Among the complex network of cytokines that influence odontoblast function during development and repair, TGF-beta1 is unique in its dual abilities to function as a potent immunosuppressant and as an inducer of extracellular matrix (ECM) production. The molecular mechanisms of TGF-beta1 action during dentin formation are poorly understood. To better understand the precise physiologic functions of TGF-beta1 in dentinogenesis we have studied mice with a loss-of-function mutation at the TGF-beta1 locus. TGF-beta 1(-/-) mice die at weaning from widespread inflammation due to the loss of a critical regulator of immune function. Our studies of adult denition in TGF-beta1 (-/-) mice kept alive on dexamethasone show extensive pulp and periapical pathology and a marked attrition of occlusal surfaces. Teeth of TGF-beta1(-/-) mice backcrossed onto immunodeficient backgrounds also showed significant changes in dentin likely caused by defects in mineralization. The impairment in dentinogenesis is thus linked directly to the loss of TGF-beta1 rather than to the secondary effects of inflammation. In the proposed studies, TGF-beta-1(-/-) athymic nude mice will be used to rigorously test the hypothesis that TGF-beta1 is important for odontoblast function during primary and reparative dentin formation.
In Aim 1, the structure and integrity of primary dentin will be assessed in TGF-beta1(-/-) nude mice by tetracycline labeling, Fourier transform infrared spectroscopy, ultrastructural and biomechanical approaches.
Aim 2 will use cellular and molecular approaches to assess whether the absence of TGF-beta1 affects the expression of alkaline phosphatase and key dentin ECM genes, using in situ hybridization, RT-PCR and immunolocalization analyses. The biosynthetic abilities of odontoblasts will be tested by labeling organ cultures with 3H-proline and 45Ca.
In Aim 3, the genetic pathways involving TGF-beta1 will be explored. The expression and functional relationship of genes like Bmp2 and Msx2 that may potentially interact with TGF-beta1 will be assessed in TGF-beta1(-/-) nude and Msx2(-/-) mice whose teeth also appear poorly mineralized. Studies in Aim 4 will assess whether TGF-beta1(-/-) odontoblasts can form reparative dentin in vivo. The effects of exogeneous TGF-beta1 placed at sites of pulp exposure will be compared in TGF-beta1(-/-) vs. TGF-beta1(+/-) nude littermates. The overall goal of these studies is to provide definitive information on TGF-beta1's role in dentin formation. Such insights will contribute to the development of bioactive dental materials to treat and prevent injuries of the dentin-pulp complex.
| Ogawa, Takuya; Kapadia, Hitesh; Wang, Bailiang et al. (2005) Studies on Pax9-Msx1 protein interactions. Arch Oral Biol 50:141-5 |
| Bronckers, Antonius L J J; Sasaguri, Kenichi; Cavender, Adriana C et al. (2005) Expression of Runx2/Cbfa1/Pebp2alphaA during angiogenesis in postnatal rodent and fetal human orofacial tissues. J Bone Miner Res 20:428-37 |
| Aberg, Thomas; Cavender, Adriana; Gaikwad, Joel S et al. (2004) Phenotypic changes in dentition of Runx2 homozygote-null mutant mice. J Histochem Cytochem 52:131-9 |
| Mensah, John K; Ogawa, Takuya; Kapadia, Hitesh et al. (2004) Functional analysis of a mutation in PAX9 associated with familial tooth agenesis in humans. J Biol Chem 279:5924-33 |
| Zou, S J; D'Souza, R N; Ahlberg, T et al. (2003) Tooth eruption and cementum formation in the Runx2/Cbfa1 heterozygous mouse. Arch Oral Biol 48:673-7 |
| Wise, G E; Frazier-Bowers, S; D'Souza, R N (2002) Cellular, molecular, and genetic determinants of tooth eruption. Crit Rev Oral Biol Med 13:323-34 |
| Hoffmann, Matthias; Gaikwad, Joel; Schmalz, Gottfried et al. (2002) Analysis of odontoblast gene expression using a novel approach, laser capture microdissection. Connect Tissue Res 43:376-80 |
| Hoffmann, M; Olson, K; Cavender, A et al. (2001) Gene expression in a pure population of odontoblasts isolated by laser-capture microdissection. J Dent Res 80:1963-7 |
| Gaikwad, J S; Hoffmann, M; Cavender, A et al. (2001) Molecular insights into the lineage-specific determination of odontoblasts: the role of Cbfa1. Adv Dent Res 15:19-24 |
| Stockton, D W; Das, P; Goldenberg, M et al. (2000) Mutation of PAX9 is associated with oligodontia. Nat Genet 24:18-9 |
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