Mapping of INS promoter interactions reveals its role in long-range regulation of SYT8 transcription
ABSTRACT: Insulin (INS) synthesis and secretion from pancreatic β cells are tightly regulated; their deregulation causes diabetes. Here we map INS-associated loci in human pancreatic islets by 4C and 3C techniques and show that the INS gene physically interacts with the SYT8 gene, located over 300 kb away. This interaction is elevated by glucose and accompanied by increases in SYT8 expression. Inactivation of the INS promoter by promoter-targeting siRNA reduces SYT8 gene expression. SYT8-INS interaction and SYT8 transcription are attenuated by CTCF depletion. Furthermore, SYT8 knockdown decreases insulin secretion in islets. These results reveal a non-redundant role for SYT8 in insulin secretion and indicate that the INS promoter acts from a distance to stimulate SYT8 transcription. This suggests a function for the INS promoter in coordinating insulin transcription and secretion through long-range regulation of SYT8 expression in human islets. Overall design: Circular Chromosome Conformation Capture (4C)-Seq experiments to profile interactions of INS promoter in human pancreatic islets isolated from two donors: donor 1 and donor 2.
Project description:Insulin (INS) synthesis and secretion from pancreatic β cells are tightly regulated; their deregulation causes diabetes. Here we map INS-associated loci in human pancreatic islets by 4C and 3C techniques and show that the INS gene physically interacts with the SYT8 gene, located over 300 kb away. This interaction is elevated by glucose and accompanied by increases in SYT8 expression. Inactivation of the INS promoter by promoter-targeting siRNA reduces SYT8 gene expression. SYT8-INS interaction and SYT8 transcription are attenuated by CTCF depletion. Furthermore, SYT8 knockdown decreases insulin secretion in islets. These results reveal a non-redundant role for SYT8 in insulin secretion and indicate that the INS promoter acts from a distance to stimulate SYT8 transcription. This suggests a function for the INS promoter in coordinating insulin transcription and secretion through long-range regulation of SYT8 expression in human islets. Circular Chromosome Conformation Capture (4C)-Seq experiments to profile interactions of INS promoter in human pancreatic islets isolated from two donors: donor 1 and donor 2.
Project description:To systematically examine the cellular identity of INS+ cells derived after H1152 treatment, INSw/GFP HES3 hESCs were differentiated to a pancreatic progenitor population and treated with 10 µM H1152 for 8 days in sphere culture. The INS-GFP+ cells of H1152 or DMSO treated spheres were purified by cell sorting and transcripts profiled using RNA-seq. Overall design: The INS-GFP+ cells of H1152 or DMSO treated spheres were purified by cell sorting and transcripts profiled using RNA-seq. Rat insulin promoter driven ZsGreen-sorted beta cells from human islets were also assayed.
Project description:Using an integrated approach to characterize the pancreatic tissue and isolated islets from a 33-year-old with 17 years of type 1 diabetes (T1D), we found donor islets contained β cells without insulitis and lacked glucose-stimulated insulin secretion despite a normal insulin response to cAMP-evoked stimulation. With these unexpected findings for T1D, we sequenced the donor DNA and found a pathogenic heterozygous variant in hepatocyte nuclear factor 1 alpha (HNF1A). In one of the first studies of human pancreatic islets with a disease-causing HNF1A variant associated with the most common form of monogenic diabetes, we found that HNF1A dysfunction leads to insulin-insufficient diabetes reminiscent of T1D by impacting the regulatory processes critical for glucose-stimulated insulin secretion and suggest a rationale for a therapeutic alternative to current treatment. Overall design: Total of 12 samples were analyzed, 10 were non-diabetic control donors and 2 were HNF1A donors. GEO accession number for non-diabetic controls are GSE116559(β cell controls) and GSE106148 (α cell controls). α cells and β cells were FACS-sorted and RNA was extracted from each of these samples. RNAseq was performed on all 12 samples
Project description:Human pluripotent stem cells (hPSCs) have the potential to generate any human cell type, and one widely recognized goal is to make pancreatic β cells. To this end, comparisons between differentiated cell types produced in vitro and their in vivo counterparts are essential to validate hPSC-derived cells. Genome-wide transcriptional analysis of sorted insulin-expressing (INS(+)) cells derived from three independent hPSC lines, human fetal pancreata, and adult human islets points to two major conclusions: (i) Different hPSC lines produce highly similar INS(+) cells and (ii) hPSC-derived INS(+) (hPSC-INS(+)) cells more closely resemble human fetal β cells than adult β cells. This study provides a direct comparison of transcriptional programs between pure hPSC-INS(+) cells and true β cells and provides a catalog of genes whose manipulation may convert hPSC-INS(+) cells into functional β cells RNA is isolated and processed using MARIS from the following samples: H1 human embryonic stem cells (hESCs) in duplicate, HUES8 hESCs in duplicate, human induced pluripotent stem cells (hiPSCs) in duplicate, H1 cells differentiated to a stage in which insulin-expressing cells are present (stage 6) in duplicate, HUES8 cells differentiated to stage 6 in duplicate, hiPSCs differentiated to stage 6, insulin-expressing cells sorted from H1 cells differentiated to stage 6 in duplicate, insulin-expressing cells sorted from HUES8 cells differentiated to stage 6 in duplicate, insulin-expressing cells sorted from hiPSCs differentiated to stage 6 in duplicate, human week 16 fetal pancreata in duplicate, insulin-expressing cells sorted from human week 16 fetal pancreata in triplicate, adult human pancreatic islets in triplicate, and insulin-expressing cells sorted from adult human pancreatic islets in triplicate.
Project description:Displacement of Bromodomain and Extra-Terminal (BET) proteins from chromatin has promise for cancer and inflammatory disease treatments, but roles of BET proteins in metabolic disease remain unexplored. Small molecule BET inhibitors, such as JQ1, block BET protein binding to acetylated lysines, but lack selectivity within the BET family (Brd2, Brd3, Brd4, Brdt), making it difficult to disentangle contributions of each family member to transcriptional and cellular outcomes. Here, we demonstrate multiple improvements in pancreatic β-cells upon BET inhibition with JQ1 or BET-specific siRNAs. JQ1 (50-400 nM) increases insulin secretion from INS-1 cells in a concentration dependent manner. JQ1 increases insulin content in INS-1 cells, accounting for increased secretion, in both rat and human islets. Higher concentrations of JQ1 decrease intracellular triglyceride stores in INS-1 cells, a result of increased fatty acid oxidation. Specific inhibition of both Brd2 and Brd4 enhances insulin transcription, leading to increased insulin content. Inhibition of Brd2 alone increases fatty acid oxidation. Overlapping yet discrete roles for individual BET proteins in metabolic regulation suggest new isoform-selective BET inhibitors may be useful to treat insulin resistant/diabetic patients. Results imply that cancer and diseases of chronic inflammation or disordered metabolism are related through shared chromatin regulatory mechanisms. Overall design: BET proteins are not redundant in their functions, thus pan-BET inhibitors like JQ1 cannot properly be interpreted without specific RNA knockdown or small molecules of proven selectivity. Here, we expose INS-1 cells, a rat insulinoma model for the pancreatic beta cell, to selective siRNAs to ablate Brd2, Brd3 or Brd4 mRNAs and compared genome-wide changes in transcription to non-targeted siRNA control. As expected, three resolvably different patterns of gene expression were identified, establishing that each BET protein controls its own set of target genes.
Project description:The short chain fatty acid (SCFA) receptor (free fatty acid receptor-3; FFAR3) is expressed in pancreatic beta cells; however, its role in insulin secretion is not clearly defined. Here, we examined the role of FFAR3 in insulin secretion. Using islets from global knockout FFAR3 (Ffar3-/-) mice, we explored the role of FFAR3 and ligand-induced FFAR3 signaling on glucose stimulated insulin secretion. RNA sequencing was also performed to gain greater insight into the impact of FFAR3 deletion on the islet transcriptome. First exploring insulin secretion, it was determined that Ffar3-/- islets secrete more insulin in a glucose-dependent manner as compared to wildtype (WT) islets. Next, exploring its primary endogenous ligand, propionate, and a specific agonist for FFAR3, signaling by FFAR3 inhibited glucose-dependent insulin secretion, which occurred through a Gαi/o pathway. To help understand these results, transcriptome analyses by RNA-sequencing of Ffar3-/- and WT islets observed multiple genes with well known roles in islet biology to be altered by genetic knockout of FFAR3. Our data shows that FFAR3 signaling mediates glucose stimulated insulin secretion through Gαi/o sensitive pathway. Future studies are needed to more rigorously define the role of FFAR3 by in vivo approaches. Analysis of total RNA from 3 biological replicates of pancreatic islets isolated from free fatty acid receptor 3 knockout (Ffar3 KO) and wildtype (Ffar3 WT) male mice
Project description:Differentiation of INSGFP/w hESCs using published protocols demonstrated that all GFP+ cells co-expressed insulin, confirming the fidelity of the reporter gene. INS-GFP+ cells also co-expressed glucagon and somatostatin, confirming prior studies regarding the polyhormonal nature of early hESC derived insulin-expressing cells. INSGFP/w hESCs were employed to develop a 96 well format spin Embryoid Body (EB) differentiation protocol that utilized the recombinant protein based fully defined medium, APEL. Like INS-GFP+ cells generated with other methods, those derived using the spin EB protocol expressed a collection of pancreatic related transcription factors including ISL1, PAX6 and NKX2.2. However, in contrast to previous methods, the spin EB protocol yielded INS-GFP+ cells that also co-expressed the beta-cell transcription factor, NKX6.1 and comprised a substantial proportion of monohormonal insulin+ cells.
Project description:UDP-sugars were identified as extracellular signaling molecules, assigning a new function to these compounds in addition to their well defined role in intracellular substrate metabolism and storage. Previously regarded as an orphan receptor, the G protein-coupled receptor (GPCR) P2Y14 (GPR105) was found to bind extracellular UDP and UDP-sugars. Little is known about the physiological functions of this GPCR. To study its physiological role we used a gene-deficient (KO) mouse strain expressing the bacterial LacZ reporter gene to monitor the physiological expression pattern of P2Y14. We found that P2Y14 is mainly expressed in pancreas and salivary glands and in subpopulations of smooth muscle cells of the gastrointestinal tract, blood vessels, lung and uterus. Among other phenotypical differences KO mice showed a significantly impaired glucose tolerance following oral and intraperitoneal glucose application. An unchanged insulin tolerance suggested altered pancreatic islet function. Transcriptome analysis of pancreatic islets showed that P2Y14 deficiency significantly changed expression of components involved in insulin secretion. Insulin secretion tests revealed a reduced insulin release from P2Y14-deficient islets highlighting P2Y14 as a new modulator of proper insulin secretion. 10 samples from pancreatic islets isolated from wildtype mice; 10 samples from pancreatic islets isolated from P2Y14-knockout mice
Project description:Insulin secretion by pancreatic b-cells is primarily regulated by glucose; however, hormones and additional nutrients, such as long-chain fatty acids, also play an important role in adjusting insulin output to physiologic needs. We examined the role of the short chain fatty acid receptor, GPR41, in funcion of pancreatic beta cells. GPR41 was specifically over-expressed in beta cells by using rat insulin promoter II (41 Tg). Overall design: To further understand GPR41 dependent metabolic phenotype we obsereved in-vivo, we examined mouse islets from 41 Tg and wt littermates. Total RNA was isolated, reverse-transcribed, fragmented, labeled and hybridized to Affymetrix GeneChip Mouse Gene 2.0 ST Array.
Project description:Wolfram syndrome, an autosomal recessive disorder characterized by juvenile-onset diabetes mellitus and optic atrophy, is caused by mutations in the WFS1 gene. WFS1 encodes an endoplasmic reticulum resident transmembrane protein. The Wfs1-null mice exhibit progressive insulin deficiency and diabetes. The aim of the present study was to describe the insulin secretion and transcriptome of pancreatic islets in WFS1-deficient mice. WFS1-deficient (Wfs1KO) mice had considerably less pancreatic islets than heterozygous (Wfs1HZ) or wild-type (WT) mice. Wfs1KO pancreatic islets secreted less insulin after stimulation with 2 and 10 mM glucose and with tolbutamide solution compared to WT and Wfs1HZ islets, but not after stimulation with 20 mM glucose. Differences in proinsulin amount were not statistically significant although there was a trend that Wfs1KO had an increased level of proinsulin. After stimulation with 2 mM glucose solution the proinsulin/insulin ratio in Wfs1KO was significantly higher than that of WT and Wfs1HZ. RNA-seq from pancreatic islets found melastatin-related transient receptor potential subfamily member 5 protein gene (Trpm5) to be downregulated in WFS1-deficient mice. Functional annotation of RNA sequencing results showed that WFS1 deficiency influenced significantly the pathways related to tissue morphology, endocrine system development and function, molecular transport network. These findings suggest an interactive role of WFS1 and TRPM5 in insulin secretion. 12 samples: three genotypes, 4 individuals in each genotype