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Updated: Jun 8, 2025
Software-Assisted Quantitative Measurement of Osteoarthritic Subchondral Bone Thickness
Published on: March 18, 2022
RIP1 inhibition reduces chondrocyte apoptosis through downregulating nuclear factor-kappa B signaling in a mouse
Hong Zhao1, Chenzhong Wang1, Bo Liu1
1Department of Orthopedic Surgery, Zhongshan Hospital, Fudan University, Shanghai, 200032, China.
Background:
Excessive chondrocyte death is a critical player in the process of osteoarthritis (OA). The present study was aimed to study the role of receptor-interacting serine/threonine kinase (RIP) 1-mediated signaling for programmed cell death in OA.
Methods:
In the present study, RIP1 protein expression was evaluated in mouse OA cartilage and cultured primary murine chondrocytes exposed to tumor necrosis factor-alpha (TNF-α). Protein expression involved in necroptosis and apoptosis and chondrocyte-derived extracellular matrix were examined. Inhibition of RIP1 was conducted using the RNAi technique and pharmacological inhibition. Western blot, immunohistochemistry, and immunofluorescence examination were applied.
Results:
The protein presence of RIP1, but not RIP3, was increased in the mouse OA tissue and cultured chondrocytes exposed to TNF-α. Knockdown of RIP1 increased protein expression of collagen II and sex-determining region Y-box transcription factor 9, and reduced protein expression of matrix metallopeptidases 13 and a disintegrin and metalloproteinase with thrombospondin motifs 5. Inhibition of RIP1 reduced the phosphorylated NF-κB signals, decreased cell apoptosis, and restored extracellular matrix expression in cultured chondrocytes. Both RNAi and pharmacological inhibition of RIP1 decelerated the progress of OA in mice.
Conclusion:
RIP1 regulates chondrocyte apoptosis through NF-κB signaling. Inhibition of RIP1 provides a novel therapeutic approach for OA therapy.
Insights
Receptor-interacting serine/threonine kinase 1 (RIPK1) inhibition reduces chondrocyte apoptosis and osteoarthritis progression by regulating NF-κB signaling. This offers a potential new therapy for osteoarthritis.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Excessive chondrocyte death is a key factor in osteoarthritis (OA) pathogenesis.
- Receptor-interacting serine/threonine kinase 1 (RIPK1)-mediated signaling in programmed cell death is implicated in OA.
Purpose of the Study:
- To investigate the role of RIPK1-mediated signaling in chondrocyte apoptosis within OA.
- To explore RIPK1 inhibition as a potential therapeutic strategy for OA.
Main Methods:
- Evaluated RIPK1 protein expression in mouse OA cartilage and TNF-α-stimulated chondrocytes.
- Assessed apoptosis, necroptosis, and extracellular matrix markers.
- Utilized RNAi and pharmacological inhibitors targeting RIPK1.
- Employed Western blot, immunohistochemistry, and immunofluorescence.
Main Results:
- RIPK1 protein levels were elevated in OA cartilage and TNF-α-treated chondrocytes.
- RIPK1 inhibition upregulated collagen II and SOX9, while downregulating MMP13 and ADAMTS5.
- RIPK1 inhibition decreased NF-κB signaling, reduced chondrocyte apoptosis, and restored extracellular matrix.
- Both RNAi and pharmacological RIPK1 inhibition ameliorated OA progression in mice.
Conclusions:
- RIPK1 signaling regulates chondrocyte apoptosis via the NF-κB pathway.
- Inhibiting RIPK1 presents a promising therapeutic avenue for osteoarthritis treatment.
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