{"type": "root", "children": [{"type": "p", "children": [{"type": "t", "text": "\n Cartilage oligomeric matrix protein (COMP) is a large, pentameric, non‐collagenous extracellular matrix protein that belongs to the thrombospondin family and is predominantly expressed in cartilage. COMP plays multifaceted roles in extracellular matrix organization by interacting with other matrix constituents such as collagens and matrilins to facilitate collagen fibrillogenesis and proper matrix assembly."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "1"}]}, {"type": "t", "text": " In addition, COMP mediates cell–matrix interactions; its ability to support chondrocyte attachment is modulated by its conformation and involves binding to integrin receptors (e.g., α5β1 and αVβ3), thereby influencing cell adhesion and proliferation."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "3"}]}, {"type": "t", "text": " Moreover, COMP directly associates with growth factors – for instance, binding to the granulin–epithelin precursor (GEP) enhances chondrocyte proliferation and may be critical for matrix remodeling."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "5"}]}, {"type": "t", "text": "\n "}]}, {"type": "t", "text": "\n "}, {"type": "p", "children": [{"type": "t", "text": "\n Mutations in the COMP gene are causative for skeletal dysplasias such as pseudoachondroplasia and multiple epiphyseal dysplasia, underscoring its essential role in cartilage development; yet, animal studies suggest that the absence of COMP can be partially compensated by other matrix proteins."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "6"}]}, {"type": "t", "text": " In clinical settings, aberrant COMP expression and increased serum COMP levels are emerging as sensitive biomarkers for cartilage degradation in osteoarthritis and joint injury, reflecting altered cartilage matrix turnover."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "7"}]}, {"type": "t", "text": " Furthermore, proteolytic degradation of COMP by metalloproteinases such as ADAMTS-7 and ADAMTS-12 contributes to cartilage matrix breakdown observed in arthritic conditions."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "9"}]}, {"type": "t", "text": " Finally, dysregulated COMP expression is not limited to skeletal disorders but may also have broader clinical implications in fibrosis and tumor progression, where it is associated with altered extracellular matrix dynamics."}, {"type": "fg", "children": [{"type": "fg_f", "ref": "11"}]}, {"type": "t", "text": "\n "}]}, {"type": "rg", "children": [{"type": "r", "ref": 1, "children": [{"type": "t", "text": "Karen L Posey, Francoise Coustry, Jacqueline T Hecht "}, {"type": "b", "children": [{"type": "t", "text": "Cartilage oligomeric matrix protein: COMPopathies and beyond."}]}, {"type": "t", "text": " "}, {"type": "i", "children": [{"type": "t", "text": "Matrix Biol (2018)"}]}, {"type": "t", "text": " DOI: "}, {"type": "a", "children": [{"type": "t", "text": "10.1016/j.matbio.2018.02.023"}], "href": "https://doi.org/10.1016/j.matbio.2018.02.023"}, {"type": "t", "text": " PMID: "}, {"type": "a", "children": [{"type": "t", "text": "29530484"}], "href": "https://pubmed.ncbi.nlm.nih.gov/29530484"}]}, {"type": "r", "ref": 2, "children": [{"type": "t", "text": "Jacqueline T Hecht, Elizabeth Hayes, Richard Haynes, et al. 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