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


CONCLUSIONS
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.
El Mansouri
Fatima Ezzahra
FE
Research Centre of the University of Montreal Hospital Centre, Notre-Dame Hospital, and University of Montreal, Montreal, Quebec, Canada.
Chabane
Nadir
N
Zayed
Nadia
N
Kapoor
Mohit
M
Benderdour
Mohamed
M
Martel-Pelletier
Johanne
J
Pelletier
Jean-Pierre
JP
Duval
Nicolas
N
Fahmi
Hassan
H
D000328:Adult; D000368:Aged; D015153:Blotting, Western; D002356:Cartilage / Q000187:drug effects / Q000378:metabolism; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D047369:Chromatin Immunoprecipitation; D051546:Cyclooxygenase 2 / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression / Q000187:drug effects; D020868:Gene Silencing; D011495:Histone-Lysine N-Methyltransferase / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D007375:Interleukin-1 / Q000378:metabolism / Q000494:pharmacology*; D008745:Methylation; D008875:Middle Aged; D052247:Nitric Oxide Synthase Type II / Q000235:genetics / Q000378:metabolism*; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D018709:Statistics, Nonparametric
D007375:Interleukin-1; D012333:RNA, Messenger; D052247:Nitric Oxide Synthase Type II; D051546:Cyclooxygenase 2; D011495:Histone-Lysine N-Methyltransferase; C526068:Setd1A protein, human