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Abstract
Objectives In osteoarthritis, methylation of lysine 79 on histone H3 (H3K79me), a protective epigenetic mechanism, is reduced. Histone methylation levels are dynamically regulated by histone methyltransferases and demethylases. Here, we aimed to identify which histone demethylases regulate H3K79me in cartilage and investigate whether their targeting protects against osteoarthritis.
Methods We determined histone demethylase expression in human non-osteoarthritis and osteoarthritis cartilage using qPCR. The role of histone demethylase families and subfamilies on H3K79me was interrogated by treatment of human C28/I2 chondrocytes with pharmacological inhibitors, followed by western blot and immunofluorescence. We performed C28/I2 micromasses to evaluate effects on glycosaminoglycans by Alcian blue staining. Changes in H3K79me after destabilisation of the medial meniscus (DMM) in mice were determined by immunohistochemistry. Daminozide, a KDM2/7 subfamily inhibitor, was intra-articularly injected in mice upon DMM. Histone demethylases targeted by daminozide were individually silenced in chondrocytes to dissect their role on H3K79me and osteoarthritis.
Results We documented the expression signature of histone demethylases in human non-osteoarthritis and osteoarthritis articular cartilage. Inhibition of Jumonji-C demethylase family increased H3K79me in human chondrocytes. Blockade of KDM2/7 histone demethylases with daminozide increased H3K79me and glycosaminoglycans. In mouse articular cartilage, H3K79me decayed rapidly upon induction of joint injury. Early and sustained intra-articular treatment with daminozide enhanced H3K79me and exerted protective effects in mice upon DMM. Individual silencing of KDM7A/B demethylases in human chondrocytes demonstrated that KDM7A/B mediate protective effects of daminozide on H3K79me and osteoarthritis.
Conclusion Targeting KDM7A/B histone demethylases could be an attractive strategy to protect joints against osteoarthritis.
- Osteoarthritis
- Chondrocytes
- Arthritis, Experimental
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Data are available on reasonable request.
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Footnotes
RA and CC are joint first authors.
RJL and SM are joint senior authors.
Handling editor Josef S Smolen
Correction notice This article has been corrected since it published Online First. The funding statement has been updated.
Contributors SM and RJL are the senior authors of this study and article. SM and RJL formulated the original research hypothesis and elaborated the ideas into the grant proposals that supported this work. They contributed to the design of all experiments, all analyses and verified the results. RA and CC are joint first authors of the manuscript. The order on the paper is alphabetic. CC initiated the experimental work as postdoctoral researcher in the team led by SM and RJL, designed, planned, performed in vitro experiments. CC trained new Ph.D researcher RA who took over the experimental design, planning, performance and analysis after CC moved to another lab after her postdoctoral fellowship. RA, CC, SM and RJL wrote the manuscript. FMFC, RJL and SM designed and performed the animal experiments. FMFC, QZ and LS performed the ex vivo analysis. RCdA and IM performed the analysis of the RAAK study. RA, SP, QZ and CC performed data analysis and graphical presentation of the data. RJL accepts full responsibility for the work and/or the conduct of the study, had access to the data and controlled the decision to publish.
Funding This work was supported by grants from the Flanders Research Foundation (FWO-Vlaanderen) (G0B2120N, G097118N and G059223N) and Excellence of Science (G0F8218N, Joint-against-OA). RA is recipient of a strategic basic research PhD fellowship from FWO-Vlaanderen (1SF4522N). RJL is the recipient of a senior clinical research fellowship from FWO-Vlaanderen (18B2122N). The RAAK study is supported by Leiden University Medical Center. Research leading to the RAAK study results has received funding from the Dutch Arthritis Association (DAA 2010_017) and the IDEAL project (European Union’s Seventh Framework Program (FP7/2007–2011) under grant agreement no. 259679).
Competing interests Leuven Research and Development, the technology transfer office of KU Leuven, has received consultancy and speaker fees and research grants on behalf of RJL from Abbvie, Boehringer-Ingelheim, Celgene, Eli-Lilly, Galapagos, Janssen, Fresenius Kabi, MSD, Novartis, Pfizer, Biosplice Therapeutics (formerly Samumed) and UCB. The other authors declare that they have no competing financial interests.
Patient and public involvement Patients and/or the public were not involved in the design, or conduct, or reporting, or dissemination plans of this research.
Provenance and peer review Not commissioned; externally peer reviewed.
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