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Integration of ATAC-seq and RNA-seq identifies human alpha cell and beta cell signature genes.

ABSTRACT: Although glucagon-secreting ?-cells and insulin-secreting ?-cells have opposing functions in regulating plasma glucose levels, the two cell types share a common developmental origin and exhibit overlapping transcriptomes and epigenomes. Notably, destruction of ?-cells can stimulate repopulation via transdifferentiation of ?-cells, at least in mice, suggesting plasticity between these cell fates. Furthermore, dysfunction of both ?- and ?-cells contributes to the pathophysiology of type 1 and type 2 diabetes, and ?-cell de-differentiation has been proposed to contribute to type 2 diabetes. Our objective was to delineate the molecular properties that maintain islet cell type specification yet allow for cellular plasticity. We hypothesized that correlating cell type-specific transcriptomes with an atlas of open chromatin will identify novel genes and transcriptional regulatory elements such as enhancers involved in ?- and ?-cell specification and plasticity.We sorted human ?- and ?-cells and performed the "Assay for Transposase-Accessible Chromatin with high throughput sequencing" (ATAC-seq) and mRNA-seq, followed by integrative analysis to identify cell type-selective gene regulatory regions.We identified numerous transcripts with either ?-cell- or ?-cell-selective expression and discovered the cell type-selective open chromatin regions that correlate with these gene activation patterns. We confirmed cell type-selective expression on the protein level for two of the top hits from our screen. The "group specific protein" (GC; or vitamin D binding protein) was restricted to ?-cells, while CHODL (chondrolectin) immunoreactivity was only present in ?-cells. Furthermore, ?-cell- and ?-cell-selective ATAC-seq peaks were identified to overlap with known binding sites for islet transcription factors, as well as with single nucleotide polymorphisms (SNPs) previously identified as risk loci for type 2 diabetes.We have determined the genetic landscape of human ?- and ?-cells based on chromatin accessibility and transcript levels, which allowed for detection of novel ?- and ?-cell signature genes not previously known to be expressed in islets. Using fine-mapping of open chromatin, we have identified thousands of potential cis-regulatory elements that operate in an endocrine cell type-specific fashion.

SUBMITTER: Ackermann AM

PROVIDER: S-EPMC4770267 | biostudies-literature | 2016 Mar

REPOSITORIES: biostudies-literature

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Project description:Objective: Although glucagon-secreting Î±-cells and insulin-secreting Î²-cells have opposing functions in regulating plasma glucose levels, the two cell types share a common developmental origin and have overlaps in their transcriptome and epigenome profiles. Notably, destruction of one of these cell populations can stimulate repopulation via transdifferentiation of the other cell type, at least in mice, suggesting plasticity between these cell fates. Furthermore, dysfunction of both Î±- and Î²-cells contributes to the pathophysiology of type 1 and type 2 diabetes, and Î²-cell de-differentiation has been proposed to contribute to type 2 diabetes. Our objective was to delineate the molecular properties that maintain islet cell type specification yet allow for cellular plasticity. We hypothesized that correlating cell type-specific transcriptomes with an atlas of open chromatin will identify novel genes and transcriptional regulatory elements such as enhancers involved in Î±- and Î²-cell specification and plasticity. Methods: We sorted human a- and b-cells and performed the â??Assay for Transposase-Accessible Chromatin with high throughput sequencingâ?? (ATAC-seq) and mRNA-seq, followed by integrative analysis to identify cell type-selective gene regulatory regions. Results: We identified numerous transcripts with either Î±-cell- or Î²-cell-selective expression and discovered the cell type-selective open chromatin regions that correlate with these gene activation patterns. We confirmed cell type-selective expression on the protein level for two of the top hits from our screen. The â??group specific proteinâ?? (GC; or vitamin D binding protein) was restricted to a-cells, while CHODL (chondrolectin) immunoreactivity was only present in b-cells. Furthermore, Î±-cell- and Î²-cell-selective ATAC-seq peaks were identified to overlap with known binding sites for islet transcription factors, as well as with common single nucleotide polymorphisms (SNPs) previously identified as risk loci for type 2 diabetes. Conclusions: We have determined the genetic landscape of human Î±- and Î²-cells based on chromatin accessibility and transcript levels, which allowed for detection of novel Î±- and Î²-cell signature genes not previously known to be expressed in islets. Using fine-mapping of open chromatin, we have identified thousands of potential cis-regulatory elements that operate in an endocrine cell type-specific fashion. ATAC-seq on 3 human alpha cell samples, 3 human beta cell samples, and 2 human acinar cell samples. RNA-seq on 7 human alpha cell samples and 8 human beta cell samples.

Project description:Meat quality is one of the most important economic traits in pig breeding and production, and intramuscular fat (IMF) content is the major factor in improving meat quality. The IMF deposition in pigs is influenced by transcriptional regulation, which is dependent on chromatin accessibility. However, how chromatin accessibility plays a regulatory role in IMF deposition in pigs has not been reported. Xidu black is a composite pig breed with excellent meat quality, which is an ideal research object of this study. In this study, we used the assay for transposase-accessible chromatin using sequencing (ATAC-seq) and RNA sequencing (RNA-seq) analysis to identify the accessible chromatin regions and key genes affecting IMF content in Xidu black pig breed with extremely high and low IMF content. First, we identified 21,960 differential accessible chromatin peaks and 297 differentially expressed genes. The motif analysis of differential peaks revealed several potential cis-regulatory elements containing binding sites for transcription factors with potential roles in fat deposition, including Mef2c, CEBP, Fra1, and AP-1. Then, by integrating the ATAC-seq and RNA-seq analysis results, we found 47 genes in the extremely high IMF (IMF_H) group compared with the extremely low IMF (IMF_L) group. For these genes, we observed a significant positive correlation between the differential gene expression and differential ATAC-seq signal (r 2 = 0.42). This suggests a causative relationship between chromatin remodeling and the resulting gene expression. We identified several candidate genes (PVALB, THRSP, HOXA9, EEPD1, HOXA10, and PDE4B) that might be associated with fat deposition. Through the PPI analysis, we found that PVALB gene was the top hub gene. In addition, some pathways that might regulate fat cell differentiation and lipid metabolism, such as the PI3K-Akt signaling pathway, MAPK signaling pathway, and calcium signaling pathway, were significantly enriched in the ATAC-seq and RNA-seq analysis. To the best of our knowledge, our study is the first to use ATAC-seq and RNA-seq to examine the mechanism of IMF deposition from a new perspective. Our results provide valuable information for understanding the regulation mechanism of IMF deposition and an important foundation for improving the quality of pork.

Project description:Objective: Although glucagon-secreting α-cells and insulin-secreting β-cells have opposing functions in regulating plasma glucose levels, the two cell types share a common developmental origin and have overlaps in their transcriptome and epigenome profiles. Notably, destruction of one of these cell populations can stimulate repopulation via transdifferentiation of the other cell type, at least in mice, suggesting plasticity between these cell fates. Furthermore, dysfunction of both α- and β-cells contributes to the pathophysiology of type 1 and type 2 diabetes, and β-cell de-differentiation has been proposed to contribute to type 2 diabetes. Our objective was to delineate the molecular properties that maintain islet cell type specification yet allow for cellular plasticity. We hypothesized that correlating cell type-specific transcriptomes with an atlas of open chromatin will identify novel genes and transcriptional regulatory elements such as enhancers involved in α- and β-cell specification and plasticity. Methods: We sorted human a- and b-cells and performed the “Assay for Transposase-Accessible Chromatin with high throughput sequencing” (ATAC-seq) and mRNA-seq, followed by integrative analysis to identify cell type-selective gene regulatory regions. Results: We identified numerous transcripts with either α-cell- or β-cell-selective expression and discovered the cell type-selective open chromatin regions that correlate with these gene activation patterns. We confirmed cell type-selective expression on the protein level for two of the top hits from our screen. The “group specific protein” (GC; or vitamin D binding protein) was restricted to a-cells, while CHODL (chondrolectin) immunoreactivity was only present in b-cells. Furthermore, α-cell- and β-cell-selective ATAC-seq peaks were identified to overlap with known binding sites for islet transcription factors, as well as with common single nucleotide polymorphisms (SNPs) previously identified as risk loci for type 2 diabetes. Conclusions: We have determined the genetic landscape of human α- and β-cells based on chromatin accessibility and transcript levels, which allowed for detection of novel α- and β-cell signature genes not previously known to be expressed in islets. Using fine-mapping of open chromatin, we have identified thousands of potential cis-regulatory elements that operate in an endocrine cell type-specific fashion.

Project description:BackgroundGlioblastoma multiforme (GBM) is a highly lethal, stage IV brain tumour with a prevalence of approximately 2 per 10,000 people globally. The cell surface proteins or surfaceome serve as information gateway in many oncogenic signalling pathways and are important in modulating cancer phenotypes. Dysregulation in surfaceome expression and activity have been shown to promote tumorigenesis. The expression of GBM surfaceome is a case in point; OMICS screening in a cell-based system identified that this sub-proteome is largely perturbed in GBM. Additionally, since these cell surface proteins have 'direct' access to drugs, they are appealing targets for cancer therapy. However, a comprehensive GBM surfaceome landscape has not been fully defined yet. Thus, this study aimed to define GBM-associated surfaceome genes and identify key cell-surface genes that could potentially be developed as novel GBM biomarkers for therapeutic purposes.MethodsWe integrated the RNA-Seq data from TCGA GBM (n = 166) and GTEx normal brain cortex (n = 408) databases to identify the significantly dysregulated surfaceome in GBM. This was followed by an integrative analysis that combines transcriptomics, proteomics and protein-protein interaction network data to prioritize the high-confidence GBM surfaceome signature.ResultsOf the 2381 significantly dysregulated genes in GBM, 395 genes were classified as surfaceome. Via the integrative analysis, we identified 6 high-confidence GBM molecular signature, HLA-DRA, CD44, SLC1A5, EGFR, ITGB2, PTPRJ, which were significantly upregulated in GBM. The expression of these genes was validated in an independent transcriptomics database, which confirmed their upregulated expression in GBM. Importantly, high expression of CD44, PTPRJ and HLA-DRA is significantly associated with poor disease-free survival. Last, using the Drugbank database, we identified several clinically-approved drugs targeting the GBM molecular signature suggesting potential drug repurposing.ConclusionsIn summary, we identified and highlighted the key GBM surface-enriched repertoires that could be biologically relevant in supporting GBM pathogenesis. These genes could be further interrogated experimentally in future studies that could lead to efficient diagnostic/prognostic markers or potential treatment options for GBM.

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Integration of ATAC-seq and RNA-seq identifies human alpha cell and beta cell signature genes.

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