Characteristic distribution of immunoreaction for estrogen receptor alpha in rat ameloblasts

Abstract

Estrogen has a diverse function, including cell proliferation and differentiation via estrogen receptors (ER), which have been reported to be the case in various tissues in addition to female reproductive organs. A recent immunocytochemical study has reported the expression of ER␣, a subtype of ER, in rat odontoblasts, suggesting an involvement of estrogen in the differentiation of tooth-forming cells. However, there is no information on the ER␣ immunoexpression in ameloblasts. The present study was therefore undertaken to examine the localization of ER␣ immunoreaction in rat ameloblasts during amelogenesis. A computer-assisted quantitative analysis under a confocal laser scanning microscope was employed to demonstrate the stage-specific localization pattern of ER␣ immunoreaction. Immunohistochemistry of the rat enamel organ revealed ER␣ expression as nuclear localization in ameloblasts, stratum intermedium, stellate reticulum, and papillary layer, in addition to mature and immature odontoblasts. The ratio of immunopositive nuclei to total nuclei (immunopositive ratio) in ameloblasts was high at the apical loop region and gradually declined at the presecretory stage to zero at the secretory stage with statistically significant difference. The ER␣ immunolabeling pattern exhibited a periodic change at the maturation stage proper with constant higher labeling in ruffle-ended ameloblasts than in smooth-ended ameloblasts. The positive ratio was then followed by a statistically significant increase in immunolabeling thereafter. This stage-specific immunolabeling pattern during amelogenesis suggests a possible role of ER␣ in ameloblast proliferation and differentiation.

Identification of novel candidate genes associated with cleft lip and palate using array comparative genomic hybridisation

“…We identified ESR1 as the highest priority candidate gene within the region using Endeavour. It has been reported that expression of oestrogen receptor α occurs during the differentiation of tooth-forming cells 36. Previous studies have shown that the oestrogen receptor acts as a transcriptional corepressor for Smad3 (Sma and MAD-related protein 3), which is one of the major intracellular transducers of transforming growth factor-β (TGF-β) signalling 37 38.…”

Oestrogen receptor alpha, growth hormone receptor, and developmental defect of enamel

“…[10][11][12] Similar models have shown growth hormone deficiency as associated with caries resistance. 13 More recent studies have demonstrated that the receptors of these hormones are expressed during amelogenesis, and ERα [14][15][16] and GHR have been identified in enamel formation in rats. 17 Therefore, it is possible that genetic variations in ESR1, which is the gene that codifies ERα, and in GHR are involved in caries susceptibility and developmental defects of enamel (DDE).…”

Association of Dental Fluorosis with Polymorphisms of Estrogen Receptor Gene in Chinese Children

“…Further research has shown that Hsp25 might be directly upregulated by estrogen because of estrogen responsive element in the 5′ promoter region of this gene [35]. Recent studies suggested that the ERα immunoreactions were exhibited both in odontoblasts and ameloblasts, suggesting toothforming cells as targets for estrogen action [25,36,37]. Enamel discoloration and defect are major clinical manifestations of DF.…”

“…The results suggested that ESR gene polymorphism might be associated with acquisition of peak bone mass, in particular trabecular bone. Enamel, which is derived from the ectoderm, undergoes matrix formation and subsequent maturation to become the hardest tissue in mammals [25]. Ohshima et al demonstrated transient expression of 25-kDa heatshock protein (Hsp25) during rat amelogenesis, suggesting that this protein is involved in the differentiation of ameloblasts in animal experiment [34].…”

“…The pathological change of DF is the same as skeletal fluorosis, and it related to osteoblast activities, secreted structural matrix proteins and multiple proteases, and fluid composition including calcium ions and fluoride ions [1]. Because of the important roles of estrogen in the differentiation of tooth-forming cells [25], polymorphisms in ESRα and ESRβ may influence the occurrence of DF. Although previous research has reported ESR allele frequencies in different populations [26][27][28], the role of ESR gene polymorphisms in relation to DF has been unclear.…”