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Ferreira T, Rodriguez S. Mitochondrial DNA: Inherent Complexities Relevant to Genetic Analyses. Genes (Basel) 2024; 15:617. [PMID: 38790246 PMCID: PMC11121663 DOI: 10.3390/genes15050617] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2024] [Revised: 05/09/2024] [Accepted: 05/10/2024] [Indexed: 05/26/2024] Open
Abstract
Mitochondrial DNA (mtDNA) exhibits distinct characteristics distinguishing it from the nuclear genome, necessitating specific analytical methods in genetic studies. This comprehensive review explores the complex role of mtDNA in a variety of genetic studies, including genome-wide, epigenome-wide, and phenome-wide association studies, with a focus on its implications for human traits and diseases. Here, we discuss the structure and gene-encoding properties of mtDNA, along with the influence of environmental factors and epigenetic modifications on its function and variability. Particularly significant are the challenges posed by mtDNA's high mutation rate, heteroplasmy, and copy number variations, and their impact on disease susceptibility and population genetic analyses. The review also highlights recent advances in methodological approaches that enhance our understanding of mtDNA associations, advocating for refined genetic research techniques that accommodate its complexities. By providing a comprehensive overview of the intricacies of mtDNA, this paper underscores the need for an integrated approach to genetic studies that considers the unique properties of mitochondrial genetics. Our findings aim to inform future research and encourage the development of innovative methodologies to better interpret the broad implications of mtDNA in human health and disease.
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Affiliation(s)
- Tomas Ferreira
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- Department of Clinical Neurosciences, School of Clinical Medicine, University of Cambridge, Cambridge CB2 0SL, UK
| | - Santiago Rodriguez
- Bristol Medical School, University of Bristol, Bristol BS8 1UD, UK
- MRC Integrative Epidemiology Unit, Population Health Sciences, Bristol Medical School, University of Bristol, Bristol BS8 1QU, UK
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2
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Biró B, Gál Z, Fekete Z, Klecska E, Hoffmann OI. Mitochondrial genome plasticity of mammalian species. BMC Genomics 2024; 25:278. [PMID: 38486136 PMCID: PMC10941376 DOI: 10.1186/s12864-024-10201-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2023] [Accepted: 03/08/2024] [Indexed: 03/17/2024] Open
Abstract
There is an ongoing process in which mitochondrial sequences are being integrated into the nuclear genome. The importance of these sequences has already been revealed in cancer biology, forensic, phylogenetic studies and in the evolution of the eukaryotic genetic information. Human and numerous model organisms' genomes were described from those sequences point of view. Furthermore, recent studies were published on the patterns of these nuclear localised mitochondrial sequences in different taxa.However, the results of the previously released studies are difficult to compare due to the lack of standardised methods and/or using few numbers of genomes. Therefore, in this paper our primary goal is to establish a uniform mining pipeline to explore these nuclear localised mitochondrial sequences.Our results show that the frequency of several repetitive elements is higher in the flanking regions of these sequences than expected. A machine learning model reveals that the flanking regions' repetitive elements and different structural characteristics are highly influential during the integration process.In this paper, we introduce a general mining pipeline for all mammalian genomes. The workflow is publicly available and is believed to serve as a validated baseline for future research in this field. We confirm the widespread opinion, on - as to our current knowledge - the largest dataset, that structural circumstances and events corresponding to repetitive elements are highly significant. An accurate model has also been trained to predict these sequences and their corresponding flanking regions.
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Affiliation(s)
- Bálint Biró
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary.
- Group BM, Data Insights Team, _VOIS, Kerepesi str. 35, 1087, Budapest, Hungary.
| | - Zoltán Gál
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary
| | - Zsófia Fekete
- Department of Genetics and Genomics, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary
| | - Eszter Klecska
- FamiCord Group, Krio Institute, Kelemen László str, 1026, Budapest, Hungary
| | - Orsolya Ivett Hoffmann
- Agribiotechnology and Precision Breeding for Food Security National Laboratory, Department of Animal Biotechnology, Institute of Genetics and Biotechnology, Hungarian University of Agriculture and Life Sciences, Szent-Györgyi Albert str. 4, 2100, Gödöllő, Hungary.
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3
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Harutyunyan T. The known unknowns of mitochondrial carcinogenesis: de novo NUMTs and intercellular mitochondrial transfer. Mutagenesis 2024; 39:1-12. [PMID: 37804235 DOI: 10.1093/mutage/gead031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2023] [Accepted: 10/05/2023] [Indexed: 10/09/2023] Open
Abstract
The translocation of mitochondrial DNA (mtDNA) sequences into the nuclear genome, resulted in the occurrence of nuclear sequences of mitochondrial origin (NUMTs) which can be detected in nearly all sequenced eukaryotes. However, de novo mtDNA insertions can contribute to the development of pathological conditions including cancer. Recent data indicate that de novo mtDNA translocation into chromosomes can occur due to genotoxic influence of DNA double-strand break-inducing environmental mutagens. This confirms the hypothesis of the involvement of genome instability in the occurrence of mtDNA fragments in chromosomes. Mounting evidence indicates that mitochondria can be transferred from normal cells to cancer cells and recover cellular respiration. These exchanged mitochondria can facilitate cancer progression and metastasis. This review article provides a comprehensive overview of the potential carcinogenicity of mtDNA insertions, and the relevance of mtDNA escape in cancer progression, metastasis, and treatment resistance in humans. Potential molecular targets involved in mtDNA escape and exchange of mitochondria that can be of possible clinical benefits are presented and discussed. Understanding these processes could lead to improved diagnostic approaches, novel therapeutic strategies, and a deeper understanding of the intricate relationship between mitochondria, nuclear DNA, and cancer biology.
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Affiliation(s)
- Tigran Harutyunyan
- Department of Genetics and Cytology, Yerevan State University, 1 Alex Manoogian, 0025 Yerevan, Armenia
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4
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Yu Y, Wang X, Fox J, Yu R, Thakre P, McCauley B, Nikoloutsos N, Li Q, Hastings PJ, Dang W, Chen K, Ira G. Yeast EndoG prevents genome instability by degrading cytoplasmic DNA. RESEARCH SQUARE 2024:rs.3.rs-3641411. [PMID: 38260641 PMCID: PMC10802722 DOI: 10.21203/rs.3.rs-3641411/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/24/2024]
Abstract
In metazoans release of mitochondrial DNA or retrotransposon cDNA to cytoplasm can cause sterile inflammation and disease 1. Cytoplasmic nucleases degrade these DNA species to limit inflammation 2,3. It remains unknown whether degradation these DNA also prevents nuclear genome instability. To address this question, we decided to identify the nuclease regulating transfer of these cytoplasmic DNA species to the nucleus. We used an amplicon sequencing-based method in yeast enabling analysis of millions of DSB repair products. Nuclear mtDNA (NUMTs) and retrotransposon cDNA insertions increase dramatically in nondividing stationary phase cells. Yeast EndoG (Nuc1) nuclease limits insertions of cDNA and transfer of very long mtDNA (>10 kb) that forms unstable circles or rarely insert in the genome, but it promotes formation of short NUMTs (~45-200 bp). Nuc1 also regulates transfer of cytoplasmic DNA to nucleus in aging or during meiosis. We propose that Nuc1 preserves genome stability by degrading retrotransposon cDNA and long mtDNA, while short NUMTs can originate from incompletely degraded mtDNA. This work suggests that nucleases eliminating cytoplasmic DNA play a role in preserving genome stability.
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Affiliation(s)
- Yang Yu
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
| | - Xin Wang
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Jordan Fox
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
| | - Ruofan Yu
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Pilendra Thakre
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
| | - Brenna McCauley
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Nicolas Nikoloutsos
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
- Department of Bioengineering, Rice University, 6500 Main Street, Houston, TX 77030, USA
| | - Qian Li
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
| | - P. J. Hastings
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
| | - Weiwei Dang
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
- Huffington Center on Aging, Baylor College of Medicine, One Baylor Plaza, Houston, TX 77030, USA
| | - Kaifu Chen
- Department of Cardiology, Boston Children’s Hospital, 300 Longwood Avenue, Boston, MA 02115, USA
- Department of Pediatrics, Harvard Medical School, 25 Shattuck Street, Boston, MA 02115, USA
| | - Grzegorz Ira
- Baylor College of Medicine, Department of Molecular and Human Genetics, One Baylor Plaza, Houston, TX 77030, USA
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5
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Yu Y, Wang X, Fox J, Yu R, Thakre P, McCauley B, Nikoloutsos N, Li Q, Hastings PJ, Dang W, Chen K, Ira G. Yeast EndoG prevents genome instability by degrading cytoplasmic DNA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.13.571550. [PMID: 38168242 PMCID: PMC10760121 DOI: 10.1101/2023.12.13.571550] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/05/2024]
Abstract
In metazoans release of mitochondrial DNA or retrotransposon cDNA to cytoplasm can cause sterile inflammation and disease. Cytoplasmic nucleases degrade these DNA species to limit inflammation. It remains unknown whether degradation these DNA also prevents nuclear genome instability. To address this question, we decided to identify the nuclease regulating transfer of these cytoplasmic DNA species to the nucleus. We used an amplicon sequencing-based method in yeast enabling analysis of millions of DSB repair products. Nu clear mt DNA (NUMTs) and retrotransposon cDNA insertions increase dramatically in nondividing stationary phase cells. Yeast EndoG (Nuc1) nuclease limits insertions of cDNA and transfer of very long mtDNA (>10 kb) that forms unstable circles or rarely insert in the genome, but it promotes formation of short NUMTs (∼45-200 bp). Nuc1 also regulates transfer of cytoplasmic DNA to nucleus in aging or during meiosis. We propose that Nuc1 preserves genome stability by degrading retrotransposon cDNA and long mtDNA, while short NUMTs can originate from incompletely degraded mtDNA. This work suggests that nucleases eliminating cytoplasmic DNA play a role in preserving genome stability.
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6
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Tao Y, He C, Lin D, Gu Z, Pu W. Comprehensive Identification of Mitochondrial Pseudogenes (NUMTs) in the Human Telomere-to-Telomere Reference Genome. Genes (Basel) 2023; 14:2092. [PMID: 38003036 PMCID: PMC10671835 DOI: 10.3390/genes14112092] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Revised: 11/09/2023] [Accepted: 11/12/2023] [Indexed: 11/26/2023] Open
Abstract
Practices related to mitochondrial research have long been hindered by the presence of mitochondrial pseudogenes within the nuclear genome (NUMTs). Even though partially assembled human reference genomes like hg38 have included NUMTs compilation, the exhaustive NUMTs within the only complete reference genome (T2T-CHR13) remain unknown. Here, we comprehensively identified the fixed NUMTs within the reference genome using human pan-mitogenome (HPMT) from GeneBank. The inclusion of HPMT serves the purpose of establishing an authentic mitochondrial DNA (mtDNA) mutational spectrum for the identification of NUMTs, distinguishing it from the polymorphic variations found in NUMTs. Using HPMT, we identified approximately 10% of additional NUMTs in three human reference genomes under stricter thresholds. And we also observed an approximate 6% increase in NUMTs in T2T-CHR13 compared to hg38, including NUMTs on the short arms of chromosomes 13, 14, and 15 that were not assembled previously. Furthermore, alignments based on 20-mer from mtDNA suggested the presence of more mtDNA-like short segments within the nuclear genome, which should be avoided for short amplicon or cell free mtDNA detection. Finally, through the assay of transposase-accessible chromatin with high-throughput sequencing (ATAC-seq) on cell lines before and after mtDNA elimination, we concluded that NUMTs have a minimal impact on bulk ATAC-seq, even though 16% of sequencing data originated from mtDNA.
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Affiliation(s)
- Yichen Tao
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai 200438, China; (Y.T.); (D.L.)
| | - Chengpeng He
- Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Nansha District, Guangzhou 511458, China;
| | - Deng Lin
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai 200438, China; (Y.T.); (D.L.)
| | - Zhenglong Gu
- MOE Key Laboratory of Contemporary Anthropology, School of Life Sciences, Fudan University, Shanghai 200438, China; (Y.T.); (D.L.)
- Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Nansha District, Guangzhou 511458, China;
| | - Weilin Pu
- Greater Bay Area Institute of Precision Medicine (Guangzhou), Fudan University, Nansha District, Guangzhou 511458, China;
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Nieto-Panqueva F, Rubalcava-Gracia D, Hamel PP, González-Halphen D. The constraints of allotopic expression. Mitochondrion 2023; 73:30-50. [PMID: 37739243 DOI: 10.1016/j.mito.2023.09.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 08/28/2023] [Accepted: 09/18/2023] [Indexed: 09/24/2023]
Abstract
Allotopic expression is the functional transfer of an organellar gene to the nucleus, followed by synthesis of the gene product in the cytosol and import into the appropriate organellar sub compartment. Here, we focus on mitochondrial genes encoding OXPHOS subunits that were naturally transferred to the nucleus, and critically review experimental evidence that claim their allotopic expression. We emphasize aspects that may have been overlooked before, i.e., when modifying a mitochondrial gene for allotopic expression━besides adapting the codon usage and including sequences encoding mitochondrial targeting signals━three additional constraints should be considered: (i) the average apparent free energy of membrane insertion (μΔGapp) of the transmembrane stretches (TMS) in proteins earmarked for the inner mitochondrial membrane, (ii) the final, functional topology attained by each membrane-bound OXPHOS subunit; and (iii) the defined mechanism by which the protein translocator TIM23 sorts cytosol-synthesized precursors. The mechanistic constraints imposed by TIM23 dictate the operation of two pathways through which alpha-helices in TMS are sorted, that eventually determine the final topology of membrane proteins. We used the biological hydrophobicity scale to assign an average apparent free energy of membrane insertion (μΔGapp) and a "traffic light" color code to all TMS of OXPHOS membrane proteins, thereby predicting which are more likely to be internalized into mitochondria if allotopically produced. We propose that the design of proteins for allotopic expression must make allowance for μΔGapp maximization of highly hydrophobic TMS in polypeptides whose corresponding genes have not been transferred to the nucleus in some organisms.
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Affiliation(s)
- Felipe Nieto-Panqueva
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Diana Rubalcava-Gracia
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico; Division of Molecular Metabolism, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Patrice P Hamel
- Department of Molecular Genetics and Department of Biological Chemistry and Pharmacology, Ohio State University, Columbus, OH, USA; Vellore Institute of Technology (VIT), School of BioScience and Technology, Vellore, Tamil Nadu, India
| | - Diego González-Halphen
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Mexico City, Mexico.
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8
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Emser SV, Spielvogel CP, Millesi E, Steinborn R. Mitochondrial polymorphism m.3017C>T of SHLP6 relates to heterothermy. Front Physiol 2023; 14:1207620. [PMID: 37675281 PMCID: PMC10478271 DOI: 10.3389/fphys.2023.1207620] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 07/31/2023] [Indexed: 09/08/2023] Open
Abstract
Heterothermic thermoregulation requires intricate regulation of metabolic rate and activation of pro-survival factors. Eliciting these responses and coordinating the necessary energy shifts likely involves retrograde signalling by mitochondrial-derived peptides (MDPs). Members of the group were suggested before to play a role in heterothermic physiology, a key component of hibernation and daily torpor. Here we studied the mitochondrial single-nucleotide polymorphism (SNP) m.3017C>T that resides in the evolutionarily conserved gene MT-SHLP6. The substitution occurring in several mammalian orders causes truncation of SHLP6 peptide size from twenty to nine amino acids. Public mass spectrometric (MS) data of human SHLP6 indicated a canonical size of 20 amino acids, but not the use of alternative translation initiation codons that would expand the peptide. The shorter isoform of SHLP6 was found in heterothermic rodents at higher frequency compared to homeothermic rodents (p < 0.001). In heterothermic mammals it was associated with lower minimal body temperature (T b, p < 0.001). In the thirteen-lined ground squirrel, brown adipose tissue-a key organ required for hibernation, showed dynamic changes of the steady-state transcript level of mt-Shlp6. The level was significantly higher before hibernation and during interbout arousal and lower during torpor and after hibernation. Our finding argues to further explore the mode of action of SHLP6 size isoforms with respect to mammalian thermoregulation and possibly mitochondrial retrograde signalling.
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Affiliation(s)
- Sarah V. Emser
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
| | - Clemens P. Spielvogel
- Department of Biomedical Imaging and Image-Guided Therapy, Division of Nuclear Medicine, Medical University of Vienna, Vienna, Austria
| | - Eva Millesi
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Ralf Steinborn
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
- Department of Microbiology, Immunobiology and Genetics, University of Vienna, Vienna, Austria
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Zhou W, Karan KR, Gu W, Klein HU, Sturm G, De Jager PL, Bennett DA, Hirano M, Picard M, Mills RE. Somatic nuclear mitochondrial DNA insertions are prevalent in the human brain and accumulate over time in fibroblasts. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.03.527065. [PMID: 36778249 PMCID: PMC9915708 DOI: 10.1101/2023.02.03.527065] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The transfer of mitochondrial DNA into the nuclear genomes of eukaryotes (Numts) has been linked to lifespan in non-human species 1-3 and recently demonstrated to occur in rare instances from one human generation to the next 4. Here we investigated numtogenesis dynamics in humans in two ways. First, we quantified Numts in 1,187 post-mortem brain and blood samples from different individuals. Compared to circulating immune cells (n=389), post-mitotic brain tissue (n=798) contained more Numts, consistent with their potential somatic accumulation. Within brain samples we observed a 5.5-fold enrichment of somatic Numt insertions in the dorsolateral prefrontal cortex compared to cerebellum samples, suggesting that brain Numts arose spontaneously during development or across the lifespan. Moreover, more brain Numts was linked to earlier mortality. The brains of individuals with no cognitive impairment who died at younger ages carried approximately 2 more Numts per decade of life lost than those who lived longer. Second, we tested the dynamic transfer of Numts using a repeated-measures WGS design in a human fibroblast model that recapitulates several molecular hallmarks of aging 5. These longitudinal experiments revealed a gradual accumulation of one Numt every ~13 days. Numtogenesis was independent of large-scale genomic instability and unlikely driven cell clonality. Targeted pharmacological perturbations including chronic glucocorticoid signaling or impairing mitochondrial oxidative phosphorylation (OxPhos) only modestly increased the rate of numtogenesis, whereas patient-derived SURF1-mutant cells exhibiting mtDNA instability accumulated Numts 4.7-fold faster than healthy donors. Combined, our data document spontaneous numtogenesis in human cells and demonstrate an association between brain cortical somatic Numts and human lifespan. These findings open the possibility that mito-nuclear horizontal gene transfer among human post-mitotic tissues produce functionally-relevant human Numts over timescales shorter than previously assumed.
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Affiliation(s)
- Weichen Zhou
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Kalpita R. Karan
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, USA
| | - Wenjin Gu
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
| | - Hans-Ulrich Klein
- Center for Translational & Computational Neuroimmunology, Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032 USA
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY 10032 USA
| | - Gabriel Sturm
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, USA
- Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Philip L. De Jager
- Center for Translational & Computational Neuroimmunology, Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032 USA
- Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, Columbia University Irving Medical Center, New York, NY 10032 USA
| | - David A. Bennett
- Rush Alzheimer’s Disease Center, Rush University Medical Center, Chicago, IL 60612 USA
| | - Michio Hirano
- Center for Translational & Computational Neuroimmunology, Department of Neurology, Columbia University Irving Medical Center, New York, NY 10032 USA
| | - Martin Picard
- Department of Psychiatry, Division of Behavioral Medicine, Columbia University Irving Medical Center, New York, USA
- Department of Neurology, H. Houston Merritt Center, Columbia University Translational Neuroscience Initiative, Columbia University Irving Medical Center, New York, USA
- New York State Psychiatric Institute, New York, USA
| | - Ryan E Mills
- Department of Computational Medicine and Bioinformatics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, MI 48109, USA
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Abstract
This review paper covers the forensic-relevant literature in biological sciences from 2019 to 2022 as a part of the 20th INTERPOL International Forensic Science Managers Symposium. Topics reviewed include rapid DNA testing, using law enforcement DNA databases plus investigative genetic genealogy DNA databases along with privacy/ethical issues, forensic biology and body fluid identification, DNA extraction and typing methods, mixture interpretation involving probabilistic genotyping software (PGS), DNA transfer and activity-level evaluations, next-generation sequencing (NGS), DNA phenotyping, lineage markers (Y-chromosome, mitochondrial DNA, X-chromosome), new markers and approaches (microhaplotypes, proteomics, and microbial DNA), kinship analysis and human identification with disaster victim identification (DVI), and non-human DNA testing including wildlife forensics. Available books and review articles are summarized as well as 70 guidance documents to assist in quality control that were published in the past three years by various groups within the United States and around the world.
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Post hoc deconvolution of human mitochondrial DNA mixtures by EMMA 2 using fine-tuned Phylotree nomenclature. Comput Struct Biotechnol J 2022; 20:3630-3638. [PMID: 35860401 PMCID: PMC9283771 DOI: 10.1016/j.csbj.2022.06.053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2022] [Revised: 06/24/2022] [Accepted: 06/25/2022] [Indexed: 11/23/2022] Open
Abstract
MtDNA mixtures are observed frequently and difficult to deconvolute. Most previous methods require raw data or quantitative information. EMMA 2 produces valid splittings from consensus sequences of any sequencing technology. EMMA 2 can deconvolute 2 and 3 person mixtures in a fast and traceable way.
In this paper we present a new algorithm for splitting (partial) human mitogenomes into components with high similarity to haplogroup motifs of Phylotree. The algorithm reads a (partial) mitogenome coded by the differences to the reference (rCRS) and outputs the estimated haplogroups of the putative components. The algorithm requires no special information on the raw data of the sequencing process and is therefore suited for the post hoc analysis of mixtures of any sequencing technology. The software EMMA 2 implementing the algorithm will be made available via the EMPOP (https://empop.online) database and extends the nine years old software EMMA for haplogrouping single mitogenomes to mixtures with at most three components.
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Parakatselaki ME, Zhu CT, Rand D, Ladoukakis ED. NUMTs Can Imitate Biparental Transmission of mtDNA-A Case in Drosophila melanogaster. Genes (Basel) 2022; 13:genes13061023. [PMID: 35741785 PMCID: PMC9222939 DOI: 10.3390/genes13061023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2022] [Revised: 05/27/2022] [Accepted: 06/02/2022] [Indexed: 11/16/2022] Open
Abstract
mtDNA sequences can be incorporated into the nuclear genome and produce nuclear mitochondrial fragments (NUMTs), which resemble mtDNA in their sequence but are transmitted biparentally, like the nuclear genome. NUMTs can be mistaken as real mtDNA and may lead to the erroneous impression that mtDNA is biparentally transmitted. Here, we report a case of mtDNA heteroplasmy in a Drosophila melanogaster DGRP line, in which the one haplotype was biparentally transmitted in an autosomal manner. Given the sequence identity of this haplotype with the mtDNA, the crossing experiments led to uncertainty about whether heteroplasmy was real or an artifact due to a NUMT. More specific experiments revealed that there is a large NUMT insertion in the X chromosome of a specific DGRP line, imitating biparental inheritance of mtDNA. Our result suggests that studies on mtDNA heteroplasmy and on mtDNA inheritance should first exclude the possibility of NUMT interference in their data.
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Affiliation(s)
| | - Chen-Tseh Zhu
- Department of Ecology, Evolutionary and Organismal Biology, Brown University, Providence, RI 02912, USA; (C.-T.Z.); (D.R.)
| | - David Rand
- Department of Ecology, Evolutionary and Organismal Biology, Brown University, Providence, RI 02912, USA; (C.-T.Z.); (D.R.)
| | - Emmanuel D. Ladoukakis
- Department of Biology, University of Crete, Voutes University Campus, 70013 Iraklio, Greece;
- Correspondence: ; Tel.: +30-281-039-4067
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Battle SL, Puiu D, Verlouw J, Broer L, Boerwinkle E, Taylor KD, Rotter JI, Rich SS, Grove ML, Pankratz N, Fetterman JL, Liu C, Arking D. A bioinformatics pipeline for estimating mitochondrial DNA copy number and heteroplasmy levels from whole genome sequencing data. NAR Genom Bioinform 2022; 4:lqac034. [PMID: 35591888 PMCID: PMC9112767 DOI: 10.1093/nargab/lqac034] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Revised: 03/16/2022] [Accepted: 04/25/2022] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial diseases are a heterogeneous group of disorders that can be caused by mutations in the nuclear or mitochondrial genome. Mitochondrial DNA (mtDNA) variants may exist in a state of heteroplasmy, where a percentage of DNA molecules harbor a variant, or homoplasmy, where all DNA molecules have the same variant. The relative quantity of mtDNA in a cell, or copy number (mtDNA-CN), is associated with mitochondrial function, human disease, and mortality. To facilitate accurate identification of heteroplasmy and quantify mtDNA-CN, we built a bioinformatics pipeline that takes whole genome sequencing data and outputs mitochondrial variants, and mtDNA-CN. We incorporate variant annotations to facilitate determination of variant significance. Our pipeline yields uniform coverage by remapping to a circularized chrM and by recovering reads falsely mapped to nuclear-encoded mitochondrial sequences. Notably, we construct a consensus chrM sequence for each sample and recall heteroplasmy against the sample's unique mitochondrial genome. We observe an approximately 3-fold increased association with age for heteroplasmic variants in non-homopolymer regions and, are better able to capture genetic variation in the D-loop of chrM compared to existing software. Our bioinformatics pipeline more accurately captures features of mitochondrial genetics than existing pipelines that are important in understanding how mitochondrial dysfunction contributes to disease.
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Affiliation(s)
- Stephanie L Battle
- McKusick-Nathans Institute, Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Daniela Puiu
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | | | - Joost Verlouw
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Linda Broer
- Department of Internal Medicine, Erasmus Medical Center, Rotterdam, The Netherlands
| | - Eric Boerwinkle
- Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX, USA
- Human Genome Sequencing Center, Baylor College of Medicine, Houston, TX, USA
| | - Kent D Taylor
- The Institute for Translational Genomics and Population Sciences, Department of Pediatrics, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Jerome I Rotter
- The Institute for Translational Genomics and Population Sciences, Department of Pediatrics, The Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Stephan S Rich
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA, USA
| | - Megan L Grove
- Human Genetics Center, Department of Epidemiology, Human Genetics, and Environmental Sciences, School of Public Health, The University of Texas Health Science Center at Houston, Houston, TX, USA
| | - Nathan Pankratz
- Department of Laboratory Medicine and Pathology, University of Minnesota, Minneapolis, MN, USA
| | - Jessica L Fetterman
- Evans Department of Medicine and the Whitaker Cardiovascular Institute, Boston University School of Medicine, Boston, MA, USA
| | - Chunyu Liu
- Framingham Heart Study, Boston University School of Medicine, Boston, MA, USA
- Department of Biostatistics, Boston University School of Public Health, Boston, MA, USA
| | - Dan E Arking
- McKusick-Nathans Institute, Department of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
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14
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Huang Q, Wu D, Zhao J, Yan Z, Chen L, Guo S, Wang D, Yuan C, Wang Y, Liu X, Xing J. TFAM loss induces nuclear actin assembly upon mDia2 malonylation to promote liver cancer metastasis. EMBO J 2022; 41:e110324. [PMID: 35451091 PMCID: PMC9156967 DOI: 10.15252/embj.2021110324] [Citation(s) in RCA: 21] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2021] [Revised: 03/30/2022] [Accepted: 04/01/2022] [Indexed: 11/09/2022] Open
Abstract
The mechanisms underlying cancer metastasis remain poorly understood. Here, we report that TFAM deficiency rapidly and stably induced spontaneous lung metastasis in mice with liver cancer. Interestingly, unexpected polymerization of nuclear actin was observed in TFAM-knockdown HCC cells when cytoskeleton was examined. Polymerization of nuclear actin is causally linked to the high-metastatic ability of HCC cells by modulating chromatin accessibility and coordinating the expression of genes associated with extracellular matrix remodeling, angiogenesis, and cell migration. Mechanistically, TFAM deficiency blocked the TCA cycle and increased the intracellular malonyl-CoA levels. Malonylation of mDia2, which drives actin assembly, promotes its nuclear translocation. Importantly, inhibition of malonyl-CoA production or nuclear actin polymerization significantly impeded the spread of HCC cells in mice. Moreover, TFAM was significantly downregulated in metastatic HCC tissues and was associated with overall survival and time to tumor recurrence of HCC patients. Taken together, our study connects mitochondria to the metastasis of human cancer via uncovered mitochondria-to-nucleus retrograde signaling, indicating that TFAM may serve as an effective target to block HCC metastasis.
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Affiliation(s)
- Qichao Huang
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Dan Wu
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Jing Zhao
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Zeyu Yan
- Department of General Surgery, Tangdu Hospital, Fourth Military Medical University, Xi'an, China
| | - Lin Chen
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Shanshan Guo
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Dalin Wang
- Department of Hepatobiliary Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Chong Yuan
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Yinping Wang
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Xiaoli Liu
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
| | - Jinliang Xing
- State Key Laboratory of Cancer Biology and Department of Physiology and Pathophysiology, Fourth Military Medical University, Xi'an, China
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15
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Fields PD, Waneka G, Naish M, Schatz MC, Henderson IR, Sloan DB. Complete sequence of a 641-kb insertion of mitochondrial DNA in the Arabidopsis thaliana nuclear genome. Genome Biol Evol 2022; 14:6572048. [PMID: 35446419 PMCID: PMC9071559 DOI: 10.1093/gbe/evac059] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2022] [Indexed: 11/14/2022] Open
Abstract
Intracellular transfers of mitochondrial DNA continue to shape nuclear genomes. Chromosome 2 of the model plant Arabidopsis thaliana contains one of the largest known nuclear insertions of mitochondrial DNA (numts). Estimated at over 600 kb in size, this numt is larger than the entire Arabidopsis mitochondrial genome. The primary Arabidopsis nuclear reference genome contains less than half of the numt because of its structural complexity and repetitiveness. Recent data sets generated with improved long-read sequencing technologies (PacBio HiFi) provide an opportunity to finally determine the accurate sequence and structure of this numt. We performed a de novo assembly using sequencing data from recent initiatives to span the Arabidopsis centromeres, producing a gap-free sequence of the Chromosome 2 numt, which is 641 kb in length and has 99.933% nucleotide sequence identity with the actual mitochondrial genome. The numt assembly is consistent with the repetitive structure previously predicted from fiber-based fluorescent in situ hybridization. Nanopore sequencing data indicate that the numt has high levels of cytosine methylation, helping to explain its biased spectrum of nucleotide sequence divergence and supporting previous inferences that it is transcriptionally inactive. The original numt insertion appears to have involved multiple mitochondrial DNA copies with alternative structures that subsequently underwent an additional duplication event within the nuclear genome. This work provides insights into numt evolution, addresses one of the last unresolved regions of the Arabidopsis reference genome, and represents a resource for distinguishing between highly similar numt and mitochondrial sequences in studies of transcription, epigenetic modifications, and de novo mutations.
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Affiliation(s)
- Peter D Fields
- Department of Biology, Colorado State University, Fort Collins, CO, USA.,Department of Environmental Sciences, Zoology, University of Basel, Basel, Switzerland
| | - Gus Waneka
- Department of Biology, Colorado State University, Fort Collins, CO, USA
| | - Matthew Naish
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Michael C Schatz
- Department of Computer Science, Johns Hopkins University, Baltimore, MD, USA
| | - Ian R Henderson
- Department of Plant Sciences, University of Cambridge, Cambridge, UK
| | - Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO, USA
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16
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Ip EKK, Troup M, Xu C, Winlaw DS, Dunwoodie SL, Giannoulatou E. Benchmarking the Effectiveness and Accuracy of Multiple Mitochondrial DNA Variant Callers: Practical Implications for Clinical Application. Front Genet 2022; 13:692257. [PMID: 35350246 PMCID: PMC8957813 DOI: 10.3389/fgene.2022.692257] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2021] [Accepted: 01/27/2022] [Indexed: 12/30/2022] Open
Abstract
Mitochondrial DNA (mtDNA) mutations contribute to human disease across a range of severity, from rare, highly penetrant mutations causal for monogenic disorders to mutations with milder contributions to phenotypes. mtDNA variation can exist in all copies of mtDNA or in a percentage of mtDNA copies and can be detected with levels as low as 1%. The large number of copies of mtDNA and the possibility of multiple alternative alleles at the same DNA nucleotide position make the task of identifying allelic variation in mtDNA very challenging. In recent years, specialized variant calling algorithms have been developed that are tailored to identify mtDNA variation from whole-genome sequencing (WGS) data. However, very few studies have systematically evaluated and compared these methods for the detection of both homoplasmy and heteroplasmy. A publicly available synthetic gold standard dataset was used to assess four mtDNA variant callers (Mutserve, mitoCaller, MitoSeek, and MToolBox), and the commonly used Genome Analysis Toolkit “best practices” pipeline, which is included in most current WGS pipelines. We also used WGS data from 126 trios and calculated the percentage of maternally inherited variants as a metric of calling accuracy, especially for homoplasmic variants. We additionally compared multiple pathogenicity prediction resources for mtDNA variants. Although the accuracy of homoplasmic variant detection was high for the majority of the callers with high concordance across callers, we found a very low concordance rate between mtDNA variant callers for heteroplasmic variants ranging from 2.8% to 3.6%, for heteroplasmy thresholds of 5% and 1%. Overall, Mutserve showed the best performance using the synthetic benchmark dataset. The analysis of mtDNA pathogenicity resources also showed low concordance in prediction results. We have shown that while homoplasmic variant calling is consistent between callers, there remains a significant discrepancy in heteroplasmic variant calling. We found that resources like population frequency databases and pathogenicity predictors are now available for variant annotation but still need refinement and improvement. With its peculiarities, the mitochondria require special considerations, and we advocate that caution needs to be taken when analyzing mtDNA data from WGS data.
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Affiliation(s)
- Eddie K K Ip
- Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.,St. Vincent's Clinical School, Sydney, NSW, Australia
| | - Michael Troup
- Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
| | - Colin Xu
- School of Computer Science and Engineering, Sydney, NSW, Australia
| | - David S Winlaw
- Cardiothoracic Surgery, Cincinnati Children's Hospital Medical Centre, Heart Institute, Cincinnati, OH, United States
| | - Sally L Dunwoodie
- Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.,St. Vincent's Clinical School, Sydney, NSW, Australia
| | - Eleni Giannoulatou
- Victor Chang Cardiac Research Institute, Sydney, NSW, Australia.,St. Vincent's Clinical School, Sydney, NSW, Australia
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17
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Sturk-Andreaggi K, Ring JD, Ameur A, Gyllensten U, Bodner M, Parson W, Marshall C, Allen M. The Value of Whole-Genome Sequencing for Mitochondrial DNA Population Studies: Strategies and Criteria for Extracting High-Quality Mitogenome Haplotypes. Int J Mol Sci 2022; 23:ijms23042244. [PMID: 35216360 PMCID: PMC8876724 DOI: 10.3390/ijms23042244] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 02/08/2022] [Accepted: 02/09/2022] [Indexed: 02/04/2023] Open
Abstract
Whole-genome sequencing (WGS) data present a readily available resource for mitochondrial genome (mitogenome) haplotypes that can be utilized for genetics research including population studies. However, the reconstruction of the mitogenome is complicated by nuclear mitochondrial DNA (mtDNA) segments (NUMTs) that co-align with the mtDNA sequences and mimic authentic heteroplasmy. Two minimum variant detection thresholds, 5% and 10%, were assessed for the ability to produce authentic mitogenome haplotypes from a previously generated WGS dataset. Variants associated with NUMTs were detected in the mtDNA alignments for 91 of 917 (~8%) Swedish samples when the 5% frequency threshold was applied. The 413 observed NUMT variants were predominantly detected in two regions (nps 12,612–13,105 and 16,390–16,527), which were consistent with previously documented NUMTs. The number of NUMT variants was reduced by ~97% (400) using a 10% frequency threshold. Furthermore, the 5% frequency data were inconsistent with a platinum-quality mitogenome dataset with respect to observed heteroplasmy. These analyses illustrate that a 10% variant detection threshold may be necessary to ensure the generation of reliable mitogenome haplotypes from WGS data resources.
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Affiliation(s)
- Kimberly Sturk-Andreaggi
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
- Correspondence: (K.S.-A.); (M.A.)
| | - Joseph D. Ring
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
| | - Adam Ameur
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
| | - Ulf Gyllensten
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
| | - Martin Bodner
- Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria; (M.B.); (W.P.)
| | - Walther Parson
- Institute of Legal Medicine, Medical University of Innsbruck, Innsbruck 6020, Austria; (M.B.); (W.P.)
- Forensic Science Program, The Pennsylvania State University, University Park, PA 16801, USA
| | - Charla Marshall
- Armed Forces Medical Examiner System’s Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, Dover, DE 19902, USA; (J.D.R.); (C.M.)
- SNA International, LLC, Alexandria, VA 22314, USA
- Forensic Science Program, The Pennsylvania State University, University Park, PA 16801, USA
| | - Marie Allen
- Department of Immunology Genetics and Pathology, Uppsala University, Uppsala 751 08, Sweden; (A.A.); (U.G.)
- Correspondence: (K.S.-A.); (M.A.)
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18
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Laricchia KM, Lake NJ, Watts NA, Shand M, Haessly A, Gauthier L, Benjamin D, Banks E, Soto J, Garimella K, Emery J, Rehm HL, MacArthur DG, Tiao G, Lek MV, Mootha VK, Calvo SE. Mitochondrial DNA variation across 56,434 individuals in gnomAD. Genome Res 2022; 32:569-582. [PMID: 35074858 PMCID: PMC8896463 DOI: 10.1101/gr.276013.121] [Citation(s) in RCA: 27] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Accepted: 01/19/2022] [Indexed: 11/25/2022]
Abstract
Genomic databases of allele frequency are extremely helpful for evaluating clinical variants of unknown significance; however, until now, databases such as the Genome Aggregation Database (gnomAD) have focused on nuclear DNA and have ignored the mitochondrial genome (mtDNA). Here we present a pipeline to call mtDNA variants that addresses three technical challenges: (i) detecting homoplasmic and heteroplasmic variants, present respectively in all or a fraction of mtDNA molecules, (ii) circular mtDNA genome, and (iii) misalignment of nuclear sequences of mitochondrial origin (NUMTs). We observed that mtDNA copy number per cell varied across gnomAD cohorts and influenced the fraction of NUMT-derived false-positive variant calls, which can account for the majority of putative heteroplasmies. To avoid false positives, we excluded contaminated samples, cell lines, and samples prone to NUMT misalignment due to few mtDNA copies. Furthermore, we report variants with heteroplasmy greater than 10%. We applied this pipeline to 56,434 whole genome sequences in the gnomAD v3.1 database that includes individuals of European (58%), African (25%), Latino (10%), and Asian (5%) ancestry. Our gnomAD v3.1 release contains population frequencies for 10,850 unique mtDNA variants at more than half of all mtDNA bases. We report frequencies within each nuclear ancestral population and mitochondrial haplogroup. Homoplasmic variants account for most variant calls (98%) and unique variants (85%). We observed that 1/250 individuals carry a pathogenic mtDNA variant with heteroplasmy above 10%. These mtDNA population allele frequencies are freely accessible and will aid in diagnostic interpretation and research studies.
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19
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Singh I, Parte P. Heterogeneity in the Epigenetic Landscape of Murine Testis-Specific Histone Variants TH2A and TH2B Sharing the Same Bi-Directional Promoter. Front Cell Dev Biol 2021; 9:755751. [PMID: 34938732 PMCID: PMC8685415 DOI: 10.3389/fcell.2021.755751] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2021] [Accepted: 10/25/2021] [Indexed: 01/15/2023] Open
Abstract
Testis-specific histone variants are crucial to promote open chromatin structure to enable nucleosome disassembly in the final stages of spermiogenesis. However, even after histone replacement, mature sperm retain a proportion of these variants, the function of which is unknown. The present study aimed to understand the functional relevance of the retained H2B and H2A variants, TH2B and TH2A. While no literature is available on the phenotype of TH2A knockouts, TH2B/TH2A double knockout male mice are reported to be infertile. In this study, ChIP-seq analysis was done for TH2B and TH2A to understand the epigenomics of the retained TH2B and TH2A, using murine caudal sperm. Distribution across genomic partitions revealed ∼35% of the TH2B peaks within ±5 kb of TSS whereas TH2A peaks distribution was sparse at TSS. Gene Ontology revealed embryo development as the most significant term associated with TH2B. Also, based on genomic regions, TH2B was observed to be associated with spindle assembly and various meiosis-specific genes, which is an important finding as TH2A/TH2B DKO mice have been reported to have defective cohesin release. A comparison of mouse and human TH2B-linked chromatin revealed 26% overlap between murine and human TH2B-associated genes. This overlap included genes crucial for embryogenesis. Most importantly, heterogeneity in the epigenetic landscape of TH2A and TH2B was seen, which is intriguing as TH2B and TH2A are well reported to be present in the same nucleosomes to promote open chromatin. Additionally, unlike TH2B, TH2A was enriched on the mitochondrial chromosome. TH2A was found to be associated with Nuclear insertion of Mitochondrial DNA sequences (NUMTs) in sperm. A comprehensive analysis of these observations indicates novel functions for the sperm-retained TH2B and TH2A.
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Affiliation(s)
- Isha Singh
- Department of Gamete Immunobiology, ICMR-National Institute for Research in Reproductive Health, Mumbai, India
| | - Priyanka Parte
- Department of Gamete Immunobiology, ICMR-National Institute for Research in Reproductive Health, Mumbai, India
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20
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Emser SV, Schaschl H, Millesi E, Steinborn R. Extension of Mitogenome Enrichment Based on Single Long-Range PCR: mtDNAs and Putative Mitochondrial-Derived Peptides of Five Rodent Hibernators. Front Genet 2021; 12:685806. [PMID: 35027919 PMCID: PMC8749263 DOI: 10.3389/fgene.2021.685806] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Accepted: 11/10/2021] [Indexed: 12/14/2022] Open
Abstract
Enriching mitochondrial DNA (mtDNA) for sequencing entire mitochondrial genomes (mitogenomes) can be achieved by single long-range PCR. This avoids interference from the omnipresent nuclear mtDNA sequences (NUMTs). The approach is currently restricted to the use of samples collected from humans and ray-finned fishes. Here, we extended the use of single long-range PCR by introducing back-to-back oligonucleotides that target a sequence of extraordinary homology across vertebrates. The assay was applied to five hibernating rodents, namely alpine marmot, Arctic and European ground squirrels, and common and garden dormice, four of which have not been fully sequenced before. Analysis of the novel mitogenomes focussed on the prediction of mitochondrial-derived peptides (MDPs) providing another level of information encoded by mtDNA. The comparison of MOTS-c, SHLP4 and SHLP6 sequences across vertebrate species identified segments of high homology that argue for future experimentation. In addition, we evaluated four candidate polymorphisms replacing an amino acid in mitochondrially encoded subunits of the oxidative phosphorylation (OXPHOS) system that were reported in relation to cold-adaptation. No obvious pattern was found for the diverse sets of mammalian species that either apply daily or multiday torpor or otherwise cope with cold. In summary, our single long-range PCR assay applying a pair of back-to-back primers that target a consensus sequence motif of Vertebrata has potential to amplify (intact) mitochondrial rings present in templates from a taxonomically diverse range of vertebrates. It could be promising for studying novel mitogenomes, mitotypes of a population and mitochondrial heteroplasmy in a sensitive, straightforward and flexible manner.
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Affiliation(s)
- Sarah V. Emser
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Helmut Schaschl
- Department of Evolutionary Anthropology, University of Vienna, Vienna, Austria
| | - Eva Millesi
- Department of Behavioral and Cognitive Biology, University of Vienna, Vienna, Austria
| | - Ralf Steinborn
- Genomics Core Facility, VetCore, University of Veterinary Medicine, Vienna, Austria
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21
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Mitochondrial DNA in forensic use. Emerg Top Life Sci 2021; 5:415-426. [PMID: 34374411 PMCID: PMC8457767 DOI: 10.1042/etls20210204] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 06/27/2021] [Accepted: 07/22/2021] [Indexed: 01/02/2023]
Abstract
Genetic analysis of mitochondrial DNA (mtDNA) has always been a useful tool for forensic geneticists, mainly because of its ubiquitous presence in biological material, even in the absence of nuclear DNA. Sequencing, however, is not a skill that is part of the routine forensic analysis because of the relative rarity of requests, and the need for retention of necessary skill sets and associated accreditation issues. While standard Sanger sequencing may be relatively simple, many requests are made in the face of compromised biological samples. Newer technologies, provided through massively parallel sequencing (MPS), will increase the opportunity for scientists to include this tool in their routine, particularly for missing person investigations. MPS has also enabled a different approach to sequencing that can increase sensitivity in a more targeted approach. In these circumstances it is likely that only a laboratory that specialises in undertaking forensic mtDNA analysis will be able to take these difficult cases forward, more so because reviews of the literature have revealed significantly high levels of typing errors in publications reporting mtDNA sequences. The forensic community has set out important guidelines, not only in the practical aspects of analysis, but also in the interpretation of that sequence to ensure that accurate comparisons can be made. Analysis of low-level, compromised and ancient DNA is not easy, however, as contamination is extremely difficult to eliminate and circumstances leading to sequencing errors are all too easily introduced. These problems, and solutions, are discussed in the article in relation to several historic cases.
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22
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Pagnamenta AT, Wei W, Rahman S, Chinnery PF. Biparental inheritance of mitochondrial DNA revisited. Nat Rev Genet 2021; 22:477-478. [PMID: 34031572 DOI: 10.1038/s41576-021-00380-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Alistair T Pagnamenta
- Wellcome Centre for Human Genetics and the NIHR Oxford Biomedical Research Centre, University of Oxford, Oxford, UK
| | - Wei Wei
- Department of Clinical Neurosciences and the MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK
| | - Shamima Rahman
- UCL Great Ormond Street Institute of Child Health, London, UK
| | - Patrick F Chinnery
- Department of Clinical Neurosciences and the MRC Mitochondrial Biology Unit, University of Cambridge, Cambridge Biomedical Campus, Cambridge, UK.
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23
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mtDNA Heteroplasmy: Origin, Detection, Significance, and Evolutionary Consequences. Life (Basel) 2021; 11:life11070633. [PMID: 34209862 PMCID: PMC8307225 DOI: 10.3390/life11070633] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2021] [Accepted: 06/24/2021] [Indexed: 12/11/2022] Open
Abstract
Mitochondrial DNA (mtDNA) is predominately uniparentally transmitted. This results in organisms with a single type of mtDNA (homoplasmy), but two or more mtDNA haplotypes have been observed in low frequency in several species (heteroplasmy). In this review, we aim to highlight several aspects of heteroplasmy regarding its origin and its significance on mtDNA function and evolution, which has been progressively recognized in the last several years. Heteroplasmic organisms commonly occur through somatic mutations during an individual’s lifetime. They also occur due to leakage of paternal mtDNA, which rarely happens during fertilization. Alternatively, heteroplasmy can be potentially inherited maternally if an egg is already heteroplasmic. Recent advances in sequencing techniques have increased the ability to detect and quantify heteroplasmy and have revealed that mitochondrial DNA copies in the nucleus (NUMTs) can imitate true heteroplasmy. Heteroplasmy can have significant evolutionary consequences on the survival of mtDNA from the accumulation of deleterious mutations and for its coevolution with the nuclear genome. Particularly in humans, heteroplasmy plays an important role in the emergence of mitochondrial diseases and determines the success of the mitochondrial replacement therapy, a recent method that has been developed to cure mitochondrial diseases.
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24
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Hofreiter M, Sneberger J, Pospisek M, Vanek D. Progress in forensic bone DNA analysis: Lessons learned from ancient DNA. Forensic Sci Int Genet 2021; 54:102538. [PMID: 34265517 DOI: 10.1016/j.fsigen.2021.102538] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Revised: 03/07/2021] [Accepted: 05/25/2021] [Indexed: 01/18/2023]
Abstract
Research on ancient and forensic DNA is related in many ways, and the two fields must deal with similar obstacles. Therefore, communication between these two communities has the potential to improve results in both research fields. Here, we present the insights gained in the ancient DNA community with regard to analyzing DNA from aged skeletal material and the potential use of the developed protocols in forensic work. We discuss the various steps, from choosing samples for DNA extraction to deciding between classical PCR amplification and massively parallel sequencing approaches. Based on the progress made in ancient DNA analyses combined with the requirements of forensic work, we suggest that there is substantial potential for incorporating ancient DNA approaches into forensic protocols, a process that has already begun to a considerable extent. However, taking full advantage of the experiences gained from ancient DNA work will require comparative studies by the forensic DNA community to tailor the methods developed for ancient samples to the specific needs of forensic studies and case work. If successful, in our view, the benefits for both communities would be considerable.
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Affiliation(s)
- Michael Hofreiter
- Institute for Biochemistry and Biology, University of Potsdam, Karl-Liebknecht-Str. 24-25, 14476 Potsdam, Germany.
| | - Jiri Sneberger
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, Prague 2 12843, Czech Republic; Department of the History of the Middle Ages of Museum of West Bohemia, Kopeckeho sady 2, Pilsen 30100, Czech Republic; Nuclear Physics Institute of the CAS, Na Truhlarce 39/64, Prague 18086, Czech Republic
| | - Martin Pospisek
- Department of Genetics and Microbiology, Faculty of Science, Charles University in Prague, Vinicna 5, Prague 2 12843, Czech Republic; Biologicals s.r.o., Sramkova 315, Ricany 25101, Czech Republic
| | - Daniel Vanek
- Forensic DNA Service, Janovskeho 18, Prague 7 17000, Czech Republic; Institute of Legal Medicine, Bulovka Hospital, Prague, Czech Republic; Charles University in Prague, 2nd Faculty of Medicine, Prague, Czech Republic.
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Marshall C, Parson W. Interpreting NUMTs in forensic genetics: Seeing the forest for the trees. Forensic Sci Int Genet 2021; 53:102497. [PMID: 33740708 DOI: 10.1016/j.fsigen.2021.102497] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 03/10/2021] [Accepted: 03/11/2021] [Indexed: 01/29/2023]
Abstract
Nuclear mitochondrial DNA (mtDNA) segments (NUMTs) were discovered shortly after sequencing the first human mitochondrial genome. They have earlier been considered to represent archaic elements of ancient insertion events, but modern sequencing technologies and growing databases of mtDNA and NUMT sequences confirm that they are abundant and some of them phylogenetically young. Here, we build upon mtDNA/NUMT review articles published in the mid 2010 s and focus on the distinction of NUMTs and other artefacts that can be observed in aligned sequence reads, such as mixtures (contamination), point heteroplasmy, sequencing error and cytosine deamination. We show practical examples of the effect of the mtDNA enrichment method on the representation of NUMTs in the mapped sequence data and discuss methods to bioinformatically filter NUMTs from mtDNA reads.
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Affiliation(s)
- Charla Marshall
- Armed Forces Medical Examiner System's Armed Forces DNA Identification Laboratory (AFMES-AFDIL), Dover Air Force Base, DE 19902, USA; SNA International, Contractor Supporting the AFMES-AFDIL, Alexandria, VA 22314, USA; Forensic Science Program, The Pennsylvania State University, University Park, PA 16802, USA
| | - Walther Parson
- Forensic Science Program, The Pennsylvania State University, University Park, PA 16802, USA; Institute of Legal Medicine, Medical University of Innsbruck, 6020 Innsbruck, Austria.
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26
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Liehr T. Repetitive Elements in Humans. Int J Mol Sci 2021; 22:ijms22042072. [PMID: 33669810 PMCID: PMC7922087 DOI: 10.3390/ijms22042072] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Revised: 02/05/2021] [Accepted: 02/15/2021] [Indexed: 12/21/2022] Open
Abstract
Repetitive DNA in humans is still widely considered to be meaningless, and variations within this part of the genome are generally considered to be harmless to the carrier. In contrast, for euchromatic variation, one becomes more careful in classifying inter-individual differences as meaningless and rather tends to see them as possible influencers of the so-called 'genetic background', being able to at least potentially influence disease susceptibilities. Here, the known 'bad boys' among repetitive DNAs are reviewed. Variable numbers of tandem repeats (VNTRs = micro- and minisatellites), small-scale repetitive elements (SSREs) and even chromosomal heteromorphisms (CHs) may therefore have direct or indirect influences on human diseases and susceptibilities. Summarizing this specific aspect here for the first time should contribute to stimulating more research on human repetitive DNA. It should also become clear that these kinds of studies must be done at all available levels of resolution, i.e., from the base pair to chromosomal level and, importantly, the epigenetic level, as well.
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Affiliation(s)
- Thomas Liehr
- Institute of Human Genetics, Jena University Hospital, Friedrich Schiller University, Am Klinikum 1, D-07747 Jena, Germany
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