Project description:We introduce Affinity Distillation (AD), a method for extracting thermodynamic affinities de-novo from in-vivo immunoprecipitation experiments using deep learning. We show that neural networks modeling base-resolution in-vivo binding profiles of yeast and mammalian TFs can accurately predict energetic impacts of varying underlying DNA sequence on TF binding. Systematic comparisons between Affinity Distillation predictions and other predictive algorithms consistently show that Affinity Distillation more accurately predicts affinities across a wide range of TF structural classes and DNA sequences. Affinity Distillation relies on in-silico marginalization against many sequence backgrounds, resulting in a higher dynamic range and more accurate predictions than motif discovery algorithms. Moreover, we show that Affinity Distillation can learn differential paralog-specific affinities, thereby making it possible to more accurately reconstruct regulatory networks in cells.
Project description:We developed a new pipeline for accurate circRNA detection. We build a new atlas for characterizing circRNA in human, monkey, mouse, rat and drosophila brain. Our approach allows full annotation of circRNAs with fewer false positives and negatives than any individual pipeline or combination of them. Moreover, our approach is more sensitive than any individual pipeline and allows more accurate quantification and larger number of differentially expressed circRNAs.
Project description:The challenge of developing effective pharmacodynamic biomarkers for pre-clinical and clinical testing of FGFR signalling inhibition is significant. Assays that rely on the measurement of phospho-protein epitopes can be limited by the availability of effective antibody detection reagents. Transcript profiling enables accurate quantification of many biomarkers and a broader representation of pathway modulation. To identify dynamic transcript biomarkers of FGFR signalling inhibition by AZD4547, a potent inhibitor of FGF receptor 1, 2 and 3, a gene expression profiling study was performed in FGFR2 amplified drug sensitive tumour cell lines.
Project description:The pioneer transcription factor Pax7 contains two DNA binding domains (DBD), a paired and a homeo domain. Previous work on Pax7 and the related Pax3 showed that each DBD binds a cognate DNA sequence, thus defining two targets of binding and possibly modalities of action. Genomic targets of Pax7 pioneer action leading to chromatin opening are enriched for composite DNA target sites containing juxtaposed sites for both paired and homeo domains. The present work investigated the implication of the DBDs in pioneer action. We show that the composite sequence is a higher affinity binding site and that efficient binding to this site involves both DBDs of the same Pax7 molecule. This binding is not sensitive to cytosine methylation of the DNA sites consistent with pioneer action within nucleosomal heterochromatin. Introduction of single amino acid mutations in either paired or homeo domain that impair binding to cognate DNA sequences showed that both DBDs must be intact for pioneer action. In contrast, only the paired domain is required for low affinity binding of heterochromatin sites. Thus, Pax7 pioneer action on heterochromatin requires unique protein:DNA interactions that are more complex compared to its simpler DNA binding modalities at accessible enhancer target sites.
Project description:The pioneer transcription factor Pax7 contains two DNA binding domains (DBD), a paired and a homeo domain. Previous work on Pax7 and the related Pax3 showed that each DBD binds a cognate DNA sequence, thus defining two targets of binding and possibly modalities of action. Genomic targets of Pax7 pioneer action leading to chromatin opening are enriched for composite DNA target sites containing juxtaposed sites for both paired and homeo domains. The present work investigated the implication of the DBDs in pioneer action. We show that the composite sequence is a higher affinity binding site and that efficient binding to this site involves both DBDs of the same Pax7 molecule. This binding is not sensitive to cytosine methylation of the DNA sites consistent with pioneer action within nucleosomal heterochromatin. Introduction of single amino acid mutations in either paired or homeo domain that impair binding to cognate DNA sequences showed that both DBDs must be intact for pioneer action. In contrast, only the paired domain is required for low affinity binding of heterochromatin sites. Thus, Pax7 pioneer action on heterochromatin requires unique protein:DNA interactions that are more complex compared to its simpler DNA binding modalities at accessible enhancer target sites.
Project description:The pioneer transcription factor Pax7 contains two DNA binding domains (DBD), a paired and a homeo domain. Previous work on Pax7 and the related Pax3 showed that each DBD binds a cognate DNA sequence, thus defining two targets of binding and possibly modalities of action. Genomic targets of Pax7 pioneer action leading to chromatin opening are enriched for composite DNA target sites containing juxtaposed sites for both paired and homeo domains. The present work investigated the implication of the DBDs in pioneer action. We show that the composite sequence is a higher affinity binding site and that efficient binding to this site involves both DBDs of the same Pax7 molecule. This binding is not sensitive to cytosine methylation of the DNA sites consistent with pioneer action within nucleosomal heterochromatin. Introduction of single amino acid mutations in either paired or homeo domain that impair binding to cognate DNA sequences showed that both DBDs must be intact for pioneer action. In contrast, only the paired domain is required for low affinity binding of heterochromatin sites. Thus, Pax7 pioneer action on heterochromatin requires unique protein:DNA interactions that are more complex compared to its simpler DNA binding modalities at accessible enhancer target sites.
Project description:Most human transcription factors bind a small subset of potential genomic sites and often use different subsets in different cell types. To identify mechanisms that govern cell type-specific transcription factor binding, we used an integrative approach to study estrogen receptor α (ER). We found that ER exhibits two distinct modes of binding. Shared sites, bound in multiple cell types, are characterized by high affinity estrogen response elements (EREs), inaccessible chromatin and a lack of DNA methylation, while cell-specific sites are characterized by a lack of EREs, co-occurrence with other transcription factors and cell type-specific chromatin accessibility and DNA methylation. These observations enabled accurate quantitative models of ER binding that suggest tethering of ER to one-third of cell-specific sites. The distinct properties of cell-specific binding were also observed with glucocorticoid receptor and for ER in primary mouse tissues, representing an elegant genomic encoding scheme for generating cell type-specific gene regulation. ChIP-seq of transcription factors in mouse tissues
Project description:The histone variant H2A.Z is a genome-wide signature of nucleosomes proximal to eukaryotic regulatory DNA. While the multi-subunit SWR1 chromatin remodeling complex is known to catalyze ATP-dependent deposition of H2A.Z, the mechanism of recruitment to S. cerevisiae promoters has been unclear. A sensitive assay for competitive binding of di-nucleosome substrates revealed that SWR1 preferentially binds long nucleosome-free DNA adjoining core particles, allowing discrimination of gene promoters over gene bodies. We traced the critical DNA binding component of SWR1 to the conserved Swc2/YL1 subunit, whose activity is required for both SWR1 binding and H2A.Z incorporation in vivo. Histone acetylation by NuA4 enhances SWR1 binding, but the interaction with nucleosome-free DNA is the major determinant. ‘Hierarchical cooperation’ between high affinity DNA- and low affinity histone modification-binding factors may reconcile the large disparity in affinities for chromatin substrates, and unify classical control by DNA-binding factors with post-translational histone modifications and ATP-dependent nucleosome mobility.
Project description:The type II nuclear receptors (NRs) function as heterodimeric transcription factors with the retinoid X receptor (RXR) to regulate diverse biological processes in response to endogenous ligands and therapeutic drugs. DNA-binding specificity has been proposed as a primary mechanism for NR gene regulatory specificity. We use protein-binding microarrays (PBMs) to comprehensively analyze the DNA binding of 12 NR:RXRα heterodimers. We find more promiscuous NR-DNA binding than has been reported, challenging the view that NR binding specificity is defined by half-site spacing. We show that NRs bind DNA using two distinct modes, explaining widespread NR binding to half-sites in vivo. Finally, we show that the current models of NR specificity better reflect binding-site activity rather than binding-site affinity. Our rich dataset and revised NR binding models provide a framework for understanding NR regulatory specificity and will facilitate more accurate analyses of genomic datasets.
Project description:Due to the large size, complex splicing and wide dynamic range of eukaryotic transcriptomes, RNA sequencing samples the majority of expressed genes infrequently, resulting in sparse sequencing coverage that can hinder robust isoform assembly and quantification. Targeted RNA sequencing addresses this challenge by using oligonucleotide probes to capture selected genes or regions of interest for focused sequencing. This enhanced sequencing coverage confers sensitive gene discovery, robust transcript assembly and accurate gene quantification. Here we describe a detailed protocol for all stages of targeted RNA sequencing, from initial probe design considerations, capture of targeted genes, to final assembly and quantification of captured transcripts. Initial probe design and final analysis can take less than a day, while the central experimental capture stage requires ~7 days.