Similar Datasets
Project description:To dissect the molecular mechanisms of the transcription factor FOXA2 accessing nucleosomal targets and controlling cell fates, we combined live-cell single-molecule imaging, genome editing, chromatin binding, chromatin accessibility, and RNA sequence analysis. Using the hESC differentiation cellular system to anterior primitive streak (APS) and definitive endoderm (DE), we demonstrated by RNA-seq that FOXA2 is a lineage-determining transcription factor for DE formation and that its intrinsically disordered C-terminal domain (CTD) is essential for its normal function. Through ChIP-seq and ATAC-seq at multiple time points of exogenous expression, we also showed that the CTD is required for FOXA2 effectively accessing targets in closed chromatin and altering chromatin accessibility. Together with the single-molecule kinetics captured by fluorescence microscopy, this study uncovers new mechanistic insights on the activity of lineage-determining transcription factors in engaging chromatin and accessing nucleosomal targets.
2024-04-29 | GSE203649 | GEO
Project description:To dissect the molecular mechanisms of the transcription factor FOXA2 accessing nucleosomal targets and controlling cell fates, we combined live-cell single-molecule imaging, genome editing, chromatin binding, chromatin accessibility, and RNA sequence analysis. Using the hESC differentiation cellular system to anterior primitive streak (APS) and definitive endoderm (DE), we demonstrated by RNA-seq that FOXA2 is a lineage-determining transcription factor for DE formation and that its intrinsically disordered C-terminal domain (CTD) is essential for its normal function. Through ChIP-seq and ATAC-seq at multiple time points of exogenous expression, we also showed that the CTD is required for FOXA2 effectively accessing targets in closed chromatin and altering chromatin accessibility. Together with the single-molecule kinetics captured by fluorescence microscopy, this study uncovers new mechanistic insights on the activity of lineage-determining transcription factors in engaging chromatin and accessing nucleosomal targets.
2024-04-29 | GSE203644 | GEO
Project description:To dissect the molecular mechanisms of the transcription factor FOXA2 accessing nucleosomal targets and controlling cell fates, we combined live-cell single-molecule imaging, genome editing, chromatin binding, chromatin accessibility, and RNA sequence analysis. Using the hESC differentiation cellular system to anterior primitive streak (APS) and definitive endoderm (DE), we demonstrated by RNA-seq that FOXA2 is a lineage-determining transcription factor for DE formation and that its intrinsically disordered C-terminal domain (CTD) is essential for its normal function. Through ChIP-seq and ATAC-seq at multiple time points of exogenous expression, we also showed that the CTD is required for FOXA2 effectively accessing targets in closed chromatin and altering chromatin accessibility. Together with the single-molecule kinetics captured by fluorescence microscopy, this study uncovers new mechanistic insights on the activity of lineage-determining transcription factors in engaging chromatin and accessing nucleosomal targets.
2024-04-29 | GSE203640 | GEO
Project description:The androgen receptor (AR) is a critical therapeutic target in prostate cancer that responds to antagonists in primary disease, but inevitably becomes reactivated, signaling onset of the lethal castration-resistant prostate cancer (CRPC) stage. Epigenomic investigation of the chromatin environment and interacting partners required for AR transcriptional activity has uncovered three pioneer factors that open up chromatin and facilitate AR-driven transcriptional programs. FOXA1, HOXB13, and GATA2 are required for normal AR transcription in prostate epithelial development and for oncogenic AR transcription during prostate carcinogenesis. AR signaling is dependent upon these three pioneer factors both before and after the clinical transition from treatable androgen-dependent disease to untreatable CRPC. Agents targeting their respective DNA binding or downstream chromatin-remodeling events have shown promise in preclinical studies of CRPC. AR-independent functions of FOXA1, HOXB13, and GATA2 are emerging as well. While all three pioneer factors exert effects that promote carcinogenesis, some of their functions may inhibit certain stages of prostate cancer progression. In all, these pioneer factors represent some of the most promising potential therapeutic targets to emerge thus far from the study of the prostate cancer epigenome.
| S-EPMC7299826 | biostudies-literature
Project description:Pioneer transcription factors (TFs) access silent chromatin and initiate cell-fate changes, using diverse types of DNA binding domains (DBDs). FoxA, the paradigm pioneer TF, has a winged helix DBD that resembles linker histone and thereby binds its target sites on nucleosomes and in compacted chromatin. Herein, we compare the nucleosome and chromatin targeting activities of Oct4 (POU DBD), Sox2 (HMG box DBD), Klf4 (zinc finger DBD), and c-Myc (bHLH DBD), which together reprogram somatic cells to pluripotency. Purified Oct4, Sox2, and Klf4 proteins can bind nucleosomes in vitro, and in vivo they preferentially target silent sites enriched for nucleosomes. Pioneer activity relates simply to the ability of a given DBD to target partial motifs displayed on the nucleosome surface. Such partial motif recognition can occur by coordinate binding between factors. Our findings provide insight into how pioneer factors can target naive chromatin sites.
| S-EPMC4409934 | biostudies-literature
Project description:Biomolecular condensation constitutes an emerging mechanism for transcriptional regulation. Recent studies suggest that the co-condensation between transcription factors (TFs) and DNA can generate mechanical forces driving genome rearrangements. However, the reported forces generated by protein-DNA co-condensation are typically below one piconewton (pN), questioning its physiological significance. Moreover, the force-generating capacity of these condensates in the chromatin context remains unknown. Here, we show that Sox2, a nucleosome-binding pioneer TF, forms co-condensates with DNA and generates forces up to 7 pN, exerting considerable mechanical tension on DNA strands. We find that the disordered domains of Sox2 are required for maximum force generation but not for condensate formation. Furthermore, we show that nucleosomes dramatically attenuate the mechanical stress exerted by Sox2 by sequestering it from coalescing on bare DNA. Our findings reveal that TF-mediated DNA condensation can exert significant mechanical stress on the genome which can nonetheless be attenuated by the chromatin architecture.
| S-EPMC9271091 | biostudies-literature
Project description:Unlike most transcription factors (TF), pioneer TFs have a specialized role in binding closed regions of chromatin and initiating the subsequent opening of these regions. Thus, pioneer TFs are key factors in gene regulation with critical roles in developmental transitions, including organ biogenesis, tissue development, and cellular differentiation. These developmental events involve some major reprogramming of gene expression patterns, specifically the opening and closing of distinct chromatin regions. Here, we discuss how pioneer TFs are identified using biochemical and genome-wide techniques. What is known about pioneer TFs from animals and plants is reviewed, with a focus on the strategies used by pioneer factors in different organisms. Finally, the different molecular mechanisms pioneer factors used are discussed, highlighting the roles that tertiary and quaternary structures play in nucleosome-compatible DNA-binding.
| S-EPMC6222629 | biostudies-literature
Project description:Nucleosomes restrict the occupancy of most transcription factors (TF) by reducing binding and accelerating dissociation, while a small group of TFs have high affinities to nucleosome-embedded sites and facilitate nucleosome displacement. To understand this process mechanistically, we investigated two Saccharomyces cerevisiae TFs, Reb1 and Cbf1. We show that these factors bind to their sites within nucleosomes with similar binding affinities as to naked DNA, trapping a partially unwrapped nucleosome without histone eviction. Both the binding and dissociation rates of Reb1 and Cbf1 are significantly slower at the nucleosomal sites relative to those for naked DNA, demonstrating that the high affinities are achieved by increasing the dwell time on nucleosomes in order to compensate for reduced binding. Reb1 also shows slow migration rate in the yeast nuclei. These properties are similar to those of human pioneer factors (PFs), suggesting that the mechanism of nucleosome targeting is conserved from yeast to humans.
| S-EPMC6449090 | biostudies-literature
Project description:During eukaryotic transcription, RNA-polymerase activity generates torsional stress in DNA, having a negative impact on the elongation process. Using our previous studies of chromatin fiber structure and conformational transitions, we suggest that this torsional stress can be alleviated, thanks to a tradeoff between the fiber twist and nucleosome conformational transitions into an activated state named "reversome". Our model enlightens the origin of polymerase pauses, and leads to the counterintuitive conclusion that chromatin-organized compaction might facilitate polymerase progression. Indeed, in a compact and well-structured chromatin loop, steric hindrance between nucleosomes enforces sequential transitions, thus ensuring that the polymerase always meets a permissive nucleosomal state.
| S-EPMC2830436 | biostudies-literature
Project description:Summary This protocol provides instructions to track the global dynamics of single epigenetic regulatory factors in live cells. We describe an approach to generate cell lines that stably express HaloTag-fused proteins. We then use live-cell single-molecule tracking to obtain kinetic populations and residence times. The kinetic parameters obtained can be used to determine important aspects of transcriptional regulation such as target-search time, 3D free diffusion time, and number of non-specific sites sampled before reaching a specific site and compare behaviors across different nuclear environments. For complete details on the use and execution of this protocol, please refer to Kent et al. (2020). Graphical abstract Highlights • Generate cell lines stably expressing HaloTag fusion genes• Quantify global binding and target-search kinetics of epigenetic factors• Map binding dynamics of epigenetic factors within transcriptional condensates This protocol provides instructions to track the global dynamics of single epigenetic regulatory factors in live cells. We describe an approach to generate cell lines that stably express HaloTag-fused proteins. We then use live-cell single-molecule tracking to obtain kinetic populations and residence times. The kinetic parameters obtained can be used to determine important aspects of transcriptional regulation such as target-search time, 3D free diffusion time, and number of non-specific sites sampled before reaching a specific site and compare behaviors across different nuclear environments.
| S-EPMC8605088 | biostudies-literature