title: Methylation of insulin DNA in response to proinflammatory cytokines during the progression of autoimmune diabetes in NOD mice.
abstract: OBJECTIVE
  Type 1 diabetes is caused by the immunological destruction of pancreatic beta cells. Preclinical and clinical data indicate that there are changes in beta cell function at different stages of the disease, but the fate of beta cells has not been closely studied. We studied how immune factors affect the function and epigenetics of beta cells during disease progression and identified possible triggers of these changes.
  
  
  METHODS
  We studied FACS sorted beta cells and infiltrating lymphocytes from NOD mouse and human islets. Gene expression was measured by quantitative real-time RT-PCR (qRT-PCR) and methylation of the insulin genes was investigated by high-throughput and Sanger sequencing. To understand the role of DNA methyltransferases, Dnmt3a was knocked down with small interfering RNA (siRNA). The effects of cytokines on methylation and expression of the insulin gene were studied in humans and mice.
  
  
  RESULTS
  During disease progression in NOD mice, there was an inverse relationship between the proportion of infiltrating lymphocytes and the beta cell mass. In beta cells, methylation marks in the Ins1 and Ins2 genes changed over time. Insulin gene expression appears to be most closely regulated by the methylation of Ins1 exon 2 and Ins2 exon 1. Cytokine transcription increased with age in NOD mice, and these cytokines could induce methylation marks in the insulin DNA by inducing methyltransferases. Similar changes were induced by cytokines in human beta cells in vitro.
  
  
  CONCLUSIONS
  Epigenetic modification of DNA by methylation in response to immunological stressors may be a mechanism that affects insulin gene expression during the progression of type 1 diabetes.
authors.affiliation: Department of Immunobiology, Yale University, 300 George St, New Haven, CT, 06520, USA.
authors.forename: Jinxiu
authors.initials: J
authors.lastname: Rui
authors.affiliation: Department of Immunobiology, Yale University, 300 George St, New Haven, CT, 06520, USA.
authors.forename: Songyan
authors.initials: S
authors.lastname: Deng
authors.affiliation: Department of Immunobiology, Yale University, 300 George St, New Haven, CT, 06520, USA.
authors.forename: Jasmin
authors.initials: J
authors.lastname: Lebastchi
authors.affiliation: Department of Immunobiology, Yale University, 300 George St, New Haven, CT, 06520, USA.
authors.forename: Pamela L
authors.initials: PL
authors.lastname: Clark
authors.affiliation: L2 Diagnostics, New Haven, CT, USA.
authors.forename: Sahar
authors.initials: S
authors.lastname: Usmani-Brown
authors.affiliation: Department of Immunobiology, Yale University, 300 George St, New Haven, CT, 06520, USA. kevan.herold@yale.edu.|Department Internal Medicine, Yale University, New Haven, CT, USA. kevan.herold@yale.edu.
authors.forename: Kevan C
authors.initials: KC
authors.lastname: Herold
mesh_terms: D000328:Adult; D000818:Animals; D016207:Cytokines; D004247:DNA / Q000235:genetics*; D019175:DNA Methylation / Q000235:genetics*; D003922:Diabetes Mellitus, Type 1; D005260:Female; D006801:Humans; D007328:Insulin / Q000235:genetics*; D050417:Insulin-Secreting Cells / Q000378:metabolism*; D051379:Mice; D016688:Mice, Inbred NOD
chemical_list: D016207:Cytokines; D007328:Insulin; D004247:DNA
keywords: Beta cell; Cytokines; DNA methylation; DNA methyltransferases; Dnmt3a; Infiltrating lymphocytes; Ins1; Ins2; Type 1 diabetes