Long non-coding RNA CIR inhibits chondrogenic differentiation of mesenchymal stem cells by epigenetically suppressing ATOH8 via methyltransferase EZH2

Feng Liu,Hong-Qi Yang,Jiang-Dong Ni,De-Ye Song,Di You,Jun Huang

doi:10.1186/s10020-021-00272-9

Abstract

BackgroundOsteoarthritis (OA) is the most common articular disorder, leading to joint malfunction and disability. Although the incidence of OA is increasing globally, the treatment of OA is very limited. LncRNA CIR has been implicated in OA through unclear mechanisms. Here, we investigated the role of lncRNA CIR in chondrogenic differentiation.MethodsHuman umbilical-cord-derived mesenchymal stem cells (hUC-MSCs) were obtained from human umbilical cords. Flow cytometry was used to analyze the surface markers of hUC-MSCs. Various culture conditions and corresponding staining assays were employed to assess the differentiation abilities of hUC-MSC. qRT-PCR, western blot, and immunostaining were used to measure expression levels of related genes and proteins such as lncRNA CIR, ATOH8, EZH2, and H3K27me3. RNA immunoprecipitation assay, biotin pull-down, and chromatin immunoprecipitaion assay were performed to analyze the interactions of lncRNA CIR, EZH2, H3K27me3 and ATOH8 promoter.ResultshUC-MSCs exhibited MSCs features and could differentiate into chondrocytes under specific conditions. LncRNA CIR was downregulated while ATOH8 was upregulated during the chondrogenic differentiation of hUC-MSCs. Knockdown lncRNA CIR or overexpression of ATOH8 promoted chondrogenic differentiation. Further, lncRNA CIR bound to EZH2 and repressed ATOH8 expression via EZH2-mediated H3K27me3, which promotes the methylation of ATOH8. Inhibition of ATOH8 reversed the effects of knockdown lncRNA CIR on chondrogenic differentiation.ConclusionLncRNA CIR suppresses chondrogenic differentiation of hUC-MSCs. Mechanistically, lncRNA CIR could inhibit ATOH8 expression that functions to promote chondrogenic differentiation through EZH2-mediated epigenetic modifications.

Highlights

Osteoarthritis (OA) is a very common but complex chronic degenerative disease characterized byLiu et al Mol Med (2021) 27:12The pathogenesis of OA is complicated and multifactorial, which is mainly associated with age-related loss of homeostatic balance (Martel-Pelletier 2016)
We found that Long non-coding RNAs (lncRNAs) CIR was reduced while Atonal homolog 8 (ATOH8) was increased during chondrogenic differentiation of hUC-mesenchymal stem cells (MSCs)
Cells transfected with si-CIR had much lower level of lncRNA CIR compared with control cells or cells transfected with si-NC Fig. 2d

Summary

Introduction

Osteoarthritis (OA) is a very common but complex chronic degenerative disease characterized byLiu et al Mol Med (2021) 27:12The pathogenesis of OA is complicated and multifactorial, which is mainly associated with age-related loss of homeostatic balance (Martel-Pelletier 2016). Emerging evidence has shown that mesenchymal stem cells (MSCs) could be used for cartilage repair in that they are multipotent stromal cells and can differentiate into varieties of cell types, including chondrocytes (Chang et al 2016; Ullah et al 2015; Fahy et al 2018). Bone marrow MSCs are the most common source of MSCs and can promptly boost the cartilage regeneration (Richardson 2016; Gugjoo et al 2016). Human umbilical-cord-derived MSCs (hUCMSCs) are another attractive source that could be potentially used for OA treatment and they are easy to obtain and store (Ding et al 2015; Wang 2018). The mechanisms underlying the chondrocyte differentiation of hUC-MSCs remains largely unknown. We investigated the role of lncRNA CIR in chondrogenic differentiation

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Results

Conclusion