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Project description:Examine expression changes in mouse pancreatic islets following 4 week western diet
2026-03-01 | GSE262313 | GEO
Project description:Pancreatic islet transplantation as a cure for type 1 diabetes (T1D) cannot be scaled up due to a scarcity of human pancreas donors. In vitro expansion of beta cells from mature human pancreatic islets provides an alternative source of insulin-producing cells. The exact nature of the expanded cells produced by diverse expansion protocols, and their potential for differentiation into functional beta cells, remain elusive. We performed a large-scale meta-analysis of gene expression in human pancreatic islet cells, which were processed using three different previously described protocols for expansion and attempted re-differentiation. All three expansion protocols induced dramatic changes in the expression profiles of pancreatic islets; many of these changes are shared among the three protocols. Attempts at re-differentiation of expanded cells induce a limited number of gene expression changes. Nevertheless, these fail to restore a pancreatic islet-like gene expression pattern. Comparison with a collection of public microarray datasets confirmed that expanded cells are highly comparable to mesenchymal stem cells. Genes induced in expanded cells are also enriched for targets of transcription factors important for pluripotency induction. The present data increases our understanding of the active pathways in expanded and re-differentiated islets. Knowledge of the mesenchymal stem cell potential may help development of drug therapeutics to restore beta cell mass in T1D patients. Experiment Overall Design: In this study, we have tested three different protocols to expand human pancreatic islets in monolayer and after attempted maneuvers to re-differentiate the expanded cells back to islets. We have characterized the resulting cells in detail by performing microarray analyses with fresh pancreatic islets, expanded islet cells and re-differentiated cells. Genes modified by either of three protocols have 70 to 80% overlap with the genes changed by the other two protocols. Although there are promising changes in the right direction, none of the three protocols could achieve a return to a functional islet state. The expanded cells highly resemble Mesenchymal Stem Cells (MSC), and similar gene regulatory networks seem to be active in both cell types. On the other hand, the expanded islet cells are different from MSC in that they seem to retain activity of some islet gene modules. The current results highlight the importance of designing new strategies that take into account the MSC potential of expanded cells.
2009-08-07 | E-GEOD-15543 | biostudies-arrayexpress
Project description:Transcriptional and posttranscriptional regulatory networks play a crucial role in the maintenance and adaptation of pancreatic beta-cell function. In this study we show that the levels of the prototypic neuroendocrine miRNA-7 are regulated in islets of obese, diabetic and aged mouse models. Using gain- and loss-of-function models we demonstrate that miR-7 regulates crucial members of the endocrine pancreatic transcriptional network controlling differentiation and insulin synthesis. Importantly, it also directly regulates key proteins in the insulin granule secretory machinery. These results reveal an interconnecting miR-7 genomic circuit that influences beta-cell differentiation, insulin synthesis and release and define a role for miR-7 as an endocrine checkpoint to stabilize beta-cell function during metabolic stress. These findings have implications for miR-7 inhibitors as potential therapies for type 2 diabetes and neurodegenerative diseases. Either miR-7a2 or miR-7b were over-expressed in MIN6 cells using an adenoviral vector. The miR-7a infection was performed in duplicates. In addition, a GFP over-expression in MIN6 using the same viral vector served as control. We also explored the consequence of miR-7a2 deletion in pancreatic beta-cells by generating a beta-cells specific miR-7a2 knock-out using the Lox/Cre system in a C57BL/6 background. We profiled gene expression in mutant and wild-type (control) islets.
2015-06-30 | E-GEOD-48195 | biostudies-arrayexpress
Project description:The progression towards type 2 diabetes depends on the success of the allostatic response of the pancreatic beta cells to synthesise and secrete enough insulin to compensate for insulin resistance. The endocrine pancreas is a plastic tissue able to expand or regress in response to the requirements imposed by physio and pathological states such as pregnancy, obesity or ageing. The mechanisms, mediating beta cell mass expansion in these scenarios are not well defined. We have recently showed that beta cell mass failed to expand in ob/ob mice with genetic ablation of PPARγ2, a mouse model known as the POKO mouse. This phenotype contrasted with the appropriate expansion of the beta cell mass observed in their obese littermate ob/ob mice. Here we investigate PPAR gamma dependent transcriptional responses occurring during early stages of the adaptation of beta cells to insulin resistance. As it could be expected we have identified genes known to regulate proliferation and survival signals of the beta cells. Moreover we have also identified new pathways induced in ob/ob islets that fail to do so in POKO islets. Our data suggest that the expansion of beta cell mass observed in ob/ob islets is associated with activation of immune response and is missing in POKO islets. Other PPARγ dependent differentially regulated pathways include cholesterol biosynthesis, apoptosis through TGF-β signaling and decreased oxidative phosphorylation. In this study, we used gene expression arrays to investigate differences between four experimental classes by pairs
2012-01-16 | E-GEOD-33647 | biostudies-arrayexpress
Project description:Whole proteomic analysis was conducted on isolated mouse pancreatic islets from both WT and C3ar1 KO mice.
2025-05-07 | PXD062327 | Pride
Project description:Insulin-secreting β cells and glucagon-secreting α cells maintain physiological blood glucose levels, and their malfunction drives diabetes development. Using ChIP sequencing and RNA sequencing analysis, we determined the epigenetic and transcriptional landscape of human pancreatic α, β, and exocrine cells. We found that, compared with exocrine and β cells, differentiated α cells exhibited many more genes bivalently marked by the activating H3K4me3 and repressing H3K27me3 histone modifications. This was particularly true for β cell signature genes involved in transcriptional regulation. Remarkably, thousands of these genes were in a monovalent state in β cells, carrying only the activating or repressing mark. Our epigenomic findings suggested that α to β cell reprogramming could be promoted by manipulating the histone methylation signature of human pancreatic islets. Indeed, we show that treatment of cultured pancreatic islets with a histone methyltransferase inhibitor leads to colocalization of both glucagon and insulin and glucagon and insulin promoter factor 1 (PDX1) in human islets and colocalization of both glucagon and insulin in mouse islets. Thus, mammalian pancreatic islet cells display cell-type–specific epigenomic plasticity, suggesting that epigenomic manipulation could provide a path to cell reprogramming and novel cell replacement-based therapies for diabetes. Pancreatic islets were collected post-mortem from 6 human donors and subjected to FACS to separate populations of alpha, beta, and exocrine cells. Depending on the availability of resulting material, sorted islet cell populations were used for H3K4me3, H3K27me3 ChIP-seq, or RNA-seq analysis. All ChIP-seq samples have a corresponding input from the same sample.
2013-08-28 | E-GEOD-50386 | biostudies-arrayexpress
Project description:Impaired proinsulin processing is observed in both type 1 and type 2 diabetes. We have previously shown that reductions in endoplasmic reticulum (ER) calcium (Ca2+) in the pancreatic β cell arising from impaired activity of the Sarcoendoplasmic Reticulum Ca2+ ATPase (SERCA) pump are associated with increased proinsulin secretion. However, the mechanisms responsible for reduced proinsulin processing in the context of SERCA2 deficiency remain incompletely understood. To test this, we developed mice with β cell specific SERCA2 deletion (βS2KO mice) and S2KO INS1 cells. βS2KO mice exhibited age-dependent glucose intolerance and reduced glucose-stimulated insulin secretion without evidence of impaired insulin sensitivity. ER Ca2+ levels in islets from βS2KO mice were significantly reduced, while serum proinsulin/insulin (PI/I) ratios and whole pancreas PI/I content were elevated. Immunoblot analysis of βS2KO islets and S2KO INS-1 cells revealed reduced active forms of the proinsulin processing enzymes, PC1/3, PC2 and CPE. Restoration of SERCA2b via adenoviral transduction in S2KO INS1 cells was sufficient to restore PC1/3 and PC2 maturation and enzyme activity. Brefeldin A treatment in INS1 cells recapitulated the impairments in PC1/3 and PC2 maturation observed in S2KO cells, suggesting a disturbance in protein trafficking between the ER and Golgi. Consistent with this, trafficking assays were performed using a vesicular stomatitis virus G (VSVG) protein construct and revealed a significantly slower rate of VSVG movement from the ER to the Golgi in S2KO INS1 cells. Moreover, pancreas sections from βS2KO mice showed increased co-localization of proinsulin and ProPC2 in the early compartments of the secretory pathway. Taken together, these data suggest that loss of SERCA2 activity and ER Ca2+ loss in the pancreatic β cell leads to impaired proinsulin processing via reduced maturation and trafficking of proinsulin processing enzymes.
2023-10-11 | GSE207498 | GEO
Project description:Gene expression profiles from ALDH high cells sorted from expanded adult human pancreatic organoids are more similar to fetal pancreatic tissue and ALDH high cells sorted from expanded fetal human pancreatic organoids than to adult human islets or adult islet-depleted exocrine tissue.
2019-01-08 | GSE108854 | GEO
Project description:There is mounting evidence indicating that piRNAs are also present in somatic cells where they may accomplish additional regulatory tasks. The aim of this study was to identify the piRNAs expressed in pancreatic islets and to determine whether they are involved in the control of beta-cell activities. piRNA profiling of rat pancreatic islets was performed by microarray. We detected about 18’000 piRNAs in rat pancreatic islets, many of which were differentially expressed throughout islet postnatal development.
2017-06-29 | GSE93790 | GEO
Project description:Recent advances in the understanding of the genetics of type 2 diabetes (T2D) susceptibility have focused attention on the regulation of transcriptional activity within the pancreatic beta-cell. MicroRNAs (miRNAs) represent an important component of regulatory control, and have proven roles in the development of human disease and control of glucose homeostasis. We set out to establish the miRNA profile of human pancreatic islets and of enriched beta-cell populations, and to explore their potential involvement in T2D susceptibility. We used Illumina small RNA sequencing to profile the miRNA fraction in three preparations each of primary human islets and of enriched beta-cells generated by fluorescence-activated cell sorting. In total, 366 miRNAs were found to be expressed (i.e. >100 cumulative reads) in islets and 346 in beta-cells; of the total of 384 unique miRNAs, 328 were shared. A comparison of the islet-cell miRNA profile with those of 15 other human tissues identified 40 miRNAs predominantly expressed (i.e. >50% of all reads seen across the tissues) in islets. Several highly-expressed islet miRNAs, such as miR-375, have established roles in the regulation of islet function, but others (e.g. miR-27b-3p, miR-192-5p) have not previously been described in the context of islet biology. As a first step towards exploring the role of islet-expressed miRNAs and their predicted mRNA targets in T2D pathogenesis, we looked at published T2D association signals across these sites. We found evidence that predicted mRNA targets of islet-expressed miRNAs were globally enriched for signals of T2D association (p-values <0.01, q-values <0.1). At six loci with genome-wide evidence for T2D association (AP3S2, KCNK16, NOTCH2, SCL30A8, VPS26A, and WFS1) predicted mRNA target sites for islet-expressed miRNAs overlapped potentially causal variants. In conclusion, we have described the miRNA profile of human islets and beta-cells and provide evidence linking islet miRNAs to T2D pathogenesis. Examination of the miRNA profiles in 3 preparations of isolated pancreatic islets and 3 preparations of FACS-enriched pancreatic beta-cells
2013-06-07 | E-GEOD-47720 | biostudies-arrayexpress