Epigenetic regulation of autophagy by the methyltransferase G9a

Mol Cell Biol. 2013 Oct;33(20):3983-93. doi: 10.1128/MCB.00813-13. Epub 2013 Aug 5.

Abstract

Macroautophagy is an evolutionarily conserved cellular process involved in the clearance of proteins and organelles. Although the cytoplasmic machinery that orchestrates autophagy induction during starvation, hypoxia, or receptor stimulation has been widely studied, the key epigenetic events that initiate and maintain the autophagy process remain unknown. Here we show that the methyltransferase G9a coordinates the transcriptional activation of key regulators of autophagosome formation by remodeling the chromatin landscape. Pharmacological inhibition or RNA interference (RNAi)-mediated suppression of G9a induces LC3B expression and lipidation that is dependent on RNA synthesis, protein translation, and the methyltransferase activity of G9a. Under normal conditions, G9a associates with the LC3B, WIPI1, and DOR gene promoters, epigenetically repressing them. However, G9a and G9a-repressive histone marks are removed during starvation and receptor-stimulated activation of naive T cells, two physiological inducers of macroautophagy. Moreover, we show that the c-Jun N-terminal kinase (JNK) pathway is involved in the regulation of autophagy gene expression during naive-T-cell activation. Together, these findings reveal that G9a directly represses genes known to participate in the autophagic process and that inhibition of G9a-mediated epigenetic repression represents an important regulatory mechanism during autophagy.

Publication types

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

MeSH terms

  • Animals
  • Autophagy / genetics*
  • Autophagy-Related Proteins
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism
  • Chromatin / metabolism*
  • Chromatin Assembly and Disassembly
  • Epigenesis, Genetic*
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Glucose / deficiency
  • HeLa Cells
  • Histocompatibility Antigens / genetics*
  • Histocompatibility Antigens / metabolism
  • Histone-Lysine N-Methyltransferase / antagonists & inhibitors
  • Histone-Lysine N-Methyltransferase / genetics*
  • Histone-Lysine N-Methyltransferase / metabolism
  • Humans
  • JNK Mitogen-Activated Protein Kinases / genetics
  • JNK Mitogen-Activated Protein Kinases / metabolism
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism
  • Mice
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism
  • Phagosomes / genetics
  • Phagosomes / metabolism
  • Primary Cell Culture
  • RNA, Small Interfering / genetics
  • RNA, Small Interfering / metabolism
  • Signal Transduction
  • T-Lymphocytes / cytology
  • T-Lymphocytes / metabolism*
  • Transcriptional Activation

Substances

  • Autophagy-Related Proteins
  • Carrier Proteins
  • Chromatin
  • Histocompatibility Antigens
  • MAP1LC3B protein, human
  • Membrane Proteins
  • Microtubule-Associated Proteins
  • RNA, Small Interfering
  • WIPI1 protein, human
  • EHMT2 protein, human
  • Histone-Lysine N-Methyltransferase
  • JNK Mitogen-Activated Protein Kinases
  • Glucose