title: Proteomic analysis reveals age-related changes in tendon matrix composition, with age- and injury-specific matrix fragmentation.
abstract: Energy storing tendons, such as the human Achilles and equine superficial digital flexor tendon (SDFT), are highly prone to injury, the incidence of which increases with aging. The cellular and molecular mechanisms that result in increased injury in aged tendons are not well established but are thought to result in altered matrix turnover. However, little attempt has been made to fully characterize the tendon proteome nor determine how the abundance of specific tendon proteins changes with aging and/or injury. The aim of this study was, therefore, to assess the protein profile of normal SDFTs from young and old horses using label-free relative quantification to identify differentially abundant proteins and peptide fragments between age groups. The protein profile of injured SDFTs from young and old horses was also assessed. The results demonstrate distinct proteomic profiles in young and old tendon, with alterations in the levels of proteins involved in matrix organization and regulation of cell tension. Furthermore, we identified several new peptide fragments (neopeptides) present in aged tendons, suggesting that there are age-specific cleavage patterns within the SDFT. Proteomic profile also differed between young and old injured tendon, with a greater number of neopeptides identified in young injured tendon. This study has increased the knowledge of molecular events associated with tendon aging and injury, suggesting that maintenance and repair of tendon tissue may be reduced in aged individuals and may help to explain why the risk of injury increases with aging.
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE.
authors: Mandy J
authors: MJ
authors: Peffers
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE, Institute of Bioengineering, Queen Mary University of London, Mile End Road, London E1 4NS, and c.thorpe@qmul.ac.uk.
authors: Chavaunne T
authors: CT
authors: Thorpe
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE.
authors: John A
authors: JA
authors: Collins
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE, School of Life Sciences, Ngee Ann Polytechnic, Singapore 599489.
authors: Robin
authors: R
authors: Eong
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE, School of Life Sciences, Ngee Ann Polytechnic, Singapore 599489.
authors: Timothy K J
authors: TK
authors: Wei
authors: Institute of Bioengineering, Queen Mary University of London, Mile End Road, London E1 4NS, and.
authors: Hazel R C
authors: HR
authors: Screen
authors: From the Department of Musculoskeletal Biology, Institute of Ageing and Chronic Disease, University of Liverpool, Leahurst Campus, Neston CH64 7TE.
authors: Peter D
authors: PD
authors: Clegg
mesh_terms: D000367:Age Factors; D000375:Aging / Q000235:genetics* / Q000473:pathology; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005109:Extracellular Matrix / Q000378:metabolism; D006736:Horses / Q000235:genetics* / Q000502:physiology; D006801:Humans; D040901:Proteomics; D013708:Tendon Injuries / Q000235:genetics* / Q000473:pathology; D013710:Tendons / Q000378:metabolism / Q000473:pathology
keywords: Aging; Collagen; Disease; Equine; Fibromodulin; Mass Spectrometry (MS); Neopeptide; Protein Degradation; Proteoglycan