Nuclear responses to depletion of mitochondrial DNA in human cells

Li, K.; Neufer, P. Darrell; Williams, R. Sanders

doi:10.1152/ajpcell.1995.269.5.c1265

Cited by 59 publications

(35 citation statements)

References 17 publications

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“…Our work showing that nine nuclear genes coding for major subunits of the five OXPHOS complexes are normally transcribed in cells fully depleted of mtDNA is consistent with the above reports. However, the results of Li et al (1995) partly disagree with ours and support the transcriptional coordination model. These investigators found that in 0 cells, the steady-state amount of transcript coding for the ␤ATPase measured by Northern blot analyses was unchanged in comparison to control cells, but that the amounts of CoIV and CoVIaL transcripts were increased by 60% and 100%.…”

Section: Discussioncontrasting

confidence: 85%

Large Functional Range of Steady-State Levels of Nuclear and Mitochondrial Transcripts Coding for the Subunits of the Human Mitochondrial OXPHOS System

Duborjal¹,

Beugnot²,

Camaret³

et al. 2002

Genome Res.

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We have measured, by reverse transcription and real-time quantitative PCR, the steady-state levels of the mitochondrial and nuclear transcripts encoding several subunits of the human oxidative phosphorylation (OXPHOS) system, in different normal tissues (muscle, liver, trachea, and kidney) and in cultured cells (normal fibroblasts, 143B osteosarcoma cells, 143B206 0 cells). Five mitochondrial transcripts and nine nuclear transcripts were assessed. The measured amounts of these OXPHOS transcripts in muscle samples corroborated data obtained by others using the serial analysis of gene expression (SAGE) method to appraise gene expression in the same type of tissue. Steady-state levels for all the transcripts were found to range over more than two orders of magnitude. Most of the time, the mitochondrial H-strand transcripts were present at higher levels than the nuclear transcripts. The mitochondrial L-strand transcript ND6 was usually present at a low level. Cultured 143B cells contained significantly reduced amounts of mitochondrial transcripts in comparison with the tissue samples. In 143B206 0 cells, fully depleted of mitochondrial DNA, the levels of nuclear OXPHOS transcripts were not modified in comparison with the parental cells. This observation indicated that nuclear transcription is not coordinated with mitochondrial transcription. We also observed that in the different tissues and cells, there is a transcriptional coregulation of all the investigated nuclear genes. Nuclear OXPHOS gene expression seems to be finely regulated.[The following individual kindly provided reagents, samples, or unpublished information as indicated in the paper: G. Attardi.]Through the process of oxidative phosphorylation (OXPHOS), mitochondria provide most of the ATP to eukaryotic cells. Oxidative phosphorylation corresponds to the terminal stage of substrate oxidation in mitochondria, and is catalyzed by the OXPHOS system, which functionally associates the mitochondrial respiratory chain, composed of four complexes (complexes I, II, III, and IV), and ATP synthase (complex V) for ATP synthesis. The biogenesis of all these enzymatic complexes, except complex II, requires expression of genes located at the level of both the nuclear and the mitochondrial genomes. Mechanisms that putatively coordinate the expression of these genes are poorly understood at present.

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Section: Discussioncontrasting

confidence: 85%

Large Functional Range of Steady-State Levels of Nuclear and Mitochondrial Transcripts Coding for the Subunits of the Human Mitochondrial OXPHOS System

Duborjal¹,

Beugnot²,

Camaret³

et al. 2002

Genome Res.

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“…Therefore, the ␣ and ␤ subunit precursors were imported in °cells, and their signal sequences were normally processed in the mitochondria. Previous studies have already shown that the °143B cells contained the same amount of F1 ␤ subunit mRNA as that of the parent ϩ cells, whereas the relative abundance of some other transcripts encoding mitochondrial proteins such as cytochrome c, cytochrome oxidase subunit IV and VIaL, and ANT 2 and ANT 3 were slightly more abundant (27). Doxycline-induced inhibition of mitochondrial protein synthesis in human leukemia cells also decreased the contents of complex III or complex IV subunits of nuclear origin without modifying that of the F1-ATPase ␣ and ␤ subunits during two culture generations (10).…”

Section: Discussionmentioning

confidence: 82%

Functional F1-ATPase Essential in Maintaining Growth and Membrane Potential of Human Mitochondrial DNA-depleted ρ° Cells

Buchet

Godinot

1998

Journal of Biological Chemistry

219

175

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F1-ATPase assembly has been studied in human °c ells devoid of mitochondrial DNA (mtDNA). Since, in these cells, oxidative phosphorylation cannot provide ATP, their growth relies on glycolysis. Despite the absence of the mtDNA-coded F0 subunits 6 and 8, °cells possessed normal levels of F1-ATPase ␣ and ␤ subunits. This F1-ATPase was functional and azide-or aurovertinsensitive but oligomycin-insensitive. In addition, aurovertin decreased cell growth in °cells and also reduced their mitochondrial membrane potential, as measured by rhodamine 123 fluorescence. Therefore, a functional F1-ATPase was important to maintain the mitochondrial membrane potential and the growth of these °c ells. Bongkrekic acid, a specific adenine nucleotide translocator (ANT) inhibitor, also reduced °cell growth and mitochondrial membrane potential. In conclusion, °cells need both a functional F1-ATPase and a functional ANT to maintain their mitochondrial membrane potential, which is necessary for their growth. ATP hydrolysis catalyzed by F1 must provide ADP 3؊ at a sufficient rate to maintain a rapid exchange with the glycolytic ATP 4؊ by ANT, this electrogenic exchange inducing a mitochondrial membrane potential efficient enough to sustain cell growth. However, since the effects of bongkrekic acid and of aurovertin were additive, other electrogenic pumps should cooperate with this pathway.The biogenesis of mitochondrial proteins is controlled by both nuclear and mitochondrial genomes. The proteins coded by the mtDNA are subunits of enzyme complexes involved in oxidative phosphorylation. Since all these complexes also contain proteins coded by the nuclear genome, mechanisms regulating the coordinated expression and assembly of the subunits of nuclear and mitochondrial origin must exist. In yeast cells, nuclear DNA-coded components continue to be synthesized and imported into mitochondria, even when the synthesis of mtDNA-coded subunits is blocked (cf. for review, Refs. 1 and 2). The groups of Schatz and co-workers (3) and Neupert (4) have shown that a mitochondrial membrane potential is a key requirement for protein import into mitochondria (5). In normal cells, the mitochondrial membrane potential is mainly maintained by transmembrane proton pumping occurring during electron transfer or during ATP hydrolysis catalyzed by the ATPase-ATP synthase. In °cells depleted of mtDNA, these complexes cannot be functional since all complexes involved in proton pumping contain mtDNA-coded subunits (6). However, proteins of nuclear origin are imported into the °cell mitochondria (7). Therefore, the mitochondrial membrane potential must be maintained by other electrogenic pumps. In yeast, it has been suggested that the adenine nucleotide translocator (ANT) 1 mediates an exchange of ATP 4Ϫ synthesized in the cytosol during glycolysis for ADP 3Ϫ to maintain this mitochondrial membrane potential (8). However, the exact mechanism that maintains this potential has not been thoroughly investigated. Since the mtDNA-coded subunits are essential components for ...

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“…the adenine nucleotide translocase, the peripheral benzodiazepine receptor, and the voltage-dependent anion channel, are all coded by nuclear genes and their production should not be affected by depletion of mtDNA. In contrast, increases in adenine nucleotide translocase 2 and 3 isoforms are detected in 0 cells (43). With the patch-clamp technique, the activity and functional expression level of multiple conductance channels, which appear to be identical to PT pores (44), are found also normal in 0 cells (45).…”

Section: Discussionmentioning

confidence: 99%

Cytochrome c-mediated Apoptosis in Cells Lacking Mitochondrial DNA

Jiang

Cai

Wallace

et al. 1999

Journal of Biological Chemistry

158

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Mitochondria serve as a pivotal component of the apoptotic cell death machinery. However, cells that lack mitochondrial DNA ( 0 cells) retain apparently normal apoptotic signaling. In the present study, we examined mitochondrial mechanisms of apoptosis in 0 osteosarcoma cells treated with staurosporine. Immunohistochemistry revealed that 0 cells maintained a normal cytochrome c distribution in mitochondria even though these cells were deficient in respiration. Upon staurosporine treatment, cytochrome c was released concomitantly with activation of caspase 3 and loss of mitochondrial membrane potential (⌬ m ). After mitochondrial loss of cytochrome c, 0 cells underwent little change in glutathione (GSH) redox potential whereas a dramatic oxidation in GSH/glutathione disulfide (GSSG) pool occurred in parental ؉ cells. These results show that mitochondrial signaling of apoptosis via cytochrome c release was preserved in cells lacking mtDNA. However, intracellular oxidation that normally accompanies apoptosis was lost, indicating that the mitochondrial respiratory chain provides the major source of redox signaling in apoptosis.

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Nuclear responses to depletion of mitochondrial DNA in human cells

Cited by 59 publications

References 17 publications

Large Functional Range of Steady-State Levels of Nuclear and Mitochondrial Transcripts Coding for the Subunits of the Human Mitochondrial OXPHOS System

Large Functional Range of Steady-State Levels of Nuclear and Mitochondrial Transcripts Coding for the Subunits of the Human Mitochondrial OXPHOS System

Functional F1-ATPase Essential in Maintaining Growth and Membrane Potential of Human Mitochondrial DNA-depleted ρ° Cells

Cytochrome c-mediated Apoptosis in Cells Lacking Mitochondrial DNA

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