Localization of Transcription Factor AP-1 Family Proteins in Ameloblast Nuclei of the Rat Incisor

Abstract

We examined by immunocytochemistry the localization of the AP-1 family proteins c-Jun, JunB, JunD, c-Fos, FosB, Fra-1, and Fra-2 in rat incisor ameloblasts. Most of the antibodies against AP-1 family proteins, except for c-Fos-specific antibody, labeled ameloblast nuclei. The labeling intensity of the c-Jun, JunD, and Fra-2 antibodies was stronger than that of JunB, FosB, and Fra-1. Antibody reactivities of c-Jun, JunD, and Fra-2 were greatly enhanced during or after the transition zone. Furthermore, c-Jun antibodies labeled maturation ameloblasts in a cyclic pattern, which was correlated with ameloblast modulation. Disruption of ameloblast modulation by colchicine injection resulted in greatly decreased reactivity of the c-Jun antibody in the ameloblast nuclei of the maturation zone. Phospho-specific antibodies to c-Jun labeled ameloblast nuclei only weakly throughout the secretion, transition, and maturation zones. These results suggest that the stage-specific localization of AP-1 in ameloblasts is closely related to tooth enamel formation.

Transient increase in anti-p-ATF2 immunoreactivity in the late secretion ameloblasts apical to the transition zone of rat incisors

“…In contrast, anti-p-ATF2 labeling without the blocking peptide exhibited positive nuclear reactivity in the late secretion ameloblasts (c). Bars,50 µm. in the maturation zone c-Jun, JunD and Fra2 are the predominant AP-1 family proteins, as described earlier (Nishikawa, 2000). Anti-ATF2 antibodies uniformly labeled nuclei of ameloblasts and other enamel organ-derived cells from the proliferation to maturation zones.…”

Localization of Transcriptional Co-activator CBP in the Ameloblasts and the Other Enamel Organ-derived Cells of the Rat Incisor

“…The present study showed that CBP did localize in the nuclei of the ameloblasts mostly in maturation zone, whereas the possibility exists that loss of cytoplasmic CBP occurred during long sample incubation time in a EDTA solution for demineralization. Considering that c-Jun labeling is strong in the maturation zone (Nishikawa 2000), it is reasonable to speculate that CBP and c-Jun interact with each other, directly or indirectly, although the localization of CBP and c-Jun was complementary in some specimens in this study and this study did not provide any evidence suggesting any interactions of two proteins. Furthermore, CBP was also detected in the nuclei of enamel organ-derived cells other than ameloblasts.…”

“…They are referred to as ruffle-ended ameloblasts (RA, major cell appearance with ruffled border at apical cell end) and smooth-ended ameloblasts (SA, minor cell appearance occupying one fifth of the total maturation zone) (Josephsen and Fejerskov 1977). Moreover, c-Jun labeling is stronger in RA than in SA (Nishikawa 2000). A large part of RA is considered to contribute to mineral uptake in the enamel matrix, although SA contributes to some passive calcium uptake (Reith and Boyde 1981;Takano et al 1982).…”

Characterization of mesenchymal stem cells from rat bone marrow: ultrastructural properties, differentiation potential and immunophenotypic markers

“…AP-1 components are specific for some biological processes including cellular proliferation, differentiation, apoptosis and oncogenic transformation that are identified as a proto-oncogene (Ovitt and Rüther 1989;Nishikawa 2000;Srouji et al 2005). Particularly, c-fos has been associated with the coordinated regulation of gene expression during cellular proliferation and differentiation (Stachowiak et al 1990;Bakiri et al 2002).…”