1. Hypoxia Inducible Factor-1α Is a Regulator of Autophagy in Osteoarthritic Chondrocytes
- Author
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Shunyi Lu, Chi Zhang, Junren Lu, Yi Peng, Tengfei Fu, Libo Jiang, Jiapeng Zou, Jiayi Wang, and Jian Zhang
- Subjects
Cartilage, Articular ,Autophagy ,Biomedical Engineering ,Regulator ,Physical Therapy, Sports Therapy and Rehabilitation ,Biology ,Hypoxia (medical) ,Cell Hypoxia ,Chondrocyte ,Cell biology ,Chondrocytes ,medicine.anatomical_structure ,Hypoxia-inducible factors ,Mitophagy ,medicine ,Humans ,Immunology and Allergy ,medicine.symptom ,Hypoxia ,Clinical Research papers - Abstract
Objective To investigate the relationship between hypoxia inducible factor-1α (HIF-1α) and the autophagic response in osteoarthritic chondrocytes (OA), under inflammatory insult as represented by in vitro OA model. Methods Human chondrocyte cell line C28/I2 was cultured in both normoxic and hypoxic conditions and treated with interleukin-1β (IL1β) to emulate OA inflammatory insult in vitro. Cellular HIF-1α expression was silenced using siRNA transfection and cellular autophagic (P62/LC3II) response and OA chondrocyte damage (COL2A1/MMP13) related proteins were examined using western blotting. Cellular mitophagic (BNIP3/PINK1/Parkin) and apoptotic (Caspase/Cleaved Caspase 3) were also evaluated to assess mitophagy-mediated cell death due to HIF-1α silencing. Results Chondrocyte basal autophagy levels were higher in a HIF-1α elevated environment and was more resistant to IL1β-induced inflammatory insult. Increase in autophagic proteins showed better chondrocyte repair, which resulted a lower level of reactive oxygen species production, and lesser damage to chondrocyte integrity. Silencing HIF-1α activates cellular PINK1/Parkin and BNIP3 mitophagic proteins, which leads to the activation of Caspase/Cleaved Caspase 3 apoptotic cascade. Conclusion Our results show that chondrocyte autophagy is dependent on HIF-1α expression, showing the importance of HIF-1α in hypoxic chondrocyte function in OA. Dysregulation of HIF-1α expression results in the activation of mitophagy-mediated apoptosis.
- Published
- 2021
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