Gene Expression and Localization of Amelogenin in the Rat Incisor

Inage, Toshihiko; Shimokawa, Hitoyata; Wakao, Kouichi; Sasaki, Satoshi

doi:10.1177/08959374960100021401

Cited by 31 publications

(27 citation statements)

References 28 publications

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“…Using the probe generated from bovine amelogenin cDNA coding for exons 1-7 (Shimokawa et al 1987a), Inage et al (1996) showed a precise mapping of amelogenin mRNA expression in rat incisor. In their studies the amelogenin mRNA signals started to appear in the cells of the inner enamel epithelium close to the preameloblasts and lasted until the ameloblasts entered the initial stage of enamel maturation, although the signal expression became weaker during the transitional stage.…”

Section: Discussionmentioning

confidence: 99%

Expression of Alternatively Spliced RNA Transcripts of Amelogenin Gene Exons 8 and 9 and Its End Products in the Rat Incisor

Baba

Takahashi

Terashima

et al. 2002

J Histochem Cytochem.

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S U M M A R YIn addition to seven known exons of the amelogenin gene, recent studies have identified two exons downstream of amelogenin exon 7 in genomic DNA of mouse and rat. Here the spatial and temporal expression of mRNAs and of the translated proteins derived from alternative splicing of the amelogenin gene ending with exon 8 and exon 9 were examined by in situ hybridization (ISH) and immunohistochemistry (IHC). RNA signals for exons 8 and 9 were expressed in the ameloblast layer extending from early presecretory to postsecretory transitional stages of amelogenesis. IHC of amelogenin proteins that include sequences encoded by these exons demonstrated identical localization of these proteins in the ameloblast layer corresponding to RNA signals identified by ISH. There was intense immunostaining of the enamel matrix secreted by these cells. Western blotting analysis of rat enamel proteins revealed three distinct protein bands with sequences encoded by the new exons. These data confirmed the existence of the transcripts of alternatively spliced mRNAs coding for exons 8 and 9 of the amelogenin gene in rat tooth germs and suggest that the translated proteins contribute to the heterogeneity of amelogenins and have some significant roles in enamel formation and mineralization.

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Section: Discussionmentioning

confidence: 99%

Expression of Alternatively Spliced RNA Transcripts of Amelogenin Gene Exons 8 and 9 and Its End Products in the Rat Incisor

Baba

Takahashi

Terashima

et al. 2002

J Histochem Cytochem.

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“…These observations are not consistent with a relationship to the onset of apoptosis. The weak signal observed at the beginning of postsecretory transition may be related to secretory activity because ameloblasts at this stage in the rat incisor still synthesize matrix proteins, albeit at a much reduced rate (Smith 1984;Nanci et al 1987Nanci et al , 1998Inage et al 1996). With regard to the relatively similar immunolabeling signal for IGF-IIR across amelogenesis, the finding is surprising because the lysosomal pool of ameloblasts rapidly expands in preparation for the secretory stage and then gradually enlarges through secretory and into the maturation zone (Smith 1984).…”

Section: The Journal Of Histochemistry and Cytochemistrymentioning

confidence: 99%

Gene Expression and Localization of Insulin-like Growth Factors and Their Receptors throughout Amelogenesis in Rat Incisors

Yamamoto

Oida

Inage

2006

J Histochem Cytochem.

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(SO) S U M M A R Y Insulin-like growth factors (IGFs) are expressed in many tissues and control cell differentiation, proliferation, and apoptosis. In teeth, the temporo-spatial pattern of expression IGFs and their receptors has not been fully characterized. The purpose of this study was to obtain a comprehensive profile of their expression throughout the life cycle of ameloblasts, using the continuously erupting rat incisor model. Upper incisors of young male rats were fixed by perfusion, decalcified, and embedded in paraffin. Sections were processed for in situ hybridization and immunohistochemistry. mRNA and protein expression profiles IGF-I, IGF-II, IGF-IR, and IGF-IIR mRNA were essentially identical. At the apical loop of the incisor, very strong signals were seen in the outer enamel epithelium while the inner enamel epithelium showed a moderate reaction. In the region of ameloblasts facing pulp, inner enamel epithelium cells were still moderately reactive while signals over the outer enamel epithelium were slightly reduced. In the region of ameloblasts facing dentin and the initial portion of the secretory zone, signals in ameloblasts were weak while those over the outer enamel epithelium were strong. In the region of postsecretory transition, signals in both ameloblasts and papillary layer cells gradually increased. In maturation proper, signals in ameloblasts appeared as alternating bands of strong and weak reactivities, which corresponded to the regions of ruffle-ended and smooth-ended ameloblasts, respectively. Papillary layer cells also showed alternations in signal intensity that matched those in ameloblasts. These results suggest that the IGF family may act as an autocrine/paracrine system that influences not only cell differentiation but also the physiological activity of ameloblasts. (J Histochem Cytochem 54:243-252, 2006)

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“…Several investigations of rodent incisor and molar tooth germs have shown that not only secretory ameloblasts but also maturation ameloblasts express amelogenins (Nanci et al 1987;DenBesten and Li 1992;Fong et al 1996;Inage et al 1996;Wurtz et al 1996;Karg et al 1997). However, it was not clear that maturation ameloblasts of porcine tooth germs express amelogenins.…”

Section: Introductionmentioning

confidence: 95%

Maturation ameloblasts of the porcine tooth germ do not express amelogenin

Wakida¹,

Amizuka

Murakami³

et al. 1999

Histochemistry and Cell Biology

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Amelogenins are the most abundant constituent in the enamel matrix of developing teeth. Recent investigations of rodent incisors and molar tooth germs revealed that amelogenins are expressed not only in secretory ameloblasts but also in maturation ameloblasts, although in relatively low levels. In this study, we investigated expression of amelogenin in the maturation stage of porcine tooth germs by in situ hybridization and immunocytochemistry. Amelogenin mRNA was intensely expressed in ameloblasts from the differentiation to the transition stages, but was not detected in maturation stage ameloblasts. C-terminal specific anti-amelogenin antiserum, which only reacts with nascent amelogenin molecules, stained ameloblasts from the differentiation to the transition stages. This antiserum also stained the surface layer of immature enamel at the same stages. At the maturation stage, no immunoreactivity was found within the ameloblasts or the immature enamel. These results indicate that, in porcine tooth germs, maturation ameloblasts do not express amelogenins, suggesting that newly secreted enamel matrix proteins from the maturation ameloblast are not essential to enamel maturation occurring at the maturation stage.

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Gene Expression and Localization of Amelogenin in the Rat Incisor

Cited by 31 publications

References 28 publications

Expression of Alternatively Spliced RNA Transcripts of Amelogenin Gene Exons 8 and 9 and Its End Products in the Rat Incisor

Expression of Alternatively Spliced RNA Transcripts of Amelogenin Gene Exons 8 and 9 and Its End Products in the Rat Incisor

Gene Expression and Localization of Insulin-like Growth Factors and Their Receptors throughout Amelogenesis in Rat Incisors

Maturation ameloblasts of the porcine tooth germ do not express amelogenin

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