DNA methyltransferase controls stem cell aging by regulating BMI1 and EZH2 through microRNAs

PLoS One. 2011 May 10;6(5):e19503. doi: 10.1371/journal.pone.0019503.

Abstract

Epigenetic regulation of gene expression is well known mechanism that regulates cellular senescence of cancer cells. Here we show that inhibition of DNA methyltransferases (DNMTs) with 5-azacytidine (5-AzaC) or with specific small interfering RNA (siRNA) against DNMT1 and 3b induced the cellular senescence of human umbilical cord blood-derived multipotent stem cells (hUCB-MSCs) and increased p16(INK4A) and p21(CIP1/WAF1) expression. DNMT inhibition changed histone marks into the active forms and decreased the methylation of CpG islands in the p16(INK4A) and p21(CIP1/WAF1) promoter regions. Enrichment of EZH2, the key factor that methylates histone H3 lysine 9 and 27 residues, was decreased on the p16(INK4A) and p21(CIP1/WAF1) promoter regions. We found that DNMT inhibition decreased expression levels of Polycomb-group (PcG) proteins and increased expression of microRNAs (miRNAs), which target PcG proteins. Decreased CpG island methylation and increased levels of active histone marks at genomic regions encoding miRNAs were observed after 5-AzaC treatment. Taken together, DNMTs have a critical role in regulating the cellular senescence of hUCB-MSCs through controlling not only the DNA methylation status but also active/inactive histone marks at genomic regions of PcG-targeting miRNAs and p16(INK4A) and p21(CIP1/WAF1) promoter regions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Azacitidine / pharmacology
  • Blotting, Western
  • Cell Cycle / drug effects
  • Cell Cycle / genetics
  • Cell Proliferation / drug effects
  • Cells, Cultured
  • Cellular Senescence / drug effects
  • Cellular Senescence / genetics*
  • Chromatin Immunoprecipitation
  • CpG Islands / genetics
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases / antagonists & inhibitors
  • DNA (Cytosine-5-)-Methyltransferases / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism*
  • Enhancer of Zeste Homolog 2 Protein
  • Enzyme Inhibitors / pharmacology
  • Flow Cytometry
  • Humans
  • Immunohistochemistry
  • MicroRNAs / genetics*
  • Multipotent Stem Cells / cytology
  • Multipotent Stem Cells / metabolism
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Polycomb Repressive Complex 1
  • Polycomb Repressive Complex 2
  • Proto-Oncogene Proteins / genetics
  • Proto-Oncogene Proteins / metabolism*
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism*
  • Reverse Transcriptase Polymerase Chain Reaction
  • Transcription Factors / genetics
  • Transcription Factors / metabolism*

Substances

  • BMI1 protein, human
  • DNA-Binding Proteins
  • Enzyme Inhibitors
  • MicroRNAs
  • Nuclear Proteins
  • Proto-Oncogene Proteins
  • Repressor Proteins
  • Transcription Factors
  • DNA (Cytosine-5-)-Methyltransferase 1
  • DNA (Cytosine-5-)-Methyltransferases
  • DNA methyltransferase 3B
  • DNMT1 protein, human
  • EZH2 protein, human
  • Enhancer of Zeste Homolog 2 Protein
  • Polycomb Repressive Complex 2
  • Polycomb Repressive Complex 1
  • Azacitidine