Pancreatic islets communicate with lymphoid tissues via exocytosis of insulin peptides
Ontology highlight
ABSTRACT:
OTHER RELATED OMICS DATASETS IN: PXD009919
ORGANISM(S): Mus musculus
PROVIDER: GSE114824 | GEO | 2018/07/18
REPOSITORIES: GEO
Similar Datasets
Project description:Tissue-specific autoimmunity occurs when selected antigens presented by susceptible alleles of the major histocompatibility complex are recognized by T cells. However, the reason why certain specific self-antigens dominate the response and are indispensable for triggering autoreactivity is unclear. Spontaneous presentation of insulin is essential for initiating autoimmune type 1 diabetes in non-obese diabetic mice1,2. A major set of pathogenic CD4 T cells specifically recognizes the 12-20 segment of the insulin B-chain (B:12-20), an epitope that is generated from direct presentation of insulin peptides by antigen-presenting cells3,4. These T cells do not respond to antigen-presenting cells that have taken up insulin that, after processing, leads to presentation of a different segment representing a one-residue shift, B:13-214. CD4 T cells that recognize B:12-20 escape negative selection in the thymus and cause diabetes, whereas those that recognize B:13-21 have only a minor role in autoimmunity3-5. Although presentation of B:12-20 is evident in the islets3,6, insulin-specific germinal centres can be formed in various lymphoid tissues, suggesting that insulin presentation is widespread7,8. Here we use live imaging to document the distribution of insulin recognition by CD4 T cells throughout various lymph nodes. Furthermore, we identify catabolized insulin peptide fragments containing defined pathogenic epitopes in β-cell granules from mice and humans. Upon glucose challenge, these fragments are released into the circulation and are recognized by CD4 T cells, leading to an activation state that results in transcriptional reprogramming and enhanced diabetogenicity. Therefore, a tissue such as pancreatic islets, by releasing catabolized products, imposes a constant threat to self-tolerance. These findings reveal a self-recognition pathway underlying a primary autoantigen and provide a foundation for assessing antigenic targets that precipitate pathogenic outcomes by systemically sensitizing lymphoid tissues.
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Project description:Pancreatic islets communicate with lymphoid tissues via exocytosis of insulin peptides
| PRJNA472771 | ENA
Project description:TAR DNA-binding protein 43 kDa (TDP-43), encoded by TARDBP, is an RNA-binding protein, the nuclear depletion of which is the histopathological hallmark of amyotrophic lateral sclerosis (ALS), a fatal neurodegenerative disorder affecting both upper and lower motor neurons. Besides motor symptoms, patients with ALS often develop nonneuronal signs including glucose intolerance, but the underlying pathomechanism is still controversial, i.e., whether it is impaired insulin secretion and/or insulin resistance. Here, we showed that ALS subjects reduced early-phase insulin secretion and that the nuclear localization of TDP-43 was lost in the islets of autopsied ALS pancreas. Loss of TDP-43 inhibited exocytosis by downregulating CaV1.2 calcium channels, thereby reducing early-phase insulin secretion in a cultured ? cell line (MIN6) and ? cell-specific Tardbp knockout mice. Overexpression of CaV1.2 restored early-phase insulin secretion in Tardbp knocked-down MIN6 cells. Our findings suggest that TDP-43 regulates cellular exocytosis mediated by L-type voltage-dependent calcium channels and thus plays an important role in the early phase of insulin secretion by pancreatic islets. Thus, nuclear loss of TDP-43 is implicated in not only the selective loss of motor neurons but also in glucose intolerance due to impaired insulin secretion at an early stage of ALS.
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Project description:Aims/hypothesisInsulin secretion is widely studied because it plays a central role in glucose homeostasis and diabetes. Processes from insulin granule fusion in beta cells to in vivo insulin secretion have been elucidated, but data at the cellular level do not fully account for several aspects of the macroscopic secretory pattern. Here we investigated how individual secretory events are coordinated spatially and temporally within intact human islets.MethodsWe used the fluorescent probe neuropeptide Y (NPY)-pHluorin to visualise insulin granule secretion in isolated intact human islets.ResultsWe found that individual beta cells respond to increases in glucose concentration by releasing insulin granules in very discrete bursts with periods consistent with in vivo pulsatile insulin secretion. In successive secretory bursts during prolonged exposure to high glucose levels, secretory events progressively localised to preferential release sites, coinciding with the transition to second phase insulin secretion. Granule secretion was very synchronised in neighbouring beta cells, forming discrete regional clusters of activity.Conclusions/interpretationThese results reveal how individual secretory events are coordinated to produce pulsatile insulin secretion from human islets.
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Project description:Heterotopic ossification (HO) is a non-physiological process of bone formation in which progenitor cells in soft tissues differentiate into chondrogenic cells. In the case of fibrodysplasia ossificans progressiva (FOP), a rare genetic disease characterized by progressive and systemic HO, the Activin A/mutated-ACVR1/mTORC1 cascade induces HO in progenitors, one of which is the fibro/adipogenic progenitors (FAPs) in muscle tissues. The relevant biological processes aberrantly regulated by activated mTORC1 remain unclear, however. RNA sequencing analyses revealed the enrichment of genes involved in oxidative phosphorylation (OXPHOS) during Activin A-induced chondrogenesis of mesenchymal stem cells derived from induced pluripotent stem cells (iPSCs) of FOP patients. Functional analyses showed a metabolic transition from glycolysis to OXPHOS during chondrogenesis, in conjunction with an upregulation of mitochondrial biogenesis. mTORC1 inhibition by rapamycin suppressed OXPHOS, and IACS-010759, an inhibitor of OXPHOS, inhibited cartilage matrix formation in vitro, indicating that OXPHOS is principally involved in mTORC1-induced chondrogenesis. Furthermore, IACS-010759 inhibited the muscle injury-induced enrichment of FAP genes and HO in transgenic mice carrying the mutated human ACVR1. These data indicated that OXPHOS is a critical downstream mediator of mTORC1 signaling in chondrogenesis and therefore is a potential FOP therapeutic target.
2024-02-16 | GSE220725 | GEO
Project description:Heterotopic ossification (HO) is a non-physiological process of bone formation in which progenitor cells in soft tissues differentiate into chondrogenic cells. In the case of fibrodysplasia ossificans progressiva (FOP), a rare genetic disease characterized by progressive and systemic HO, the Activin A/mutated-ACVR1/mTORC1 cascade induces HO in progenitors, one of which is the fibro/adipogenic progenitors (FAPs) in muscle tissues. The relevant biological processes aberrantly regulated by activated mTORC1 remain unclear, however. RNA sequencing analyses revealed the enrichment of genes involved in oxidative phosphorylation (OXPHOS) during Activin A-induced chondrogenesis of mesenchymal stem cells derived from induced pluripotent stem cells (iPSCs) of FOP patients. Functional analyses showed a metabolic transition from glycolysis to OXPHOS during chondrogenesis, in conjunction with an upregulation of mitochondrial biogenesis. mTORC1 inhibition by rapamycin suppressed OXPHOS, and IACS-010759, an inhibitor of OXPHOS, inhibited cartilage matrix formation in vitro, indicating that OXPHOS is principally involved in mTORC1-induced chondrogenesis. Furthermore, IACS-010759 inhibited the muscle injury-induced enrichment of FAP genes and HO in transgenic mice carrying the mutated human ACVR1. These data indicated that OXPHOS is a critical downstream mediator of mTORC1 signaling in chondrogenesis and therefore is a potential FOP therapeutic target.
2024-02-16 | GSE221128 | GEO
Project description:We recently discovered hybrid insulin peptides (HIPs) as a novel class of post-translationally modified peptides in murine-derived beta cell tumors, and we demonstrated that these molecules are autoantigens in type 1 diabetes (T1D). A HIP consists of an insulin fragment linked to another secretory granule peptide via a peptide bond. We verified that autoreactive CD4 T cells in both mouse and human autoimmune diabetes recognize these modified peptides. Here, we use mass spectrometric analyses to confirm the presence of HIPs in both mouse and human pancreatic islets. We also present criteria for the confident identification of these peptides. This work supports the hypothesis that HIPs are autoantigens in human T1D and provides a foundation for future efforts to interrogate this previously unknown component of the beta cell proteome.
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Project description:Circadian clocks operative in pancreatic islets participate in the regulation of insulin secretion in humans and, if compromised, in the development of type 2 diabetes (T2D) in rodents. Here we demonstrate that human islet α- and β-cells that bear attenuated clocks exhibit strongly disrupted insulin and glucagon granule docking and exocytosis. To examine whether compromised clocks play a role in the pathogenesis of T2D in humans, we quantified parameters of molecular clocks operative in human T2D islets at population, single islet, and single islet cell levels. Strikingly, our experiments reveal that islets from T2D patients contain clocks with diminished circadian amplitudes and reduced in vitro synchronization capacity compared to their nondiabetic counterparts. Moreover, our data suggest that islet clocks orchestrate temporal profiles of insulin and glucagon secretion in a physiological context. This regulation was disrupted in T2D subjects, implying a role for the islet cell-autonomous clocks in T2D progression. Finally, Nobiletin, an agonist of the core-clock proteins RORα/γ, boosted both circadian amplitude of T2D islet clocks and insulin secretion by these islets. Our study emphasizes a link between the circadian clockwork and T2D and proposes that clock modulators hold promise as putative therapeutic agents for this frequent disorder.
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Project description:In addition to the genetic framework, there are two other critical requirements for the development of tissue-specific autoimmune disease. First, autoreactive T cells need to escape thymic negative selection. Second, they need to find suitable conditions for autoantigen presentation and activation in the target tissue. We show here that these two conditions are fulfilled in diabetic mice of the nonobese diabetic (NOD) strain. A set of autoreactive CD4(+) T cells specific for an insulin peptide, with the noteworthy feature of not recognizing the insulin protein when processed by antigen-presenting cells (APCs), escaped thymic control, participated in diabetes and caused disease. Moreover, APCs in close contact with beta cells in the islets of Langerhans bore vesicles with the antigenic insulin peptides and activated peptide-specific T cells. Our findings may be relevant for other cases of endocrine autoimmunity.
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Project description:NOD-Idd22 mice are congenic mice of NOD background with a piece of chromosome 8 being substituted with ALR genetic material. These mice are resistant to spontaneous autoimmune diabetes as well as chemically induced in vivo islet beta cell destructions. The goal of this project is to come pare gene expressions in islets between NOD-Idd22 and NOD mice. NOD-Rag1 was used instead of NOD to avoid lymphocyte infiltrtation in isltes.
2022-06-27 | GSE206705 | GEO