• Environmental Mutagens and Carcinogens
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• v.23 no.1
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• pp.11-15
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• 2003

Gap junctional intercellular communication (GJIC) plays a key role during development, process of tissue differentiation, and in maintenance of adult tissue homeostasis. Neural stem cells leading to formation of cell clusters termed 'neurospheres', can differentiate into neurons, oligodendrocytes, and astrocytes. We investigated the expression levels and distribution of connexin43 (Cx43) and connexin32 (Cx32), abundant gap junctional protein in neural cells and in neurospheres isolated from rat fetus embryonic day (ED) 17. During differentiation of neurospheres, expression of Cx43 and 32 were increased time-dependently within 72 h, and then decreased at 7 day in western blot analysis. TPA-induced inhibition of GJIC was confirmed by decreased fluorescence by SL/DT assay, and induced hyperphosphorylation of Cx43 while no changes in Cx32 levels in western blot assay. Our results indicate that GJIC may be a crucial role in the differentiation of neuronal stem cell. And this GJIC can be inhibited by TPA through the hyperphosphorylation of Cx43.

• Development and Reproduction
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• v.20 no.4
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• pp.349-357
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• 2016

The present research was chiefly designed to determine the effect of the treatment of estrogenic agonist, estradiol benzoate (EB), or antiandrogenic compound, flutamide (Flu), at the weaning age on the expression of connexin (Cx) isoforms in the caudal epididymis of adult male rat. Animals were subcutaneously administrated with a single shot of either EB at a low-dose ($0.015{\mu}g$ of EB/kg body weight (BW)) or a high-dose ($1.5{\mu}g$ of EB/kg BW) or Flu at a low-dose ($500{\mu}g$ of EB/kg BW) or a high-dose (5 mg of EB/kg BW). Expressional changes of Cx isoforms in the adult caudal epididymis were examined by quantitative real-time PCR analysis. The treatment of a low-dose EB caused significant increases of Cx30.3, Cx31, Cx32, and Cx43 transcript levels but reduction of Cx31.1, Cx37, and Cx45 expression. Exposure to a high-dose EB resulted in very close responses observed in a low-dose EB treatment, except no significant expressional change of Cx37 and a significant induction of Cx40. Expression of all Cx isoforms, except Cx45, was significantly increased by a low-dose Flu treatment. Expressional increases of all Cx isoforms were detected by a high-dose Flu treatment. The current study demonstrates that a single exposure to estrogenic or antiandrogenic compound during the early postnatal developmental period is sufficient to disrupt normal expression of Cx isoforms in the adult caudal epididymis.

• Journal of Animal Science and Technology
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• v.55 no.6
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• pp.521-530
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• 2013

Direct cell-cell communication via the transfer of small molecules between neighboring cells in tissue is accomplished by gap junctions composed of various connexins (Cxs). Proper postnatal development of the epididymis is important for acquisition of male reproduction. The epididymal epithelium is composed of several cell types, and some of these cells are connected by gap junctions. The present study was conducted to determine the presence of Cx transcripts in the corpus and cauda epididymis. In addition, transcriptional changes of Cxs expressed during different postnatal stages were examined by real-time PCR analysis. In both epididymal regions, the same nine Cx transcripts of thirteen Cxs tested were detected. In the corpus epididymis, the highest levels of Cxs31.1 and 37 transcripts were observed at 45 days of age, and amounts of Cxs26, 30.3, and 32 transcripts increased with age and subsequently decreased in the elderly. Expression of Cx31 was greatly increased in the adult and elder stages, while Cxs40, 43, and 45 were abundant in the early postnatal stages. In the cauda epididymis, expression of Cxs26, 30.3, 31.1, 37, and 40 reached the highest levels at 5 months of age. The levels of Cxs31 and 32 mRNAs fluctuated throughout the postnatal period. The amounts of Cxs43 and 45 transcripts were more abundant during the late neonatal and prepubertal ages than later ages. These findings suggest that regional specification of the epididymis is partly regulated by differential expression of Cx genes during the postnatal developmental period.

• Journal of Periodontal and Implant Science
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• v.32 no.1
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• pp.129-142
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• 2002

Epithelial-mesenchymal interaction plays a important role in cell growth and differentiation. This interaction is already well known to have an importance during the organ development as well as cell growth and differentiation. However, in vitro experimental model is not well developed to reproduce in vivo cellular microenvironment which provide a epithelial-mesenchymal interaction. Because conventional monolayer culture lacks epithelial-mensenchymal interaction, cultivated cells have an morphologic, biochemical, and functional characteristics differ from in vivo tissue. Moreover, it's condition is not able to induce cellular differention due to submerged culture condition. Therefore, the aims of this study were to develop and evaualte the in vitro experimental model that maintains epithelial-mesenchymal interaction by organotypic raft culture, and to characterize biologic properties of three-dimensionally reconstituted oral keratinocytes by histological and immunohistochemical analysis. The results were as follow; 1. Gingival keratinocytes reconstituted by three-dimensional organotypic culture revealed similar morphologic characteristics to biopsied patient specimen showing stratification, hyperkeratinosis, matutation of epithelial architecture. 2. Connective tissue structure was matured, and there is no difference during stratification period of epithelial 3-dimensional culture. 3. The longer of air-exposure culture on three-dimensionally reconstituted cells, the more epithelial maturation, increased epithelial thickness and surface keratinization 4. In reconstitued mucosa, the whole epidermis was positively stained by anti-involucrin antibody, and there is no difference according to air-exposured culture period. 5. The Hsp was expressed in the epithelial layer of three-dimensionally cultured cells, especially basal layer of epidermis. The change of Hsp expression was not significant by culture stratification. 6. Connexin 43, marker of cell-cell communication was revealed mild immunodeposition in reconstitued epithelium, and there is no significant expression change during stratification. These results suggest that three-dimensional oragnotypic co-culture of normal gingival keratinocytes with dermal equivalent consisting type I collagen and gingival fibroblasts results in similar morphologic and immunohistochemical characteristics to in vivo patient specimens. And this culture system seems to provide adequate micro-environment for in vitro tissue reconstitution. Therefore, further study will be focused to study of in vitro gingivitis model, development of novel perioodntal disease therapeutics and epithelial-mensenchymal interaction.

• Journal of Life Science
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• v.16 no.1
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• pp.37-43
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• 2006

Gap junction is an ion channel forming between adjacent cells. It also acts as a membrane channel like sodium or potassium channels in a single cell. The amino acid residues up to the $10^{th}$ position in the amino (N)-terminus of gap junction hemichannel affect gating polarity as well as current-voltage (I-V) relation. While wild-type Cx32 channel shows negative gating polarity and inwardly rectifying I-V relation, T8D channel in which threonine residue at $8^{th}$ position is replaced with negatively charged aspartate residue shows reverse gating polarity and linear I-V relation. It is still unclear whether these changes are resulted from the charge effect or the conformational change of the N-terminus. To clarify this issue, we made a mutant channel harboring cysteine residue at the $8^{th}$ position (T8C) and characterized its biophysical properties using substituted-cysteine accessibility method (SCAM). T8C channel shows negative gating polarity and inwardly rectifying I-V relation as wild-type channel does. This result indicates that the substitution of cysteine residue dose not perturb the original conformation of wild-type channel. To elucidate the charge effect two types of methaenthiosulfonate (MTS) reagents (negatively charged $MTSES^-$ and positively charged $MTSET^+$) were used. When $MTSES^-$ was applied, T8C channel behaved as T8D channel, showing positive gating polarity and linear I-V relation. This result indicates that the addition of a negative charge changes the biophysical properties of T8C channel. However, positively charged $MTSET^+$ maintained the main features of T8C channel as expected. It is likely that the addition of a charge by small MTS reagents does not distort the conformation of the N-terminus. Therefore, the opposite effects of $MTSES^-$ and $MTSETT^+$ on T8C channel suggest that the addition of a charge itself rather than the conformational change of the N-terminus changes gating polarity and I-V relation. Furthermore, the accessibility of MTS reagents to amino acid residues at the $8^{th}$ position supports the idea that the N-terminus of gap junction channel forms or lies in the aqueous pore.