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Multiple changes in gene expression in chronic human Achilles tendinopathy
Abstract:
Atlas cDNA cell interaction arrays (CLONTECH) were used to examine degenerate tissue from four patients with Achilles tendon disorders, in order to identify changes in expression of genes important in cell-cell and cell-matrix interactions. The greatest difference between normal (post-mortem) and degenerate tissue samples was in the level of MMP-3 (stromelysin) mRNA, which was down-regulated in all the degenerate samples. Quantitative RT-PCR assay of RNA extracted from paired 'normal' and degenerate Achilles tendon tissue samples taken from tendons during surgery mirrored the results of the arrays. Levels of MMP-3 mRNA were lower, whereas levels of type-I and type-III collagen mRNAs were significantly higher, in the degenerate compared to the 'normal' samples. Immunoblotting of proteins extracted from the same tendon samples showed that three of four normal tissue samples taken from individuals without apparent tendon disorder had much higher levels of MMP-3 protein than 'normal' or degenerate samples from patients with tendinosis. We suggest that MMP-3 may play an important role in the regulation of tendon extracellular matrix degradation and tissue remodelling.
Insights
Matrix metalloproteinase-3 (MMP-3) mRNA and protein levels are lower in degenerate Achilles tendon tissue. This suggests MMP-3 plays a key role in tendon extracellular matrix remodeling and degradation.
Area of Science:
- Biochemistry
- Molecular Biology
- Orthopedics
Background:
- Achilles tendon disorders involve changes in extracellular matrix.
- Cell-cell and cell-matrix interactions are crucial in tendon health.
Purpose of the Study:
- To identify gene expression changes in degenerate Achilles tendon tissue.
- To investigate the role of matrix metalloproteinase-3 (MMP-3) in tendon disorders.
Main Methods:
- Atlas cDNA cell interaction arrays were used to analyze gene expression.
- Quantitative RT-PCR confirmed mRNA levels.
- Immunoblotting assessed protein levels.
Main Results:
- MMP-3 mRNA was significantly down-regulated in degenerate Achilles tendon samples.
- Type-I and type-III collagen mRNAs were significantly higher in degenerate samples.
- MMP-3 protein levels were lower in degenerate and some normal tendon samples from patients with tendinosis.
Conclusions:
- MMP-3 down-regulation is associated with Achilles tendon degeneration.
- MMP-3 may regulate extracellular matrix degradation and tissue remodeling in tendons.
- Further research into MMP-3's role in tendon pathology is warranted.