Loss of RREB1 in pancreatic beta cells reduces cellular insulin content and affects endocrine cell gene expression
Ontology highlight
ABSTRACT:
PROVIDER: EGAS00001006314 | EGA |
REPOSITORIES: EGA
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Project description:Genome-wide studies have uncovered multiple independent signals at the
RREB1 locus associated with altered type 2 diabetes (T2D) risk and related glycemic traits.
However, little is known about the function of the zinc finger transcription factor RREB1 in
glucose homeostasis or how changes in its expression and/or function influence diabetes risk.
We studied its function using three transcriptomic strategies, profiling gene expression when RREB1 is knocked out or knocked down in the Endo-betaH1 cell line, in addition to the in vitro differentiation in hiPSCs.
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Project description:Diabetes mellitus is associated with serious long-term complications, including increased cardiovascular risk and a higher occurrence of infections. These diabetes-related complications are suggestive of altered responses of the innate immune system. Recent studies have shown that energy metabolism of monocytes is a crucial determinant of their functionality. Here we investigate whether metabolism and function of monocytes are changed in patients with diabetes and aim to identify diabetes-associated factors driving these alterations. Patients with type 1 diabetes (T1D) and healthy age-, sex- and BMI-matched nondiabetic controls were recruited and detailed characteristics related to disease status including diabetes duration and glycemic burden (HbA1c levels) were collected. Monocytes were isolated from peripheral blood to determine immune functionality, metabolic responses and to perform transcriptome analyses. Upon ex vivo stimulation with TLR-4 agonist LPS or TLR-2 agonist P3C, monocytes of patients with T1D secreted lower levels of various cytokines (TNFα, IL-1β and IL-1Ra) and had lower glycolytic rates in comparison to monocytes isolated from matched controls. Stratification based on HbA1c levels revealed that a lower cytokine secretion was coupled to a higher glycolytic rate of monocytes in patients with a higher glycemic burden. Gene expression signatures of circulating monocytes displayed an enhanced inflammatory expression pattern that was associated with this high glycemic burden. A high glycemic burden in patients with T1D promotes expression of inflammatory genes of monocytes in vivo and is coupled to an impaired relationship between metabolism and inflammatory function upon activation ex vivo.
2020-10-09 | GSE154609 | GEO
Project description:Glycemic control is a strong predictor of long-term cardiovascular risk in patients with diabetes mellitus, and poor glycemic control influences long-term risk of cardiovascular disease even decades after optimal medical management. This phenomenon, termed glycemic memory, has been proposed to occur due to stable programs of cardiac and endothelial cell gene expression. This transcriptional remodeling has been shown to occur in the vascular endothelium through a yet undefined mechanism of cellular reprogramming. Epigenetics offers a novel mechanism whereby a transient glycemic stress is capable of modifying endothelial susceptibility to the pathological remodeling of cardiovascular disease. In the current study, we show that transient glucose exposure triggers widespread alterations in endothelial DNA methylation which may control several recognized pathological mechanisms of cardiovascular disease, such as the nitric oxide signaling cascade. Future mechanistic studies should therefore investigate the extent to which differential methylation potentiates endothelial dysfunction in response to transient glycemic stress.
2020-12-19 | GSE163510 | GEO
Project description:PAX4 loss of function alters human endocrine cell development and influences diabetes risk.
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Project description:The N-terminal three zinc finger motifs of PARP1 are evolutionarily conserved in multicellular organism。However, during apoptosis, human PARP1 is mainly cleaved by caspase 3 at D214. As a result, the truncated PARP1 loses two N-terminal zinc finger motifs and only contains the third zinc finger motif, the BRCT domain, the WGR domain and the C-terminal catalytic domain. Interestingly, when we explored the domain architecture of PARP1 in other organisms, we found that similar to human tPARP1, PARP1 orthologs in several lower organisms do not have the N-terminal two zinc fingers or even they lack the third zinc finger motif. It indicates that even without the first two zinc finger motifs, tPARP1 may still catalyze ADP-ribosylation and play an important role in certain biological processes. To reveal the biological function of tPARP1, we performed tandem affinity purification and searched for the possible substrates.
2022-02-15 | PXD018691 | Pride
Project description:The rare SLC30A8 mutation encoding a truncating p.Arg138* variant (R138X) in zinc transporter 8 (ZnT8) is associated with a 65% reduced risk for type 2 diabetes. To determine whether ZnT8 is required for beta cell development and function, we derived human pluripotent stem cells carrying the R138X mutation and differentiated them into insulin-producing cells. We found that human pluripotent stem cells with homozygous or heterozygous R138X mutation and the null (KO) mutation have normal efficiency of differentiation towards insulin-producing cells, but these cells show diffuse granules that lack crystalline zinc-containing insulin granules. Insulin secretion is not compromised in vitro by KO or R138X mutations in human embryonic stem cell-derived beta cells (sc-beta cells). Likewise, the ability of sc-beta cells to secrete insulin and maintain glucose homeostasis after transplantation into mice was comparable across different genotypes. Interestingly, sc-beta cells with the ZnT8 KO mutation showed increased cytoplasmic zinc, and cells with either KO or R138X mutation were resistant to apoptosis when extracellular zinc was limiting. These findings are consistent with a protective role of zinc in cell death and with the protective role of zinc in T2D.
2022-02-11 | GSE166641 | GEO
Project description:Diabetes is a major chronic disease with an excessive healthcare burden on society. A coding variant (p.Arg192His) in the transcription factor PAX4 is uniquely and reproducibly associated with altered risk for type 2 diabetes (T2D) in East Asian populations, whilst rare PAX4 alleles have been proposed to cause monogenic diabetes8. In mice, Pax4 is essential for beta cell formation but neither the role of diabetes-associated variants in PAX4 nor PAX4 itself on human beta cell development and/or function are known. Here, we demonstrate that non-diabetic carriers of either the PAX4 p.Arg192His or a newly identified p.Tyr186X allele exhibit decreased pancreatic beta cell function. In the human beta cell model, EndoC-βH1, PAX4 knockdown led to impaired insulin secretion, reduced total insulin content and altered hormone gene expression. Deletion of PAX4 in isogenic human induced pluripotent stem cell (hiPSC)-derived beta-like cells resulted in de-repression of alpha cell gene expression whilst in vitro differentiation of hiPSCs from carriers of PAX4 p.192His and p.186X alleles exhibited increased polyhormonal endocrine cell formation and reduced insulin content. In silico and in vitro studies showed that these PAX4 alleles cause either reduced PAX4 expression or function. Correction of the diabetes-associated PAX4 alleles reversed these phenotypic changes. Together, we demonstrate the role of PAX4 in human endocrine cell development, beta cell function and its contribution to type 2 diabetes risk.
2023-08-05 | GSE203264 | GEO
Project description:Diabetes is a major chronic disease with an excessive healthcare burden on society. A coding variant (p.Arg192His) in the transcription factor PAX4 is uniquely and reproducibly associated with altered risk for type 2 diabetes (T2D) in East Asian populations, whilst rare PAX4 alleles have been proposed to cause monogenic diabetes8. In mice, Pax4 is essential for beta cell formation but neither the role of diabetes-associated variants in PAX4 nor PAX4 itself on human beta cell development and/or function are known. Here, we demonstrate that non-diabetic carriers of either the PAX4 p.Arg192His or a newly identified p.Tyr186X allele exhibit decreased pancreatic beta cell function. In the human beta cell model, EndoC-βH1, PAX4 knockdown led to impaired insulin secretion, reduced total insulin content and altered hormone gene expression. Deletion of PAX4 in isogenic human induced pluripotent stem cell (hiPSC)-derived beta-like cells resulted in de-repression of alpha cell gene expression whilst in vitro differentiation of hiPSCs from carriers of PAX4 p.192His and p.186X alleles exhibited increased polyhormonal endocrine cell formation and reduced insulin content. In silico and in vitro studies showed that these PAX4 alleles cause either reduced PAX4 expression or function. Correction of the diabetes-associated PAX4 alleles reversed these phenotypic changes. Together, we demonstrate the role of PAX4 in human endocrine cell development, beta cell function and its contribution to type 2 diabetes risk.
2023-08-05 | GSE202206 | GEO
Project description:SLC30A8 encodes a zinc transporter that is primarily expressed in the pancreatic islets of Langerhans. In beta-cells it transports zinc into insulin-containing secretory granules. Loss-of-function (LOF) mutations in SLC30A8 protect against type 2 diabetes in humans. In this study, we generated a mouse model carrying one of the most common human LOF mutations for SLC30A8, R138X. The R138X mice had normal body weight, glucose tolerance and pancreatic beta-cell mass. Interestingly, in hyperglycemic conditions induced by the insulin receptor antagonist S961, the R138X mice showed a 50% increase in insulin secretion. This effect was not associated with enhanced beta-cell proliferation or beta-cell mass. Our data suggest that the SLC30A8 R138X LOF mutation in humans may protect from type 2 diabetes in part by increasing the capacity of beta-cells to secrete insulin.
2018-11-01 | GSE114207 | GEO
Project description:Type 2 diabetes (T2D) is major cause of mortality and morbidity. The key manifestations of this disease are insulin resistance (IR), hyperglycemia and hyperinsulinemia. Secretion of insulin from the endocrine pancreas is triggered by elevated circulating glucose and acts on skeletal muscle and adipose tissues to remove excess glucose from the blood (1). This is achieved through a series of intracellular events that trigger the translocation of vesicles containing the glucose transporter 4 (GLUT4) to the surface of skeletal muscle cells and adipocytes (2,3). This process is impaired in patients with IR or T2D and insulin fails to promote GLUT4 translocation, thus resulting in inefficient glucose uptake in storage tissue and hyperglycemia (4). Chronic hyperglycemic condition increases the risk of cardiovascular disease, stroke, neuropathy, and death (5). Previously developed insulin sensitizer like thiazolidinediones (TZDs) have proven effective in improving glycemic control, however, they significantly increase the risk of cardiovascular disease due to their agonist activity at PPAR(6-8). Consequently, identifying insulin sensitizers that restore insulin-stimulated GLUT4 translocation in diabetic patients without targeting PPAR is urgently needed. The discovery of such molecules has been challenging due to the lack of a GLUT4 translocation assay amenable to high throughput screening (HTS). For this reason, we have developed a new luminescence based HTS assay that allows real time monitoring of GLUT4 translocation in mammalian cells and further adapted the assay to measure GLUT4 translocation in live mice. Using this assay, we identified a new insulin sensitizer which greatly improves insulin-dependent glucose uptake in storage tissues and glucose tolerance in insulin resistant rodents. This new insulin sensitizers acts through interaction with the Unc119 family of proteins which are known to facilitate the transport of specific cargos (9) but had not yet been implicated in insulin action or GLUT4 translocation. This study identifies new PPAR-independent insulin sensitizers with in-vivo efficacy and identify Unc119 proteins as new targets for the treatment of T2D.
2024-07-03 | PXD034052 | Pride