The Dysregulation of the DLK1- MEG3 Locus in Islets From Patients With Type 2 Diabetes Is Mimicked by Targeted Epimutation of Its Promoter With TALE-DNMT Constructs

Diabetes. 2018 Sep;67(9):1807-1815. doi: 10.2337/db17-0682. Epub 2018 Jul 3.

Abstract

Type 2 diabetes mellitus (T2DM) is characterized by the inability of the insulin-producing β-cells to overcome insulin resistance. We previously identified an imprinted region on chromosome 14, the DLK1-MEG3 locus, as being downregulated in islets from humans with T2DM. In this study, using targeted epigenetic modifiers, we prove that increased methylation at the promoter of Meg3 in mouse βTC6 β-cells results in decreased transcription of the maternal transcripts associated with this locus. As a result, the sensitivity of β-cells to cytokine-mediated oxidative stress was increased. Additionally, we demonstrate that an evolutionarily conserved intronic region at the MEG3 locus can function as an enhancer in βTC6 β-cells. Using circular chromosome conformation capture followed by high-throughput sequencing, we demonstrate that the promoter of MEG3 physically interacts with this novel enhancer and other putative regulatory elements in this imprinted region in human islets. Remarkably, this enhancer is bound in an allele-specific manner by the transcription factors FOXA2, PDX1, and NKX2.2. Overall, these data suggest that the intronic MEG3 enhancer plays an important role in the regulation of allele-specific expression at the imprinted DLK1-MEG3 locus in human β-cells, which in turn impacts the sensitivity of β-cells to cytokine-mediated oxidative stress.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium-Binding Proteins
  • Cell Line
  • Cytokines / metabolism
  • DNA (Cytosine-5-)-Methyltransferase 1 / chemistry
  • DNA (Cytosine-5-)-Methyltransferase 1 / genetics
  • DNA (Cytosine-5-)-Methyltransferase 1 / metabolism
  • DNA Methylation*
  • Diabetes Mellitus, Type 2 / metabolism*
  • Diabetes Mellitus, Type 2 / pathology
  • Enhancer Elements, Genetic
  • Epigenesis, Genetic
  • Gene Expression Regulation*
  • Genetic Loci
  • Green Fluorescent Proteins / chemistry
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Homeobox Protein Nkx-2.2
  • Homeodomain Proteins / chemistry
  • Homeodomain Proteins / genetics
  • Homeodomain Proteins / metabolism
  • Humans
  • Intercellular Signaling Peptides and Proteins / genetics
  • Intercellular Signaling Peptides and Proteins / metabolism*
  • Islets of Langerhans / metabolism*
  • Islets of Langerhans / pathology
  • Locus Control Region
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Mice
  • Mutation
  • Nuclear Proteins
  • Oxidative Stress / drug effects
  • Promoter Regions, Genetic*
  • RNA, Long Noncoding / metabolism*
  • Recombinant Fusion Proteins / chemistry
  • Recombinant Fusion Proteins / metabolism
  • Repressor Proteins / chemistry
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism
  • Tissue Banks
  • Transcription Factors / genetics
  • Transcription Factors / metabolism

Substances

  • Calcium-Binding Proteins
  • Cytokines
  • DLK1 protein, human
  • Homeobox Protein Nkx-2.2
  • Homeodomain Proteins
  • Intercellular Signaling Peptides and Proteins
  • MEG3 non-coding RNA, human
  • Membrane Proteins
  • NKX2-2 protein, human
  • Nkx2-2 protein, mouse
  • Nuclear Proteins
  • RNA, Long Noncoding
  • Recombinant Fusion Proteins
  • Repressor Proteins
  • Tgif1 protein, mouse
  • Transcription Factors
  • Green Fluorescent Proteins
  • DNA (Cytosine-5-)-Methyltransferase 1