Long Noncoding RNA GAS5 Inhibits Osteogenic Differentiation through MicroRNA 382-3p/TAF1 Signaling

Long noncoding RNAs (lncRNAs) have been confirmed as important regulators during osteogenic differentiation. Previous research has disclosed that growth arrest-specific transcript 5 (GAS5) can promote osteogenic differentiation of human bone marrow mesenchymal stem cells (hBMSCs), but the underlying regulatory mechanism of GAS5 during the osteogenic differentiation of hBMSCs is unclear. Osteogenic differentiation was induced in hBMSCs by using osteogenic medium (OM). Gene expression was assessed by quantitative real-time PCR (RT-qPCR) or Western blot assays as needed. Alkaline phosphatase (ALP) activity, ALP staining, and alizarin red S (ARS) staining assays were performed to evaluate the impact of GAS5, microRNA 382-3p (miR-382-3p), and TATA box binding protein-associated factor 1 (TAF1) on osteogenic differentiation in vitro. The interaction among GAS5, miR-382-3p, and TAF1 was determined by RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP), and luciferase reporter assays. Expression of GAS5 (transcript variant 2) was downregulated during the osteogenic differentiation of hBMSCs, and its overexpression retarded the osteogenic differentiation of hBMSCs. GAS5 inhibited miR-382-3p by targeting RNA-directed microRNA degradation (TDMD). miR-382-3p downregulation partially offset the promoted osteogenic differentiation of hBMSCs upon GAS5 silencing. TAF1 negatively modulated osteogenic differentiation, and it activated GAS5 transcription so as to form a positive GAS5-miR-382-3p-TAF1 feedback loop in hBMSCs. This research was the first to reveal that the GAS5-miR-382-3p-TAF1 feedback loop inhibited the osteogenic differentiation of hBMSCs, which provided new clues for exploring the mechanism of osteogenic differentiation and disclosed the potential of GAS5 as a promising target during osteogenic differentiation.