Abstract |
Deficiency of PRG4 ( lubricin), the boundary lubricant in mammalian joints, contributes to increased joint friction accompanied by superficial and upper intermediate zone chondrocyte caspase-3 activation, as shown in lubricin-null (Prg4-/-) mice. Caspase-3 activity appears to be reversible upon the restitution of Prg4 either endogenously in vivo, in a gene trap mouse, or as an applied lubricant in vitro. In this study we show that intra-articular injection of human PRG4 in vivo in Prg4-/- mice prevented caspase-3 activation in superficial zone chondrocytes and was associated with a modest decrease in whole joint friction measured ex vivo using a joint pendulum method. Non-lubricated Prg4-/- mouse cartilage shows caspase cascade activation caused by mitochondrial dysregulation, and significantly higher levels of peroxynitrite (ONOO- and - OH) and superoxide (O-₂) compared to Prg4+/+ and Prg4+/- cartilage. Enzymatic activity levels of caspase 8 across Prg4 mutant mice were not significantly different, indicating no extrinsic apoptosis pathway activation. Western blots showed caspase-3 and 9 activation in Prg4-/- tissue extracts, and the appearance of nitrosylated Cys163 in the active cleft of caspase-3 which inhibits its enzymatic activity. These findings are relevant to patients at risk for arthrosis, from camptodactyl- arthropathy- coxa vara- pericarditis (CACP) syndrome and transient lubricin insufficiency due to trauma and inflammation.
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Authors | Kimberly A Waller, Ling X Zhang, Gregory D Jay |
Journal | International journal of molecular sciences
(Int J Mol Sci)
Vol. 18
Issue 6
(Jun 11 2017)
ISSN: 1422-0067 [Electronic] Switzerland |
PMID | 28604608
(Publication Type: Journal Article)
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Chemical References |
- PRG4 protein, human
- Prg4 protein, mouse
- Proteoglycans
- Casp3 protein, mouse
- Casp9 protein, mouse
- Caspase 3
- Caspase 9
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Topics |
- Animals
- Apoptosis
- Caspase 3
(metabolism)
- Caspase 9
(metabolism)
- Chondrocytes
(drug effects, metabolism, pathology)
- Disease Models, Animal
- Friction
- Injections, Intra-Articular
- Joint Diseases
(metabolism, pathology)
- Joints
(drug effects, metabolism, pathology)
- Mice
- Mice, Knockout
- Mitochondria
(drug effects, metabolism, pathology)
- Proteoglycans
(administration & dosage, genetics, pharmacology)
- Signal Transduction
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