N⁶‐methyladenosine‐modified circRNA RERE modulates osteoarthritis by regulating β‐catenin ubiquitination and degradation

Abstract

Objectives N6‐methyladenosine (m6A) is one of the most abundant internal RNA modifications. We investigated the role of m6A‐modified circRERE in osteoarthritis (OA) and its mechanism. Materials and Methods CircRERE and IRF2BPL were screened by microarrays. The role of m6A‐modification in circRERE was examined by methylated RNA precipitation and morpholino oligo (MOs) treatment. The axis of circRERE/miR‐195‐5p/IRF2BPL/β‐catenin was determined using flow cytometry, western blotting and immunofluorescence in human chondrocytes (HCs) and corroborated using a mouse model of destabilization of medial meniscus (DMM) with intra‐articular (IA) injection of adeno‐associated viruses (AAV). Results CircRERE was decreased in OA cartilage and chondrocytes compared with control. CircRERE downregulation was likely attributed to its increased m6A modification prone to endoribonucleolytic cleavage by YTHDF2‐HRSP12‐RNase P/MRP in OA chondrocytes. MOs transfection targeting HRSP12 binding motifs in circRERE partially reversed decreased circRERE expression and increased apoptosis in HCs treated with IL‐1β for 6 h. CircRERE exerted chondroprotective effects by targeting miR‐195‐5p/IRF2BPL, thus regulating the ubiquitination and degradation of β‐catenin. CircRere (mouse homologue) overexpression by IA‐injection of AAV‐circRere into mice attenuated the severity of DMM‐induced OA, whereas AAV‐miR‐195a‐5p or AAV‐sh‐Irf2bpl reduced the protective effects. The detrimental effects of AAV‐sh‐Irf2bpl on DMM‐induced OA were substantially counteracted by ICG‐001, an inhibitor of β‐catenin. Conclusions Our study is a proof‐of‐concept demonstration for targeting m6A‐modified circRERE and its target miR‐195‐5p/IRF2BPL/β‐catenin as potential therapeutic strategies for OA treatment.

YTHDF2-mediated circYAP1 drives immune escape and cancer progression through activating YAP1/TCF4-PD-L1 axis

“…N6-methyladenosine methylation has been reported to be involved in aberrant circRNA expression. 22 To explore the role of m6A in circYAP1 dysregulation, we predicted that m6A modifications are present in circYAP1 ( http://www.cuilab.cn/sramp ) ( Figure 8 A). Next, methylated RNA immunoprecipitation (MeRIP)-qPCR results indicated that circYAP1 could be specifically enriched by the anti-m6A antibody in HCT116 cells ( Figure 8 B).…”

Elucidating the role of ubiquitination and deubiquitination in osteoarthritis progression

“…AC008 was increased after m6A modification, leading to accelerating osteoarthritis progression via modulation of miR-328-3p and AQP1/ANKH pathways (155). One study implicated that m6A (N 6 -methyladenosine)-modified circRNA RERE regulated osteoarthritis via control of b-catenin ubiquitination and degradation (156).…”

Update on N6‐methyladenosine methylation in obesity‐related diseases

“…METTL3 inhibited inflammation‐induced chondrocyte apoptosis and autophagy through the m6A/YTHDF1/Bcl2 signaling pathway [77]. Liu et al reported that m6A modification enhanced the endoribonucleolytic cleavage of CircRERE, thereby resulting in the downregulation of CircRERE in the human and murine OA chondrocytes and impairing the cartilage‐protecting effects of CircRERE [93]. Furthermore, m6A regulators such as ALKBH1, eIF3, IGF2BP3, WTAP, and YTHDC1 were differentially expressed in the patients with OA compared with the patients without OA [94].…”