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The overexpression of SIRT1 inhibited osteoarthritic gene expression changes induced by interleukin-1β in human
Takehiko Matsushita1, Hiroshi Sasaki, Koji Takayama
1Department of Orthopaedic Surgery, Kobe University Graduate School of Medicine, 7-5-1 Kusunoki-cho, Chuo-ku, Kobe 650-0017, Japan. matsushi@med.kobe-u.ac.jp
Abstract:
In this study, we examined the effects of overexpression of SIRT1 on IL-1β-induced gene expression changes in human chondrocytes to explore a protective role of SIRT1 in human chondrocytes. SIRT1 was overexpressed in human chondrocytes by expression plasmid under stimulation with IL-1β. SIRT1 was also inhibited by siRNA under stimulation with IL-1β. Gene expression changes were examined by real-time PCR. The interaction of SIRT1 and p65 (NF-κB) were examined by Western blotting. SIRT1, MMP-13, and ADAMTS-5 expressions in human cartilage were examined by immunohistochemistry. IL-1β stimulation significantly up-regulated MMP-1, 2, 9, and 13 and ADAMTS-5. Overexpression of SIRT1 significantly inhibited the up-regulation of those genes caused by IL-1β while the inhibition of SIRT1 further increased them. In addition, the overexpression of SIRT1 markedly reduced the IL-1β-induced acetylation of p65. SIRT1 expression was clearly detected in the non-OA cartilage while MMP-13 and ADAMTS-5 were undetectable. In contrast, in the OA cartilage, SIRT1 expression was decreased while MMP-13 and ADAMTS-5 were increased. Our observations suggested that SIRT1 can play a protective role by suppressing IL-1β-induced expressions of cartilage-degrading enzymes partially through the modulation of the NF-κB pathway. SIRT1 overexpression might be a new therapeutic approach for OA.
Insights
Sirtuin 1 (SIRT1) protects human chondrocytes from interleukin-1 beta (IL-1β) induced damage by reducing cartilage-degrading enzymes. SIRT1 overexpression may offer a new therapeutic strategy for osteoarthritis (OA).
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Interleukin-1 beta (IL-1β) is a key mediator in cartilage degradation.
- Sirtuin 1 (SIRT1) is implicated in cellular protection and inflammation.
- Understanding SIRT1's role in chondrocytes is crucial for osteoarthritis (OA) research.
Purpose of the Study:
- To investigate the protective effects of SIRT1 overexpression in human chondrocytes against IL-1β stimulation.
- To elucidate the mechanism by which SIRT1 influences IL-1β-induced gene expression.
- To explore the potential of SIRT1 as a therapeutic target for OA.
Main Methods:
- Human chondrocytes were treated with IL-1β, and SIRT1 was overexpressed or inhibited using expression plasmids and siRNA.
- Gene expression of cartilage-degrading enzymes (MMPs, ADAMTS-5) was quantified using real-time PCR.
- Protein interactions and modifications were analyzed via Western blotting.
- Immunohistochemistry was used to assess SIRT1, MMP-13, and ADAMTS-5 expression in human cartilage tissues.
Main Results:
- IL-1β significantly upregulated MMPs and ADAMTS-5 in chondrocytes.
- SIRT1 overexpression suppressed IL-1β-induced upregulation of these enzymes, while SIRT1 inhibition exacerbated it.
- SIRT1 overexpression reduced IL-1β-induced p65 (NF-κB) acetylation.
- SIRT1 was decreased, while MMP-13 and ADAMTS-5 were increased in osteoarthritis cartilage compared to non-osteoarthritis cartilage.
Conclusions:
- SIRT1 plays a protective role in human chondrocytes by inhibiting IL-1β-induced expression of cartilage-degrading enzymes.
- Modulation of the NF-κB pathway is involved in SIRT1's protective mechanism.
- SIRT1 overexpression presents a potential novel therapeutic approach for osteoarthritis.
