SOX4 accelerates intervertebral disc degeneration via EZH2/NRF2 pathway in response to mitochondrial ROS-dependent NLRP3 inflammasome activation in nucleus pulposus cells

J Transl Med. 2025 Apr 3;23(1):395. doi: 10.1186/s12967-024-05913-1.

Abstract

Objective: The transcription factor SRY-related HMG-box 4 (SOX4) has been implicated in intervertebral disc diseases. This study aimed to investigate the role of SOX4 in intervertebral disc degeneration (IDD) and explore the underlying molecular mechanisms.

Methods: We established an IDD rat model via surgery and analyzed SOX4 expression using qRT-PCR and Western blotting. Histological evaluation, immunohistochemistry, and Safranin O staining assessed IDD progression. In vitro, an IDD cellular model was constructed using IL-1β-stimulated nucleus pulposus (NP) cells. SOX4 knockdown and overexpression experiments in NP cells examined SOX4 effects on ECM degradation, NLRP3-mediated pyroptosis, and mitochondrial ROS-dependent NLRP3 inflammasome activation. The involvement of the EZH2/NRF2 pathway in SOX4-mediated NLRP3 activation was also examined.

Results: SOX4 expression was significantly increased in IDD rats and promoted IDD progression. Knockdown of SOX4 inhibited ECM degradation and NLRP3-mediated pyroptosis in NP cells. In vitro experiments showed that SOX4 promoted ECM degradation by upregulating MMPs and ADAMTS-5 expression, and suppressed collagen II and aggrecan synthesis. SOX4 knockdown inhibited NLRP3-mediated pyroptosis, while overexpression accelerated it in NP cells. Additionally, SOX4 was found to exacerbate mitochondrial ROS-dependent NLRP3 inflammasome activation in NP cells. Further investigation revealed that SOX4 enhanced NLRP3 inflammasome activation by upregulating EZH2 expression and modulating the EZH2/NRF2 pathway, with EZH2 inhibition attenuating SOX4-induced NLRP3 activation.

Conclusion: Our findings suggest that SOX4 accelerates IDD progression by promoting NLRP3 inflammasome activation via modulating the EZH2/NRF2 pathway, leading to NP cell pyroptosis and ECM degradation. Targeting SOX4 may represent a potential therapeutic strategy for treating IDD.

Keywords: EZH2/NRF2 pathway; Extracellular matrix degradation; Intervertebral disc degeneration; NLRP3 inflammasome activation; Pyroptosis; SRY-related HMG-box 4.

MeSH terms

  • Animals
  • Enhancer of Zeste Homolog 2 Protein* / metabolism
  • Extracellular Matrix / metabolism
  • Inflammasomes* / metabolism
  • Intervertebral Disc Degeneration* / metabolism
  • Intervertebral Disc Degeneration* / pathology
  • Male
  • Mitochondria* / metabolism
  • NF-E2-Related Factor 2* / metabolism
  • NLR Family, Pyrin Domain-Containing 3 Protein* / metabolism
  • Nucleus Pulposus* / metabolism
  • Nucleus Pulposus* / pathology
  • Pyroptosis
  • Rats
  • Rats, Sprague-Dawley
  • Reactive Oxygen Species* / metabolism
  • SOXC Transcription Factors* / metabolism
  • Signal Transduction*

Substances

  • Enhancer of Zeste Homolog 2 Protein
  • Reactive Oxygen Species
  • NLR Family, Pyrin Domain-Containing 3 Protein
  • NF-E2-Related Factor 2
  • Inflammasomes
  • SOXC Transcription Factors
  • Nlrp3 protein, rat
  • EZH2 protein, rat
  • Nfe2l2 protein, rat