Toshihiro Sugiyama

Nerve growth factor promotes differentiation of odontoblast‐like cells

Contemporary strategies in tooth repair markedly rely on the newest findings on the cellular and biological components of dental development. Among several identified bioactive molecules, neurotrophins were recently proposed to affect tooth germ cell proliferation, differentiation, and cell–extracellular matrix interactions. The present study attempted to explore the effect of nerve growth factor (NGF) on a spontaneously immortalized dental papilla mesenchymal cell line. NGF induced differentiation of odontoblast‐lineage cells with subsequent biomineralization in vitro. Here we showed that normalized transcript levels of tissue‐specific markers such as DSPP and DMP1 were elevated significantly, indicating cell differentiation and maturation processes. We performed innovative gene expression analysis of TM14, a matricellular protein and novel member of the fibulin family. TM14 expression followed a pattern similar to that of DMP1, which suggests its important role in cell–matrix and intercellular interactions during dentin calcification. Alkaline phosphatase enzyme assay confirmed the extracellular matrix calcifications in NGF‐supplemented groups. Thus, NGF was characterized as a potent promoter of mineralization during dentin formation. For the first time, we included TM14 in odontoblast genotype analysis and proved that NGF also promotes in vitro odontoblast differentiation. Collectively, these results highlight the importance of NGF during tooth morphogenesis, as well as urge the elaboration of complex epithelial–mesenchymal tissue cultures, where further elucidation of the signaling factor network could be completed. J. Cell. Biochem. 106: 539–545, 2009.

Niemann-Pick C1 protein transports copper to the secretory compartment from late endosomes where ATP7B resides.

Wilson disease is a genetic disorder characterized by the accumulation of copper in the body by defective biliary copper excretion. Wilson disease gene product (ATP7B) functions in copper incorporation to ceruloplasmin (Cp) and biliary copper excretion. However, copper metabolism in hepatocytes has been still unclear. Niemann-Pick disease type C (NPC) is a lipid storage disorder and the most commonly mutated gene is NPC1 and its gene product NPC1 is a late endosome protein and regulates intracellular vesicle traffic. In the present study, we induced NPC phenotype and examined the localization of ATP7B and secretion of holo-Cp, a copper-binding mature form of Cp. The vesicle traffic was modulated using U18666A, which induces NPC phenotype, and knock down of NPC1 by RNA interference. ATP7B colocalized with the late endosome markers, but not with the trans-Golgi network markers. U18666A and NPC1 knock down decreased holo-Cp secretion to culture medium, but did not affect the secretion of other secretory proteins. Copper accumulated in the cells after the treatment with U18666A. These findings suggest that ATP7B localizes in the late endosomes and that copper in the late endosomes is transported to the secretory compartment via NPC1-dependent pathway and incorporated into apo-Cp to form holo-Cp.

Acute effects on the lung and the liver of oral administration of cerium chloride on adult, neonatal and fetal mice

We evaluated tissue changes associated with cerium chloride administration via gavage to adult mice, via milk to neonatal mice and transplacentally to fetal mice. Change in adults consisted of extensive pulmonary hemorrhage, pulmonary venous congestion, thickened alveolar septae, hepatic necrosis and neutrophil infiltrations. Those in fetal mice consisted of pulmonary and hepatic congestion. These results indicate that gavage cerium administration elicited subtle tissue changes, though oral toxicity is rather low. These changes were less severe in neonatal and fetal mice. When cerium was injected into adult mice through the tail vein, cerium was distributed mainly to the liver, spleen and lung dose-dependently with the cerium concentration gradually decreasing after 3 days. A study of cerium anticoagulation in mouse plasma showed that clotting time was significantly prolonged when cerium was added to plasma. These results suggest that cerium may disturb blood coagulation and cause pulmonary and hepatic vascular congestion.

REG I enhances chemo- and radiosensitivity in squamous cell esophageal cancer cells.

Identification of reliable markers of chemo‐ and radiosensitivity and the key molecules that enhance the susceptibility of squamous esophageal cancer cells to anticancer treatments would be highly desirable. To test whether regenerating gene (REG) I expression enhances chemo‐ and radiosensitivity in esophageal squamous cell carcinoma cells, we used MTT (3‐[4,5‐dimethylthiazol‐2‐yl]‐2,5‐diphenyltetrazolium bromide) assays to compare the chemo‐ and radiosensitivities of untransfected TE‐5 and TE‐9 cells with those of cells stably transfected with REG Iα and Iβ. We then used flow cytometry to determine whether REG I expression alters cell cycle progression. No REG I mRNA or protein were detected in untransfected TE‐5 and TE‐9 cells. Transfection with REG Iα and Iβ led to strong expression of both REG I mRNA and protein in TE‐5 and TE‐9 cells, which in turn led to significant increases in both chemo‐ and radiosensitivity. Cell cycle progression was unaffected by REG I expression. REG I thus appears to enhance the chemo‐ and radiosensitivity of squamous esophageal cancer cells, which suggests that it may be a useful target for improved and more individualized treatments for patients with esophageal squamous cell carcinoma. (Cancer Sci 2008; 99: 2491–2495)

Review of apoptotic and non-apoptotic events in non-ciliated cells of the mammalian oviduct.

Reproductive organs are known to undergo dynamic changes during the oestrus cycle and pregnancy. Cell growth and regeneration of the reproductive tissues are closely correlated with ovarian steroid hormone levels. This review focuses on apoptotic and non-apoptotic degenerative events within oviduct epithelium that occur in a species-, cycle-, and segment-specific manner. Epithelial extrusion of larger cell fragments including nuclei and whole cells is the characteristic feature of non-apoptotic cell loss of non-ciliated cells in large (pig, sheep, goat, cattle) and small animals (dog). This mechanism of epithelial cell loss is most frequently observed in the luteal phase of the oestrus cycle and after progesterone treatment, respectively. Using light- and electron-microscopic techniques, typical apoptotic epithelial cells characterized by extensive nuclear and cytoplasmic fragmentation are found very sporadically in most species. In contrast, oviduct epithelial cells of subhuman primates and cats in part show marked signs of apoptosis, which could be explained by their respective cycle-specific characteristics. Recent investigations using histochemical markers of apoptosis and our own findings in the porcine oviduct suggest that the degenerative process in the mammalian oviduct includes the death of numerous epithelial cells by apoptosis. Advancement in the knowledge of elimination of oviduct epithelial cells is necessary to understand the physiological process of epithelial renewal and pathological processes caused by imbalances between cell renewal and elimination.

Application of spontaneously immortalized odontoblast cells in tooth regeneration

Here, we report on the first attempt to bioengineer tooth using a spontaneously immortalized mesenchymal cell line. To assess the odontogenic potential of this cell line, odontoblast-lineage cells (OLC) were re-associated with competent dental epithelium isolated from E14.5 mice. A novel three-dimensional organ germ culture method was applied to nurture the constructs in vitro. Additionally, recombinants were transplanted under the kidney capsule in host animals for 2 weeks. Transplants developed into tooth tissues in one-third of the cases. OLC-derived GFP-positive cells could be identified in mineralizing tooth germs by immunohistochemistry. OLCs were capable of intercellular and cell-matrix communication, thus they eventually differentiated into functional odontoblasts. In summary, we managed to utilize OLCs for dental mesenchyme substitution in tooth regeneration experiments. Therefore, our spontaneously transformed cell line proved its potential for future complex, tooth developmental and bioengineering studies.

Expression and localization of regenerating gene I in a rat liver regeneration model.

Regenerating gene (Reg) I has been identified as a regenerative/proliferative factor for pancreatic islet cells. We examined Reg I expression in the regenerating liver of a rat model that had been administered 2-acetylaminofluorene and treated with 70% partial hepatectomy (2-AAF/PH model), where hepatocyte and cholangiocyte proliferation was suppressed and the hepatic stem cells and/or hepatic progenitor cells were activated. In a detailed time course study of activation of hepatic stem cells in the 2-AAF/PH model, utilizing immunofluorescence staining with antibodies of Reg I and other cell-type-specific markers, we found that Reg I-expressing cells are present in the bile ductules and increased during regeneration. Reg I-expressing cells were colocalized with CK19, OV6, and AFP. These results demonstrate that Reg I is significantly upregulated in the liver of the 2-AAF/PH rat model, accompanied by the formation of bile ductules during liver regeneration.

Proteomic analysis identifies proteins that continue to grow hepatic stem-like cells without differentiation

To understand the molecular mechanism underlying vigorous proliferative activity of hepatic stem-like (HSL) cells, we performed two-dimensional electrophoresis to identify the proteins statistically more abundant in rapidly growing undifferentiated HSL cells than in sodium butyrate-treated differentiated HSL cells. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry and Mascot search identified 6 proteins including prohibitin, vimentin, ezrin, annexin A3, acidic ribosomal phosphoprotein P0 and Grp75. Prohibitin and vimentin control the mitogen-activated protein (MAP) kinase pathway. Ezrin is phosphorylated by various protein-tyrosine kinases and modulates interactions between cytoskeletal and membrane proteins. Annexin A3 has a role in DNA synthesis. Acidic ribosomal phosphoprotein P0 and Grp75 play in protein synthesis. These results suggest that the proteins related to the MAP kinase cascade had some role in continuous proliferation of HSL cells without differentiation.

Study of Butyrate Signal Transduction Pathways in Rat Hepatic Stem-Like Cells

Short-chain fatty acids (SCFAs), acetate, propionate and butyrate, are the major anions in the lumen of the large intestine. One of the G protein coupled receptors, GPR43, was recently described as a receptor for SCFAs. To understand pharmacological role of butyrate through GPR43, we analyzed cell shape, GPR43 mRNA expression and mitogen-activated protein (MAP) kinase activation in rat hepatic stem-like (HSL) cells. RT-PCR demonstrated that GPR43 mRNA was expressed in HSL cells and the expression level was not affected by butyrate treatment. Western blot analysis revealed that ERK phosphorylation was enhanced 10 min after sodium butyrate treatment then decreased to the initial level after 24 h. In contrast, Ark phosphorylation was not detected. The results obtained were contrary to our intention, because much cell death was observed after sodium butyrate treatment.