Project description:G-quadruplexes (G4s) are prevalent DNA structures that regulate transcription but also threaten genome stability. How G4 dynamics is controlled remains poorly understood. Here, we report that RNA transcripts govern G4 landscapes through coordinated ‘G-loop’ assembly and disassembly. G-loop assembly involves activation of the ATM and ATR kinases followed by homology-directed invasion of RNA opposite the G4 strand mediated by BRCA2 and RAD51. Disassembly of the G-loop resolves the G4 structure via DHX36-FANCJ-mediated G4 unwinding that triggers nucleolytic incision and subsequent hybrid strand renewal by DNA synthesis. Inhibition of G-loop disassembly causes global G4 and R-loop accumulation, leading to transcriptome dysregulation, replication stress, and genome instability. These findings establish an intricate G-loop assembly-disassembly mechanism that controls G4 landscapes and is essential for cellular homeostasis and survival.
Project description:G-quadruplexes (G4s) are prevalent DNA structures that regulate transcription but also threaten genome stability. How G4 dynamics is controlled remains poorly understood. Here, we report that RNA transcripts govern G4 landscapes through coordinated ‘G-loop’ assembly and disassembly. G-loop assembly involves activation of the ATM and ATR kinases followed by homology-directed invasion of RNA opposite the G4 strand mediated by BRCA2 and RAD51. Disassembly of the G-loop resolves the G4 structure via DHX36-FANCJ-mediated G4 unwinding that triggers nucleolytic incision and subsequent hybrid strand renewal by DNA synthesis. Inhibition of G-loop disassembly causes global G4 and R-loop accumulation, leading to transcriptome dysregulation, replication stress, and genome instability. These findings establish an intricate G-loop assembly-disassembly mechanism that controls G4 landscapes and is essential for cellular homeostasis and survival.
Project description:The R-loop is a common chromatin feature presented from prokaryotic to eukaryotic genomes and has been revealed to be involved in multiple cellular processes. Here, we developed a novel R-loop profiling technique, ULI-ssDRIP-seq, to decte global R-loops from a limited number of cells. Based on this method, we profiled the R-loop landscapes during parental-to-zygotic transition and early development regulatory in zebrafish, and revealed a series of important characters of R-loops.
Project description:The goal of this study was to compare the qualitative and quantitative differences in the presence of DNA:RNA hybrids (R-loops) between wild type and PrimPol knockout cell lines. Our initial genetic experiments on a reporter locus have showed a link between the formation of R-loop and non-B DNA motifs; we have therefore analysed the correlation between R-loop abundance and of sequences computationaly predicted to form triplex-DNA or G-quadruplex forming sequences, and whether this changes between the two cell lines.