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Updated: Dec 22, 2025
Software-Assisted Quantitative Measurement of Osteoarthritic Subchondral Bone Thickness
Published on: March 18, 2022
PHF23 negatively regulates the autophagy of chondrocytes in osteoarthritis
Talatibaike Maimaitijuma1, Jia-Hong Yu2, Ya-Li Ren3
1Orthopedic Department, Peking University First Hospital, Beijing, China.
Aim:
Osteoarthritis (OA) is the main cause of disability and joint replacement surgery in the elderly. As a crucial cell survival mechanism, autophagy has been reported to decrease in OA. PHF23 is a new autophagy inhibitor which was first reported by us previously. This study aimed to explore the anti-autophagic mechanism of PHF23 to make it a possible therapeutic target of OA.
Main Method:
Lentiviral vectors specific to PHF23 were used on chondrocytes (C28/I2) to establish PHF23 overexpressed or knockdown stable cell strains. Interleukin (IL)-1β (10 ng/mL) and chloroquine (CQ, 25 uM) were used as an inducer of OA and inhibitor of lysosome, respectively. Autophagy was evaluated by autophagosome formation using transmission electron microscopy (TEM) and western blot analysis of P62 and LC3B on different groups of cells. Effects of PHF23 on OA were evaluated by collagen II immunofluorescent staining and western blot analysis of OA-associated proteins MMP13 and ADAMTS5. Effects of PHF23 on AMPK and mTOR/S6K pathways and mitophagy were determined by western blot analysis.
Key Findings:
Knockdown of PHF23 enhanced IL-1β-induced autophagy, while overexpression of PHF23 exerted the opposite effect. Knockdown of PHF23 protected chondrocytes against IL-1β-induced OA by decreasing the levels of OA-associated proteins and increasing expression of Collagen II. Knockdown of PHF23 also increased mitophagy level and altered the phosphorylation levels of AMPK, mTOR, and S6K.
Significance:
PHF23 downregulates autophagy, mitophagy in IL-1β-induced OA-like chondrocytes and alters the activities of AMPK and mTOR/S6K, which suggests that PHF23 may be a possible therapeutic target for OA.
Insights
PHF23 inhibits autophagy and mitophagy in osteoarthritis (OA) chondrocytes, offering a potential therapeutic target. Reducing PHF23 levels protected against OA by modulating key cellular pathways.
Area of Science:
- Cell Biology
- Molecular Biology
- Biochemistry
Background:
- Osteoarthritis (OA) is a leading cause of disability in the elderly, often associated with decreased autophagy.
- PHF23, a novel autophagy inhibitor, presents a potential avenue for OA therapeutic development.
Purpose of the Study:
- To investigate the anti-autophagic mechanism of PHF23 in the context of osteoarthritis.
- To explore PHF23 as a potential therapeutic target for OA.
Main Methods:
- Chondrocytes (C28/I2) were manipulated using lentiviral vectors for PHF23 overexpression or knockdown.
- Osteoarthritis was induced using Interleukin (IL)-1β, and autophagy was assessed via autophagosome formation, P62, and LC3B.
- Collagen II, MMP13, ADAMTS5, mitophagy, AMPK, and mTOR/S6K pathways were analyzed using western blot and immunofluorescence.
Main Results:
- PHF23 knockdown enhanced IL-1β-induced autophagy, while overexpression inhibited it.
- Knockdown of PHF23 conferred chondroprotection against IL-1β by reducing OA markers and increasing Collagen II.
- PHF23 manipulation altered mitophagy and the phosphorylation status of AMPK, mTOR, and S6K pathways.
Conclusions:
- PHF23 downregulates autophagy and mitophagy in IL-1β-induced OA chondrocytes.
- PHF23 influences the AMPK and mTOR/S6K signaling pathways.
- These findings suggest PHF23 as a potential therapeutic target for osteoarthritis.
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