LAUSR

4 Background: Long non-coding RNAs (lncRNAs) were identified as an important 5 regulator involved in the pathogenesis of osteoarthritis (OA). We aimed to evaluate 6 whether lncRNA GACAT3 regulate OA progression by miR-195/TGF-β/Smad5 axis. 7 Methods: Expression levels in tissue or chondrocytes were detected by RT-qPCR and 8 Western blot. Effects of GACAT3 on cell viability, proliferation, apoptosis were 9 evaluated. Targeted interactions of GACAT3, miR-195 and Smad5 were confirmed by 10 dual luciferase reporter gene assay and biotin-coupled miRNA capture assay. 11 Transfected or non-transfected cells were treated with TGF-β1 to verify role of TGF-β 12 in mechanisms of OA progression. 13 Results: GACAT3 was overexpressed in OA tissues and associated with OA severity. 14 After GACAT3 overexpression, the ability of cell viability and proliferation as well as 15 proliferation-related genes was inhibited with enhanced level of apoptosis-related genes 16 and Smad5. miR-195-5p was negatively targeted by GACAT3 and reversed effects 17 caused by GACAT3. miR-195-5p negatively targeted Smad5. In the presence of TGF18 β1, miR-195-5p mimics inhibited activation of Smad1/5, Smad5 and Smad2 compared 19 with negative control. Immunofluorescence showed that miR-195-5p inhibited 20 Pr ep rin t