Differential gene expression in beta cells and non-beta cells from islets of NOD mice
Ontology highlight
ABSTRACT: Diabetes (T1D) is a disease in which the immune system destroys the insulin-producing beta cells. Recently, researchers have become interested in the role of the innate immune system in initiating this process. To further investigate this, we used RNA-seq to analyze sorted beta cells from non-diabetic and pre-diabetic female non-obese models of diabetes (NOD). These results shed light on the potential involvement of m6A mediators in the development of T1D, highlighting a promising avenue for future research.
Project description:Beta-cells produce hybrid insulin peptides (HIPs) by linking insulin fragments to other peptides through peptide bonds. HIPs have unique amino acid sequences and are targeted by autoreactive T cells in type 1 diabetes (T1D). Individuals with recent-onset T1D have significantly higher levels of HIP-reactive T cells in their blood compared to non-diabetic control subjects. HIP-reactive T cells have also been found in the residual pancreatic islets of deceased T1D organ donors. In non-obese diabetic (NOD) mice, a major T1D animal model, several CD4 T cell clones that trigger diabetes have been shown to target HIPs. Through mass spectrometry, a subgroup of HIPs containing N-terminal amine groups of various peptides linked to aspartic acid residues of insulin C-peptide has been detected in NOD islets. Our research reveals that these HIPs form spontaneously in beta-cells via an aspartic anhydride intermediate mechanism. This process leads to the creation of a regular HIP with a standard peptide bond and a HIP-isomer (isoHIP) with an isopeptide bond linked to the carboxylic acid side-chain of the aspartic acid residue. Our mass spectrometric analyses confirmed the presence of both HIP isomers in murine islets, thereby validating the occurrence of this new reaction mechanism in beta-cells. The spontaneous formation of neoepitopes through the development of new peptide bonds within cells may contribute to the pathogenesis of T1D and other autoimmune diseases.
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:We recently reported the scalable in vitro production of functional stem cell-derived β cells. Here we extend this approach to generate SC-β cells from Type 1 diabetic patients (T1D), a cell type that is destroyed during disease progression and has not been possible to extensively study. These cells express β cell markers, respond to glucose both in vitro and in vivo, prevent alloxan-induced diabetes in mice, and respond to anti-diabetic drugs. Furthermore, we use an in vitro disease model to demonstrate the cells respond to different forms of β cell stress. Using these assays, we find no major differences in T1D SC-β cells compared to SC-β cells derived from non-diabetic patients (ND). These results show that T1D SC-β cells can be used for the treatment of diabetes, drug screening, and the study of β cell biology.
Project description:Type 1 diabetes (T1D) results from autoimmune destruction of β cells in the pancreas. Protein tyrosine phosphatases (PTPs) are candidate genes for T1D and play a key role in autoimmune disease development and β-cell function. Here, we assessed the global protein and individual PTP profile in the pancreas of diabetic NOD mice treated with anti-CD3 mAb and IL-1RA combination therapy. The treatment reversed hyperglycemia compared to the anti-CD3 alone control group. We observed enhanced expression of PTPN2, a T1D candidate gene, and endoplasmic reticulum (ER) chaperones in the islets from cured mice.
Project description:Non-obese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes as early as 1 month of age, which destruct insulin-producing beta-cells to finally emerge autoimmune diabetes mellitus (T1D) within 8 months. In view, we hypothesized that during the development of T1D, transcriptional modulation of immune reactivity genes may occur as thymocytes mature toward peripheral T lymphocytes. Transcriptome of thymocytes and peripheral CD3+ T lymphocytes from pre-diabetic or diabetic mice analyzed through microarray hybridizations allowed observation of 3,586 differentially expressed genes. Hierarchical clustering grouped mice according to age/T1D onset and genes to their ontology. Transcriptional activity of thymocytes toward peripheral T lymphocytes unraveled sequential participation of genes involved with CD4+/CD8+ T cell differentiation (Themis), tolerance induction (Foxp3), apoptosis (Fasl) to soon after T cell activation (IL4), while the emergence of T1D coincided with the expression of cytotoxicity (Crtam) and inflammatory response genes (Tlr) by peripheral T lymphocytes.
Project description:As early as one month of age, non-obese diabetic (NOD) mice feature pancreatic infiltration of autoreactive T lymphocytes, which destruct insulin-producing beta cells, leading to autoimmune diabetes mellitus (T1D) within eight months. Thus, we hypothesized that during the development of T1D, the transcriptional modulation of immune reactivity genes, as well as, modulation of microRNAs (miRNAs) may occur during thymocytes mature into peripheral CD3+ T lymphocytes. Our aim is to analyze the transcriptional modulation of mRNA and microRNAs during development of thymocytes into peripheral CD3+ T lymphocytes in the context of the emergence of T1D.
Project description:Background: Activation of stress pathways intrinsic to the β cell are thought to both accelerate β cell death and increase β cell immunogenicity in type 1 diabetes (T1D). However, information on the timing and scope of these responses is lacking. Methods: To identify temporal and disease-related changes in islet β cell protein expression, SWATH-MS/MS proteomics analysis was performed on islets collected longitudinally from NOD mice and NOD-SCID mice rendered diabetic through T cell adoptive transfer. Findings: In islets collected from female NOD mice at 10, 12, and 14 weeks of age, we found a time-restricted upregulation of proteins involved in the maintenance of β cell function and stress mitigation, followed by loss of expression of protective proteins that heralded diabetes onset. Pathway analysis identified EIF2 signaling and the unfolded protein response, mTOR signaling, mitochondrial function, and oxidative phosphorylation as commonly modulated pathways in both diabetic NOD mice and NOD-SCID mice rendered acutely diabetic by adoptive transfer, highlighting this core set of pathways in T1D pathogenesis. In immunofluorescence validation studies, β cell expression of protein disulfide isomerase A1 (PDIA1) and 14-3-3b were found to be increased during disease progression in NOD islets, while PDIA1 plasma levels were increased in pre-diabetic NOD mice and in the serum of children with recent-onset T1D compared to age and sex-matched non-diabetic controls. Interpretation: We identified a common and core set of modulated pathways across distinct mouse models of T1D and identified PDIA1 as a potential human biomarker of β cell stress in T1D.
Project description:Type 1 Diabetes (T1D) is characterized by autoimmune-mediated destruction of insulin-producing beta-cells. Recent research has focused on the role of the innate immune system in initiating this process. To investigate this further, we used m6A-profiling of human islets from non-diabetic individuals and the human beta-cell line EndoC-bH1 treated with PBS or interleukin 1 beta and interferon alpha, as well as established T1D patients. Our findings reveal that N6-Methyladenosine (m6A) is a mechanism that helps protect beta-cells by accelerating the decay of mRNA from the 2'-5'-oligoadenylate synthetase (OAS) genes, which controls the antiviral innate immune response at the onset of T1D. These results provide insight into the adaptive safeguarding mechanisms of beta-cells and the role of m6A in T1D development, highlighting potential targets for therapeutic interventions.
Project description:Type 1 diabetes (T1D) is a chronic autoimmune disease that involves immune mediated destruction of β cells. How β cells respond to immune attack is unknown. We identified a population of β cells during the progression of T1D in non-obese diabetic (NOD) mice that survives immune attack. This population develops from normal β cells confronted with islet infiltrates. Pathways involving cell movement, growth and proliferation, immune responses, and cell death and survival are activated in these cells. There is reduced expression of β cell identity genes and diabetes antigens and increased immune inhibitory markers and stemness genes. This new subpopulation is resistant to killing when diabetes is precipitated with cyclosphosphamide. Human β cells show similar changes when cultured with immune cells. These changes may account for the chronicity of the disease and the long term survival of β cells in some patients.
Project description:Transfer RNAs (tRNAs) play a central and well recognized role in protein synthesis. Recent studies revealed that these molecules can be cleaved to generate tRNA fragments (tRFs) with regulatory functions. Here, we studied the contribution of tRFs to pancreatic β-cell loss during the initial phases of type 1 diabetes (T1D), an autoimmune disorder characterized by the invation of immune cells in the pancreas and progressive loss of insulin-secreting cells. Small RNA-profiling showed that the pool of tRFs present in pancreatic β-cells is altered in non-obese diabetic (NOD) mice, a mouse model used to study T1D. We found that part of these changes is triggered by the exposure of β-cells to proinflammatory cytokines released during the autoimmune reaction while others result from the direct transfer of tRFs from autoreactive T lymphocytes to insulin-secreting cells via extracellular vesicles. Indeed, using an RNA-tagging approach, we could demonstrate that a group of tRFs are transferred in vivo in from CD4+CD25- T lymphocytes to pancreatic β-cells, upon T cell adoptive transfer in NOD scid mice. Morevoer, the up-regulation of selected tRFs associated with the autoimmune reaction triggers β-cell apoptosis and gene expression changes that affect the immune regulatory capacity of β-cells. Our data point to tRFs as novel players in type 1 diabetes and potentially in other autoimmune disorders.