1. Overexpression of truncated I kappa B alpha potentiates TNF-alpha-induced apoptosis in mesangial cells
- Author
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J, Hirahashi, A, Takayanagi, K, Hishikawa, O, Takase, A, Chikaraishi, M, Hayashi, N, Shimizu, and T, Saruta
- Subjects
Caspase 8 ,Caspase 3 ,Tumor Necrosis Factor-alpha ,Genetic Vectors ,NF-kappa B ,Apoptosis ,Caspase 9 ,Peptide Fragments ,Adenoviridae ,Glomerular Mesangium ,Rats ,Proto-Oncogene Proteins c-bcl-2 ,Caspases ,Proto-Oncogene Proteins ,Animals ,I-kappa B Proteins ,Cells, Cultured ,bcl-2-Associated X Protein - Abstract
Dysregulation of apoptosis is one of the likely underlying mechanisms of mesangial proliferative glomerulonephritis (GN), a disease in which proinflammatory cytokines exhibit a wide range of biological activities. Among them, tumor necrosis factor-alpha (TNF-alpha) induces two conflicting pathways, one leading to activation of the nuclear factor-kappa B (NF-kappa B), and the other leading to caspase-mediated apoptosis. We investigated whether or not specific inhibition of NF-kappa B affects TNF-alpha-induced apoptosis in rat mesangial cells (MCs).To specifically inhibit NF-kappa B activation, we constructed a recombinant adenovirus vector expressing a truncated form of I kappa B alpha (AdexI kappa B delta N) that lacks the phosphorylation sites essential for the activation of NF-kappa B. Electrophoretic mobility shift assay was performed to evaluate NF-kappa B activity. Nuclear morphology was observed by staining with Hoechst-33258. DNA fragmentation was detected using an ELISA kit with an antihistone antibody. To investigate the regulation of apoptosis, we measured caspase-3 and caspase-8 activity by ELISA, and examined the Bcl-2 and Bax protein level by Western blot.TNF-alpha-induced NF-kappa B activation was blocked by overexpression of I kappa B delta N. Overexpression of I kappa B delta N potentiated TNF-alpha-induced apoptosis compared to mock transfection, and the potentiation was abolished by treatment with a caspase-3 inhibitor, Z-DEVD-FMK. Overexpression of I kappa B delta N augmented TNF-alpha-induced caspase-3 and caspase-8 activity, but did not affect Bcl-2 or Bax protein expression.Overexpression of I kappa B delta N potentiates TNF-alpha-induced apoptosis and augments caspase-8 and caspase-3 activity in rat MCs without changing Bcl-2 or Bax protein expression. These results suggest the potential usefulness of AdexI kappa B delta N to induce apoptosis in MCs under inflammatory conditions.
- Published
- 2000