Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

ChIP analysis trial of human TFB2M and POLRMT interaction with mtDNA

ABSTRACT: In many mammalian tissues and cells, two classes of mitochondrial DNA (mtDNA) replication intermediates have been observed. One involves leading-strand synthesis in the absence of synchronous lagging-strand synthesis (strand-asynchronous replication), and the other has properties of coupled leading- and lagging-strand synthesis (strand-coupled replication). While strand-asynchronous replication is primed by long RNA synthesized from a defined transcription initiation site, little is known about the commencement of strand-coupled replication. To investigate it, we attempted to abolish strand-asynchronous replication in cultured human cybrid cells by knocking out the components of the transcription initiation complexes, mitochondrial transcription factor B2 (TFB2M/mtTFB2) and mitochondrial RNA polymerase (POLRMT/mtRNAP). Surprisingly, removal of either protein resulted in the complete mtDNA loss, demonstrating for the first time that TFB2M and POLRMT are indispensable for human mtDNA maintenance. Moreover, the lack of TFB2M could not be compensated for by mitochondrial transcription factor B1 (TFB1M/mtTFB1). These findings indicate that TFB2M and POLRMT are crucial for the priming of not only strand-asynchronous but also strand-coupled replication, providing deeper insights into the molecular basis of strand-coupled replication initiation.

ORGANISM(S): Homo sapiens

PROVIDER: GSE161542 | GEO | 2021/11/21

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

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

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

2016-08-05 | GSE83368 | GEO

A second promoter on the human mitochondrial light strand

Project description:Human mitochondria contain multiple copies of a circular, double-stranded DNA genome which encode for unique protein components required for the synthesis of ATP. On each strand of mitochondrial DNA (mtDNA), polycistronic transcription is initiated from a dedicated promoter. Transcription from the light strand promoter can produce both near-genome length transcripts and short RNA primers for mtDNA replication. In this way, light strand gene expression and mitochondrial DNA replication are seen as coupled events, although there is no consensus as to how this is regulated. Here we report the discovery of a second light strand promoter (LSP2) in human mtDNA, located immediately upstream of the first gene on the light strand. LSP2 possesses nearly identical characteristics to canonical mitochondrial promoters. Our results challenge the prevailing model in mammals wherein regulation of transcription from the light strand promoter is a prerequisite for the synthesis of light strand genes, and suggests that light strand transcription can be decoupled from replication primer formation.

2022-08-29 | GSE176046 | GEO

Reduced cellular levels of DNA polymerase delta alter replication-fork dynamics and enzymology, and globally impair lagging-strand processing

Project description:DNA polymerase delta (Pol ∂) plays several essential roles in eukaryotic DNA replication and repair. At the replication fork, Pol ∂ is responsible for the synthesis and processing of the lagging strand; this role requires Pol ∂ to extend Okazaki fragment primers synthesized by Pol ⍺-primase, and to carry out strand-displacement synthesis coupled to nuclease cleavage during Okazaki fragment termination. Destabilizing mutations in human Pol ∂ subunits cause replication stress and syndromic immunodeficiency. Analogously, reduced levels of Pol ∂ in Saccharomyces cerevisiae lead to pervasive genome instability. Here, we analyze the how the depletion of Pol ∂ impacts replication initiation and elongation in vivo in S. cerevisiae. We determine that Pol ∂ depletion leads to a dependence on checkpoint signaling and recombination-mediated repair for cellular viability. By analyzing nascent lagging-strand products, we observe both a genome-wide change in the establishment and progression of replication forks and a global defect in Pol ∂-mediated Okazaki fragment processing. Additionally, we detect significant lagging-strand synthesis by the leading-strand polymerase (Pol ɛ) in late regions of the genome when Pol ∂ is depleted.

2019-12-13 | GSE141884 | GEO

The mitochondrial single-stranded DNA binding protein directs RNA primer formation for mtDNA replication

Project description:Single-stranded DNA (ssDNA) binding proteins protect regions of ssDNA formed during processes such as DNA replication and repair. We here devise a genetic screen and identify the mitochondrial ssDNA-binding protein (mtSSB) as a key regulator of mtDNA levels. In mitochondria, RNA synthesis from the light-strand promoter (LSP) is required for transcription as well as for generating the primers for initiation of mtDNA synthesis. We find that mtSSB is essential for mtDNA replication initiation, as transcription is strongly upregulated from the LSP in an mtSSB knockout mouse model, but cannot support the switch to replication. Using deep sequencing as well as biochemical reconstitution experiments, we find that mtSSB is also necessary to restrict transcription initiation and primer formation to specific promoters and origins of replication both in vitro and in vivo. Pathological mutations in human mtSSB cannot efficiently support primer maturation and origin specific initiation of mtDNA replication in vitro.

2021-05-19 | PXD021799 | Pride

RNase H1 directs origin-specific initiation of DNA replication in human mitochondria

Project description:Human mitochondrial DNA (mtDNA) replication is first initiated at the origin of H-strand replication. The initiation depends on RNA primers generated by transcription from an upstream promoter (LSP). Here we reconstitute this process in vitro using purified transcription and replication factors. The majority of all transcription events from LSP are prematurely terminated after 120 nucleotides, forming stable R-loops. These nascent R-loops cannot directly prime mtDNA synthesis, but must first be processed by RNase H1 to generate 3-ends that can be used by DNA polymerase to initiate DNA synthesis. Our findings are consistent with recent studies of a knockout mouse model, which demonstrated that RNase H1 is required for R-loop processing and mtDNA maintenance in vivo. Both R-loop formation and DNA replication initiation are stimulated by the mitochondrial single-stranded DNA binding protein. In an RNase H1 deficient patient cell line, the precise initiation of mtDNA replication is lost and DNA synthesis is initiated from multiple sites throughout the mitochondrial control region. In combination with previously published in vivo data, the findings presented here suggests a model, in which R-loop processing by RNase H1 directs origin-specific initiation of DNA replication in human mitochondria.

2018-10-26 | GSE103612 | GEO

The mitochondrial single-stranded DNA binding protein directs RNA primer formation for mtDNA replication [TruSeq]

2021-07-06 | GSE159569 | GEO

The mitochondrial single-stranded DNA binding protein directs RNA primer formation for mtDNA replication

Project description:Single-stranded DNA (ssDNA) binding proteins protect regions of ssDNA formed during processes such as DNA replication and repair. We here devise a genetic screen and identify the mitochondrial ssDNA-binding protein (mtSSB) as a key regulator of mtDNA levels. In mitochondria, RNA synthesis from the light-strand promoter (LSP) is required for transcription as well as for generating the primers for initiation of mtDNA synthesis. We find that mtSSB is essential for mtDNA replication initiation, as transcription is strongly upregulated from the LSP in a mtSSB knockout mouse model, but cannot support the switch to replication. Using deep sequencing as well as biochemical reconstitution experiments, we find that mtSSB is also necessary to restrict transcription initiation and primer formation to specific promoters and origins of replication both in vitro and in vivo. Pathological mutations in human mtSSB cannot efficiently support primer maturation and origin specific initiation of mtDNA replication in vitro.

2022-08-29 | GSE159481 | GEO

The mitochondrial single-stranded DNA binding protein directs RNA primer formation for mtDNA replication [sRNA]

2021-07-06 | GSE159570 | GEO

ChIP analysis trial of human TFB2M and POLRMT interaction with mtDNA

Project description:ChIP analysis trial of human TFB2M and POLRMT interaction with mtDNA

| PRJNA678680 | ENA