BioScience Trends. 2013;7(3):144-151. (DOI: 10.5582/bst.2013.v7.3.144)
Label-free quantification proteomics reveals novel calcium binding proteins in matrix vesicles isolated from mineralizing Saos-2 cells.
Zhou XY, Cui YZ, Luan J, Zhou XY, Zhang GL, Zhang XM, Han JX
Matrix vesicles (MVs) involved in the initiation of mineralization by deposition of hydroxyapatite (HA) in their lumen are released by the budding of mineralization-competent cells during skeletogenesis and bone development. To identify additional mineralization-related proteins, MVs were isolated from non-stimulated and stimulated Saos-2 cells in culture via an ExoquickTM approach and the corresponding proteomes were identified and quantified with label-free quantitative proteome technology. The isolated MVs were confirmed by electron microscopy, alkaline phosphatase activity (ALP), biomarkers, and mineral formation analyses. Label-free quantitative proteome analysis revealed that 19 calcium binding proteins (CaBPs), including Grp94, calnexin, calreticulin, calmodulin, and S100A4/A10, were up-regulated in MVs of Saos-2 cells upon stimulation of mineralization. This result provides new clues to study the mechanism of the initiation of MV-mediated mineralization.