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  • 1
    Publication Date: 2013-08-09
    Description: In developing B cells, the immunoglobulin heavy chain ( IgH ) locus is thought to move from repressive to permissive chromatin compartments to facilitate its scheduled rearrangement. In mature B cells, maintenance of allelic exclusion has been proposed to involve recruitment of the non-productive IgH allele to pericentromeric heterochromatin. Here, we used an allele-specific chromosome conformation capture combined with sequencing (4C-seq) approach to unambigously follow the individual IgH alleles in mature B lymphocytes. Despite their physical and functional difference, productive and non-productive IgH alleles in B cells and unrearranged IgH alleles in T cells share many chromosomal contacts and largely reside in active chromatin. In brain, however, the locus resides in a different repressive environment. We conclude that IgH adopts a lymphoid-specific nuclear location that is, however, unrelated to maintenance of allelic exclusion. We additionally find that in mature B cells—but not in T cells—the distal V H regions of both IgH alleles position themselves away from active chromatin. This, we speculate, may help to restrict enhancer activity to the productively rearranged V H promoter element.
    Keywords: Massively Parallel (Deep) Sequencing
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 142 (1990), S. 441-448 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Swiss 3T3 cells express receptors for both the polypeptide epidermal growth factor (EGF) and the tetradecapeptide bombesin and respond mitogenically to these substances. These cells thus provide a system to analyze potential signal transduction pathways involved in mitogenic stimulation. Here we have determined and compared the early ionic responses elicited by EGF and bombesin and their relation to diacylglycerol (DG) and inositolphosphate (InsPn) production. Whereas EGF fails to cause any significant change in intracellular Ca2+ bombesin effectively induces prompt and transient Ca2+ mobilization from intracellular stores. Further support of the idea that these receptors utilize distinct signalling pathways comes from the measurements of cytoplasmic pH (pHi). As in most target cells, EGF induces a delayed (1 min) but sustained intracellular alkalinization that reaches a new steady state after ∼10 min. Bombesin, in contrast, elicits a biphasic response; within seconds, a rapid but transient rise in pHi is observed, followed by a further slower sustained alkalinization. Inhibition of the Na+/H+ exchanger prevents both EGF as well as bombesin-induced alkalinization. However, under these conditions, bombesin evokes a rapid and sustained acidification related to the Ca2+ response. Apparently, bombesin initiates a Ca2+ -dependent acidifying process immediately after binding of the hormone to its receptor. Furthermore, we could demonstrate that the bombesin-induced alkalinization depends on protein kinase C activation whereas the EGF response does not. Determination of the total DG and InsPn accumulation revealed that EGF is ineffective in stimulating phospholipase C-mediated production of these second messengers. In contrast, bombesin causes a rapid DG and InsPn production coinciding with the Ca2+ response and the first phase of the rise in pHi followed by a slower DG accumulation coinciding with the second alkalinization phase. Our results show that in Swiss 3T3 cells the bombesin receptor activates the hydrolysis of inositol lipids as a mechanism of signal transduction, which consequently causes changes in Ca2+i and pHi. Clearly, the EGF receptor utilizes different pathways to evoke mitogenisis and stimulates Na+/H+ exchange independently of DG production and protein kinase C activation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Publication Date: 2008-05-09
    Description: The architecture of human chromosomes in interphase nuclei is still largely unknown. Microscopy studies have indicated that specific regions of chromosomes are located in close proximity to the nuclear lamina (NL). This has led to the idea that certain genomic elements may be attached to the NL, which may contribute to the spatial organization of chromosomes inside the nucleus. However, sequences in the human genome that interact with the NL in vivo have not been identified. Here we construct a high-resolution map of the interaction sites of the entire genome with NL components in human fibroblasts. This map shows that genome-lamina interactions occur through more than 1,300 sharply defined large domains 0.1-10 megabases in size. These lamina-associated domains (LADs) are typified by low gene-expression levels, indicating that LADs represent a repressive chromatin environment. The borders of LADs are demarcated by the insulator protein CTCF, by promoters that are oriented away from LADs, or by CpG islands, suggesting possible mechanisms of LAD confinement. Taken together, these results demonstrate that the human genome is divided into large, discrete domains that are units of chromosome organization within the nucleus.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Guelen, Lars -- Pagie, Ludo -- Brasset, Emilie -- Meuleman, Wouter -- Faza, Marius B -- Talhout, Wendy -- Eussen, Bert H -- de Klein, Annelies -- Wessels, Lodewyk -- de Laat, Wouter -- van Steensel, Bas -- England -- Nature. 2008 Jun 12;453(7197):948-51. doi: 10.1038/nature06947. Epub 2008 May 7.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Division of Molecular Biology, Netherlands Cancer Institute, Plesmanlaan 121, Amsterdam, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18463634" target="_blank"〉PubMed〈/a〉
    Keywords: Cell Line ; Chromatin/genetics/metabolism ; *Chromosome Positioning ; Chromosomes, Human/genetics/*metabolism ; CpG Islands/genetics ; DNA-Binding Proteins/metabolism ; Fibroblasts ; Genome, Human ; Humans ; Lamin Type B/metabolism ; Nuclear Lamina/chemistry/*metabolism ; Promoter Regions, Genetic/genetics ; Protein Binding ; Repressor Proteins/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2011-10-15
    Description: The spatial and temporal control of Hox gene transcription is essential for patterning the vertebrate body axis. Although this process involves changes in histone posttranslational modifications, the existence of particular three-dimensional (3D) architectures remained to be assessed in vivo. Using high-resolution chromatin conformation capture methodology, we examined the spatial configuration of Hox clusters in embryonic mouse tissues where different Hox genes are active. When the cluster is transcriptionally inactive, Hox genes associate into a single 3D structure delimited from flanking regions. Once transcription starts, Hox clusters switch to a bimodal 3D organization where newly activated genes progressively cluster into a transcriptionally active compartment. This transition in spatial configurations coincides with the dynamics of chromatin marks, which label the progression of the gene clusters from a negative to a positive transcription status. This spatial compartmentalization may be key to process the colinear activation of these compact gene clusters.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Noordermeer, Daan -- Leleu, Marion -- Splinter, Erik -- Rougemont, Jacques -- De Laat, Wouter -- Duboule, Denis -- New York, N.Y. -- Science. 2011 Oct 14;334(6053):222-5. doi: 10.1126/science.1207194.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉National Research Centre Frontiers in Genetics, School of Life Sciences, Ecole Polytechnique Federale (EPFL), Lausanne, Switzerland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21998387" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Chromatin/metabolism/ultrastructure ; Embryo, Mammalian/cytology/*metabolism ; Gene Expression Regulation, Developmental ; *Genes, Homeobox ; Histones/metabolism ; Mice ; Models, Genetic ; *Multigene Family ; Transcription, Genetic ; *Transcriptional Activation
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2013-07-26
    Description: It is becoming increasingly clear that the shape of the genome importantly influences transcription regulation. Pluripotent stem cells such as embryonic stem cells were recently shown to organize their chromosomes into topological domains that are largely invariant between cell types. Here we combine chromatin conformation capture technologies with chromatin factor binding data to demonstrate that inactive chromatin is unusually disorganized in pluripotent stem-cell nuclei. We show that gene promoters engage in contacts between topological domains in a largely tissue-independent manner, whereas enhancers have a more tissue-restricted interaction profile. Notably, genomic clusters of pluripotency factor binding sites find each other very efficiently, in a manner that is strictly pluripotent-stem-cell-specific, dependent on the presence of Oct4 and Nanog protein and inducible after artificial recruitment of Nanog to a selected chromosomal site. We conclude that pluripotent stem cells have a unique higher-order genome structure shaped by pluripotency factors. We speculate that this interactome enhances the robustness of the pluripotent state.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Wit, Elzo -- Bouwman, Britta A M -- Zhu, Yun -- Klous, Petra -- Splinter, Erik -- Verstegen, Marjon J A M -- Krijger, Peter H L -- Festuccia, Nicola -- Nora, Elphege P -- Welling, Maaike -- Heard, Edith -- Geijsen, Niels -- Poot, Raymond A -- Chambers, Ian -- de Laat, Wouter -- G0901533/Medical Research Council/United Kingdom -- England -- Nature. 2013 Sep 12;501(7466):227-31. doi: 10.1038/nature12420. Epub 2013 Jul 24.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Hubrecht Institute-KNAW & University Medical Center Utrecht, Uppsalalaan 8, 3584 CT Utrecht, The Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23883933" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Binding Sites ; Cell Line ; Chromatin/*chemistry/genetics/*metabolism ; Chromatin Immunoprecipitation ; *Chromosome Positioning ; Embryonic Stem Cells/cytology/metabolism ; Enhancer Elements, Genetic ; Genome/*genetics ; Homeodomain Proteins/metabolism ; *Imaging, Three-Dimensional ; Induced Pluripotent Stem Cells/cytology/metabolism ; Mice ; Molecular Imaging ; Octamer Transcription Factor-3/metabolism ; Organ Specificity ; Pluripotent Stem Cells/*cytology/*metabolism ; Promoter Regions, Genetic ; SOXB1 Transcription Factors/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2013-10-25
    Description: How a complex animal can arise from a fertilized egg is one of the oldest and most fascinating questions of biology, the answer to which is encoded in the genome. Body shape and organ development, and their integration into a functional organism all depend on the precise expression of genes in space and time. The orchestration of transcription relies mostly on surrounding control sequences such as enhancers, millions of which form complex regulatory landscapes in the non-coding genome. Recent research shows that high-order chromosome structures make an important contribution to enhancer functionality by triggering their physical interactions with target genes.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉de Laat, Wouter -- Duboule, Denis -- England -- Nature. 2013 Oct 24;502(7472):499-506. doi: 10.1038/nature12753.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Hubrecht Institute-KNAW and University Medical Center Utrecht, Uppsalalaan 8, 3584 CT, Utrecht, the Netherlands.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/24153303" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; DNA/chemistry/genetics/metabolism ; Enhancer Elements, Genetic/*genetics ; Evolution, Molecular ; Gene Expression Regulation, Developmental/*genetics ; Genome/genetics ; Humans ; Mammals/*genetics ; Nucleic Acid Conformation ; Promoter Regions, Genetic/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 1990-03-01
    Print ISSN: 0021-9541
    Electronic ISSN: 1097-4652
    Topics: Biology , Medicine
    Published by Wiley
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  • 8
    Publication Date: 2012-10-24
    Description: Although chromatin folding is known to be of functional importance to control the gene expression program, less is known regarding its interplay with DNA replication. Here, using Circular Chromatin Conformation Capture combined with high-throughput sequencing, we identified megabase-sized self-interacting domains in the nucleus of a human lymphoblastoid cell line, as well as in cycling and resting peripheral blood mononuclear cells (PBMC). Strikingly, the boundaries of those domains coincide with early-initiation zones in every cell types. Preferential interactions have been observed between the consecutive early-initiation zones, but also between those separated by several tens of megabases. Thus, the 3D conformation of chromatin is strongly correlated with the replication timing along the whole chromosome. We furthermore provide direct clues that, in addition to the timing value per se , the shape of the timing profile at a given locus defines its set of genomic contacts. As this timing-related scheme of chromatin organization exists in lymphoblastoid cells, resting and cycling PBMC, this indicates that it is maintained several weeks or months after the previous S-phase. Lastly, our work highlights that the major chromatin changes accompanying PBMC entry into cell cycle occur while keeping largely unchanged the long-range chromatin contacts.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 9
    Publication Date: 1998-09-15
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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