Regulation of ER Homeostasis and Cell Cycle by Pax4 Enhances β-Cell Survival and Protects Mice Against Experimental Autoimmune Diabetes
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ABSTRACT:
ORGANISM(S): Mus musculus
PROVIDER: GSE62846 | GEO | 2016/01/01
SECONDARY ACCESSION(S): PRJNA265835
REPOSITORIES: GEO
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Project description:Strategies to enhance islet b-cell survival and regeneration while refraining inflammation through manipulation of molecular targets would provide means to stably replenish the deteriorating functional b-cell mass detected in both Type 1 and Type 2 Diabetes Mellitus (T1DM and T2DM). Herein we report that over expression of the islet enriched transcription factor Pax4 refrains development of hyperglycemia in the RIP-B7.1 mouse model of T1DM through reduced insulitis, decreased b-cell apoptosis correlating with diminished DNA damage and increased proliferation. Transcriptomics revealed up regulation of genes involved in immunomodulation, cell cycle and ER homeostasis in islets over expressing Pax4 as compared to the T2DM-linked mutant variant Pax4R129W. Pax4 but not Pax4R129W protected islets from thapsigargin-mediated ER-stress apoptosis. Collectively, Pax4 is a critical signaling hub coordinating regulation of distinct molecular pathways resulting in improved b-cell fitness whereas Pax4R129W sensitizes to death under stress. More importantly we highlight potential common pharmacological targets for the treatment of DM. 4 groups of 3 samples each. Primary isolated islets of langerhans from either Pax4/rtTA or Pax4R121W/rtTA mice treated or not with Doxicycline.
2016-07-03 | E-GEOD-62846 | biostudies-arrayexpress
Project description:Pancreatic beta-cell dysfunction and death are central in the pathogenesis of type 2 diabetes. Saturated fatty acids cause beta-cell failure and contribute to diabetes development in genetically predisposed individuals. Here we used RNA-sequencing to map transcripts expressed in five palmitate-treated human islet preparations, observing 1,325 modified genes. Palmitate induced fatty acid metabolism and endoplasmic reticulum (ER) stress. Functional studies identified novel mediators of adaptive ER stress signaling. Palmitate modified genes regulating ubiquitin and proteasome function, autophagy and apoptosis. Inhibition of autophagic flux and lysosome function contributed to lipotoxicity. Palmitate inhibited transcription factors controlling beta-cell phenotype including PAX4 and GATA6. 59 type 2 diabetes candidate genes were expressed in human islets, and 11 were modified by palmitate. Palmitate modified expression of 17 splicing factors and shifted alternative splicing of 3,525 transcripts. Ingenuity Pathway Analysis of modified transcripts and genes confirmed that top changed functions related to cell death. DAVID analysis of transcription binding sites in palmitate-modified transcripts revealed a role for PAX4, GATA and the ER stress response regulators XBP1 and ATF6. This human islet transcriptome study identified novel mechanisms of palmitate-induced beta-cell dysfunction and death. The data point to crosstalk between metabolic stress and candidate genes at the beta-cell level. 5 human islet of Langerhans preparations examined under 2 conditions (control and palmitate treatment)
2014-01-09 | E-GEOD-53949 | biostudies-arrayexpress
Project description:Pancreatic beta-cell dysfunction and death are central in the pathogenesis of type 2 diabetes. Saturated fatty acids cause beta-cell failure and contribute to diabetes development in genetically predisposed individuals. Here we used RNA-sequencing to map transcripts expressed in five palmitate-treated human islet preparations, observing 1,325 modified genes. Palmitate induced fatty acid metabolism and endoplasmic reticulum (ER) stress. Functional studies identified novel mediators of adaptive ER stress signaling. Palmitate modified genes regulating ubiquitin and proteasome function, autophagy and apoptosis. Inhibition of autophagic flux and lysosome function contributed to lipotoxicity. Palmitate inhibited transcription factors controlling beta-cell phenotype including PAX4 and GATA6. 59 type 2 diabetes candidate genes were expressed in human islets, and 11 were modified by palmitate. Palmitate modified expression of 17 splicing factors and shifted alternative splicing of 3,525 transcripts. Ingenuity Pathway Analysis of modified transcripts and genes confirmed that top changed functions related to cell death. DAVID analysis of transcription binding sites in palmitate-modified transcripts revealed a role for PAX4, GATA and the ER stress response regulators XBP1 and ATF6. This human islet transcriptome study identified novel mechanisms of palmitate-induced beta-cell dysfunction and death. The data point to crosstalk between metabolic stress and candidate genes at the beta-cell level.
2014-01-09 | GSE53949 | GEO
Project description:The main cause of morbidity and mortality in diabetes mellitus (DM) are cardiovascular complications. Diabetic cardiomyopathy (DCM) remains incompletely understood. Animal models have been crucial in exploring DCM pathophysiology while identifying potential therapeutic targets. Streptozotocin (STZ) has been widely used to produce experimental models of both type 1 and type 2 DM (T1DM and T2DM). Here we compared these two models for their effects on cardiac structure, function, and transcriptome. Different doses of STZ and different diet chows were used to generate T1DM and T2DM in C57BL/6J mice. Normal euglycemic and non-obese sex and age-matched mice served as controls (CTRL). Immunohistochemistry, RT-PCR, and RNA-Seq were employed to compare hearts from the three animal groups. STZ-induced T1DM and T2DM differently affect left ventricular function and myocardial performance. T1DM displays an exaggerated apoptotic cardiomyocyte (CM) death and reactive hypertrophy and fibrosis along with increased cardiac oxidative stress, CM DNA damage and senescence when compared to T2DM mice. T1DM and T2DM differently affect whole cardiac transcriptome. In conclusion, STZ-induced T1DM and T2DM mouse models show significant differences in cardiac remodeling, function and whole transcriptome. These differences could be of key relevance when choosing an animal model to study specific features of DCM.
2023-02-20 | E-MTAB-12558 | biostudies-arrayexpress
Project description:Pancreatic islets are 3-dimensional micro-organs that maintain β-cell functionality via cell-cell and cell-matrix communication. Isolated primary islets are the gold standard for in vitro models. However, native islets present experimental challenges for long-term mechanistic studies owing to their short culture life (approximately 1 week). We developed a novel long-term protocol to study the function of primary islets. The protocol employed reformed islets following dispersion and a fine-tuned culture environment. Reformed islets are highly similar to their primary counterparts across various physiological characteristics. Long-term culture of reformed islets enables high-resolution imaging, repeated functional assessment, and the study of cell-cell communication. Unlike other platforms such as stem cell-derived organoids, reformed islets retain their resident immune populations, making them ideal for studying both resident and infiltrating immune cells and their interactions with hormone-producing islet cells. Qualitative and quantitative analyses revealed that the composition and cytoarchitecture of the reformed islets mimicked those found in primary islets, including the presence of macrophages and CD4+ and CD8+ T cells, which are the key resident immune cell types. Reformed islets secrete insulin and are glucose-responsive, and their β-cells can be stimulated to proliferate using GLP-1 receptor agonism. Furthermore, a comparison of the transcriptomic landscape of isolated human islets and reformed islets generated from the same donor demonstrated a high degree of similarity. Our reformed islets provide an ideal platform to study diabetes pathology. We recapitulated both the T1DM and T2DM disease milieu and validated our model for studying islet immune trafficking and invasion using activated macrophages and T cells. Our data illustrates that reformed islets are an anatomical and functional alternative to native human and mouse islets. Moreover, reformed islets have an advantage over mouse and human β-cell lines, including MIN6 and EndoC-βH1cells, that lack the signalling input of non-β-endocrine cells and immune cell crosstalk. In this study, we showed that reformed islets are a durable paradigm (cell-based model) for islet-based exploration and a means of target discovery/validation for diabetes research.
2023-12-25 | GSE248341 | GEO
Project description:Progressive β–cell failure and apoptosis, resultant of innate immune system activation1,2 is gaining traction as a converging point for type 1 (T1D) and type 2 (T2D). Islet inflammation (insulitis), a hallmark of T1D, occurs typically during the initiation phase of the disease, subsequently orchestrating an autoimmune assault against β–cells. Whether this is a primary event or a consequence of glucotoxicity or lipotoxicity is undetermined3 but metabolic stress is demonstrated to prompt islet inflammation1,2. Here we show that paternal consumption of high fat diet (HFD) invoked distinct immuno-inflammatory transcriptional response in the pancreatic islets of their weanling daughters, in contrast to compensatory changes in the sons. Importantly, these changes occurred in conjunction with transition in islet repertoire resembling the spectrum of T2D, along with progressive development of β–cell dysfunction4. Note, these females were lean, normolipidaemic and insulin sensitive4. These findings provide experimental support for the notion that islet inflammation could be an antecedent event in T2D, leading to β–cell secretory defect, repair/regeneration and apoptosis. Importantly, these effects were transmitted via paternal nutrient stress to offspring.
2021-12-29 | GSE89138 | GEO
Project description:Type 2 diabetes mellitus (T2DM) is a complex disease characterized by the inability of the insulin-producing β-cells in the endocrine pancreas to overcome insulin resistance in peripheral tissues. To determine if microRNAs are involved in the pathogenesis of human T2DM, we sequenced the small RNAs of human islets from diabetic and non-diabetic organ donors. We identified a cluster of miRNAs in an imprinted locus on human chromosome 14q32 that is highly and specifically expressed in human β-cells and dramatically down-regulated in islets from T2DM organ donors. The down-regulation of this locus strongly correlates with hyper-methylation of its promoter. Using HITS-CLIP for the essential RISC-component Argonaute, we identified disease-relevant targets of the chromosome 14q32 microRNAs, such as IAPP and TP53INP1 that cause increased β-cell apoptosis upon over-expression in human islets. Our results support a role for microRNAs and their epigenetic control by DNA methylation in the pathogenesis of T2DM. Identification of miRNA-target interaction in human islets using HITS-CLIP, one mRNA library and one miRNA library
2013-11-22 | E-GEOD-51924 | biostudies-arrayexpress
Project description:Type 2 diabetes mellitus (T2DM) is a multi-factorial disease characterized by the inability of beta-cells in the endocrine pancreas to produce sufficient amounts of insulin to overcome insulin resistance in peripheral tissue. To investigate the function of miRNAs in T2DM, we sequenced the small RNAs of human islets cells from diabetic and non-diabetic organ donors and identified a cluster of miRNAs in an imprinted locus on human chromosome 14 to be dramatically down-regulated in T2DM islets. These miRNAs are highly and specifically expressed in human beta-cells. The down-regulation of this imprinted locus strongly correlates with increased methylation of its promoter in T2DM islets, providing evidence for an epigenetic modification that contributes to the pathogenesis of T2DM. Targets of the Chr 14q32 cluster of miRNAs were identified by high-throughput sequencing of cross-linked and immunoprecipitated RNA (HITS-CLIP) of Argonaute. We have also identified a unique class of sequences, termed chimeric reads, that represent an in vivo ligation of miRNAs and their targets while in complex with Argonaute, and which allow for the direct identification of miRNA:target relationships in vivo. There are three experiments in this submission. All are in human islets or islet cell types. The first is a comparison of miRNA levels in sorted alpha versus beta cells. There is one replicate for this experiment. The second experiment is to measure the expression of miRNAs in whole islets as a function of glucose levels. There are three levels and one replicate for each condition. The third exeriment is a comparison of whole islets taken from human donors that were suspected/confirmed Type 2 diabetic or considered controls. There are 3 controls and 4 T2D samples.
2013-12-01 | E-GEOD-52314 | biostudies-arrayexpress
Project description:Type 1 diabetes (T1D) is an immune-mediated disease that leads to β cell dysfunction and death. However, the contribution of β cells in this process remains unclear. To understand how islet-derived pro-inflammatory signaling pathways contribute to diabetes pathogenesis, we generated inducible islet-specific Alox15 knockout mice on the NOD background. We report that islet-specific deletion of Alox15 induced a substantial increase of β-cell mass and decreased islet insulitis, and ultimately lead to a protection against spontaneous autoimmune diabetes in NOD mice. Single cell RNA-sequencing and mass spectrometry analysis revealed that islet-specific knockout of Alox15 leads to an increase of β cells expressing Pd-l1 and promotes an anti-inflammatory phenotype in myeloid cells and T cells inside the islets. Furthermore, islet- specific Alox15 deletion enhances the expansion of M2-like macrophages and regulatory T cells in the pancreatic islets and pancreatic lymph nodes. Together, these results lead to the conclusion that proinflammatory signals produced by β cells allows these cells to express immunoregulators that protects these cells of immune cell attack and promote β cell survival.
2021-02-11 | GSE166572 | GEO
Project description:Pancreatitis is more frequent in type 2 diabetes (T2DM) although the underlying cause is unknown. We tested the hypothesis that ongoing beta-cell stress and apoptosis in T2DM induces ductal tree proliferation, particularly the pancreatic duct gland (PDG) compartment, and thus potentially obstructs exocrine outflow. PDG replication was increased two-fold in human pancreas from individuals with T2DM (P<0.01), and was associated with increased pancreatic intraepithelial neoplasia (PanINs) (P<0.05), lesions associated with pancreatic inflammation and with the potential to obstruct pancreatic outflow. Increased PDG replication (p<0.05) in the prediabetic HIP rat model of T2DM was concordant with increased beta-cell stress but preceding metabolic derangement. Moreover, the most abundantly expressed chemokines released by the islets in response to beta-cell stress in T2DM, CXCL1, 4 and 10, induced proliferation in human pancreatic ductal epithelium (p<0.05). Also, the diabetes medications that are reported as potential modifiers for the risk of pancreatitis in T2DM modulated PDG proliferation accordingly. We conclude that chronic stimulation and proliferation of the PDG compartment of the pancreas in response to islet inflammation in T2DM is a novel mechanism that serves as a link to the increased risk for pancreatitis in T2DM and may potentially be modified by currently available diabetes therapy.
2016-12-02 | GSE90779 | GEO