title: Bax conformational change is a crucial step for PUMA-mediated apoptosis in human leukemia.
abstract: The BH3-only protein, PUMA, plays an important role in p53-mediated apoptosis. The apoptotic effect of PUMA on the mitochondria was studied using a p53-negative, human leukemia K562 cell line. Overexpression of PUMA was accompanied by an increased Bax expression, Bax conformational change, and translocation to mitochondria. A PUMA-BH3 peptide can induce Bax conformational change, cytochrome c release, and reduction in the mitochondrial membrane potential (DeltaPsi(m)) in isolated K562 mitochondria and can be inhibited by Bcl-XL. The homo-dimer of Bax/Bax was also weakly shown after mitochondria were treated with PUMA-BH3 peptide but may not be lethal for PUMA-induced apoptosis in K562 cells. Our results suggest that PUMA-induced Bax conformational change and Bax translocation to mitochondria can be separate events and the conformational change in Bax is crucial for PUMA-induced mitochondrial dysfunction.
authors.affiliation: Department of Haematology, Barts and the London, Queen Mary's School of Medicine and Dentistry, University of London, London, UK.
authors.forename: Feng-Ting
authors.initials: FT
authors.lastname: Liu
authors.forename: Adrian C
authors.initials: AC
authors.lastname: Newland
authors.forename: Li
authors.initials: L
authors.lastname: Jia
mesh_terms: D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D015153:Blotting, Western; D045744:Cell Line, Tumor; D003432:Cross-Linking Reagents / Q000494:pharmacology; D045304:Cytochromes c / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D019281:Dimerization; D005434:Flow Cytometry; D006801:Humans; D020014:K562 Cells; D007938:Leukemia / Q000378:metabolism* / Q000473:pathology; D008564:Membrane Potentials; D051379:Mice; D008928:Mitochondria / Q000378:metabolism; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation; D021381:Protein Transport; D011506:Proteins / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000737:chemistry* / Q000378:metabolism; D019253:Proto-Oncogene Proteins c-bcl-2; D013347:Subcellular Fractions; D014162:Transfection; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D051028:bcl-2-Associated X Protein
chemical_list: D051017:Apoptosis Regulatory Proteins; C494826:BAX protein, human; C438378:BBC3 protein, human; C494827:Bax protein, mouse; D003432:Cross-Linking Reagents; D010455:Peptides; D011506:Proteins; D011518:Proto-Oncogene Proteins; D019253:Proto-Oncogene Proteins c-bcl-2; D016159:Tumor Suppressor Protein p53; D051028:bcl-2-Associated X Protein; D045304:Cytochromes c