Increased contribution of non-reference alleles in mitochondrial DNA (mtDNA) of Alzheimer's disease (AD) patients
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ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE49160 | GEO | 2014/03/11
SECONDARY ACCESSION(S): PRJNA213575
REPOSITORIES: GEO
Similar Datasets
Project description:Many observations suggest that mutations of mtDNA could be responsible of the neurodegenerative changes associated with AD. We examined the signal intensity of the four alleles for each mtDNA nucleotide position (np) in whole blood of AD patients and age-matched controls utilizing a resequencing array, the MitoChip v2.0, and identified 275 statistically different nps which all, with the exception of one, showed an increased contribution of non-reference alleles for AD patients. PCA and cluster analysis showed that 5 of these nps, characterized by low-level heteroplasmy, could discriminate AD from control subjects with 80% of cases correctly classified. This study included a total of 18 AD patients and 18 age-matched controls. Data acquisition was performed using the Affymetrix Genechip Command Console (AGCC) software and data analysis was carried out with GSEQ 4.1.
2014-03-11 | E-GEOD-49160 | biostudies-arrayexpress
Project description:This study aimed to evaluate single nucleotide substitutions in mtDNA and analyze their correlation with inflammatory biomarkers in elderly COVID-19 patients. A total of 30 COVID-19 patients and 33 older adult controls (aged over 65 years) were enrolled. mtDNA was extracted from buffy coat samples and sequenced using a chip-based resequencing system (Affymetrix MitoChip v2.0) which detects both homoplasmic and heteroplasmic mtDNA mutations, and allows the assessment of low-level heteroplasmy. Serum concentration of IL-6, IFN-α, TNF-α and IL-10 were determined in patients by a high-sensitivity immunoassay. We found a higher burden of total heteroplasmic mutation in COVID-19 patients compared to controls with a selective increment in ND1 and COIII genes. Low-level heteroplasmy was significantly elevated in COVID-19 patients, especially in genes of the respiratory complex I. Both heteroplasmic mutation burden and low-level heteroplasmy were associated with increased levels of IL-6, TNF-α, and IFN-α.
2024-01-23 | GSE235626 | GEO
Project description:To address the question of whether mtDNA mutations might play a role in familiar ALS (fALS), mtDNA was isolated from whole blood (WB), white blood cells (WBC) and platelets (PLT) from fALS patients and the mitochondrial genome was analyzed using a mtDNA resequencing array (Affymetrix MitoChip v2.0) that allows detection of low-level heteroplasmy in addition to the conventional homoplasmic or heteroplasmic mutations. We distinguished between fALS cases with a prominent maternal (mat) inheritance pattern and fALS cases that do not point to a maternal inheritance pattern (non-mat). As additional controls we compared our results to healthy age and sex matched individuals without any known neurodegenerative background. With this we are aiming to get a deeper insight into a possible role of mtDNA alterations acting as a disease modifier in a subgroup of ALS patients presenting with a maternal transmission of the disease.
2023-07-28 | GSE211250 | GEO
Project description:Mitochondria generate signals of adaptation that regulate nuclear genes expression via retrograde signaling. But this phenomenon is complexified when qualitatively different mitochondria and mitochondrial DNA (mtDNA) coexist within cells. Although this cellular state of heteroplasmy leads to divergent phenotypes clinically, its consequences on cellular function and the cellular transcriptome are unknown. To interrogate this phenomenon, we generated somatic cell cybrids harboring increasing levels of a common mtDNA mutation (tRNALeu(UUR) 3243A>G) and mapped the resulting cellular phenotypes and transcriptional profiles across the complete range of heteroplasmy. Small increases in mutant mtDNAs caused relatively modest defect in mitochondrial oxidative capacity, but resulted in sharp transitions in mitochondrial ultrastructure and in the nuclear and mitochondrial transcriptomes, with the critical functional threshold corresponding to the induction of epigenetic regulatory systems. Principal component analysis underscores how each heteroplasmy level occupies a different "transcriptional space", with low levels heteroplasmy (20-30%) producing a dose-response linear progression in one direction, and mutationload of 50, 60 and 90% producing changes in the opposite direction. Hence, subtle changes in mitochondrial energetics can act through the epigenome to generate the phenotypes of the common “complex” diseases. Cells were generated by transferring the wildtype (3243A) and mutant (3243G) mtDNAs from a heteroplasmic 3243A>G patient’s lymphoblastoid cell line into 143B(TK-) mtDNA-deficient (ρo) cells and selected for transmitochondrial cybrids. Subsequent mtDNA depletion, reamplification, and cloning (Wiseman and Attardi, 1978) resulted in a series of stable cybrids harboring approximately 0, 20, 30, 50, 60, 90, and 100% 3243G mutant mtDNAs. Total RNA extracted from each cell line was then extracted, depleted of rRNA, and measured in sequenced in triplicates.
2014-09-02 | E-GEOD-56158 | biostudies-arrayexpress
Project description:Most humans carry a mixed population of mitochondrial DNA (mtDNA heteroplasmy) affecting ~1-2% of molecules, but rapid percentage shifts occur over one generation leading to severe mitochondrial diseases. A decrease in the amount of mtDNA within the developing female germ line appears to play a role, but other sub-cellular mechanisms have been implicated. Establishing an in vitro model of early mammalian germ cell development from embryonic stem cells, here we show the reduction of mtDNA content is modulated by oxygen and reaches a nadir immediately before germ cell specification. The observed genetic bottleneck was accompanied by a decrease in mtDNA replicating foci and the segregation of heteroplasmy, which were both abolished at higher oxygen levels. Thus, differences in oxygen tension during early development can modulate mtDNA segregation, facilitating germ-line purification, and contribute to tissue-specific somatic mutation loads.
2021-05-19 | GSE169427 | GEO
Project description:Mitochondria generate signals of adaptation that regulate nuclear genes expression via retrograde signaling. But this phenomenon is complexified when qualitatively different mitochondria and mitochondrial DNA (mtDNA) coexist within cells. Although this cellular state of heteroplasmy leads to divergent phenotypes clinically, its consequences on cellular function and the cellular transcriptome are unknown. To interrogate this phenomenon, we generated somatic cell cybrids harboring increasing levels of a common mtDNA mutation (tRNALeu(UUR) 3243A>G) and mapped the resulting cellular phenotypes and transcriptional profiles across the complete range of heteroplasmy. Small increases in mutant mtDNAs caused relatively modest defect in mitochondrial oxidative capacity, but resulted in sharp transitions in mitochondrial ultrastructure and in the nuclear and mitochondrial transcriptomes, with the critical functional threshold corresponding to the induction of epigenetic regulatory systems. Principal component analysis underscores how each heteroplasmy level occupies a different "transcriptional space", with low levels heteroplasmy (20-30%) producing a dose-response linear progression in one direction, and mutationload of 50, 60 and 90% producing changes in the opposite direction. Hence, subtle changes in mitochondrial energetics can act through the epigenome to generate the phenotypes of the common “complex” diseases.
2014-09-02 | GSE56158 | GEO
Project description:Mitochondrial DNA (mtDNA) encodes essential machinery for respiration and metabolic homeostasis but is paradoxically among the most common targets of somatic mutations in the cancer genome, with truncating mutations in complex I genes being over-represented1 . While mtDNA mutations have been associated with both improved and worsened prognoses in several cancer lineages1–3, whether these mutations are drivers, or exert any functional effect on tumour biology remains controversial. Here we discover that complex I-encoding mtDNA mutations are sufficient to remodel the tumour immune landscape and therapeutic resistance to immune checkpoint blockade. Using mtDNA base editing technology we engineered recurrent truncating mutations in the mtDNA-encoded complex I gene, Mt-Nd5, into murine models of melanoma. Mechanistically, these mutations promoted utilisation of pyruvate as a terminal electron acceptor and increased glycolytic flux driven by an over-reduced NAD pool and NADH shuttling between GAPDH and MDH1, mediating a Warburg-like metabolic shift. In turn, without modifying tumour growth, this altered cancer cell-intrinsic metabolism reshaped the tumour microenvironment of mouse and human cancer in a mutation load-dependent fashion, encouraging an anti-tumour immune response. This subsequently sensitises both mouse and human cancers with high mtDNA mutant heteroplasmy to immune checkpoint blockade. Strikingly, patient lesions bearing >50% mtDNA mutation load demonstrated a >2.5-fold improved response rate to checkpoint inhibitor blockade. Taken together these data nominate mtDNA mutations as functional regulators of cancer metabolism and tumour biology, with potential for therapeutic exploitation and treatment stratification.
2023-11-08 | PXD039705 | Pride
Project description:Mitochondrial DNA (mtDNA) encodes essential machinery for respiration and metabolic homeostasis but is paradoxically among the most common targets of somatic mutations in the cancer genome, with truncating mutations in complex I genes being over-represented1 . While mtDNA mutations have been associated with both improved and worsened prognoses in several cancer lineages1–3, whether these mutations are drivers, or exert any functional effect on tumour biology remains controversial. Here we discover that complex I-encoding mtDNA mutations are sufficient to remodel the tumour immune landscape and therapeutic resistance to immune checkpoint blockade. Using mtDNA base editing technology we engineered recurrent truncating mutations in the mtDNA-encoded complex I gene, Mt-Nd5, into murine models of melanoma. Mechanistically, these mutations promoted utilisation of pyruvate as a terminal electron acceptor and increased glycolytic flux driven by an over-reduced NAD pool and NADH shuttling between GAPDH and MDH1, mediating a Warburg-like metabolic shift. In turn, without modifying tumour growth, this altered cancer cell-intrinsic metabolism reshaped the tumour microenvironment of mouse and human cancer in a mutation load-dependent fashion, encouraging an anti-tumour immune response. This subsequently sensitises both mouse and human cancers with high mtDNA mutant heteroplasmy to immune checkpoint blockade. Strikingly, patient lesions bearing >50% mtDNA mutation load demonstrated a >2.5-fold improved response rate to checkpoint inhibitor blockade. Taken together these data nominate mtDNA mutations as functional regulators of cancer metabolism and tumour biology, with potential for therapeutic exploitation and treatment stratification.
2023-11-08 | PXD044987 | Pride
Project description:Mitochondria are vital due to their principal role in energy production via oxidative phosphorylation (OXPHOS)1. Mitochondria carry their own genome (mtDNA) encoding critical genes involved in OXPHOS, therefore, mtDNA mutations cause fatal or severely debilitating disorders with limited treatment options. 2. Clinical manifestations of mtDNA disease vary based on mutation type and heteroplasmy levels i.e. presence of mutant and normal mtDNA within each cell. 3,4. We evaluated therapeutic concepts of generating genetically corrected pluripotent stem cells for patients with mtDNA mutations. We initially generated multiple iPS cell lines from a patient with mitochondrial encephalomyopathy and stroke-like episodes (MELAS) caused by a heteroplasmic 3243A>G mutation and a patient with Leigh disease carrying a homoplasmic 8993T>G mutation (Leigh-iPS). Due to spontaneous mtDNA segregation in proliferating fibroblasts, isogenic MELAS iPS cell lines were recovered containing exclusively wild type (wt) mtDNA with normal metabolic function. As expected, all iPS cells from the patient with Leigh disease were affected. Using somatic cell nuclear transfer (SCNT; Leigh-NT1), we then simultaneously replaced mutated mtDNA and generated pluripotent stem cells from the Leigh patient fibroblasts. In addition to reversing to a normal 8993G>T, oocyte derived donor mtDNA (human haplotype D4a) in Leigh-NT1 differed from the original haplotype (F1a) at a additional 47 nucleotide sites. Leigh-NT1 cells displayed normal metabolic function compared to impaired oxygen consumption and ATP production in Leigh-iPS cells or parental fibroblasts (Leigh-fib). We conclude that natural segregation of heteroplasmic mtDNA allows the generation of iPS cells with exclusively wild type mtDNA. Moreover, SCNT offers mitochondrial gene replacement strategy for patients with homoplasmic mtDNA disease.
2015-07-16 | GSE61390 | GEO
Project description:We evaluated here the physiological consequences of the generation of heteroplasmic embryos by mix of two wild type mtDNAs in the same zygote. In this animal model, mtDNA heteroplasmy is actively combated during germ-line transmission, embryonic development and somatic life of most differentiated cells. mtDNA heteroplasmy alone, even when both mtDNA types are individually non-pathogenic, causes a disease affecting mainly those tissues that are not able to reduce their heteroplasmy: heart, lung and skeletal muscle.
2020-01-01 | GSE93920 | GEO