Human Pancreatic Islets Expressing HNF1A Variant Have Defective β cell Transcriptional Regulatory Networks
ABSTRACT: 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:Many patients with type 1 diabetes (T1D) have residual beta cells producing small amounts of C-peptide long after disease onset, but develop an inadequate glucagon response to hypoglycemia following T1D diagnosis. The features of these residual beta cells and alpha cells persisting in the islet endocrine compartment are largely unknown due to difficulty of comprehensive investigation. By studying the T1D pancreas and isolated islets, we show that remnant beta cells appeared to maintain several aspects of regulated insulin secretion. However, the function of T1D alpha cells was markedly reduced and these cells had alterations in transcription factors constituting and alpha and beta cell identity. In the native pancreas and after placing the T1D islets into a non-autoimmune, normoglycemic in vivo environment, there was no evidence of alpha-to-beta cell conversion. These results suggest a new explanation for the disordered T1D counterregulatory glucagon response to hypoglycemia. Overall design: Total of 8 samples were analyzed, 5 were non-diabetic control donors and 3 were T1D donors. α cells were FACS-sorted and RNA was extracted from each of these samples. RNAseq was performed on all 8 samples
Project description:Activating mutations in the KATP channel cause a rare genetic form of diabetes called neonatal diabetes. These mutations render the channel permanently open results in membrane hyperpolarisation of the pancreatic beta-cell. This prevents calcium influx and impairs insulin secretion. Mice expressing the human neonatal diabetes mutation Kir6.2-V59M specifically in pancreatic beta-cells are diabetic but do not display dyslipidaemia or insulin resistance. In this experiment, gene expression changes were analysed to explore the effect of high blood glucose per se on isolated pancreatic islets
Project description:Progressive decline of pancreatic beta cell function is central to the pathogenesis of type 2 diabetes. Protein phosphorylation regulates glucose-stimulated insulin secretion from beta cells, but how signaling networks are remodeled in diabetic islets in vivo remains unknown. Using high-sensitivity mass spectrometry-based proteomics we quantified 6,500 proteins and 13,000 phosphopeptides in islets of obese diabetic mice and matched controls, revealing drastic remodeling of key kinase hubs and signaling pathways. Integration with a literature-derived signaling network implicated GSK3 kinase in the control of the beta cell-specific transcription factor PDX1. Deep phosphoproteomic analysis of human islets chronically treated with high glucose demonstrated a conserved glucotoxicity-dependent role of GSK3 kinase in regulating insulin secretion. Remarkably, the ability of beta cells to secrete insulin in response to glucose was rescued almost completely by pharmacological inhibition of GSK3. Thus, our resource enables investigation of mechanisms and drug targets in type 2 diabetes.
Project description:The NF-κB pathway is a master regulator of inflammatory processes and is implicated in insulin resistance and pancreatic beta cell dysfunction in the metabolic syndrome. While canonical NF-κB signaling is well studied, there is little information on the divergent non-canonical NF-κB pathway in the context of pancreatic islet dysfunction in diabetes. Here, we demonstrate that pharmacological activation of the non-canonical NF-κB inducing kinase (NIK) disrupts glucose homeostasis in zebrafish in vivo. Further, we identify NIK as a critical negative regulator of beta cell function as pharmacological NIK activation results in impaired glucose-stimulated insulin secretion in mouse and human islets. NIK levels are elevated in pancreatic islets isolated from diet-induced obese (DIO) mice, which exhibit increased processing of non-canonical NF-κB components p100 to p52, and accumulation of RelB. Tumor necrosis factor α (TNFα) and receptor activator of NF-κB ligand (RANKL), two ligands associated with diabetes, induce NIK in islets. Mice with constitutive beta cell intrinsic NIK activation present impaired insulin secretion with DIO. NIK activation triggers the non-canonical NF-κB transcriptional network to induce genes identified in human type 2 diabetes genome-wide association studies linked to beta cell failure. These studies reveal that NIK contributes a central mechanism for beta cell failure in diet-induced obesity. We identify a role for Nuclear Factor inducing κB (NIK) in pancreatic beta cell failure. NIK activation disrupts glucose homeostasis in zebrafish in vivo and impairs glucose-stimulated insulin secretion in mouse and human islets in vitro. NIK activation also perturbs beta cell insulin secretion in a diet-induced obesity mouse model. These studies reveal that NIK contributes a central mechanism for beta cell failure in obesity. To uncover the role of NIK in pancreatic beta cells, we performed a gene expression microarray analysis comparing pancreatic islets with constitutive beta cell intrinsicNIK activation from the 16 week old mice (beta cell specific TRAF2 and TRAF2 knockout mice) to their controls (n=3 per group).
Project description:Type 1 and type 2 diabetes (T1D and T2D) share pathophysiological characteristics, yet mechanistic links have remained elusive. T1D results from autoimmune destruction of pancreatic beta cells, while beta cell failure in T2D is delayed and progressive. Here we find a new genetic component of diabetes susceptibility in T1D non-obese diabetic (NOD) mice, identifying immune-independent beta cell fragility. Genetic variation in Xrcc4 and Glis3 alter the response of NOD beta cells to unfolded protein stress, enhancing the apoptotic and senescent fates. The same transcriptional relationships were observed in human islets, demonstrating the role for beta cell fragility in genetic predisposition to diabetes.
Project description:Islet β-cell dysfunction and aggressive macrophage activity are early features in the pathogenesis of type 1 diabetes (T1D). 12/15-lipoxygenase (12/15-LOX) is induced in β cells and macrophages during T1D and produces pro-inflammatory lipids and lipid peroxides that exacerbate β-cell dysfunction and macrophage activity. Inhibition of 12/15-LOX provides a potential therapeutic approach to prevent glycemic deterioration in T1D. Two inhibitors recently identified by our groups through screening efforts, ML127 and ML351, have been shown to selectively target 12/15-LOX with high potency. Only ML351 exhibited no apparent toxicity across a range of concentrations in mouse islets, and molecular modeling suggested reduced promiscuity of ML351 compared to ML127. In mouse islets, incubation with ML351 improved glucose-stimulated insulin secretion in the presence of pro-inflammatory cytokines and triggered gene expression pathways responsive to oxidative stress and cell death. Consistent with a role for 12/15-LOX in promoting oxidative stress, its chemical inhibition reduced production of reactive oxygen species in both mouse and human islets in vitro. In a streptozotocin-induced model of T1D in mice, ML351 prevented the development of diabetes, with coincident enhancement of nuclear Nrf2 in islet cells, reduced β-cell oxidative stress, and preservation of β-cell mass. In the non-obese diabetic mouse model of T1D, administration of ML351 during the prediabetic phase prevented dysglycemia, reduced β-cell oxidative stress, and increased the proportion of anti-inflammatory macrophages in the insulitis. Our data provide the first evidence to date that small molecules that target 12/15-LOX can prevent progression of β-cell dysfunction and glycemic deterioration in models of T1D. Overall design: RNA-seq of Mouse islets treated with vehicle, Proinflammatory cytokine cocktail, and/or ML351 for 24 hours
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.
Project description:As early as one month of age, nonobese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, producing autoimmune diabetes mellitus (T1D) within eightmonths. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes may occur as thymocytes mature into peripheral T lymphocytes. The transcriptome of thymocytes and peripheral CD3+ T lymphocytes from prediabetic or diabetic mice analyzed through microarray hybridizations identified the differentially expressed genes.
Project description:Type 1 diabetes (T1D) is an autoimmune disease triggered by T cell reactivity to protein antigens produced by the β-cells. Here we present a chronological compendium of transcriptional profiles from islets of Langerhans isolated from non-obese diabetic (NOD) mice ranging from 2 wks up to diabetes and compared to controls. Parallel analysis was made of cellular components of the islets. Myeloid cells populated the islets early during development in all mouse strains. This was followed by a type I interferon signature detectable at 4-6 wks of age only in diabetes susceptible mice. Concurrently, CD4 T cells were found within islets, many in contact with intra-islet antigen presenting cells. Early cellular signs of islet reactivity were detected by six wks. By 8 wks, NOD islets contained all major leukocytes populations and an inflammatory gene signature. This work establishes the natural transcriptional signature of T1D and provides a resource for future research. Overall design: 57 RNA samples isolated from the pancreatic islets of langerhans of experimental mice: 2-18 wk old non-obese diabetic (NOD) and newly diabetic NOD were compared to controls: NOD.RAG-/-, B6.g7 and C57BL/6. There were 3 or 6 biological replicates per condition. All mice were female. All data was normalized using RMA in Arraystar. Data table includes normalized probe intensity for every probe.
Project description:Type 1 Diabetes (T1D) is considered to be a Th1 autoimmune disease characterised by an absolute lack of insulin caused by an autoimmune destruction of the insulin producing pancreatic beta cells. Th1 lymphocytes are responsible for the infiltration of the islets of Langerhans and for the cytokine release that supports cytotoxic (Tc) lymphocytes to mediate destruction of the beta cells. The preclinical disease stage is characterized by the generation of the self-reactive lymphocytes that infiltrate the pancreas and selectively destroy the insulin-producing beta cells present in the islets. Other cellular immune mechanisms regarding immunoregulation and antigen presentation and processing are involved in T1D pathogenesis as well. Our aim was to identify genes involved in the corresponding signalling cascades, especially those which may serve as promising diagnostic tools for the identification of persons in the prediabetic phase of the disease. We addressed the question by analysing gene expression profiles of freshly isolated peripheral blood mononuclear cells in type 1 diabetes patients, their first degree relatives divided according to their autoantibody status, and healthy controls. Overall design: 9 T1D-patients versus 10 first degree relatives versus 10 healthy controls