Transcriptional repression by a secondary DNA binding surface of DNA topoisomerase I safeguards against hypertranscription
Ontology highlight
ABSTRACT:
PROVIDER: PRJNA854061 | ENA |
REPOSITORIES: ENA
Dataset's files
| Action | DRS | |||
|---|---|---|---|---|
| SRR19900800_1.fastq.gz | Fastqsanger.gz | |||
| SRR19900800_2.fastq.gz | Fastqsanger.gz | |||
| SRR19900801.fastq.gz | Fastqsanger.gz | |||
| SRR19900802.fastq.gz | Fastqsanger.gz | |||
| SRR19900803.fastq.gz | Fastqsanger.gz |
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Project description:Regulation of global transcription output is important for normal development and disease but only few regulators of the process are known. Here, we describe DNA topoisomerase I (TOP1) as a novel regulator where it exerts transcriptional repression to prevent transcription overdrive. This function requires a conserved secondary DNA binding surface that is distinct from its catalytic pocket.
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Project description:Regulation of global transcription output is important for normal development and disease, but little is known about the mechanisms involved. DNA topoisomerase I (TOP1) is an enzyme well-known for its role in relieving DNA supercoils for enabling transcription. Here, we report a non-enzymatic function of TOP1 that downregulates RNA synthesis. This function is dependent on specific DNA-interacting residues located on a conserved protein surface. A loss-of-function knock-in mutation on this surface, R548Q, is sufficient to cause hypertranscription and alter differentiation outcomes in mouse embryonic stem cells (mESCs). Hypertranscription in mESCs is accompanied by reduced TOP1 chromatin binding and change in genomic supercoiling. Notably, the mutation does not impact TOP1 enzymatic activity; rather, it diminishes TOP1-DNA binding and formation of compact protein-DNA structures. Thus, TOP1 exhibits opposing influences on transcription through distinct activities which are likely to be coordinated. This highlights TOP1 as a safeguard of appropriate total transcription levels in cells.
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Project description:Stem and progenitor cells undergo a global elevation of nascent transcription, or hypertranscription, during key developmental transitions involving rapid cell proliferation. The chromatin remodeler Chd1 binds to RNA Pol I and II genes and is required for hypertranscription in embryonic stem (ES) cells in vitro and the early post-implantation epiblast in vivo. Biochemically, Chd1 has been shown to facilitate transcription at least in part by removing nucleosomal barriers to elongation, but its mechanism of action in stem cells remains poorly understood. Here we report a novel role for Chd1 in the repair of promoter-proximal endogenous double-stranded DNA breaks (DSBs) in ES cells. An unbiased proteomics approach revealed that Chd1 interacts with several DNA repair factors including ATM, Parp1, Kap1 and Topoisomerase 2. We show that wild-type ES cells display high levels of phosphorylated H2AX and Kap1 at chromatin, notably at rDNA in the nucleolus, in a Chd1-dependent manner. Loss of Chd1 leads to an extensive accumulation of DSBs at Chd1 target Pol II genes and rDNA. Genes prone to DNA breaks in Chd1-null ES cells tend to be longer genes with GC-rich promoters, a more labile nucleosomal structure and roles in chromatin organization, transcription and signaling. These results reveal a vulnerability of hypertranscribing stem cells to endogenous DNA breaks, with important implications for developmental and cancer biology.
2021-06-14 | PXD024604 | Pride
Project description:Stem and progenitor cells undergo a global elevation of nascent transcription, or hypertranscription, during key developmental transitions involving rapid cell proliferation. The chromatin remodeler Chd1 binds to genes transcribed by RNA Pol I and II and is required for hypertranscription in embryonic stem (ES) cells in vitro and the early post-implantation epiblast in vivo. Biochemically, Chd1 has been shown to facilitate transcription at least in part by removing nucleosomal barriers to elongation, but its mechanism of action in stem cells remains poorly understood. Here we report a novel role for Chd1 in the repair of promoter-proximal endogenous double-stranded DNA breaks (DSBs) in ES cells. An unbiased proteomics approach revealed that Chd1 interacts with several DNA repair factors including ATM, Parp1, Kap1 and Topoisomerase 2β. We show that wild-type ES cells display high levels of phosphorylated H2AX and Kap1 at chromatin, notably at rDNA in the nucleolus, in a Chd1-dependent manner. Loss of Chd1 leads to an extensive accumulation of DSBs at Chd1-bound Pol II-transcribed genes and rDNA. Genes prone to DNA breaks in Chd1-null ES cells tend to be longer genes with GC-rich promoters, a more labile nucleosomal structure and roles in chromatin organization, transcription and signaling. These results reveal a vulnerability of hypertranscribing stem cells to endogenous DNA breaks, with important implications for developmental and cancer biology.
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Project description:The cancer target enyzme topoisomerase 1 transiently cleaves one strand of chromosomal DNA to relax accumulated strain that can prevent transcription, replication or chromatin assembly. The topoisomerase 1 poison camptothecin and its synthetic analogs are widely used chemotherapeutics that act by trapping the enzyme on DNA in a ‘covalent complex’, resulting in persistent DNA damage and cell death. The prevailing model, interfacial inhibition, contends that the covalent complex is trapped by drug binding alone. In contrast, here we show that camptothecins produce extensive oxidative stress and that topoisomerase 1 is reactive with electrophilic second messengers of oxidative damage. We show that blocking oxidative stress in cells inhibits covalent complex formation by camptothecin, while electrophiles such as 4-hydroxynonenal are able to induce covalent complex formation in cells on their own. Towards mechanism of action, we show that 4-hydroxynonenal electrophilically modifies a cysteine within the DNA-binding active site of human topoisomerase 1. Taken together, our results suggest a mechanism in which oxidative stress mediates the effects of many topoisomerase 1 poisons, and suggest that this critical DNA-regulating enzyme may have a dual role as a sensor of cellular redox stress, linking oxidative stress to DNA damage response in cancer cells.
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Project description:Hyperproliferation driven by the protooncogene MYC has been presumed to elicit a chain of event that leads to DNA damage and activates the tumor suppressor p53 response. This DNA damage has been presumed to derive from hypertranscription and overreplication. Here, we report that MYC-topoisome (MYC/Topoisomerase 1/Topoisomerase 2) formation is genotoxic within minutes of its formation. Topoisome mediated damage activates pATM and p53, that in turn shuts off MYC and dissociates the topoisome in vitro and in vivo. To manage topological and torsional stress generated at its targets, p53 assembles its own topoisome. Because topoisomerase activity is intrinsically DNA-damaging, the p53-topoisome creates initial burst of DNA damage but, because p53 (unlike MYC) upregulates the DNA damage response and activates TDP1 and TDP2, this damage is quickly suppressed. The novel coupling of TOP1 and TOP2 sponsored by p53, creates a tool to support the expression of p53 targets while braking MYC-accelerated cell growth.
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Project description:The Hippo pathway controls the activity of YAP/TAZ transcriptional coactivators through a kinase cascade. Despite the critical role of this pathway in tissue growth and tumorigenesis, it is not fully understood how YAP/TAZ–mediated transcription drives proliferation. By analyzing the effects of inactivating LATS1/2 kinases, the direct upstream inhibitors of YAP/TAZ, on mouse brain development and applying cell-number–normalized transcriptome analysis, we discovered that YAP/TAZ activation causes a global increase in transcription activity, known as hypertranscription, and upregulates many genes associated with increased biosynthetic capacity and proliferation. In contrast, conventional read-depth–normalized RNA-sequencing analysis failed to detect the scope of the transcriptome shift and missed most relevant gene ontologies. Hypertranscription in neural progenitors inhibits differentiation and triggers DNA replication stress, DNA damage, and p53 activation, resulting in massive apoptosis. Our findings reveal the remarkable impact of YAP/TAZ activation on global transcription activity and have important implications for understanding YAP/TAZ function
2019-02-19 | GSE119935 | GEO
Project description:Here we dissect the transcriptional response in S. cerevisiae cells lacking DNA topoisomerases. We use microarray technology coupled with a functional genomics approach and demonstrate intimate connections between topoisomerase dependency, promoter chromatin architecture and gene transcription. Our findings suggest that DNA topoisomerases I and II play a role for transcription initiation. We observe a genome wide reduction in mRNA levels and identify a distinct functional subset of the genome with particular requirements for topoisomerases. These genes are characterized by high transcriptional plasticity, they are chromatin regulated and distinguished by having an enrichment of a nucleosome at a critical position in the promoter region, suggesting that topoisomerases influence transcription initiation by affecting promoter chromatin structure. In further support of a role of topoisomerases for initiation, we demonstrate that genome wide topoisomerase dependency reflects transcriptional activity but not transcriptional length. We exemplify the importance of topoisomerases for initiation of chromatin-regulated genes by showing that the enzymes are essential although redundant for PHO5 induction and are necessary for a step required for promoter nucleosome removal. W303 versus top1Î?, top2ts and top1Î?top2ts. 3 biological replicates for each mutant versus wildtype counterpart amounting to 12 microarrays.
2012-07-31 | E-GEOD-22809 | biostudies-arrayexpress