Epigenetic regulation of Dpp6 expression by Dnmt3b and its novel role in the inhibition of RA induced neuronal differentiation of P19 cells

PLoS One. 2013;8(2):e55826. doi: 10.1371/journal.pone.0055826. Epub 2013 Feb 7.

Abstract

DNA methylation is an important mechanism of gene silencing in mammals catalyzed by a group of DNA methyltransferases including Dnmt1, Dnmt3a, and Dnmt3b which are required for the establishment of genomic methylation patterns during development and differentiation. In this report, we studied the role of DNA methyltransferases during retinoic acid induced neuronal differentiation of P19 cells. We observed an increase in the mRNA and protein level of Dnmt3b, whereas the expression of Dnmt1 and Dnmt3a was decreased after RA treatment of P19 cells which indicated that Dnmt3b is more important during neuronal differentiation of P19 cells. Dnmt3b enriched chromatin library from RA treated P19 cells identified dipeptidyl peptidase 6 (Dpp6) gene as a novel target of Dnmt3b. Further, quantitative ChIP analysis showed that the amount of Dnmt3b recruited on Dpp6 promoter was equal in both RA treated as well as untreated p19 cells. Bisulfite genomic sequencing, COBRA, and methylation specific PCR analysis revealed that Dpp6 promoter was heavily methylated in both RA treated and untreated P19 cells. Dnmt3b was responsible for transcriptional silencing of Dpp6 gene as depletion of Dnmt3b resulted in increased mRNA and protein expression of Dpp6. Consequently, the average methylation of Dpp6 gene promoter was reduced to half in Dnmt3b knockdown cells. In the absence of Dnmt3b, Dnmt3a was associated with Dpp6 gene promoter and regulated its expression and methylation in P19 cells. RA induced neuronal differentiation was inhibited upon ectopic expression of Dpp6 in P19 cells. Taken together, the present study described epigenetic silencing of Dpp6 expression by DNA methylation and established that its ectopic expression can act as negative signal during RA induced neuronal differentiation of P19 cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Base Sequence
  • Cell Culture Techniques
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics*
  • Cell Line
  • CpG Islands
  • DNA (Cytosine-5-)-Methyltransferases / genetics*
  • DNA (Cytosine-5-)-Methyltransferases / metabolism
  • DNA Methylation
  • DNA Methyltransferase 3B
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / genetics*
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / metabolism
  • Epistasis, Genetic*
  • Gene Expression Regulation*
  • Mice
  • Molecular Sequence Data
  • Neurons / cytology*
  • Neurons / drug effects
  • Neurons / metabolism*
  • Promoter Regions, Genetic
  • Protein Binding
  • Tretinoin / pharmacology

Substances

  • Tretinoin
  • DNA (Cytosine-5-)-Methyltransferases
  • DPP6 protein, mouse
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases

Grants and funding

This work was supported by the Program for New Century Excellent Talents in University (NCET-07-0173, 111496019), the National Natural Science Foundation of China (30670689, 30871302 and 31171042), and the Scientific Research Foundation from Northeast Normal University (09ZDQD04). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.