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Sovilj D, Kelemen CD, Dvorakova S, Zobalova R, Raabova H, Kriska J, Hermanova Z, Knotek T, Anderova M, Klener P, Filimonenko V, Neuzil J, Andera L. Cell-specific modulation of mitochondrial respiration and metabolism by the pro-apoptotic Bcl-2 family members Bax and Bak. Apoptosis 2024; 29:424-438. [PMID: 38001340 DOI: 10.1007/s10495-023-01917-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2023] [Indexed: 11/26/2023]
Abstract
Proteins from the Bcl-2 family play an essential role in the regulation of apoptosis. However, they also possess cell death-unrelated activities that are less well understood. This prompted us to study apoptosis-unrelated activities of the Bax and Bak, pro-apoptotic members of the Bcl-2 family. We prepared Bax/Bak-deficient human cancer cells of different origin and found that while respiration in the glioblastoma U87 Bax/Bak-deficient cells was greatly enhanced, respiration of Bax/Bak-deficient B lymphoma HBL-2 cells was slightly suppressed. Bax/Bak-deficient U87 cells also proliferated faster in culture, formed tumours more rapidly in mice, and showed modulation of metabolism with a considerably increased NAD+/NADH ratio. Follow-up analyses documented increased/decreased expression of mitochondria-encoded subunits of respiratory complexes and stabilization/destabilization of the mitochondrial transcription elongation factor TEFM in Bax/Bak-deficient U87 and HBL-2 cells, respectively. TEFM downregulation using shRNAs attenuated mitochondrial respiration in Bax/Bak-deficient U87 as well as in parental HBL-2 cells. We propose that (post)translational regulation of TEFM levels in Bax/Bak-deficient cells modulates levels of subunits of mitochondrial respiratory complexes that, in turn, contribute to respiration and the accompanying changes in metabolism and proliferation in these cells.
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Affiliation(s)
- Dana Sovilj
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic
| | - Cristina Daniela Kelemen
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic
- Faculty of Science, Charles University, Prague, Czech Republic
| | - Sarka Dvorakova
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic
| | - Renata Zobalova
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic
| | - Helena Raabova
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Jan Kriska
- Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Zuzana Hermanova
- Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Tomas Knotek
- Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Miroslava Anderova
- Institute of Experimental Medicine, Czech Academy of Sciences, Prague, Czech Republic
| | - Pavel Klener
- First Faculty of Medicine, Institute of Pathological Physiology, Charles University, Prague, Czech Republic
| | - Vlada Filimonenko
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic
| | - Jiri Neuzil
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic
- Faculty of Science, Charles University, Prague, Czech Republic
- First Faculty of Medicine, Charles University, Prague, Czech Republic
- School of Pharmacy and Medical Science, Griffith University, Southport, QLD, Australia
| | - Ladislav Andera
- Institute of Biotechnology, Czech Academy of Sciences, Vestec, Prague, Czech Republic.
- Institute of Molecular Genetics, Czech Academy of Sciences, Prague, Czech Republic.
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Grotehans N, McGarry L, Nolte H, Xavier V, Kroker M, Narbona‐Pérez ÁJ, Deshwal S, Giavalisco P, Langer T, MacVicar T. Ribonucleotide synthesis by NME6 fuels mitochondrial gene expression. EMBO J 2023; 42:e113256. [PMID: 37439264 PMCID: PMC10505918 DOI: 10.15252/embj.2022113256] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2022] [Revised: 06/07/2023] [Accepted: 06/19/2023] [Indexed: 07/14/2023] Open
Abstract
Replication of the mitochondrial genome and expression of the genes it encodes both depend on a sufficient supply of nucleotides to mitochondria. Accordingly, dysregulated nucleotide metabolism not only destabilises the mitochondrial genome, but also affects its transcription. Here, we report that a mitochondrial nucleoside diphosphate kinase, NME6, supplies mitochondria with pyrimidine ribonucleotides that are necessary for the transcription of mitochondrial genes. Loss of NME6 function leads to the depletion of mitochondrial transcripts, as well as destabilisation of the electron transport chain and impaired oxidative phosphorylation. These deficiencies are rescued by an exogenous supply of pyrimidine ribonucleosides. Moreover, NME6 is required for the maintenance of mitochondrial DNA when the access to cytosolic pyrimidine deoxyribonucleotides is limited. Our results therefore reveal an important role for ribonucleotide salvage in mitochondrial gene expression.
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Affiliation(s)
- Nils Grotehans
- Max Planck Institute for Biology of AgeingCologneGermany
| | | | - Hendrik Nolte
- Max Planck Institute for Biology of AgeingCologneGermany
| | | | - Moritz Kroker
- Max Planck Institute for Biology of AgeingCologneGermany
| | | | - Soni Deshwal
- Max Planck Institute for Biology of AgeingCologneGermany
| | | | - Thomas Langer
- Max Planck Institute for Biology of AgeingCologneGermany
- Cologne Excellence Cluster on Cellular Stress Responses in Aging‐Associated Diseases (CECAD)University of CologneCologneGermany
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Miranda M, Bonekamp NA, Kühl I. Starting the engine of the powerhouse: mitochondrial transcription and beyond. Biol Chem 2022; 403:779-805. [PMID: 35355496 DOI: 10.1515/hsz-2021-0416] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2021] [Accepted: 03/09/2022] [Indexed: 12/25/2022]
Abstract
Mitochondria are central hubs for cellular metabolism, coordinating a variety of metabolic reactions crucial for human health. Mitochondria provide most of the cellular energy via their oxidative phosphorylation (OXPHOS) system, which requires the coordinated expression of genes encoded by both the nuclear (nDNA) and mitochondrial genomes (mtDNA). Transcription of mtDNA is not only essential for the biogenesis of the OXPHOS system, but also generates RNA primers necessary to initiate mtDNA replication. Like the prokaryotic system, mitochondria have no membrane-based compartmentalization to separate the different steps of mtDNA maintenance and expression and depend entirely on nDNA-encoded factors imported into the organelle. Our understanding of mitochondrial transcription in mammalian cells has largely progressed, but the mechanisms regulating mtDNA gene expression are still poorly understood despite their profound importance for human disease. Here, we review mechanisms of mitochondrial gene expression with a focus on the recent findings in the field of mammalian mtDNA transcription and disease phenotypes caused by defects in proteins involved in this process.
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Affiliation(s)
- Maria Miranda
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, D-50931, Germany
| | - Nina A Bonekamp
- Department of Neuroanatomy, Mannheim Center for Translational Neurosciences (MCTN), Medical Faculty Mannheim, Heidelberg University, Mannheim, D-68167, Germany
| | - Inge Kühl
- Department of Cell Biology, Institute of Integrative Biology of the Cell (I2BC), UMR9198, CEA, CNRS, Université Paris-Saclay, Gif-sur-Yvette, F-91190, France
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