Long non-coding RNA GRASLND enhances chondrogenesis via suppression of interferon type II signaling pathway

Long non-coding RNAs (lncRNAs) play critical roles in regulating gene expression and cellular processes; however, their roles in musculoskeletal development, disease, and regeneration remain poorly understood. Here, we identified a novel lncRNA, Glycosaminoglycan Regulatory ASsociated Long Non-coDing RNA (GRASLND), as a regulator of mesenchymal stem cell (MSC) chondrogenesis, and we investigated its basic molecular mechanism and its potential application towards regenerative medicine. GRASLND, a primate-specific lncRNA, is upregulated during MSC chondrogenesis and appears to act directly downstream of SRY-Box 9 (SOX9), but not Transforming Growth Factor Beta 3 (TGF-ß3). Utilizing the established model of pellet formation for MSC chondrogenesis, we showed that the silencing of GRASLNDresulted in lower accumulation of cartilage-like extracellular matrix, while GRASLND overexpression, either via transgene ectopic expression or by endogenous activation via CRISPR, significantly enhanced cartilage matrix production. GRASLND acts to inhibit IFN-? by binding to eukaryotic initiation factor-2 kinase PKR. We further demonstrated that GRASLND exhibited a protective effect in engineered cartilage against interferon type II, and that GRASLND exerted this effect similarly in engineered cartilage across different sources of progenitors. Our results indicate an important role of GRASLND in regulating stem cell chondrogenesis, as well as its therapeutic potential in the treatment of cartilage-related diseases, such as osteoarthritis. Overall design: High throughput RNA sequencing of day 21 mesenchymal stem cell pellets with shRNAs targeting GRASLND