Matrix vesicle plasma cell membrane glycoprotein-1 regulates mineralization by murine osteoblastic MC3T3 cells.

Abstract

A naturally occurring nonsense truncation mutation of the inorganic pyrophosphate (PPi)-generating nucleoside triphosphate pyrophosphohydrolase (NTPPPH) PC-1 is associated with spinal and periarticular ligament hyperostosis and cartilage calcification in "tiptoe walking" (ttw) mice. Thus, we tested the hypothesis that PC-1 acts directly in the extracellular matrix to restrain mineralization. Cultured osteoblastic MC3T3 cells expressed PC-1 mRNA and produced hydroxyapatite deposits at 12-14 days. NTPPPH activity increased steadily over 14 days. Transforming growth factor-beta and 1,25-dihydroxyvitamin D3 increased PC-1 and NTPPPH in matrix vesicles (MVs). Because PC-1/NTPPPH was regulated in mineralizing MC3T3 cells, we stably transfected or infected cells with recombinant adenovirus, in order to express 2- to 6-fold more PC-1. PC-1/NTPPPH and PPi content increased severalfold in MVs derived from cells transfected with PC-1. Furthermore, MC3T3 cells transfected with PC-1 deposited approximately 80-90% less hydroxyapatite (by weight) than cells transfected with empty plasmid or enzymatically inactive PC-1. ATP-dependent 45Ca precipitation by MVs from cells overexpressing active PC-1 was comparably diminished. Thus, regulation of PC-1 controls the PPi content and function of osteoblast-derived MVs and matrix hydroxyapatite deposition. PC-1 may provide a novel therapeutic target in certain disorders of bone mineralization.

• Authors: K Johnson, A Moffa, Y Chen, K Pritzker, J Goding, R Terkeltaub
• Journal: Journal of bone and mineral research : the official journal of the American Society for Bone and Mineral Research (J Bone Miner Res) Vol. 14 Issue 6 Pg. 883-92 (Jun 1999) ISSN: 0884-0431 [Print] United States
• PMID: 10352096 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S., Research Support, U.S. Gov't, P.H.S.)

Chemical References

• Extracellular Matrix Proteins
• Liposomes
• Membrane Glycoproteins
• Durapatite
• Phosphoric Diester Hydrolases
• ectonucleotide pyrophosphatase phosphodiesterase 1
• Pyrophosphatases

Topics

• Adenoviridae (genetics)
• Animals
• Bone Density (physiology)
• Cell Differentiation (physiology)
• Cell Line
• Durapatite (metabolism)
• Extracellular Matrix Proteins (physiology)
• Gene Transfer Techniques
• Liposomes
• Membrane Glycoproteins (physiology)
• Mice
• Osteoblasts (physiology)
• Phosphoric Diester Hydrolases
• Pyrophosphatases