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miR-29 represses the activities of DNA methyltransferases and DNA demethylases

Sumiyo Morita1, Takuro Horii, Mika Kimura

  • 1Laboratory of Genome Science, Biosignal Genome Resource Center, Institute for Molecular and Cellular Regulation, Gunma University, Gunma 371-8512, Japan. msumiyo@gunma-u.ac.jp

International Journal of Molecular Sciences
|July 17, 2013
PubMed

Insights

The microRNA-29 (miR-29) family regulates DNA methylation by inhibiting both DNA methyltransferases and demethylases. This suggests miR-29 suppresses cancer by maintaining existing DNA methylation patterns, not by preventing new ones.

Area of Science:

  • Epigenetics
  • Molecular Biology
  • Cancer Research

Background:

  • MicroRNA-29 (miR-29) family members target DNA methyltransferases (DNMTs), with altered expression linked to cancer.
  • miR-29 is traditionally thought to suppress tumorigenesis by repressing DNA methylation.
  • The precise role of miR-29 in regulating DNA methylation dynamics remains unclear.

Purpose of the Study:

  • To investigate the comprehensive role of miR-29 in regulating DNA methylation.
  • To determine if miR-29 affects DNA methyltransferases and/or DNA demethylases.
  • To elucidate the mechanism by which miR-29 influences DNA methylation status in cancer cells.

Main Methods:

  • Analysis of miR-29 family members' direct targets.
  • Assessment of DNA methyltransferase and demethylase activities.
  • Evaluation of global DNA methylation levels following miR-29 overexpression in cancer cells.

Main Results:

  • miR-29 directly inhibits DNA methyltransferases (DNMT3A, DNMT3B) and key demethylating factors (TET1, TDG).
  • Overexpression of miR-29 led to increased global DNA methylation in some cancer cells.
  • Conversely, miR-29 overexpression resulted in decreased DNA methylation in other cancer cell types.

Conclusions:

  • miR-29 regulates both DNA methylation and demethylation processes.
  • miR-29 appears to suppress tumorigenesis by stabilizing existing DNA methylation patterns.
  • The findings challenge the notion that miR-29 solely prevents de novo DNA methylation.

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