Back to Search
Start Over
Long-chain polyphosphate in osteoblast matrix vesicles: Enrichment and inhibition of mineralization.
- Source :
-
Biochimica et biophysica acta. General subjects [Biochim Biophys Acta Gen Subj] 2019 Jan; Vol. 1863 (1), pp. 199-209. Date of Electronic Publication: 2018 Oct 10. - Publication Year :
- 2019
-
Abstract
- Background: Inorganic polyphosphate (polyP) is a fundamental and ubiquitous molecule in prokaryotes and eukaryotes. PolyP has been found in mammalian tissues with particularly high levels of long-chain polyP in bone and cartilage where critical questions remain as to its localization and function. Here, we investigated polyP presence and function in osteoblast-like SaOS-2 cells and cell-derived matrix vesicles (MVs), the initial sites of bone mineral formation.<br />Methods: PolyP was quantified by 4',6-diamidino-2-phenylindole (DAPI) fluorescence and characterized by enzymatic methods coupled to urea polyacrylamide gel electrophoresis. Transmission electron microscopy and confocal microscopy were used to investigate polyP localization. A chicken embryo cartilage model was used to investigate the effect of polyP on mineralization.<br />Results: PolyP increased in concentration as SaOS-2 cells matured and mineralized. Particularly high levels of polyP were observed in MVs. The average length of MV polyP was determined to be longer than 196 P <subscript>i</subscript> residues by gel chromatography. Electron micrographs of MVs, stained by two polyP-specific staining approaches, revealed polyP localization in the vicinity of the MV membrane. Additional extracellular polyP binds to MVs and inhibits MV-induced hydroxyapatite formation.<br />Conclusion: PolyP is highly enriched in matrix vesicles and can inhibit apatite formation. PolyP may be hydrolysed to phosphate for further mineralization in the extracellular matrix.<br />General Significance: PolyP is a unique yet underappreciated macromolecule which plays a critical role in extracellular mineralization in matrix vesicles.<br /> (Copyright © 2018 Elsevier B.V. All rights reserved.)
- Subjects :
- Alkaline Phosphatase metabolism
Animals
Bone and Bones metabolism
Calcification, Physiologic
Calcium chemistry
Cartilage metabolism
Cell Line, Tumor
Chick Embryo
Extracellular Matrix metabolism
Humans
Hydrolysis
Indoles chemistry
Light
Microscopy, Confocal
Microscopy, Electron, Transmission
Osteogenesis
Scattering, Radiation
Type C Phospholipases chemistry
Durapatite chemistry
Osteoblasts metabolism
Polyphosphates chemistry
Subjects
Details
- Language :
- English
- ISSN :
- 1872-8006
- Volume :
- 1863
- Issue :
- 1
- Database :
- MEDLINE
- Journal :
- Biochimica et biophysica acta. General subjects
- Publication Type :
- Academic Journal
- Accession number :
- 30312769
- Full Text :
- https://doi.org/10.1016/j.bbagen.2018.10.003