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Project description:Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β cell alterations in triggering the activation of self-reactive T cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity, are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFN-α, a cytokine associated with T1D development. We found that IFN-α triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by upregulation of the exoribonuclease, PNPase old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the upregulation of ten-eleven translocation 2 (TET2) enzyme and increased 5-hydroxymethylcytosine levels in human islets and pancreatic β cells. Moreover, we showed that specific IFN-α expression in the β cells of IFNα-INS1CreERT2 transgenic mice led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFN-α regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.
| S-EPMC6483645 | biostudies-literature
Project description:Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β-cell alterations in triggering the activation of self-reactive T-cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFNα, a cytokine associated with T1D development. We found that IFNα triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by up-regulation of the exoribonuclease, PNPase Old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the up-regulation of ten-eleven translocation TET2 enzyme and increased 5-hydoxymethylcytosine levels in human islets and pancreatic β-cells. Moreover, we showed that specific IFNα expression in the β cells of IFNα-INS1CreERT2 transgenic mice, led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFNα regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.
2019-03-15 | GSE124810 | GEO
Project description:Type 1 diabetes (T1D) is caused by autoimmune destruction of pancreatic β cells. Mounting evidence supports a central role for β-cell alterations in triggering the activation of self-reactive T-cells in T1D. However, the early deleterious events that occur in β cells, underpinning islet autoimmunity are not known. We hypothesized that epigenetic modifications induced in β cells by inflammatory mediators play a key role in initiating the autoimmune response. We analyzed DNA methylation (DNAm) patterns and gene expression in human islets exposed to IFNα, a cytokine associated with T1D development. We found that IFNα triggers DNA demethylation and increases expression of genes controlling inflammatory and immune pathways. We then demonstrated that DNA demethylation was caused by up-regulation of the exoribonuclease, PNPase Old-35 (PNPT1), which caused degradation of miR-26a. This in turn promoted the up-regulation of ten-eleven translocation TET2 enzyme and increased 5-hydoxymethylcytosine levels in human islets and pancreatic β-cells. Moreover, we showed that specific IFNα expression in the β cells of IFNα-INS1CreERT2 transgenic mice, led to development of T1D that was preceded by increased islet DNA hydroxymethylation through a PNPT1/TET2-dependent mechanism. Our results suggest a new mechanism through which IFNα regulates DNAm in β cells, leading to changes in expression of genes in inflammatory and immune pathways that can initiate islet autoimmunity in T1D.
2019-03-15 | GSE124809 | GEO
Project description:Epigenetic modulation of β-cells by interferon-α via PNPT11-miR-26a-TET2 triggers autoimmune diabetes
| PRJNA513846 | ENA
Project description:Epigenetic modulation of β-cells by interferon-α via PNPT11-miR-26a-TET2 triggers autoimmune diabetes [methylation array]
| PRJNA513849 | ENA
Project description:Epigenetic modulation of β-cells by interferon-α via PNPT11-miR-26a-TET2 triggers autoimmune diabetes [RNA-seq]
| PRJNA513850 | ENA
Project description:β cells may participate and contribute to their own demise during Type 1 diabetes (T1D). Here we report a role of their expression of Tet2 in regulating immune killing. Tet2 is induced in murine and human β cells with inflammation but its expression is reduced in surviving β cells. Tet2-KO mice that receive WT bone marrow transplants develop insulitis but not diabetes and islet infiltrates do not eliminate β cells even though immune cells from the mice can transfer diabetes to NOD/scid recipients. Tet2-KO recipients are protected from transfer of disease by diabetogenic immune cells.Tet2-KO β cells show reduced expression of IFNγ-induced inflammatory genes that are needed to activate diabetogenic T cells. Here we show that Tet2 regulates pathologic interactions between β cells and immune cells and controls damaging inflammatory pathways. Our data suggests that eliminating TET2 in β cells may reduce activating pathologic immune cells and killing of β cells.
| S-EPMC8379260 | biostudies-literature
Project description:MicroRNAs contribute to the pathogenesis of certain diseases and may serve as biomarkers. We analyzed glomerular microRNA expression in B6.MRLc1, which serve as a mouse model of autoimmune glomerulonephritis. We found that miR-26a was the most abundantly expressed microRNA in the glomerulus of normal C57BL/6 and that its glomerular expression in B6.MRLc1 was significantly lower than that in C57BL/6. In mouse kidneys, podocytes mainly expressed miR-26a, and glomerular miR-26a expression in B6.MRLc1 mice correlated negatively with the urinary albumin levels and podocyte-specific gene expression. Puromycin-induced injury of immortalized mouse podocytes decreased miR-26a expression, perturbed the actin cytoskeleton, and increased the release of exosomes containing miR-26a. Although miR-26a expression increased with differentiation of immortalized mouse podocytes, silencing miR-26a decreased the expression of genes associated with the podocyte differentiation and formation of the cytoskeleton. In particular, the levels of vimentin and actin significantly decreased. In patients with lupus nephritis and IgA nephropathy, glomerular miR-26a levels were significantly lower than those of healthy controls. In B6.MRLc1 and patients with lupus nephritis, miR-26a levels in urinary exosomes were significantly higher compared with those for the respective healthy control. These data indicate that miR-26a regulates podocyte differentiation and cytoskeletal integrity, and its altered levels in glomerulus and urine may serve as a marker of injured podocytes in autoimmune glomerulonephritis.
| S-EPMC4201534 | biostudies-literature
Project description:Context:Autoimmune thyroid diseases (AITDs) arise from complex interactions among genetic, epigenetic, and environmental factors. Thyroglobulin (TG) is a major susceptibility gene for both Graves disease and Hashimoto thyroiditis. Interferon-? (IFN?), a cytokine secreted during viral infections, has emerged as a key trigger of AITD. We have shown that IFN? upregulates TG transcription; however, how the upregulation of TG transcription by IFN? triggers AITD is still unknown. Objective:To evaluate how IFN? triggers AITD by testing its effects on TG processing. Design:We exposed human thyroid cells to IFN? and evaluated its effects on TG expression and processing. Results:Human thyroid cells exposed to INF? had increased levels of TG mRNA but reduced TG protein levels, indicating TG protein degradation. IFN? induced endoplasmic reticulum stress, but surprisingly, neither the use of chemical chaperones nor proteasome inhibitor prevented IFN?-induced TG degradation. IFN? also increased LysoTracker staining and autophagy flux measured by net light chain 3 (LC3)-II and p62 fluxes. In addition, expression of autophagy markers LC3 and autophagy-related gene 5 was higher in thyroid tissues from patients with AITD. Finally, blocking lysosomal degradation prevented IFN?-induced degradation of TG. Conclusion:We have shown in this study IFN?-induced lysosomal-dependent degradation of TG in human thyroid cells. Our findings suggest that during viral infections, local thyroidal IFN? production can lead to lysosomal TG degradation, releasing pathogenic TG peptides that can trigger AITD.
| S-EPMC6179164 | biostudies-literature
Project description:Successful strategies for treating type 1 diabetes need to restore the function of pancreatic beta cells that are destroyed by the immune system and overcome further destruction of insulin-producing cells. Here, we infused adeno-associated virus carrying Pdx1 and MafA expression cassettes through the pancreatic duct to reprogram alpha cells into functional beta cells and normalized blood glucose in both beta cell-toxin-induced diabetic mice and in autoimmune non-obese diabetic (NOD) mice. The euglycemia in toxin-induced diabetic mice and new insulin+ cells persisted in the autoimmune NOD mice for 4 months prior to reestablishment of autoimmune diabetes. This gene therapy strategy also induced alpha to beta cell conversion in toxin-treated human islets, which restored blood glucose levels in NOD/SCID mice upon transplantation. Hence, this strategy could represent a new therapeutic approach, perhaps complemented by immunosuppression, to bolster endogenous insulin production. Our study thus provides a potential basis for further investigation in human type 1 diabetes.
| S-EPMC5757249 | biostudies-literature