MtDNA sequencing of aged muscle stem cells (mouse)
Ontology highlight
ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE180953 | GEO | 2021/07/29
REPOSITORIES: GEO
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Project description:Somatic mitochondrial DNA (mtDNA) mutations contribute to the pathogenesis of age-related disorders, including myelodysplastic syndromes (MDS). The accumulation of mitochondria harboring mtDNA mutations in patients with these disorders suggests a failure of normal mitochondrial quality-control systems. The mtDNA-mutator mice acquire somatic mtDNA mutations via a targeted defect in the proofreading function of the mtDNA polymerase, PolgA, and develop macrocyticanemia similar to that of patients with MDS. We observed an unexpected defect in clearance of dysfunctional mitochondria at specific stages during erythroid maturation in hematopoietic cells from aged mtDNA-mutator mice. Mechanistically, aberrant activation of mechanistic target of rapamycin signaling and phosphorylation of uncoordinated 51-like kinase (ULK) 1 in mtDNA-mutator mice resulted in proteasome mediated degradation of ULK1 and inhibition of autophagy in erythroid cells. To directly evaluate the consequence of inhibiting autophagy on mitochondrial function in erythroid cells harboring mtDNA mutations in vivo, we deleted Atg7 from erythroid progenitors of wildtype and mtDNA-mutator mice. Genetic disruption of autophagy did not cause anemia in wild-type mice but accelerated the decline in mitochondrial respiration and development of macrocytic anemia in mtDNA-mutator mice. These findings highlight a pathological feedback loop that explains how dysfunctional mitochondria can escape autophagy-mediated degradation and propagate in cells predisposed to somatic mtDNA mutations, leading to disease. We used microarrays to identify expression profiles and pathways that are differentially activated or suppressed in Ter119+ bone marrow cells isolated from phlebotomized wildtype or Polg mutant mice
2015-04-21 | E-GEOD-57761 | biostudies-arrayexpress
Project description:mtDNA sequencing of aged muscle stem cells (mouse)
| PRJNA750139 | ENA
Project description:Somatic mitochondrial DNA (mtDNA) mutations contribute to the pathogenesis of age-related disorders, including myelodysplastic syndromes (MDS). The accumulation of mitochondria harboring mtDNA mutations in patients with these disorders suggests a failure of normal mitochondrial quality-control systems. The mtDNA-mutator mice acquire somatic mtDNA mutations via a targeted defect in the proofreading function of the mtDNA polymerase, PolgA, and develop macrocytic anemia similar to that of patients with MDS. We observed an unexpected defect in clearance of dysfunctional mitochondria at specific stages during erythroid maturation in hematopoietic cells from aged mtDNA-mutator mice. Mechanistically, aberrant activation of mechanistic target of rapamycin signaling and phosphorylation of uncoordinated 51-like kinase (ULK) 1 in mtDNA-mutator mice resulted in proteasome mediated degradation of ULK1 and inhibition of autophagy in erythroid cells. To directly evaluate the consequence of inhibiting autophagy on mitochondrial function in erythroid cells harboring mtDNA mutations in vivo, we deleted Atg7 from erythroid progenitors of wildtype and mtDNA-mutator mice. Genetic disruption of autophagy did not cause anemia in wild-type mice but accelerated the decline in mitochondrial respiration and development of macrocytic anemia in mtDNA-mutator mice. These findings highlight a pathological feedback loop that explains how dysfunctional mitochondria can escape autophagy-mediated degradation and propagate in cells predisposed to somatic mtDNA mutations, leading to disease.
2015-04-21 | GSE57761 | GEO
Project description:Mitochondrial DNA (mtDNA) breaks are deleterious lesions that lead to degradation of mitochondrial genomes and subsequent reduction in mtDNA copy number. The signaling pathways activated in response to mtDNA damage remain ill-defined. Using mitochondrial targeted restriction enzymes, we show that cells with mtDNA breaks exhibit reduced respiratory complexes, loss of membrane potential, and mitochondrial protein import defect. Furthermore, mtDNA damage activates the integrated stress response (ISR) through phosphorylation of eIF2α by the OMA1-DELE1-HRI pathway. Electron microscopy reveals concomitant defects in mitochondrial membranes and cristae ultrastructure. Notably, inhibition of the ISR exacerbates mitochondrial defects and delays the recovery of mtDNA copy number, thereby implicating this stress response in mitigating mitochondrial dysfunction following mtDNA damage. Last, we provide evidence suggesting that ATAD3A, a membrane-anchored protein that interacts with nucleoids, relays the signal from mtDNA breaks to the inner mitochondrial membrane. Altogether, our study fully delineates the sequence of events linking damaged mitochondrial genomes with the cytoplasm and uncovers an unanticipated role for the ISR in response to mitochondrial genome instability.
2022-10-04 | GSE214512 | GEO
Project description:Damage to the mitochondrial genome (mtDNA) severely affects the cell and causes disease. Mutations to mtDNA also accumulate throughout the lifespan of many organisms and may be a proximal cause of aging. There is no effective treatment for ailments caused by mtDNA mutation. Since mitochondrial function and biogenesis are controlled by the nutrient environment of the cell, it is possible that perturbation of conserved, nutrient-sensing pathways may successfully treat mitochondrial disease. Experiments using the tractable eukaryote Saccharomyces cerevisiae allow us to investigate the connection between nutrient-sensing and mitochondrial function. We have focused our current studies on the protein kinase A (PKA) pathway, which controls S. cerevisiae behavior according to glucose availability. We found that reduced PKA signaling can lead, in a background-dependent manner, to improved fitness after mtDNA loss. Specifically, over-expression of the cyclic AMP phosphodiesterase Pde2p, removal of PKA isoform Tpk3p, or ablation of other proteins promoting PKA activity leads to improved proliferation of cells deleted of the mitochondrial genome. Over-expression of Pde2p also suppresses the inviability of several mutants that normally cannot survive mtDNA loss. Moreover, Pde2p over-expression diminishes the nuclear transcriptional response to mtDNA damage, further supporting the idea that glucose sensation is harmful for cells lacking the mitochondrial genome. These findings are heavily dependent upon yeast genetic background. Interestingly, robust import of mitochondrial polytopic membrane proteins may be required in order for cells with no mtDNA to receive the full benefits of PKA reduction. Our findings support the idea that perturbation of nutrient-sensing pathways, and specifically the sensation of glucose, may benefit cells with dysfunctional mitochondria. Four experimental conditions were used: BY4743 (WT) cells containing empty pRS426 vector and containing mtDNA because EtBr was not used, BY4743 (WT) cells containing empty pRS426 vector and lacking mtDNA after 24 hours of treatment with 25 µg/ml ethidium bromide, BY4743 (WT) cells overexpressing TIP41 from plasmid pRS426 and lacking mtDNA after 24 hours of treatment with 25 µg/ml ethidium bromide, and BY4743 (WT) cells overexpressing PDE2 from plasmid pRS426 and lacking mtDNA after 24 hours of treatment with 25 µg/ml ethidium bromide. Two replicates were performed for each sample type.
2015-08-07 | E-GEOD-71252 | biostudies-arrayexpress
Project description:RNAsequencing data from POLG D257A mutant mouse iPS (induced pluripotent stem) cells. These mice accumulate random point mutations in their mitochondrial genome and manifest progeric features. The reprogramming and phenotype of the cells is described in Hämäläinen et al. 2015, Cell reports, mtDNA Mutagenesis Disrupts Pluripotent Stem Cell Function by Altering Redox Signaling. The goal of the study was to analyze altered gene expression profiles between mutant and wt iPS cells to identify altered biological pathways responsible for the stemness and proliferation defects seem in mtDNA mutator stem cells.
2019-09-24 | GSE133259 | GEO
Project description:Purpose: To develop a pipeline (Splice-Break) for high-resolution quantification of mtDNA deletions, provide a catalogue of human mtDNA deletion breakpoints, and evaluate mtDNA deletions in brains from subjects with psychiatric disorders. Methods: 93 samples from human postmortem brain and blood were obtained from the Southwest Brain Bank (SBB) and University of California, Irvine (UCI) Brain Bank. Total DNA was extracted from frozen homogenate tissue and mtDNA was amplified/enriched using a single long-range PCR. Mitochondrial amplicons were purified by bead purification to retain both wild-type and deleted molecules (i.e., no gel excision was performed). mtDNA-enriched PCR amplicons were prepared for sequencing using standard Illumina protocols for DNA. Samples were sequenced 150-mer paired-end reads, in multiplex (96x per lane), on an unpatterned flowcell (HiSeq 2500). Fastq files were processed using our Splice-Break pipeline for the detection and relative quantification of mtDNA deletions. Results: A catalogue of 4,489 putative mitochondrial DNA (mtDNA) deletions, including their frequency and relative read rate, was produced. Analyses of 93 samples from postmortem brain and blood found 1) the 4,977bp “common deletion” was neither the most frequent deletion nor the most abundant; 2) brain contained significantly more mtDNA deletions than blood; 3) many high frequency deletions were previously reported in MitoBreak, suggesting they are present at low levels in metabolically active tissues and are not exclusive to individuals with diagnosed mitochondrial pathologies; 4) many individual deletions (and cumulative deletion metrics) had significant and positive correlations with age; and 5) the highest deletion burdens were observed in a subset of subjects with major depressive disorder (MDD), and these subjects had mtDNA deletion levels at or above those detected in typical deletion pathologies (e.g., Kearns-Sayre syndrome (KSS) muscle). Conclusions: Collectively, these data suggest the Splice-Break pipeline can detect and quantify mtDNA deletions at a high level of resolution.
2018-11-01 | GSE118615 | GEO
Project description:Mitochondria contain a 16kb-dsDNA genome encoding 13 proteins essential for respiration, whereas its regulatory mechanism and potential role in cancer development remain elusive. Although Methyl-CpG-binding protein (MBD) proteins are essential for nuclear transcription, their role in mitochondrial DNA (mtDNA) transcription is unknown. Here, we report that the MBD2c splicing variant translocates into mitochondria to mediate mtDNA transcription and increase mitochondrial respiration in triple negative breast cancer (TNBC) cells. Specifically, MBD2c binds D-loop regions in mtDNA to recruit SIRT3, which in turn deacetylates TFAM, a primary mitochondrial transcription factor, and activates its function. TFAM activation subsequently enhances transcription of the whole mitochondrial genome. Furthermore, MBD2c overexpression recovered the decreased mtDNA-encoded RNA and protein levels induced by the DNA synthesis inhibitor, cisplatin (CDDP), in vitro and in vivo, preserving mitochondrial gene expression and respiration, consequently enhancing TNBC cells drug resistance and proliferation. These data collectively demonstrate that MBD2c positively regulates mtDNA transcription, thus connecting epigenetic regulation by deacetylation with cancer cell metabolism, suggesting druggable targets to overcome resistance.
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Project description:Replication of mammalian mitochondrial DNA (mtDNA) is an essential process that requires high fidelity and control at multiple levels to ensure proper mitochondrial function. Mutations in the mitochondrial genome maintenance exonuclease 1 (MGME1) gene were recently reported in mitochondrial disease patients. Here, to study disease pathophysiology, we generated Mgme1 knockout mice and report that homozygous knockouts develop depletion and multiple deletions of mtDNA. The mtDNA replication stalling phenotypes vary dramatically in different tissues of Mgme1 knockout mice. Mice with MGME1 deficiency accumulate a long linear subgenomic mtDNA species, similar to the one found in mtDNA mutator mice, but do not develop progeria. This finding resolves a long-standing debate by showing that point mutations of mtDNA are the main cause of progeria in mtDNA mutator mice. We also propose a role for MGME1 in the regulation of replication and transcription termination at the end of the control region of mtDNA.
2018-07-11 | PXD009138 | Pride