Project description:The mechanisms underlying nuclear body (NB) formation and their contribution to genome function are unknown. We examined the non-random positioning of Cajal bodies (CBs), major NBs involved in spliceosomal snRNP assembly, and their role in genome organization. CBs are predominantly located at the periphery of chromosome territories at a multi-chromosome interface. Genome-wide chromatin conformation capture analysis (4C-seq) using CB-interacting loci revealed that CB-associated regions are enriched with highly expressed histone genes and U small nuclear and nucleoar RNA (sn/snoRNA) loci that form intra- and inter-chromosomal clusters. We observed a number of CB-dependent gene positioning events on chromosome 1. RNAi-mediated disassembly of CBs disrupts the CB-targeting gene clusters and suppresses the expression of U sn/snoRNA and histone genes. This loss of spliceosomal snRNP production resulted in increased splicing noise, even in CB-distal regions. We conclude that CBs contribute to genome organization with global effects on gene expression and RNA splicing fidelity.
Project description:By CRISPR DNA-fragment editing, in conjunction with chromosome conformation capture, we find that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation in silico and genetic deletions in vivo revealed balanced promoter usage in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
Project description:CTCF is a key insulator-binding protein and mammalian genomes contain numerous CTCF-binding sites (CBSs), many of which are organized in tandem arrays. Here we provide direct evidence that CBSs, if located between enhancers and promoters in the clustered Pcdh and b-globin clusters, function as an enhancer-blocking insulator by forming distinct directional chromatin loops, regardless whether enhancers contain CBS or not. Moreover, computational simulation and experimental capture revealed balanced promoter usage in vivo in cell populations and stochastic monoallelic expression in single cells by large arrays of tandem variable CBSs. Finally, gene expression levels are negatively correlated with CBS insulators located between enhancers and promoters on a genome-wide scale. Thus, single CBS insulators ensure proper enhancer insulation and promoter activation while tandem-arrayed CBS insulators determine balanced promoter choice. This finding has interesting implications on the role of topological insulators in 3D genome folding and developmental gene regulation.
Project description:CTCF plays an important role in 3D genome organization by adjusting insulation at TAD boundaries, where clustered CBS (CTCF-binding site) elements are often arranged in tandem array with a complex divergent or convergent orientation. Here using cPcdh and HOXD loci as a paradigm, we look into the clustered CTCF TAD boundaries and find that, counterintuitively, outward-oriented CBS elements are crucial for inward enhancer-promoter interactions as well as for gene regulation. Specifically, by combinatorial deletions of a series of putative enhancer elements in vivo or CBS elements in vitro, in conjunction with chromosome conformation capture and RNA-seq analyses, we show that deletions of outward-oriented CBS elements weaken the strength of long-distance intraTAD promoter-enhancer interactions and enhancer activation of target genes. Our data highlight the crucial role of outward-oriented CBS elements within the clustered CTCF TAD boundaries and have interesting implications on the organization principles of clustered CTCF sites within TAD boundaries.
Project description:CTCF plays an important role in 3D genome organization by adjusting insulation at TAD boundaries, where clustered CBS (CTCF-binding site) elements are often arranged in tandem array with a complex divergent or convergent orientation. Here using cPcdh and HOXD loci as a paradigm, we look into the clustered CTCF TAD boundaries and find that, counterintuitively, outward-oriented CBS elements are crucial for inward enhancer-promoter interactions as well as for gene regulation. Specifically, by combinatorial deletions of a series of putative enhancer elements in vivo or CBS elements in vitro, in conjunction with chromosome conformation capture and RNA-seq analyses, we show that deletions of outward-oriented CBS elements weaken the strength of long-distance intraTAD promoter-enhancer interactions and enhancer activation of target genes. Our data highlight the crucial role of outward-oriented CBS elements within the clustered CTCF TAD boundaries and have interesting implications on the organization principles of clustered CTCF sites within TAD boundaries.
Project description:Primary objectives: The primary objective is to investigate circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Primary endpoints: circulating tumor DNA (ctDNA) via deep sequencing for mutation detection and by whole genome sequencing for copy number analyses before start (baseline) with regorafenib and at defined time points during administration of regorafenib for treatment efficacy in colorectal cancer patients in terms of overall survival (OS).
Project description:RNA sequencing of heterozygote or Tudor domain contian protein 6 (TDRD6) knockout round spermatid cells. Chromatoid bodies (CBs) are germ cell-specific organelles of largely unknown function. CBs harbor various RNA species, RNA-associated proteins and proteins of the tudor domain family such as TDRD6. Proteome analysis of purified CBs revealed components of the nonsense-mediated mRNA decay machinery such as UPF1. TDRD6 is essential for UPF1 localization to CBs, for UPF1-UPF2 interaction, and for assembly of UPFs and other RNA binding proteins into super-complexes. In absence of TDRD6, the association of some mRNAs with UPF1 is impaired, and the long 3â UTR-stimulated but not the exon junction complex-stimulated pathway of NMD is distorted. Reduced association of mRNAs with UPF1 correlated with increased stability and presence in polysome fractions, i.e. enhanced translational activity. Thus, we define CBs as sites of UPF1-dependent mRNA degradation and provide evidence for the requirement for NMD in spermiogenesis. This function of CBs depends on TDRD6-promoted assembly of mRNA decay enzymes within mRNPs. RNA was extracted from quadruplicate samples and libraries generated for sequencing using the NEBNext Ultra Directional RNA Library Prep Kit (New England Biolabs) at the Deep Sequencing Group SFB 655, Biotechnology Center of Technische Universität Dresden. After enrichment and XP bead (Agencourt AMPure Kit; Beckman Coulter, Inc.) purification, quality control was done using Fragment AnalyzerTM (Advanced Analytical). The bar-coded libraries were equimolarly pooled and subjected to 76 bp single-end sequencing on Illumina HiSeq 2000, resulting in an average of 33 million reads per sample.