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Updated: May 28, 2026
Studies of Chaperone-Cochaperone Interactions using Homogenous Bead-Based Assay
Published on: July 21, 2021
Hsp90β inhibition modulates nitric oxide production and nitric oxide-induced apoptosis in human chondrocytes
Valentina Calamia1, Maria C de Andrés, Natividad Oreiro
1Rheumatology Division, ProteoRed/ISCIII Proteomic Group, INIBIC - Hospital Universitario A Coruña, As Xubias S/N, 15006 - A Coruña, Spain.
Background:
Hsp90β is a member of the Hsp90 family of protein chaperones. This family plays essential roles in the folding, maturation and activity of many proteins that are involved in signal transduction and transcriptional regulation. The role of this protein in chondrocytes is not well understood, although its increase in osteoarthritic cells has been reported. The present study aimed to explore the role of Hsp90β in key aspects of OA pathogenesis.
Methods:
Human OA chondrocytes were isolated from cartilage obtained from patients undergoing joint replacement surgery, and primary cultured. Cells were stimulated with proinflammatory cytokines (IL-1β or TNF-α) and nitric oxide donors (NOC-12 or SNP). For Hsp90β inhibition, two different chemical inhibitors (Geldanamycin and Novobiocin) were employed, or siRNA transfection procedures were carried out. Gene expression was determined by real-time PCR, apoptosis was quantified by flow cytometry and ELISA, and nitric oxide (NO) production was evaluated by the Griess method. Indirect immunofluorescence assays were performed to evaluate the presence of Hsp90β in stimulated cells.
Results:
Hsp90β was found to be increased by proinflammatory cytokines. Inhibition of Hsp90β by the chemicals Geldanamycin (GA) and Novobiocin (NB) caused a dose-dependent decrease of the NO production induced by IL-1β in chondrocytes, up to basal levels. Immunofluorescence analyses demonstrate that the NO donors NOC-12 and SNP also increased Hsp90β. Chemical inhibition or specific gene silencing of this chaperone reduced the DNA condensation and fragmentation, typical of death by apoptosis, that is induced by NO donors in chondrocytes.
Conclusions:
The present results show how Hsp90β modulates NO production and NO-mediated cellular death in human OA chondrocytes.
Insights
Heat shock protein 90 beta (Hsp90β) influences nitric oxide (NO) production and NO-mediated cell death in osteoarthritis (OA) chondrocytes. Inhibiting Hsp90β reduces NO levels and apoptosis in OA cells.
Area of Science:
- Molecular Biology
- Cell Biology
- Biochemistry
Background:
- Heat shock protein 90 beta (Hsp90β) is a chaperone protein involved in cellular signaling.
- Its role in chondrocytes and osteoarthritis (OA) pathogenesis is not fully understood.
- Hsp90β levels are elevated in osteoarthritic cells.
Purpose of the Study:
- To investigate the role of Hsp90β in key aspects of OA pathogenesis.
- To explore Hsp90β's modulation of nitric oxide (NO) production.
- To determine Hsp90β's involvement in NO-mediated chondrocyte apoptosis.
Main Methods:
- Human OA chondrocytes were isolated and cultured.
- Cells were stimulated with pro-inflammatory cytokines and NO donors.
- Hsp90β was inhibited using chemical inhibitors (Geldanamycin, Novobiocin) or siRNA.
- Gene expression, apoptosis, and NO production were quantified.
Main Results:
- Pro-inflammatory cytokines increased Hsp90β expression in chondrocytes.
- Hsp90β inhibition dose-dependently decreased IL-1β-induced NO production.
- NO donors also increased Hsp90β levels.
- Inhibition or silencing of Hsp90β reduced NO-induced apoptosis in chondrocytes.
Conclusions:
- Hsp90β plays a significant role in modulating NO production in OA chondrocytes.
- Hsp90β is involved in NO-mediated cellular death pathways in OA chondrocytes.
- Targeting Hsp90β may offer a therapeutic strategy for OA.
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