Nuclear lamin B1 constitutes one of the major structural proteins in the lamina mesh. We silenced the expression of lamin B1 by RNA interference in the colon cancer cell line DLD-1 and showed a dramatic redistribution of H3K27me3 from the periphery to a more homogeneous nuclear dispersion; in addition we observed an increased frequency of micronuclei and nuclear blebs. By 3D-FISH analyses, we demonstrate that the volume and surface of chromosome territories were significantly larger in LMNB1-depleted cells, suggesting that lamin B1 is required to maintain chromatin condensation in interphase nuclei. These changes led to a prolonged S-phase due to activation of Chk1 and telomere attrition. Finally, silencing of LMNB1 resulted in extensive changes in alternative splicing of multiple genes and in a higher number of enlarged nuclear speckles. Taken together, our results suggest a mechanistic role of the nuclear lamina in the organization of chromosome territories, maintenance of genome integrity and proper gene splicing.
Loss of lamin B1 results in prolongation of S phase and decondensation of chromosome territories.
Cell line
View SamplesExon usage analysis in in vitro cultured fibroblast cells. To assay the genome-wide splicing changes during cellular senescence, we performed splicing analysis on young and old normal fibroblasts, and in fibroblasts +/- tert (telomerase protein subunit Tert immortalized).
Progerin and telomere dysfunction collaborate to trigger cellular senescence in normal human fibroblasts.
Specimen part, Disease, Disease stage, Subject
View SamplesThis SuperSeries is composed of the SubSeries listed below.
Correlated alterations in genome organization, histone methylation, and DNA-lamin A/C interactions in Hutchinson-Gilford progeria syndrome.
Sex, Specimen part, Disease, Cell line
View SamplesHutchinson-Gilford progeria syndrome (HGPS) is a premature aging disease that is frequently caused by a de novo point mutation at position 1824 in LMNA. This mutation activates a cryptic splice donor site in exon 11, and leads to an in-frame deletion within the prelamin A mRNA and the production of a dominant negative lamin A protein, known as progerin. Here we show that HGPS cells experience genome-wide alterations in patterns of H3K27me3 deposition, changes in the associations of genomic loci with nuclear lamin A/C, and, at late passages, genome-wide loss of spatial compartmentalization of active and inactive chromatin domains that characterizes chromosome folding in normal cells. We further demonstrate that the H3K27me3 changes associate with gene expression alterations in HGPS cells. Our results support a model that the accumulation of progerin in the nuclear lamina leads to altered H3K27me3 marks in heterochromatin, possibly through the down-regulation of EZH2, and disrupts heterochromatin-lamina interactions. These changes may then lead to the genomic disorganization and changes in transcriptional regulation we observe in HGPS fibroblasts.
Correlated alterations in genome organization, histone methylation, and DNA-lamin A/C interactions in Hutchinson-Gilford progeria syndrome.
Sex, Specimen part, Disease, Cell line
View SamplesCD4+ T-cells isolated from three normal individuals and GM6990 cell lines (three biological replicates) are compared
DNase-chip: a high-resolution method to identify DNase I hypersensitive sites using tiled microarrays.
No sample metadata fields
View SamplesThese samples are being analyzed by the Duke-UNC-Texas-EBI ENCODE consortium. Expression from these cell types will compared to three whole genome open chromatin methodologies: DNaseI hypersensitivity (DNase-seq), Formaldehyde-Assisted Isolation of Regulatory elements (FAIRE-seq), and Chromatin Immunoprecipitation (ChIP-seq) .
Heritable individual-specific and allele-specific chromatin signatures in humans.
Specimen part
View SamplesThe use of nucleic acids from formalin-fixed paraffin-embedded (FFPE) tissues for high-throughput molecular techniques, such as microarray gene expression profiling has become widespread in molecular research area. However, working with FFPE tissues is challenging because of degradation, cross-linking with proteins, and RNA chemical modifications. Also, there is no generally accepted procedure for RNA extraction to microarray analysis. Thus, there is a need for a standardized workflow for FFPE samples to study microarray transcriptome profiling. Therefore, the main purpose of this study was to conduct a standardized process from deparaffinization to RNA extraction and microarray gene expression analysis. Firstly, deparaffinization procedure was optimized for FFPE samples and then Trizol, PicoPure RNA isolation kit, and Qiagen RNeasy FFPE kit performances were compared in terms of yield and purity. Finally, two different cRNA/cDNA preparation and labeling protocols with two different array platforms (Affymetrix Human Genome U133 Plus 2.0 and U133_X3P) were also evaluated to determine which combination gives the best percentage of present call. Our optimization study shows that the Qiagen RNeasy FFPE kit with modified deparaffinization step gives better results (RNA quantity and quality) than the other two isolation kits. The Ribo-SPIA protocol and U133_X3P array combination gave a significantly higher percentage of present calls than the 3 IVT cDNA amplification and labeling system. However, no significant differences were found between the two array platforms. These results present a workflow for microarray gene expression profiling of FFPE tissues. The findings also indicate that sufficient quality gene expression data can be obtained from FFPE-derived RNA.
Optimization of gene expression microarray protocol for formalin-fixed paraffin-embedded tissues.
Specimen part
View SamplesChromatin-based functional genomic analyses and genomewide association studies (GWASs) together implicate enhancers as critical elements influencing gene expression and risk for common diseases. Here, we performed systematic chromatin and transcriptome profiling in human pancreatic islets. Integrated analysis of islet data with those generated by the ENCODE project in nine cell types identified specific and significant enrichment of type 2 diabetes and related quantitative trait GWAS variants in islet enhancers. Our integrated chromatin maps reveal that most enhancers are short (median = 0.8 kb). Each cell type also contains a substantial number of more extended (=3 kb) enhancers. Interestingly, these stretch enhancers are often tissue-specific and overlap locus control regions, suggesting that they are important chromatin regulatory beacons. Indeed, we show that (i) tissue specificity of enhancers and nearby gene expression increase with enhancer length; (ii) neighborhoods containing stretch enhancers are enriched for important cell type-specific genes; and (iii) GWAS variants associated with traits relevant to a particular cell type are more enriched in stretch enhancers compared with short enhancers. Reporter constructs containing stretch enhancer sequences exhibited tissue-specific activity in cell culture experiments and in transgenic mice. These results suggest that stretch enhancers are critical chromatin elements for coordinating cell type-specific regulatory programs and that sequence variation in stretch enhancers affects risk of major common human diseases. Overall design: Integrated analysis of islet chromatin modification and transcriptome data with those generated by the ENCODE project. NISC Comparative Sequencing Program
Chromatin stretch enhancer states drive cell-specific gene regulation and harbor human disease risk variants.
No sample metadata fields
View SamplesExpression profiling was performed using uncultured melanocytes and melanoma cell from various mouse models of BrafV600E induced melanocytic proliferation
mTORC1 activation blocks BrafV600E-induced growth arrest but is insufficient for melanoma formation.
Specimen part
View SamplesPurpose: Identifying target genes of the two human chromatin remodeling enzymes CHD3 and CHD4 Methods: see below in protocols Results: Libraries were sequenced on Illumina HiSeq2000 platform resulting in 37-71 Mio 50 bp paired-end reads per sample. We identified 16 (i) and 115 (ii) distinctly regulated genes when CHD3-GFP (i) or CHD4-GFP (ii) were overexpressed. Nine genes seem to be commonly regulated by CHD3 and CHD4. We successfully validated four genes from our RNA-seq via qPCR with two new (independent from those, used for RNA-seq) biological replicates. Conclusion: CHD3 and CHD4 regulate distinct genes. Overall design: Total RNA was prepared from 24 hours induced (1 ng/µl Dox) and non-induced Flp-In™ T-REx™ 293 cells, expressing GFP, hCHD3-GFP (UniProt: Q12873) or hCHD4-GFP(UniProt Q14839). Library preparation and Illumina Sequencing was perfprmed by EMBL GeneCore facility in Heidelberg (Germany: Dr. Vladimir Benes)
CHD3 and CHD4 form distinct NuRD complexes with different yet overlapping functionality.
Cell line, Subject
View Samples