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Mechanical loading regulates tenascin-C expression in the osteotendinous junction.
T A Järvinen1, L Jozsa, P Kannus
1Institute of Medical Technology and Medical School, University of Tampere, Tampere, Finland. blteja@uta.fi
Journal of Cell Science
|August 27, 1999
Summary
Mechanical stress significantly regulates tenascin-C (TN) expression in the bone-tendon junction. Immobilization reduced TN, while remobilization, especially intensified running, restored and even increased its levels.
Area of Science:
- Biochemistry
- Cell Biology
- Biomechanics
Background:
- Tenascin-C (TN) is an elastic extracellular matrix protein with restricted expression in normal tissues.
- TN is highly expressed during embryogenesis and hyperplastic processes, suggesting a role in tissue remodeling.
Purpose of the Study:
- To investigate the impact of mechanical stress on tenascin-C (TN) expression in vivo.
- To determine how different mechanical loading states affect TN expression at the bone-tendon attachment.
Main Methods:
- Immunohistochemical analysis of TN expression at the rat quadriceps muscle's osteotendinous junction (OTJ).
- Experimental groups included cast immobilization, free cage activity (remobilization), and intensified treadmill running (low- and high-intensity).
Main Results:
- TN was abundant in the normal OTJ but nearly absent after three weeks of immobilization.
- Eight weeks of free cage activity partially restored TN expression, but not to contralateral limb levels.
- Low- and high-intensity running restored or exceeded normal TN levels, with high expression around chondrocytes, fibroblasts, and collagen fibers.
Conclusions:
- Mechanical strain is a key regulator of tenascin-C (TN) expression in vivo.
- Mechanical stress influences TN expression in fibroblasts and chondrocytes at the OTJ.
- This finding is crucial for understanding TN's role in embryogenesis, tendon degeneration, wound healing, and bone formation.