• Journal of Life Science
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• v.28 no.9
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• pp.1016-1021
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• 2018

Clostridium difficile toxin A causes pseudomembranous colitis. The pathogenesis of toxin A-induced colonic inflammation includes toxin A-dependent epithelial cell apoptosis, resulting in the loss of barrier function provided by epithelial cells against luminal pathogens. Toxin A-dependent epithelial cell apoptosis has been linked to toxin A-induced production of reaction oxygen species and subsequent p38MAPK activation; $p21^{CIP1/WAF1}$ upregulation-dependent cell cycle arrest; cytoskeletal disaggregation; and/or the induction of Fas ligand on epithelial cells. However, the molecular mechanisms underlying toxin A-induced apoptosis remain poorly understood. This study tested whether toxin A could block the Wnt signaling pathway, which is involved in gut epithelial cell proliferation, differentiation and antiapoptotic progression. Toxin A treatment of nontransformed human colonocytes (NCM460) rapidly reduced ${\beta}$-catenin protein, an essential component of the Wnt signaling pathway. Exposure of mouse ileum to toxin A also significantly reduced ${\beta}$-catenin protein levels. MG132 inhibition of proteasome-dependent protein degradation resulted in the recovery of toxin A-mediated reduction of ${\beta}$-catenin, indicating that toxin A may activate intracellular processes, such as $GSK3{\beta}$, to promote degradation of ${\beta}$-catenin. Immunoblot analysis showed that toxin A increased active phosphorylation of $GSK3{\beta}$. Because the Wnt signaling pathway is essential for gut epithelial cell proliferation and anti-apoptotic processes, our results suggest that toxin A-mediated inhibition of the Wnt signaling pathway may be required for maximal toxin A-induced apoptosis of gut epithelial cells.

• Journal of Periodontal and Implant Science
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• v.36 no.3
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• pp.783-796
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• 2006

The periodontium is a topographically complex organ consisting of epithelial tissue, soft and mineralized tissues. Structures comprising the periodontium include the gingiva, periodontal ligament (PDL) , cementum and the alveolar bone. The molecular mechanism of differentiation in PDL fibroblast cells remain unclear. Amino acid transporters play an important role in supplying nutrition to normal and cancer cells and for cell proliferation. Amino acid transport system L is a major nutrient transport system responsible for the Na+-independent transport of neutral amino acids including several essential amino acids. The system L is divided into two major subgroups, the L-type amino acid transporter 1 (LAT1) and the L-type amino acid transporter 2 (LAT2). In this study, the expression pattern of amino acid transport system L was, therefore, investigated in the differentiation of PDL fibroblast cells. To determine the expression level of amino acid transport system L participating in intracellular transport of amino acids in the differentiation of PDL fibroblast cells, it was examined by RT-PCR, observation of cell morphology, Alizaline red-S staining and uptake analysis after inducing experimental differentiation in PDL fibroblast cells isolated from mouse molar teeth. The results are as follows. 1. The LAT1 mRNA was expressed in the early stage of PDL fibroblast cell differentiation. This expression level was gradually reduced by differentiation- inducing time and it was not observed after the late stage. 2. The expression level of LAT2 mRNA was increased in time-dependent manner during differentiation induction of PDL fibroblast cells. 3. There was no changes in. the expression level of 4F2hc mRNA, the cofactor of LAT1 and LAT2, during differentiation of PDL fibroblast cells. 4. The expression level of ALP mRNA was gradually increased and the expression level of Col I mRNA was decreased during differentiation of PDL fibroblast cells. 5. The L-leucine transport was reduced by time from the early stage to the late stage in PDL fibroblast cell differentiation. As the results, it is considered that among neutral ammo acid transport system L in differentiation of PDL fibroblast cells, the LATl has a key role in cell proliferation in the early stage of cell differentiation and the LAT2 has an important role in the late stage of cell differentiation for providing cells with neutral amino acids including several essential amino acids.

• Korean Journal of Veterinary Research
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• v.44 no.1
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• pp.83-88
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• 2004

Galectin family, endogenous ${\beta}$-galactoside-binding animal lectins, is known for the role in cell differentiation, morphogenesis, apoptosis and tumorigenesis. Galectin-3, one of family member, has been studied for its role in cell differentiation and tumor metastasis, and for its expression on epithelial cells of colon and mast cells but not in brain. Several reports, however, suggest its expression in brain including as a prion binding protein. In this report we explored possibility of galectin-3 expression in brain tissue. With Western blot and RT-PCR with rat brain tissues, we could detect galectin-3 that was not shown by conventional immunohistochemistry. Our results indicated galectin-3 was expressed in brain, and substantiate the previous report on galecin-3 as a prion-related protein in brain.

• CELLMED
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• v.3 no.1
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• pp.3.1-3.3
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• 2013

The receptor activator of NF-${\kappa}B$ ligand (RANKL), a member of the tumor necrosis factor ligand family, has extensive functions beyond osteoclast development. RANKL is expressed in many immune cells such as osteoblasts, osteocytes, marrow stromal cells, activated T cells, synovial cells, keratinocytes, and mammary gland epithelial cells as well as in various tissues. The ligation of RANK by RANKL promotes dendritic cells (DCs) survival through prosurvival signals and the up-regulation of the anti-apoptotic proteins Bcl-2 and Bcl-$x_L$ and plays a crucial role in DCs-mediated Th1 differentiation. Therefore, RANKL plays an important role in the regulation of DCs/T cells-mediated specific immunity. This review will briefly inform our current understanding of the role of RANKL signaling in T cells-DCs communication in the immune system.

• Korean Journal of Bronchoesophagology
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• v.7 no.1
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• pp.24-28
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• 2001

Background and Objectives： Heat shock protein(HSP) 27 is a member of the small HSP family that plays a part in the epithelial cell growth and differentiation, wound healing. apoptosis and cell protection against inflammatory cytotoxic mediators. The expression of HSP27 was investigated in normal laryngeal tissue and squamous cell carcinoma of the larynx. Materials and Methods : We studied expression of HSP27 by Western blot on 20 patients of laryngeal squamous cell carcinoma. Results： HSP27 expressed in all normal and cancer tissues. In 9 cases(45%), expression of HSP27 more prominent in cancer tissue. Statistically, there were no significant difference in the expression of HSP27 in normal and cancer tissue, clinical stage and tumor differentiation. Conclusion 45% of cancer tissues was more prominent than normal tissue. But further studies on expression of HSP27 in laryngeal cancer and relationship with clinical parameter should be done.

• Journal of Integrative Natural Science
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• v.16 no.3
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• pp.97-102
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• 2023

The gasdermins are a family of recently identified pore-forming effector proteins that cause membrane permeabilization and pyroptosis, a lytic pro-inflammatory type of cell death. A role in the regulation of cell proliferation and/or differentiation is suggested by the differentiation status-specific expression of gasdermin proteins in epithelial tissues. One of the GSDM protein is Gasdermin A (GSDMA), which decreased in stomach and esophageal cancers, suggesting a tumor suppressor role. GSDMA receptor antagonists have been researched as potential treatments for inflammatory diseases and baldness. GSDMA's significance in a wide range of disorders makes it an important therapeutic target. As a result, homology modelling of the GSDMA receptor was undertaken in the current study using the crystal structures of Mus musculus (GSDMA3), Human gasdermin D (GSDMD), and Murine gasdermin D (murine GSDMD). The best model was chosen based on the validation results after 20 models were developed utilising single template-based approaches. The generated structures can be used for further binding site and docking studies in the future.

• Applied Microscopy
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• v.31 no.2
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• pp.143-156
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• 2001

The aim of this study was to clarify the differentiation of seminiferous epithelial cells and spermiogenesis in the testis of Rana catesbeiana. Spermatogenesis of R. catesbeiana consists of primary spermatogonia, secondary spermatogonia, primary spermatocytes, secondary spermatocytes and spermatids. They were subdivided into eight stages on the basis of the morphological features of the germ cell differentiation. From the spermatocytes except primary spermatogonia to before the spermiation of spermatids were surrounded by spermatocyst. Spermiogenesis of R. catesbeiana can also be divided into three stages on the basis of morphological features of the nucleus and the cytoplasm organelles. Spermatozoon contained a saccular acrosome, a cylindrical and tapered slighty at both ends head, and a tail with only the axoneme.

• International Journal of Oral Biology
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• v.32 no.3
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• pp.103-107
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• 2007

We hypothesized that plaque-associated bacteria may have a role in maintenance of alveolar bone. To test it, immortalized gingival epithelial HOK-16B cells were co-cultured with live or lysed eight plaque bacterial species and the expression levels of bone morphogenetic protein (BMP)-2 and -4 were examined by real time reverse transcription-polymerase chain reaction. Un-stimulated HOK-16B cells expressed both BMP-2 and -4. Co-culture with plaque bacterial lysates had significant effects on the level of BMP-2 but not on that of BMP-4. Five species including Streptococcus sanguinis, S. gordonii, Veillonella atypica, Porphyromonas gingivalis, and Treponema denticola substantially up-regulated the level of BMP-2. In contrary to the upregulatory effect of lysate, live T. denticola suppressed the expression of BMP-2. In addition, in vitro osteoblastic differentiation assay using C2C12 cells and the conditioned medium of HOK-16B cells confirmed the production of BMPs by gingival epithelial cells and the modulation of BMP expression by the lysates of S. sanguinis and T. denticola. In conclusion, we have shown that plaque bacteria can regulate the expression of BMP-2 by gingival epithelial cells, the physiologic meaning of which needs further investigation.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.26 no.2
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• pp.132-136
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• 2000

The cell surface glycoprotein CD44 is a kind of adhesion molecule, which binds hyaluronic acid, type I collagen and fibronectin. Although there have been numerous reports on the expression and the function of CD44 in lymphocytes and macrophages, very little is known about its distribution and definite role in epithelial tissue, especially in oral epithelial one. The present study was performed to investigate the distribution and expression of the CD44 in human gingiva and squamous cell carcinoma(SCC) arising in human gingiva. And the authors compared CD44 expression with histopathologic grade of SCC. The results were as follows: 1. The CD44 was strongly expressed in granular, spinous and basal layers of normal marginal and attached gingiva, in spinous and basal layers of normal sulcular gingiva, and in all epithelial layers of normal junctional gingiva. 2. In SCC of gingiva, the CD44 was expressed in all but one case. In most of the cases the CD44 was expressed at cell membrane and the degree of expression was relatively strong. 3. In low-grade SCC of gingiva, the CD44 was strongly expressed, especially at the basal and spinous layers of abundantly keratinized cancer nests. In high-grade SCC of gingiva, the CD44 expression tended to be weak but was strong at cells showing individual keratinization. This study suggest that the CD44 expression of normal and cancerous gingival epithelium is associated with the degree of proliferation and differentiation of epithelial cells.

• Applied Microscopy
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• v.27 no.2
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• pp.131-144
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• 1997

The present study was carried out to investigate the processes of the ultrastructural differentiation and the acetylcholinesterase (AChE) activities of the developing rat retina. The results are as follows. The retina of fetal rat on the 13th day of gestation showed the early stage of differentiation. Briefly, there appeared dividing chromosomes, the plentiful free ribosomes, and the high ratio of nucleus to cytoplasm. The reaction products by AChE were localized at the membrane of endoplasmic reticulum and on the outer membrane of nucleus. Ultrastructures and AChE activities in the retina of the fetal rats on the 18th day of gestation were similar to those of the prior stages, except the appearence of rough endoplasmic reticulum and Golgi apparatus. According to the ultrastructural observations, the rat retina was still in immature state at birth, but the pigment epithelial cells were fully differentiated, e. g. the increase of melanin granules, the development of mitochondria and Golgi apparatus. The AChE activity was weekly detected. The differentiated retinal layers and the outer segment of photoreceptor cells were observed on the 7th postnatal day. And the pigment epithelium appeared to be fully differentiated. On the 14th postnatal day, rat retina were completely differentiated. In other words, the rat retina was characterized by the prominent outer segments, phagocytosed residues in the pigment epithelium, and the localization of reaction products by AChE in the synapses. In conclusion, the differentiation of rat retina is charaterized by the changes of cell shape, the increase of retinal layers, and the alterations of AChE activities. It seems that rat retina is to be functional from 2 weeks of birth onward, coinciding with the eye opening of the juvenile rats.