m6A-mediated upregulation of AC008 promotes osteoarthritis progression through the miR-328-3p‒AQP1/ANKH axis

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.

m6A Regulator-Mediated RNA Methylation Modification Patterns Regulate the Immune Microenvironment in Osteoarthritis

“…Previous studies have shown that m6A regulatory factors, especially METTL3 and FTO , are involved in OA progression via the regulation of inflammatory response and extracellular matrix degradation. On the one hand, FTO-dependent m6A demethylation mediates the upregulation of AC008 , which inhibits chondrocyte viability and promotes chondrocyte apoptosis and ECM degradation in OA ( Yang et al, 2021 ). On the other hand, METTL3 affects the stability of autophagy-related 7 ( ATG7 ) mRNA, thereby influencing autophagic activity in an m6A- YTHDF2-dependent manner.…”

Regulatory Role of N6-Methyladenosine (m6A) Modification in Osteoarthritis

“…To investigate the specific regulatory mechanism of AC008, miR-328-3p was suggested to be the target of AC008 by bioinformatics analysis and dual luciferase reporter gene assay; while AQP1 and ANKH were the targets of miR-328-3p. In addition, the study verified the reversal of chondrocyte apoptosis by decreasing m6A levels of AC008 after FTO overexpression in chondrocytes, and finally concluded that FTO-dependent m6A demethylation-mediated upregulation of AC008 promotes osteoarthritis progression through the miR-328-3p-AQP1/ANKH axis ( Yang et al, 2021 ).…”

Novel insights into the interaction between N6‐methyladenosine methylation and noncoding RNAs in musculoskeletal disorders

“…77 Studies confirmed that some m6A-related proteins in ncRNA are abnormally expressed and participate in the occurrence and development of musculoskeletal diseases by modulating the homoeostasis of skeletal muscle, bone and cartilage. 32,187 However, the regulatory mechanism of ncRNA m6A modification is still unclear.…”