Circular RNA CircACAP2 regulates temporomandibular joint osteoarthritis via miR‐21‐5p/PLAG1 axis

Abstract Objectives The pathogenesis of temporomandibular joint osteoarthritis (TMJOA) remains not fully understood. Our previous studies demonstrated that miR‐21‐5p may participate in the TMJOA development and the interaction between circRNA‐ACAP2 (CircACAP2) and miR‐21‐5p. Our present study aimed to explore the biological functions and regulatory mechanisms of CircACAP2 in TMJOA. Materials and Methods The differential expression pattern of CircACAP2 in OA and normal tissues or cells was detected. CircACAP2 biological functions experiments were performed in chondrocytes by overexpression and interference techniques. The interaction of CircACAP2 with miR‐21‐5p and downstream target mRNA, polymorphic adenoma gene 1 (PLAG1), was predicted by bioinformatic databases and then demonstrated by dual‐luciferase reporter assay. The biological role of CircACAP2 in TMJOA was investigated and validated in a mouse model. Results The expression level of CircACAP2 was markedly reduced in OA cartilage and directly related to chondrocyte proliferation and apoptosis as well as ECM metabolism in the cartilage. CircACAP2 functioned in chondrocytes via targeting miR‐21‐5p and PLAG1. Overexpressing of CircACAP2 alleviated TMJOA in mouse models. Conclusions The present study unveiled that CircACAP2/miR‐21‐5p/PLAG1 axis may play an important regulatory role in TMJOA progression, which may highlight a potentially effective intervention and therapeutic strategy for the treatment of TMJOA.