Ena-DATASET-UDS-13-06-2016-13:27:17:602-267 - samples
Ontology highlight
ABSTRACT:
PROVIDER: EGAD00001002189 | EGA |
REPOSITORIES: EGA
Publications
Mitochondrial DNA Variation and Heteroplasmy in Monozygotic Twins Clinically Discordant for Multiple Sclerosis.
Souren Nicole Y P NY Gerdes Lisa A LA Kümpfel Tania T Lutsik Pavlo P Klopstock Thomas T Hohlfeld Reinhard R Walter Jörn J
Human mutation 20160513 8
We examined the debated link between mitochondrial DNA (mtDNA) variation and multiple sclerosis (MS) using 49 monozygotic (MZ) twin pairs clinically discordant for MS, which enables to associate de novo mtDNA variants, skewed heteroplasmy, and mtDNA copy number with MS manifestation. Ultra-deep sequencing of blood-derived mtDNA revealed 25 heteroplasmic variants with potentially pathogenic features in 18 pairs. All variants were pair-specific and had low and/or similar heteroplasmy levels in bot ...[more]
Similar Datasets
Project description:Several lines of evidence indicate that mitochondrial DNA (mtDNA) variants might predispose to multiple sclerosis (MS). We examined this in 49 monozygotic (MZ) twin pairs clinically discordant for MS at study entry. Since the nuclear DNA of MZ twins is identical, our study provides a unique setting to functionally associate unique mtDNA variants and skewed heteroplasmy with MS development. In order to identify mtDNA variants in the twin cohort, we deeply sequenced the mitochondrial genome in blood of all 49 MZ twin pairs using next generation sequencing (Illumina, HiSeq or MiSeq) with an average coverage depth of ~25,000 sequences per base. Heteroplasmic variants were validated using targeted deep sequencing (TDS) (Illumina, MiSeq) in DNA isolated from blood and buccal swabs. In addition, whole blood was also available of 5 additional MS-affected or healthy siblings and 1 dizygotic twin pair discordant for MS, comprising in total 6 non-identical sib pairs. Moreover, all cases were screened for pathogenic mtDNA polymerase gamma (POLG) mutations. The data provides valuable insights in the possible involvement of mtDNA variants in the pathogenesis of MS, and gives information on the segregation of heteroplasmic variants within MZ twins and non-identical siblings and across different tissues.
| EGAS00001001240 | EGA
Project description:Pathogenic mutations in the catalytic DNA polymerase gamma (POLG1) gene result in the accumulation of mtDNA mutations, deletions and/or decrease of mtDNA copy number. These features interfere with proper functioning of the electron transport chain, mostly affecting metabolically active tissues such as the brain, the heart and the liver. So far, mechanisms underlying POLG pathogenesis are not fully understood. To identify general pathways influenced by mutant polymerase gamma, skeletal muscle gene expression profiles of six POLG1 patients and twelve controls were compared. Patient and control subject from three age categories (<10; 11-49; >50) were selected. RNA was extracted from skeletal muscle biopsies and hybridized on Affymetrix microarrays.
2016-07-03 | E-GEOD-18715 | biostudies-arrayexpress
Project description:Pathogenic mutations in the catalytic DNA polymerase gamma (POLG1) gene result in the accumulation of mtDNA mutations, deletions and/or decrease of mtDNA copy number. These features interfere with proper functioning of the electron transport chain, mostly affecting metabolically active tissues such as the brain, the heart and the liver. So far, mechanisms underlying POLG pathogenesis are not fully understood. To identify general pathways influenced by mutant polymerase gamma, skeletal muscle gene expression profiles of six POLG1 patients and twelve controls were compared.
2016-01-01 | GSE18715 | GEO
Project description:Previous work has demonstrated the presence of ribonucleotides in human mitochondrial DNA (mtDNA) and in the present study we use a genome-wide approach to precisely map the location of these. We find that ribonucleotides are distributed evenly between the heavy- and light-strand of mtDNA. The relative levels of incorporated ribonucleotides reflect that DNA polymerase γ discriminates the four ribonucleotides differentially during DNA synthesis. The observed pattern is also dependent on the mitochondrial deoxyribonucleotide (dNTP) pools and disease-causing mutations that change these pools alter both the absolute and relative levels of incorporated ribonucleotides. Our analyses strongly suggest that DNA polymerase γ-dependent incorporation is the main source of ribonucleotides in mtDNA and argues against the existence of a mitochondrial ribonucleotide excision repair pathway in human cells. Furthermore, we clearly demonstrate that when dNTP pools are limiting, ribonucleotides serve as a source of building blocks to maintain DNA replication and genome stability. Increased levels of embedded ribonucleotides in patient cells with disturbed nucleotide pools may constitute to a pathogenic mechanism that affects mtDNA stability and impair new rounds of mtDNA replication
2017-02-13 | GSE90054 | GEO
Project description:Mitochondrial dysfunction is implicated in aging and aging-related disorders, such as neurodegenerative diseases and stroke. To study the effects of progressive mitochondrial dysfunction, a homozygous knock-in mouse expressing a proof-reading deficient version of the nucleus-encoded catalytic subunit of mitochondrial DNA (mtDNA) polymerase (PolgA) has been developed. In the mtDNA mutator mouse the proofreading activity of PolgA has been abolished by a single amino acid change. PolgA is the catalytic subunit of the polymerase gamma, which is involved in replicating and proofreading the mitochondrial DNA. As a result, mtDNA mutator mice develop high levels of point mutations and linear deletions, which lead to several human-like phenotypes associated with aging, including reduced lifespan (42-44 weeks), weight loss, alopecia, anemia, kyphosis, osteoporosis, sarcopenia, loss of subcutaneous fat, and reduced fertility. We investigate the molecular mechanism through which exercise may improve the phenotype of the mtDNA mutator mouse, which is a model of premature aging induced by mitochondrial dysfunction. Remarkably, forced endurance exercise has been shown to rescue the progeroid aging phenotypes of the mtDNA mutator mice, and to induce systemic mitochondrial rejuvenation. Here, using voluntary, rather than forced exercise, we investigate the molecular mechanisms underlying such a dramatic improvement, and also assess the effect of exercise on brain tissues, such as cortex and striatum in our model. The complete proteome of key tissues (muscle, brain cortex, brain striatum) from exercising and sedentary mtDNA mutator mice as well as exercising and sedentary wild type mice is quantified using peptide high-resolution isoelectric focusing (HiRIEF) coupled with liquid chromatography tandem mass spectrometry (LC-MS/MS) with an isobaric tag (TMT10plex) strategy.
2019-08-05 | PXD011741 | Pride
Project description:To gain insight into the etiopathogenesis of Multiple sclerosis (MS) we investigated gene expression changes in CD4+ and CD8+ T lymphocytes from monozygotic twins (MZ) discordant for relapsing remitting MS. We studied 4 monozygotic twin pairs discordant for disease, with the affected co-twin free of disease modifying therapies (F/M = 3/1, mean age 36.25±3.9). Following leukapheresis, CD4+ and CD8+ T cells were separated and studied by Affymetrix GeneChip®
2010-12-31 | GSE16461 | GEO
Project description:<p>Monozygotic (MZ) twins have been widely employed for dissection of the relative contributions of genetics and environment in disease. In multiple sclerosis (MS), an autoimmune demyelinating disease that commonly causes neurodegeneration and disability in young adults, disease discordance in MZ twins has been interpreted to indicate environmental importance in pathogenesis. However, genetic and epigenetic differences between MZ twins have been described, challenging the accepted experimental paradigm in disambiguating effects of nature and nurture. Here, we report the genome sequences of one MS-discordant MZ twin pair and messenger RNA (mRNA) transcriptome and epigenome sequences of CD4+ lymphocytes from three MS-discordant, MZ twin pairs. No reproducible differences were detected between co-twins among ~3.6 million single nucleotide polymorphisms (SNPs) or ~0.2 million insertion-deletion polymorphisms (indels). Nor were any reproducible differences observed between siblings of the three twin pairs in HLA haplotypes, confirmed MS-susceptibility SNPs, copy number variations, mRNA and genomic SNP and indel genotypes, or expression of ~19,000 genes in CD4+ T cells. Only two to 176 differences in methylation of ~2 million CpG sites were detected between siblings of the three twin pairs, in contrast to ~800 differences in methylation between T cells of unrelated individuals and several thousand differences between tissues or normal and cancerous tissues. In the first systematic effort to estimate sequence variation among MZ co-twins, we did not find evidence for genetic, epigenetic or transcriptome differences that explained disease discordance. These are the first female, twin and autoimmune disease genome sequences reported.</p>
| phs000239 | dbGaP
Project description:Exercise is a fundamental component of human health that is associated with greater life expectancy and reduced risk of chronic diseases. While the beneficial effects of endurance exercise on human health are well established, the molecular mechanisms responsible for these observations remain unclear. Endurance exercise reduces the accumulation of mitochondrial DNA (mtDNA) mutations, alleviates multisystem pathology, and increases the lifespan of the mtDNA mutator mouse model of aging, in which the proof-reading capacity of mitochondrial polymerase gamma (POLG1) is deficient. Clearly, exercise recruited a POLG1-independent mtDNA repair pathway to induce these adaptations, a novel finding as POLG1 is canonically considered to be the sole mtDNA repair enzyme. Here we investigate the identity of this pathway, and show that endurance exercise prevents mitochondrial oxidative damage, attenuates telomere erosion, and mitigates cellular senescence and apoptosis in mtDNA mutator mice. Unexpectedly, we observe translocation of tumour suppressor protein p53 to mitochondria in response to endurance exercise that facilitates mtDNA mutation repair. Indeed, endurance exercise failed to prevent mtDNA mutations, induce mitochondrial biogenesis, preserve mitochondrial morphology, reverse sarcopenia, and mitigate premature mortality in mtDNA mutator mice with muscle-specific deletion of p53. Our data establish an exciting new role for p53 in exercise-mediated maintenance of the mtDNA genome, and presents mitochondrially-targeted p53 as a novel therapeutic modality for aging-associated diseases of mitochondrial etiology. Microarray analysis of gene expression from skeletal muscle (quadriceps femoris) from Mus musculus. N=23 samples per treatment were analysed for whole transcriptiome gene expression profile using NimbleGen Arrays. The treatment groups included wild-type C57Bl/6J mice as the control group, then two treatment groups which both contained homozygous knock-in mtDNA mutator mice (PolG; PolgAD257A/D257A). Once group of these heterozygous knock out mice received regular endurance exercise sessions while the other group remained sedentraty for 6 months. The control group specimens were wild-type litter mates to the transgenic knockout mice.
2015-12-11 | E-GEOD-75869 | biostudies-arrayexpress
Project description:Single-end BAM files of the targeted deep sequencing analysis of several mtDNA candidate regions in blood and buccal-derived DNA of the corresponding twin pairs.
| EGAD00001002190 | EGA
Project description:Mitochondrial DNA (mtDNA) mutations may contribute to aging and age-related disorders. Previously, we created mice expressing a proofreading-deficient version of the mtDNA polymerase gamma (Polg) which accumulate age-related mtDNA mutations and display premature aging. Here we performed microarray gene expression profiling to identify mtDNA mutation-responsive genes in the cochlea of aged mitochondrial mutator mice. Age-related accumulation of mtDNA mutations was associated with transcriptional alternations consistent with reduced inner ear function, mitochondrial dysfunction, neurodegeneration, and reduced cell structural modulation. Hearing assessment and histopathological results confirmed that aged PolgD257A/D257A (D257A) mice exhibited moderate hearing loss and severe cochlear degenerations. Age-related accumulation of mtDNA mutations also resulted in alternations in gene expression consistent with induction of apoptosis, proteolysis, stress response, and reduced DNA repair. TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling) assay confirmed that the cochleae from aged D257A mice showed significantly more TUNEL positive cells compared to wild-type (WT) mice. The levels of cleaved caspase-3 were also found to increase in the cochleae of aged D257A mice. These observations provide evidence that age-related accumulation of mtDNA mutations is associated with apoptotic cell death in aged cochlea. Our results provide the first global view of molecular events associated with mtDNA mutations in postmitotic tissue, and suggest that apoptosis is the major mechanism of mtDNA mediated cell death in the development of age-related hearing disorder. Experiment Overall Design: To determine the effects of age-related accumulation of mtDNA mutations, each WT sample (n = 5) was compared to each D257A sample (n = 5), generating a total of twenty-five pairwise comparisons. Genes with significantly altered expression levels were sorted into gene ontology biological process categories. Experiment Overall Design: Gene expression change was called statistically significant when at least one gene was called present in a group, the P value was < 0.0500, FC was > 1.1, and FDR was > 30.00 for identification of mtDNA mutations-induced genes. Experiment Overall Design: Affymetrix standard spike controls were used in all experiments (eukaryotic hybridization control kit). Quality control measures were not used. No replicates were done. Dye swap was not used.
2008-11-07 | E-GEOD-4866 | biostudies-arrayexpress