Lysine-specific demethylase 1-mediated demethylation of histone H3 lysine 9 contributes to interleukin 1β-induced microsomal prostaglandin E synthase 1 expression in human osteoarthritic chondrocytes

Arthritis Res Ther. 2014 May 16;16(3):R113. doi: 10.1186/ar4564.

Abstract

Introduction: Microsomal prostaglandin E synthase 1 (mPGES-1) catalyzes the terminal step in the biosynthesis of PGE2, a critical mediator in the pathophysiology of osteoarthritis (OA). Histone methylation plays an important role in epigenetic gene regulation. In this study, we investigated the roles of histone H3 lysine 9 (H3K9) methylation in interleukin 1β (IL-1β)-induced mPGES-1 expression in human chondrocytes.

Methods: Chondrocytes were stimulated with IL-1β, and the expression of mPGES-1 mRNA was evaluated using real-time RT-PCR. H3K9 methylation and the recruitment of the histone demethylase lysine-specific demethylase 1 (LSD1) to the mPGES-1 promoter were evaluated using chromatin immunoprecipitation assays. The role of LSD1 was further evaluated using the pharmacological inhibitors tranylcypromine and pargyline and small interfering RNA (siRNA)-mediated gene silencing. The LSD1 level in cartilage was determined by RT-PCR and immunohistochemistry.

Results: The induction of mPGES-1 expression by IL-1β correlated with decreased levels of mono- and dimethylated H3K9 at the mPGES-1 promoter. These changes were concomitant with the recruitment of the histone demethylase LSD1. Treatment with tranylcypromine and pargyline, which are potent inhibitors of LSD1, prevented IL-1β-induced H3K9 demethylation at the mPGES-1 promoter and expression of mPGES-1. Consistently, LSD1 gene silencing with siRNA prevented IL-1β-induced H3K9 demethylation and mPGES-1 expression, suggesting that LSD1 mediates IL-1β-induced mPGES-1 expression via H3K9 demethylation. We show that the level of LSD1 was elevated in OA compared to normal cartilage.

Conclusion: These results indicate that H3K9 demethylation by LSD1 contributes to IL-1β-induced mPGES-1 expression and suggest that this pathway could be a potential target for pharmacological intervention in the treatment of OA and possibly other arthritic conditions.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Blotting, Western
  • Cells, Cultured
  • Chondrocytes / drug effects*
  • Chondrocytes / metabolism
  • Gene Expression / drug effects
  • Histone Demethylases / antagonists & inhibitors
  • Histone Demethylases / genetics
  • Histone Demethylases / metabolism*
  • Histones / metabolism*
  • Humans
  • Interleukin-1beta / pharmacology*
  • Intramolecular Oxidoreductases / genetics
  • Intramolecular Oxidoreductases / metabolism*
  • Lysine / metabolism*
  • Methylation / drug effects
  • Middle Aged
  • Monoamine Oxidase Inhibitors / pharmacology
  • Osteoarthritis / genetics
  • Osteoarthritis / metabolism
  • Osteoarthritis / pathology
  • Pargyline / pharmacology
  • Promoter Regions, Genetic / genetics
  • Prostaglandin-E Synthases
  • Protein Binding
  • RNA Interference
  • Reverse Transcriptase Polymerase Chain Reaction
  • Tranylcypromine / pharmacology

Substances

  • Histones
  • Interleukin-1beta
  • Monoamine Oxidase Inhibitors
  • Tranylcypromine
  • Pargyline
  • Histone Demethylases
  • KDM1A protein, human
  • Intramolecular Oxidoreductases
  • PTGES protein, human
  • Prostaglandin-E Synthases
  • Lysine