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Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. Proc Natl Acad Sci U S A 2024; 121:e2321267121. [PMID: 38838014 PMCID: PMC11181141 DOI: 10.1073/pnas.2321267121] [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: 12/09/2023] [Accepted: 05/13/2024] [Indexed: 06/07/2024] Open
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here, we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Results revealed pervasive sex differences in mitochondrial effects, including effects on energetics and aging involving nuclear interactions throughout the genome. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, and nuclear effects on mitochondrial expression. While based on a small set of crosses, sex-specific increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
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Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Ben A. Flanagan
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
| | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, Los Angeles, CA90089
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2
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Moorthy R, Bhattamisra SK, Pandey M, Mayuren J, Kow CS, Candasamy M. Mitochondria and diabetes: insights and potential therapies. Expert Rev Endocrinol Metab 2024; 19:141-154. [PMID: 38347803 DOI: 10.1080/17446651.2024.2307526] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/16/2023] [Accepted: 01/16/2024] [Indexed: 02/29/2024]
Abstract
INTRODUCTION Type 2 diabetes (T2D) presents significant global health and economic challenges, contributing to complications such as stroke, cardiovascular disease, kidney dysfunction, and cancer. The current review explores the crucial role of mitochondria, essential for fuel metabolism, in diabetes-related processes. AREAS COVERED Mitochondrial deficits impact insulin-resistant skeletal muscles, adipose tissue, liver, and pancreatic β-cells, affecting glucose and lipid balance. Exercise emerges as a key factor in enhancing mitochondrial function, thereby reducing insulin resistance. Additionally, the therapeutic potential of mitochondrial uncoupling, which generates heat instead of ATP, is discussed. We explore the intricate link between mitochondrial function and diabetes, investigating genetic interventions to mitigate diabetes-related complications. We also cover the impact of insulin deficiency on mitochondrial function, the role of exercise in addressing mitochondrial defects in insulin resistance, and the potential of mitochondrial uncoupling. Furthermore, a comprehensive analysis of Mitochondrial Replacement Therapies (MRT) techniques is presented. EXPERT OPINION MRTs hold promise in preventing the transmission of mitochondrial disease. However, addressing ethical, regulatory, and technical considerations is crucial. Integrating mitochondrial-based treatments requires a careful balance between innovation and safety. Ethical dimensions and regulatory aspects of MRT are examined, emphasizing collaborative efforts for the responsible advancement of human health.
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Affiliation(s)
- Renupiriya Moorthy
- School of Health Sciences, International Medical University, Kuala Lumpur, Malaysia
| | - Subrat Kumar Bhattamisra
- Department of Life Sciences, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
- Department of Pharmacology, GITAM School of Pharmacy, Gandhi Institute of Technology and Management (GITAM Deemed to be University), Visakhapatnam, Andhra Pradesh, India
| | - Manish Pandey
- Department of Pharmaceutical Technology, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
- Department of Pharmaceutical Sciences, Central University of Haryana, Mahendergarh, India
| | - Jayashree Mayuren
- Department of Pharmaceutical Technology, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Chia Siang Kow
- Department of Pharmacy Practice, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
| | - Mayuren Candasamy
- Department of Life Sciences, School of Pharmacy, International Medical University, Kuala Lumpur, Malaysia
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Li N, Flanagan BA, Edmands S. The role of mitochondria in sex- and age-specific gene expression in a species without sex chromosomes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.12.08.570893. [PMID: 38106076 PMCID: PMC10723445 DOI: 10.1101/2023.12.08.570893] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2023]
Abstract
Mitochondria perform an array of functions, many of which involve interactions with gene products encoded by the nucleus. These mitochondrial functions, particularly those involving energy production, can be expected to differ between sexes and across ages. Here we measured mitochondrial effects on sex- and age-specific gene expression in parental and reciprocal F1 hybrids between allopatric populations of Tigriopus californicus with over 20% mitochondrial DNA divergence. Because the species lacks sex chromosomes, sex-biased mitochondrial effects are not confounded by the effects of sex chromosomes. Using single-individual RNA sequencing, sex differences were found to explain more than 80% of the variance in gene expression. Males had higher expression of mitochondrial genes and mitochondrially targeted proteins (MTPs) involved in oxidative phosphorylation (OXPHOS), while females had elevated expression of non-OXPHOS MTPs, indicating strongly sex-dimorphic energy metabolism at the whole organism level. Comparison of reciprocal F1 hybrids allowed insights into the nature of mito-nuclear interactions, showing both mitochondrial effects on nuclear expression, as well as nuclear effects on mitochondrial expression. Across both sexes, increases in mitochondrial expression with age were associated with longer life. Network analyses identified nuclear components of strong mito-nuclear interactions, and found them to be sexually dimorphic. These results highlight the profound impact of mitochondria and mito-nuclear interactions on sex- and age-specific gene expression.
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Affiliation(s)
- Ning Li
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
| | | | - Suzanne Edmands
- Department of Biological Sciences, University of Southern California, 3616 Trousdale Parkway, Los Angeles, CA 90089, USA
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4
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Torres-Gonzalez E, Makova KD. Exploring the Effects of Mitonuclear Interactions on Mitochondrial DNA Gene Expression in Humans. Front Genet 2022; 13:797129. [PMID: 35846132 PMCID: PMC9277102 DOI: 10.3389/fgene.2022.797129] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2021] [Accepted: 05/30/2022] [Indexed: 11/13/2022] Open
Abstract
Most mitochondrial protein complexes include both nuclear and mitochondrial gene products, which coevolved to work together. This coevolution can be disrupted due to disparity in genetic ancestry between the nuclear and mitochondrial genomes in recently admixed populations. Such mitonuclear DNA discordance might result in phenotypic effects. Several nuclear-encoded proteins regulate expression of mitochondrial DNA (mtDNA) genes. We hypothesized that mitonuclear DNA discordance affects expression of genes encoded by mtDNA. To test this, we utilized the data from the GTEx project, which contains expression levels for ∼100 African Americans and >600 European Americans. The varying proportion of African and European ancestry in recently admixed African Americans provides a range of mitonuclear discordance values, which can be correlated with mtDNA gene expression levels (adjusted for age and ischemic time). In contrast, European Americans did not undergo recent admixture. We demonstrated that, for most mtDNA protein-coding genes, expression levels in energetically-demanding tissues were lower in African Americans than in European Americans. Furthermore, gene expression levels were lower in individuals with higher mitonuclear discordance, independent of population. Moreover, we found a negative correlation between mtDNA gene expression and mitonuclear discordance. In African Americans, the average value of African ancestry was higher for nuclear-encoded mitochondrial than non-mitochondrial genes, facilitating a match in ancestry with the mtDNA and more optimal interactions. These results represent an example of a phenotypic effect of mitonuclear discordance on human admixed populations, and have potential biomedical applications.
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Affiliation(s)
| | - Kateryna D. Makova
- Department of Biology, The Pennsylvania State University, University Park, PA, United States
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5
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An in-depth analysis of the mitochondrial phylogenetic landscape of Cambodia. Sci Rep 2021; 11:10816. [PMID: 34031453 PMCID: PMC8144189 DOI: 10.1038/s41598-021-90145-2] [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: 03/25/2021] [Accepted: 05/07/2021] [Indexed: 11/08/2022] Open
Abstract
Cambodia harbours a variety of human aboriginal populations that have scarcely been studied in terms of genetic diversity of entire mitochondrial genomes. Here we present the matrilineal gene pool of 299 Cambodian refugees from three different ethnic groups (Cham, Khmer, and Khmer Loeu) deriving from 16 Cambodian districts. After establishing a DNA-saving high-throughput strategy for mitochondrial whole-genome Sanger sequencing, a HaploGrep based workflow was used for quality control, haplogroup classification and phylogenetic reconstruction. The application of diverse phylogenetic algorithms revealed an exciting picture of the genetic diversity of Cambodia, especially in relation to populations from Southeast Asia and from the whole world. A total of 224 unique haplotypes were identified, which were mostly classified under haplogroups B5a1, F1a1, or categorized as newly defined basal haplogroups or basal sub-branches of R, N and M clades. The presence of autochthonous maternal lineages could be confirmed as reported in previous studies. The exceptional homogeneity observed between and within the three investigated Cambodian ethnic groups indicates genetic isolation of the whole population. Between ethnicities, genetic barriers were not detected. The mtDNA data presented here increases the phylogenetic resolution in Cambodia significantly, thereby highlighting the need for an update of the current human mtDNA phylogeny.
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Sharma H, Singh D, Mahant A, Sohal SK, Kesavan AK, Samiksha. Development of mitochondrial replacement therapy: A review. Heliyon 2020; 6:e04643. [PMID: 32984570 PMCID: PMC7492815 DOI: 10.1016/j.heliyon.2020.e04643] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 06/10/2020] [Accepted: 08/03/2020] [Indexed: 12/19/2022] Open
Abstract
Mitochondrial replacement therapy (MRT) is a new form of reproductive invitro fertilization (IVF) which works on the principle of replacing a women's abnormal mitochondrial DNA (mt-DNA) with the donor's healthy one. MRT include different techniques like spindles transfer (ST), pronuclear transfer (PNT) or polar body transfer (PBT). Transmission of defective mitochondrial DNA to the next generation can also be prevented by using these approaches. The development of healthy baby free from genetic disorders and to terminate the lethal mitochondrial disorders are the chief motive of this technique. In aged individuals, through in vitro fertilization, MRT provides the substitution of defective cytoplasm with cured one to enhance the expectation of pregnancy rates. However, moral, social, and cultural objections have restricted its exploration. Therefore, this review summarizes the various methods involved in MRT, its global status, its exaggerated censure over the years which depicts a strong emphasis for social acceptance and clinical application in the world of medical science.
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Affiliation(s)
- Hitika Sharma
- Department of Zoology, Khalsa College Amritsar, Punjab, 143005, India
| | - Drishtant Singh
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | | | - Satwinder Kaur Sohal
- Department of Zoology, Guru Nanak Dev University Amritsar, Punjab, 143005, India
| | - Anup Kumar Kesavan
- Department of Molecular Biology and Biochemistry, Guru Nanak Dev University, Amritsar, Punjab, 143005, India
| | - Samiksha
- Department of Zoology, Guru Nanak Dev University Amritsar, Punjab, 143005, India
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Hill GE, Havird JC, Sloan DB, Burton RS, Greening C, Dowling DK. Assessing the fitness consequences of mitonuclear interactions in natural populations. Biol Rev Camb Philos Soc 2019; 94:1089-1104. [PMID: 30588726 PMCID: PMC6613652 DOI: 10.1111/brv.12493] [Citation(s) in RCA: 68] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2018] [Revised: 11/27/2018] [Accepted: 11/30/2018] [Indexed: 12/22/2022]
Abstract
Metazoans exist only with a continuous and rich supply of chemical energy from oxidative phosphorylation in mitochondria. The oxidative phosphorylation machinery that mediates energy conservation is encoded by both mitochondrial and nuclear genes, and hence the products of these two genomes must interact closely to achieve coordinated function of core respiratory processes. It follows that selection for efficient respiration will lead to selection for compatible combinations of mitochondrial and nuclear genotypes, and this should facilitate coadaptation between mitochondrial and nuclear genomes (mitonuclear coadaptation). Herein, we outline the modes by which mitochondrial and nuclear genomes may coevolve within natural populations, and we discuss the implications of mitonuclear coadaptation for diverse fields of study in the biological sciences. We identify five themes in the study of mitonuclear interactions that provide a roadmap for both ecological and biomedical studies seeking to measure the contribution of intergenomic coadaptation to the evolution of natural populations. We also explore the wider implications of the fitness consequences of mitonuclear interactions, focusing on central debates within the fields of ecology and biomedicine.
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Affiliation(s)
- Geoffrey E. Hill
- Department of Biological Sciences, Auburn University, United States of America
| | - Justin C. Havird
- Department of Biology, Colorado State University, United States of America
| | - Daniel B. Sloan
- Department of Biology, Colorado State University, United States of America
| | - Ronald S. Burton
- Scripps Institution of Oceanography, University of California, San Diego, United States of America
| | - Chris Greening
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
| | - Damian K. Dowling
- School of Biological Sciences, Monash University, Clayton, Victoria 3800, Australia
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Rubeis G, Steger F. Ethische und konzeptuelle Aspekte des Mitochondrien-Transfers („Drei-Eltern-Kind“). Ethik Med 2019. [DOI: 10.1007/s00481-019-00523-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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9
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Investigating mitonuclear interactions in human admixed populations. Nat Ecol Evol 2019; 3:213-222. [PMID: 30643241 PMCID: PMC6925600 DOI: 10.1038/s41559-018-0766-1] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 11/22/2018] [Indexed: 12/13/2022]
Abstract
To function properly, mitochondria utilize products of 37 mitochondrial and >1,000 nuclear genes, which should be compatible with each other. Discordance between mitochondrial and nuclear genetic ancestry could contribute to phenotypic variation in admixed populations. Here, we explored potential mitonuclear incompatibility in six admixed human populations from the Americas: African Americans, African Caribbeans, Colombians, Mexicans, Peruvians and Puerto Ricans. By comparing nuclear versus mitochondrial ancestry in these populations, we first show that mitochondrial DNA (mtDNA) copy number decreases with increasing discordance between nuclear and mtDNA ancestry. The direction of this effect is consistent across mtDNA haplogroups of different geographic origins. This observation indicates suboptimal regulation of mtDNA replication when its components are encoded by nuclear and mtDNA genes with different ancestry. Second, while most populations analysed exhibit no such trend, in African Americans and Puerto Ricans, we find a significant enrichment of ancestry at nuclear-encoded mitochondrial genes towards the source populations contributing the most prevalent mtDNA haplogroups (African and Native American, respectively). This possibly reflects compensatory effects of selection in recovering mitonuclear interactions optimized in the source populations. Our results provide evidence of mitonuclear interactions in human admixed populations and we discuss their implications for human health and disease.
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10
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Mitochondrial Replacement Therapy: Are Mito-nuclear Interactions Likely To Be a Problem? Genetics 2017; 205:1365-1372. [PMID: 28360127 DOI: 10.1534/genetics.116.196436] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2016] [Accepted: 02/08/2017] [Indexed: 02/01/2023] Open
Abstract
It has been suggested that deleterious interactions between the mitochondrial and nuclear genomes could pose a problem for mitochondrial replacement therapy (MRT). This is because the mitochondrial genome is placed in a novel nuclear environment using this technique. In contrast, it is inherited with half the mother's genome during normal reproduction, a genome that it is relatively compatible with, since the mother is alive. Here, I review the evidence of whether mito-nuclear interactions are likely to pose a problem for MRT. The majority of the available experimental evidence, both in humans and other species, suggests that MRT is not harmful. These results are consistent with population genetic theory, which predicts that deleterious mito-nuclear interactions are unlikely to be much more prevalent in individuals born to MRT than normal reproduction, particularly in a species such as humans with low population differentiation. This is because selection is unlikely to be strong enough to establish significant linkage disequilibrium between the mitochondrial and nuclear genomes. These results are supported by a meta-analysis of 231 cases, from a variety of animals, in which the mitochondrial DNA (mtDNA) from one strain has been introgressed into the nuclear background of another strain of the same species. Overall, there is little tendency for introgression of mtDNA to be harmful.
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11
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Dimond R, Stephens N. Three persons, three genetic contributors, three parents: Mitochondrial donation, genetic parenting and the immutable grammar of the ‘three x x’. Health (London) 2017; 22:240-258. [DOI: 10.1177/1363459316689380] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
In 2015, two novel in vitro fertilisation techniques intended to prevent the inheritance of mitochondrial disease were legalised in the United Kingdom, following an intense period of inquiry including scientific reviews, public consultations, government guidance and debates within the Houses of Parliament. The techniques were controversial because (1) they introduced a third genetic contributor into the reproductive process and (2) they are germline, meaning this genetic change could then be passed down to subsequent generations. Drawing on the social worlds framework with a focus on implicated actors and discursive strategies, this article explores key features of the UK mitochondrial debates as they played out in real time through policy documents and public debate. First, it situates the technology within a repertoire of metaphors, emotional terminology and their politics. It then explores the immutable grammar of ‘three x x’ that formed a key component of the political debate, by focusing on how institutional reviews discursively negotiated uncertainty around genetic parentage and how beneficiaries were implicated and rendered distant. Following the 2016 announcement of the first baby born through mitochondrial donation (in Mexico) and several pregnancies (in the Ukraine), we close with a discussion about the specific nature of UK regulation within a global economy. Overall, this article contributes to a much needed sociological discussion about mitochondrial donation, emerging reproductive technologies and the cultural significance of genetic material and genetic relatedness.
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Sloan DB, Fields PD, Havird JC. Mitonuclear linkage disequilibrium in human populations. Proc Biol Sci 2016; 282:rspb.2015.1704. [PMID: 26378221 DOI: 10.1098/rspb.2015.1704] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
There is extensive evidence from model systems that disrupting associations between co-adapted mitochondrial and nuclear genotypes can lead to deleterious and even lethal consequences. While it is tempting to extrapolate from these observations and make inferences about the human-health effects of altering mitonuclear associations, the importance of such associations may vary greatly among species, depending on population genetics, demographic history and other factors. Remarkably, despite the extensive study of human population genetics, the statistical associations between nuclear and mitochondrial alleles remain largely uninvestigated. We analysed published population genomic data to test for signatures of historical selection to maintain mitonuclear associations, particularly those involving nuclear genes that encode mitochondrial-localized proteins (N-mt genes). We found that significant mitonuclear linkage disequilibrium (LD) exists throughout the human genome, but these associations were generally weak, which is consistent with the paucity of population genetic structure in humans. Although mitonuclear LD varied among genomic regions (with especially high levels on the X chromosome), N-mt genes were statistically indistinguishable from background levels, suggesting that selection on mitonuclear epistasis has not preferentially maintained associations involving this set of loci at a species-wide level. We discuss these findings in the context of the ongoing debate over mitochondrial replacement therapy.
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Affiliation(s)
- Daniel B Sloan
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Peter D Fields
- Zoological Institute, University of Basel, Vesalgasse 1, Basel, 4051, Switzerland
| | - Justin C Havird
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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Muir R, Diot A, Poulton J. Mitochondrial content is central to nuclear gene expression: Profound implications for human health. Bioessays 2016; 38:150-6. [PMID: 26725055 PMCID: PMC4819685 DOI: 10.1002/bies.201500105] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We review a recent paper in Genome Research by Guantes et al. showing that nuclear gene expression is influenced by the bioenergetic status of the mitochondria. The amount of energy that mitochondria make available for gene expression varies considerably. It depends on: the energetic demands of the tissue; the mitochondrial DNA (mtDNA) mutant load; the number of mitochondria; stressors present in the cell. Hence, when failing mitochondria place the cell in energy crisis there are major effects on gene expression affecting the risk of degenerative diseases, cancer and ageing. In 2015 the UK parliament approved a change in the regulation of IVF techniques, allowing "Mitochondrial replacement therapy" to become a reproductive choice for women at risk of transmitting mitochondrial disease to their children. This is the first time that this technique will be available. Therefore understanding the interaction between mitochondria and the nucleus has never been more important.
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Affiliation(s)
- Rebecca Muir
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Alan Diot
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
| | - Joanna Poulton
- Nuffield Department of Obstetrics and Gynaecology, University of Oxford, John Radcliffe Hospital, Oxford, UK
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Flynn T, Signal B, Johnson SL, Gemmell NJ. Mitochondrial genome diversity among six laboratory zebrafish (Danio rerio) strains. Mitochondrial DNA A DNA Mapp Seq Anal 2015; 27:4364-4371. [PMID: 26477802 DOI: 10.3109/19401736.2015.1089536] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
The mitochondrial genome (mtDNA) is distinct from the nuclear genome and is known to play a significant role in several disease phenotypes, such as longevity and fertility. Here we characterize the complete mitochondrial genomes (∼16 590 bp), and the extent of within and between strain variation for 27 adult zebrafish, representing five commonly used laboratory strains (AB, TL, HL, WIK, and SJD) and one line acquired from a local pet shop. These data were subsequently analyzed to determine the phylogenetic relationships between strains and ascertain if positive selection might be operating on any mtDNA genes. Relationships between strains are not entirely consistent with those observed previously using nuclear DNA. Further there is a substantial body of variation within current zebrafish lines, with 172 variants described across lines. Of these, 27 changes are non-synonymous and there is nominal evidence for positive selection in the mtDNA sequences at some of these sites. We further identify novel frameshift mutations in eight genes, which are all predicted to have functional consequences. Our study provides the first information on mtDNA diversity in zebrafish, identifies multiple non-synonymous substitutions and other mutations expected to have functional effects, and represents an important first step in establishing zebrafish as a model for investigating the phenotypic effects of mtDNA mutations.
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Affiliation(s)
- Tanya Flynn
- a Department of Biochemistry , University of Otago , Dunedin , New Zealand.,b Department of Anatomy , Allan Wilson Centre, University of Otago , Dunedin , New Zealand , and
| | - Beth Signal
- b Department of Anatomy , Allan Wilson Centre, University of Otago , Dunedin , New Zealand , and
| | - Sheri L Johnson
- b Department of Anatomy , Allan Wilson Centre, University of Otago , Dunedin , New Zealand , and.,c Department of Zoology , University of Otago , Dunedin , New Zealand
| | - Neil J Gemmell
- b Department of Anatomy , Allan Wilson Centre, University of Otago , Dunedin , New Zealand , and
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Abstract
There are, in mankind, two kinds of heredity: biological and cultural. Cultural inheritance makes possible for humans what no other organism can accomplish: the cumulative transmission of experience from generation to generation. In turn, cultural inheritance leads to cultural evolution, the prevailing mode of human adaptation. For the last few millennia, humans have been adapting the environments to their genes more often than their genes to the environments. Nevertheless, natural selection persists in modern humans, both as differential mortality and as differential fertility, although its intensity may decrease in the future. More than 2,000 human diseases and abnormalities have a genetic causation. Health care and the increasing feasibility of genetic therapy will, although slowly, augment the future incidence of hereditary ailments. Germ-line gene therapy could halt this increase, but at present, it is not technically feasible. The proposal to enhance the human genetic endowment by genetic cloning of eminent individuals is not warranted. Genomes can be cloned; individuals cannot. In the future, therapeutic cloning will bring enhanced possibilities for organ transplantation, nerve cells and tissue healing, and other health benefits.
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