M6A-mediated upregulation of AC008 promotes osteoarthritis progression through the miR-328-3p\u2012AQP1/ANKH axis

Jiashu Yang,Yunfei Ma,Li Chen,Changyan Ma,Ming Zhang,Yuting Tang,Yucui Jin,Lingyun Li,Mengying Xing,Dawei Yang

doi:10.1038/s12276-021-00696-7

Abstract

Long noncoding RNAs (lncRNAs) have emerged as important regulators of osteoarthritis (OA), but the biological roles and clinical significance of most lncRNAs in OA are not fully understood. Microarray analysis was performed to identify differentially expressed lncRNAs, mRNAs, and miRNAs between normal and osteoarthritic cartilage. We found that AC008440.5 (abbreviated AC008), as well as AQP1 and ANKH, were highly expressed in osteoarthritic cartilage, whereas miR-328-3p was expressed at a low level in osteoarthritic cartilage. Functional assays showed that ectopic expression of AC008, AQP1, and ANKH significantly decreased chondrocyte viability and promoted chondrocyte apoptosis and extracellular matrix (ECM) degradation, whereas knockdown of AC008, AQP1, and ANKH resulted in the opposite effects. Moreover, miR-328-3p overexpression increased chondrocyte viability and attenuated chondrocyte apoptosis and ECM degradation, whereas inhibition of miR-328-3p resulted in the opposite effects. Bioinformatics analysis, RNA immunoprecipitation (RIP), and luciferase assays revealed that AC008 functioned as a competing endogenous RNA (ceRNA) to regulate miR-328-3p, which specifically targeted the AQP1 and ANKH genes. In addition, miR-328-3p significantly ameliorated MIA-induced OA, whereas AC008 accelerated OA progression in vivo. Furthermore, fat mass and obesity-associated (FTO)-mediated N6-methyladenosine demethylation downregulated AC008 transcription, while lower FTO expression led to upregulation of AC008 transcription in OA. In conclusion, our data reveal that AC008 plays a critical role in OA pathogenesis via the miR-328-3p‒AQP1/ANKH pathway, suggesting that AC008 may be a potential therapeutic target for OA.

Highlights

Osteoarthritis (OA) is an age-related or posttraumatic degenerative joint disease[1] that is characterized by extracellular matrix (ECM) degradation, chondrocyte hypertrophy, and apoptosis[2,3,4]
Functional assays showed that ectopic expression of AC008, AQP1, and ANKH significantly decreased chondrocyte viability and promoted chondrocyte apoptosis and ECM degradation, whereas knockdown of AC008, AQP1, and ANKH resulted in the opposite effects
AC008 is highly expressed in human osteoarthritic cartilage We performed microarray analyses to identify the differentially expressed Long noncoding RNAs (lncRNAs), mRNAs, and miRNAs between normal and osteoarthritic articular cartilage

Summary

Introduction

Osteoarthritis (OA) is an age-related or posttraumatic degenerative joint disease[1] that is characterized by extracellular matrix (ECM) degradation, chondrocyte hypertrophy, and apoptosis[2,3,4]. MicroRNAs (miRNAs), a class of small noncoding RNAs ~22 nucleotides in length, negatively regulate target gene expression either by inhibiting mRNA translation or by promoting mRNA degradation. A growing body of evidence indicates that dysregulation of lncRNAs is involved in the progression of OA by affecting various essential cellular features of chondrocytes, such as their proliferation, apoptosis, inflammation, and ability to contribute to ECM degradation[12,13]. HOTAIR aggravates ECM degradation and chondrocyte apoptosis by sponging miR-17-5p and upregulating FUT2 expression[14]. LncRNA-XIST promotes OA progression by regulating chondrocyte viability, chondrocyte apoptosis, and ECM degradation. LncRNA-XIST functions as a competing endogenous RNA (ceRNA) by competing for binding with miR-149-5p to regulate DNMT3A expression[15]

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Results

Conclusion