title: Synergistic roles of amelogenin and ameloblastin.
abstract: Amelogenin and ameloblastin, the major enamel matrix proteins, are important for enamel mineralization. To identify their synergistic roles in enamel development, we generated Amel X(-/-)/Ambn(-/-) mice. These mice showed additional enamel defects in comparison with Amel X(-/-) or Ambn(-/-) mice. In 7-day-old Amel X(-/-)/Ambn(-/-) mice, not only was the ameloblast layer irregular and detached from the enamel surface, as in Ambn(-/-), but also, the enamel width was significantly reduced in the double-null mice as compared with Amel X(-/-) or Ambn(-/-) mice. Proteomic analysis of the double-null teeth revealed increased levels of RhoGDI (Arhgdia), a Rho-family-specific guanine nucleotide dissociation inhibitor, which is involved in important cellular processes, such as cell attachment. Both Amel X(-/-)/Ambn(-/-) mice and Ambn(-/-) mice displayed positive staining with RhoGDI antibody in the irregularly shaped ameloblasts detached from the matrix. Ameloblastin-regulated expression of RhoGDI suggests that Rho-mediated signaling pathway might play a role in enamel formation.
authors.affiliation: Functional Genomics Section, Laboratory of Cell and Developmental Biology, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA.
authors.forename: J
authors.initials: J
authors.lastname: Hatakeyama
authors.forename: S
authors.initials: S
authors.lastname: Fukumoto
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: N
authors.initials: N
authors.lastname: Haruyama
authors.forename: S
authors.initials: S
authors.lastname: Suzuki
authors.forename: Y
authors.initials: Y
authors.lastname: Hatakeyama
authors.forename: L
authors.initials: L
authors.lastname: Shum
authors.forename: C W
authors.initials: CW
authors.lastname: Gibson
authors.forename: Y
authors.initials: Y
authors.lastname: Yamada
authors.forename: A B
authors.initials: AB
authors.lastname: Kulkarni
mesh_terms: D000566:Amelogenesis / Q000235:genetics / Q000502:physiology*; D053523:Amelogenin / Q000235:genetics / Q000502:physiology*; D000818:Animals; D003743:Dental Enamel / Q000502:physiology / Q000648:ultrastructure*; D003746:Dental Enamel Proteins / Q000235:genetics / Q000502:physiology*; D007180:Incisor / Q000648:ultrastructure; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008817:Mice, Mutant Strains; D008963:Molar / Q000648:ultrastructure
chemical_list: C490890:Ambn protein, mouse; D053523:Amelogenin; D003746:Dental Enamel Proteins