title: Cyclical strain modulates metalloprotease and matrix gene expression in human tenocytes via activation of TGFβ.
abstract: Tendinopathies are a range of diseases characterised by degeneration and chronic tendon pain and represent a significant cause of morbidity. Relatively little is known about the underlying mechanisms; however onset is often associated with physical activity. A number of molecular changes have been documented in tendinopathy such as a decrease in overall collagen content, increased extracellular matrix turnover and protease activity. Metalloproteinases are involved in the homeostasis of the extracellular matrix and expression is regulated by mechanical strain. The aims of this study were to determine the effects of strain upon matrix turnover by measuring metalloproteinase and matrix gene expression and to elucidate the mechanism of action. Primary Human Achilles tenocytes were seeded in type I rat tail collagen gels in a Flexcell™ tissue train system and subjected to 5% cyclic uniaxial strain at 1Hz for 48h. TGFβ1 and TGFβRI inhibitor were added to selected cultures. RNA was measured using qRT-PCR and TGFβ protein levels were determined using a cell based luciferase assay. We observed that mechanical strain regulated the mRNA levels of multiple protease and matrix genes anabolically, and this regulation mirrored that seen with TGFβ stimulation alone. We have also demonstrated that the inhibition of the TGFβ signalling pathway abrogated the strain induced changes in mRNA and that TGFβ activation, rather than gene expression, was increased with mechanical strain. We concluded that TGFβ activation plays an important role in mechanotransduction. Targeting this pathway may have its place in the treatment of tendinopathy.
authors.affiliation: Soft Tissue Research Group, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK. Electronic address: Eleanor.R.Jones@uea.ac.uk.
authors.forename: Eleanor R
authors.initials: ER
authors.lastname: Jones
authors.affiliation: Soft Tissue Research Group, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: Gavin C
authors.initials: GC
authors.lastname: Jones
authors.affiliation: Soft Tissue Research Group, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Legerlotz
authors.affiliation: Soft Tissue Research Group, School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, UK.
authors.forename: Graham P
authors.initials: GP
authors.lastname: Riley
mesh_terms: D000818:Animals; D016326:Extracellular Matrix Proteins / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D045726:Metalloproteases / Q000235:genetics* / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D000077293:Receptor, Transforming Growth Factor-beta Type I; D018125:Receptors, Transforming Growth Factor beta / Q000037:antagonists & inhibitors / Q000378:metabolism; D013314:Stress, Mechanical; D013710:Tendons / Q000166:cytology* / Q000201:enzymology*; D016212:Transforming Growth Factor beta / Q000235:genetics / Q000378:metabolism*
chemical_list: D016326:Extracellular Matrix Proteins; D012333:RNA, Messenger; D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D017346:Protein Serine-Threonine Kinases; D000077293:Receptor, Transforming Growth Factor-beta Type I; C000625843:Tgfbr1 protein, rat; D045726:Metalloproteases
keywords: Mechanotransduction; Metalloproteinase; Strain; Tendon; Transforming Growth Factor β