Evaluation of MiR-181a as a potential therapeutic target in osteoarthritis

Purpose: To investigate microRNA-181 (miR-181) as a potential therapeutic target in osteoarthritis (OA).
Methods: MiR-181 expression was evaluated in articular cartilage samples obtained from OA patients undergoing knee arthroplasty and non-OA (control) patients undergoing other orthopedic procedures. Following the isolation of total RNA, miRNA and mRNA expression was determined by real time-polymerase chain reaction (RT-PCR). Luciferase reporter assay and miRNA mimic or inhibitor were then used to establish the molecular target of miR-181 in chondrocytes.
Results: miR-181 family members, namely, miR-181a, miR-181c and miR-181d were significantly upregulated in articular cartilage obtained from OA patients compared to non-OA control subjects. However, no significant difference in up-regulation of miR-181b expression. B-cell lymphoma 2 (BCL2), a putative target of the miR-181 family, was significantly down-regulated in OA patients compared to control subjects. Furthermore, luciferase reporter assay confirmed direct interaction between miR-181a and three prime untranslated region The 3’UTR of BCL2 in chondrocytes. Transfection of miR-181 mimic resulted in BCL2 suppression in chondrocytes. On the other hand, transfection of miR-181 inhibitor led to increased BCL2 expression and decreased interleukin 1-beta (IL1-β) induced apoptosis.
Conclusion: miR-181 is differentially expressed in articular cartilage of OA patients and leads to down-regulation of BCL2, a regulator of apoptosis. Therefore, miR-181 may be a potential therapeutic target in the treatment of OA.

Keywords
MicroRNA; Osteoarthritis; Apoptosis; B-cell lymphoma 2; Transfection; Chondrocytes