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Increased DNA Methylation and Reduced Expression of Transcription Factors in Human Osteoarthritis Cartilage
Author(s) -
AlvarezGarcia Oscar,
Fisch Kathleen M.,
Wineinger Nathan E.,
Akagi Ryuichiro,
Saito Masahiko,
Sasho Takahisa,
Su Andrew I.,
Lotz Martin K.
Publication year - 2016
Publication title -
arthritis and rheumatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.106
H-Index - 314
eISSN - 2326-5205
pISSN - 2326-5191
DOI - 10.1002/art.39643
Subject(s) - dna methylation , methylation , cartilage , chondrocyte , biology , transcriptome , transcription factor , epigenetics , gene expression , transcription (linguistics) , microbiology and biotechnology , gene , genetics , anatomy , linguistics , philosophy
Objective To analyze the methylome of normal and osteoarthritic (OA) knee articular cartilage and to determine the role of DNA methylation in the regulation of gene expression in vitro. Methods DNA was isolated from human normal (n = 11) and OA (n = 12) knee articular cartilage and analyzed using the Infinium HumanMethylation450 BeadChip array. To integrate methylation and transcription, RNA sequencing was performed on normal and OA cartilage and validated by quantitative polymerase chain reaction. Functional validation was performed in the human TC28 cell line and primary chondrocytes that were treated with the DNA methylation inhibitor 5‐aza‐2′‐deoxycytidine (5‐aza‐dC). Results DNA methylation profiling revealed 929 differentially methylated sites between normal and OA cartilage, comprising a total of 500 individual genes. Among these, 45 transcription factors that harbored differentially methylated sites were identified. Integrative analysis and subsequent validation showed a subset of 6 transcription factors that were significantly hypermethylated and down‐regulated in OA cartilage ( ATOH8 , MAFF , NCOR2 , TBX4 , ZBTB16 , and ZHX2 ). Upon 5‐aza‐dC treatment, TC28 cells showed a significant increase in gene expression for all 6 transcription factors. In primary chondrocytes, ATOH8 and TBX4 were increased after 5‐aza‐dC treatment. Conclusion Our findings reveal that normal and OA knee articular cartilage have significantly different methylomes. The identification of a subset of epigenetically regulated transcription factors with reduced expression in OA may represent an important mechanism to explain changes in the chondrocyte transcriptome and function during OA pathogenesis.