Project description:We have studied the impact of T2D on open chromatin in human pancreatic islets. We used assay for transposase-accessible chromatin using sequencing (ATAC-seq) to profile open chromatin in islets from T2D and non-diabetic donors. We identified ATAC-seq peaks representing open chromatin regions in islets of non-diabetic and diabetic donors. The majority of ATAC-seq peaks mapped near transcription start sites. Additionally, peaks were enriched in enhancer regions and in regions where islet-specific TFs bind. Islet ATAC-seq peaks overlap with SNPs associated with T2D and with additional SNPs in LD with known T2D SNPs. There was enrichment of open chromatin regions near highly expressed genes in human islets.
Project description:Identifying cis-regulatory elements is important to understand how human pancreatic islets modulate gene expression in physiologic or pathophysiologic (e.g., diabetic) conditions. We conducted genome-wide analysis of DNase I hypersensitive sites, histone H3 lysine methylation marks (K4me1, K4me3, K79me2), and CCCTC factor (CTCF) binding in human islets. This identified ~18,000 putative promoters (several hundred novel and islet-active). Surprisingly, active promoter marks were absent at genes encoding islet-specific hormones, suggesting a distinct regulatory mechanism. Of 34,039 distal (non-promoter) regulatory elements, 47% are islet-unique and 22% are CTCF-bound. These findings present a global snapshot of the human islet epigenome and should provide functional context for non-coding variants emerging from genetic studies of T2D and other pancreatic islet disorders. Three different islet samples were tested for DNase I hypersensitivity by DNase-Seq. Five different primary pancreatic islet samples were evaluated for several chromatin modifications (H3K4me3, H3K4me1, H3K79me2) by ChIP-seq. One islet sample was evaluated for CTCF binding via ChIP-seq, All ChIP-seq samples have both non-specific IP (GFP) and input DNA controls.
Project description:We used single cell multiome (ATAC and RNA) sequencing to profile 85266 islet cells from 20 individuals, including islets from non-diabetic, pre-diabetic and type 2 diabetic (T2D) donors. We characterize changes in regulatory programs of islet cell types and subtypes in T2D progression, describe the relationship of these programs to genetic risk for T2D, and use allelic imbalance mapping to define cell type-specific functions for candidate T2D causal variants.
2023-02-07 | GSE200044 | GEO
Project description:ATAC-seq in pancreatic islet cells
Project description:RNA-seq data obtained from directed differentiation of a subset of FiPSCs and BiPSCs cell lines towards islet-like cells. RNA was collected at two key developmental stages: definitive endoderm (DE) and pancreatic progenitors (PP).
Project description:In this study, we used single cell nucleus ATAC-seq (snATAC-seq) to profile 218,973 islet cells from 34 individuals, including islets from non-diabetic, pre-diabetic and type 2 diectic (T2D) donors. We characterize changes in regulatory programs of islet cell types in T2D progression, describe the relationship of these programs to genetic risk for T2D, and use allelic imbalance mapping to define cell type-specific functions for candidate T2D causal variants.
Project description:Transgenic mice were generated that expressed the inhibitor of apoptosis and mitotic regulator survivin in pancreatic islet beta cells. Control non-transgenic or transgenic islets were then used in a model of islet transplantation in diabetic recipient mice and tested for their ability to correct hyperglycemia and allow long-term engraftment of tranplanted islets in vivo. Control or transgenic islets were analyzed by chip microarray for potential transcriptional changes associated with transgenic expression of survivin, in vivo.
Project description:Identifying cis-regulatory elements is important to understand how human pancreatic islets modulate gene expression in physiologic or pathophysiologic (e.g., diabetic) conditions. We conducted genome-wide analysis of DNase I hypersensitive sites, histone H3 lysine methylation marks (K4me1, K4me3, K79me2), and CCCTC factor (CTCF) binding in human islets. This identified ~18,000 putative promoters (several hundred novel and islet-active). Surprisingly, active promoter marks were absent at genes encoding islet-specific hormones, suggesting a distinct regulatory mechanism. Of 34,039 distal (non-promoter) regulatory elements, 47% are islet-unique and 22% are CTCF-bound. These findings present a global snapshot of the human islet epigenome and should provide functional context for non-coding variants emerging from genetic studies of T2D and other pancreatic islet disorders.
Project description:To gain further insight into potential specific gene signatures expressed by pancreatic islet cells and pathogenic CD4+ T lymphocytes isolated from sublines of non-obese diabetic (NOD) mice expressing high or low autoimmune (type 1) diabetes incidence.
Project description:Blood glucose levels are tightly controlled by the coordinated action of at least five cell types constituting pancreatic islets. Changes in the proportion and/or function of these cells are associated with genetic and molecular pathophysiology of monogenic, type 1, and type 2 diabetes (T2D). Cellular heterogeneity impedes precise understanding of the molecular components of each islet cell type that govern islet dysfunction, particularly the less abundant delta and gamma/pancreatic polypeptide (PP) cells. Here, we report single cell transcriptomes for 617 islet cells after profiling ~1000 cells from non-diabetic (ND) and T2D human organ donors. Analyses of non-diabetic single cell transcriptomes identified distinct alpha, beta, delta, and PP/gamma cell-type signatures. Genes linked to rare and common forms of islet dysfunction and diabetes were expressed in the delta and PP/gamma cell types. Moreover, this study revealed that delta cells specifically express receptors that receive and coordinate systemic cues from the leptin, ghrelin, and dopamine signaling pathways implicating them as integrators of central and peripheral metabolic signals into the pancreatic islet. Finally, single cell transcriptome profiling revealed genes differentially regulated between T2D and ND alpha, beta, and delta cells that were undetectable in paired whole islet analyses. This study thus identifies fundamental cell type-specific features of pancreatic islet (dys)function and provides a critical resource for comprehensive understanding of islet biology and diabetes pathogenesis. Grant ID: Award No. W81XWH-16-1-0130 Grant title: Peer Reviewed Medical Research Program Funding Source: Assistant Secretary of Defense for Health Affairs Affiliation: Jackson Laboratory for Genomic Medicine, Farmington, CT Name: Michael Stitzel