DSPP effects on in vivo bone mineralization

• Published in: Bone (New York, N.Y.) Vol. 43; no. 6; pp. 983 - 990
• Main Authors: Verdelis, Kostas, Ling, Yunfeng, Sreenath, Taduru, Haruyama, Naoto, MacDougall, Mary, van der Meulen, Marjolein C.H, Lukashova, Lyudmila, Spevak, Lyudmila, Kulkarni, Ashok B, Boskey, Adele L
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.12.2008; Elsevier
• Subjects: Animals; Biological and medical sciences; Bone; Bone Density; Calcification, Physiologic - physiology; Cell physiology; Dentin sialophosphoprotein; Diseases of the osteoarticular system; Extracellular Matrix Proteins; FTIR spectroscopic imaging; FTIRI; Fundamental and applied biological sciences. Psychology; Medical sciences; Mice; Mice, Knockout; Micro-computed tomography; Mineralization, calcification; Molecular and cellular biology; Orthopedics; Phosphoproteins; Protein Precursors - genetics; Protein Precursors - physiology; Sialoglycoproteins; Spectroscopy, Fourier Transform Infrared; Tomography, X-Ray Computed; Vertebrates: anatomy and physiology, studies on body, several organs or systems; Dentin sialophosphoprotein; FTIRI; Bone; Micro-computed tomography; FTIR spectroscopic imaging; Dentin; Radiodiagnosis; In vivo; Mineralization; Morphology; Orthopedics; Medical imagery; Computerized axial tomography
• ISSN: 8756-3282; 1873-2763
• DOI: 10.1016/j.bone.2008.08.110

Abstract Dentin sialophosphoprotein has been implicated in the mineralization process based on the defective dentin formation in Dspp null mice ( Dspp −/−). Dspp is expressed at low levels in bone and Dspp −/− femurs assessed by quantitative micro-computed tomography (micro-CT) and Fourier transform infrared spectroscopic imaging (FTIRI) exhibit some mineral and matrix property differences from wildtype femurs in both developing and mature mice. Compared to wildtype, Dspp −/− mice initially (5 weeks) and at 7 months had significantly higher trabecular bone volume fractions and lower trabecular separation, while at 9 months, bone volume fraction and trabecular number were lower. Cortical bone mineral density, area, and moments of inertia in Dspp −/− were reduced at 9 months. By FTIRI, Dspp −/− animals initially (5 months) contained more stoichiometric bone apatite with higher crystallinity (crystal size/perfection) and lower carbonate substitution. This difference progressively reversed with age (significantly decreased crystallinity and increased acid phosphate content in Dspp −/− cortical bone by 9 months of age). Mineral density as determined in 3D micro-CT and mineral-to-matrix ratios as determined by 2D FTIRI in individual cortical and trabecular bones were correlated ( r2 = 0.6, p < 0.04). From the matrix analysis, the collagen maturity of both cortical and trabecular bones was greater in Dspp −/− than controls at 5 weeks; by 9 months this difference in cross-linking pattern did not exist. Variations in mineral and matrix properties observed at different ages are attributable, in part, to the ability of the Dspp gene products to regulate both initial mineralization and remodeling, implying an effect of Dspp on bone turnover.