Project description:We performed CITE-Seq on isolated human donor islets cultured 48hrs in the presence or absence of a cytokine cocktail. Major cell types were identified based on gene expression and changes in gene expression in beta cells were examined.
Project description:Pancreatic beta-cells are essential for survival, being the only cell type capable of insulin secretion. While they are believed to be vulnerable to damage by inflammatory cytokines such as interleukin-1 beta (IL-1beta) and IFN-gamma, we have recently identified physiological roles for cytokine signaling in rodent beta-cells that include that stimulation of antiviral and antimicrobial gene expression and the inhibition of viral replication. In this study, we examine cytokine-stimulated changes in gene expression in human islets using single-cell RNA sequencing. Surprisingly, the global responses of human islets to cytokine exposure were remarkably blunted compared to our previous observations in the mouse. The small population of human islet cells that were cytokine responsive exhibited increased expression of IL-1beta-stimulated antiviral guanylate binding proteins, just like in the mouse. Most human islet cells were not responsive to cytokines, and this lack of responsiveness was associated with high expression of genes encoding ribosomal proteins. We further correlated the expression levels of RPL5 with stress response genes, and when expressed at high levels, RPL5 is predictive of failure to respond to cytokines in all endocrine cells. Further, we postulate that donor cause of death and isolation methodologies may contribute to stress of the islet preparation. Our findings indicate that induction of stress responses in human islets (associated with isolation and/or cause of death) limit cytokine stimulated gene expression, and we urge caution in the evaluation of studies that have examined cytokine-stimulated gene expression in human islets without evaluation of stress-related gene expression.
Project description:We anticipated that the identification of cis-regulatory regions active in pancreatic islets would help increase our understanding of islet biology and the pathology of diabetes. Towards this end we used histone H3 lysine 4 monomethylation-based nucleosome predictions genome-wide, in conjunction with binding data for PDX1, FOXA2, MAFA, and NEUROD1, to identify 3,654 putative enhancers that are H3K4me1-enriched uniquely in islets as compared to 14 other tissue or cell-types. We show that these islet-specific enhancers are associated with genes with significantly higher islet specificity than genes associated with non-specific enhancers. Further, islet-specific enhancers were not enriched for typical active or repressive histone methylations in embryonic stem cells and liver, suggesting they are formed by de novo histone methylation during pancreas development. We also identify a subset of enhancers bivalently marked by both H3K4me1 and H3K27me3 in adult pancreatic islets. Further, we show that islet-specific enhancers triple- or quadruple- bound by PDX1, MAFA, NEUROD1 and/or FOXA2 are associated with genes with particularly high islet-specificity, and that these loci are enriched in regions with functional activity in islet cell types. Finally, we demonstrate that cytokines reduce H3K4me1 enrichment levels at selected triple- or quadruple-bound islet-specific enhancers, suggesting that epigenetic changes may contribute to cytokine-induced b-cell dysfunction. In conjunction with data from Hoffman et al Genome Research 2010, an analysis of histone modifications and transcription factor binding sites to identify enhancer regions
Project description:Endoplasmic reticulum (ER) and inflammatory stress responses are two pathophysiologic factors contributing to islet dysfunction and failure in Type 2 Diabetes (T2D). However, how human islet cells respond to these stressors and whether T2D-associated genetic variants modulate these responses is unknown. To fill this knowledge gap, we profiled transcriptional (RNA-seq) and epigenetic (ATAC-seq) remodeling in human islets exposed to ex vivo ER (thapsigargin) or inflammatory (IL-1β+IFN-γ) stress. 5,427 genes (~32%) were associated with stress responses; most were stressor-specific, including upregulation of genes mediating unfolded protein response (e.g. DDIT3, ATF4) and NFKB signaling (e.g. NFKB1, NFKBIA) in ER stress and cytokine-induced inflammation respectively. Islet single-cell RNA-seq profiling revealed strong but heterogeneous beta cell ER stress responses, including a distinct beta cell subset that highly expressed apoptotic genes. Epigenetic profiling uncovered 14,968 stress-responsive cis-regulatory elements (CREs; ~14%), the majority of which were stressor-specific, and revealed increased accessibility at binding sites of transcription factors that were induced upon stress (e.g. ATF4 for ER stress, IRF8 for cytokine-induced inflammation). Eighty-six stress-responsive CREs overlapped known T2D-associated variants, including 20 residing within CREs that were more accessible upon ER stress. Among these, we linked the rs6917676 T2D risk allele (T) to increased in vivo accessibility of an islet ER stress-responsive CRE and allele-specific beta cell nuclear factor binding in vitro. We showed that MAP3K5, the only ER stress-responsive gene in this locus, promotes beta cell apoptosis. Consistent with its pro-apoptotic and putative diabetogenic roles, MAP3K5 expression inversely correlated with beta cell abundance in human islets and was induced in beta cells from T2D donors. Together, this study provides new genome-wide insights into human islet stress responses and putative mechanisms of T2D genetic variants.
Project description:We found these ROS generation is regulated by lncRNA MALAT1 and genetic ablation of MALAT1 drastically reduced ROS level and oxidative stress in mouse islet cells with the benefits of improved insulin responses in MALAT1-/- mouse. The pancreatic islet consists of five cell types (α, β and γ/PP, δ and ε cells) and very little is known about the xenobiotic detoxification pathways in these cells and their sensitivity to toxicants. We utilized single-cell RNA sequencing to analyze the role of MALAT1 in regulating oxidative stress response and insulin secretion function in distinct pancreatic cell population. We also treat the isolated pancreatic islets with 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) (10 nM, 12h) to investigate the xenobiotic detoxification pathways regulation in both MALAT1 KO and WT pancreatic islets. Our result showed that a subset of genes in T2DM related pathways were significantly regulated in MALAT1 -/- β cells, with significantly unregulated INS1, INS2, and PDX1. Nrf2/detoxification pathway was also significantly activated in MALAT1 -/- β cells. In addition, MALAT1 expression level was elevated in the T2DM patients pancreatic islets cells. This study provides insights for mechanisms of regulation of oxidative stress by MALAT1-Nrf2 interaction which has the potential as a therapeutic target for the treatment of T2DM.
Project description:loss of Men1 in mouse pancreatic islet cells alters the epigenetic landscape of a subset of target genes. H3K4me3 ChIP-seq from either mouse pancreatic islets or mouse pancreatic islet tumors harvested at different stages.
Project description:We anticipated that the identification of cis-regulatory regions active in pancreatic islets would help increase our understanding of islet biology and the pathology of diabetes. Towards this end we used histone H3 lysine 4 monomethylation-based nucleosome predictions genome-wide, in conjunction with binding data for PDX1, FOXA2, MAFA, and NEUROD1, to identify 3,654 putative enhancers that are H3K4me1-enriched uniquely in islets as compared to 14 other tissue or cell-types. We show that these islet-specific enhancers are associated with genes with significantly higher islet specificity than genes associated with non-specific enhancers. Further, islet-specific enhancers were not enriched for typical active or repressive histone methylations in embryonic stem cells and liver, suggesting they are formed by de novo histone methylation during pancreas development. We also identify a subset of enhancers bivalently marked by both H3K4me1 and H3K27me3 in adult pancreatic islets. Further, we show that islet-specific enhancers triple- or quadruple- bound by PDX1, MAFA, NEUROD1 and/or FOXA2 are associated with genes with particularly high islet-specificity, and that these loci are enriched in regions with functional activity in islet cell types. Finally, we demonstrate that cytokines reduce H3K4me1 enrichment levels at selected triple- or quadruple-bound islet-specific enhancers, suggesting that epigenetic changes may contribute to cytokine-induced b-cell dysfunction.
Project description:Type 1 diabetes is an autoimmune destruction of pancreatic islet beta cell disease, and it is important to find new alternative source of the islet beta cells to replace the damaged cells. Human embryonic stem (hES) cells possess unlimited self-renewal and pluripotency and thus have the potential to provide an unlimited supply of different cell types for tissue replacement. The hES-T3 cells with normal female karyotype were first differentiated into embryoid bodies and then induced to generate the pancreatic islet-like cell clusters, which expressed pancreatic islet cell-specific markers of insulin, glucagon and somatostatin. The expression profiles of microRNAs and mRNAs from the pancreatic islet-like cell clusters were further analyzed and compared with those of undifferentiated hES-T3 cells and differentiated embryoid bodies. MicroRNAs negatively regulate the expression of protein-coding mRNAs. The pancreatic islet-like cell clusters were found to exhibit very high expression of microRNAs miR-186, miR-199a and miR-339, which down-regulated the expression of LIN28, PRDM1, CALB1, GCNT2, RBM47, PLEKHH1, RBPMS2 and PAK6. Therefore, these microRNAs are very likely to play important regulatory roles in the differentiation of pancreatic islet cells and early embryonic development. In this investigation, both miRNA and mRNA expression profiles from the pancreatic islet-like cell clusters differentiated from hES-T3 cells (T3pi) were quantitatively determined and compared with those of undifferentiated hES-T3 cells grown on mouse embryonic fibroblast (MEF) feeder (T3ES) and embryoid bodies differentiated from hES-T3 cells (T3EB). Several target genes of pancreatic islet cell-specific miRNAs were identified. ***This submission represents the mRNA expression component of the study only***
Project description:Comparative Multi-omic Mapping of Human Pancreatic Islet Endoplasmic Reticulum and Cytokine Stress Responses Provide Insights into Type 2 Diabetes Genetics