MicroRNA-155 suppresses autophagy in chondrocytes by modulating expression of autophagy proteins

• Published in: Osteoarthritis and cartilage 2016-06, Vol.24 (6), p.1082-1091
• Main Authors: D'Adamo, S, Alvarez-Garcia, O, Muramatsu, Y, Flamigni, F, Lotz, M.K
• Format: Article
• Language: English
• Subjects: Autophagy; Cartilage; Cartilage, Articular; Cells, Cultured; Chondrocytes; Humans; MicroRNAs; Osteoarthritis; Rheumatology
• ISSN: 1063-4584; 1522-9653
• DOI: 10.1016/j.joca.2016.01.005

Summary Objective Autophagy dysfunction has been reported in osteoarthritis (OA) cartilage. The objective of this study was to investigate the role of microRNA-155 (miR-155), which is overexpressed in OA, in the regulation of autophagy in human chondrocytes. Design Rapamycin (50 nM) and 2-deoxyglucose (2-DG) (5 mM) were used to stimulate autophagy in primary human articular chondrocytes and in the T/C28a2 human chondrocyte cell line. Cells were transfected with LNA GapmeR or mimic specific for miR-155 and autophagy flux was assessed by LC3 western blotting and by Cyto-ID® dye quantification in autophagic vacuoles. Expression of predicted miR-155 targets in the autophagy pathway were analyzed by real-time PCR and western blotting. Results Autophagy flux induced by rapamycin and 2-DG was significantly increased by miR-155 LNA, and significantly decreased after miR-155 mimic transfection in T/C28a2 cells and in human primary chondrocytes. These effects of miR-155 on autophagy were related to suppression of gene and protein expression of key autophagy regulators including Ulk1, FoxO3, Atg14, Atg5, Atg3, Gabarapl1, and Map1lc3. Conclusion MiR-155 is an inhibitor of autophagy in chondrocytes and contributes to the autophagy defects in OA.