TEAD4 and RXRA Regulate the Function of Nucleus Pulposus Cells in Intervertebral Disc Degeneration Via the TNF-α/NF-κB Pathway: An Integrated Analysis of Single-Cell RNA-Seq, Bulk RNA-Seq, and In Vitro Validation.

Intervertebral disc degeneration (IDD) is a major risk factor for chronic low back pain, but the mechanisms driving its progression remain unclear. To address this gap, we integrated single-cell RNA sequencing (scRNA-seq) and bulk RNA sequencing analyses, combined with in vitro experiments, to investigate the roles of key transcription factors (TFs) in IDD. First, we analyzed the scRNA-seq dataset GSE244889 and bulk RNA dataset GSE15227. Using marker gene analysis, we identified eight cell clusters in nucleus pulposus (NP) tissues. Gene Set Enrichment Analysis (GSEA) was applied to both datasets to screen for enriched TFs: 20 TFs were identified in GSE244889 and 42 in GSE15227. Intersection of these results yielded 12 common TFs, including TEAD4 and RXRA. To validate these TFs, we established an interleukin-1β-induced senescent NP cell model and performed RT-qPCR. Results showed that FOSL2, HSF1, CEBPB, RXRA, and ESR1 were upregulated, while GATA3, TEAD4, JUN, FOXM1, and JUND were downregulated in senescent NP cells. Immunohistochemical staining of human NP tissues further revealed that RXRA expression was increased and TEAD4 expression was decreased in late-stage IDD compared to early-stage IDD. Correlation analysis demonstrated that RXRA was negatively correlated with Collagen II and positively correlated with matrix metalloproteinase 3, whereas TEAD4 showed the opposite correlation pattern. Additionally, GSEA and Kyoto Encyclopedia of Genes and Genomes pathway analysis indicated that the tumor necrosis factor-α/nuclear factor-κB (TNF-α/NF-κB) pathway was enriched in IDD. In conclusion, TEAD4 and RXRA play critical roles in IDD progression, likely by regulating NP cell behavior and extracellular matrix metabolism through the TNF-α/NF-κB pathway. These findings provide novel insights for developing targeted therapies for IDD.