Abstract
Thyroid hormone (TH) modulates metabolic efficiency by controlling the coupling of mitochondrial oxidative phosphorylation. However, its uncoupling mode of action is still enigmatic. Treatment of Jurkat or GH3 cells with T3 is reported here to result in limited, Cyclosporin A-sensitive mitochondrial depolarization, conforming to low conductance gating of the mitochondrial transition pore (MTP). MTP protein components induced by T3 treatment were verified in T3-treated and hypothyroid rat liver as well as in Jurkat cells. T3 treatment resulted in increase in mitochondrial Bax and Bak together with decreased mitochondrial Bcl2. T3-induced mitochondrial depolarization was aborted by overexpression of Bcl2. In contrast to Bax-Bcl2 family proteins, some other MTP components were either not induced by T3 (e.g. voltage-dependent anion channel) or were induced, but were not involved in Cyclosporin A-sensitive MTP gating (e.g. Cyclophilin D and adenine nucleotide translocase-2) Hence, TH-induced mitochondrial uncoupling may be ascribed to low conductance MTP gating mediated by TH-induced increase in mitochondrial proapoptotic combined with a decrease in mitochondrial antiapoptotic proteins of the Bax-Bcl2 family.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Animals
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Cyclophilins / analysis
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Cyclophilins / genetics
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Cyclosporine / pharmacology
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Gene Expression
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HeLa Cells
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Humans
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Hypothyroidism
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Intracellular Membranes / chemistry
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Intracellular Membranes / drug effects
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Intracellular Membranes / physiology
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Ion Channel Gating / drug effects
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Isoenzymes / analysis
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Isoenzymes / genetics
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Isoenzymes / physiology
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Jurkat Cells
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Male
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Membrane Potentials
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Membrane Proteins / analysis
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Mitochondria, Liver / chemistry*
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Mitochondria, Liver / drug effects
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Mitochondria, Liver / ultrastructure*
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Mitochondrial ADP, ATP Translocases / analysis
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Mitochondrial ADP, ATP Translocases / genetics
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Mitochondrial ADP, ATP Translocases / physiology
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Peptidyl-Prolyl Isomerase F
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Porins / analysis
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Porins / biosynthesis
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Porins / physiology
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Proto-Oncogene Proteins c-bcl-2 / analysis
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Rats
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Transfection
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Triiodothyronine / pharmacology*
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Voltage-Dependent Anion Channels
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bcl-2 Homologous Antagonist-Killer Protein
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bcl-2-Associated X Protein
Substances
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BAK1 protein, human
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BAX protein, human
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Bak1 protein, rat
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Bax protein, rat
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Peptidyl-Prolyl Isomerase F
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Isoenzymes
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Membrane Proteins
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Porins
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Proto-Oncogene Proteins c-bcl-2
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Voltage-Dependent Anion Channels
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bcl-2 Homologous Antagonist-Killer Protein
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bcl-2-Associated X Protein
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Triiodothyronine
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Cyclosporine
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Mitochondrial ADP, ATP Translocases
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Cyclophilins