Regulators of mitonuclear balance link mitochondrial metabolism to mtDNA expression
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE224817 | GEO | 2023/08/17
REPOSITORIES: GEO
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Project description:Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells requiring coordinated gene expression across organelles. To identify genes involved in dual-origin protein complex synthesis, we performed FACS-based genome-wide screens analyzing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of Complex IV. We identified novel genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6. We found that PREPL specifically impacts Complex IV biogenesis by acting at the intersection of mitochondrial lipid metabolism and protein synthesis, while NME6, an uncharacterized nucleoside diphosphate kinase (NDPK), controls OXPHOS biogenesis through multiple mechanisms reliant on its NDPK domain. First, NME6 forms a complex with RCC1L, which together perform NDPK activity to maintain local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Second, NME6 modulates the activity of mitoribosome regulatory complexes, altering mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression.
2023-08-17 | GSE240576 | GEO
Project description:Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells requiring coordinated gene expression across organelles. To identify genes involved in dual-origin protein complex synthesis, we performed FACS-based genome-wide screens analyzing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of Complex IV. We identified novel genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6. We found that PREPL specifically impacts Complex IV biogenesis by acting at the intersection of mitochondrial lipid metabolism and protein synthesis, while NME6, an uncharacterized nucleoside diphosphate kinase (NDPK), controls OXPHOS biogenesis through multiple mechanisms reliant on its NDPK domain. First, NME6 forms a complex with RCC1L, which together perform NDPK activity to maintain local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Second, NME6 modulates the activity of mitoribosome regulatory complexes, altering mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression.
2023-08-17 | GSE224818 | GEO
Project description:Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells requiring coordinated gene expression across organelles. To identify genes involved in dual-origin protein complex synthesis, we performed fluorescence-activated cell-sorting-based genome-wide screens analysing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of Complex IV. We identified genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6. We found that PREPL specifically impacts Complex IV biogenesis by acting at the intersection of mitochondrial lipid metabolism and protein synthesis, whereas NME6, an uncharacterized nucleoside diphosphate kinase, controls OXPHOS biogenesis through multiple mechanisms reliant on its NDPK domain. Firstly, NME6 forms a complex with RCC1L, which together perform nucleoside diphosphate kinase activity to maintain local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Secondly, NME6 modulates the activity of mitoribosome regulatory complexes, altering mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression.
2023-08-17 | GSE224503 | GEO
Project description:Mitochondrial oxidative phosphorylation (OXPHOS) complexes are assembled from proteins encoded by both nuclear and mitochondrial DNA. These dual-origin enzymes pose a complex gene regulatory challenge for cells requiring coordinated gene expression across organelles. To identify genes involved in dual-origin protein complex synthesis, we performed FACS-based genome-wide screens analyzing mutant cells with unbalanced levels of mitochondrial- and nuclear-encoded subunits of Complex IV. We identified novel genes involved in OXPHOS biogenesis, including two uncharacterized genes: PREPL and NME6. We found that PREPL specifically impacts Complex IV biogenesis by acting at the intersection of mitochondrial lipid metabolism and protein synthesis, while NME6, an uncharacterized nucleoside diphosphate kinase (NDPK), controls OXPHOS biogenesis through multiple mechanisms reliant on its NDPK domain. First, NME6 forms a complex with RCC1L, which together perform NDPK activity to maintain local mitochondrial pyrimidine triphosphate levels essential for mitochondrial RNA abundance. Second, NME6 modulates the activity of mitoribosome regulatory complexes, altering mitoribosome assembly and mitochondrial RNA pseudouridylation. Taken together, we propose that NME6 acts as a link between compartmentalized mitochondrial metabolites and mitochondrial gene expression.
2023-08-23 | PXD044812 | Pride
Project description:Background: Transcription control of mitochondrial metabolism is essential for cellular function. A better understanding of this process will aid the elucidation of mitochondrial disorders, in particular of the many genetically unsolved cases of oxidative phosphorylation (OXPHOS) deficiency. Yet, to date only few studies have investigated nuclear gene regulation in the context of OXPHOS deficiency. In this study, we combined RNA sequencing of human complex I-deficient patient cells across 32 conditions of perturbed mitochondrial metabolism, with a comprehensive analysis of gene expression patterns, co-expression calculations and transcription factor binding sites. Results: Our analysis shows that OXPHOS genes have a significantly higher co-expression with each other than with other genes, including mitochondrial genes. We found no evidence for complex-specific mRNA expression regulation in the tested cell types and conditions: subunits of different OXPHOS complexes are similarly (co-)expressed and regulated by a common set of transcription factors. However, we did observe significant differences between the expression of OXPHOS complex subunits compared to assembly factors, suggesting divergent transcription programs. Furthermore, complex I co-expression calculations identified 684 genes with a likely role in OXPHOS biogenesis and function. Analysis of evolutionarily conserved transcription factor binding sites in the promoters of these genes revealed almost all known OXPHOS regulators (including GABP, NRF1/2, SP1, YY1, E-box factors) and a set of six yet uncharacterized candidate transcription factors (ELK1, KLF7, SP4, EHF, ZNF143, and EL2). Conclusions: OXPHOS genes share an expression program distinct from other mitochondrial genes, indicative of targeted regulation of this mitochondrial sub-process. Within the subset of OXPHOS genes we established a difference in expression between subunits and assembly factors. Most transcription regulators of genes that co-express with complex I are well-established factors for OXPHOS biogenesis. For the remaining six factors we here suggest for the first time a link with transcription regulation in OXPHOS deficiency. RNA-SEQ of whole cell RNA in 2 control and 2 complex I deficient patient fibroblast cell lines treated with 4 compounds in duplicate, resulting in a total of 2x2x4x2=32 samples
2015-08-31 | E-GEOD-65634 | biostudies-arrayexpress
Project description:Oxidative phosphorylation (OXPHOS) is essential for the synthesis of the vast majority of ATP in eukaryotic cells. It is carried out by multi-protein assemblies that form the electron transport chain (ETC), which are coupled to the mitochondrial ATP synthase, which uses the proton gradient generated by the ETC to drive ATP synthesis. The assembly of the OXPHOS protein machinery requires the coordinated integration of proteins encoded in the nuclear and the mitochondrial genomes, imposing an additional layer of complexity. While the biogenesis of the individual OXPHOS complexes is well understood, it remains unknown how the assembly of the ETC and ATP synthase is coordinated to achieve the correct stoichiometry of the OXPHOS machinery. Here, we identify the mitochondrial regulatory hub for respiratory assembly (MiRA), which serves as a platform on which complex IV and complex V biogenesis are synchronised to ensure balanced assembly of the ETC and complex V. At the molecular level, this is achieved by a stop-and-go safeguarding mechanism: The novel mitochondrial protein Mra1 binds to and slows down complex IV assembly. Two Go signals are then required for assembly to proceed: Binding of the complex IV assembly factor Rcf2 and interaction with the mitoribosome, which translates the complex V subunit Atp9. Both Go signals induce the clipping and subsequent degradation of Mra1, relieving the molecular brake and allowing parallel maturation of complexes IV and V. The absence of the stop-and-go safety mechanism results in the formation of immature complexes, decreased ATP levels and reduced cell viability. The antagonistic activities at MiRA provide a regulated orchestration of complex IV and V assembly which is essential to avoid the predominance of either complex and an unbalanced ratio of OXPHOS complexes, thus ensuring the correct stoichiometry of protein machineries encoded by two different genomes.
2024-02-16 | PXD044749 | Pride
Project description:Oxidative phosphorylation (OXPHOS) is essential for the synthesis of the vast majority of ATP in eukaryotic cells. It is carried out by multi-protein assemblies that form the electron transport chain (ETC), which are coupled to the mitochondrial ATP synthase, which uses the proton gradient generated by the ETC to drive ATP synthesis. The assembly of the OXPHOS protein machinery requires the coordinated integration of proteins encoded in the nuclear and the mitochondrial genomes, imposing an additional layer of complexity. While the biogenesis of the individual OXPHOS complexes is well understood, it remains unknown how the assembly of the ETC and ATP synthase is coordinated to achieve the correct stoichiometry of the OXPHOS machinery. Here, we identify the mitochondrial regulatory hub for respiratory assembly (MiRA), which serves as a platform on which complex IV and complex V biogenesis are synchronised to ensure balanced assembly of the ETC and complex V. At the molecular level, this is achieved by a stop-and-go safeguarding mechanism: The novel mitochondrial protein Mra1 binds to and slows down complex IV assembly. Two Go signals are then required for assembly to proceed: Binding of the complex IV assembly factor Rcf2 and interaction with the mitoribosome, which translates the complex V subunit Atp9. Both Go signals induce the clipping and subsequent degradation of Mra1, relieving the molecular brake and allowing parallel maturation of complexes IV and V. The absence of the stop-and-go safety mechanism results in the formation of immature complexes, decreased ATP levels and reduced cell viability. The antagonistic activities at MiRA provide a regulated orchestration of complex IV and V assembly which is essential to avoid the predominance of either complex and an unbalanced ratio of OXPHOS complexes, thus ensuring the correct stoichiometry of protein machineries encoded by two different genomes.
2024-02-16 | PXD044615 | Pride
Project description:Oxidative phosphorylation (OXPHOS) is essential for the synthesis of the vast majority of ATP in eukaryotic cells. It is carried out by multi-protein assemblies that form the electron transport chain (ETC), which are coupled to the mitochondrial ATP synthase, which uses the proton gradient generated by the ETC to drive ATP synthesis. The assembly of the OXPHOS protein machinery requires the coordinated integration of proteins encoded in the nuclear and the mitochondrial genomes, imposing an additional layer of complexity. While the biogenesis of the individual OXPHOS complexes is well understood, it remains unknown how the assembly of the ETC and ATP synthase is coordinated to achieve the correct stoichiometry of the OXPHOS machinery. Here, we identify the mitochondrial regulatory hub for respiratory assembly (MiRA), which serves as a platform on which complex IV and complex V biogenesis are synchronised to ensure balanced assembly of the ETC and complex V. At the molecular level, this is achieved by a stop-and-go safeguarding mechanism: The novel mitochondrial protein Mra1 binds to and slows down complex IV assembly. Two Go signals are then required for assembly to proceed: Binding of the complex IV assembly factor Rcf2 and interaction with the mitoribosome, which translates the complex V subunit Atp9. Both Go signals induce the clipping and subsequent degradation of Mra1, relieving the molecular break and allowing parallel maturation of complexes IV and V. The absence of the stop-and-go safety mechanism results in the formation of immature complexes, decreased ATP levels and reduced cell viability. The antagonistic activities at MiRA provide a regulated orchestration of complex IV and V assembly which is essential to avoid the predominance of either complex and an unbalanced ratio of OXPHOS complexes, thus ensuring the correct stoichiometry of protein machineries encoded by two different genomes.
2024-02-16 | PXD044800 | Pride
Project description:Background: Transcription control of mitochondrial metabolism is essential for cellular function. A better understanding of this process will aid the elucidation of mitochondrial disorders, in particular of the many genetically unsolved cases of oxidative phosphorylation (OXPHOS) deficiency. Yet, to date only few studies have investigated nuclear gene regulation in the context of OXPHOS deficiency. In this study, we combined RNA sequencing of human complex I-deficient patient cells across 32 conditions of perturbed mitochondrial metabolism, with a comprehensive analysis of gene expression patterns, co-expression calculations and transcription factor binding sites. Results: Our analysis shows that OXPHOS genes have a significantly higher co-expression with each other than with other genes, including mitochondrial genes. We found no evidence for complex-specific mRNA expression regulation in the tested cell types and conditions: subunits of different OXPHOS complexes are similarly (co-)expressed and regulated by a common set of transcription factors. However, we did observe significant differences between the expression of OXPHOS complex subunits compared to assembly factors, suggesting divergent transcription programs. Furthermore, complex I co-expression calculations identified 684 genes with a likely role in OXPHOS biogenesis and function. Analysis of evolutionarily conserved transcription factor binding sites in the promoters of these genes revealed almost all known OXPHOS regulators (including GABP, NRF1/2, SP1, YY1, E-box factors) and a set of six yet uncharacterized candidate transcription factors (ELK1, KLF7, SP4, EHF, ZNF143, and EL2). Conclusions: OXPHOS genes share an expression program distinct from other mitochondrial genes, indicative of targeted regulation of this mitochondrial sub-process. Within the subset of OXPHOS genes we established a difference in expression between subunits and assembly factors. Most transcription regulators of genes that co-express with complex I are well-established factors for OXPHOS biogenesis. For the remaining six factors we here suggest for the first time a link with transcription regulation in OXPHOS deficiency.
2015-08-31 | GSE65634 | GEO
Project description:Oxidative phosphorylation (OXPHOS) complexes, encoded by both mitochondrial and nuclear DNA, are essential producers of cellular ATP, but how nuclear and mitochondrial gene expression steps are coordinated to achieve balanced OXPHOS subunit biogenesis remains unresolved. Here, we present a parallel quantitative analysis of the human nuclear and mitochondrial messenger RNA (mt-mRNA) life cycles, including transcript production, processing, ribosome association, and degradation. The kinetic rates of nearly every stage of gene expression differed starkly across compartments. Compared to nuclear mRNAs, mt-mRNAs were produced 1100-fold higher, degraded 7-fold faster, and accumulated to 160-fold higher levels. Quantitative modeling and depletion of mitochondrial factors, LRPPRC and FASTKD5, identified critical points of mitochondrial regulatory control, revealing that the mitonuclear expression disparities intrinsically arise from the highly polycistronic nature of human mitochondrial pre-mRNA. We propose that resolving these differences requires a 100-fold slower mitochondrial translation rate, illuminating the mitoribosome as a nexus of mitonuclear co-regulation.
2024-03-18 | GSE224163 | GEO