Contribution of H3K4 methylation by SET-1A to interleukin-1-induced cyclooxygenase 2 and inducible nitric oxide synthase expression in human osteoarthritis chondrocytes

Arthritis Rheum. 2011 Jan;63(1):168-79. doi: 10.1002/art.27762.

Abstract

Objective: To investigate the role of histone H3 lysine 4 (H3K4) methylation in interleukin-1β (IL-1β)-induced cyclooxygenase 2 (COX-2) and inducible nitric oxide synthase (iNOS) expression in human osteoarthritic (OA) chondrocytes.

Methods: Chondrocytes were stimulated with IL-1, and the expression of iNOS and COX-2 messenger RNA and proteins was evaluated by real-time reverse transcriptase-polymerase chain reaction analysis and Western blotting, respectively. H3K4 methylation and the recruitment of the histone methyltransferases SET-1A and MLL-1 to the iNOS and COX-2 promoters were evaluated using chromatin immunoprecipitation assays. The role of SET-1A was further evaluated using the methyltransferase inhibitor 5'-deoxy-5'-(methylthio)adenosine (MTA) and gene silencing experiments. SET-1A level in cartilage was determined using immunohistochemistry.

Results: The induction of iNOS and COX-2 expression by IL-1 was associated with H3K4 di- and trimethylation at the iNOS and COX-2 promoters. These changes were temporally correlated with the recruitment of the histone methyltransferase SET-1A, suggesting an implication of SET-1A in these modifications. Treatment with MTA inhibited IL-1-induced H3K4 methylation as well as IL-1-induced iNOS and COX-2 expression. Similarly, SET-1A gene silencing with small interfering RNA prevented IL-1-induced H3K4 methylation at the iNOS and COX-2 promoters as well as iNOS and COX-2 expression. Finally, we showed that the level of SET-1A expression was elevated in OA cartilage as compared with normal cartilage.

Conclusion: These results indicate that H3K4 methylation by SET-1A contributes to IL-1-induced iNOS and COX-2 expression and suggest that this pathway could be a potential target for pharmacologic intervention in the treatment of OA and possibly other arthritic diseases.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Blotting, Western
  • Cartilage / drug effects
  • Cartilage / metabolism
  • Cells, Cultured
  • Chondrocytes / drug effects
  • Chondrocytes / metabolism*
  • Chromatin Immunoprecipitation
  • Cyclooxygenase 2 / genetics
  • Cyclooxygenase 2 / metabolism*
  • Gene Expression / drug effects
  • Gene Silencing
  • Histone-Lysine N-Methyltransferase / genetics
  • Histone-Lysine N-Methyltransferase / metabolism*
  • Humans
  • Immunohistochemistry
  • Interleukin-1 / metabolism
  • Interleukin-1 / pharmacology*
  • Methylation
  • Middle Aged
  • Nitric Oxide Synthase Type II / genetics
  • Nitric Oxide Synthase Type II / metabolism*
  • Osteoarthritis / genetics
  • Osteoarthritis / metabolism*
  • RNA, Messenger / genetics
  • RNA, Messenger / metabolism
  • Reverse Transcriptase Polymerase Chain Reaction
  • Statistics, Nonparametric

Substances

  • Interleukin-1
  • RNA, Messenger
  • Nitric Oxide Synthase Type II
  • Cyclooxygenase 2
  • Histone-Lysine N-Methyltransferase
  • Setd1A protein, human