title: Quantitative proteomics at different depths in human articular cartilage reveals unique patterns of protein distribution.
abstract: The articular cartilage of synovial joints ensures friction-free mobility and attenuates mechanical impact on the joint during movement. These functions are mediated by the complex network of extracellular molecules characteristic for articular cartilage. Zonal differences in the extracellular matrix (ECM) are well recognized. However, knowledge about the precise molecular composition in the different zones remains limited. In the present study, we investigated the distribution of ECM molecules along the surface-to-bone axis, using quantitative non-targeted as well as targeted proteomics.\ In a discovery approach, iTRAQ mass spectrometry was used to identify all extractable ECM proteins in the different layers of a human lateral tibial plateau full thickness cartilage sample. A targeted MRM mass spectrometry approach was then applied to verify these findings and to extend the analysis to four medial tibial plateau samples. In the lateral tibial plateau sample, the unique distribution patterns of 70 ECM proteins were identified, revealing groups of proteins with a preferential distribution to the superficial, intermediate or deep regions of articular cartilage. The detailed analysis of selected 29 proteins confirmed these findings and revealed similar distribution patterns in the four medial tibial plateau samples. The results of this study allow, for the first time, an overview of the zonal distribution of a broad range of cartilage ECM proteins and open up further investigations of the functional roles of matrix proteins in the different zones of articular cartilage in health and disease.
authors.affiliation: Department of Biology, University of Copenhagen, Biocenter, DK-2200 Copenhagen N, Denmark. Electronic address: catharina.muller@med.lu.se.
authors.forename: Catharina
authors.initials: C
authors.lastname: Müller
authors.affiliation: Department of Clinical Sciences Lund, Lund University, BMC-C12, 221 84 Lund, Sweden.
authors.forename: Areej
authors.initials: A
authors.lastname: Khabut
authors.affiliation: Department of Clinical Sciences and Services, The Royal Veterinary College, University of London, Hatfield, United Kingdom.
authors.forename: Jayesh
authors.initials: J
authors.lastname: Dudhia
authors.affiliation: Department of Pathology, University of Oslo and Oslo University Hospital, Rikshospitalet, Oslo, Norway.
authors.forename: Finn P
authors.initials: FP
authors.lastname: Reinholt
authors.affiliation: Department of Biology, University of Copenhagen, Biocenter, DK-2200 Copenhagen N, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Aspberg
authors.affiliation: Department of Clinical Sciences Lund, Lund University, BMC-C12, 221 84 Lund, Sweden.
authors.forename: Dick
authors.initials: D
authors.lastname: Heinegård
authors.affiliation: Department of Clinical Sciences Lund, Lund University, BMC-C12, 221 84 Lund, Sweden. Electronic address: patrik.onnerfjord@med.lu.se.
authors.forename: Patrik
authors.initials: P
authors.lastname: Önnerfjord
mesh_terms: D002358:Cartilage, Articular / Q000378:metabolism*; D005109:Extracellular Matrix / Q000737:chemistry*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D013058:Mass Spectrometry; D064235:Matrilin Proteins / Q000302:isolation & purification*; D040901:Proteomics / Q000379:methods*; D019063:Tenascin / Q000378:metabolism
chemical_list: C439889:ASPN protein, human; D016326:Extracellular Matrix Proteins; D064235:Matrilin Proteins; D019063:Tenascin
keywords: Articular cartilage; Cartilage biology; Extracellular matrix proteins; Multiple reaction monitoring; Proteoglycan; Proteomics