scholarly journals A long-range chromatin interaction regulates SATB homeobox 1 gene expression in trophoblast stem cells

2020 ◽  
Author(s):  
Wei Yu ◽  
V. Praveen Chakravarthi ◽  
Shaon Borosha ◽  
Anamika Ratri ◽  
Khyati Dalal ◽  
...  

ABSTRACTSATB homeobox proteins are important regulators of developmental gene expression. Among the stem cell lineages determined during early embryonic development, trophoblast stem (TS) cells exhibit robust SATB expression. Both SATB1 and SATB2 act to maintain trophoblast stem-state. However, the molecular mechanisms that regulate TS-specific Satb expression are not yet known. We identified Satb1 variant 2 as the predominant transcript in trophoblasts. Histone marks, and RNA polymerase II occupancy in TS cells indicated active state of the promoter. A novel cis-regulatory region with active histone marks was identified ∼21kbp upstream of variant 2 promoter. CRISPR/Cas9 mediated disruption of this sequence decreased Satb1 expression in TS cells and chromatin conformation capture confirmed looping of this regulatory region into the promoter. Scanning position weight matrices across the enhancer predicted two ELF5 binding sites in close vicinity of SATB1 sites, which were confirmed by chromatin immunoprecipitation. Knockdown of ELF5 downregulated Satb1 expression in TS cells and overexpression of ELF5 increased the enhancer-reporter activity. Interestingly, ELF5 interacts with SATB1 in TS cells, and the enhancer activity was upregulated following SATB overexpression. Our findings indicate that trophoblast-specific Satb1 expression is regulated by long-range chromatin looping of an enhancer that interacts with ELF5 and SATB proteins.

2021 ◽  
Author(s):  
Fubiao Shi ◽  
Zoltan Simandi ◽  
Laszlo Nagy ◽  
Sheila Collins

AbstractIn addition to their established role to maintain blood pressure and fluid volume, the cardiac natriuretic peptides (NPs) can stimulate adipocyte lipolysis and control the brown fat gene program of nonshivering thermogenesis. The NP “clearance” receptor C (NPRC) functions to clear NPs from the circulation via peptide internalization and degradation and thus is an important regulator of NP signaling and adipocyte metabolism. It is well appreciated that the Nprc gene is highly expressed in adipose tissue and is dynamically regulated with nutrition and environmental changes. However, the molecular basis for how Nprc gene expression is regulated is still poorly understood. Here we identified Peroxisome Proliferator-Activated Receptor gamma (PPARγ) as a transcriptional regulator of Nprc expression in mouse adipocytes. During 3T3-L1 adipocyte differentiation, levels of Nprc expression increase in parallel with PPARγ induction. Rosiglitazone, a classic PPARγ agonist, increases, while siRNA knockdown of PPARγ reduces, Nprc expression in 3T3-L1 adipocytes. We demonstrate that PPARγ controls Nprc gene expression in adipocytes through its long-range distal enhancers. Furthermore, the induction of Nprc expression in adipose tissue during high-fat diet feeding is associated with increased PPARγ enhancer activity. Our findings define PPARγ as a mediator of adipocyte Nprc gene expression and establish a new connection between PPARγ and the control of adipocyte NP signaling in obesity.


Development ◽  
1998 ◽  
Vol 125 (16) ◽  
pp. 3153-3166
Author(s):  
S. Forlani ◽  
C. Bonnerot ◽  
S. Capgras ◽  
J.F. Nicolas

In the mouse, transcriptional permissiveness is established in the fertilized egg prior to the activation of zygotic genes at the 2-cell stage. Therefore, gene inactivity initiated at the end of gametogenesis results from a complex process, involving more than an inhibition of the basal transcriptional apparatus. We have examined the ability of the first intron (I1) of the human hypoxanthine phosphoribosyl transferase gene, which functions as an enhancer in embryonic stem cells, to activate a reporter gene when placed proximally to or at a distance from the HSV-tk promoter, or when integrated into the mouse genome as part of a stable transgene. In microinjected embryos, I1 functions as an enhancer sequence; however, its competence for long-range activation appears only after the late 1-cell stage and depends on the first DNA replication. Moreover, activation of microinjected transgenes from proximal enhancers occurs in the late 2-cell embryo and in the male pronucleus of 1-cell embryos blocked for DNA replication; whereas, for integrated transgenes, proximal enhancer activity is subject to position effects in the 2-cell embryo and first occurs at the 2- or 4-cell stage, but only after completion of DNA replication. Therefore, the absence of long-range activation and a non-permissive genomic state (the relief of which both depend on DNA replication), together with an inactive transcriptional apparatus, appear to converge to prevent any gene activity in the 1-cell embryo. We propose that the embryo exploits the process of DNA replication to relieve the transcriptionally repressive state that was initially established to fulfil two purposes: (1) to arrest maternal gene expression in the maturing oocyte and (2) to protect the unicellular egg and 1-cell embryo from premature differentiation. Reactivation of gene expression by DNA replication would therefore serve to coordinate cell proliferation and differentiation in the preimplantation embryo.


2019 ◽  
Vol 2019 ◽  
pp. 1-12
Author(s):  
Livia Eiselleova ◽  
Viktor Lukjanov ◽  
Simon Farkas ◽  
David Svoboda ◽  
Karel Stepka ◽  
...  

The eukaryotic nucleus is a highly complex structure that carries out multiple functions primarily needed for gene expression, and among them, transcription seems to be the most fundamental. Diverse approaches have demonstrated that transcription takes place at discrete sites known as transcription factories, wherein RNA polymerase II (RNAP II) is attached to the factory and immobilized while transcribing DNA. It has been proposed that transcription factories promote chromatin loop formation, creating long-range interactions in which relatively distant genes can be transcribed simultaneously. In this study, we examined long-range interactions between the POU5F1 gene and genes previously identified as being POU5F1 enhancer-interacting, namely, CDYL, TLE2, RARG, and MSX1 (all involved in transcriptional regulation), in human pluripotent stem cells (hPSCs) and their early differentiated counterparts. As a control gene, RUNX1 was used, which is expressed during hematopoietic differentiation and not associated with pluripotency. To reveal how these long-range interactions between POU5F1 and the selected genes change with the onset of differentiation and upon RNAP II inhibition, we performed three-dimensional fluorescence in situ hybridization (3D-FISH) followed by computational simulation analysis. Our analysis showed that the numbers of long-range interactions between specific genes decrease during differentiation, suggesting that the transcription of monitored genes is associated with pluripotency. In addition, we showed that upon inhibition of RNAP II, long-range associations do not disintegrate and remain constant. We also analyzed the distance distributions of these genes in the context of their positions in the nucleus and revealed that they tend to have similar patterns resembling normal distribution. Furthermore, we compared data created in vitro and in silico to assess the biological relevance of our results.


2019 ◽  
Vol 20 (23) ◽  
pp. 5987
Author(s):  
Suthipong Chujan ◽  
Tawit Suriyo ◽  
Jutamaad Satayavivad

Cholangiocarcinoma (CCA) is a malignant tumor originating from cholangiocyte. Prolonged alcohol consumption has been suggested as a possible risk factor for CCA, but there is no information about alcohol’s mechanisms in cholangiocyte. This study was designed to investigate global transcriptional alterations through RNA-sequencing by using chronic alcohol exposure (20 mM for 2 months) in normal human cholangiocyte MMNK-1 cells. To observe the association of alcohol induced CCA pathogenesis, we combined differentially expressed genes (DEGs) with computational bioinformatics of CCA by using publicly gene expression omnibus (GEO) datasets. For biological function analysis, Gene ontology (GO) analysis showed biological process and molecular function related to regulation of transcription from RNA polymerase II promoter, while cellular component linked to the nucleoplasm. KEGG pathway presented pathways in cancer that were significantly enriched. From KEGG result, we further examined the oncogenic features resulting in chronic alcohol exposure, enhanced proliferation, and migration through CCND-1 and MMP-2 up-regulation, respectively. Finally, combined DEGs were validated in clinical data including TCGA and immunohistochemistry from HPA database, demonstrating that FOS up-regulation was related to CCA pathogenesis. This study is the first providing more information and molecular mechanisms about global transcriptome alterations and oncogenic enhancement of chronic alcohol exposure in normal cholangiocytes.


2018 ◽  
Author(s):  
Sarada Ketharnathan ◽  
Megan Leask ◽  
James Boocock ◽  
Amanda J. Phipps-Green ◽  
Jisha Antony ◽  
...  

ABSTRACTSeveral dozen genetic variants associate with serum urate levels, but the precise molecular mechanisms by which they affect serum urate are unknown. Here we tested for functional linkage of the maximally-associated genetic variant rs1967017 at the PDZK1 locus to elevated PDZK1 expression.We performed expression quantitative trait locus (eQTL) and likelihood analyses followed by gene expression assays. Zebrafish were used to determine the ability of rs1967017 to direct tissue-specific gene expression. Luciferase assays in HEK293 and HepG2 cells measured the effect of rs1967017 on transcription amplitude.PAINTOR analysis revealed rs1967017 as most likely to be causal and rs1967017 was an eQTL for PDZK1 in the intestine. The region harboring rs1967017 was capable of directly driving green fluorescent protein expression in the kidney, liver and intestine of zebrafish embryos, consistent with a conserved ability to confer tissue-specific expression. The urate-increasing T-allele of rs1967017 strengthens a binding site for the transcription factor HNF4A. siRNA depletion of HNF4A reduced endogenous PDZK1 expression in HepG2 cells. Luciferase assays showed that the T-allele of rs1967017 gains enhancer activity relative to the urate-decreasing C-allele, with T-allele enhancer activity abrogated by HNF4A depletion. HNF4A physically binds the rs1967017 region, suggesting direct transcriptional regulation of PDZK1 by HNF4A.With other reports our data predict that the urate-raising T-allele of rs1967017 enhances HNF4A binding to the PDZK1 promoter, thereby increasing PDZK1 expression. As PDZK1 is a scaffold protein for many ion channel transporters, increased expression can be predicted to increase activity of urate transporters and alter excretion of urate.


2017 ◽  
Author(s):  
Lina Wadi ◽  
Liis Uusküla-Reimand ◽  
Keren Isaev ◽  
Shimin Shuai ◽  
Vincent Huang ◽  
...  

AbstractA comprehensive catalogue of the mutations that drive tumorigenesis and progression is essential to understanding tumor biology and developing therapies. Protein-coding driver mutations have been well-characterized by large exome-sequencing studies, however many tumors have no mutations in protein-coding driver genes. Non-coding mutations are thought to explain many of these cases, however few non-coding drivers besides TERT promoter are known. To fill this gap, we analyzed 150,000 cis-regulatory regions in 1,844 whole cancer genomes from the ICGC-TCGA PCAWG project. Using our new method, ActiveDriverWGS, we found 41 frequently mutated regulatory elements (FMREs) enriched in non-coding SNVs and indels (FDR<0.05) characterized by aging-associated mutation signatures and frequent structural variants. Most FMREs are distal from genes, reported here for the first time and also recovered by additional driver discovery methods. FMREs were enriched in super-enhancers, H3K27ac enhancer marks of primary tumors and long-range chromatin interactions, suggesting that the mutations drive cancer by distally controlling gene expression through threedimensional genome organization. In support of this hypothesis, the chromatin interaction network of FMREs and target genes revealed associations of mutations and differential gene expression of known and novel cancer genes (e.g., CNNB1IP1, RCC1), activation of immune response pathways and altered enhancer marks. Thus distal genomic regions may include additional, infrequently mutated drivers that act on target genes via chromatin loops. Our study is an important step towards finding such regulatory regions and deciphering the somatic mutation landscape of the non-coding genome.


2020 ◽  
Vol 13 (6) ◽  
Author(s):  
Amelia Weber Hall ◽  
Mark Chaffin ◽  
Carolina Roselli ◽  
Honghuang Lin ◽  
Steven A. Lubitz ◽  
...  

Background: Atrial fibrillation (AF) often arises from structural abnormalities in the left atria (LA). Annotation of the noncoding genome in human LA is limited, as are effects on gene expression and chromatin architecture. Many AF-associated genetic variants reside in noncoding regions; this knowledge gap impairs efforts to understand the molecular mechanisms of AF and cardiac conduction phenotypes. Methods: We generated a model of the LA noncoding genome by profiling 7 histone post-translational modifications (active: H3K4me3, H3K4me2, H3K4me1, H3K27ac, H3K36me3; repressive: H3K27me3, H3K9me3), CTCF binding, and gene expression in samples from 5 individuals without structural heart disease or AF. We used MACS2 to identify peak regions ( P <0.01), applied a Markov model to classify regulatory elements, and annotated this model with matched gene expression data. We intersected chromatin states with expression quantitative trait locus, DNA methylation, and HiC chromatin interaction data from LA and left ventricle. Finally, we integrated genome-wide association data for AF and electrocardiographic traits to link disease-related variants to genes. Results: Our model identified 21 epigenetic states, encompassing regulatory motifs, such as promoters, enhancers, and repressed regions. Genes were regulated by proximal chromatin states; repressive states were associated with a significant reduction in gene expression ( P <2×10 −16 ). Chromatin states were differentially methylated, promoters were less methylated than repressed regions ( P <2×10 −16 ). We identified over 15 000 LA-specific enhancers, defined by homeobox family motifs, and annotated several cardiovascular disease susceptibility loci. Intersecting AF and PR genome-wide association studies loci with long-range chromatin conformation data identified a gene interaction network dominated by NKX2-5 , TBX3 , ZFHX3 , and SYNPO2L . Conclusions: Profiling the noncoding genome provides new insights into the gene expression and chromatin regulation in human LA tissue. These findings enabled identification of a gene network underlying AF; our experimental and analytic approach can be extended to identify molecular mechanisms for other cardiac diseases and traits.


2007 ◽  
Vol 28 (3) ◽  
pp. 1081-1091 ◽  
Author(s):  
Kai Ge ◽  
Young-Wook Cho ◽  
Hong Guo ◽  
Teresa B. Hong ◽  
Mohamed Guermah ◽  
...  

ABSTRACT Mediator is a general coactivator complex connecting transcription activators and RNA polymerase II. Recent work has shown that the nuclear receptor-interacting MED1/TRAP220 subunit of Mediator is required for peroxisome proliferator-activated receptor γ (PPARγ)-stimulated adipogenesis of mouse embryonic fibroblasts (MEFs). However, the molecular mechanisms remain undefined. Here, we show an intracellular PPARγ-Mediator interaction that requires the two LXXLL nuclear receptor recognition motifs on MED1/TRAP220 and, furthermore, we show that the intact LXXLL motifs are essential for optimal PPARγ function in a reconstituted cell-free transcription system. Surprisingly, a conserved N-terminal region of MED1/TRAP220 that lacks the LXXLL motifs but gets incorporated into Mediator fully supports PPARγ-stimulated adipogenesis. Moreover, in undifferentiated MEFs, MED1/TRAP220 is dispensable both for PPARγ-mediated target gene activation and for recruitment of Mediator to a PPAR response element on the aP2 target gene promoter. However, PPARγ shows significantly reduced transcriptional activity in cells deficient for a subunit (MED24/TRAP100) important for the integrity of the Mediator complex, indicating a general Mediator requirement for PPARγ function. These results indicate that there is a conditional requirement for MED1/TRAP220 and that a direct interaction between PPARγ and Mediator through MED1/TRAP220 is not essential either for PPARγ-stimulated adipogenesis or for PPARγ target gene expression in cultured fibroblasts. As Mediator is apparently essential for PPARγ transcriptional activity, our data indicate the presence of alternative mechanisms for Mediator recruitment, possibly through intermediate cofactors or other cofactors that are functionally redundant with MED1/TRAP220.


2019 ◽  
Author(s):  
Xiao-Feng Chen ◽  
Min-Rui Guo ◽  
Yuan-Yuan Duan ◽  
Feng Jiang ◽  
Hao Wu ◽  
...  

AbstractThe genome-wide association studies (GWAS) have identified hundreds of susceptibility loci associated with autoimmune diseases. However, over 90% of risk variants are located in the noncoding regions, leading to great challenges in deciphering the underlying causal functional variants/genes and biological mechanisms. Previous studies focused on developing new scoring method to prioritize functional/disease-relevant variants. However, they principally incorporated annotation data across all cells/tissues while omitted the cell-specific or context-specific regulation. Moreover, limited analyses were performed to dissect the detailed molecular regulatory circuits linking functional GWAS variants to disease etiology. Here we devised a new analysis frame that incorporate hundreds of immune cell-specific multi-omics data to prioritize functional noncoding susceptibility SNPs with gene targets and further dissect their downstream molecular mechanisms and clinical applications for 19 autoimmune diseases. Most prioritized SNPs have genetic associations with transcription factors (TFs) binding, histone modification or chromatin accessibility, indicating their allelic regulatory roles on target genes. Their target genes were significantly enriched in immunologically related pathways and other immunologically related functions. We also detected long-range regulation on 90.7% of target genes including 132 ones exclusively regulated by distal SNPs (eg, CD28, IL2RA), which involves several potential key TFs (eg, CTCF), suggesting the important roles of long-range chromatin interaction in autoimmune diseases. Moreover, we identified hundreds of known or predicted druggable genes, and predicted some new potential drug targets for several autoimmune diseases, including two genes (NFKB1, SH2B3) with known drug indications on other diseases, highlighting their potential drug repurposing opportunities. In summary, our analyses may provide unique resource for future functional follow-up and drug application on autoimmune diseases, which are freely available at http://fngwas.online/.Author SummaryAutoimmune diseases are groups of complex immune system disorders with high prevalence rates and high heritabilities. Previous studies have unraveled thousands of SNPs associated with different autoimmune diseases. However, it remains largely unknown on the molecular mechanisms underlying these genetic associations. Striking, over 90% of risk SNPs are located in the noncoding region. By leveraging multiple immune cell-specific multi-omics data across genomic, epigenetic, transcriptomic and 3D chromatin interaction information, we systematically analyzed the functional variants/genes and biological mechanisms underlying genetic association on 19 autoimmune diseases. We found that most functional SNPs may affect target gene expression through altering transcription factors (TFs) binding, histone modification or chromatin accessibility. Most target genes had known immunological functions. We detected prevailing long-range chromatin interaction linking distal functional SNPs to target genes. We also identified many known drug targets and predicted some new drug target genes for several autoimmune diseases, suggesting their potential clinical applications. All analysis results and tools are available online, which may provide unique resource for future functional follow-up and drug application. Our study may help reduce the gap between traditional genetic findings and biological mechanistically exploration of disease etiologies as well as clinical drug development.


2017 ◽  
Author(s):  
Veronika A. Herzog ◽  
Brian Reichholf ◽  
Tobias Neumann ◽  
Philipp Rescheneder ◽  
Pooja Bhat ◽  
...  

AbstractGene expression profiling by high-throughput sequencing reveals qualitative and quantitative changes in RNA species at steady-state but obscures the intracellular dynamics of RNA transcription, processing and decay. We developed thiol(SH)-linked alkylation for the metabolic sequencing of RNA (SLAM-seq), an orthogonal chemistry-based epitranscriptomics-sequencing technology that uncovers 4-thiouridine (s4U)-incorporation in RNA species at single-nucleotide resolution. In combination with well-established metabolic RNA labeling protocols and coupled to standard, low-input, high-throughput RNA sequencing methods, SLAM-seq enables rapid access to RNA polymerase II-dependent gene expression dynamics in the context of total RNA. When applied to mouse embryonic stem cells, SLAM-seq provides global and transcript-specific insights into pluripotency-associated gene expression. We validated the method by showing that the RNA-polymerase II-dependent transcriptional output scales with Oct4/Sox2/Nanog-defined enhancer activity; and we provide quantitative and mechanistic evidence for transcript-specific RNA turnover mediated by post-transcriptional gene regulatory pathways initiated by microRNAs and N6-methyladenosine. SLAM-seq facilitates the dissection of fundamental mechanisms that control gene expression in an accessible, cost-effective, and scalable manner.One Sentence Summary:Chemical nucleotide-analog derivatization provides global insights into transcriptional and post-transcriptional gene regulation


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