Background
Osteoarthritis (OA) is a leading cause of pain, disability, and reduced mobility worldwide, characterized by metabolic imbalances in chondrocytes, extracellular matrix (ECM), and subchondral bone. Emerging evidence highlights the critical role of long non-coding RNAs (lncRNAs) in OA pathogenesis. This study focuses on lncRNA PTS-1, a novel lncRNA, to explore its function and regulatory mechanisms in OA progression.
Conclusion
These findings identify lnc-PTS-1/miR-8085/E2F2 axis as a novel regulatory mechanism in OA pathogenesis, providing theoretical basis and experimental evidence for the potential clinical application of new lncRNA molecules in the treatment of OA.
Methods
The expression profile of lncRNAs was assessed using RNA sequencing and qRT-PCR. The expression of lnc-PTS-1 was further validated by qRT-PCR in degenerated cartilage tissues, degenerative primary chondrocytes, and IL-1β-treated C28/I2 cells. Cell viability, proliferation, and apoptosis rates, along with the mRNA and protein levels of apoptosis-related markers (cleaved Caspase 3, cleaved Caspase 9, Bcl-2, Bax), ECM metabolism markers (MMP-3, MMP-13, aggrecan, collagen II), and inflammation-related markers (IL-1β, IL-6, TNF-α) were evaluated using Cell Counting Kit-8, Toluidine Blue staining, Alcian Blue staining, flow cytometry, qRT-PCR, immunofluorescence, and Western Blot. The interaction between miR-8085 and lnc-PTS-1 or E2F2 was investigated through dual luciferase reporter assays and RNA immunoprecipitation (RIP) analyses.
Results
Lnc-PTS-1 expression was significantly downregulated in degenerated cartilage tissues, IL-1β-induced degenerative primary chondrocytes and C28/I2 cells. Functional experiments showed that lnc-PTS-1 knockdown aggravated IL-1β-induced ECM degradation, chondrocyte apoptosis, and inflammation, while its overexpression provided protective effects. Mechanistically, lnc-PTS-1 acted as a competing endogenous RNA (ceRNA) by sponging miR-8085, thereby upregulating E2F2 expression. Notably, miR-8085 upregulation diminished the protective effects of lnc-PTS-1 on ECM degradation, apoptosis, and inflammation, while E2F2 upregulation partially alleviated IL-1β-induced damage. However, these mitigating effects were reversed by miR-8085 overexpression.