title: Integrin - dependent mechanotransduction in mechanically stimulated human annulus fibrosus cells: evidence for an alternative mechanotransduction pathway operating with degeneration.
abstract: Intervertebral disc (IVD) cells derived from degenerate tissue respond aberrantly to mechanical stimuli, potentially due to altered mechanotransduction pathways. Elucidation of the altered, or alternative, mechanotransduction pathways operating with degeneration could yield novel targets for the treatment of IVD disease. Our aim here was to investigate the involvement of RGD-recognising integrins and associated signalling molecules in the response to cyclic tensile strain (CTS) of human annulus fibrosus (AF) cells derived from non-degenerate and degenerate IVDs. AF cells from non-degenerate and degenerate human IVDs were cyclically strained with and without function blocking RGD - peptides with 10% strain, 1.0 Hz for 20 minutes using a Flexercell® strain device. QRT-PCR and Western blotting were performed to analyse gene expression of type I collagen and ADAMTS -4, and phosphorylation of focal adhesion kinase (FAK), respectively. The response to 1.0 Hz CTS differed between the two groups of AF cells, with decreased ADAMTS -4 gene expression and decreased type I collagen gene expression post load in AF cells derived from non-degenerate and degenerate IVDs, respectively. Pre-treatment of non-degenerate AF cells with RGD peptides prevented the CTS-induced decrease in ADAMTS -4 gene expression, but caused an increase in expression at 24 hours, a response not observed in degenerate AF cells where RGD pre-treatment failed to inhibit the mechano-response. In addition, FAK phosphorylation increased in CTS stimulated AF cells derived from non-degenerate, but not degenerate IVDs, with RGD pre-treatment inhibiting the CTS - dependent increase in phosphorylated FAK. Our findings suggest that RGD -integrins are involved in the 1.0 Hz CTS - induced mechano-response observed in AF cells derived from non-degenerate, but not degenerate IVDs. This data supports our previous work, suggesting an alternative mechanotransduction pathway may be operating in degenerate AF cells.
authors.affiliation: Centre for Regenerative Medicine, Institute of Inflammation and Repair, Faculty of Medical and Human Sciences, The University of Manchester, Manchester, United Kingdom.
authors.forename: Hamish T J
authors.initials: HT
authors.lastname: Gilbert
authors.forename: Navraj S
authors.initials: NS
authors.lastname: Nagra
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Freemont
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Millward-Sadler
authors.forename: Judith A
authors.initials: JA
authors.lastname: Hoyland
mesh_terms: D002470:Cell Survival; D002478:Cells, Cultured; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000378:metabolism; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D016023:Integrins / Q000378:metabolism*; D007403:Intervertebral Disc / Q000166:cytology*; D055959:Intervertebral Disc Degeneration / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D040542:Mechanotransduction, Cellular / Q000187:drug effects / Q000502:physiology*; D009842:Oligopeptides / Q000494:pharmacology; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction
chemical_list: D016023:Integrins; D009842:Oligopeptides; C047981:arginyl-glycyl-aspartic acid; D051416:Focal Adhesion Protein-Tyrosine Kinases
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