scholarly journals Differential chromatin accessibility landscape of gain-of-function mutant p53 tumours

2020 ◽  
Author(s):  
Bhavya Dhaka ◽  
Radhakrishnan Sabarinathan
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Chromatin Accessibility ◽  
Mutant P53 ◽  
Sequence Motifs ◽  
Gain Of Function ◽  
Suppressor Activity ◽  
Colon Cancers ◽  
Tumour Suppressor Activity ◽  
Novel Target

AbstractMutations in TP53 not only affect its tumour suppressor activity but also exerts oncogenic gain-of-function activity. While the genome-wide mutant p53 binding sites have been identified in cancer cell lines, the chromatin accessibility landscape driven by mutant p53 in primary tumours is unknown. Here, we leveraged the chromatin accessibility data of primary tumours from TCGA to identify differentially accessible regions in mutant p53 tumours compared to wild p53 tumours, especially in breast and colon cancers. We found 1587 lost and 984 gained accessible regions in breast, and 1143 lost and 640 gained regions in colon. However, less than half of those regions in both cancer types contain sequence motifs for wild-type or mutant p53 binding. Whereas, the remaining showed enrichment for master transcriptional regulators, such as FOX-Family TFs and NF-kB in lost and SMAD and KLF TFs in gained regions of breast. In colon, ATF3 and FOS/JUN TFs were enriched in lost, and CDX family TFs and HNF4A in gained regions. By integrating the gene expression data, we identified known and novel target genes regulated by the mutant p53. Together, these results suggest the tissue- and tumour-type specific role of mutant p53 in regulating chromatin structure and gene expression.

scholarly journals Differential chromatin accessibility landscape of gain-of-function mutant p53 tumours

BMC Cancer ◽  
2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Bhavya Dhaka ◽  
Radhakrishnan Sabarinathan
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Expression Patterns ◽  
Chromatin Accessibility ◽  
The Cancer Genome Atlas ◽  
Mutant P53 ◽  
Wild Type ◽  
Gain Of Function ◽  
Colon Cancers ◽  
The Impact

Abstract Background Mutations in TP53 not only affect its tumour suppressor activity but also exerts oncogenic gain-of-function activity. While the genome-wide mutant p53 binding sites have been identified in cancer cell lines, the chromatin accessibility landscape driven by mutant p53 in primary tumours is unknown. Here, we leveraged the chromatin accessibility data of primary tumours from The Cancer Genome Atlas (TCGA) to identify differentially accessible regions in mutant p53 tumours compared to wild-type p53 tumours, especially in breast and colon cancers. Results We identified 1587 lost and 984 gained accessible chromatin regions in breast, and 1143 lost and 640 gained regions in colon cancers. However, only less than half of those regions in both cancer types contain sequence motifs for wild-type or mutant p53 binding. Whereas, the remaining showed enrichment for master transcriptional regulators, such as FOX-Family TFs and NF-kB in lost and SMAD and KLF TFs in gained regions of breast. In colon, ATF3 and FOS/JUN TFs were enriched in lost, and CDX family TFs and HNF4A in gained regions. By integrating the gene expression data, we identified known and novel target genes regulated by the mutant p53. Conclusion This study reveals the direct and indirect mechanisms by which gain-of-function mutant p53 targets the chromatin and subsequent gene expression patterns in a tumour-type specific manner. This furthers our understanding of the impact of mutant p53 in cancer development.

scholarly journals Repurposing of KLF5 activates a cell cycle signature during the progression from a precursor state to Oesophageal Adenocarcinoma

2020 ◽  
Author(s):  
Connor Rogerson ◽  
Samuel Ogden ◽  
Edward Britton ◽  
Yeng Ang ◽  
Andrew D. Sharrocks ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Cycle ◽  
Molecular Mechanisms ◽  
Target Genes ◽  
Prognostic Significance ◽  
Gene Expression Signature ◽  
Chromatin Accessibility ◽  
Oesophageal Adenocarcinoma ◽  
Cell Cycle Gene ◽  
A Cell

AbstractOesophageal adenocarcinoma (OAC) is one of the most common causes of cancer deaths and yet compared to other common cancers, we know relatively little about the underlying molecular mechanisms. Barrett’s oesophagus (BO) is the only known precancerous precursor to OAC, but our understanding about the specific events leading to OAC development is limited. Here, we have integrated gene expression and chromatin accessibility profiles of human biopsies of BO and OAC and identified a strong cell cycle gene expression signature in OAC compared to BO. Through analysing associated chromatin accessibility changes, we have implicated the transcription factor KLF5 in the transition from BO to OAC. Importantly, we show that KLF5 expression is unchanged during this transition, but instead, KLF5 is redistributed across chromatin in OAC cells to directly regulate cell cycle genes specifically in OAC. Our findings have potential prognostic significance as the survival of patients with high expression of KLF5 target genes is significantly lower. We have provided new insights into the gene expression networks in OAC and the mechanisms behind progression to OAC, chiefly the repurposing of KLF5 for novel regulatory activity in OAC.

scholarly journals Nuclear Heparanase Regulates Chromatin Remodeling, Gene Expression and PTEN Tumor Suppressor Function

Cells ◽  
2020 ◽  
Vol 9 (9) ◽  
pp. 2038
Author(s):  
Rada Amin ◽  
Kaushlendra Tripathi ◽  
Ralph D. Sanderson
Keyword(s):  
Tumor Suppressor ◽  
Chromatin Remodeling ◽  
Target Genes ◽  
Myeloma Cell ◽  
Chromatin Accessibility ◽  
Tumor Suppressor Function ◽  
Suppressor Activity ◽  
Downstream Target ◽  
Suppressor Function ◽  
Chromatin Opening

Heparanase (HPSE) is an endoglycosidase that cleaves heparan sulfate and has been shown in various cancers to promote metastasis, angiogenesis, osteolysis, and chemoresistance. Although heparanase is thought to act predominantly extracellularly or within the cytoplasm, it is also present in the nucleus, where it may function in regulating gene transcription. Using myeloma cell lines, we report here that heparanase enhances chromatin accessibility and confirm a previous report that it also upregulates the acetylation of histones. Employing the Multiple Myeloma Research Foundation CoMMpass database, we demonstrate that patients expressing high levels of heparanase display elevated expression of proteins involved in chromatin remodeling and several oncogenic factors compared to patients expressing low levels of heparanase. These signatures were consistent with the known function of heparanase in driving tumor progression. Chromatin opening and downstream target genes were abrogated by inhibition of heparanase. Enhanced levels of heparanase in myeloma cells led to a dramatic increase in phosphorylation of PTEN, an event known to stabilize PTEN, leading to its inactivity and loss of tumor suppressor function. Collectively, this study demonstrates that heparanase promotes chromatin opening and transcriptional activity, some of which likely is through its impact on diminishing PTEN tumor suppressor activity.

scholarly journals Mutant p53 gain of function: repression of CD95(Fas/APO-1) gene expression by tumor-associated p53 mutants

Oncogene ◽  
2003 ◽  
Vol 22 (36) ◽  
pp. 5667-5676 ◽  
Author(s):  
Amir Zalcenstein ◽  
Perry Stambolsky ◽  
Lilach Weisz ◽  
Martina Müller ◽  
David Wallach ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mutant P53 ◽  
Gain Of Function

scholarly journals Modeling gene regulation from paired expression and chromatin accessibility data

2017 ◽  
Vol 114 (25) ◽  
pp. E4914-E4923 ◽  
Author(s):  
Zhana Duren ◽  
Xi Chen ◽  
Rui Jiang ◽  
Yong Wang ◽  
Wing Hung Wong
Keyword(s):  
Gene Expression ◽  
Target Genes ◽  
Transcriptional Regulatory Network ◽  
Joint Modeling ◽  
Regulatory Elements ◽  
Chromatin Accessibility ◽  
Exciting Opportunity ◽  
Transcriptional Regulatory ◽  
Dna Elements ◽  
Context Specific

The rapid increase of genome-wide datasets on gene expression, chromatin states, and transcription factor (TF) binding locations offers an exciting opportunity to interpret the information encoded in genomes and epigenomes. This task can be challenging as it requires joint modeling of context-specific activation of cis-regulatory elements (REs) and the effects on transcription of associated regulatory factors. To meet this challenge, we propose a statistical approach based on paired expression and chromatin accessibility (PECA) data across diverse cellular contexts. In our approach, we model (i) the localization to REs of chromatin regulators (CRs) based on their interaction with sequence-specific TFs, (ii) the activation of REs due to CRs that are localized to them, and (iii) the effect of TFs bound to activated REs on the transcription of target genes (TGs). The transcriptional regulatory network inferred by PECA provides a detailed view of how trans- and cis-regulatory elements work together to affect gene expression in a context-specific manner. We illustrate the feasibility of this approach by analyzing paired expression and accessibility data from the mouse Encyclopedia of DNA Elements (ENCODE) and explore various applications of the resulting model.

scholarly journals Integrative Omics analyses reveal epigenetic memory in diabetic renal cells regulating genes associated with kidney dysfunction.

2020 ◽  
Author(s):  
Ada Admin ◽  
Anita Bansal ◽  
Sreeram Balasubramanian ◽  
Sangeeta Dhawan ◽  
Amy Leung ◽  
...  
Keyword(s):  
Gene Expression ◽  
Dna Methylation ◽  
Target Genes ◽  
Major Complication ◽  
Promoter Hypermethylation ◽  
Chromatin Accessibility ◽  
Metabolic Memory ◽  
Epigenetic Memory ◽  
Motif Analysis

Diabetic kidney disease (DKD) is a major complication of diabetes and the leading cause of end-stage renal failure. Epigenetics has been associated with metabolic memory, in which prior periods of hyperglycemia enhance the future risk of developing DKD despite subsequent glycemic control. To understand the mechanistic role of such epigenetic memory in human DKD and identify new therapeutic targets, we profiled gene expression, DNA methylation, and chromatin accessibility in kidney proximal tubule epithelial cells (PTECs) derived from non-diabetic and Type-2 diabetic (T2D) subjects. T2D-PTECs displayed persistent gene expression and epigenetic changes with and without TGFβ1 treatment, even after culturing <i>in vitro</i> under similar conditions as non-diabetic PTECs, signified by deregulation of fibrotic and transport associated genes (TAGs). Motif-analysis of differential DNA methylation and chromatin accessibility regions associated with genes differentially regulated in T2D revealed enrichment for SMAD3, HNF4A, and CTCF transcription factor binding sites. Furthermore, the downregulation of several TAGs in T2D (including <i>CLDN10</i>, <i>CLDN14</i>, <i>CLDN16</i>, <i>SLC16A2</i>, <i>SLC16A5</i>) was associated with promoter hypermethylation, decreased chromatin accessibility and reduced enrichment of HNF4A, histone H3-lysine-27-acetylation, and CTCF. Together, these integrative analyses reveal epigenetic memory underlying the deregulation of key target genes in T2D-PTECs that may contribute to sustained renal dysfunction in DKD.

scholarly journals Chromosome 1q amplification perturbs a ceRNA network to promote melanoma metastasis

2021 ◽  
Author(s):  
Xiaonan Xu ◽  
Kaizhen Wang ◽  
Olga Vera ◽  
Akanksha Verma ◽  
Olivier Elemento ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cancer Progression ◽  
Target Genes ◽  
Melanoma Metastasis ◽  
Dependent Manner ◽  
Suppressor Activity ◽  
Protein Coding ◽  
Chromosome 1Q ◽  
Cerna Network ◽  
Melanoma Progression

Deregulated gene expression through epigenetic, transcriptional, and copy number alterations is a major driver of melanoma progression and metastasis. In addition to serving as blueprints for translation, some mRNAs post-transcriptionally regulate gene expression by competitively sequestering miRNAs they share with other targets. Here we report that such mRNAs, termed competitive endogenous RNAs (ceRNAs), contribute to melanoma progression and metastasis. ceRNA predictions identified multiple candidate genes on chromosome 1q, which is recurrently amplified in melanoma. Genetic studies reveal that three of these mRNAs, CEP170, NUCKS1, and ZC3H11A, promote melanoma migration, invasion, and metastasis in a protein coding-independent and miRNA binding site-dependent manner. Interestingly, CEP170, NUCKS1, and ZC3H11A cooperate to elicit oncogenic effects by collectively impairing the tumor suppressor activity of 8 miRNAs on several pro-metastatic target genes. Finally, this complex chromosome 1q ceRNA network is evident in other cancer types, suggesting ceRNA network deregulation is a common driver of cancer progression.

scholarly journals PyBoost: A parallelized Python implementation of 2D boosting with hierarchies

2017 ◽  
Author(s):  
Peyton G. Greenside ◽  
Nadine Hussami ◽  
Jessica Chang ◽  
Anshul Kundaje
Keyword(s):  
Gene Expression ◽  
Regulatory Networks ◽  
Stem Cell Differentiation ◽  
Cell Types ◽  
Chromatin Accessibility ◽  
Sequence Motifs ◽  
Specific Sequence ◽  
Tail Regeneration ◽  
Perturbation Data ◽  
Time Courses

AbstractMotivation:Gene expression is controlled by networks of transcription factors that bind specific sequence motifs in regulatory DNA elements such as promoters and enhancers. GeneClass is a boosting-based algorithm that learns gene regulatory networks from complementary paired feature sets such as transcription factor expression levels and binding motifs across conditions. This algorithm can be used to predict functional genomics measures of cell state, such as gene expression and chromatin accessibility, in different cellular conditions. We present a parallelized, Python-based implementation of GeneClass, called PyBoost, along with a novel hierarchical implementation of the algorithm, called HiBoost. HiBoost allows regulatory logic to be constrained to a hierarchical group of conditions or cell types. The software can be used to dissect differentiation cascades, time courses or other perturbation data that naturally form a hierarchy or trajectory. We demonstrate the application of PyBoost and HiBoost to learn regulators of tadpole tail regeneration and hematopoeitic stem cell differentiation and validate learned regulators through an inducible CRISPR system.Availability:The implementation is publicly available here:https://github.com/kundajelab/boosting2D/.

FLT3ITD Target Enhancers Are Primed but Inaccessible in Fetal Hematopoietic Progenitors

Blood ◽  
2019 ◽  
Vol 134 (Supplement_1) ◽  
pp. 1228-1228
Author(s):  
Yanan Li ◽  
Riddhi M Patel ◽  
Emily Casey ◽  
Jeffrey A. Magee
Keyword(s):  
Gene Expression ◽  
Transcription Factors ◽  
Target Gene ◽  
Target Genes ◽  
Conflicts Of Interest ◽  
Gene Activation ◽  
Chromatin Accessibility ◽  
Luciferase Reporter ◽  
Enhancer Activity ◽  
Target Gene Expression

The FLT3 Internal Tandem Duplication (FLT3ITD) is common somatic mutation in acute myeloid leukemia (AML). We have previously shown that FLT3ITD fails to induce changes in HSC self-renewal, myelopoiesis and leukemogenesis during fetal stages of life. FLT3ITD signal transduction pathways are hyperactivated in fetal progenitors, but FLT3ITD target genes are not. This suggests that postnatal-specific transcription factors may be required to help induce FLT3ITD target gene expression. Alternatively, repressive histone modifications may impose a barrier to FLT3ITD target gene activation in fetal HPCs that is relaxed during postnatal development. To resolve these possibilities, we used ATAC-seq, as well as H3K4me1, H3K27ac and H3K27me3 ChIP-seq, to identify cis-elements that putatively control FLT3ITD target gene expression in fetal and adult hematopoietic progenitor cells (HPCs). We identified many enhancer elements (ATAC-seq peaks with H3K4me1 and H3K27ac) that exhibited increased chromatin accessibility and activity in FLT3ITD adult HPCs relative to wild type adult HPCs. These elements were enriched near FLT3ITD target genes. HOMER analysis showed enrichment for STAT5, ETS, RUNX1 and IRF binding motifs within the FLT3ITD target enhancers, but motifs for temporally dynamic transcription factors were not identified. We cloned a subset of the enhancers and confirmed that they could synergize with their promoter to activate a luciferase reporter. For representative enhancers, STAT5 binding sites were required to activate the enhancer - as anticipated - and RUNX1 repressed enhancer activity. We tested whether accessibility or priming changed between fetal and adult stages of HPC development. FLT3ITD-dependent changes in chromatin accessibility were not observed in fetal HPCs, though the enhancers were primed early in development as evidenced by the presence of H3K4me1. Repressive H3K27me3 were not present at FLT3ITD target enhancers in either or adult HPCs. The data show that FLT3ITD target enhancers are demarcated early in hematopoietic development, long before they become responsive to FLT3ITD signaling. Repressive marks do not appear to create an epigenetic barrier to enhancer activation in the fetal stage. Instead, age-specific transcription factors are likely required to pioneer enhancer elements so that they can respond to STAT5 and other FLT3ITD effectors. Disclosures No relevant conflicts of interest to declare.

Sign in / Sign up

Export Citation Format

Share Document