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Epigenetic regulation of cyclooxygenase-2 by methylation of c8orf4 in pulmonary fibrosis
- Source :
- Clinical Science (London, England : 1979)
- Publication Year :
- 2016
- Publisher :
- Portland Press Ltd., 2016.
-
Abstract
- The present study demonstrates that hypermethylation and silencing of chromosome 8 open reading frame 4 (thyroid cancer protein 1, TC-1) (c8orf4), a transcriptional regulator of cyclooxygenase-2 (COX-2), is a major contributor to failure of fibroblasts to up-regulate COX-2 in pulmonary fibrosis. DNA methyltransferase (DNMT) inhibition reduces c8orf4 methylation, restores COX-2 expression and normalizes fibroblast function.<br />Fibroblasts derived from the lungs of patients with idiopathic pulmonary fibrosis (IPF) and systemic sclerosis (SSc) produce low levels of prostaglandin (PG) E2, due to a limited capacity to up-regulate cyclooxygenase-2 (COX-2). This deficiency contributes functionally to the fibroproliferative state, however the mechanisms responsible are incompletely understood. In the present study, we examined whether the reduced level of COX-2 mRNA expression observed in fibrotic lung fibroblasts is regulated epigenetically. The DNA methylation inhibitor, 5-aza-2′-deoxycytidine (5AZA) restored COX-2 mRNA expression by fibrotic lung fibroblasts dose dependently. Functionally, this resulted in normalization of fibroblast phenotype in terms of PGE2 production, collagen mRNA expression and sensitivity to apoptosis. COX-2 methylation assessed by bisulfite sequencing and methylation microarrays was not different in fibrotic fibroblasts compared with controls. However, further analysis of the methylation array data identified a transcriptional regulator, chromosome 8 open reading frame 4 (thyroid cancer protein 1, TC-1) (c8orf4), which is hypermethylated and down-regulated in fibrotic fibroblasts compared with controls. siRNA knockdown of c8orf4 in control fibroblasts down-regulated COX-2 and PGE2 production generating a phenotype similar to that observed in fibrotic lung fibroblasts. Chromatin immunoprecipitation demonstrated that c8orf4 regulates COX-2 expression in lung fibroblasts through binding of the proximal promoter. We conclude that the decreased capacity of fibrotic lung fibroblasts to up-regulate COX-2 expression and COX-2-derived PGE2 synthesis is due to an indirect epigenetic mechanism involving hypermethylation of the transcriptional regulator, c8orf4.
- Subjects :
- Male
Genotype
Transcription, Genetic
systemic sclerosis
Pulmonary Fibrosis
Down-Regulation
S8
Transfection
fibroblast
Dinoprostone
Epigenesis, Genetic
Humans
RNA, Messenger
Enzyme Inhibitors
Promoter Regions, Genetic
DNA Modification Methylases
Lung
Cells, Cultured
Aged
Cell Proliferation
Original Paper
prostaglandin E2
DNA methylation
Binding Sites
Scleroderma, Systemic
Dose-Response Relationship, Drug
11 Medical And Health Sciences
Fibroblasts
Middle Aged
idiopathic pulmonary fibrosis
Original Papers
Neoplasm Proteins
Gene Expression Regulation, Neoplastic
Phenotype
Cardiovascular System & Hematology
cyclooxygenase-2
Cyclooxygenase 2
Case-Control Studies
Female
RNA Interference
Subjects
Details
- Language :
- English
- ISSN :
- 14708736 and 01435221
- Volume :
- 130
- Issue :
- 8
- Database :
- OpenAIRE
- Journal :
- Clinical Science (London, England : 1979)
- Accession number :
- edsair.pmid.dedup....161b3d73204929cee8750a69b806cc91