Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Mitochondrial RNA polymerase overexpression enhances transcription initiation and exercise capacity without increasing mature mtRNA levels

ABSTRACT: POLRMT is the sole RNA polymerase in human mitochondria, where it generates primers for mitochondrial DNA (mtDNA) replication and transcribes the mtDNA to express genes encoding essential components of the oxidative phosphorylation (OXPHOS) system. Elevated POLRMT levels are found in several cancers and in mouse models with severe mitochondrial dysfunction. Here, we generated and characterized mice over-expressing Polrmt to investigate the physiological and molecular consequences of elevated POLRMT levels. Increasing POLRMT levels did not result in any pathological phenotype but led to increased exercise performance in male mice under stress conditions. Polrmt overexpression increased de novo transcription initiation, resulting in higher steady-state levels of the promoter-proximal L-strand transcript 7S RNA. Surprisingly, the abundance of mature mitochondrial RNAs was not affected by the elevated POLRMT levels. Furthermore, ubiquitous simultaneous overexpression of Polrmt and Lrpprc, which stabilizes mitochondrial messenger RNAs, did not increase steady-state levels of mitochondrial transcripts in the mouse. Our data show that POLRMT levels regulate transcription initiation, but additional regulatory steps downstream of transcription initiation and transcript stability limit OXPHOS biogenesis.

INSTRUMENT(S):

ORGANISM(S): Mus Musculus (mouse)

TISSUE(S): Heart, Skeletal Muscle, Liver

SUBMITTER: Ilian Atanassov

LAB HEAD: Inge Kühl

PROVIDER: PXD068527 | Pride | 2025-10-10

REPOSITORIES: Pride

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
	160506_QE_IA_IK_MM_01.raw	Raw
	160506_QE_IA_IK_MM_02.raw	Raw
	160506_QE_IA_IK_MM_03.raw	Raw
	160506_QE_IA_IK_MM_04.raw	Raw
	160506_QE_IA_IK_MM_05.raw	Raw

Items per page:

1 - 5 of 40

Similar Datasets

Activation of mtDNA transcription by mitochondrial RNA polymerase overexpression enhances stress-induced exercise capacity

Project description:POLRMT is the sole RNA polymerase in human mitochondria, where it generates primers for mitochondrial DNA (mtDNA) replication and transcribes the mtDNA to express genes encoding essential components of the oxidative phosphorylation (OXPHOS) system. Elevated POLRMT levels are found in several cancers and in mouse models with severe mitochondrial dysfunction. Here, we generated and characterized mice over-expressing Polrmt to investigate the physiological and molecular consequences of elevated POLRMT levels. Increasing POLRMT levels did not result in any pathological phenotype but led to increased exercise performance in male mice under stress conditions. Polrmt overexpression increased de novo transcription initiation, resulting in higher steady-state levels of the promoter-proximal L-strand transcript 7S RNA. Surprisingly, the abundance of mature mitochondrial RNAs was not affected by the elevated POLRMT levels. Furthermore, ubiquitous simultaneous overexpression of Polrmt and Lrpprc, which stabilizes mitochondrial messenger RNAs, did not increase steady-state levels of mitochondrial transcripts in the mouse. Our data show that POLRMT levels regulate transcription initiation, but additional regulatory steps downstream of transcription initiation and transcript stability limit OXPHOS biogenesis.

2025-09-11 | GSE307758 | GEO

Transcriptomic analysis by array of reactivation of dihydroorotate dehydrogenase by respiration restores tumor growth of mitochondrial DNA-depleted cancer cells.

Project description:Tumor cells without mitochondrial DNA (mtDNA) reconstitute oxidative phosphorylation (OXPHOS) by acquiring host mitochondria from stromal cells, but the reasons why functional respiration is crucial for tumorigenesis remain unclear. To address this issue, we used time-resolved analysis of the initial stages of tumor formation by cells devoid of mtDNA and genetic manipulations of components of OXPHOS. We show that pyrimidine biosynthesis, supported by respiration-linked dihydroorotate dehydrogenase (DHODH), is strictly required to overcome cell cycle arrest, while mitochondrial ATP generation is dispensable for tumorigenesis.

2018-10-01 | E-MTAB-6150 | biostudies-arrayexpress

High levels of TFAM repress in vivo transcription of mitochondrial DNA

Project description:Mammalian mitochondrial DNA (mtDNA) is coated with mitochondrial transcription factor A (TFAM) and compacted into nucleoids. TFAM is not only the main component of mitochondrial nucleoids but its levels can also control mtDNA copy number. Here we show that the TFAM-to-mtDNA ratio is critical for maintaining normal mtDNA expression in different tissues of the mouse. BAC transgenic mice with a 1.5-fold increase in TFAM protein levels maintain a normal TFAM-to-mtDNA ratio in different tissues and as a consequence mitochondrial gene expression, nucleoid distribution and whole animal metabolism are all unaltered. In contrast, mice expressing TFAM from the CAG promoter in the ROSA26 locus have 4.5-fold increase of TFAM protein levels in heart and skeletal muscle and develop pathology leading to early postnatal lethality. The TFAM-to-mtDNA ratio varies widely between tissues in these mice and is very high in skeletal muscle where it causes strong repression of mtDNA expression and deficient oxidative phosphorylation (OXPHOS) despite normal mtDNA levels. In heart, mtDNA copy number is increased leading to a near normal TFAM-to-mtDNA ratio and maintained OXPHOS capacity. In the liver, mtDNA expression is maintained despite increased TFAM levels and normal mtDNA levels. Here, tissue-specific induction of the LONP1 protease and mitochondrial RNA polymerase (POLRMT) expression counteracts the silencing effect of high TFAM levels. We conclude that the TFAM-to-mtDNA ratio has an important role in maintaining mtDNA expression in vivo. TFAM acts as a general repressor of mtDNA expression and this effect can be counterbalance by tissue-specific expression of regulatory factors.

2021-08-18 | PXD023050 | Pride

MitoExome Sequencing of Mitochondrial OXPHOS Diseases (MGH)

Project description: Human disorders of mitochondrial oxidative phosphorylation (OXPHOS) represent a devastating collection of inherited diseases. These disorders impact at least 1:5000 live births, and are characterized by multi-organ system involvement. They are characterized by remarkable locus heterogeneity, with mutations in the mtDNA as well as in over 77 nuclear genes identified to date. It is estimated that additional genes may be mutated in these disorders. To discover the genetic causes of mitochondrial OXPHOS diseases, we performed targeted, deep sequencing of the entire mitochondrial genome (mtDNA) and the coding exons of over 1000 nuclear genes encoding the mitochondrial proteome. We applied this 'MitoExome' sequencing to 124 unrelated patients with a wide range of OXPHOS disease presentations from the Massachusetts General Hospital Mitochondrial Disorders Clinic. The 2.3Mb targeted region was captured by hybrid selection and Illumina sequenced with paired 76bp reads. The total set of 1605 targeted nuclear genes included 1013 genes with strong evidence of mitochondrial localization from the MitoCarta database, 377 genes with weaker evidence of mitochondrial localization from the MitoP2 database and other sources, and 215 genes known to cause other inborn errors of metabolism. Approximately 88% of targeted bases were well-covered (>20X), with mean 200X coverage per targeted base.

| phs000339 | dbGaP

Effect of misregulation of mitochondrial 6mA on gene expression in C. elegans

Project description:In virtually all eukaryotes, the mitochondrial genome (mitochondrial DNA, mtDNA) encodes proteins necessary for oxidative phosphorylation (OXPHOS) and the RNA machinery required for their synthesis inside the mitochondria. Appropriate regulation of mtDNA copy number and expression is essential for ensuring the correct stoichiometric formation of OXPHOS complexes assembled from both nuclear- and mtDNA-encoded subunits. The mechanisms of mtDNA regulation are not completely understood but are essential to organismal viability and lifespan. Here, using multiple approaches, we identify the presence of N6-methylation of adenosine (6mA) on the mtDNA of diverse animal and plant species. Importantly, we also demonstrate that this modification is regulated in C. elegans by the DNA methyltransferase DAMT-1, and DNA demethylase ALKB-1, which localize to mitochondria. Misregulation of mtDNA 6mA through targeted overexpression of these enzymatic activities inappropriately alters mtDNA copy number and transcript levels, impairing OXPHOS function and producing increased oxidative stress, as well as a shortened lifespan. Compounding defects in mtDNA regulation, reductions in mtDNA 6mA methylation promote the propagation of a deleterious mitochondrial genome across generations. Together, these results reveal that mtDNA 6mA is highly conserved among eukaryotes and regulates lifespan by influencing mtDNA copy number, expression, and heritable mutation levels in vivo.

2024-08-11 | GSE272419 | GEO

POLRMT regulates the switch between replication-primer formation and gene expression of mammalian mtDNA

Project description:Mitochondria are vital in providing cellular energy via their oxidative phosphorylation system, which requires the coordinated expression of genes encoded by both the nuclear and mitochondrial genomes (mtDNA). Transcription of the circular mammalian mtDNA depends on a single mitochondrial RNA polymerase (POLRMT). Although the transcription initiation process is well understood, it remains highly controversial if POLRMT also serves as the primase for initiation of mtDNA replication. In the nucleus, the RNA polymerases needed for gene expression have no such role. Conditional knockout of Polrmt in heart results in severe mitochondrial dysfunction causing dilated cardiomyopathy in young mice. We further studied the molecular consequences of different expression levels of POLRMT and found that POLRMT is essential for primer synthesis to initiate mtDNA replication in vivo. Furthermore, transcription initiation for primer formation has priority over gene expression. Surprisingly, mitochondrial transcription factor A (TFAM) exists in an mtDNA-free pool in the Polrmt knockout mice. TFAM levels remain unchanged despite strong mtDNA depletion and TFAM is thus protected from degradation of the AAA+ Lon protease in absence of POLRMT. Lastly, mitochondrial transcription elongation factor (TEFM) can compensate for a partial depletion of POLRMT in heterozygous Polrmt knockout mice, indicating a direct regulatory role for this factor in transcription. In conclusion, we present here the first in vivo evidence that POLRMT has a key regulatory role in replication of mammalian mtDNA and is part of a mechanism that provides a switch between RNA primer formation for mtDNA replication and mtDNA expression. Isolated heart mitochondria from three control mice (L/L) and three Polrmt knockout mice (L/L, cre), aged 3-4 weeks, were sequenced and analyzed for differential expression.

2016-08-05 | E-GEOD-83368 | biostudies-arrayexpress

Mitochondrial DNA quantity Counteracts ROS damage in oocytes during female reproductive aging

Project description:We investigated the contentious role of mitochondrial reactive oxygen species (ROS) on mitochondrial DNA (mtDNA) quality and quantity in female reproductive aging. By conditionally knocking out the Sod2 gene in female mouse germline, we observed increased mitochondrial ROS and decreased oocyte quality, primarily due to impacts on OXPHOS complex II and mtDNA encoded mRNA levels. Interestingly, we found no increased mtDNA mutations, but alterations in mtDNA quantity, indicating the susceptibility of mtDNA to the mitochondrial ROS during reproductive aging. Notably, when we further decreased the basal level of mtDNA quantity by deactivating the mtSSB protein in Sod2 conditional knockout females, we observed an exacerbation of reproductive aging effects. This highlights the crucial role of mtDNA quantity in mitigating the impact of oxidative stress on fertility.

2024-09-09 | GSE251734 | GEO

Inhibition of mammalian mtDNA transcription in liver reprograms metabolism to reverse diet-induced obesity and hepatosteatosis

Project description:The oxidative phosphorylation (OXPHOS) system in mammalian mitochondria plays a key role in harvesting energy from different types of ingested nutrients1,2. Mitochondrial metabolism is very dynamic and can be reprogrammed to support both catabolic and anabolic reactions, depending on physiological demands or disease states3. Rewiring of mitochondrial metabolism is intricately linked to common metabolic diseases4–6 and is also necessary to promote tumor growth7–11. Here, we demonstrate that per oral treatment of mice with an inhibitor of mitochondrial transcription (IMT)11 leads to a profound inhibition of mtDNA expression in the liver, which markedly reduces complex I levels of the OXPHOS system, whereas the levels of electron transfer flavoprotein dehydrogenase (ETF-DH) and other dehydrogenases that feeds electrons into the ubiquinone (Q) pool remain unaltered or are increased. Deep pProteomics and non-targeted metabolomics analyses of liver reveal that IMT-treatment rewires the OXPHOS system to activates fatty acid oxidation in mice regardless of the diet. Remarkably, treatment of high fat diet (HFD)-fed mice with IMTs rapidly normalizes body weight, reverses hepatosteatosis and restores glucose tolerance. We thus propose a novel treatment principle of obesity and diabetes based on inhibition of mtDNA transcription to accomplish a rewiring of mitochondrial metabolism to favor fatty acid degradation.

2024-03-28 | PXD034771 | Pride

MITOCHONDRIAL ANTIOXIDANTS ABATE SARS-COV-2 LETHALITY IN MICE

Project description:SARS-CoV-2 infection inhibits mitochondrial oxidative phosphorylation (OXPHOS), elevates mitochondrial reactive oxygen species (mROS) which activates HIF-1α shifting metabolism toward glycolysis, and causes release of mtDNA which activates the innate immune system. To determine if mitochondrially targeted antioxidants could mitigate these viral effects, we combined in mice hACE2 with mitochondrially-targeted-catalase (mCAT) and showed that SARS-CoV-2 infected hACE2-mCAT mice had decreased weight loss; decreased circulating levels of mtDNA, IL-1β, and INF-β; and decreased lung HIF-1α and nucleocapsid protein levels. RNA-sequencing of infected lungs revealed that mCAT upregulated OXPHOS gene expression and downregulated glycolytic, innate immune, and HIF-1α-target gene expression. The mitochondrial antioxidant drug EUK8 had the same effect as mCAT potentially providing a pharmacological therapy for COVID-19 which is not subject to viral mutational resistance.

2024-07-31 | GSE246312 | GEO

An inherited mtDNA mutation remodels inflammatory cytokine responses in macrophages and in vivo

Project description:Impaired mitochondrial bioenergetics in macrophages can drive hyperinflammatory cytokine responses1–6, but whether this may also be caused by inherited mtDNA mutations is unknown. Here, we address this question using a multi-omic approach that integrates super-resolution imaging and metabolic analyses to profile macrophages from a mouse model of mitochondrial disease arising from a heteroplasmic mutation (m.5019A>G) in the mitochondrial tRNA for alanine7. These m.5019A>G macrophages exhibit defects in respiratory chain complexes and oxidative phosphorylation (OxPhos) due to decreased intra-mitochondrial translation. To adapt to this metabolic stress, mitochondrial fusion, reductive glutamine metabolism, and aerobic glycolysis are all increased. Upon inflammatory activation, type I interferon (IFN-I) release is enhanced, while the production of pro-inflammatory cytokines and oxylipins are restrained in m.5019A>G macrophages. Finally, an in vivo endotoxemia model using m.5019A>G mice reveal elevated IFN-I levels and sickness behaviour. In conclusion, our study identifies an unexpected imbalance in innate immune signalling in response to a pathogenic mtDNA mutation, with important implications for the progression of pathology in patients with mtDNA diseases

2025-09-17 | PXD060284 | Pride

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data