Project description:The enormous variety of different RNAs are transcribed from eukaryotic genome. Some RNAs, particular long non-coding RNAs (lncRNAs), enrich on chromatin via transcribed RNAs to retain at their transcription site (Cis-acting RNAs) and recruited to different genomic regions (Trans-acting RNAs), which play significant roles in regulating gene transcription, epigenomic modifications and mediating chromatin states. Here, we developed TaDRIM-Seq (Targeted DNA-associated RNA and RNA-RNA Interactions Mapping by Sequencing) method to capture RNA-DNA on specific protein region and RNA-RNA spatial interactions in nuclei. We performed TaDRIM-Seq of antibodies H3, H3K9ac and H3K27me3 in rice and H3K4me3 and CTCF in human K562 cells, to identify chromatin-interacting RNAs and RNA-RNA interactions.
Project description:The enormous variety of different RNAs are transcribed from eukaryotic genome. Some RNAs, particular long non-coding RNAs (lncRNAs), enrich on chromatin via transcribed RNAs to retain at their transcription site (Cis-acting RNAs) and recruited to different genomic regions (Trans-acting RNAs), which play significant roles in regulating gene transcription, epigenomic modifications and mediating chromatin states. Here, we developed TaDRIM-Seq (Targeted DNA-associated RNA and RNA-RNA Interactions Mapping by Sequencing) method to capture RNA-DNA on specific protein region and RNA-RNA spatial interactions in nuclei. We performed TaDRIM-Seq of antibodies H3, H3K9ac and H3K27me3 in rice and H3K4me3 and CTCF in human K562 cells, to identify chromatin-interacting RNAs and RNA-RNA interactions.
Project description:The vast landscape of RNA-protein interactions at the heart of post-transcriptional regulation remains largely unexplored. Indeed it is likely that, even in yeast, a substantial fraction of the regulatory RNA-binding proteins (RBPs) remain to be discovered. Systematic experimental methods can play a key role in discovering these RBPs - most of the known yeast RBPs lack RNA-binding domains that might enable this activity to be predicted. We describe here a new proteome-wide approach to identify RNA-protein interactions based on in vitro binding of RNA samples to yeast protein microarrays that represent over 80% of the yeast proteome. We used this procedure to screen for novel RBPs and RNA-protein interactions. A complementary mass spectrometry technique also identified proteins that associate with yeast mRNAs. Both the protein microarray and mass spectrometry methods successfully identify previously annotated RBPs, suggesting that other proteins identified in these assays might be novel RBPs. Of 35 putative novel RBPs identified by either or both of these methods, 12, including 75% of the eight most highly-ranked candidates, reproducibly associated with specific cellular RNAs. Surprisingly, most of the 12 newly discovered RBPs were enzymes. Functional characteristics of the RNA targets of some of the novel RBPs suggest coordinated post-transcriptional regulation of subunits of protein complexes and a possible link between mRNA trafficking and vesicle transport. Our results suggest that many more RBPs still remain to be identified and provide a set of candidates for further investigation.
Project description:Mapping of nucleosomes, the basic DNA packaging unit in eukaryotes, is fundamental for understanding genome regulation as nucleosomes modulate DNA access by their positioning along the genome. A cell population nucleosome map requires two observables: nucleosome positions along the DNA (“Where?”) and nucleosome occupancies across the population (“In how many cells?”). All available genome-wide nucleosome mapping techniques are yield methods as they score either nucleosomal (e.g., MNase-seq, chemical cleavage-seq) or non-nucleosomal (e.g., ATAC-seq) DNA but lose track of the total DNA population for each genomic region. Therefore, they only provide nucleosome positions and maybe compare relative occupancies between positions but cannot measure absolute nucleosome occupancy, which is the fraction of all DNA molecules occupied at a given position and time by a nucleosome. Here, we established two orthogonal and thereby crossvalidating approaches to measure absolute nucleosome occupancy across the Saccharomyces cerevisiae genome via restriction enzymes and DNA methyltransferases. The resulting high-resolution (9 bp) map shows uniform absolute occupancies. Most nucleosome positions are occupied in most cells: 97% of all nucleosomes called by chemical cleavage-seq have a mean absolute occupancy of 90 ± 6% (± SD). Depending on nucleosome position calling procedures, there are 57-60,000 nucleosomes per yeast cell. The few low absolute occupancy nucleosomes do not correlate with highly transcribed gene bodies, but with increased presence of the nucleosome-evicting RSC chromatin remodeling complex there and are enriched upstream of highly transcribed or regulated genes. Our work provides a quantitative method and reference frame in absolute terms for future chromatin studies.
Project description:Mapping of nucleosomes, the basic DNA packaging unit in eukaryotes, is fundamental for understanding genome regulation as nucleosomes modulate DNA access by their positioning along the genome. A cell population nucleosome map requires two observables: nucleosome positions along the DNA (“Where?”) and nucleosome occupancies across the population (“In how many cells?”). All available genome-wide nucleosome mapping techniques are yield methods as they score either nucleosomal (e.g., MNase-seq, chemical cleavage-seq) or non-nucleosomal (e.g., ATAC-seq) DNA but lose track of the total DNA population for each genomic region. Therefore, they only provide nucleosome positions and maybe compare relative occupancies between positions but cannot measure absolute nucleosome occupancy, which is the fraction of all DNA molecules occupied at a given position and time by a nucleosome. Here, we established two orthogonal and thereby crossvalidating approaches to measure absolute nucleosome occupancy across the Saccharomyces cerevisiae genome via restriction enzymes and DNA methyltransferases. The resulting high-resolution (9 bp) map shows uniform absolute occupancies. Most nucleosome positions are occupied in most cells: 97% of all nucleosomes called by chemical cleavage-seq have a mean absolute occupancy of 90 ± 6% (± SD). Depending on nucleosome position calling procedures, there are 57-60,000 nucleosomes per yeast cell. The few low absolute occupancy nucleosomes do not correlate with highly transcribed gene bodies, but with increased presence of the nucleosome-evicting RSC chromatin remodeling complex there and are enriched upstream of highly transcribed or regulated genes. Our work provides a quantitative method and reference frame in absolute terms for future chromatin studies.
Project description:Mapping of nucleosomes, the basic DNA packaging unit in eukaryotes, is fundamental for understanding genome regulation as nucleosomes modulate DNA access by their positioning along the genome. A cell population nucleosome map requires two observables: nucleosome positions along the DNA (“Where?”) and nucleosome occupancies across the population (“In how many cells?”). All available genome-wide nucleosome mapping techniques are yield methods as they score either nucleosomal (e.g., MNase-seq, chemical cleavage-seq) or non-nucleosomal (e.g., ATAC-seq) DNA but lose track of the total DNA population for each genomic region. Therefore, they only provide nucleosome positions and maybe compare relative occupancies between positions but cannot measure absolute nucleosome occupancy, which is the fraction of all DNA molecules occupied at a given position and time by a nucleosome. Here, we established two orthogonal and thereby crossvalidating approaches to measure absolute nucleosome occupancy across the Saccharomyces cerevisiae genome via restriction enzymes and DNA methyltransferases. The resulting high-resolution (9 bp) map shows uniform absolute occupancies. Most nucleosome positions are occupied in most cells: 97% of all nucleosomes called by chemical cleavage-seq have a mean absolute occupancy of 90 ± 6% (± SD). Depending on nucleosome position calling procedures, there are 57-60,000 nucleosomes per yeast cell. The few low absolute occupancy nucleosomes do not correlate with highly transcribed gene bodies, but with increased presence of the nucleosome-evicting RSC chromatin remodeling complex there and are enriched upstream of highly transcribed or regulated genes. Our work provides a quantitative method and reference frame in absolute terms for future chromatin studies.