Immunohistochemical and Western blot analyses of collar enamel in the jaw teeth of gars, Lepisosteus oculatus, an actinopterygian fish.

Although most fish have no enamel layer in their teeth, those belonging to Lepisosteus (gars), an extant actinopterygian fish genus, do and so can be used to study amelogenesis. In order to examine the collar enamel matrix in gar teeth, we subjected gar teeth to light and electron microscopic immunohistochemical examinations using an antibody against bovine amelogenin (27 kDa) and antiserum against porcine amelogenin (25 kDa), as well as region-specific antibodies and antiserum against the C-terminus and middle region, and N-terminus of porcine amelogenin, respectively. The enamel matrix exhibited intense immunoreactivity to the anti-bovine amelogenin antibody and the anti-porcine amelogenin antiserum in addition to the C-terminal and middle region-specific antibodies, but not to the N-terminal-specific antiserum. These results suggest that the collar enamel matrix of gar teeth contains amelogenin-like proteins and that these proteins possess domains that closely resemble the C-terminal and middle regions of porcine amelogenin. Western blot analyses of the tooth germs of Lepisosteus were also performed. As a result, protein bands with molecular weights of 78 kDa and 65 kDa were clearly stained by the anti-bovine amelogenin antibody as well as the antiserum against porcine amelogenin and the middle-region-specific antibody. It is likely that the amelogenin-like proteins present in Lepisosteus do not correspond to the amelogenins found in mammals, although they do possess domains that are shared with mammalian amelogenins.

Localization and quantitative co-localization of enamelin with amelogenin.

Enamelin and amelogenin are vital proteins in enamel formation. The cooperative function of these two proteins controls crystal nucleation and morphology in vitro. We quantitatively analyzed the co-localization between enamelin and amelogenin by confocal microscopy and using two antibodies, one raised against a sequence in the porcine 32 kDa enamelin region and the other raised against full-length recombinant mouse amelogenin. We further investigated the interaction of the porcine 32 kDa enamelin and recombinant amelogenin using immuno-gold labeling. This study reports the quantitative co-localization results for postnatal days 1-8 mandibular mouse molars. We show that amelogenin and enamelin are secreted into the extracellular matrix on the cuspal slopes of the molars at day 1 and that secretion continues to at least day 8. Quantitative co-localization analysis (QCA) was performed in several different configurations using large (45 µm height, 33 µm width) and small (7 µm diameter) regions of interest to elucidate any patterns. Co-localization patterns in day 8 samples revealed that enamelin and amelogenin co-localize near the secretory face of the ameloblasts and appear to be secreted approximately in a 1:1 ratio. The degree of co-localization decreases as the enamel matures, both along the secretory face of ameloblasts and throughout the entire thickness of the enamel. Immuno-reactivity against enamelin is concentrated along the secretory face of ameloblasts, supporting the theory that this protein together with amelogenin is intimately involved in mineral induction at the beginning of enamel formation.

Assessment of fidelity and utility of the whole-genome amplification for the clinical tests offered in a histocompatibility and immunogenetics laboratory.

Increasing emphasis on the use of molecular tests in a histocompatibility and immunogenetics laboratory (HIL) poses a potential problem of lack of sufficient DNA to perform multiple genetic analyses. In this study, we report the feasibility, fidelity and utility of multiple displacement amplification (MDA) method to perform whole-genome amplification (WGA) to generate DNA specimens that can be analyzed by multiple molecular techniques and can be used for different clinical tests offered by an HIL. The MDA-generated DNA when compared with the native DNA showed 100% congruency in genotyping of 37 genes/loci using multiple downstream molecular techniques: sequence-based typing and sequence-specific primer-based typing for 5 human leukocyte antigen (HLA) class I and II genes (HLA-A, B, C, DRB1 and DQB1), luminex-based sequence-specific oligonucleotide (SSO) genotyping for a panel of 16 killer immunoglobulin-like receptor (KIR) genes and automated fragment size analysis for a panel of 15 short tandem repeat (STR) loci and amelogenin gene. For post-allogeneic hematopoietic cell transplantation (HCT) chimerism analysis, MDA-generated DNA appeared useful for enriching pre-transplant DNA but not for enriching post-transplant chimeric DNA. Overall, our results show that MDA-based WGA could generate DNA of high yield and fidelity that can be used for various clinical tests and research purposes.

Enamel defects associated with coeliac disease: putative role of antibodies against gliadin in pathogenesis.

Enamel defects in the permanent teeth of patients with coeliac disease (CD) are often reported as an atypical manifestation, sometimes being suggestive of an undiagnosed atypical disease. We proposed to explore the pathogenesis of these oral defects, which are poorly studied. Sequence analyses of proteins from gluten (gliadins) and of proline-rich enamel proteins (amelogenin and ameloblastin) suggested the presence of common antigenic motifs. Therefore, we analyzed, by ELISA and western blotting, the reactivity of sera from patients with CD against gliadin and enamel-derived peptides. Correlation analyses between the levels of specific antibodies against gliadin and enamel derived peptides and inhibition experiments confirmed the presence of cross-reactive antibodies. Immunoblot analysis revealed that the most prominent component in enamel matrix derivative (of approximately 18.6 kDa), identified by an amelogenin-specific antibody, is recognized by sera from patients with CD; in addition, several fractions of pure gliadin were recognized by amelogenin-specific antibody. In agreement, sera from mice immunized with enamel matrix-derived proteins generated antibodies that recognized a peptide (of approximately 21.2 kDa) derived from gliadin. In conclusion, antibodies against gliadin generated in patients with CD can react in vitro with a major enamel protein. The involvement of anti-gliadin serum in the pathogenesis of enamel defects in children with untreated CD can be hypothesized on the basis of these novel results.