Abstract
We previously established Fas-resistant variant clones from the human T-cell leukemia lines Jurkat and SUP-T13. Comparative gene expression analysis of the Fas-resistant and Fas-sensitive clones revealed several genes that were aberrantly expressed in the Fas-resistant clones. One of the genes, esophageal cancer-related gene 4 (ECRG4), contained a VDAC2-like domain that might be associated with apoptotic signals. In the present study, we examined the subcellular localization and function of ECRG4 in Fas-mediated apoptosis. By confocal fluorescence microscopy, ECRG4-EGFP fusion protein was detected in mitochondria, endoplasmic reticulum and the Golgi apparatus in gene-transfected HeLa cells. Overexpression of ECRG4 in Fas-sensitive Jurkat cells inhibited mitochondrial membrane permeability transition, leading to resistance against Fas-induced apoptosis. Tumor necrosis factor-alpha-induced apoptosis was also suppressed in ECRG4-overexpressing Jurkat cells. Immunoprecipitation assay demonstrated that ECRG4 is associated with procaspase-8. The inhibitory mechanism included the inhibition of caspase-8 activity and Bid cleavage. Since ECRG4 expression is downregulated in activated T cells, our results suggest that ECRG4 is a novel antiapoptotic gene which is involved in the negative regulation of caspase-8-mediated apoptosis in T cells.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Apoptosis / physiology*
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BH3 Interacting Domain Death Agonist Protein / genetics
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BH3 Interacting Domain Death Agonist Protein / metabolism
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Caspase 8 / genetics
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Caspase 8 / metabolism*
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Cell Line, Tumor
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Cell Membrane Permeability / genetics
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Down-Regulation
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Endoplasmic Reticulum / genetics
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Endoplasmic Reticulum / metabolism
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Fas-Associated Death Domain Protein / genetics
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Fas-Associated Death Domain Protein / metabolism
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Golgi Apparatus / genetics
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Golgi Apparatus / metabolism
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Green Fluorescent Proteins / genetics
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Green Fluorescent Proteins / metabolism
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HEK293 Cells
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HeLa Cells
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Humans
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Jurkat Cells
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Leukemia-Lymphoma, Adult T-Cell / genetics
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Leukemia-Lymphoma, Adult T-Cell / metabolism*
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Leukemia-Lymphoma, Adult T-Cell / pathology*
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Mitochondria / genetics
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Mitochondria / metabolism
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Neoplasm Proteins / genetics
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Neoplasm Proteins / metabolism*
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Recombinant Fusion Proteins / genetics
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Recombinant Fusion Proteins / metabolism
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T-Lymphocytes / metabolism
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Transfection / methods
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Tumor Necrosis Factor-alpha / genetics
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Tumor Necrosis Factor-alpha / metabolism
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Tumor Suppressor Proteins
Substances
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BH3 Interacting Domain Death Agonist Protein
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BID protein, human
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ECRG4 protein, human
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Fas-Associated Death Domain Protein
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Neoplasm Proteins
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Recombinant Fusion Proteins
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Tumor Necrosis Factor-alpha
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Tumor Suppressor Proteins
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enhanced green fluorescent protein
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Green Fluorescent Proteins
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Caspase 8