Project description:The misrepair of DNA double-strand breaks in close spatial proximity within the nucleus can result in chromosomal rearrangements that are important in the pathogenesis of hematopoietic and solid malignancies. It is unknown why certain epigenetic states, such as those found in stem or progenitor cells, appear to facilitate neoplastic transformation. Here we show that altering the transcriptional state of human astrocytes alters patterns of DNA damage repair from ionizing radiation at a gene locus-specific and genome-wide level. Astrocytes induced into a reactive state exhibited increased DNA repair, compared to non-reactive cells, in actively transcribed chromatin domains after irradiation. In mapping these sites of repair, we identified misrepair events and repair hotspots that were unique to each state. The precise characterization of genomic regions susceptible to mutation in specific epigenetic transcriptional states provides new opportunities for addressing clonal evolution in solid cancers, particularly those where double-strand break induction is a cornerstone of management. Primary astrocyte cells were cultured to confluency and went through a linear monolyer scratch or no scratch.
Project description:The misrepair of DNA double-strand breaks in close spatial proximity within the nucleus can result in chromosomal rearrangements that are important in the pathogenesis of hematopoietic and solid malignancies. It is unknown why certain epigenetic states, such as those found in stem or progenitor cells, appear to facilitate neoplastic transformation. Here we show that altering the transcriptional state of human astrocytes alters patterns of DNA damage repair from ionizing radiation at a gene locus-specific and genome-wide level. Astrocytes induced into a reactive state exhibited increased DNA repair, compared to non-reactive cells, in actively transcribed chromatin domains after irradiation. In mapping these sites of repair, we identified misrepair events and repair hotspots that were unique to each state. The precise characterization of genomic regions susceptible to mutation in specific epigenetic transcriptional states provides new opportunities for addressing clonal evolution in solid cancers, particularly those where double-strand break induction is a cornerstone of management.
Project description:In the bacterium Escherichia coli, RecG directs DNA synthesis during the repair of DNA double-strand breaks by homologous recombination. Examination of RecA binding during double-strand break repair in Escherichia coli in the presence and absence of RecG protein
Project description:HELB is a human helicase involved in initiation of DNA replication, the replication stress response, and regulation of double-strand DNA break repair. rs75770066 is a low-frequency single-nucleotide polymorphism (SNP) in the HELB gene that affects age at natural menopause. rs75770066 results in a D506G substitution in a HELB specific insertion in the 1A domain of the helicase that contains amino acids known to interact with RPA. We found that this amino acid change has no effect on the enzymatic activity of HELB but dramatically impairs the cellular function of HELB. D506G HELB exhibits impaired interaction with RPA, which likely results in the effects of rs75770066 as this reduces recruitment of HELB to sites of DNA damage. Reduced recruitment of D506G-HELB to double-strand DNA breaks and the concomitant increase in homologous recombination likely alters the levels of meiotic recombination, which affects the viability of gametes. Because menopause occurs when oocyte levels drop below a minimum threshold, altered repair of meiotic double-stranded DNA breaks has the potential to directly affect the age at natural menopause.
2024-11-12 | MSV000096390 | MassIVE
Project description:Repair-seq screens of double-strand break repair
Project description:Recent observations show that the single-cell response of p53 to ionizing radiation (IR) is “digital” in that it is the number of oscillations rather than the amplitude of p53 that shows dependence on the radiation dose. We present a model of this phenomenon. In our model, double-strand break (DSB) sites induced by IR interact with a limiting pool of DNA repair proteins, forming DSB–protein complexes at DNA damage foci. The persisting complexes are sensed by ataxia telangiectasia mutated (ATM), a protein kinase that activates p53 once it is phosphorylated by DNA damage. The ATM-sensing module switches on or off the downstream p53 oscillator, consisting of a feedback loop formed by p53 and its negative regulator, Mdm2. In agreement with experiments, our simulations show that by assuming stochasticity in the initial number of DSBs and the DNA repair process, p53 and Mdm2 exhibit a coordinated oscillatory dynamics upon IR stimulation in single cells, with a stochastic number of oscillations whose mean increases with IR dose. The damped oscillations previously observed in cell populations can be explained as the aggregate behavior of single cell
Project description:In the bacterium Escherichia coli, RecBCD coordinates repair of two ends at a DNA double-strand break, preventing aberrant chromosome amplification
Project description:The Mre11-Rad50-Nbs1 (MRN) complex recognizes and processes DNA double-strand breaks for homologous recombination by performing short-range removal of 5ʹ strands. Endonucleolytic processing by MRN requires a stably bound protein at the break site—a role we postulate is played by DNA-dependent protein kinase (DNA-PK) in mammals. Here we interrogate sites of MRN-dependent processing by identifying sites of CtIP association and by sequencing DNA- PK-bound DNA fragments that are products of MRN cleavage. These intermediates are generated most efficiently when DNA-PK is catalytically blocked, yielding products within 200 bp of the break site, whereas DNA-PK products in the absence of kinase inhibition show greater dispersal. Use of light-activated Cas9 to induce breaks facilitates temporal resolution of DNA- PK and Mre11 binding, showing that both complexes bind to DNA ends before release of DNA- PK-bound products. These results support a sequential model of double-strand break repair involving collaborative interactions between homologous and non-homologous repair complexes.
Project description:The TEA domain family members 1-4 (TEADs) are major transcription factors for YAP/TAZ transcription activators in the Hippo pathway, regulating many biological processes, including development, tissue homeostasis, and tumorigenesis through target genes. Their amplification/upregulation correlates with poor prognosis in cancer patients. Although the Hippo pathway continues to be elucidated, it is clear that TEAD largely exerts its actions via transcriptional regulation. Here, we uncover an unexpected role for TEADs in the DNA damage response. Using comparative mass spectrometry, we demonstrate that TEADs interact with several DNA repair proteins. We further show that TEADs form DNA damage-induced nuclear foci that co-localize with DNA damage markers. We also found that TEADs are required for resistance to DNA damage, maintaining genome stability, and resolution of double strand break repair that is independent from the Hippo pathway and its transcriptional role. Our results establish a new role for TEADs in DNA repair and therefore, highlight a critical consideration in therapeutically targeting the Hippo pathway.