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Updated: May 22, 2025
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Micro-dissection of Enamel Organ from Mandibular Incisor of Rats Exposed to Environmental Toxicants
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Distinctive Amelogenesis Imperfecta in Loeys-Dietz Syndrome Type II
O Duverger1, S K Wang1, Q N Liu1
1Craniofacial Anomalies and Regeneration Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA.
Journal of Dental Research
|April 22, 2025
Summary
Loeys-Dietz syndrome (LDS2), caused by TGFBR2 mutations, leads to severe enamel defects due to disrupted ameloblast movement. This study characterized these defects in human teeth and a mouse model, revealing impaired biomechanics.
Area of Science:
- Genetics
- Developmental Biology
- Biomaterials Science
Background:
- Loeys-Dietz syndrome (LDS) involves mutations in the transforming growth factor-β (TGF-β) signaling pathway, causing aortic aneurysms and craniofacial issues.
- While various LDS mutations affect TGF-β pathway genes, severe enamel defects are specifically linked to mutations in the TGFBR2 gene (LDS2).
Purpose of the Study:
- To characterize enamel defects in LDS2 using human teeth and a mouse model.
- To investigate the underlying molecular mechanisms of enamel abnormalities in LDS2.
Main Methods:
- Analysis of deciduous teeth from LDS2 patients.
- Phenotypic characterization of enamel in a Tgfbr2-mutant mouse model.
- Molecular analysis of ameloblasts and enamel organ gene expression.
Main Results:
- LDS2 deciduous teeth showed impaired ultrastructure and biomechanical properties, with variable mineralization.
- Tgfbr2-mutant mice exhibited disrupted enamel rod decussation and impaired biomechanics, not altered mineralization or quantity.
- Molecular analysis indicated altered distribution/activation of NDRG1, Rac1/Cdc42, and Myosin II in ameloblasts, suggesting impaired cell movement.
Conclusions:
- TGFBR2 mutations in LDS2 cause unique enamel defects characterized by disrupted ameloblast coordination and impaired biomechanical properties.
- The mechanism involves altered cytoskeletal dynamics in ameloblasts, distinct from the broader TGF-β pathway effects seen in aortic tissues.
- Further research is needed to fully elucidate the precise molecular pathways linking TGFBR2 mutations to these specific enamel defects.
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