LINC00324 induces nucleus pulposus cell apoptosis in intervertebral disc degeneration via miR-143-3p targeted TRAIL/DR4/DR5 axis

Intervertebral disc degeneration (IDD) serves as a predominant pathogenic driver of spinal degenerative diseases and low back pain. Long non-coding RNAs (lncRNAs) have emerged as important regulators involved in the pathogenesis of IDD. Despite this, the specific contributions of LINC00324, a particular lncRNA, to the advancement of IDD are not yet well understood. The study seeks to elucidate the functional role and explore the potential molecular mechanisms of LINC00324 in IDD. RT-qPCR was employed to analyze LINC00324, miR-143-3p, and TRAIL levels in intervertebral disc (IVD) tissues from IDD patients and control subjects, followed by correlation analysis. Bioinformatics tools, dual-luciferase reporter assays, and RNA pull-down experiments were conducted to validate the regulatory interactions within LINC00324/miR-143-3p/TRAIL in nucleus pulposus cells (NPCs). In vitro, NPCs were stimulated with lipopolysaccharide (LPS) to construct an IDD cell model. RT-qPCR, western blot, CCK-8 assay, and flow cytometry were utilized to evaluate the effects on the levels of LINC00324/miR-143-3p/TRAIL/DR4/DR5, as well as the proliferation and apoptosis of NPCs. Additionally, extracellular matrix (ECM)-related proteins and inflammatory factors were detected by western blot and ELISA, respectively. In vivo, a rat IDD model was established through fibroannular puncture. Radiological analysis (X-ray), HE staining, TUNEL staining, and western blot were used to assess disc structural changes, NPC apoptosis, and the levels of miR-143-3p/TRAIL/DR4/DR5 and apoptosis-related proteins. Clinical evidence showed that LINC00324 and TRAIL levels were increased, and miR-143-3p was decreased in IDD samples. miR-143-3p had the negative correlation coefficient with TRAIL and LINC00324. Furthermore, LINC00324 acted as a sponge for miR-143-3p, and miR-143-3p specifically attenuated the downstream of TRAIL level. In vitro, the LPS-induced IDD model showed decreased NPC viability, increased apoptosis, disrupted ECM metabolism (downregulated Collagen II and Aggrecan, upregulated MMP13), elevated inflammatory factors, and activated TRAIL/DR4/DR5 axis. Silencing LINC00324 or overexpressing miR-143-3p alleviated these pathological changes. Furthermore, miR-143-3p partially counteracted the promoting influences of LINC00324 overexpression on NPC apoptosis, ECM degradation, inflammatory response, and TRAIL/DR4/DR5 axis activation in the IDD model. In vivo, LINC00324 overexpression exacerbated IDD in rats (decreased disc height index, disrupted NPC tissue structure, enhanced NPC apoptosis, aggravated ECM degradation, inhibited miR-143-3p expression, and activated TRAIL/DR4/DR5 axis), while LINC00324 knockdown attenuated these degenerative changes. In conclusion, LINC00324 promotes IDD progression by inducing NPC apoptosis, disrupting ECM metabolism, and enhancing inflammatory response via sponging miR-143-3p to activate the TRAIL/DR4/DR5 axis. Not applicable.