Epigenetics of Cellular Memory: Insights from the Chromatin Accessibility Landscape of the Mitotic Genome

Blood ◽  
2014 ◽  
Vol 124 (21) ◽  
pp. 4342-4342
Author(s):  
Chris C.S. Hsiung ◽  
Christapher Morrissey ◽  
Maheshi Udugama ◽  
Christopher Frank ◽  
Cheryl A. Keller ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Transcription Factors ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Dnase I ◽  
Specific Gene ◽  
Tissue Specific ◽  
Dnase I Sensitivity ◽  
Mitotic Chromatin

Abstract Normal development requires the coordination of cell cycle progression and gene expression to produce physiologically appropriate cell numbers of various lineages. The concomitant dysregulation of these two cellular programs is central to many malignant and non-malignant hematologic diseases, yet researchers still lack clear, general principles of how intrinsic properties of cell division could influence transcriptional regulation. Mitosis is a unique phase of the cell cycle that dramatically disrupts transcription: chromosomes condense to form microscopically recognizable structures, the nucleus is disassembled, RNA synthesis ceases, and the transcription machinery and many transcription factors are evicted from mitotic chromatin. How cells “remember” tissue-specific transcriptional programs through mitotic divisions remains largely unknown. Some transcription factors, including the erythroid master regulator, GATA1, and certain chromatin features are known to remain associated with DNA during mitosis. These molecular entities have been proposed to serve as mitotic “bookmarks” -- molecules that store gene regulatory information at individual loci through mitosis. However, we have limited knowledge of the composition, mechanism and function of mitotic bookmarks. In this context, chromatin structure deserves special consideration, as chromosome condensation during mitosis could potentially hinder transcription factor binding. To obtain the first genome-wide view of chromatin accessibility during mitosis, we mapped the DNase I sensitivity of the interphase versus mitotic genome in two maturation stages in a murine erythroblast cell line, G1E. Despite microscopic condensation of chromosomes during mitosis, we found that DNase I sensitivity is extensively preserved throughout the mappable genome, indicating that mitotic chromatin is not as condensed as commonly presumed. Individual genes and cis-regulatory elements can maintain all, part of, or none of its interphase accessibility during mitosis, demonstrating that accessibility of mitotic chromatin is locally specified. Promoters generally maintain accessibility during mitosis; moreover, promoters with the highest degree of accessibility preservation in mitosis in G1E cells tend to also be accessible across many murine tissues in interphase. In contrast to promoters, we found that enhancer accessibility is preferentially lost during mitosis, raising the possibility that memory of enhancer regulation may be altered during mitosis. Since enhancers play crucial roles in specifying tissue-specific gene expression patterns, we propose that this phase of the cell cycle may be especially susceptible to resetting of transcriptional programs. This hypothesis is supported by our preliminary results that revealed aberrant RNA polymerase II re-engagement with the genome and transcript production in early G1. Thus, mitosis could be a source of gene expression heterogeneity, with potential implications for cell fate transitions in proliferative cells, such as during stem cell lineage commitment, experimental reprogramming, and tumorigenesis. Disclosures No relevant conflicts of interest to declare.

scholarly journals T cell receptor beta gene has two downstream DNase I hypersensitive regions. Possible mechanisms of tissue- and stage-specific gene regulation.

1989 ◽  
Vol 169 (6) ◽  
pp. 2097-2107 ◽  
Author(s):  
Y Hashimoto
Keyword(s):  
Gene Expression ◽  
T Cell ◽  
Cell Lines ◽  
Regulatory Elements ◽  
Dnase I ◽  
The Other ◽  
Specific Gene ◽  
Enhancer Element ◽  
Tissue Specific ◽  
T Cell Lines

Two DNase I-hypersensitive regions were identified downstream of the TCR gene constant region. One of these regions is located at the site of a putative enhancer element and was observed only in T cell lines and not in cell lines derived from other tissues. The other DNase-hypersensitive region was also detected only in T cell lines but only in those expressing TCR-beta RNA. Thus, the first region is probably tissue specific, while the second region is probably tissue and stage specific. The DNA sequence of the second DNase I-hypersensitive region revealed several stretches of nucleotides that are characteristic of consensus sequences for regulatory elements. These results, together with the observations in transgenic mice that indicate a requirement for two distinct regions for optimal TCR gene expression, suggest the presence of at least two regulatory regions downstream of the C-beta-2 region; one is an enhancer region and the other is a transcriptionally related regulatory region. The tissue/stage specificity of these DNase I-hypersensitive regions supports the notion that changes in chromatin structure control tissue-specific gene expression.

scholarly journals The regulatory genome of the malaria vector Anopheles gambiae: integrating chromatin accessibility and gene expression

2021 ◽  
Vol 3 (1) ◽  
Author(s):  
José L Ruiz ◽  
Lisa C Ranford-Cartwright ◽  
Elena Gómez-Díaz
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Anopheles Gambiae ◽  
Mosquito Control ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Malaria Vectors ◽  
Specific Gene ◽  
Mosquito Vector ◽  
Human Malaria

Abstract Anopheles gambiae mosquitoes are primary human malaria vectors, but we know very little about their mechanisms of transcriptional regulation. We profiled chromatin accessibility by the assay for transposase-accessible chromatin by sequencing (ATAC-seq) in laboratory-reared A. gambiae mosquitoes experimentally infected with the human malaria parasite Plasmodium falciparum. By integrating ATAC-seq, RNA-seq and ChIP-seq data, we showed a positive correlation between accessibility at promoters and introns, gene expression and active histone marks. By comparing expression and chromatin structure patterns in different tissues, we were able to infer cis-regulatory elements controlling tissue-specific gene expression and to predict the in vivo binding sites of relevant transcription factors. The ATAC-seq assay also allowed the precise mapping of active regulatory regions, including novel transcription start sites and enhancers that were annotated to mosquito immune-related genes. Not only is this study important for advancing our understanding of mechanisms of transcriptional regulation in the mosquito vector of human malaria, but the information we produced also has great potential for developing new mosquito-control and anti-malaria strategies.

scholarly journals Gastrointestinal transcription factors drive lineage-specific developmental programs in organ specification and cancer

2019 ◽  
Vol 5 (12) ◽  
pp. eaax8898 ◽  
Author(s):  
Roshane Francis ◽  
Haiyang Guo ◽  
Catherine Streutker ◽  
Musaddeque Ahmed ◽  
Theodora Yung ◽  
...  
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Epigenetic Regulation ◽  
Gastrointestinal Cancer ◽  
Chromatin Accessibility ◽  
Lineage Specification ◽  
Developmental Programs ◽  
Tissue Specific ◽  
Cancer Data ◽  
Gastrointestinal Tissue

Transcription factors (TFs) are spatially and temporally regulated during gut organ specification. Although accumulating evidence shows aberrant reactivation of developmental programs in cancer, little is known about how TFs drive lineage specification in development and cancer. We first defined gastrointestinal tissue–specific chromatin accessibility and gene expression during development, identifying the dynamic epigenetic regulation of SOX family of TFs. We revealed that Sox2 is not only essential for gastric specification, by maintaining chromatin accessibility at forestomach lineage loci, but also sufficient to promote forestomach/esophageal transformation upon Cdx2 deletion. By comparing our gastrointestinal lineage-specific transcriptome to human gastrointestinal cancer data, we found that stomach and intestinal lineage-specific programs are reactivated in Sox2high/Sox9high and Cdx2high cancers, respectively. By analyzing mice deleted for both Sox2 and Sox9, we revealed their potentially redundant roles in both gastric development and cancer, highlighting the importance of developmental lineage programs reactivated by gastrointestinal TFs in cancer.

scholarly journals Identifying Transcription Regulatory Elements in the Human and Mouse Genomes Using Tissue-specific Gene Expression Profiles

2007 ◽  
Vol 4 (2) ◽  
pp. 1-23
Author(s):  
Amitava Karmaker ◽  
Kihoon Yoon ◽  
Mark Doderer ◽  
Russell Kruzelock ◽  
Stephen Kwek
Keyword(s):  
Gene Expression ◽  
Transcription Factor ◽  
Transcription Factors ◽  
Binding Sites ◽  
Expression Profiles ◽  
Gene Expression Profiles ◽  
Regulatory Elements ◽  
Specific Gene ◽  
Tissue Specific Gene ◽  
Human And Mouse

Summary Revealing the complex interaction between trans- and cis-regulatory elements and identifying these potential binding sites are fundamental problems in understanding gene expression. The progresses in ChIP-chip technology facilitate identifying DNA sequences that are recognized by a specific transcription factor. However, protein-DNA binding is a necessary, but not sufficient, condition for transcription regulation. We need to demonstrate that their gene expression levels are correlated to further confirm regulatory relationship. Here, instead of using a linear correlation coefficient, we used a non-linear function that seems to better capture possible regulatory relationships. By analyzing tissue-specific gene expression profiles of human and mouse, we delineate a list of pairs of transcription factor and gene with highly correlated expression levels, which may have regulatory relationships. Using two closely-related species (human and mouse), we perform comparative genome analysis to cross-validate the quality of our prediction. Our findings are confirmed by matching publicly available TFBS databases (like TRANFAC and ConSite) and by reviewing biological literature. For example, according to our analysis, 80% and 85.71% of the targets genes associated with E2F5 and RELB transcription factors have the corresponding known binding sites. We also substantiated our results on some oncogenes with the biomedical literature. Moreover, we performed further analysis on them and found that BCR and DEK may be regulated by some common transcription factors. Similar results for BTG1, FCGR2B and LCK genes were also reported.

scholarly journals The regulatory genome of the malaria vector Anopheles gambiae: integrating chromatin accessibility and gene expression

2020 ◽  
Author(s):  
José L. Ruiz ◽  
Lisa C. Ranford-Cartwright ◽  
Elena Gómez-Díaz
Keyword(s):  
Gene Expression ◽  
Transcriptional Regulation ◽  
Anopheles Gambiae ◽  
Mosquito Control ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Malaria Vectors ◽  
Specific Gene ◽  
Mosquito Vector ◽  
Human Malaria

ABSTRACTAnopheles gambiae mosquitoes are primary human malaria vectors, but we know very little about mechanisms of transcriptional regulation. We profiled chromatin accessibility by ATAC-seq in laboratory-reared An. gambiae mosquitoes experimentally infected with the human malaria parasite Plasmodium falciparum. By integrating ATAC-seq, RNA-seq and ChIP-seq data we showed a positive correlation between accessibility at promoters and introns, gene expression and active histone marks. By comparing expression and chromatin structure patterns in different tissues, we were able to infer cis-regulatory elements controlling tissue specific gene expression and to predict the in vivo binding sites of relevant transcription factors. The ATAC-seq assay also allowed the precise mapping of active regulatory regions, including novel transcription start sites and enhancers that annotate to mosquito immune-response genes. This study is important not only for advancing our understanding of mechanisms of transcriptional regulation in the mosquito vector of human malaria, but the information is of great potential for developing new mosquito-control and anti-malaria strategies.

scholarly journals Regulation of Differentiation by HBP1, a Target of the Retinoblastoma Protein

1998 ◽  
Vol 18 (8) ◽  
pp. 4732-4743 ◽  
Author(s):  
Heather H. Shih ◽  
Sergei G. Tevosian ◽  
Amy S. Yee
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Cell Differentiation ◽  
Retinoblastoma Protein ◽  
Specific Gene ◽  
Cell Cycle Exit ◽  
Tissue Specific ◽  
Tissue Specific Gene ◽  
Specific Gene Expression ◽  
Relative Ratio

ABSTRACT Differentiation is a coordinated process of irreversible cell cycle exit and tissue-specific gene expression. To probe the functions of the retinoblastoma protein (RB) family in cell differentiation, we isolated HBP1 as a specific target of RB and p130. Our previous work showed that HBP1 was a transcriptional repressor and a cell cycle inhibitor. The induction of HBP1, RB, and p130 upon differentiation in the muscle C2C12 cells suggested a coordinated role. Here we report that the expression of HBP1 unexpectedly blocked muscle cell differentiation without interfering with cell cycle exit. Moreover, the expression of MyoD and myogenin, but not Myf5, was inhibited in HBP1-expressing cells. HBP1 inhibited transcriptional activation by the MyoD family members. The inhibition of MyoD family function by HBP1 required binding to RB and/or p130. Since Myf5 might function upstream of MyoD, our data suggested that HBP1 probably blocked differentiation by disrupting Myf5 function, thus preventing expression of MyoD and myogenin. Consistent with this, the expression of each MyoD family member could reverse the inhibition of differentiation by HBP1. Further investigation implicated the relative ratio of RB to HBP1 as a determinant of whether cell cycle exit or full differentiation occurred. At a low RB/HBP1 ratio cell cycle exit occurred but there was no tissue-specific gene expression. At elevated RB/HBP1 ratios full differentiation occurred. Similar changes in the RB/HBP1 ratio have been observed in normal C2 differentiation. Thus, we postulate that the relative ratio of RB to HBP1 may be one signal for activation of the MyoD family. We propose a model in which a checkpoint of positive and negative regulation may coordinate cell cycle exit with MyoD family activation to give fidelity and progression in differentiation.

scholarly journals The Developmental Control of Osteoblast-Specific Gene Expression: Role of Specific Transcription Factors and the Extracellular Matrix Environment

1999 ◽  
Vol 10 (1) ◽  
pp. 40-57 ◽  
Author(s):  
R.T. Franceschi
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Dna Sequences ◽  
Developmental Process ◽  
Positional Information ◽  
Cleidocranial Dysplasia ◽  
Specific Gene ◽  
Tissue Specific ◽  
Specific Gene Expression ◽  
Specific Differentiation

Bone formation is a carefully controlled developmental process involving morphogen-mediated patterning signals that define areas of initial mesenchyme condensation followed by induction of cell-specific differentiation programs to produce chondrocytes and osteoblasts. Positional information is conveyed via gradients of molecules, such as Sonic Hedgehog that are released from cells within a particular morphogenic field together with region-specific patterns of hox gene expression. These, in turn, regulate the localized production of bone morphogenetic proteins and related molecules which initiate chondrocyte- and osteoblast-specific differentiation programs. Differentiation requires the initial commitment of mesenchymal stem cells to a given lineage, followed by induction of tissue-specific patterns of gene expression. Considerable information about the control of osteoblast-specific gene expression has come from analysis of the promoter regions of genes encoding proteins like osteocalcin that are selectively expressed in bone. Both general and tissue-specific transcription factors control this promoter. Osf2/Cbfal, the first osteoblast-specific transcription factor to be identified, is expressed early in the osteoblast lineage and interacts with specific DNA sequences in the osteocalcin promoter essential for its selective expression in osteoblasts. The OSF2/CBFA1 gene is necessary for the development of mineralized tissues, and its mutation causes the human disease, cleidocranial dysplasia. Committed osteoprogenitor cells already expressing Osf2/Cbfa1 must synthesize a collagenous ECM before they will differentiate. A ceII:ECM interaction mediated by integrin-type cell-surface receptors is essential for the induction of osteocalcin and other osteoblast-related proteins. This interaction stimulates the binding of Osf2/Cbfa 1 to the osteocalcin promoter through an as-yet-undefined mechanism.

scholarly journals Cis acting variation is common, can propagates across multiple regulatory layers, but is often buffered in developmental programs

2020 ◽  
Author(s):  
Swann Floc’hlay ◽  
Emily Wong ◽  
Bingqing Zhao ◽  
Rebecca R. Viales ◽  
Morgane Thomas-Chollier ◽  
...  
Keyword(s):  
Gene Expression ◽  
Genetic Variation ◽  
Transcription Factors ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Cis Acting ◽  
Dna Mutations ◽  
Allele Specific ◽  
Regulatory Dna ◽  
The Impact

AbstractPrecise patterns of gene expression are driven by interactions between transcription factors, regulatory DNA sequence, and chromatin. How DNA mutations affecting any one of these regulatory ‘layers’ is buffered or propagated to gene expression remains unclear. To address this, we quantified allele-specific changes in chromatin accessibility, histone modifications, and gene expression in F1 embryos generated from eight Drosophila crosses, at three embryonic stages, yielding a comprehensive dataset of 240 samples spanning multiple regulatory layers. Genetic variation in cis-regulatory elements is common, highly heritable, and surprisingly consistent in its effects across embryonic stages. Much of this variation does not propagate to gene expression. When it does, it acts through H3K4me3 or alternatively through chromatin accessibility and H3K27ac. The magnitude and evolutionary impact of mutations is influenced by a genes’ regulatory complexity (i.e. enhancer number), with transcription factors being most robust to cis-acting, and most influenced by trans-acting, variation. Overall, the impact of genetic variation on regulatory phenotypes appears context-dependent even within the constraints of embryogenesis.

scholarly journals SNPnotes: high-throughput tissue-specific functional annotation of single nucleotide variants

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1784
Author(s):  
Shraddha Pai ◽  
Michael J. Apostolides ◽  
Andrew Jung ◽  
Matthew A. Moss
Keyword(s):  
Gene Expression ◽  
Gene Mapping ◽  
High Throughput ◽  
Regulatory Elements ◽  
Specific Gene ◽  
Tissue Specific ◽  
Functional Variants ◽  
Genome Regulation ◽  
Organ Systems ◽  
Variant Gene

A key challenge in the application of whole-genome sequencing (WGS) for clinical diagnostic and research is the high-throughput prioritization of functional variants in the non-coding genome. This challenge is compounded by context-specific genetic modulation of gene expression, and variant-gene mapping depends on the tissues and organ systems affected in a given disease; for instance, a disease affecting the gastrointestinal system would use maps specific to genome regulation in gut-related tissues. While there are large-scale atlases of genome regulation, such as GTEx and NIH Roadmap Epigenomics, the clinical genetics community lacks publicly-available stand-alone software for high-throughput annotation of custom variant data with user-defined tissue-specific epigenetic maps and clinical genetic databases, to prioritize variants for a specific biomedical application. In this work, we provide a simple software pipeline, called SNPnotes, which takes as input variant calls for a patient and prioritizes those using information on clinical relevance from ClinVar, tissue-specific gene regulation from GTEx and disease associations from the NHGRI-EBI GWAS catalogue. This pipeline was developed as part of SVAI Research's "Undiagnosed-1" event for collaborative patient diagnosis. We applied this pipeline to WGS-based variant calls for an individual with a history of gastrointestinal symptoms, using 12 gut-specific eQTL maps and GWAS associations for metabolic diseases, for variant-gene mapping. Out of 6,248,584 SNPs, the pipeline identified 151 high-priority variants, overlapping 129 genes. These top SNPs all have known clinical pathogenicity, modulate gene expression in gut tissues and have genetic associations with metabolic disorders, and serve as starting points for hypotheses about mechanisms driving clinical symptoms. Simple software changes can be made to customize the pipeline for other tissue-specific applications. Future extensions could integrate maps of tissue-specific regulatory elements, higher-order chromatin loops, and mutations affecting splice variants.

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