Similar Datasets
Project description:A distinct brain-β-cell circuit regulates insulin secretion
| PRJNA780516 | ENA
Project description:Although persistent elevations in circulating glucose concentrations promote compensatory increases in pancreatic islet mass, unremitting insulin resistance causes a deterioration in beta cell function that disrupts glucose balance and signals the progression to diabetes 1. Glucagon like Peptide 1 (GLP1) agonists improve glucose tolerance in insulin resistance, although some individuals are unresponsive to treatment. Here we show that increases in GLP1 during feeding promote beta cell function in part through the PKA-mediated activation of CREB and its coactivator CRTC2 2. Mice with a knockout of CRTC2 in beta cells have impaired oral glucose tolerance due to decreases in circulating insulin concentrations. CRTC2 was found to promote beta cell function in part by stimulating the expression of the transcription factor MafA. Chronic hyperglycemia associated with high fat or high carbohydrate diet feeding disrupted cAMP signaling in pancreatic islets. Indeed, prolonged elevations in circulating glucose concentrations interfered with CREB signaling by activating the mTOR pathway and triggering the hypoxia inducible factor (HIF1)-dependent induction of the Protein Kinase A Inhibitor beta (PKIB), a potent inhibitor of PKA catalytic activity 3. As disruption of the PKIB gene restored glucose tolerance and insulin secretion in obesity, our results demonstrate how cross-talk between nutrient and hormonal pathways contributes to loss of pancreatic islet function in insulin resistance. Rat insulinoma cells were used to interrogate the impact of glucose exposure and CREB activity on cAMP dependent gene regulation in the pancreatic beta cells
2015-02-23 | E-GEOD-60158 | biostudies-arrayexpress
Project description:Objective: Histone deacetylases are epigenetic regulators known to control gene transcription in various tissues. A member of this family, histone deacetylase 3 (HDAC3), has been shown to regulate metabolic genes. Cell culture studies with HDAC-specific inhibitors and siRNA suggest that HDAC3 plays a role in pancreatic β-cell function, but a recent genetic study in mice has been contradictory. Here we address the functional role of HDAC3 in β-cells of adult mice. Methods: An HDAC3 β-cell specific knockout was generated in adult MIP-CreERT transgenic mice using the Cre-loxP system. Induction of HDAC3 deletion was initiated at 8 weeks of age with administration of tamoxifen in corn oil (2 mg/day for 5 days). Mice were assayed for glucose tolerance, glucose-stimulated insulin secretion, and islet function 2 weeks after induction of the knockout. Transcriptional functions of HDAC3 were assessed by ChIP-seq as well as RNA-seq comparing control and -cell knockout islets. Results: HDAC3 β-cell specific knockout (HDAC3βKO) did not increase total pancreatic insulin content or β-cell mass. However, HDAC3βKO mice demonstrated markedly improved glucose tolerance. This improved glucose metabolism coincided with increased basal and glucose-stimulated insulin secretion in vivo as well as in isolated islets. Cistromic and transcriptomic analyses of pancreatic islets revealed that HDAC3 regulates multiple genes that contribute to glucose-stimulated insulin secretion. Conclusions: HDAC3 plays an important role in regulating insulin secretion in vivo and therapeutic intervention may improve glucose homeostasis.
2016-11-26 | GSE90531 | GEO
Project description:Dll4-Notch signaling is required for cell fate decisions and neoplasias. However, emerging evidence suggests a role for Dll4-Notch signaling in metabolic and immune diseases. To date, there is no evidence of a direct effect of Dll4-Notch signaling inhibition on pancreatic islet function and insulin secretion.
2018-08-13 | PXD005333 | Pride
Project description:Hyperinsulinemia often precedes type 2 diabetes but its role in disease progression is unknown. Palmitoylation, a protein modification implicated in regulated exocytosis, is reversed by acyl-protein thioesterase 1 (APT1). We found altered APT1 biology in pancreatic islets from humans with type 2 diabetes, and APT1 knockdown in nondiabetic human islets caused insulin hypersecretion. Chow fed global and islet specific APT1 knockout mice had enhanced glucose tolerance due to islet autonomous increased glucose-stimulated insulin secretion. APT1 deficiency did not affect islet calcium dynamics but prolonged insulin granule fusion. Using palmitoylation proteomics, we identified Scamp1 as an APT1 substrate that localized to insulin secretory granules. Knockdown of Scamp1 caused insulin hypersecretion. APT1 deficient insulinoma cells subjected to nutrient excess had increased apoptosis, and expression of a mutated Scamp1 incapable of being palmitoylated in APT1 deficient cells rescued insulin hypersecretion and nutrient induced apoptosis. Compared to APT1 sufficient controls, high fat fed islet specific APT1 knockout mice and global APT1 deficient db/db mice showed increased -cell failure. These findings suggest that the depalmitoylation enzyme APT1 is regulated in human islets, and that APT1 deficiency causes insulin hypersecretion leading to -cell failure, modeling the evolution of some forms of human type 2 diabetes.
2023-11-05 | PXD038554 | Pride
Project description:DEAD-box helicase 1 (DDX1) is a multifunction protein involved in diverse cellular processes including transcription, viral replication, mRNA/miRNA processing, and tRNA splicing. Here, we report a novel function of DDX1 in mRNA alternative splicing in pancreatic β cells. By performing integrated data analysis of high-throughput RNA sequencing (RNA-Seq), and cross-linking and immunoprecipitation coupled with deep sequencing (CLIP-Seq), we identify hundreds of alternative splicing genes that are targeted by DDX1. These DDX1-targeted alternative splicing genes are mainly associated with calcium ion binding, high voltage-gated calcium channel, and transmembrane transporter. Functionally, silencing DDX1 impairs calcium influx and insulin secretion in the pancreatic β cells. These results reveal an important role for DDX1 in the regulation of gene alternative splicing and insulin secretion in pancreatic β cells.
2018-05-02 | GSE113893 | GEO
Project description:Insulin secreted by pancreatic β cells is essential for maintaining the level of blood glucose. Diabetes is mainly caused by the loss of β cells or impaired β cell function. The previous study performed a whole transcriptome analysis on the islets of T2D and the control group, and the results showed that the splicing disorder of the splicing event was about 25%, breast carcinoma amplified sequence 2(BCAS2) is one of the components of the spliceosome, and its function in islet β cell is unclear. Here we report that knockdown of Bcas2 decreases in glucose and KCl-stimulated insulin secretion in the NIT-1 cell line. The pancreas weight, glucose tolerance and insulin sensitivity were detected in normal chow-fed and high-fat diet-fed Bcas2 f/f-βKO mice, and β cell mass and islet size was analyzed by immunohistochemistry. Glucose intolerance developed in Bcas2 f/f-βKO mice, but there were no significant differences in pancreas weight, insulin sensitivity, β cell mass and islet size. Further, GSIS and observation of insulin secretion granules were performed on normal chow-fed mice, and it was found that the insulin level in serum decreased and the number of insulin secretion granules decreased in Bcas2 f/f-βKO mice, which was related to the abnormal splicing of Syt7 and Tcf7l2 pre-mRNA. Taken together, these results demonstrate that BCAS2 is involved in alternative splicing during insulin synthesis and secretion. Elisa,islet isolation,insulin secretion
2024-06-01 | GSE224490 | GEO
Project description:The activity of pancreatic islets’ insulin-producing β-cells is closely regulated by systemic cues and, locally, by adjacent islet hormone-producing “non-β-cells” (namely α-, δ- and γ-cells). Still, it is unclear whether the presence of the non-β-cells is a requirement for accurate insulin secretion. Here, we generated and studied a mouse model in which adult islets are exclusively composed of β-cells, and human pseudoislets containing only primary β-cells. Mice lacking non-β-cells had optimal blood glucose regulation. They exhibited enhanced glucose tolerance, insulin sensitivity and restricted body weight gain under high-fat diet. The insulin secretion dynamics in islets composed of only β-cells was like in intact islets, both in homeostatic conditions and upon extreme insulin demand. Similarly, human β-cell pseudoislets retained the glucose-regulated mitochondrial respiration, insulin secretion and exendin-4 responses of human islets comprising all four cell types. Together, the findings indicate that non-β-cells are dispensable for blood glucose homeostasis and β-cell function. This is particularly relevant in diabetes, where non-β-cells become dysfunctional and worsen the disease’s pathophysiology. These results support efforts aimed at developing diabetes treatments by generating β-like cell clusters devoid of non-β-cells, as for example from human embryonic stem cells and/or by in situ conversion of non-β-cells into insulin producers.
2024-07-19 | GSE226479 | GEO
Project description:Pancreatic beta-cell dysfunction contributes to onset and progression of type 2 diabetes. In this state beta-cells become metabolically inflexible, losing the ability to select between carbohydrates and lipids as substrates for mitochondrial oxidation. These changes lead to beta-cell dedifferentiation. We have proposed that FoxO proteins are activated through deacetylation-dependent nuclear translocation to forestall the progression of these abnormalities. However, how deacetylated FoxO exert their actions remains unclear. To address this question, we analyzed islet function in mice homozygous for knock-in alleles encoding deacetylated FoxO1 (6KR). Islets expressing 6KR mutant FoxO1 have enhanced insulin secretion in vivo and ex vivo, and decreased fatty acid oxidation ex vivo. Remarkably, the gene expression signature associated with FoxO1 deacetylation differs from wild-type by only ~2% of the > 4,000 genes regulated in response to re-feeding. But this narrow swath includes key genes required for beta-cell identity, lipid metabolism, and mitochondrial fatty acid and solute transport. The data support the notion that deacetylated FoxO1 protects beta-cell function by limiting mitochondrial lipid utilization, and raise the possibility that inhibition of fatty acid oxidation in β-cells is beneficial to diabetes treatment.
2016-05-10 | GSE77652 | GEO
Project description:The IL-22RA1 receptor is highly expressed in the pancreas, and exogenous IL-22 has been shown to reduce endoplasmic reticulum and oxidative stress in human pancreatic islets and promote secretion of high-quality insulin from beta-cells. However, the endogenous role of IL-22RA1 signaling on these cells remains unclear. Here, we show that antibody neutralisation of IL-22RA1 in cultured human islets leads to impaired insulin quality and increased cellular stress. Through the generation of mice lacking IL-22ra1 specifically on pancreatic alpha- or beta-cells, we demonstrate that ablation of murine beta-cell IL-22ra1 leads to similar decreases in insulin secretion, quality and islet regeneration, whilst increasing islet cellular stress, inflammation and MHC II expression. These changes in insulin secretion led to impaired glucose tolerance, a finding more pronounced in female animals compared to males. Our findings attribute a regulatory role for endogenous pancreatic beta-cell IL-22ra1 in insulin secretion, islet regeneration, inflammation/cellular stress and appropriate systemic metabolic regulation.
2024-04-16 | GSE262867 | GEO