Kdm6b regulates cartilage development and homeostasis through anabolic metabolism.
OBJECTIVE
Epigenetic mechanisms have been reported to play key roles in chondrogenesis and osteoarthritis (OA) development. Here, we sought to identify specific histone demethylases that are involved and delineate the underlying mechanisms.


METHODS
We screened the expression of 17 distinct histone demethylases by quantitative real time PCR (qRT-PCR) during chondrogenic differentiation of C3H10T1/2 cells. The role of Kdm6b in cartilage development was then analysed with transgenicCol2a1-CreERT2;Kdm6bf/f. RNA-Seq was applied to explore the underlying changes in chondrocytes upon knockdown of Kdm6b. Experimental OA in mice was induced by destabilisation of the medial meniscus in C57BL/6J (wild type,Kdm6bf/fandCol2a1-CreERT2;Kdm6bf/f) mice, either with intra-articular injection of shKdm6b lentivirus or after tamoxifen treatment. Mouse joints and human cartilage samples were used for histological analysis.


RESULTS
Kdm6b expression was significantly increased during cartilage development.Col2a1-CreERT2;Kdm6bf/fmice displayed obvious skeletal abnormalities at E16.5 and E18.5 with intraperitoneal injection of tamoxifen at E12.5. RNA-Seq and qRT-PCR analyses revealed decreased expression of chondrocyte anabolic genes inCol2a1-CreERT2;Kdm6bf/fchondrocytes. The histological OA score was significantly higher in mice injected with Kdm6b short hairpin RNA lentivirus.Col2a1-CreERT2;Kdm6bf/fmice exhibited accelerated OA development at 8 and 12 weeks following surgical induction. The number of Kdm6b-positive chondrocytes was lower in both mice and human OA cartilage samples.


CONCLUSIONS
These findings indicate that knockdown of Kdm6b in chondrocytes leads to abnormal cartilage development and accelerated OA progression via inhibition of the anabolic metabolism of chondrocytes. Understanding the epigenetic mechanism of joint cartilage development and homeostasis would be useful for development of new therapeutic modalities for OA.
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Jun
J
Dai
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.|Department of Sports Medicine, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.
Dongsheng
D
Yu
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Yafei
Y
Wang
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Yishan
Y
Chen
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Heng
H
Sun
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Xiaolei
X
Zhang
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Shouan
S
Zhu
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Zongyou
Z
Pan
Endodontology, Faculty of Dentistry, The University of Hong Kong, Pokfulam, Hong Kong.
Boon Chin
BC
Heng
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.
Shufang
S
Zhang
Dr. Li Dak Sum & Yip Yio Chin Center for Stem Cell and Regenerative Medicine, School of Medicine, Zhejiang University, Zhejiang, China.|Key Laboratory of Tissue Engineering and Regenerative Medicine of Zhejiang Province, School of Medicine, Zhejiang University, Zhejiang, China.|Department of Sports Medicine, School of Medicine, Zhejiang University, Hangzhou, Zhejiang, China.|State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, Collaborative Innovation Center for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, School of Medicine, Zhejiang University, Hangzhou, China.|China Orthopedic Regenerative Medicine Group, Hangzhou, China.
Hongwei
http://orcid.org/0000-0003-0627-2536
H
Ouyang
D000368:Aged; D000818:Animals; D015153:Blotting, Western; D002356:Cartilage / Q000378:metabolism; D002358:Cartilage, Articular / Q000378:metabolism*; D002460:Cell Line; D019902:Chondrocytes / Q000378:metabolism*; D020219:Chondrogenesis / Q000235:genetics*; D004195:Disease Models, Animal; D005260:Female; D018507:Gene Expression Regulation, Developmental; D055785:Gene Knockdown Techniques; D056466:Histone Demethylases / Q000235:genetics; D006706:Homeostasis / Q000235:genetics; D006801:Humans; D056484:Jumonji Domain-Containing Histone Demethylases / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D008592:Menisci, Tibial / Q000601:surgery; D051379:Mice; D020370:Osteoarthritis, Knee / Q000235:genetics* / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
D056466:Histone Demethylases; D056484:Jumonji Domain-Containing Histone Demethylases; C524220:KDM6B protein, human; C523761:Kdm6b protein, mouse
Chondrocytes; Knee Osteoarthritis; Osteoarthritis