title: Study on the expression of IkappaB-alpha protein in TNF-alpha induced apoptosis of U937 cells.
abstract: OBJECTIVE
  To investigate the TNF-alpha induced apoptosis of U937 cells, the expression, degradation and subcellular localization of IkappaB-alpha, and its degradation mechanism.
  
  
  METHODS
  Changes and subcellular loca-lization of IkappaB-alpha were observed by fluorescence microscopy, expression and degradation of IkappaB-alpha protein with N-tosyl-L-phenylalanylchloromethyl ketone (TPCK protease inhibitor) blocking test and apoptosis of U937 cell by flow cytometry.
  
  
  RESULTS
  (1) immunolfluorescence assay showed that IkappaB-alpha localized in cytoplasm only. (2) The level of IkappaB-alpha protein was downregulated after TNF-alpha stimulation, flow cytometry also confirmed the downregulation. (3) The downregulation of IkappaB-alpha protein levels in TNF-alpha induced apoptosis was partially inhibited by TPCK. (4) The apoptosis rate of U937 cells induced by TNF-alpha was (60.73 +/- 1.61)%.
  
  
  CONCLUSIONS
  (1) Degradation of IkappaB-alpha protein during TNF-alpha induced apoptosis of U937 cells suggested the activation of NF-kappaB. (2) TPCK sensitive protease plays an important role in the degradation of IkappaB-alpha protein. (3) TPCK sensitive protease also involved in the apoptosis of U937 cells induced by TNF-alpha.
authors.affiliation: Department of Pediatrics, Tongji Hospital, Tongji Medical College of Huazhong University of Science and Technology, Wuhan 430030, China.
authors.forename: Weihua
authors.initials: W
authors.lastname: Chen
authors.forename: Guangjie
authors.initials: G
authors.lastname: Peng
authors.forename: Aiping
authors.initials: A
authors.lastname: Tang
authors.forename: Kaiyan
authors.initials: K
authors.lastname: Wang
authors.forename: Muxiang
authors.initials: M
authors.lastname: Zhou
authors.forename: Lingyi
authors.initials: L
authors.lastname: Wang
mesh_terms: D017209:Apoptosis / Q000187:drug effects; D015536:Down-Regulation; D006801:Humans; D016328:NF-kappa B / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism; D020298:U937 Cells
chemical_list: D016328:NF-kappa B; D014409:Tumor Necrosis Factor-alpha