Insulin stimulates production of glycoconjugate layers on the cell surface of gastric surface mucous cell line GSM06

The AT1 Receptor Blocker Telmisartan Reduces Intestinal Mucus Thickness in Obese Mice

The angiotensin II (type 1) (AT₁) receptor blocker telmisartan (TEL) is beneficial for the treatment of individuals suffering from metabolic syndrome. As we have shown that TEL has an impact on gut microbiota, we investigated here whether TEL influences gut barrier function. C57BL/6N mice were fed with chow or high-fat diet (HFD) and treated with vehicle or TEL (8 mg/kg/day). Mucus thickness was determined by immunohistochemistry. Periodic Acid-Schiff staining allowed the number of goblet cells to be counted. Using western blots, qPCR, and immunohistochemistry, factors related to mucus biosynthesis (Muc2, St6galnac), proliferation (Ki-67), or necroptosis (Rip3) were measured. The influence on cell viability was determined in vitro by using losartan, as the water solubility of TEL was too low for in vitro experiments. Upon HFD, mice developed obesity as well as leptin and insulin resistance, which were prevented by TEL. Mucus thickness upon HFD-feeding was diminished. Independent of feeding, TEL additionally reduced mucus thickness. Numbers of goblet cells were not affected by HFD-feeding and TEL. St6galnac expression was increased by TEL. Rip3 was increased in TEL-treated and HFD-fed mice, while Ki-67 decreased. Cell viability was diminished by using >1 mM losartan. The anti-obese effect of TEL was associated with a decrease in mucus thickness, which was likely not related to a lower expression of Muc2 and goblet cells. A decrease in Ki-67 and increase in Rip3 indicates lower cell proliferation and increased necroptosis upon TEL. However, direct cell toxic effects are ruled out, as in vivo concentrations are lower than 1 mM.

The immortalized cell lines with differentiation potentials: their establishment and possible application

Approximately 200 types of the cells are qualified as differentiated cells in the human body. If these different types of cells can be separated from each other (or cloned) and obtained in sufficient quantity, it will be beneficial for studying development, morphogenesis, tissue maintenance, cancer and aging, and for reconstructing functional tissues in vitro for regenerative medicine. We produced the transgenic mouse and rat harboring SV40 T-antigen gene to make the immortalized cell lines in the primary tissue culture and succeeded in establishing many functionally active cell lines from various tissues. Many immortalized cell lines from various tissues are shown to exhibit the unique characteristics of tissue functions and they should be useful as an in vitro model of various tissues for physiological and pharmacological investigations. Future application of these cells to drug screening is discussed.

Correlation of gastric mucosal damage with sialic acid profile in rats: effect of hydrochloric acid, pepsin and hypertonic saline

Sialic acids occupy terminal positions on gastric mucus glycoprotein where they contribute to the high viscosity of mucin. Desialylation of mucus may lead to degradation of the mucus and eventually to the breakdown of the gastric mucus barrier. The effect of a variety of damaging agents (0.1 M HCl, 2 mg ml(-1) pepsin and 2 M NaCl) on sialic acid profile was determined in pylorus-ligated rats. The relationship between sialic acid, galactose, pyruvate and the extent of gastric mucosal damage were studied. Instillation of pepsin significantly increased total sialic acid, galactose and macroscopic mucosal lesions in the stomach. Instillation of 0.1 M HCl reduced the total sialic acid but this decrease was not significant. Acidity led to a significant increase in the amount of free sialic acid in the gastric instillates and the macroscopic lesions induced by acid was not significantly different from the control animals (0.15 M NaCl). 2 M NaCl induced the macroscopic lesions in the stomach and also free sialic acid in the instillates. Pepsin potentiates the action of 2 M NaCl. In all the agents examined with the exception of acid, it was observed that an increase in free sialic acid and galactose was accompanied by gastric mucosal erosion and elevation of pyruvate concentration. It is concluded that gastric acidity alone is not inherently damaging and that resistance of gastric mucosa to destructive agents may be dependent on the integrity of the sialic acids.

Development of cell model with specific functions and its application to the study of global gene expression

The use of in vitro cell culture models has been of central importance in the development of our understanding of the cellular and molecular biology of organs and tissues. Transgenic mice and rats harboring temperature-sensitive simian virus 40 large T-antigen genes are useful for establishing cell lines from organs and tissues that have proved difficult to culture in vitro. Many conditionally immortalized cell lines with normal specific functions were generated from transgenic animals. DNA microarray technology has broad applications and is directed toward the study of global gene expression. Using established cell lines and DNA microarrays, we identified many genes that were up- and down-regulated in the process of the cell differentiation or cell death. In this review, the characteristics of established cell lines and possible applications of the study of global gene expression are discussed.

DNA microarray analysis of differentially expressed genes responsive to bisphenol A, an alkylphenol derivative, in an in vitro mouse Sertoli cell model

To identify genes elicited by bisphenol A (BPA) in Sertoli cells, we carried out a microarray analysis of TTE3 cells (a mouse Sertoli cell line) treated with BPA. BPA (100, 200 and 400 microM) induced cell death concentration-dependently, with levels being 25%, 33% and 96%, respectively. Of the 1,081 genes analyzed, 3 genes showed decreased levels of expression while the remaining 10 genes showed increased levels in the cells treated with a subtoxic dose of BPA (200 microM). The expressions of six genes were confirmed by the TaqMan assay. These findings suggest that DNA microarray analysis is a useful tool for investigating the molecular mechanisms of the toxic effects of BPA in testicular cells.

Characterization and application of a gastric surface mucous cell line GSM06 established from temperature-sensitive simian virus 40 large T-antigen transgenic mice

It has been indicated that transgenic mouse harboring a temperature-sensitive simian virus 40 large T-antigen gene is useful for establishing cell lines from tissues that have proved difficult to culture in vitro. The gastric surface mucous cell line GSM06 was established from a primary culture of gastric fundic mucosal cells of the transgenic mice. GSM06 cells showed temperature-sensitive growth in culture and expressed large T-antigen at a permissive temperature (33 degrees C) but not at a nonpermissive temperature (39 degrees C). At 39 degrees C, the cells produced periodic acid-Schiff positive glycoconjugates that formed a mucous sheet like the gastric surface mucosa in the stomach. Insulin markedly increased the production of glycoconjugates. In addition, proprotein-processing endoprotease furin suppression retarded cell growth, but accelerated cell differentiation. An air-liquid interface promoted the differentiation of GSM06 cells in a reconstruction culture with nitrocellulose membrane and collagen gel. The gastric surface mucous cell line GSM06 with unique characteristics, therefore, should be useful as an in vitro model of the gastric mucosa for physiological and pharmacological investigations. Moreover, experiments using immortalized cells established in vitro and having specific functions may offer an alternative to experiments using living animals and thereby offer a solution to this ethical issue.

Establishment and characterization of a colonic epithelial cell line MCE301 from transgenic mice harboring temperature-sensitive simian virus 40 large T-antigen gene

We produced an immortalized colonic epithelial cell line, MCE301, using fetal mice transgenic for the temperature-sensitive simian virus 40 large T-antigen gene. MCE301 cells showed epithelial-like morphology and maintained tight connections with neighboring cells. The cells grew at a permissive temperature (33 degrees C), but the growth of the cells was significantly prevented at the nonpermissive temperature (39 degrees C). The cells expressed large T-antigen at 33 degrees C but not at 39 degrees C. MCE301 cells were not transformed, as judged by the absence of anchorage-independent growth in soft agar gel and lack of tumor formation in nude mice. Electron microscopic studies showed that the cells formed microvilli-like structures on the cell surface and junctional complexes such as tight junctions and desmosomes between the cells. The cells expressed cytosketal (acidic cytokeratins and actin), basement membrane (laminin and collagen type IV) and junctional complex proteins (ZO-1 and desmoplakin I + II), as judged by specific antibodies. Fetal bovine serum, epidermal growth factor, insulin-like growth factor and insulin significantly increased the cell growth at 33 degrees C. Moreover, MCE301 cells expressed colonic mucin Muc2 mRNA as demonstrated by reverse transcriptase-polymerase chain reaction, indicating that the cells originate from mucus-secreting cells. Alkaline phosphatase, a brush border-associated enzyme, was detected in the cells. Sodium butyrate (2 mM), an inducer of cellular differentiation, markedly elevated alkaline phosphatase activity. Thus, the present mouse colonic epithelial cell line MCE301 possessing these unique characteristics should provide a useful in vitro model of colonic epithelium.