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Inhibition of nuclear translocation of transcription factor nuclear factor‐κB induces FAS‐ as well as tumour necrosis factor‐α‐mediated apoptosis through downregulation of a conserved family of inhibitor of apoptosis 1
Author(s) -
Imanishi Toshio,
Hano Takuzo,
Takarada Shigeho,
Nishio Ichiro
Publication year - 2003
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1046/j.1440-1681.2003.03817.x
Subject(s) - apoptosis , biology , programmed cell death , transcription factor , microbiology and biotechnology , tumor necrosis factor alpha , dna fragmentation , blot , downregulation and upregulation , immunology , biochemistry , gene
Summary 1. In the present study, we examined whether the nuclear transcription factor (NF)‐κB activity plays a role in the determination of sensitivity to tumour necrosis factor (TNF)‐α or agonistic Fas antibody (Ab) in human vascular smooth muscle cells (hVSMC). 2. To inhibit agonist‐induced NF‐κB activation in hVSMC, a cell‐permeable peptide (SN50), which carried the nuclear localization sequence of the NF‐κB p50 subunit, was used. Nuclear factor‐κB activity was examined by both immunoblot analysis of nuclear extracts and by ELISA. The hVSMC were treated with TNF‐α or agonistic Fas Ab (CH11) and then apoptosis was determined by cell death ELISA for DNA fragmentation. To investigate the mechanisms for protection against apoptosis in hVSMC, we analysed the expression of a conserved family of inhibitor of apoptosis 1 (c‐IAP1) protein using immunoblot analysis. 3. Although both CH11 and TNF‐α alone failed to induce hVSMC death in the presence of SN50, they markedly increased the apoptotic hVSMC estimated by cell death ELISA. In addition, these effects could be blocked with the pan‐caspase inhibitor z‐VAD.fmk. Western blotting analysis indicated that TNF‐α alone increased c‐IAP1 protein levels, whereas CH11 alone had no effect. Inhibition of NF‐κB activation by SN50 suppressed c‐IAP1 protein expression and enhanced apoptosis induced by either TNF‐α or CH11. 4. These findings suggest that c‐IAP1 is an important intracellular modulator of Fas as well as TNF‐α death signalling pathways in hVSMC. The expression of c‐IAP1 is regulated by a NF‐κB‐mediated phenomenon.