The extracellular matrix of newborn, 7- and 21-day-old fibromodulin-deficient (Fmod KO) mice was compared with age-matched wild-type (WT) mice. Western blotting of proteins from 21-day-old WT mice revealed that the molecular weight of Fmod is smaller in dental tissues (approx. 40 kDa) compared to alveolar bone extracts (approx. 52 kDa). Dentin matrix protein1 (DMP1) was slightly increased in Fmod KO versus WT tooth extracts. After chondroitinase ABC digestion, dentin sialophosphoprotein (DSPP) appeared as 2 strong bands (approx. 150 and 70 kDa) in incisors from 21-day-old Fmod KO mice, whereas the smaller-sized species of DSPP was nearly absent in WT molars and no difference was detected between WT and KO mice in molars. Dentin mineralization was altered in newborn and 7-day-old KO mice, but seemed normal in 21-day-old KO mice. DMP1 and DSPP may be involved in compensatory mechanisms. The enamel had a twisted appearance and looked porous at day 21 in KO incisor, and the outer aprismatic layer was missing in the molar. Alveolar bone formation was enhanced in Fmod KO mice at days 0 and 7, whereas no difference was detected at day 21. We conclude that Fmod may control dental tissue formation and early maturation, where it acts mostly as an inhibitor in alveolar bone accumulation, excerpting its effects only at early developing stages. These dual functions may be related to the different forms of Fmod found in bone versus teeth.

Keywords:
Fibromodulin, Dentinogenesis, Amelogenesis, Osteogenesis, Collagen fibrillation, Enamel, Alveolar bone, Mineralization
1.
Fisher, L.W., S.W. Whitson, L.V. Avioli, J.D. Termine (1983) Matrix sialoprotein of developing bone. J Biol Chem 258: 12723–12727.
2.
Fisher, L.W., N.S. Fedarko (2003) Six genes expressed in bones and teeth encode the current members of the SIBLING family of proteins. Connect Tissue Res 44: 33–40.
3.
Fisher, L.W., J.T.III Stubbs, M.F. Young (1995) Antisera and cDNA probes to human and certain animal model bone matrix noncollagenous proteins. Acta Orthop Scand 266: 61–65.
4.
Goldberg, M., D. Septier, A. Oldberg, M.F. Young, L.G. Ameye (2006) Fibromodulin-deficient mice display impaired collagen fibrillogenesis in predentin as well as altered dentin mineralization and enamel formation. J Histochem Cytochem 54: 525–537.
5.
Hall, R., D. Septier, G. Embery, M. Goldberg (1999) Stromelysin-1 (MMP-3) in forming enamel and predentine in rat incisor-coordinated distribution with proteoglycans suggests a functional role. Histochem J 31: 761–770.
6.
Iozzo, R.V. (1999) The biology of the small leucine-rich proteoglycans: functional network of interactive proteins. J Biol Chem 274: 18843–18846.
7.
Neame, P.J., C.J. Kay (2000) Small leucine-rich proteoglycans; in Iozzo, R.V. (ed): Proteoglycans: Structure, Biology, and Molecular Interations. New York, Marcel Dekker, pp 201–235.
8.
Oldberg, A., P. Antonsson, K. Lindblom, D. Heinegard (1989) A collagen-binding 59-kD protein (fibromodulin) is structurally related to the small interstitial proteoglycans PG-S1 and PG-S2 (decorin). EMBO J 8: 2601–2604.
9.
Roughley, P.J., R.J. White, G. Cs-Szabo, J.S. Mort (1996) Changes with age in the structure of fibromodulin in human articular cartilage. Osteoarthritis Cartilage 4: 153–161.
10.
Scott, J.E. (1996) Proteodermatan and proteokeratan sulfate (decorin, lumican/fibromodulin) proteins are horseshoe shaped. Implications for their interactions with collagen. Biochemistry 35: 8795–8799.
11.
Soo, C., F.Y. Hu, X. Zhang, Y. Wang, S.R. Beanes, H.P. Lorenz, M.H. Hedrick, R.J. Mackool, A. Plaas, S.J. Kim, M.T. Longaker, E. Freymiller, K. Ting (2000) Differential expression of fibromodulin, a transforming growth factor-beta modulator, in fetal skin development and scarless repair. Am J Pathol 157: 423–433.
12.
Tartaix, P.H., M. Doulaverakis, A. George, L.W. Fisher, W.T. Butler, C. Qin, E. Salih, M. Tan, Y. Fujimoto, L. Spevak, A.L. Boskey (2004) In vitro effects of dentin matrix protein-1 on hydroxyapatite formation provide insights into in vivo functions. J Biol Chem 279: 18115–18120.
13.
Wilda, M., D. Bachner, W. Just, C. Geerkens, P. Kraus, W. Vogel, H. Hameister (2000) A comparison of the expression pattern of five genes of the family of small leucine-rich proteoglycans during mouse development. J Bone Miner Res 15: 2187–2196.
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2008
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