Abstract
Alterations in intracellular Zn(2+) concentrations are believed to play a crucial role in modulating apoptosis. The observation that Zn(2+) deficiency can induce cell death both in vivo and in vitro has been attributed to the fact that exchange of Zn(2+) for Ca(2+) and Mg(2+) within the nuclei may directly activate endogenous endonucleases therefore inducing DNA fragmentation independent of cytoplasmic factors. Here we show that the membrane-permeable zinc chelator, N,N',N'-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) induces translocation of cytochrome c from the mitochondrial intramembranous space into the cytosol in human peripheral blood T lymphocytes (PBL) with subsequent activation of caspases-3, -8, and -9. Pretreatment of T lymphocytes with caspase inhibitors Z-VAD.fmk or DEVD.fmk prevented DNA fragmentation in response to TPEN indicating that apoptosis triggered by zinc deficiency is entirely dependent on activation of caspase family members. The release of cytochrome c and activation of downstream caspases precedes changes in the mitochondrial transmembrane potential (Delta Psim). Therefore, cytoplasmic and mitochondrial events are critical to this process.
Publication types
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Research Support, Non-U.S. Gov't
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Research Support, U.S. Gov't, P.H.S.
MeSH terms
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Amino Acid Chloromethyl Ketones / pharmacology
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Apoptosis*
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Blotting, Western
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Calcium / pharmacology
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases / metabolism
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Cells, Cultured
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Chelating Agents / pharmacology
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Cytochrome c Group / metabolism
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Cytoplasm / metabolism
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DNA Fragmentation
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Dose-Response Relationship, Drug
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Electrophoresis, Polyacrylamide Gel
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Enzyme Activation
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Enzyme Inhibitors / pharmacology
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Ethylenediamines / pharmacology
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Flow Cytometry
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Humans
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Immunohistochemistry
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Intracellular Membranes / metabolism
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Jurkat Cells
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Kinetics
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Magnesium / pharmacology
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Membrane Potentials
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Mitochondria / metabolism
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T-Lymphocytes / cytology
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T-Lymphocytes / metabolism
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T-Lymphocytes / pathology*
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Time Factors
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Zinc / deficiency*
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Zinc / metabolism
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fas Receptor / biosynthesis
Substances
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Amino Acid Chloromethyl Ketones
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Chelating Agents
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Cytochrome c Group
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Enzyme Inhibitors
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Ethylenediamines
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benzyloxycarbonylvalyl-alanyl-aspartyl fluoromethyl ketone
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fas Receptor
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CASP3 protein, human
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CASP8 protein, human
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CASP9 protein, human
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Caspase 3
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Caspase 8
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Caspase 9
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Caspases
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Magnesium
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Zinc
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N,N,N',N'-tetrakis(2-pyridylmethyl)ethylenediamine
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Calcium