Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
Review
. 2010 Mar;43(3):234-41.
doi: 10.1590/s0100-879x2010007500008.

Proteoliposomes as matrix vesicles' biomimetics to study the initiation of skeletal mineralization

A M S Simão  1 , M C Yadav, P Ciancaglini, J L Millán
Affiliations
Review

Proteoliposomes as matrix vesicles' biomimetics to study the initiation of skeletal mineralization

A M S Simão et al. Braz J Med Biol Res. 2010 Mar.

Abstract

During the process of endochondral bone formation, chondrocytes and osteoblasts mineralize their extracellular matrix by promoting the formation of hydroxyapatite (HA) seed crystals in the sheltered interior of membrane-limited matrix vesicles (MVs). Ion transporters control the availability of phosphate and calcium needed for HA deposition. The lipidic microenvironment in which MV-associated enzymes and transporters function plays a crucial physiological role and must be taken into account when attempting to elucidate their interplay during the initiation of biomineralization. In this short mini-review, we discuss the potential use of proteoliposome systems as chondrocyte- and osteoblast-derived MVs biomimetics, as a means of reconstituting a phospholipid microenvironment in a manner that recapitulates the native functional MV microenvironment. Such a system can be used to elucidate the interplay of MV enzymes during catalysis of biomineralization substrates and in modulating in vitro calcification. As such, the enzymatic defects associated with disease-causing mutations in MV enzymes could be studied in an artificial vesicular environment that better mimics their in vivo biological milieu. These artificial systems could also be used for the screening of small molecule compounds able to modulate the activity of MV enzymes for potential therapeutic uses. Such a nanovesicular system could also prove useful for the repair/treatment of craniofacial and other skeletal defects and to facilitate the mineralization of titanium-based tooth implants.

PubMed Disclaimer

Figures

Figure 1
Figure 1
Schematic representation of the molecules involved in matrix vesicle (MV)-mediated calcification including the most favored enzymatic reactions of their putative physiological substrates. This is a modified figure based on the one published in Ciancaglini et al. (54). Hydroxyapatite seed crystals are formed in the sheltered interior of MVs favored by the inorganic phosphate (Pi)-generating ability of PHOSPHO1, which uses phosphocholine (Pcho) and phosphoethanolamine (PEA) as substrates, as well as by the function of Pi-transporters (PiT) and annexins that mediate Ca2+ ion influx. Tissue-nonspecific alkaline phosphatase (TNAP) has a major role both as a PPiase and as an ATPase/ADPase and thus participates in the calcification process by restricting the concentration of extracellular PPi while also contributing to the Pi pool available for calcification. PC-1/nucleotide pyrophosphatase phosphodiesterase 1 (NPP1) can act as a backup PPiase and also ATPase, particularly in the absence of TNAP. Thick lines indicate the most favored reactions, while dotted lines indicate alternative backup enzymatic reactions. Outside the MVs, collagen acts as a primary scaffold for the deposition of hydroxyapatite crystals.
Figure 2
Figure 2
Electron microscopy using negative staining of: A, Liposomes consisting of dipalmitoylphosphatidylcholine (DPPC) and B, tissue-nonspecific alkaline phosphatase reconstituted in DPPC liposomes, both with magnification of 50X. A 5-μL suspension of liposomes or proteoliposomes was placed on carbon-coated copper grids for 1 min to sediment the sample. The excess buffer was removed and exchanged for 2% (w/v) of an aqueous solution of uranyl-acetate for 15 s; excess uranyl-acetate was removed, grids were air-dried for 2–5 min and examined with a Hitachi H600A transmission electron microscope at 75 kV. Images were collected with an L9C cooled CCD, 11.2 megapixel camera (Special Achievement in innovation - SIA)
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

See all "Cited by" articles

References

    1. Glimcher MJ. Bone: nature of the calcium phosphate crystals and cellular, structural, and physical chemical mechanisms in their formation. Rev Mineral Geochem. 2006;64:223–282.
    1. Anderson HC, Garimella R, Tague SE. The role of matrix vesicles in growth plate development and biomineralization. Front Biosci. 2005;10:822–837. - PubMed
    1. Giachelli CM. Inducers and inhibitors of biomineralization: lessons from pathological calcification. Orthod Craniofac Res. 2005;8:229–231. - PubMed
    1. Wu LN, Genge BR, Kang MW, Arsenault AL, Wuthier RE. Changes in phospholipid extractability and composition accompany mineralization of chicken growth plate cartilage matrix vesicles. J Biol Chem. 2002;277:5126–5133. - PubMed
    1. Terkeltaub RA. Inorganic pyrophosphate generation and disposition in pathophysiology. Am J Physiol Cell Physiol. 2001;281:C1–C11. - PubMed