be by and by Therefore, the NF-κB p50 homodimer, RBP-Jκ, and Ku antigen were found to be to bind to the p50 containing the κB Ku with is known to gene expression by with several proteins, of and and H.Y. P. N. Tang M. R.M. T. Genes 1998; PubMed Scopus Google Scholar, F. U. K. S. K. U. L. M. H. W. Liptay S. Schmid R.M. EMBO J. 2002; 21: PubMed Scopus Google Scholar). the possibility of p50 expression induction to binding between RBP-Jκ and Ku antigen a co-immunoprecipitation were with or and were to with RBP-Jκ was in the and the of RBP-Jκ that with Ku70 and was in and cells than in and cells. a Ku70 and were in and the by RBP-Jκ were found to be in and cells than in and cells. that Ku antigen with RBP-Jκ and that the by the mutant gene Ku p50 with the Ku and NF-κB p50 Ku antigen, RBP-Jκ, and NF-κB p50 bind to the κB element in the p50 containing the binding elements for Ku antigen, RBP-Jκ, and NF-κB were and used as The and the binding elements for NF-κB and RBP-Jκ, R. Baltimore D. Cell. Full Text PDF PubMed Scopus Google Scholar, T. Y. N. T. Honjo T. M. Res. 1994; PubMed Scopus Google Scholar). The Ku antigen was used to DNA binding activity Ku antigen this H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, B. Res. PubMed Scopus Google Scholar). of nuclear the p50 as a showed that the p50 was by the and Ku antigen suggesting that Ku antigen, RBP-Jκ, and NF-κB p50 were in the complex we a into the p50 to the binding elements for these The element site of p50 is known to be (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar). The RBP-Jκ-binding elements in the p50 promoter overlapping the site and and The mutant to the and binding elements were and The double mutant for both NF-κB and was that for both NF-κB and was The p50 was found to be by the and Therefore, we experiments the mutant as in RBP-Jκ was found to bind to the binding to the binding as were with in the and as the and were that RBP-Jκ to the of the κB element in the p50 which with the RBP-Jκ is known to bind to DNA J. Virol. 1994; PubMed Google Scholar). However, the RBP-Jκ-binding element in the p50 promoter has a TGGGGG. the promoter regions in a of genes were found to RBP-Jκ-binding elements T. G. Y. L. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). Therefore, RBP-Jκ-binding and RBP-Jκ binding found that RBP-Jκ DNA binding activity was reduced by Ku antigen DNA binding suggesting that the between Ku and RBP-Jκ may contribute to RBP-Jκ binding to this in the p50 promoter. NF-κB binding to the element as by was by in the and as the and were used which is with reported (10.Ten R.M. Paya C.V. Israel N. Le Bail O. Mattei M.G. Virelizier J.L. Kourilsky P. Israel A. EMBO J. 1992; 11: 195-203Crossref PubMed Scopus (207) Google Scholar). the p50 in mutant were suggesting that NF-κB in the nuclear protein of AGS cells as a p50 Therefore, the NF-κB p50 and RBP-Jκ bind to the κB element in the p50 promoter. However, the p50 was with the Ku antigen and was by and in experiments the and and that Ku antigen may bind to the NF-κB- and RBP-Jκ-binding to DNA region in the p50 promoter. the Ku we into the region of the as the as as The p50 was by the and by the and Therefore, the binding element for Ku antigen in the p50 promoter is the which the NF-κB- and RBP-Jκ-binding elements and the Ku element in the p50 with the p50 suggesting that Ku antigen bind to the p50 promoter NF-κB and RBP-Jκ binding to this Ku RBP-Jκ, and NF-κB p50 p50 and RBP-Jκ regulates p50 AGS cells were transfected with constructs for RBP-Jκ or its mutant gene which RBP-Jκ which to DNA J. 1995; PubMed Scopus Google Scholar). transfected the cells with constructs for the and IκBα mutant which were reported to NF-κB and Ku DNA binding activity H. 81: PubMed Scopus Google Scholar). de novo protein synthesis and the mRNA expression of p50 were the of p50 de cells were transfected with these constructs and to with of p50 protein in were by with and with mutant genes for IκBα, RBP-Jκ, and the de novo synthesis of p50 p50 mRNA were reduced in the cells transfected with these constructs that NF-κB, RBP-Jκ, and Ku antigen positively p50 expression. However, p50 expression was reduced in cells RBP-Jκ this in the of synthesis and the mRNA of p50 were than in cells transfected with mutant genes for IκBα, RBP-Jκ, and A and in and gastric cancer AGS cells of NF-κB and RBP-Jκ, and Therefore, the expression of RBP-Jκ may the of NF-κB, RBP-Jκ, and Ku antigen, in reduced p50 expression. be p50 expression in gastric cells containing of NF-κB, RBP-Jκ, and Ku with mutant genes for IκBα, RBP-Jκ, and DNA binding activity cells transfected with the control these proteins p50 the containing the p50 promoter was with constructs RBP-Jκ and the mutant genes for IκBα, RBP-Jκ, and The of the constructs mutant genes for IκBα, RBP-Jκ, and in a of activity that NF-κB, RBP-Jκ, and Ku antigen positively p50 to reduced p50 expression in cells RBP-Jκ in the of the RBP-Jκ repressed of p50 transcription by with the RBP-Jκ may be by with complex between NF-κB, Ku antigen, and RBP-Jκ in gastric cancer AGS cells containing of RBP-Jκ. the of DNA-binding element in p50 gene reporter constructs containing these binding elements were and transfected into AGS cells. The and reporter constructs DNA-binding elements for RBP-Jκ, NF-κB and RBP-Jκ, The reporter DNA-binding elements for both NF-κB and RBP-Jκ. However, the reporter DNA-binding elements for these and and Ku were In the and reporter constructs were than the reporter that and Ku elements required for p50 expression. NF-κB activity is known to be by the of Ku antigen in Oncogene. PubMed Scopus Google suggesting that the expression of NF-κB may be related to Ku antigen In this study, the inhibition of Ku antigen activity by with a expression gene was found to the expression of p50 of in gastric cancer AGS cells. of the expression gene was found to nuclear NF-κB RBP-Jκ is in p50 expression p50 expression is mediated by the κB element in the p50 promoter and RBP-Jκ to several κB elements in the NF-κB p50 promoter and regulates gene expression. RBP-Jκ with several proteins, including and and regulates their gene expression H.Y. P. N. Tang M. R.M. T. Genes 1998; PubMed Scopus Google Scholar, F. U. K. S. K. U. L. M. H. W. Liptay S. Schmid R.M. EMBO J. 2002; 21: PubMed Scopus Google Scholar). a of Ku antigen as a protein. RBP-Jκ was found to bind to the of the κB element in the p50 which with the RBP-Jκ has been to bind to DNA J. Virol. 1994; PubMed Google Scholar). However, the p50 promoter has a to which RBP-Jκ as by regions in a of genes RBP-Jκ-binding RBP-Jκ to a in the promoter T. G. Y. L. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). Therefore, the RBP-Jκ-binding is and RBP-Jκ binding In this study, RBP-Jκ DNA binding activity was reduced by inhibition of Ku antigen that between Ku antigen and RBP-Jκ to RBP-Jκ binding to this In this study, we found that Ku antigen bound downstream of the κB element in the p50 promoter. A competition experiment with mutant the Ku The Ku in this the reported as a Ku J. 1995; PubMed Scopus Google Scholar). the Ku has been be to the Ku and the de novo synthesis of p50 showed that p50 expression was reduced by the DNA binding of NF-κB, RBP-Jκ, and Ku gene demonstrated that p50 transcription was by the DNA binding of NF-κB, RBP-Jκ, and Ku antigen or by these that Ku antigen, RBP-Jκ, or NF-κB positively regulates p50 expression in gastric cancer AGS cells. However, the of RBP-Jκ or of the mutant gene of RBP-Jκ reduced the expression and transcription of p50 and its DNA binding Therefore, the expression of RBP-Jκ is for optimal p50 expression. In we found that Ku antigen as a regulator of transcription by with RBP-Jκ and the NF-κB p50 to p50 expression in gastric cancer AGS cells. that p50 expression is related to the and of of cells (6.Mukhopadhyay T. Roth J.A. Maxwell S.A. Oncogene. 1995; 11: 999-1003PubMed Google Scholar, 7.Budunova I.V. Perez P. Vaden V.R. Spiegelman V.S. Slaga T.J. Jorcano J.L. Oncogene. 1999; 18: 7423-7431Crossref PubMed Scopus (112) Google Scholar, 8.Zhang M.S. Yuan H.Y. Xiong B. Deng Q. Tang Z.J. Xia D. Ai Zheng. 2002; 21: 1226-1230PubMed Google Scholar, 9.Inoue M. Matsuoka M. Yamaguchi K. Takatsuki K. Yoshida M. Jpn. J. Cancer Res. 1998; 89: 53-59Crossref PubMed Scopus (21) Google and that p50 and Ku antigen in and H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar, Y. Zhu C. van N. L. K. P. M.S. Roth 1997; Full Text Full Text PDF PubMed Scopus Google Scholar, H. 81: PubMed Scopus Google Scholar, Le M. F. Cell. PubMed Scopus Google Scholar, G. C. Proc. Natl. Acad. Sci. U. S. A. 2002; PubMed Scopus Google Scholar). Previously, we showed that gastric associated with be associated with both the and nuclear of Ku70 and a mediated by NF-κB in gastric cancer AGS cells H. J. Biol. Chem. 2002; Full Text Full Text PDF PubMed Scopus Google Scholar). that Ku antigen and NF-κB, by signals associated with and may p50 expression and nuclear NF-κB be to Ku antigen activity and p50 expression in the regulation of and