51
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Organization and expression of the mammalian mitochondrial genome. Nat Rev Genet 2022; 23:606-623. [PMID: 35459860 DOI: 10.1038/s41576-022-00480-x] [Citation(s) in RCA: 47] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/21/2022] [Indexed: 02/07/2023]
Abstract
The mitochondrial genome encodes core subunits of the respiratory chain that drives oxidative phosphorylation and is, therefore, essential for energy conversion. Advances in high-throughput sequencing technologies and cryoelectron microscopy have shed light on the structure and organization of the mitochondrial genome and revealed unique mechanisms of mitochondrial gene regulation. New animal models of impaired mitochondrial protein synthesis have shown how the coordinated regulation of the cytoplasmic and mitochondrial translation machineries ensures the correct assembly of the respiratory chain complexes. These new technologies and disease models are providing a deeper understanding of mitochondrial genome organization and expression and of the diseases caused by impaired energy conversion, including mitochondrial, neurodegenerative, cardiovascular and metabolic diseases. They also provide avenues for the development of treatments for these conditions.
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52
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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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53
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Phosphorylation and acetylation of mitochondrial transcription factor A promote transcription processivity without compromising initiation or DNA compaction. J Biol Chem 2022; 298:101815. [PMID: 35278431 PMCID: PMC9006650 DOI: 10.1016/j.jbc.2022.101815] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2021] [Revised: 02/27/2022] [Accepted: 02/28/2022] [Indexed: 11/15/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM) plays important roles in mitochondrial DNA compaction, transcription initiation, and in the regulation of processes like transcription and replication processivity. It is possible that TFAM is locally regulated within the mitochondrial matrix via such mechanisms as phosphorylation by protein kinase A and nonenzymatic acetylation by acetyl-CoA. Here, we demonstrate that DNA-bound TFAM is less susceptible to these modifications. We confirmed using EMSAs that phosphorylated or acetylated TFAM compacted circular double-stranded DNA just as well as unmodified TFAM and provide an in-depth analysis of acetylated sites on TFAM. We show that both modifications of TFAM increase the processivity of mitochondrial RNA polymerase during transcription through TFAM-imposed barriers on DNA, but that TFAM bearing either modification retains its full activity in transcription initiation. We conclude that TFAM phosphorylation by protein kinase A and nonenzymatic acetylation by acetyl-CoA are unlikely to occur at the mitochondrial DNA and that modified free TFAM retains its vital functionalities like compaction and transcription initiation while enhancing transcription processivity.
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54
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Proteomic analysis of the mitochondrial glucocorticoid receptor interacting proteins reveals pyruvate dehydrogenase and mitochondrial 60 kDa heat shock protein as potent binding partners. J Proteomics 2022; 257:104509. [DOI: 10.1016/j.jprot.2022.104509] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2021] [Revised: 01/26/2022] [Accepted: 01/27/2022] [Indexed: 11/20/2022]
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55
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Singh M, Posse V, Peter B, Falkenberg M, Gustafsson C. Ribonucleotides embedded in template DNA impair mitochondrial RNA polymerase progression. Nucleic Acids Res 2022; 50:989-999. [PMID: 35018464 PMCID: PMC8789056 DOI: 10.1093/nar/gkab1251] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Revised: 11/30/2021] [Accepted: 12/07/2021] [Indexed: 11/12/2022] Open
Abstract
Human mitochondria lack ribonucleotide excision repair pathways, causing misincorporated ribonucleotides (rNMPs) to remain embedded in the mitochondrial genome. Previous studies have demonstrated that human mitochondrial DNA polymerase γ can bypass a single rNMP, but that longer stretches of rNMPs present an obstacle to mitochondrial DNA replication. Whether embedded rNMPs also affect mitochondrial transcription has not been addressed. Here we demonstrate that mitochondrial RNA polymerase elongation activity is affected by a single, embedded rNMP in the template strand. The effect is aggravated at stretches with two or more consecutive rNMPs in a row and cannot be overcome by addition of the mitochondrial transcription elongation factor TEFM. Our findings lead us to suggest that impaired transcription may be of functional relevance in genetic disorders associated with imbalanced nucleotide pools and higher levels of embedded rNMPs.
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Affiliation(s)
- Meenakshi Singh
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Viktor Posse
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, Institute of Biomedicine, University of Gothenburg, Gothenburg, SE-405 30, Sweden
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56
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Yu HJ, Xiao GL, Zhao YY, Wang XX, Lan R. Targeting Mitochondrial Metabolism and RNA Polymerase POLRMT to Overcome Multidrug Resistance in Cancer. Front Chem 2022; 9:775226. [PMID: 34976949 PMCID: PMC8716502 DOI: 10.3389/fchem.2021.775226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 12/06/2021] [Indexed: 11/13/2022] Open
Abstract
Clinically, the prognosis of tumor therapy is fundamentally affected by multidrug resistance (MDR), which is primarily a result of enhanced drug efflux mediated by channels in the membrane that reduce drug accumulation in tumor cells. How to restore the sensitivity of tumor cells to chemotherapy is an ongoing and pressing clinical issue. There is a prevailing view that tumor cells turn to glycolysis for energy supply due to hypoxia. However, studies have shown that mitochondria also play crucial roles, such as providing intermediates for biosynthesis through the tricarboxylic acid (TCA) cycle and a plenty of ATP to fuel cells through the complete breakdown of organic matter by oxidative phosphorylation (OXPHOS). High OXPHOS have been found in some tumors, particularly in cancer stem cells (CSCs), which possess increased mitochondria mass and may be depends on OXPHOS for energy supply. Therefore, they are sensitive to inhibitors of mitochondrial metabolism. In view of this, we should consider mitochondrial metabolism when developing drugs to overcome MDR, where mitochondrial RNA polymerase (POLRMT) would be the focus, as it is responsible for mitochondrial gene expression. Inhibition of POLRMT could disrupt mitochondrial metabolism at its source, causing an energy crisis and ultimately eradicating tumor cells. In addition, it may restore the energy supply of MDR cells to glycolysis and re-sensitize them to conventional chemotherapy. Furthermore, we discuss the rationale and strategies for designing new therapeutic molecules for MDR cancers by targeting POLRMT.
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Affiliation(s)
- Hui-Jing Yu
- School of Pharmaceutical Sciences, Shenzhen University Health Science Center, Shenzhen, China
| | - Guan-Li Xiao
- School of Pharmaceutical Sciences, Shenzhen University Health Science Center, Shenzhen, China
| | - Yu-Ying Zhao
- Department of Cell Biology and Medical Genetics, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, China
| | - Xin-Xin Wang
- Department of Cell Biology and Medical Genetics, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, China
| | - Rongfeng Lan
- Department of Cell Biology and Medical Genetics, School of Basic Medical Sciences, Shenzhen University Health Science Center, Shenzhen, China
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57
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Zamudio-Ochoa A, Morozov YI, Sarfallah A, Anikin M, Temiakov D. OUP accepted manuscript. Nucleic Acids Res 2022; 50:2765-2781. [PMID: 35191499 PMCID: PMC8934621 DOI: 10.1093/nar/gkac103] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2021] [Revised: 01/27/2022] [Accepted: 02/03/2022] [Indexed: 11/13/2022] Open
Abstract
Recognition of mammalian mitochondrial promoters requires the concerted action of mitochondrial RNA polymerase (mtRNAP) and transcription initiation factors TFAM and TFB2M. In this work, we found that transcript slippage results in heterogeneity of the human mitochondrial transcripts in vivo and in vitro. This allowed us to correctly interpret the RNAseq data, identify the bona fide transcription start sites (TSS), and assign mitochondrial promoters for > 50% of mammalian species and some other vertebrates. The divergent structure of the mammalian promoters reveals previously unappreciated aspects of mtDNA evolution. The correct assignment of TSS also enabled us to establish the precise register of the DNA in the initiation complex and permitted investigation of the sequence-specific protein-DNA interactions. We determined the molecular basis of promoter recognition by mtRNAP and TFB2M, which cooperatively recognize bases near TSS in a species-specific manner. Our findings reveal a role of mitochondrial transcription machinery in mitonuclear coevolution and speciation.
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Affiliation(s)
- Angelica Zamudio-Ochoa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Yaroslav I Morozov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, 1020 Locust Street, Philadelphia, PA 19107, USA
| | - Michael Anikin
- Department of Cell Biology and Neuroscience, Rowan University, School of Osteopathic Medicine, 42 E Laurel Rd, Stratford, NJ 08084, USA
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58
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Choi WS, Garcia-Diaz M. A minimal motif for sequence recognition by mitochondrial transcription factor A (TFAM). Nucleic Acids Res 2021; 50:322-332. [PMID: 34928349 PMCID: PMC8754647 DOI: 10.1093/nar/gkab1230] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2021] [Revised: 11/13/2021] [Accepted: 12/10/2021] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM) plays a critical role in mitochondrial transcription initiation and mitochondrial DNA (mtDNA) packaging. Both functions require DNA binding, but in one case TFAM must recognize a specific promoter sequence, while packaging requires coating of mtDNA by association with non sequence-specific regions. The mechanisms by which TFAM achieves both sequence-specific and non sequence-specific recognition have not yet been determined. Existing crystal structures of TFAM bound to DNA allowed us to identify two guanine-specific interactions that are established between TFAM and the bound DNA. These interactions are observed when TFAM is bound to both specific promoter sequences and non-sequence specific DNA. These interactions are established with two guanine bases separated by 10 random nucleotides (GN10G). Our biochemical results demonstrate that the GN10G consensus is essential for transcriptional initiation and contributes to facilitating TFAM binding to DNA substrates. Furthermore, we report a crystal structure of TFAM in complex with a non sequence-specific sequence containing a GN10G consensus. The structure reveals a unique arrangement in which TFAM bridges two DNA substrates while maintaining the GN10G interactions. We propose that the GN10G consensus is key to facilitate the interaction of TFAM with DNA.
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Affiliation(s)
- Woo Suk Choi
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
| | - Miguel Garcia-Diaz
- Department of Pharmacological Sciences, Stony Brook University, Stony Brook, NY 11794, USA
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59
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An in vitro system to silence mitochondrial gene expression. Cell 2021; 184:5824-5837.e15. [PMID: 34672953 DOI: 10.1016/j.cell.2021.09.033] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 09/10/2021] [Accepted: 09/24/2021] [Indexed: 11/21/2022]
Abstract
The human mitochondrial genome encodes thirteen core subunits of the oxidative phosphorylation system, and defects in mitochondrial gene expression lead to severe neuromuscular disorders. However, the mechanisms of mitochondrial gene expression remain poorly understood due to a lack of experimental approaches to analyze these processes. Here, we present an in vitro system to silence translation in purified mitochondria. In vitro import of chemically synthesized precursor-morpholino hybrids allows us to target translation of individual mitochondrial mRNAs. By applying this approach, we conclude that the bicistronic, overlapping ATP8/ATP6 transcript is translated through a single ribosome/mRNA engagement. We show that recruitment of COX1 assembly factors to translating ribosomes depends on nascent chain formation. By defining mRNA-specific interactomes for COX1 and COX2, we reveal an unexpected function of the cytosolic oncofetal IGF2BP1, an RNA-binding protein, in mitochondrial translation. Our data provide insight into mitochondrial translation and innovative strategies to investigate mitochondrial gene expression.
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60
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Inatomi T, Matsuda S, Ishiuchi T, Do Y, Nakayama M, Abe S, Kasho K, Wanrooij S, Nakada K, Ichiyanagi K, Sasaki H, Yasukawa T, Kang D. TFB2M and POLRMT are essential for mammalian mitochondrial DNA replication. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2021; 1869:119167. [PMID: 34744028 DOI: 10.1016/j.bbamcr.2021.119167] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Revised: 10/13/2021] [Accepted: 10/13/2021] [Indexed: 12/24/2022]
Abstract
Two classes of replication intermediates have been observed from mitochondrial DNA (mtDNA) in many mammalian tissue and cells with two-dimensional agarose gel electrophoresis. One is assigned to leading-strand synthesis in the absence of synchronous lagging-strand synthesis (strand-asynchronous replication), and the other has properties of coupled leading- and lagging-strand synthesis (strand-coupled replication). While strand-asynchronous replication is primed by long noncoding RNA synthesized from a defined transcription initiation site, little is known about the commencement of strand-coupled replication. To investigate it, we attempted to abolish strand-asynchronous replication in cultured human cybrid cells by knocking out the components of the transcription initiation complexes, mitochondrial transcription factor B2 (TFB2M/mtTFB2) and mitochondrial RNA polymerase (POLRMT/mtRNAP). Unexpectedly, removal of either protein resulted in complete mtDNA loss, demonstrating for the first time that TFB2M and POLRMT are indispensable for the maintenance of human mtDNA. Moreover, a lack of TFB2M could not be compensated for by mitochondrial transcription factor B1 (TFB1M/mtTFB1). These findings indicate that TFB2M and POLRMT are crucial for the priming of not only strand-asynchronous but also strand-coupled replication, providing deeper insights into the molecular basis of mtDNA replication initiation.
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Affiliation(s)
- Teppei Inatomi
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Shigeru Matsuda
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan; Department of Modomics Biology and Medicine, Institute of Development, Aging and Cancer, Tohoku University, 4-1 Seiryocho, Aoba-ku, Sendai-shi, Miyagi 980-8575, Japan
| | - Takashi Ishiuchi
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Yura Do
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Masunari Nakayama
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Shusaku Abe
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Kazutoshi Kasho
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Sjoerd Wanrooij
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå, Sweden
| | - Kazuto Nakada
- Faculty of Life and Environmental Sciences, University of Tsukuba, 1-1-1 Tennoudai, Tsukuba-shi, Ibaraki 305-8572, Japan
| | - Kenji Ichiyanagi
- Department of Animal Sciences, Graduate School of Bioagricultural Sciences, Nagoya University, Furo-cho, Chikusa-ku, Nagoya-shi, Aichi 464-8601, Japan
| | - Hiroyuki Sasaki
- Division of Epigenomics and Development, Medical Institute of Bioregulation, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
| | - Takehiro Yasukawa
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan; Department of Pathology and Oncology, Juntendo University School of Medicine, 2-1-1 Hongo, Bunkyo-ku, Tokyo 113-8421, Japan.
| | - Dongchon Kang
- Department of Clinical Chemistry and Laboratory Medicine, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka-shi, Fukuoka 812-8582, Japan
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61
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Phase separation drives the self-assembly of mitochondrial nucleoids for transcriptional modulation. Nat Struct Mol Biol 2021; 28:900-908. [PMID: 34711968 DOI: 10.1038/s41594-021-00671-w] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Accepted: 09/14/2021] [Indexed: 11/08/2022]
Abstract
Mitochondria, the only semiautonomous organelles in mammalian cells, possess a circular, double-stranded genome termed mitochondrial DNA (mtDNA). While nuclear genomic DNA compaction, chromatin compartmentalization and transcription are known to be regulated by phase separation, how the mitochondrial nucleoid, a highly compacted spherical suborganelle, is assembled and functions is unknown. Here we assembled mitochondrial nucleoids in vitro and show that mitochondrial transcription factor A (TFAM) undergoes phase separation with mtDNA to drive nucleoid self-assembly. Moreover, nucleoid droplet formation promotes recruitment of the transcription machinery via a special, co-phase separation that concentrates transcription initiation, elongation and termination factors, and retains substrates to facilitate mtDNA transcription. We propose a model of mitochondrial nucleoid self-assembly driven by phase separation, and a pattern of co-phase separation involved in mitochondrial transcriptional regulation, which orchestrates the roles of TFAM in both mitochondrial nucleoid organization and transcription.
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62
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Zhang T, Ding S, Wang R. Research Progress of Mitochondrial Mechanism in NLRP3 Inflammasome Activation and Exercise Regulation of NLRP3 Inflammasome. Int J Mol Sci 2021; 22:ijms221910866. [PMID: 34639204 PMCID: PMC8509472 DOI: 10.3390/ijms221910866] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Revised: 09/29/2021] [Accepted: 09/30/2021] [Indexed: 12/13/2022] Open
Abstract
NLRP3 is an important pattern recognition receptor in the innate immune system, and its activation induces a large number of pro-inflammatory cytokines, IL-1β and IL-18 which are involved in the development of various diseases. In recent years, it has been suggested that mitochondria are the platform for NLRP3 inflammasome activation. Additionally, exercise is considered as an important intervention strategy to mediate the innate immune responses. Generally, chronic moderate-intensity endurance training, resistance training and high-intensity interval training inhibit NLRP3 inflammasome activation in response to various pathological factors. In contrast, acute exercise activates NLRP3 inflammasome. However, the mechanisms by which exercise regulates NLRP3 inflammasome activation are largely unclear. Therefore, the mechanism of NLRP3 inflammasome activation is discussed mainly from the perspective of mitochondria in this review. Moreover, the effect and potential mechanism of exercise on NLRP3 inflammasome are explored, hoping to provide new target for relevant research.
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Affiliation(s)
- Tan Zhang
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China;
- Shanghai Frontiers Science Research Base of Exercise and Metabolic Health, Shanghai 200438, China
| | - Shuzhe Ding
- Key Laboratory of Adolescent Health Assessment and Exercise Intervention, Ministry of Education, East China Normal University, Shanghai 200241, China
- Correspondence: (S.D.); (R.W.)
| | - Ru Wang
- School of Kinesiology, Shanghai University of Sport, Shanghai 200438, China;
- Shanghai Frontiers Science Research Base of Exercise and Metabolic Health, Shanghai 200438, China
- Correspondence: (S.D.); (R.W.)
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63
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Hirayama T. PARN-like Proteins Regulate Gene Expression in Land Plant Mitochondria by Modulating mRNA Polyadenylation. Int J Mol Sci 2021; 22:ijms221910776. [PMID: 34639116 PMCID: PMC8509313 DOI: 10.3390/ijms221910776] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 09/21/2021] [Accepted: 10/02/2021] [Indexed: 11/20/2022] Open
Abstract
Mitochondria have their own double-stranded DNA genomes and systems to regulate transcription, mRNA processing, and translation. These systems differ from those operating in the host cell, and among eukaryotes. In recent decades, studies have revealed several plant-specific features of mitochondrial gene regulation. The polyadenylation status of mRNA is critical for its stability and translation in mitochondria. In this short review, I focus on recent advances in understanding the mechanisms regulating mRNA polyadenylation in plant mitochondria, including the role of poly(A)-specific ribonuclease-like proteins (PARNs). Accumulating evidence suggests that plant mitochondria have unique regulatory systems for mRNA poly(A) status and that PARNs play pivotal roles in these systems.
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Affiliation(s)
- Takashi Hirayama
- Institute of Plant Science and Resources, Okayama University, 2-20-1 Chuo, Kurahiki 710-0046, Okayama, Japan
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64
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Chang H, Li J, Luo Y, Wu B, Yuan C, Geng X. TFB2M activates aerobic glycolysis in hepatocellular carcinoma cells through the NAD + /SIRT3/HIF-1α signaling. J Gastroenterol Hepatol 2021; 36:2978-2988. [PMID: 33982328 DOI: 10.1111/jgh.15548] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 04/25/2021] [Accepted: 05/11/2021] [Indexed: 12/13/2022]
Abstract
BACKGROUND AND AIM Increased aerobic glycolysis has been well-known as a hallmark of cancer, which is closely related to mitochondrial dysfunction. TFB2M (mitochondrial transcription factor B2) is a core mitochondrial transcription factor, which has been shown by us to play an oncogenic role in hepatocellular carcinoma (HCC). However, whether TFB2M contributes to the aerobic glycolysis in HCC cells remains unexplored. METHODS The role and underlying molecular mechanisms of TFB2M in the regulation of aerobic glycolysis in HCC cells were systematically investigated by in vitro cell glucose metabolism and metabolomics analyses. Besides, the effects of TFB2M-regulated aerobic glycolysis in the growth and metastasis of HCC cells were also explored. RESULTS Here, we show that TFB2M markedly enhanced the reprogramming of glucose metabolism from oxidative phosphorylation to aerobic glycolysis mainly through two mechanisms. On the one hand, TFB2M increased the expressions of glycolytic genes GAPDH, LDHA, GLUT1, and HK2. On the other hand, TFB2M decreased the expression of peroxisome proliferator-activated receptor gamma coactivator 1 alpha (PGC-1α), a critical regulator of mitochondrial respiration. Mechanistically, TFB2M regulates the upregulation of glycolytic genes and downregulation of PGC-1α mainly through NAD+ /SIRT3/HIF-1α signaling. Additionally, we found that TFBM2 promoted the progression of HCC cells through HIF-1α-regulated reprogramming of glucose metabolism. CONCLUSIONS Our findings indicate that TFB2M serves as a critical glucose metabolic reprogramming mechanism in tumorigenesis, which could be used as potential therapeutic target in HCC.
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Affiliation(s)
- Hulin Chang
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
| | - Jibin Li
- State Key Laboratory of Cancer Biology and Experimental Teaching Center of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Ying Luo
- Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Bing Wu
- Department of Geriatrics, The 940th Hospital of Joint Logistics Support Force of Chinese People's Liberation Army, Lanzhou, China
| | - Chong Yuan
- Department of Clinical Laboratory, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Xilin Geng
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
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65
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Sarfallah A, Zamudio-Ochoa A, Anikin M, Temiakov D. Mechanism of transcription initiation and primer generation at the mitochondrial replication origin OriL. EMBO J 2021; 40:e107988. [PMID: 34423452 DOI: 10.15252/embj.2021107988] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 07/19/2021] [Accepted: 07/27/2021] [Indexed: 11/09/2022] Open
Abstract
The intricate process of human mtDNA replication requires the coordinated action of both transcription and replication machineries. Transcription and replication events at the lagging strand of mtDNA prompt the formation of a stem-loop structure (OriL) and the synthesis of a ∼25 nt RNA primer by mitochondrial RNA polymerase (mtRNAP). The mechanisms by which mtRNAP recognizes OriL, initiates transcription, and transfers the primer to the replisome are poorly understood. We found that transcription initiation at OriL involves slippage of the nascent transcript. The transcript slippage is essential for initiation complex stability and its ability to translocate the mitochondrial DNA polymerase gamma, PolG, which pre-binds to OriL, downstream of the replication origin thus allowing for the primer synthesis. Our data suggest the primosome assembly at OriL-a complex of mtRNAP and PolG-can efficiently generate the primer, transfer it to the replisome, and protect it from degradation by mitochondrial endonucleases.
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Affiliation(s)
- Azadeh Sarfallah
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Angelica Zamudio-Ochoa
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
| | - Michael Anikin
- Department of Cell Biology and Neuroscience, School of Osteopathic Medicine, Rowan University, Stratford, NJ, USA
| | - Dmitry Temiakov
- Department of Biochemistry and Molecular Biology, Thomas Jefferson University, Philadelphia, PA, USA
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Bhatta A, Dienemann C, Cramer P, Hillen HS. Structural basis of RNA processing by human mitochondrial RNase P. Nat Struct Mol Biol 2021; 28:713-723. [PMID: 34489609 PMCID: PMC8437803 DOI: 10.1038/s41594-021-00637-y] [Citation(s) in RCA: 48] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2021] [Accepted: 07/01/2021] [Indexed: 02/07/2023]
Abstract
Human mitochondrial transcripts contain messenger and ribosomal RNAs flanked by transfer RNAs (tRNAs), which are excised by mitochondrial RNase (mtRNase) P and Z to liberate all RNA species. In contrast to nuclear or bacterial RNase P, mtRNase P is not a ribozyme but comprises three protein subunits that carry out RNA cleavage and methylation by unknown mechanisms. Here, we present the cryo-EM structure of human mtRNase P bound to precursor tRNA, which reveals a unique mechanism of substrate recognition and processing. Subunits TRMT10C and SDR5C1 form a subcomplex that binds conserved mitochondrial tRNA elements, including the anticodon loop, and positions the tRNA for methylation. The endonuclease PRORP is recruited and activated through interactions with its PPR and nuclease domains to ensure precise pre-tRNA cleavage. The structure provides the molecular basis for the first step of RNA processing in human mitochondria.
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Affiliation(s)
- Arjun Bhatta
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany
- Research Group Structure and Function of Molecular Machines, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Christian Dienemann
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
- Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), University of Göttingen, Göttingen, Germany
| | - Hauke S Hillen
- Department of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
- Research Group Structure and Function of Molecular Machines, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
- Cluster of Excellence 'Multiscale Bioimaging: from Molecular Machines to Networks of Excitable Cells' (MBExC), University of Göttingen, Göttingen, Germany.
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67
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Bonekamp NA, Jiang M, Motori E, Garcia Villegas R, Koolmeister C, Atanassov I, Mesaros A, Park CB, Larsson NG. High levels of TFAM repress mammalian mitochondrial DNA transcription in vivo. Life Sci Alliance 2021; 4:4/11/e202101034. [PMID: 34462320 PMCID: PMC8408345 DOI: 10.26508/lsa.202101034] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2021] [Revised: 08/10/2021] [Accepted: 08/20/2021] [Indexed: 01/04/2023] Open
Abstract
Mitochondrial transcription factor A (TFAM) is compacting mitochondrial DNA (dmtDNA) into nucleoids and directly controls mtDNA copy number. Here, we show that the TFAM-to-mtDNA ratio is critical for maintaining normal mtDNA expression in different mouse tissues. Moderately increased TFAM protein levels increase mtDNA copy number but a normal TFAM-to-mtDNA ratio is maintained resulting in unaltered mtDNA expression and normal whole animal metabolism. Mice ubiquitously expressing very high TFAM levels develop pathology leading to deficient oxidative phosphorylation (OXPHOS) and early postnatal lethality. The TFAM-to-mtDNA ratio varies widely between tissues in these mice and is very high in skeletal muscle leading to strong repression of mtDNA expression and OXPHOS deficiency. In the heart, increased mtDNA copy number results in a near normal TFAM-to-mtDNA ratio and maintained OXPHOS capacity. In liver, induction of LONP1 protease and mitochondrial RNA polymerase expression counteracts the silencing effect of high TFAM levels. TFAM thus acts as a general repressor of mtDNA expression and this effect can be counterbalanced by tissue-specific expression of regulatory factors.
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Affiliation(s)
- Nina A Bonekamp
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Min Jiang
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany.,Zhejiang Provincial Laboratory of Life Sciences and Biomedicine, Key Laboratory of Growth Regulation and Transformation Research of Zhejiang Province, School of Life Sciences, Westlake University, Hangzhou, China
| | - Elisa Motori
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany.,Cologne Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases (CECAD), Cologne, Germany
| | | | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Andrea Mesaros
- Phenotyping Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany .,Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
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68
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Menger KE, Rodríguez-Luis A, Chapman J, Nicholls TJ. Controlling the topology of mammalian mitochondrial DNA. Open Biol 2021; 11:210168. [PMID: 34547213 PMCID: PMC8455175 DOI: 10.1098/rsob.210168] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The genome of mitochondria, called mtDNA, is a small circular DNA molecule present at thousands of copies per human cell. MtDNA is packaged into nucleoprotein complexes called nucleoids, and the density of mtDNA packaging affects mitochondrial gene expression. Genetic processes such as transcription, DNA replication and DNA packaging alter DNA topology, and these topological problems are solved by a family of enzymes called topoisomerases. Within mitochondria, topoisomerases are involved firstly in the regulation of mtDNA supercoiling and secondly in disentangling interlinked mtDNA molecules following mtDNA replication. The loss of mitochondrial topoisomerase activity leads to defects in mitochondrial function, and variants in the dual-localized type IA topoisomerase TOP3A have also been reported to cause human mitochondrial disease. We review the current knowledge on processes that alter mtDNA topology, how mtDNA topology is modulated by the action of topoisomerases, and the consequences of altered mtDNA topology for mitochondrial function and human health.
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Affiliation(s)
- Katja E. Menger
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Alejandro Rodríguez-Luis
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - James Chapman
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Biosciences Institute, Newcastle University, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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69
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Yang Y, Li C, Gu X, Zhen J, Zhu S, Lv T, Wan Q, Liu Y. ING2 Controls Mitochondrial Respiration via Modulating MRPL12 Ubiquitination in Renal Tubular Epithelial Cells. Front Cell Dev Biol 2021; 9:700195. [PMID: 34434929 PMCID: PMC8380824 DOI: 10.3389/fcell.2021.700195] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2021] [Accepted: 06/24/2021] [Indexed: 11/13/2022] Open
Abstract
Mitochondrial injury of tubular epithelial cells (TECs) is the key pathogenic event underlying various kidney diseases and a potential intervening target as well. Our previous study demonstrated that ING2 is ubiquitously expressed at tubulointerstitial area within kidneys, while its role in regulating TEC mitochondrial respiration is not fully elucidated. To clarify the roles of ING2 in mitochondrial homeostasis of TECs and pathogenesis of acute ischemic kidney injury, Western blot, PCR, immunofluorescence, immunoprecipitation, and oxygen consumption rate assay were applied to address the roles of ING2 in modulating mitochondrial respiration. We further complemented these studies with acute ischemic kidney injury both in vitro and in vivo. In vitro study demonstrated ING2 could positively control TEC mitochondrial respiration. Concurrently, both mRNA and protein levels of mtDNA encoded respiratory chain components were altered by ING2, suggesting ING2 could regulate mtDNA transcription. In mechanism, ING2 could regulate the ubiquitination of a newly identified mitochondrial transcription factor MRPL12, thereby modulating its cellular stability and abundance. We also demonstrated ING2-mediated modulation on mtDNA transcription and mitochondrial respiration are involved in serum deprivation induced TEC injuries. Finally, immunohistochemistry study revealed that ING2 expression was significantly altered in kidney biopsies with acute ischemic kidney injury. In vivo study suggested that kidney specific ING2 overexpression could effectively ameliorate acute ischemic kidney injury. Our study demonstrated that ING2 is a crucial modulator of TEC mitochondrial respiration. These findings suggested a unrecognized role of ING2 in TEC mitochondrial energetic homeostasis and a potential intervening target for TEC mitochondrial injury associated pathologies.
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Affiliation(s)
- Ying Yang
- Department of Pharmacy, The Affiliated Hospital of Shandong University of Traditional Chinese Medicine, Jinan, China.,Department of Endocrinology, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China
| | - Chensheng Li
- Department of Gastrointestinal Surgery, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Xia Gu
- School of Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Junhui Zhen
- Department of Pathology, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Suwei Zhu
- School of Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Tingting Lv
- School of Medicine, Cheeloo College of Medicine, Shandong University, Jinan, China
| | - Qiang Wan
- Central Laboratory, Jinan Central Hospital Affiliated to Shandong University, Jinan, China
| | - Yi Liu
- Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital, Cheeloo College of Medicine, Shandong University, Jinan, China.,Department of Pulmonary and Critical Care Medicine, Shandong Provincial Hospital Affiliated to Shandong First Medical University, Jinan, China.,Shandong Key Laboratory of Infectious Respiratory Disease, Jinan, China
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70
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Ravindran S. Profile of Patrick Cramer. Proc Natl Acad Sci U S A 2021; 118:e2111728118. [PMID: 34301909 PMCID: PMC8325307 DOI: 10.1073/pnas.2111728118] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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71
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Human Mitochondrial RNA Processing and Modifications: Overview. Int J Mol Sci 2021; 22:ijms22157999. [PMID: 34360765 PMCID: PMC8348895 DOI: 10.3390/ijms22157999] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Revised: 07/23/2021] [Accepted: 07/24/2021] [Indexed: 01/29/2023] Open
Abstract
Mitochondria, often referred to as the powerhouses of cells, are vital organelles that are present in almost all eukaryotic organisms, including humans. They are the key energy suppliers as the site of adenosine triphosphate production, and are involved in apoptosis, calcium homeostasis, and regulation of the innate immune response. Abnormalities occurring in mitochondria, such as mitochondrial DNA (mtDNA) mutations and disturbances at any stage of mitochondrial RNA (mtRNA) processing and translation, usually lead to severe mitochondrial diseases. A fundamental line of investigation is to understand the processes that occur in these organelles and their physiological consequences. Despite substantial progress that has been made in the field of mtRNA processing and its regulation, many unknowns and controversies remain. The present review discusses the current state of knowledge of RNA processing in human mitochondria and sheds some light on the unresolved issues.
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72
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Oláhová M, Peter B, Szilagyi Z, Diaz-Maldonado H, Singh M, Sommerville EW, Blakely EL, Collier JJ, Hoberg E, Stránecký V, Hartmannová H, Bleyer AJ, McBride KL, Bowden SA, Korandová Z, Pecinová A, Ropers HH, Kahrizi K, Najmabadi H, Tarnopolsky MA, Brady LI, Weaver KN, Prada CE, Õunap K, Wojcik MH, Pajusalu S, Syeda SB, Pais L, Estrella EA, Bruels CC, Kunkel LM, Kang PB, Bonnen PE, Mráček T, Kmoch S, Gorman GS, Falkenberg M, Gustafsson CM, Taylor RW. POLRMT mutations impair mitochondrial transcription causing neurological disease. Nat Commun 2021; 12:1135. [PMID: 33602924 PMCID: PMC7893070 DOI: 10.1038/s41467-021-21279-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Accepted: 12/18/2020] [Indexed: 02/06/2023] Open
Abstract
While >300 disease-causing variants have been identified in the mitochondrial DNA (mtDNA) polymerase γ, no mitochondrial phenotypes have been associated with POLRMT, the RNA polymerase responsible for transcription of the mitochondrial genome. Here, we characterise the clinical and molecular nature of POLRMT variants in eight individuals from seven unrelated families. Patients present with global developmental delay, hypotonia, short stature, and speech/intellectual disability in childhood; one subject displayed an indolent progressive external ophthalmoplegia phenotype. Massive parallel sequencing of all subjects identifies recessive and dominant variants in the POLRMT gene. Patient fibroblasts have a defect in mitochondrial mRNA synthesis, but no mtDNA deletions or copy number abnormalities. The in vitro characterisation of the recombinant POLRMT mutants reveals variable, but deleterious effects on mitochondrial transcription. Together, our in vivo and in vitro functional studies of POLRMT variants establish defective mitochondrial transcription as an important disease mechanism.
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Affiliation(s)
- Monika Oláhová
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Zsolt Szilagyi
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Hector Diaz-Maldonado
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Meenakshi Singh
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Ewen W Sommerville
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emma L Blakely
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Jack J Collier
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Emily Hoberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Viktor Stránecký
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Hana Hartmannová
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Anthony J Bleyer
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
- Section on Nephrology, Wake Forest School of Medicine, Winston-Salem, USA
| | - Kim L McBride
- Center for Cardiovascular and Pulmonary Research, Department of Pediatrics, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, USA
| | - Sasigarn A Bowden
- Division of Endocrinology, Nationwide Children's Hospital, The Ohio State University College of Medicine, Columbus, USA
| | - Zuzana Korandová
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Alena Pecinová
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Hans-Hilger Ropers
- Department of Human Molecular Genetics, Max Planck Institute for Molecular Genetics, Berlin, Germany
- Institute of Human Genetics, University Medical Center of the Johannes Gutenberg University, Mainz, Germany
| | - Kimia Kahrizi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Hossein Najmabadi
- Genetics Research Center, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran
| | - Mark A Tarnopolsky
- Department of Pediatric and Medicines, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Children's Hospital, Hamilton, Canada
| | - Lauren I Brady
- Department of Pediatric and Medicines, Division of Neuromuscular and Neurometabolic Diseases, McMaster University Children's Hospital, Hamilton, Canada
| | - K Nicole Weaver
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Carlos E Prada
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA
- Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
- Department of Pediatrics, Cardiovascular Foundation of Colombia, Floridablanca, Colombia
| | - Katrin Õunap
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
| | - Monica H Wojcik
- Broad Institute of MIT and Harvard, Cambridge, MA, USA
- Divisions of Newborn Medicine and Genetics and Genomics, Department of Pediatrics, Boston Children's Hospital, Boston, MA, USA
| | - Sander Pajusalu
- Department of Clinical Genetics, United Laboratories, Tartu University Hospital, Tartu, Estonia
- Department of Clinical Genetics, Institute of Clinical Medicine, University of Tartu, Tartu, Estonia
- Department of Genetics, Yale University School of Medicine, New Haven, CT, USA
| | - Safoora B Syeda
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Lynn Pais
- Center for Mendelian Genomics, Broad Institute of MIT and Harvard, Cambridge, Massachusetts, USA
| | - Elicia A Estrella
- Division of Genetics & Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Christine C Bruels
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
| | - Louis M Kunkel
- Division of Genetics & Genomics, Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Peter B Kang
- Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL, USA
- Department of Molecular Genetics & Microbiology, and Department of Neurology, University of Florida College of Medicine, Gainesville, FL, USA
- Genetics Institute and Myology Institute, University of Florida, Gainesville, FL, USA
| | - Penelope E Bonnen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, TX, USA
| | - Tomáš Mráček
- Department of Bioenergetics, Institute of Physiology of the Czech Academy of Sciences, Prague, Czech Republic
| | - Stanislav Kmoch
- Research Unit for Rare Diseases, Department of Pediatrics and Adolescent Medicine, First Faculty of Medicine, Charles University, Prague, 120 00, Czech Republic
| | - Gráinne S Gorman
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Robert W Taylor
- Wellcome Centre for Mitochondrial Research, Translational and Clinical Research Institute, The Medical School, Newcastle University, Newcastle upon Tyne, NE2 4HH, UK.
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73
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Ishihara T, Kanon H, Ban-Ishihara R, Ishihara N. Multiple assay systems to analyze the dynamics of mitochondrial nucleoids in living mammalian cells. Biochim Biophys Acta Gen Subj 2021; 1865:129874. [PMID: 33607223 DOI: 10.1016/j.bbagen.2021.129874] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2020] [Revised: 01/18/2021] [Accepted: 02/09/2021] [Indexed: 10/22/2022]
Abstract
BACKGROUND Mitochondria, which play a critical role in energy production by oxidative respiration, are highly dynamic organelles and their double membranes undergo frequent events of fusion and fission. Mitochondria are believed to be derived from the endosymbiosis of proteobacteria, and thus mitochondria still contain their own DNA, mitochondrial DNA (mtDNA). Several copies of mtDNA form mitochondrial nucleoid with DNA-binding proteins. Recently, the morphology and distribution of the mitochondrial membrane and nucleoid were reported to be cooperatively regulated during their dynamic movement. However, the molecular mechanism is unclear, because the involved molecules are poorly understood, and suitable techniques to analyze nucleoid have not been fully developed. RESULTS To solve these issues, we examined the molecular mechanism of nucleoid dynamics by two approaches. First, we constructed a new probe to perform live imaging of nucleoid dynamics using the DNA-binding domain of mitochondrial transcriptional factor A (TFAM) and the photo-convertible fluorescent protein Kikume Green-Red (KikGR). Nucleoids were visualized stably for a long period using the new probe. Second, we searched for nucleoid regulatory factors by small interfering RNA screening using HeLa cells and identified a subset of MARCH family ubiquitin ligases that affect nucleoid morphology. CONCLUSION The factors and probe, reported in this study, would be useful to reveal novel mechanisms of mitochondrial regulation. GENERAL SIGNIFICANCE The mtDNA dynamics should be concerned in the regulation of mitochondrial activity and its quality control, associated with mitochondrial membrane dynamics.
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Affiliation(s)
- Takaya Ishihara
- Department of Biological Sciences, Graduate School of Science, Osaka University, Japan; Department of Protein Biochemistry, Institute of Life Science, Kurume University, Japan.
| | - Hirotaka Kanon
- Department of Biological Sciences, Graduate School of Science, Osaka University, Japan
| | - Reiko Ban-Ishihara
- Department of Protein Biochemistry, Institute of Life Science, Kurume University, Japan
| | - Naotada Ishihara
- Department of Biological Sciences, Graduate School of Science, Osaka University, Japan; Department of Protein Biochemistry, Institute of Life Science, Kurume University, Japan.
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74
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Basu U, Bostwick AM, Das K, Dittenhafer-Reed KE, Patel SS. Structure, mechanism, and regulation of mitochondrial DNA transcription initiation. J Biol Chem 2020; 295:18406-18425. [PMID: 33127643 PMCID: PMC7939475 DOI: 10.1074/jbc.rev120.011202] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Revised: 10/29/2020] [Indexed: 12/14/2022] Open
Abstract
Mitochondria are specialized compartments that produce requisite ATP to fuel cellular functions and serve as centers of metabolite processing, cellular signaling, and apoptosis. To accomplish these roles, mitochondria rely on the genetic information in their small genome (mitochondrial DNA) and the nucleus. A growing appreciation for mitochondria's role in a myriad of human diseases, including inherited genetic disorders, degenerative diseases, inflammation, and cancer, has fueled the study of biochemical mechanisms that control mitochondrial function. The mitochondrial transcriptional machinery is different from nuclear machinery. The in vitro re-constituted transcriptional complexes of Saccharomyces cerevisiae (yeast) and humans, aided with high-resolution structures and biochemical characterizations, have provided a deeper understanding of the mechanism and regulation of mitochondrial DNA transcription. In this review, we will discuss recent advances in the structure and mechanism of mitochondrial transcription initiation. We will follow up with recent discoveries and formative findings regarding the regulatory events that control mitochondrial DNA transcription, focusing on those involved in cross-talk between the mitochondria and nucleus.
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Affiliation(s)
- Urmimala Basu
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA; Graduate School of Biomedical Sciences, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA
| | | | - Kalyan Das
- Department of Microbiology, Immunology, and Transplantation, Rega Institute for Medical Research, KU Leuven, Leuven, Belgium
| | | | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers Robert Wood Johnson Medical School, Piscataway, New Jersey, USA.
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75
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Filograna R, Mennuni M, Alsina D, Larsson NG. Mitochondrial DNA copy number in human disease: the more the better? FEBS Lett 2020; 595:976-1002. [PMID: 33314045 PMCID: PMC8247411 DOI: 10.1002/1873-3468.14021] [Citation(s) in RCA: 207] [Impact Index Per Article: 51.8] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 11/02/2020] [Accepted: 11/26/2020] [Indexed: 12/19/2022]
Abstract
Most of the genetic information has been lost or transferred to the nucleus during the evolution of mitochondria. Nevertheless, mitochondria have retained their own genome that is essential for oxidative phosphorylation (OXPHOS). In mammals, a gene‐dense circular mitochondrial DNA (mtDNA) of about 16.5 kb encodes 13 proteins, which constitute only 1% of the mitochondrial proteome. Mammalian mtDNA is present in thousands of copies per cell and mutations often affect only a fraction of them. Most pathogenic human mtDNA mutations are recessive and only cause OXPHOS defects if present above a certain critical threshold. However, emerging evidence strongly suggests that the proportion of mutated mtDNA copies is not the only determinant of disease but that also the absolute copy number matters. In this review, we critically discuss current knowledge of the role of mtDNA copy number regulation in various types of human diseases, including mitochondrial disorders, neurodegenerative disorders and cancer, and during ageing. We also provide an overview of new exciting therapeutic strategies to directly manipulate mtDNA to restore OXPHOS in mitochondrial diseases.
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Affiliation(s)
- Roberta Filograna
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Mara Mennuni
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - David Alsina
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
| | - Nils-Göran Larsson
- Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.,Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden
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76
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Small-molecule inhibitors of human mitochondrial DNA transcription. Nature 2020; 588:712-716. [PMID: 33328633 DOI: 10.1038/s41586-020-03048-z] [Citation(s) in RCA: 100] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 10/22/2020] [Indexed: 01/31/2023]
Abstract
Altered expression of mitochondrial DNA (mtDNA) occurs in ageing and a range of human pathologies (for example, inborn errors of metabolism, neurodegeneration and cancer). Here we describe first-in-class specific inhibitors of mitochondrial transcription (IMTs) that target the human mitochondrial RNA polymerase (POLRMT), which is essential for biogenesis of the oxidative phosphorylation (OXPHOS) system1-6. The IMTs efficiently impair mtDNA transcription in a reconstituted recombinant system and cause a dose-dependent inhibition of mtDNA expression and OXPHOS in cell lines. To verify the cellular target, we performed exome sequencing of mutagenized cells and identified a cluster of amino acid substitutions in POLRMT that cause resistance to IMTs. We obtained a cryo-electron microscopy (cryo-EM) structure of POLRMT bound to an IMT, which further defined the allosteric binding site near the active centre cleft of POLRMT. The growth of cancer cells and the persistence of therapy-resistant cancer stem cells has previously been reported to depend on OXPHOS7-17, and we therefore investigated whether IMTs have anti-tumour effects. Four weeks of oral treatment with an IMT is well-tolerated in mice and does not cause OXPHOS dysfunction or toxicity in normal tissues, despite inducing a strong anti-tumour response in xenografts of human cancer cells. In summary, IMTs provide a potent and specific chemical biology tool to study the role of mtDNA expression in physiology and disease.
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De Wijngaert B, Sultana S, Singh A, Dharia C, Vanbuel H, Shen J, Vasilchuk D, Martinez SE, Kandiah E, Patel SS, Das K. Cryo-EM Structures Reveal Transcription Initiation Steps by Yeast Mitochondrial RNA Polymerase. Mol Cell 2020; 81:268-280.e5. [PMID: 33278362 DOI: 10.1016/j.molcel.2020.11.016] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Revised: 11/06/2020] [Accepted: 11/09/2020] [Indexed: 01/18/2023]
Abstract
Mitochondrial RNA polymerase (mtRNAP) is crucial in cellular energy production, yet understanding of mitochondrial DNA transcription initiation lags that of bacterial and nuclear DNA transcription. We report structures of two transcription initiation intermediate states of yeast mtRNAP that explain promoter melting, template alignment, DNA scrunching, abortive synthesis, and transition into elongation. In the partially melted initiation complex (PmIC), transcription factor MTF1 makes base-specific interactions with flipped non-template (NT) nucleotides "AAGT" at -4 to -1 positions of the DNA promoter. In the initiation complex (IC), the template in the expanded 7-mer bubble positions the RNA and NTP analog UTPαS, while NT scrunches into an NT loop. The scrunched NT loop is stabilized by the centrally positioned MTF1 C-tail. The IC and PmIC states coexist in solution, revealing a dynamic equilibrium between two functional states. Frequent scrunching/unscruching transitions and the imminent steric clashes of the inflating NT loop and growing RNA:DNA with the C-tail explain abortive synthesis and transition into elongation.
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Affiliation(s)
- Brent De Wijngaert
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Shemaila Sultana
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Anupam Singh
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Chhaya Dharia
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Hans Vanbuel
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Jiayu Shen
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Daniel Vasilchuk
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA
| | - Sergio E Martinez
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium
| | - Eaazhisai Kandiah
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, 38043 Grenoble, France
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, NJ 08854, USA.
| | - Kalyan Das
- Rega Institute for Medical Research, Department of Microbiology, Immunology and Transplantation, KU Leuven, 3000 Leuven, Belgium.
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78
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Rahmel T, Marko B, Nowak H, Bergmann L, Thon P, Rump K, Kreimendahl S, Rassow J, Peters J, Singer M, Adamzik M, Koos B. Mitochondrial dysfunction in sepsis is associated with diminished intramitochondrial TFAM despite its increased cellular expression. Sci Rep 2020; 10:21029. [PMID: 33273525 PMCID: PMC7713186 DOI: 10.1038/s41598-020-78195-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2020] [Accepted: 11/04/2020] [Indexed: 12/14/2022] Open
Abstract
Sepsis is characterized by a dysregulated immune response, metabolic derangements and bioenergetic failure. These alterations are closely associated with a profound and persisting mitochondrial dysfunction. This however occurs despite increased expression of the nuclear-encoded transcription factor A (TFAM) that normally supports mitochondrial biogenesis and functional recovery. Since this paradox may relate to an altered intracellular distribution of TFAM in sepsis, we tested the hypothesis that enhanced extramitochondrial TFAM expression does not translate into increased intramitochondrial TFAM abundance. Accordingly, we prospectively analyzed PBMCs both from septic patients (n = 10) and lipopolysaccharide stimulated PBMCs from healthy volunteers (n = 20). Extramitochondrial TFAM protein expression in sepsis patients was 1.8-fold greater compared to controls (p = 0.001), whereas intramitochondrial TFAM abundance was approximate 80% less (p < 0.001). This was accompanied by lower mitochondrial DNA copy numbers (p < 0.001), mtND1 expression (p < 0.001) and cellular ATP content (p < 0.001) in sepsis patients. These findings were mirrored in lipopolysaccharide stimulated PBMCs taken from healthy volunteers. Furthermore, TFAM-TFB2M protein interaction within the human mitochondrial core transcription initiation complex, was 74% lower in septic patients (p < 0.001). In conclusion, our findings, which demonstrate a diminished mitochondrial TFAM abundance in sepsis and endotoxemia, may help to explain the paradox of lacking bioenergetic recovery despite enhanced TFAM expression.
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Affiliation(s)
- Tim Rahmel
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany.
| | - Britta Marko
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Hartmuth Nowak
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Lars Bergmann
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Patrick Thon
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Katharina Rump
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Sebastian Kreimendahl
- Institut für Biochemie und Pathobiochemie, Abteilung für Zellbiochemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Joachim Rassow
- Institut für Biochemie und Pathobiochemie, Abteilung für Zellbiochemie, Ruhr-Universität Bochum, Bochum, Germany
| | - Jürgen Peters
- Klinik für Anästhesiologie und Intensivmedizin, Universität Duisburg-Essen & Universitätsklinikum Essen, Essen, Germany
| | - Mervyn Singer
- Bloomsbury Institute of Intensive Care Medicine, Division of Medicine, University College London, London, UK
| | - Michael Adamzik
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
| | - Björn Koos
- Klinik für Anästhesiologie, Intensivmedizin und Schmerztherapie, Universitätsklinikum Knappschaftskrankenhaus Bochum, In der Schornau 23-25, 44892, Bochum, Germany
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79
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Fei ZY, Wang WS, Li SF, Zi JJ, Yang L, Liu T, Ao S, Liu QQ, Cui QH, Yu M, Xiong W. High expression of the TEFM gene predicts poor prognosis in hepatocellular carcinoma. J Gastrointest Oncol 2020; 11:1291-1304. [PMID: 33457002 PMCID: PMC7807266 DOI: 10.21037/jgo-20-120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 09/25/2020] [Indexed: 01/10/2023] Open
Abstract
BACKGROUND Mitochondrial transcription elongation factor (TEFM) is an essential molecule that regulates the replication-transcription switch of mitochondrial DNA. TEFM modulates both transcription elongation and RNA processing in mitochondria. The purpose of the present study was to determine the association of TEFM with tumor progression and prognosis in hepatocellular carcinoma (HCC) patients. METHODS The different protein expression level of TEFM among HCC cell lines was detected by Western blotting. The gene expression profiling interactive analysis (GEPIA) was used to dynamically analyze the mRNA expression of TEFM gene in different stages of HCC. The protein and mRNA expression levels of TEFM were detected by immunohistochemistry, Western blotting and qRT-PCR. The mRNA-SeqV2 expression of TEFM and clinical information of HCC patients were downloaded from the TCGA database by using R3.6.3 software. Next, the relationships between the expression level of TEFM and clinicopathological characteristics and the prognostic value of TEFM were analyzed. A Cox regression model was used for multivariate analysis of the factors that affected the prognosis of HCC. Finally, the association between the expression levels of TEFM and other mitochondrial regulatory genes and HCC biomarker genes was analyzed by GEPIA. RESULTS TEFM is upregulated in HCC cell lines compared to noncancerous liver cell line. TEFM protein and mRNA expression levels in HCC tissues were significantly upregulated compared with those in noncancerous liver tissues. In addition, the mRNA expression level of TEFM was significantly correlated with sex, serum AFP level, and vascular invasion (P<0.05). Further analysis showed that high expression level of TEFM was unfavorable in terms of the prognosis of patients with HCC. Cox multivariate regression analysis showed that patient age, vascular invasion, and TEFM expression were independent factors affecting the prognosis of HCC patients (P<0.05). The expression level of the TEFM gene was significantly positively correlated with the expression of multiple mitochondrial regulatory genes and biomarker genes of HCC (P<0.01, R>0). CONCLUSIONS Our findings reveal that TEFM may play an important role in the progression of HCC. More importantly, the elevated expression of TEFM may potentially predict poor overall survival (OS) and disease-free survival (DFS) in patients with HCC.
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Affiliation(s)
- Zai-Yi Fei
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Wei-Si Wang
- College of Basic Medical Sciences, Dali University, Dali, China
- Key Laboratory for Clinical Biochemistry of High Education in Yunnan Province, Dali University, Dali, China
| | - Su-Fen Li
- College of Basic Medical Sciences, Dali University, Dali, China
- Key Laboratory for Clinical Biochemistry of High Education in Yunnan Province, Dali University, Dali, China
| | - Jia-Ji Zi
- College of Basic Medical Sciences, Dali University, Dali, China
| | - Li Yang
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Ting Liu
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Song Ao
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Qian-Qian Liu
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Qing-Hua Cui
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Min Yu
- School of Life Sciences, Yunnan University, Kunming, China
- Key Laboratory for Biochemistry and Molecular Biology of High Education in Yunnan Province, Yunnan University, Kunming, China
| | - Wei Xiong
- College of Basic Medical Sciences, Dali University, Dali, China
- Key Laboratory for Clinical Biochemistry of High Education in Yunnan Province, Dali University, Dali, China
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80
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Bonekamp NA, Peter B, Hillen HS, Felser A, Bergbrede T, Choidas A, Horn M, Unger A, Di Lucrezia R, Atanassov I, Li X, Koch U, Menninger S, Boros J, Habenberger P, Giavalisco P, Cramer P, Denzel MS, Nussbaumer P, Klebl B, Falkenberg M, Gustafsson CM, Larsson NG. Small-molecule inhibitors of human mitochondrial DNA transcription. Nature 2020. [PMID: 33328633 DOI: 10.1038/s41586-020-03048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
Altered expression of mitochondrial DNA (mtDNA) occurs in ageing and a range of human pathologies (for example, inborn errors of metabolism, neurodegeneration and cancer). Here we describe first-in-class specific inhibitors of mitochondrial transcription (IMTs) that target the human mitochondrial RNA polymerase (POLRMT), which is essential for biogenesis of the oxidative phosphorylation (OXPHOS) system1-6. The IMTs efficiently impair mtDNA transcription in a reconstituted recombinant system and cause a dose-dependent inhibition of mtDNA expression and OXPHOS in cell lines. To verify the cellular target, we performed exome sequencing of mutagenized cells and identified a cluster of amino acid substitutions in POLRMT that cause resistance to IMTs. We obtained a cryo-electron microscopy (cryo-EM) structure of POLRMT bound to an IMT, which further defined the allosteric binding site near the active centre cleft of POLRMT. The growth of cancer cells and the persistence of therapy-resistant cancer stem cells has previously been reported to depend on OXPHOS7-17, and we therefore investigated whether IMTs have anti-tumour effects. Four weeks of oral treatment with an IMT is well-tolerated in mice and does not cause OXPHOS dysfunction or toxicity in normal tissues, despite inducing a strong anti-tumour response in xenografts of human cancer cells. In summary, IMTs provide a potent and specific chemical biology tool to study the role of mtDNA expression in physiology and disease.
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Affiliation(s)
- Nina A Bonekamp
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Bradley Peter
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Hauke S Hillen
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Andrea Felser
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | | | | | - Moritz Horn
- Metabolic and Genetic Regulation of Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
- Acus Laboratories, Cologne, Germany
- JLP Health, Vienna, Austria
| | - Anke Unger
- Lead Discovery Center, Dortmund, Germany
| | | | - Ilian Atanassov
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Xinping Li
- Proteomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Uwe Koch
- Lead Discovery Center, Dortmund, Germany
| | | | | | | | - Patrick Giavalisco
- Metabolomics Core Facility, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | - Patrick Cramer
- Department of Molecular Biology, Max Planck Institute for Biophysical Chemistry, Göttingen, Germany
| | - Martin S Denzel
- Metabolic and Genetic Regulation of Ageing, Max Planck Institute for Biology of Ageing, Cologne, Germany
| | | | - Bert Klebl
- Lead Discovery Center, Dortmund, Germany
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, Gothenburg, Sweden.
| | - Nils-Göran Larsson
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, Cologne, Germany.
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden.
- Max Planck Institute for Biology of Ageing-Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm, Sweden.
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81
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Synergism and Antagonism of Two Distinct, but Confused, Nrf1 Factors in Integral Regulation of the Nuclear-to-Mitochondrial Respiratory and Antioxidant Transcription Networks. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2020; 2020:5097109. [PMID: 33376579 PMCID: PMC7744186 DOI: 10.1155/2020/5097109] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 08/09/2020] [Accepted: 10/16/2020] [Indexed: 12/30/2022]
Abstract
There is hitherto no literature available for explaining two distinct, but confused, Nrf1 transcription factors, because they shared the same abbreviations from nuclear factor erythroid 2-related factor 1 (also called Nfe2l1) and nuclear respiratory factor (originally designated α-Pal). Thus, we have here identified that Nfe2l1Nrf1 and α-PalNRF1 exert synergistic and antagonistic roles in integrative regulation of the nuclear-to-mitochondrial respiratory and antioxidant transcription profiles. In mouse embryonic fibroblasts (MEFs), knockout of Nfe2l1−/− leads to substantial decreases in expression levels of α-PalNRF1 and Nfe2l2, together with TFAM (mitochondrial transcription factor A) and other target genes. Similar inhibitory results were determined in Nfe2l2−/− MEFs but with an exception that both GSTa1 and Aldh1a1 were distinguishably upregulated in Nfe2l1−/− MEFs. Such synergistic contributions of Nfe2l1 and Nfe2l2 to the positive regulation of α-PalNRF1 and TFAM were validated in Keap1−/− MEFs. However, human α-PalNRF1 expression was unaltered by hNfe2l1α−/−, hNfe2l2-/-ΔTA, or even hNfe2l1α−/−+siNrf2, albeit TFAM was activated by Nfe2l1 but inhibited by Nfe2l2; such an antagonism occurred in HepG2 cells. Conversely, almost all of mouse Nfe2l1, Nfe2l2, and cotarget genes were downexpressed in α-PalNRF1+/- MEFs. On the contrary, upregulation of human Nfe2l1, Nfe2l2, and relevant reporter genes took place after silencing of α-PalNRF1, but their downregulation occurred upon ectopic expression of α-PalNRF1. Furtherly, Pitx2 (pituitary homeobox 2) was also identified as a direct upstream regulator of Nfe2l1 and TFAM, besides α-PalNRF1. Overall, these across-talks amongst Nfe2l1, Nfe2l2, and α-PalNRF1, along with Pitx2, are integrated from the endoplasmic reticulum towards the nuclear-to-mitochondrial communication for targeting TFAM, in order to finely tune the robust balance of distinct cellular oxidative respiratory and antioxidant gene transcription networks, albeit they differ between the mouse and the human. In addition, it is of crucial importance to note that, in view of such mutual interregulation of these transcription factors, much cautions should be severely taken for us to interpret those relevant experimental results obtained from knockout of Nfe2l1, Nfe2l2, α-Pal or Pitx2, or their gain-of-functional mutants.
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82
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Medini H, Cohen T, Mishmar D. Mitochondria Are Fundamental for the Emergence of Metazoans: On Metabolism, Genomic Regulation, and the Birth of Complex Organisms. Annu Rev Genet 2020; 54:151-166. [PMID: 32857636 DOI: 10.1146/annurev-genet-021920-105545] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Out of many intracellular bacteria, only the mitochondria and chloroplasts abandoned their independence billions of years ago and became endosymbionts within the host eukaryotic cell. Consequently, one cannot grow eukaryotic cells without their mitochondria, and the mitochondria cannot divide outside of the cell, thus reflecting interdependence. Here, we argue that such interdependence underlies the fundamental role of mitochondrial activities in the emergence of metazoans. Several lines of evidence support our hypothesis: (a) Differentiation and embryogenesis rely on mitochondrial function; (b) mitochondrial metabolites are primary precursors for epigenetic modifications (such as methyl and acetyl), which are critical for chromatin remodeling and gene expression, particularly during differentiation and embryogenesis; and (c) mitonuclear coregulation adapted to accommodate both housekeeping and tissue-dependent metabolic needs. We discuss the evolution of the unique mitochondrial genetic system, mitochondrial metabolites, mitonuclear coregulation, and their critical roles in the emergence of metazoans and in human disorders.
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Affiliation(s)
- Hadar Medini
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501 Israel;
| | - Tal Cohen
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501 Israel;
| | - Dan Mishmar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva 8410501 Israel;
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83
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Sohn BK, Basu U, Lee SW, Cho H, Shen J, Deshpande A, Johnson LC, Das K, Patel SS, Kim H. The dynamic landscape of transcription initiation in yeast mitochondria. Nat Commun 2020; 11:4281. [PMID: 32855416 PMCID: PMC7452894 DOI: 10.1038/s41467-020-17793-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2019] [Accepted: 07/14/2020] [Indexed: 01/24/2023] Open
Abstract
Controlling efficiency and fidelity in the early stage of mitochondrial DNA transcription is crucial for regulating cellular energy metabolism. Conformational transitions of the transcription initiation complex must be central for such control, but how the conformational dynamics progress throughout transcription initiation remains unknown. Here, we use single-molecule fluorescence resonance energy transfer techniques to examine the conformational dynamics of the transcriptional system of yeast mitochondria with single-base resolution. We show that the yeast mitochondrial transcriptional complex dynamically transitions among closed, open, and scrunched states throughout the initiation stage. Then abruptly at position +8, the dynamic states of initiation make a sharp irreversible transition to an unbent conformation with associated promoter release. Remarkably, stalled initiation complexes remain in dynamic scrunching and unscrunching states without dissociating the RNA transcript, implying the existence of backtracking transitions with possible regulatory roles. The dynamic landscape of transcription initiation suggests a kinetically driven regulation of mitochondrial transcription.
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Affiliation(s)
- Byeong-Kwon Sohn
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Urmimala Basu
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Seung-Won Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hayoon Cho
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Jiayu Shen
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Aishwarya Deshpande
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Laura C Johnson
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA
| | - Kalyan Das
- Department of Microbiology, Immunology and Transplantation, Rega Institute for Medical Research, KU Leuven, 3000, Leuven, Belgium
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ, 08854, USA.
| | - Hajin Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea.
- Institute for Basic Science, Ulsan, Republic of Korea.
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84
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Chapman J, Ng YS, Nicholls TJ. The Maintenance of Mitochondrial DNA Integrity and Dynamics by Mitochondrial Membranes. Life (Basel) 2020; 10:life10090164. [PMID: 32858900 PMCID: PMC7555930 DOI: 10.3390/life10090164] [Citation(s) in RCA: 33] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/20/2020] [Accepted: 08/23/2020] [Indexed: 12/18/2022] Open
Abstract
Mitochondria are complex organelles that harbour their own genome. Mitochondrial DNA (mtDNA) exists in the form of a circular double-stranded DNA molecule that must be replicated, segregated and distributed around the mitochondrial network. Human cells typically possess between a few hundred and several thousand copies of the mitochondrial genome, located within the mitochondrial matrix in close association with the cristae ultrastructure. The organisation of mtDNA around the mitochondrial network requires mitochondria to be dynamic and undergo both fission and fusion events in coordination with the modulation of cristae architecture. The dysregulation of these processes has profound effects upon mtDNA replication, manifesting as a loss of mtDNA integrity and copy number, and upon the subsequent distribution of mtDNA around the mitochondrial network. Mutations within genes involved in mitochondrial dynamics or cristae modulation cause a wide range of neurological disorders frequently associated with defects in mtDNA maintenance. This review aims to provide an understanding of the biological mechanisms that link mitochondrial dynamics and mtDNA integrity, as well as examine the interplay that occurs between mtDNA, mitochondrial dynamics and cristae structure.
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Affiliation(s)
- James Chapman
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
| | - Yi Shiau Ng
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Translational and Clinical Research Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
| | - Thomas J. Nicholls
- Wellcome Centre for Mitochondrial Research, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK;
- Biosciences Institute, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne NE2 4HH, UK
- Correspondence: (J.C.); (T.J.N.)
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85
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Bostwick AM, Moya GE, Senti ML, Basu U, Shen J, Patel SS, Dittenhafer-Reed KE. Phosphorylation of mitochondrial transcription factor B2 controls mitochondrial DNA binding and transcription. Biochem Biophys Res Commun 2020; 528:580-585. [PMID: 32505352 PMCID: PMC9161741 DOI: 10.1016/j.bbrc.2020.05.141] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 05/20/2020] [Indexed: 11/24/2022]
Abstract
Mammalian cells contain genetic information in two compartments, the nucleus and the mitochondria. Mitochondrial gene expression must be coordinated with nuclear gene expression to respond to cellular energetic needs. To gain insight into the coordination between the nucleus and mitochondria, there is a need to understand the regulation of transcription of mitochondrial DNA (mtDNA). Reversible protein post-translational modifications of the mtDNA transcriptional machinery may be one way to control mtDNA transcription. Here we focus on a member of the mtDNA transcription initiation complex, mitochondrial transcription factor B2 (TFB2M). TFB2M melts mtDNA at the promoter to allow the RNA polymerase (POLRMT) to access the DNA template and initiate transcription. Three phosphorylation sites have been previously identified on TFB2M by mass spectrometry: threonine 184, serine 197, and threonine 313. Phosphomimetics were established at these positions. Proteins were purified and analyzed for their ability to bind mtDNA and initiate transcription in vitro. Our results indicate phosphorylation at threonine 184 and threonine 313 impairs promoter binding and prevents transcription. These findings provide a potential regulatory mechanism of mtDNA transcription and help clarify the importance of protein post-translational modifications in mitochondrial function.
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Affiliation(s)
- Alicia M Bostwick
- Hope College, Department of Chemistry, 35 E. 12th Street, Holland, MI, 49423, United States
| | - Gonzalo E Moya
- Hope College, Department of Chemistry, 35 E. 12th Street, Holland, MI, 49423, United States
| | - Mackenna L Senti
- Hope College, Department of Chemistry, 35 E. 12th Street, Holland, MI, 49423, United States
| | - Urmimala Basu
- Rutgers University, Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, NJ, 08854, United States
| | - Jiayu Shen
- Rutgers University, Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, NJ, 08854, United States
| | - Smita S Patel
- Rutgers University, Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, 683 Hoes Lane, Piscataway, NJ, 08854, United States
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86
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Geng X, Geng Z, Li H, Zhang Y, Li J, Chang H. Over-expression of TFB2M facilitates cell growth and metastasis via activating ROS-Akt-NF-κB signalling in hepatocellular carcinoma. Liver Int 2020; 40:1756-1769. [PMID: 32174027 DOI: 10.1111/liv.14440] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2019] [Revised: 03/10/2020] [Accepted: 03/11/2020] [Indexed: 12/19/2022]
Abstract
BACKGROUND & AIMS Human TFB2M (mitochondrial transcription factor B2) is a key regulator of mitochondria transcription. Our bioinformatic analysis based on the cancer genome atlas (TCGA) data revealed an aberrant over-expression of TFB2M in hepatocellular carcinoma (HCC). However, the functional roles of TFB2M in tumourigenesis remains unexplored, including HCC. METHODS The expression and clinical significance of TFB2M were evaluated by qRT-PCR and western blot analysis. The biological effects and underlying mechanisms of TFB2M in HCC were determined by cell proliferation, colony formation, cell cycle, apoptosis, migration and invasion assays. RESULTS TFB2M was commonly up-regulated in HCC mainly because of the down-regulation of miR101-3p, which significantly correlated with poor survival of HCC patients. Functional experiments revealed that TFB2M significantly promoted HCC cell proliferation, migration and invasion, while inhibited apoptosis in vitro and promoted xenograft tumourigenesis and lung metastasis in nude mice models in vivo. Mechanistically, increased production of reactive oxygen species (ROS) and subsequently activated Akt/NF-κB signalling was found to be involved in the promotion of growth and metastasis by TFB2M in HCC cells. CONCLUSIONS These findings suggest that TFB2M plays a pivotal oncogenic role in HCC cells through activating ROS-Akt-NF-κB signalling pathway.
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Affiliation(s)
- Xilin Geng
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
| | - Zhimin Geng
- Department of Hepatobiliary Surgery, The First Affiliated Hospital of Xi'an Jiaotong University, Xi'an, China
| | - Hui Li
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
| | - Yu Zhang
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
| | - Jibin Li
- State Key Laboratory of Cancer Biology and Experimental, Teaching Center of Basic Medicine, Fourth Military Medical University, Xi'an, China
| | - Hulin Chang
- Department of Hepatobiliary Surgery, Shaanxi Provincial People's Hospital, Xi'an, China
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87
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Recurrent horizontal transfer identifies mitochondrial positive selection in a transmissible cancer. Nat Commun 2020; 11:3059. [PMID: 32546718 PMCID: PMC7297733 DOI: 10.1038/s41467-020-16765-w] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 05/26/2020] [Indexed: 01/27/2023] Open
Abstract
Autonomous replication and segregation of mitochondrial DNA (mtDNA) creates the potential for evolutionary conflict driven by emergence of haplotypes under positive selection for 'selfish' traits, such as replicative advantage. However, few cases of this phenomenon arising within natural populations have been described. Here, we survey the frequency of mtDNA horizontal transfer within the canine transmissible venereal tumour (CTVT), a contagious cancer clone that occasionally acquires mtDNA from its hosts. Remarkably, one canine mtDNA haplotype, A1d1a, has repeatedly and recently colonised CTVT cells, recurrently replacing incumbent CTVT haplotypes. An A1d1a control region polymorphism predicted to influence transcription is fixed in the products of an A1d1a recombination event and occurs somatically on other CTVT mtDNA backgrounds. We present a model whereby 'selfish' positive selection acting on a regulatory variant drives repeated fixation of A1d1a within CTVT cells.
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88
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Mitochondrial OXPHOS Biogenesis: Co-Regulation of Protein Synthesis, Import, and Assembly Pathways. Int J Mol Sci 2020; 21:ijms21113820. [PMID: 32481479 PMCID: PMC7312649 DOI: 10.3390/ijms21113820] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Revised: 05/21/2020] [Accepted: 05/25/2020] [Indexed: 02/07/2023] Open
Abstract
The assembly of mitochondrial oxidative phosphorylation (OXPHOS) complexes is an intricate process, which—given their dual-genetic control—requires tight co-regulation of two evolutionarily distinct gene expression machineries. Moreover, fine-tuning protein synthesis to the nascent assembly of OXPHOS complexes requires regulatory mechanisms such as translational plasticity and translational activators that can coordinate mitochondrial translation with the import of nuclear-encoded mitochondrial proteins. The intricacy of OXPHOS complex biogenesis is further evidenced by the requirement of many tightly orchestrated steps and ancillary factors. Early-stage ancillary chaperones have essential roles in coordinating OXPHOS assembly, whilst late-stage assembly factors—also known as the LYRM (leucine–tyrosine–arginine motif) proteins—together with the mitochondrial acyl carrier protein (ACP)—regulate the incorporation and activation of late-incorporating OXPHOS subunits and/or co-factors. In this review, we describe recent discoveries providing insights into the mechanisms required for optimal OXPHOS biogenesis, including the coordination of mitochondrial gene expression with the availability of nuclear-encoded factors entering via mitochondrial protein import systems.
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89
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Basu U, Mishra N, Farooqui M, Shen J, Johnson LC, Patel SS. The C-terminal tails of the mitochondrial transcription factors Mtf1 and TFB2M are part of an autoinhibitory mechanism that regulates DNA binding. J Biol Chem 2020; 295:6823-6830. [PMID: 32241911 DOI: 10.1074/jbc.ra120.013338] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 03/31/2020] [Indexed: 11/06/2022] Open
Abstract
The structurally homologous Mtf1 and TFB2M proteins serve as transcription initiation factors of mitochondrial RNA polymerases in Saccharomyces cerevisiae and humans, respectively. These transcription factors directly interact with the nontemplate strand of the transcription bubble to drive promoter melting. Given the key roles of Mtf1 and TFB2M in promoter-specific transcription initiation, it can be expected that the DNA binding activity of the mitochondrial transcription factors is regulated to prevent DNA binding at inappropriate times. However, little information is available on how mitochondrial DNA transcription is regulated. While studying C-terminal (C-tail) deletion mutants of Mtf1 and TFB2M, we stumbled upon a finding that suggested that the flexible C-tail region of these factors autoregulates their DNA binding activity. Quantitative DNA binding studies with fluorescence anisotropy-based titrations revealed that Mtf1 with an intact C-tail has no affinity for DNA but deletion of the C-tail greatly increases Mtf1's DNA binding affinity. Similar observations were made with TFB2M, although autoinhibition by the C-tail of TFB2M was not as complete as in Mtf1. Analysis of available TFB2M structures disclosed that the C-tail engages in intramolecular interactions with the DNA binding groove in the free factor, which, we propose, inhibits its DNA binding activity. Further experiments showed that RNA polymerase relieves this autoinhibition by interacting with the C-tail and engaging it in complex formation. In conclusion, our biochemical and structural analyses reveal autoinhibitory and activation mechanisms of mitochondrial transcription factors that regulate their DNA binding activities and aid in specific assembly of transcription initiation complexes.
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Affiliation(s)
- Urmimala Basu
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854.,Graduate School of Biomedical Sciences, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Nandini Mishra
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854.,Undergraduate Honors Scholars Program, School of Arts and Sciences, Rutgers University, New Brunswick, New Jersey 08901
| | - Mohammed Farooqui
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854.,Undergraduate Honors Scholars Program, School of Arts and Sciences, Rutgers University, New Brunswick, New Jersey 08901
| | - Jiayu Shen
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854.,Graduate School of Biomedical Sciences, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Laura C Johnson
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854.,Graduate School of Biomedical Sciences, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Robert Wood Johnson Medical School, Rutgers University, Piscataway, New Jersey 08854
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90
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Basu U, Lee SW, Deshpande A, Shen J, Sohn BK, Cho H, Kim H, Patel SS. The C-terminal tail of the yeast mitochondrial transcription factor Mtf1 coordinates template strand alignment, DNA scrunching and timely transition into elongation. Nucleic Acids Res 2020; 48:2604-2620. [PMID: 31980825 PMCID: PMC7049685 DOI: 10.1093/nar/gkaa040] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Revised: 12/20/2019] [Accepted: 01/13/2020] [Indexed: 11/16/2022] Open
Abstract
Mitochondrial RNA polymerases depend on initiation factors, such as TFB2M in humans and Mtf1 in yeast Saccharomyces cerevisiae, for promoter-specific transcription. These factors drive the melting of promoter DNA, but how they support RNA priming and growth was not understood. We show that the flexible C-terminal tails of Mtf1 and TFB2M play a crucial role in RNA priming by aiding template strand alignment in the active site for high-affinity binding of the initiating nucleotides. Using single-molecule fluorescence approaches, we show that the Mtf1 C-tail promotes RNA growth during initiation by stabilizing the scrunched DNA conformation. Additionally, due to its location in the path of the nascent RNA, the C-tail of Mtf1 serves as a sensor of the RNA-DNA hybrid length. Initially, steric clashes of the Mtf1 C-tail with short RNA-DNA hybrids cause abortive synthesis but clashes with longer RNA-DNA trigger conformational changes for the timely release of the promoter DNA to commence the transition into elongation. The remarkable similarities in the functions of the C-tail and σ3.2 finger of the bacterial factor suggest mechanistic convergence of a flexible element in the transcription initiation factor that engages the DNA template for RNA priming and growth and disengages when needed to generate the elongation complex.
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Affiliation(s)
- Urmimala Basu
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- Graduate School of Biomedical Sciences at Robert Wood Johnson Medical School of the Rutgers University, USA
| | - Seung-Won Lee
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Aishwarya Deshpande
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
| | - Jiayu Shen
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
- Graduate School of Biomedical Sciences at Robert Wood Johnson Medical School of the Rutgers University, USA
| | - Byeong-Kwon Sohn
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hayoon Cho
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
| | - Hajin Kim
- School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, Republic of Korea
- Center for Genomic Integrity, Institute for Basic Science, Ulsan, Republic of Korea
| | - Smita S Patel
- Department of Biochemistry and Molecular Biology, Rutgers University, Robert Wood Johnson Medical School, Piscataway, NJ 08854, USA
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91
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Cuppari A, Fernández-Millán P, Battistini F, Tarrés-Solé A, Lyonnais S, Iruela G, Ruiz-López E, Enciso Y, Rubio-Cosials A, Prohens R, Pons M, Alfonso C, Tóth K, Rivas G, Orozco M, Solà M. DNA specificities modulate the binding of human transcription factor A to mitochondrial DNA control region. Nucleic Acids Res 2020; 47:6519-6537. [PMID: 31114891 PMCID: PMC6614842 DOI: 10.1093/nar/gkz406] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Revised: 04/30/2019] [Accepted: 05/15/2019] [Indexed: 12/18/2022] Open
Abstract
Human mitochondrial DNA (h-mtDNA) codes for 13 subunits of the oxidative phosphorylation pathway, the essential route that produces ATP. H-mtDNA transcription and replication depends on the transcription factor TFAM, which also maintains and compacts this genome. It is well-established that TFAM activates the mtDNA promoters LSP and HSP1 at the mtDNA control region where DNA regulatory elements cluster. Previous studies identified still uncharacterized, additional binding sites at the control region downstream from and slightly similar to LSP, namely sequences X and Y (Site-X and Site-Y) (Fisher et al., Cell 50, pp 247-258, 1987). Here, we explore TFAM binding at these two sites and compare them to LSP by multiple experimental and in silico methods. Our results show that TFAM binding is strongly modulated by the sequence-dependent properties of Site-X, Site-Y and LSP. The high binding versatility of Site-Y or the considerable stiffness of Site-X tune TFAM interactions. In addition, we show that increase in TFAM/DNA complex concentration induces multimerization, which at a very high concentration triggers disruption of preformed complexes. Therefore, our results suggest that mtDNA sequences induce non-uniform TFAM binding and, consequently, direct an uneven distribution of TFAM aggregation sites during the essential process of mtDNA compaction.
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Affiliation(s)
- Anna Cuppari
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Pablo Fernández-Millán
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Federica Battistini
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain
| | - Aleix Tarrés-Solé
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Sébastien Lyonnais
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Guillermo Iruela
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Elena Ruiz-López
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Yuliana Enciso
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Anna Rubio-Cosials
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
| | - Rafel Prohens
- Unitat de Polimorfisme i Calorimetria, Centres Científics i Tecnològics, University of Barcelona, 08028 Barcelona, Spain
| | - Miquel Pons
- BioNMR Laboratory, Inorganic and Organic Chemistry Department, Universitat de Barcelona, 08028 Barcelona, Spain
| | - Carlos Alfonso
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Katalin Tóth
- Deutsches Krebsforschungszentrum, Division Biophysics of Macromolecules, Heidelberg, Germany
| | - Germán Rivas
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas (CSIC), 28040 Madrid, Spain
| | - Modesto Orozco
- Institute for Research in Biomedicine (IRB Barcelona), The Barcelona Institute of Science and Technology, 08028 Barcelona, Spain.,Department of Biochemistry and Biomedicine, University of Barcelona, Barcelona 08028, Spain
| | - Maria Solà
- Structural MitoLab, Structural Biology Department, Maria de Maeztu Unit of Excellence, Molecular Biology Institute Barcelona (IBMB-CSIC), 08028 Barcelona, Spain
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92
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Knockdown of TFAM in Tumor Cells Retarded Autophagic Flux through Regulating p53 Acetylation and PISD Expression. Cancers (Basel) 2020; 12:cancers12020493. [PMID: 32093281 PMCID: PMC7072172 DOI: 10.3390/cancers12020493] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 02/17/2020] [Accepted: 02/19/2020] [Indexed: 12/28/2022] Open
Abstract
Mitochondrial transcription factor A (TFAM) is required for mitochondrial DNA replication and transcription, which are essential for mitochondrial biogenesis. Previous studies reported that depleting mitochondrial functions by genetic deletion of TFAM impaired autophagic activities. However, the underlying mechanisms remain largely unknown. In the current study, we identified that knockdown of TFAM repressed the synthesis of autophagy bio-marker LC3-II in tumor cells and decreased the expression of phosphatidyl-serine decarboxylase (PISD). Besides, downregulation of PISD with siRNA reduced the level of LC3-II, indicating that depletion of TFAM retarded autophagy via inhibiting PISD expression. Furthermore, it was found that the tumor repressor p53 could stimulate the transcription and expression of PISD by binding the PISD enhancer. Additionally, the protein stability and transcriptional activity of p53 in TFAM knockdown tumor cells was attenuated, and this was associated with decreased acetylation, especially the acetylation of lysine 382 of p53. Finally, we identified that TFAM knockdown increased the NAD+/NADH ratio in tumor cells. This led to the upregulation of Sirtuin1 (SIRT1), a NAD-dependent protein deacetylase, to deacetylate p53 and attenuated its transcriptional activation on PISD. In summary, our study discovered a new mechanism regarding disturbed autophagy in tumor cells with mitochondrial dysfunction due to the depletion of TFAM.
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93
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Mierzwa BE. Communicating scientific concepts through art. J Vis Commun Med 2019; 43:85-90. [PMID: 31858847 DOI: 10.1080/17453054.2019.1700783] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Beata E Mierzwa
- Ludwig Institute for Cancer Research, San Diego; Department of Cellular and Molecular Medicine, University of California, San Diego, USA
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94
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Mishmar D, Levin R, Naeem MM, Sondheimer N. Higher Order Organization of the mtDNA: Beyond Mitochondrial Transcription Factor A. Front Genet 2019; 10:1285. [PMID: 31998357 PMCID: PMC6961661 DOI: 10.3389/fgene.2019.01285] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2019] [Accepted: 11/21/2019] [Indexed: 01/09/2023] Open
Abstract
The higher order organization of eukaryotic and prokaryotic genomes is pivotal in the regulation of gene expression. Specifically, chromatin accessibility in eukaryotes and nucleoid accessibility in bacteria are regulated by a cohort of proteins to alter gene expression in response to diverse physiological conditions. By contrast, prior studies have suggested that the mitochondrial genome (mtDNA) is coated solely by mitochondrial transcription factor A (TFAM), whose increased cellular concentration was proposed to be the major determinant of mtDNA packaging in the mitochondrial nucleoid. Nevertheless, recent analysis of DNase-seq and ATAC-seq experiments from multiple human and mouse samples suggest gradual increase in mtDNA occupancy during the course of embryonic development to generate a conserved footprinting pattern which correlate with sites that have low TFAM occupancy in vivo (ChIP-seq) and tend to adopt G-quadruplex structures. These findings, along with recent identification of mtDNA binding by known modulators of chromatin accessibility such as MOF, suggest that mtDNA higher order organization is generated by cross talk with the nuclear regulatory system, may have a role in mtDNA regulation, and is more complex than once thought.
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Affiliation(s)
- Dan Mishmar
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Rotem Levin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Mansur M Naeem
- Institute of Medical Sciences and the Department of Paediatrics, The University of Toronto, Toronto, ON, Canada
| | - Neal Sondheimer
- Institute of Medical Sciences and the Department of Paediatrics, The University of Toronto, Toronto, ON, Canada
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95
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Kotrys AV, Szczesny RJ. Mitochondrial Gene Expression and Beyond-Novel Aspects of Cellular Physiology. Cells 2019; 9:cells9010017. [PMID: 31861673 PMCID: PMC7017415 DOI: 10.3390/cells9010017] [Citation(s) in RCA: 40] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 12/15/2019] [Accepted: 12/17/2019] [Indexed: 02/06/2023] Open
Abstract
Mitochondria are peculiar organelles whose proper function depends on the crosstalk between two genomes, mitochondrial and nuclear. The human mitochondrial genome (mtDNA) encodes only 13 proteins; nevertheless, its proper expression is essential for cellular homeostasis, as mtDNA-encoded proteins are constituents of mitochondrial respiratory complexes. In addition, mtDNA expression results in the production of RNA molecules, which influence cell physiology once released from the mitochondria into the cytoplasm. As a result, dysfunctions of mtDNA expression may lead to pathologies in humans. Here, we review the mechanisms of mitochondrial gene expression with a focus on recent findings in the field. We summarize the complex turnover of mitochondrial transcripts and present an increasing body of evidence indicating new functions of mitochondrial transcripts. We discuss mitochondrial gene regulation in different cellular contexts, focusing on stress conditions. Finally, we highlight the importance of emerging aspects of mitochondrial gene regulation in human health and disease.
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96
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Liu X, Shen S, Wu P, Li F, Liu X, Wang C, Gong Q, Wu J, Yao X, Zhang H, Shi Y. Structural insights into dimethylation of 12S rRNA by TFB1M: indispensable role in translation of mitochondrial genes and mitochondrial function. Nucleic Acids Res 2019; 47:7648-7665. [PMID: 31251801 PMCID: PMC6698656 DOI: 10.1093/nar/gkz505] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Revised: 05/16/2019] [Accepted: 06/12/2019] [Indexed: 12/15/2022] Open
Abstract
Mitochondria are essential molecular machinery for the maintenance of cellular energy supply by the oxidative phosphorylation system (OXPHOS). Mitochondrial transcription factor B1 (TFB1M) is a dimethyltransferase that maintains mitochondrial homeostasis by catalyzing dimethylation of two adjacent adenines located in helix45 (h45) of 12S rRNA. This m62A modification is indispensable for the assembly and maturation of human mitochondrial ribosomes. However, both the mechanism of TFB1M catalysis and the precise function of TFB1M in mitochondrial homeostasis are unknown. Here we report the crystal structures of a ternary complex of human (hs) TFB1M–h45–S-adenosyl-methionine and a binary complex hsTFB1M–h45. The structures revealed a distinct mode of hsTFB1M interaction with its rRNA substrate and with the initial enzymatic state involved in m62A modification. The suppression of hsTFB1M protein level or the overexpression of inactive hsTFB1M mutants resulted in decreased ATP production and reduced expression of components of the mitochondrial OXPHOS without affecting transcription of the corresponding genes and their localization to the mitochondria. Therefore, hsTFB1M regulated the translation of mitochondrial genes rather than their transcription via m62A modification in h45.
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Affiliation(s)
- Xiaodan Liu
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Shengqi Shen
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Pengzhi Wu
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Fudong Li
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Xing Liu
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Chongyuan Wang
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Qingguo Gong
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Jihui Wu
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Xuebiao Yao
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Huafeng Zhang
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
| | - Yunyu Shi
- School of Life Sciences, University of Science & Technology of China, Hefei 230027, China.,Hefei National Laboratory for Physical Sciences at the Microscale, University of Science & Technology of China, Hefei 230027, China
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97
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Abstract
Torsional stress plays a vital role in many genomic transactions, including replication and transcription, and often results in underwound (negatively supercoiled) DNA. Here, we present a single-molecule method, termed Optical DNA Supercoiling (ODS), that advances our ability to study negatively supercoiled DNA. Since ODS is based on dual-trap optical tweezers, it is compatible with a wide range of functionalities that are difficult to combine with traditional methods of DNA twist control. This includes the ability to image supercoiled DNA with fluorescence microscopy and move the supercoiled substrate rapidly between different buffer/protein solutions. We demonstrate that ODS yields unique and important insights into both the biomechanical properties of negatively supercoiled DNA and the dynamics of DNA–protein interactions on underwound DNA. Cellular DNA is regularly subject to torsional stress during genomic processes, such as transcription and replication, resulting in a range of supercoiled DNA structures. For this reason, methods to prepare and study supercoiled DNA at the single-molecule level are widely used, including magnetic, angular-optical, micropipette, and magneto-optical tweezers. However, it is currently challenging to combine DNA supercoiling control with spatial manipulation and fluorescence microscopy. This limits the ability to study complex and dynamic interactions of supercoiled DNA. Here we present a single-molecule assay that can rapidly and controllably generate negatively supercoiled DNA using a standard dual-trap optical tweezers instrument. This method, termed Optical DNA Supercoiling (ODS), uniquely combines the ability to study supercoiled DNA using force spectroscopy, fluorescence imaging of the whole DNA, and rapid buffer exchange. The technique can be used to generate a wide range of supercoiled states, with between <5 and 70% lower helical twist than nonsupercoiled DNA. Highlighting the versatility of ODS, we reveal previously unobserved effects of ionic strength and sequence on the structural state of underwound DNA. Next, we demonstrate that ODS can be used to directly visualize and quantify protein dynamics on supercoiled DNA. We show that the diffusion of the mitochondrial transcription factor TFAM can be significantly hindered by local regions of underwound DNA. This finding suggests a mechanism by which supercoiling could regulate mitochondrial transcription in vivo. Taken together, we propose that ODS represents a powerful method to study both the biophysical properties and biological interactions of negatively supercoiled DNA.
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98
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Brieba LG. Structure-Function Analysis Reveals the Singularity of Plant Mitochondrial DNA Replication Components: A Mosaic and Redundant System. PLANTS 2019; 8:plants8120533. [PMID: 31766564 PMCID: PMC6963530 DOI: 10.3390/plants8120533] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Revised: 11/18/2019] [Accepted: 11/19/2019] [Indexed: 02/06/2023]
Abstract
Plants are sessile organisms, and their DNA is particularly exposed to damaging agents. The integrity of plant mitochondrial and plastid genomes is necessary for cell survival. During evolution, plants have evolved mechanisms to replicate their mitochondrial genomes while minimizing the effects of DNA damaging agents. The recombinogenic character of plant mitochondrial DNA, absence of defined origins of replication, and its linear structure suggest that mitochondrial DNA replication is achieved by a recombination-dependent replication mechanism. Here, I review the mitochondrial proteins possibly involved in mitochondrial DNA replication from a structural point of view. A revision of these proteins supports the idea that mitochondrial DNA replication could be replicated by several processes. The analysis indicates that DNA replication in plant mitochondria could be achieved by a recombination-dependent replication mechanism, but also by a replisome in which primers are synthesized by three different enzymes: Mitochondrial RNA polymerase, Primase-Helicase, and Primase-Polymerase. The recombination-dependent replication model and primers synthesized by the Primase-Polymerase may be responsible for the presence of genomic rearrangements in plant mitochondria.
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Affiliation(s)
- Luis Gabriel Brieba
- Laboratorio Nacional de Genómica para la Biodiversidad, Centro de Investigación y de Estudios Avanzados del IPN, Apartado Postal 629, Irapuato, Guanajuato C.P. 36821, Mexico
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Ježek P, Dlasková A. Dynamic of mitochondrial network, cristae, and mitochondrial nucleoids in pancreatic β-cells. Mitochondrion 2019; 49:245-258. [DOI: 10.1016/j.mito.2019.06.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/21/2019] [Accepted: 06/24/2019] [Indexed: 12/17/2022]
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100
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Nicholls TJ, Spåhr H, Jiang S, Siira SJ, Koolmeister C, Sharma S, Kauppila JHK, Jiang M, Kaever V, Rackham O, Chabes A, Falkenberg M, Filipovska A, Larsson NG, Gustafsson CM. Dinucleotide Degradation by REXO2 Maintains Promoter Specificity in Mammalian Mitochondria. Mol Cell 2019; 76:784-796.e6. [PMID: 31588022 PMCID: PMC6900737 DOI: 10.1016/j.molcel.2019.09.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Revised: 07/12/2019] [Accepted: 09/04/2019] [Indexed: 12/12/2022]
Abstract
Oligoribonucleases are conserved enzymes that degrade short RNA molecules of up to 5 nt in length and are assumed to constitute the final stage of RNA turnover. Here we demonstrate that REXO2 is a specialized dinucleotide-degrading enzyme that shows no preference between RNA and DNA dinucleotide substrates. A heart- and skeletal-muscle-specific knockout mouse displays elevated dinucleotide levels and alterations in gene expression patterns indicative of aberrant dinucleotide-primed transcription initiation. We find that dinucleotides act as potent stimulators of mitochondrial transcription initiation in vitro. Our data demonstrate that increased levels of dinucleotides can be used to initiate transcription, leading to an increase in transcription levels from both mitochondrial promoters and other, nonspecific sequence elements in mitochondrial DNA. Efficient RNA turnover by REXO2 is thus required to maintain promoter specificity and proper regulation of transcription in mammalian mitochondria.
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Affiliation(s)
- Thomas J Nicholls
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Henrik Spåhr
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany; Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Shan Jiang
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Stefan J Siira
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; Centre for Medical Research, The University of Western Australia, Nedlands, WA 6009, Australia
| | - Camilla Koolmeister
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden
| | - Sushma Sharma
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Johanna H K Kauppila
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Min Jiang
- Department of Mitochondrial Biology, Max Planck Institute for Biology of Ageing, 50931 Cologne, Germany
| | - Volkhard Kaever
- Research Core Unit Metabolomics, Hannover Medical School, 30625 Hannover, Germany
| | - Oliver Rackham
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; School of Pharmacy and Biomedical Sciences, Curtin University, Bentley, WA 6102, Australia; Curtin Health Innovation Research Institute, Curtin University, Bentley, WA 6102, Australia
| | - Andrei Chabes
- Department of Medical Biochemistry and Biophysics, Umeå University, Umeå 901 87, Sweden
| | - Maria Falkenberg
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden
| | - Aleksandra Filipovska
- Harry Perkins Institute of Medical Research, Nedlands, WA 6009, Australia; School of Molecular Sciences, The University of Western Australia, Nedlands, WA, Australia
| | - Nils-Göran Larsson
- Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm 17177, Sweden; Max Planck Institute for Biology of Ageing - Karolinska Institutet Laboratory, Karolinska Institutet, Stockholm 17177, Sweden.
| | - Claes M Gustafsson
- Department of Medical Biochemistry and Cell Biology, University of Gothenburg, PO Box 440, Gothenburg 405 30, Sweden.
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