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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Apoptosis Regulatory Proteins
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Apoptosis*
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Blotting, Western
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Cell Line, Tumor
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Cross-Linking Reagents / pharmacology
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Cytochromes c / metabolism
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Cytosol / metabolism
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Dimerization
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Flow Cytometry
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Humans
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K562 Cells
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Leukemia / metabolism*
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Leukemia / pathology
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Membrane Potentials
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Mice
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Mitochondria / metabolism
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Peptides / chemistry
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Protein Conformation
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Protein Transport
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Proteins / metabolism*
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Proto-Oncogene Proteins / chemistry*
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Proto-Oncogene Proteins / metabolism
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Proto-Oncogene Proteins c-bcl-2*
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Subcellular Fractions
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Transfection
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Tumor Suppressor Protein p53 / metabolism
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bcl-2-Associated X Protein
Substances
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Apoptosis Regulatory Proteins
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BAX protein, human
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BBC3 protein, human
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Bax protein, mouse
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Cross-Linking Reagents
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Peptides
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Proteins
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Proto-Oncogene Proteins
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Proto-Oncogene Proteins c-bcl-2
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Tumor Suppressor Protein p53
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bcl-2-Associated X Protein
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Cytochromes c