Calcium signaling leads to mitochondrial depolarization in impact-induced chondrocyte death in equine articular cartilage explants
| Autor: | M.E. Davies, Camille Huser |
|---|---|
| Rok vydání: | 2007 |
| Předmět: |
Cartilage
Articular medicine.medical_specialty Immunology chemistry.chemical_element Mitochondrion Calcium Weight Gain Chondrocyte Cathepsin B Weight-Bearing Organ Culture Techniques Rheumatology Reference Values Internal medicine medicine Animals Immunology and Allergy Pharmacology (medical) Calcium Signaling Horses Calcium signaling biology Ryanodine receptor Weight change Depolarization Calpain Dipeptides Mitochondria medicine.anatomical_structure Endocrinology chemistry biology.protein |
| Zdroj: | Arthritis & Rheumatism. 56:2322-2334 |
| ISSN: | 1529-0131 0004-3591 |
| DOI: | 10.1002/art.22717 |
| Popis: | Objective Chondrocyte apoptosis is an important factor in the progression of osteoarthritis. This study aimed to elucidate the mechanisms involved upstream of caspase 9 activation and, in particular, calcium signaling and mitochondrial depolarization. Methods Articular cartilage explants obtained from healthy horses were subjected to a single impact load (500-gm weight dropped from a height of 50 mm) and cultured in vitro for up to 48 hours. Chondrocyte death was quantified by the TUNEL method. Release of proteoglycans was determined by the dimethylmethylene blue assay. Weight change was measured, and mitochondrial depolarization was determined using JC-1 staining. To assess the role of calcium signaling in impact-induced chondrocyte death, explants were preincubated in culture medium containing various concentrations of calcium. Inhibitors were used to assess the role of individual signaling components in impact-induced chondrocyte death. Results Calcium quenching, inhibitors of calpains, calcium/calmodulin-regulated kinase II (CaMKII), and mitochondrial depolarization reduced impact-induced chondrocyte death after 48 hours in culture. Transient mitochondrial depolarization was observed 3–6 hours following a single impact load. Mitochondrial depolarization was prevented by calcium quenching, inhibitors of calpain, CaMKII, permeability transition pore formation, ryanodine receptor, and the mitochondrial uniport transporter. Cathepsin B did not appear to be involved in impact-induced chondrocyte death. The calpain inhibitor prevented proteoglycan loss, but the percentage weight gain and proteoglycan loss were unaffected by all treatments used. Conclusion Following a single impact load, calcium is released from the endoplasmic reticulum via the ryanodine receptor and is taken up by the mitochondria via the uniport transporter, causing mitochondrial depolarization and caspase 9 activation. In addition, calpains and CaMKII play important roles in causing mitochondrial depolarization. |
| Databáze: | OpenAIRE |
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