title: Amelogenin- and enamelysin (Mmp-20)-deficient mice display altered birefringence in the secretory-stage enamel organic extracellular matrix.
abstract: Dental enamel is the most mineralized tissue of vertebrate organisms. Enamel biosynthesis is initiated by the secretion, processing, and self-assembly of a complex mixture of proteins. The formation of an ordered enamel organic extracellular matrix (ECM) seems be a crucial step for the proper formation of mineral phase. Polarizing microscopy demonstrates that the ordered supramolecular structure of the secretory-stage enamel organic ECM is strongly birefringent. In the present work we analyzed the birefringence of secretory-stage enamel organic ECM in amelogenin (Amelx)- and enamelysin (Mmp20)-deficient mice. Female Amelx+/- animals showed significant reduction in optical retardation values when compared with the Amelx+/+ subgroup (p=0.0029). The secretory-stage enamel organic ECM of the Amelx-/- subgroup did not exhibit birefringence. The secretory-stage enamel organic ECM of Mmp20-/- mice showed a significant decrease in optical retardation as compared with Mmp20+/+ and Mmp20+/- mice (p=0.0000). Mmp20+/- and Mmp20+/+ mice exhibited similar birefringence (p=1.0000). The results presented here support growing evidence for the idea that the birefringence of secretory-stage enamel organic ECM is influenced by the ordered supramolecular organization of its components.
authors: Department of Morphology, Piracicaba Dental School, State University of Campinas, Piracicaba, SP, Brazil.
authors: Alexandre R
authors: AR
authors: Espírito Santo
authors: John D
authors: JD
authors: Bartlett
authors: Carolyn W
authors: CW
authors: Gibson
authors: Yong
authors: Y
authors: Li
authors: Ashok B
authors: AB
authors: Kulkarni
authors: Sérgio R P
authors: SR
authors: Line
mesh_terms: D053523:Amelogenin / Q000172:deficiency*; D000818:Animals; D001718:Birefringence; D003743:Dental Enamel / Q000378:metabolism* / Q000502:physiology; D005109:Extracellular Matrix / Q000502:physiology*; D005260:Female; D053519:Matrix Metalloproteinase 20 / Q000172:deficiency*; D051379:Mice; D018345:Mice, Knockout; D008859:Microscopy, Polarization
chemical_list: D053523:Amelogenin; D053519:Matrix Metalloproteinase 20