Tsutomu Iwamoto

The University of Tokushima, Tokusima, Tokushima, Japan

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Publications (41)92.27 Total impact

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    ABSTRACT: The dental epithelium and extracellular matrix interact to ensure that cell growth and differentiation lead to the formation of teeth of appropriate size and quality. To determine the role of fibronectin in differentiation of the dental epithelium and tooth formation, we analyzed its expression in developing incisors. Fibronectin mRNA was expressed during the presecretory stage in developing dental epithelium, decreased in the secretory and early maturation stages, and then reappeared during the late maturation stage. The binding of dental epithelial cells derived from postnatal day-1 molars to a fibronectin-coated dish was inhibited by the RGD but not RAD peptide, and by a β1 integrin-neutralizing antibody, suggesting that fibronectin-β1 integrin interactions contribute to dental epithelial-cell binding. Because fibronectin and β1 integrin are highly expressed in the dental mesenchyme, it is difficult to determine precisely how their interactions influence dental epithelial differentiation in vivo . Therefore, we analyzed β1 integrin conditional knockout mice ( Intβ1<sup>lox-/lox-</sup>/K14-Cre ) and found that they exhibited partial enamel hypoplasia, and delayed eruption of molars and differentiation of ameloblasts, but not of odontoblasts. Furthermore, a cyst-like structure was observed during late ameloblast maturation. Dental epithelial cells from knockout mice did not bind to fibronectin, and induction of ameloblastin expression in these cells by neurotrophic factor-4 was inhibited by treatment with RGD peptide or a fibronectin siRNA, suggesting that the epithelial interaction between fibronectin and β1 integrin is important for ameloblast differentiation and enamel formation.
    PLoS ONE 04/2015; 10(4-4):e0121667. DOI:10.1371/journal.pone.0121667 · 3.53 Impact Factor
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    ABSTRACT: Canonical Wnt signaling and BMP promote the proliferation and differentiation of osteoprogenitors, respectively. However, the regulatory mechanism involved in the transition from proliferation to differentiation is unclear. Here, we show that pannexin 3 (Panx3) plays a key role in this transition by inhibiting the proliferation and promoting the cell cycle exit. Using primary calvarial cells and explants, C3H10T1/2 cells, and C2C12 cells, we found that Panx3 expression inhibited cell growth, whereas the inhibition of endogenous Panx3 expression increased it. We also found that the Panx3 hemichannel inhibited cell growth by promoting β-catenin degradation through GSK3β activation. Additionally, the Panx3 hemichannel inhibited cyclin D1 transcription and Rb phosphorylation through reduced cAMP/PKA/CREB signaling. Furthermore, the Panx3 endoplasmic reticulum (ER) Ca2+ channel induced the transcription and phosphorylation of p21, through the calmodulin/Smad pathway, and resulted in the cell cycle exit. Our results reveal that Panx3 is a new regulator that promotes the switch from proliferation to differentiation of osteoprogenitors via multiple Panx3 signaling pathways.
    Journal of Biological Chemistry 12/2013; 289(5). DOI:10.1074/jbc.M113.523241 · 4.60 Impact Factor
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    ABSTRACT: Objective: The interactions between the oral epithelium-derived dental epithelium and the underlying neural crest-derived dental mesenchyme regulate tooth development including the determination of tooth size. We found that nerve growth factor (NGF) promotes cell proliferation in dental epithelial cell. However, the mechanism of NGF-induced proliferation of dental epithelial cell is little known. The purpose of this study is to elucidate the roles of NGF in dental epithelial proliferation. Method: Expression of NGF and their receptors, TrkA and p75 in mouse tooth germ were analyzed by RT-PCR and immunostaining. To examine the role of NGF in dental epithelium, we used the dental epithelial cell line, SF2, and constructed the expression vectors for p75 and the deletion mutant of p75 intracellular domain (ΔICD) to establish the stably expressing p75 or ΔICD SF2 cells. Proliferation of these SF2 cells was assessed by cell counting kit, and BrdU incorporation assay. NGF signaling were analyzed by western blotting using antibodies for MAP kinase pathway. Result: RT-PCR analysis reveled that NGF and p75, but not TrkA, were expressed in SF2 cells. p75 was expressed in inner dental epithelial cell of cervical loop in P1 tooth germ. NGF promoted SF2 cells proliferation. Further, proliferation was enhanced in p75 over-expressing SF2 cells. On the other hand, NGF-induced cell proliferative activity was reduced in ΔICD transfected SF2 cells. p75 inhibitor TAT-pep5 was also reduced NGF-induced cell proliferation. Western blotting demonstrated that NGF induced phosphorylations of Src and ERK1/2 in SF2 cells. Conclusion: Our results indicated that NGF induced cell proliferation and activates Src or ERK phosphorylation in SF2 cell via p75, but not TrkA. NGF may be important for the determination of tooth size.
    IADR Asia/Pacific Region (APR) Regional Meeting and Co-Annual Scientific Meeting of IADR Divisions 2013; 08/2013
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    ABSTRACT: Crown discoloration of permanent teeth is caused by trauma, periapical lesions of the deciduous teeth, pharmaceuticals, and systemic diseases. Crown discoloration has been treated with bleaching or crown restoration. However, these methods are not appropriate during the growth and development period of children.In this study, we used BeautiCoat™ (Shofu Inc., Kyoto, Japan), a tooth-surface coating material that contains high levels of controlled-release fluoride, that temporarily improves crown color. We evaluated the effect of the primer on tooth-surface characteristics in addition to the coating agent's shear bond strength, tooth-surface condition, and duration of attachment. Additionally, we surveyed patients' satisfaction with the color improvement.The results showed no adverse effects of the primer on the enamel surface. The coating material itself showed a high degree of shear bond strength. Based on observations of shedding and fracturing in clinical applications, we found that the coating material maintained long-term attachment if applied under conditions of strict moisture prevention and it avoided areas of occlusion. Treated children and their parents were highly satisfied with the color improvement. These results suggest that this coating material is appropriate for improving the color of discolored teeth during childhood.
    04/2013; 23(1):44–50. DOI:10.1016/j.pdj.2013.03.011
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    ABSTRACT: Cell–cell and cell–matrix interactions are essential for cell differentiation, function, and maintenance of skeletal tissue. Gap junction proteins, composed of connexin (Cx) and pannexin (Panx) families, mediate these interactions and play an important role in cell–cell communications. Cx and Panx share similar protein structures, but have evolved differently. The Panx family was initially identified by its sequence homology to the invertebrate gap junction innexin family. The Panx family comprises three members, Panx1, 2, and 3. Panx1 is expressed in many organs, such as the eyes, thyroid, prostate, kidneys, and liver, but its expression is especially strong in the central nervous system. Similarly, Panx2 is expressed mainly in the central nervous system. Panx3 is expressed predominantly in skeletal tissues, including cartilage and bone. In this review, we describe the expression and functions of Cxs and Panx3 in cartilage and bone.
    Journal of Oral Biosciences 02/2013; 55(1):29–33. DOI:10.1016/j.job.2012.12.001
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    ABSTRACT: Objectives: Pannexin 3 (Panx3), a new member of the gap junction family proteins, promotes chondrocytes and osteoblast differentiation. However, the expression and physiological functions of Panx3 in tooth development are not known. Our objectives are to analyze the expression of Panx3 in developing teeth and to characterize the role of Panx3 in odontoblast differentiation. Methods: Northern blotting and in situ hybridization were performed for the expression analysis of Panx3 mRNA in developing teeth. To analyze the functions of Panx3 in odontoblast differentiation, we used the odontoblastic mDP cells and transfected them with a Panx3 expression vector. To knockdown the endogenous Panx3 gene, we used Panx3 siRNA. Cell proliferation was measured by BrdU incorporation assays. Western blotting was performed to analyze BMP signaling. Results: Panx3 mRNA was strongly expressed in preodontoblasts. Expression of Panx3 was progressively induced in differentiating mDP cells after treatment with BMP-2. Panx3-transfected cells reduced BrdU incorporation, indicating that Panx3 inhibited their proliferation. Furthermore, Panx3 promoted the expression of Dspp, a marker of differentiated odontoblasts. Conversely, the suppression of endogenous Panx3 expression by siRNA inhibited the expression of the Dspp gene and BMP-2 induced phosphorylation of Smad1/5/8. Conclusion: Our results indicate that Panx3 inhibits odontoblastic cell proliferation and promotes differentiation, suggesting that Panx3 plays an important role in odontoblast differentiation.
    IADR General Session 2012; 06/2012
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    ABSTRACT: Epithelial-mesenchymal interactions regulate the growth and morphogenesis of ectodermal organs such as teeth. Dental pulp stem cells (DPSCs) are a part of dental mesenchyme, derived from the cranial neural crest, and differentiate into dentin forming odontoblasts. However, the interactions between DPSCs and epithelium have not been clearly elucidated. In this study, we established a mouse dental pulp stem cell line (SP) comprised of enriched side population cells that displayed a multipotent capacity to differentiate into odontogenic, osteogenic, adipogenic, and neurogenic cells. We also analyzed the interactions between SP cells and cells from the rat dental epithelial SF2 line. When cultured with SF2 cells, SP cells differentiated into odontoblasts that expressed dentin sialophosphoprotein. This differentiation was regulated by BMP2 and BMP4, and inhibited by the BMP antagonist Noggin. We also found that mouse iPS cells cultured with mitomycin C-treated SF2-24 cells displayed an epithelial cell-like morphology. Those cells expressed the epithelial cell markers p63 and cytokeratin-14, and the ameloblast markers ameloblastin and enamelin, whereas they did not express the endodermal cell marker Gata6 or mesodermal cell marker brachyury. This is the first report of differentiation of iPS cells into ameloblasts via interactions with dental epithelium. Co-culturing with dental epithelial cells appears to induce stem cell differentiation that favors an odontogenic cell fate, which may be a useful approach for tooth bioengineering strategies.
    Journal of Biological Chemistry 02/2012; 287(13):10590-601. DOI:10.1074/jbc.M111.285874 · 4.60 Impact Factor
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    ABSTRACT: Neurotrophin 4 (NT-4) and its receptors regulate the differentiation of ameloblasts in tooth development. Gangliosides, sialic acids that contain glycosphingolipids (GSLs), are involved in a variety of membrane-associated cell physiological functions such as ligand-receptor signal transmission. However, the expression patterns and functions of GSLs during tooth development remain unclear. In this study, we identified strong expressions of GM3 and LacCer in dental epithelium, which give rise to differentiation into enamel-secreting ameloblasts. Exogenous GM3 and LacCer in dental epithelial cells induced the expression of ameloblastin (Ambn), while it was also interesting that GM3 synergistically exerted enhancement of NT-4-mediated Ambn expression. In addition, consistently exogenous GM3 and LacCer in dental epithelial cells induced distinct activation of extracellular signal-regulated kinase 1/2 (ERK1/2), an event upstream of the expression of Ambn. Furthermore, depletion of GSLs from dental epithelial cells by D-threo-1-phenyl-2-decanoylamino-3-morpholino-1-propanol (D-PDMP) inhibited Ambn expression as well as phosphorylation of ERK1/2. In contrast, exogenous addition of GM3 or LacCer rescued the phosphorylation of ERK1/2 repressed by pre-treatment with D-PDMP. Taken together, these results suggest that GM3 and LacCer are essential for NT-4-mediated Ambn expression, and contribute to dental epithelial cell differentiation into ameloblasts.
    Journal of dental research 01/2012; 91(1):78-83. DOI:10.1177/0022034511424408 · 4.14 Impact Factor
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    ABSTRACT: Aim Fluoride, well known as a specific and effective caries prophylactic agent, also affects the differentiation and function of ameloblasts. High dose sodium fluoride (NaF) induces enamel hypoplasia, also called enamel fluorosis, whereas the size and form of teeth except the enamel are not changed with its treatment. We examined the effects of fluoride on dental epithelium proliferation and differentiation using co-cultures of dental epithelial and mesenchymal cells. Methods Cultures of the dental epithelial cell line SF2 and dental mesenchymal cell line mDP were performed, as well as co-cultures. Enamel matrix expression in SF2 cells treated with NaF was analyzed by RT-PCR, while cell proliferation was examined using a trypan blue dye exclusion method and BrdU incorporation findings. The effects of NaF on NT-4-induced ERK1/2 phosphorylation were analyzed by western immunoblotting. Results Neurotrophic factor NT-4 induced enamel matrix expression, which was inhibited in the presence of NaF. Similar results were observed in regard to SF2 cell proliferation, but not with mDP cells. The levels of proliferation and ameloblastin expression in SF2-GFP cells co-cultured with mDP in the presence of NaF were lower as compared to those in SF2 cells cultured alone. Conclusion Our results indicate that dental epithelial cells co-cultured with dental mesenchymal cells are resistant to the inhibitory effects of NaF on proliferation and ameloblastin expression. They also suggest that the dental fluorosis phenotype may affect enamel, but not tooth size or shape, because of rescue of the inhibitory effects of NaF by culturing with dental mesenchymal cells.
    01/2012; 22(1):55–63. DOI:10.1016/S0917-2394(12)70253-7
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    ABSTRACT: The pannexin proteins represent a new gap junction family. However, the cellular functions of pannexins remain largely unknown. Here, we demonstrate that pannexin 3 (Panx3) promotes differentiation of osteoblasts and ex vivo growth of metatarsals. Panx3 expression was induced during osteogenic differentiation of C2C12 cells and primary calvarial cells, and suppression of this endogenous expression inhibited differentiation. Panx3 functioned as a unique Ca(2+) channel in the endoplasmic reticulum (ER), which was activated by purinergic receptor/phosphoinositide 3-kinase (PI3K)/Akt signaling, followed by activation of calmodulin signaling for differentiation. Panx3 also formed hemichannels that allowed release of ATP into the extracellular space and activation of purinergic receptors with the subsequent activation of PI3K-Akt signaling. Panx3 also formed gap junctions and propagated Ca(2+) waves between cells. Blocking the Panx3 Ca(2+) channel and gap junction activities inhibited osteoblast differentiation. Thus, Panx3 appears to be a new regulator that promotes osteoblast differentiation by functioning as an ER Ca(2+) channel and a hemichannel, and by forming gap junctions.
    The Journal of Cell Biology 06/2011; 193(7):1257-74. DOI:10.1083/jcb.201101050 · 9.69 Impact Factor
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    ABSTRACT: Objectives: Platelet-derived growth factors (PDGFs) are known as paracrine growth factors that mediate epithelial-mesenchymal interactions in organogenesis. Further, PDGFα receptor is a marker of neural crest derived cells. However, the role of PDGFs during tooth development has not been clearly understood. Our objects in this study focused on the identification of the molecular mechanism of PDGFs on ameloblast differentiation and odontoblast proliferation. Methods: To analyze the role of PDGFs in tooth development, we used a molar organ culture system and two kinds of cell lines, ameloblastic and odontoblastic cell lines, with or without AG17, an inhibitor of PDGFRα and PDGFRβ signaling. Results: AG17 suppressed both growth and cusp formation in molar tooth germ organ culture. The numbers of BrdU-positive cells were decreased in both dental epithelium and mesenchyme. PDGF-BB promoted proliferation of odontoblastic cells, whereas PDGF-AA did not. Further, PDGF-AA, but not -BB promoted the ameloblastin expression in ameloblastic cells though the phosphorylation of ERK1/2. Conclusion: Our results indicate that PDGFs signaling is important for dental-epithelial and mesenchymal cell proliferation and ameloblast differentiation, suggesting that PDGFs regulate tooth morphogenesis.
    IADR General Session 2011; 03/2011
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    ABSTRACT: Objectives: Pannexin 3 (Panx3) is a new member of the gap junction protein family. The expression and physiological function of Panx3 in teeth are unknown. Our objectives are to analyze the expression of Panx3 in developing teeth and to identify the role of Panx3 in odontoblast differentiation. Methods: Northern blotting and in situ hybridization were performed for expression analysis of Panx3 mRNA in developing teeth. To analyze the function of Panx3 in odontoblast differentiation, we used odontoblastic cell lines. We created Panx3 overexpressed cell lines by stable transfection of a Panx3 expression vector. To suppress endogenous Panx3 expression, we used Panx3 siRNA. Cell proliferation was measured by BrdU incorporation assay, and Western blotting was performed to analyze BMP signaling. Results: Panx3 mRNA was strongly expressed in preodontoblasts of developing teeth, and expression of Panx3 was progressively induced during differentiation of odontoblastic cells in the presence of BMP-2. Panx3 overexpression inhibited BrdU incorporation, indicating that Panx3 inhibited cell proliferation. Further, Panx3 overexpression promoted the expression of DSPP, a marker of differentiated odontoblasts. Conversely, suppression of endogenous Panx3 by siRNA inhibited the expression of DSPP, and BMP-2 induced phosphorylation of Smad1/5/8. Conclusion: Our results indicate that Panx3 inhibits odontoblastic cell proliferation and promotes differentiation, thus suggesting that Panx3 plays an important role in odontoblast differentiation. (Supported in part from the Intramural Research Program of the National Institute of Dental and Craniofacial Research, NIH (DE000720-04).)
    IADR General Session 2011; 03/2011
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    ABSTRACT: Neurotrophic factors are soluble growth factors predominantly expressed in vertebrate nervous systems and have been well-characterized for their critical roles in neural tissues. Recent studies have revealed that neurotrophin factors and their receptors are also expressed in multiple non-neural tissues, and play a role in a wide range of biological functions, such as regulation of cellular proliferation, survival, migration, and differentiation. The neurotrophic factor family is defined by its structural and functional similarities to 4 ligands; nerve growth factor (NGF), brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT-3), and neurotrophin-4 (NT-4, also known as NT-5). They activate 2 different receptors, trk tyrosine kinase and p75, the latter of which is a member of the tumor necrosis factor receptor superfamily. During tooth development, observations of dynamic changes of specific expression patterns of neurotrophic factors and their receptors imply their important functions in odontogenic processes. In addition, our recent study demonstrated that NT-4 regulates proliferation and differentiation of dental epithelium, and promotes the production of enamel matrixes. In this review, we describe the expression patterns and functions of neurotrophic factors in the tooth germ, and discuss the relationships with tooth development.
    Journal of Oral Biosciences 01/2011; 53(1):13–21. DOI:10.1016/S1349-0079(11)80031-9
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    ABSTRACT: Objectives: New one-step self-etching adhesive system (BeautiBond), which are HEMA-free and used unique dual adhesive monomers, delivers equal bond strength to both enamel and dentin. The advantages of this adhesive system are easy usage and short operation time. However, it has been reported that one-step adhesive systems is poor adhesive strength as compared with conventional two-step adhesive systems. In this study, we evaluated clinical application of this adhesive system as compared with conventional two-step adhesive system. Methods: The subjects of this study ware 35 patients who regularly visited pediatric dentistry of Tohoku University Hospital and had been treated of dental caries in primary or permanent teeth with resin restoration. BeautiBond (new one-step system, Shofu) and Mega Bond (two-step system, Kuraray) were applied for treatment of 36 teeth and 51 teeth, respectively. Applied resin composites using in this study are Beautifil Flow F02 (Shofu), Clearfil AP-X (kuraray) , Beautifil II(Shofu), clearfil Majesty (kuraray) or MI flow (GC). No consideration was give to patient's parafunctional habits and caries risk. We examined condition of resin restoration for detachment, marginal fracture, marginal adaptation, and marginal discoloration using modified Ryge criteria. Results: Average of observation period after cavity restoration was 16 months. BeautiBond group showed 2 cases of unacceptable margin. Mega Bond group showed 3 cases of unacceptable margin and 1 case of marginal discoloration. The frequency of unacceptable margin and marginal discoloration was not statistically different between BeautiBond and Mega Bond. Conclusion: BeautiBond, one-step adhesive system provided excellent clinical performance, similar to two-step adhesive system, indicating that BeautiBond is useful adhesive system for restoration of primary teeth and permanent teeth in pediatric dentistry.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Branching morphogenesis of salivary gland is regulated by sequential and reciprocal interactions between oral ectoderm and mesenchyme. Recently, we reported that PDGF signal is one of regulators in branching morphogenesis by modulating this interaction. Exogenous administration of PDGF in organ culture of salivary glands enhanced branching via mesenchymal FGF expression. Gja1, encoding one of gap junctional proteins, regulates cell-cell communication and involved in tissue organization. However, it has not been cleared the role of gap junction during salivary gland development. Here, we analyzed the interaction between PDGF signaling and gap junction during branching morphogenesis using organ culture system. Methods: Gja1-null salivary gland was stained with H-E and analyzed by histologically. Submandibular glands (SMGs) from dissected embryonic 13 mice were cultured on Cell Culture Insert™ track-etched filters (0.4 mm pore size). Exogenous 10 ng/ml of PDGF-BB or 1 mg/ml of FGF10 was added to the culture medium with or without gap junctional inhibitor 18a -GA, and photographed SMGs at 2, 24 and 48 hours. The numbers of terminal buds at 24h and 48h were compared with those at 2h. ERK1/2 phosphorylation was analyzed by western immunoblotting. Results: Gja1-null mice showed defective branching morphogenesis in salivary gland indicating that cell-cell communication is important for branching morphogenesis. Gap junctional inhibitor 18a-GA inhibited branching morphogenesis of SMGs. In contrast, exogenous addition of PDGF had accelerated branching. Furthermore, exogenous PDGF and FGF10 partially rescued branching of SMGs inhibited by 18a-GA. In addition, exogenous FGF10 partilly rescued phosphorylation of ERK1/2 inhibited by 18a-GA. Conclusion: Epithelial-mesenchymal interaction of SMGs was regulated by gap junction, especially Gja1, indicating that gap junctional communication is necessary for branching morphogenesis and may regulate PDGF-FGF signaling.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Dental pulp cells are suitable for tissue regeneration. However, the concentration of stem cells in dental tissue is less than 1% of total dental pulp cells. This observation shows a limitation of the application of dental pulp stem cells for clinical purpose. Recent reports shows that Wnt/beta-catenin signaling is important for maintaining of stem cells. Wnt/beta-catenin signaling regulated by intracellular signaling molecules, axin, APC and GSK-3beta. Beta-catenin was phosphorylated and negatively regulated the translocation into nucleus by GSK-3beta. In this study, we tried to generate stem cells from differentiated dental pulp cell using chemical compound, especially GSK-3beta inhibitor. Methods: To isolate side population (SP) and major population (MP) cells, mouse dental pulp cell line mDP were sorted by flow-cytometory using Hoechist dye staining. Cell shapes of SP, MP and mDP cells with or without GSK-3beta inhibitor were examined using phalloidin-Alexa fluor 594 staining. Expression of Oct4 and Nanog, markers of stem cells, was analyzed by RT-PCR. Proliferation of cells was examined at 1, 3 and 5 days after addition of GSK-3beta inhibitor. Results: Differentiated dental pulp cells were mixed cell populations and showed elongated cell shapes. mDP and MP cells did not express Oct4 and Nanog. GSK3beta inhibitor treated mDP cells showed spindle shape as similar to SP cells. Proliferation of these cells was decreased compared to non-treated cells. Further, cells expressed Oct4 and Nanog after treatment with GSK-3beta inhibitor, indicating that this chemical compound promotes reprogramming of dental pulp cells. Conclusions: GSK-3beta inhibitor induced the expression of Oct4 and Nanog, and promoted reprogramming of differentiated dental pulp cells into dental pulp stem cells. This chemical compound may be useful for therapeutic reagent for dental tissue regeneration.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objective: Tooth morphogenesis with functional shape and proper size is characterized by sequential epithelial-mesenchymal interactions. However, It is still not fully understood the regulation of tooth development and morphogenesis, especially ameloblast differentiation and enamel formation. The induced pluripotent stem (iPS) cell, a reprogramming somatic cell with nuclear reprogramming factors, would be expected for use in tissue engineering. Here, we demonstrate the in vitro ameloblast differentiation system from iPS cells to analyze the ameloblast differentiation. Materials and Methods: We used rat dental epithelium cell line, SF2 cells, as feeder cells for mouse iPS cells culture. Differentiation of ameloblast was analyzed by RT-PCR using mouse ameloblastin (Ambn) locked nucleic acid (LNA) primer sets to bind complementary nucleic acid with higher affinity and specificity. Results: The species specific LNA primers for Ambn gene in both mouse and rat were designed and the specificity of those primer sets were confirmed by RT-PCR using mouse or rat tooth germ cDNAs. Mouse iPS cells were cultured on rat SF2 feeder cells that were pretreated with mitomycin C led to arrest cell replication. After 7 days, some of iPS cells showed polygonal cell-shape similar to epithelial cells. In addition, RT-PCR analysis showed obvious expression of Ambn in iPS cells. Taken together these results indicate that iPS cells were induced to differentiate into ameloblasts and suggested that the cell fate of iPS cells were directed and induced by the ameloblastic local microenvironment. Conclusion: Our pioneering research provides that iPS cells could differentiate into ameloblasts by co-culture with dental epithelial cells. This culture system can be useful to analyze the molecular mechanism of ameloblast differentiation and utilized the regeneration of other cell types by controlling a local microenvironment surrounding iPS cell.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Pannexin 3 (Panx3) is a new member of the gap junction pannexin family, but its expression profiles and physiological function are not yet clear. We demonstrate in this study that Panx3 is expressed in cartilage and regulates chondrocyte proliferation and differentiation. Panx3 mRNA was expressed in the prehypertrophic zone in the developing growth plate and was induced during the differentiation of chondrogenic ATDC5 and N1511 cells. Panx3-transfected ATDC5 and N1511 cells promoted chondrogenic differentiation, but the suppression of endogenous Panx3 inhibited differentiation of ATDC5 cells and primary chondrocytes. Panx3-transfected ATDC5 cells reduced parathyroid hormone-induced cell proliferation and promoted the release of ATP into the extracellular space, possibly by action of Panx3 as a hemichannel. Panx3 expression in ATDC5 cells reduced intracellular cAMP levels and the activation of cAMP-response element-binding, a protein kinase A downstream effector. These Panx3 activities were blocked by anti-Panx3 antibody. Our results suggest that Panx3 functions to switch the chondrocyte cell fate from proliferation to differentiation by regulating the intracellular ATP/cAMP levels.
    Journal of Biological Chemistry 06/2010; 285(24):18948-58. DOI:10.1074/jbc.M110.127027 · 4.60 Impact Factor
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    ABSTRACT: Pannexin 3 (Panx3) is a new member of the gap junction pannexin family, but its expression profiles and physiological function are not yet clear. We demonstrate in this study that Panx3 is expressed in cartilage and regulates chondrocyte proliferation and differentiation. Panx3 mRNA was expressed in the prehypertrophic zone in the developing growth plate and was induced during the differentiation of chondrogenic ATDC5 and N1511 cells. Panx3-transfected ATDC5 and N1511 cells promoted chondrogenic differentiation, but the suppression of endogenous Panx3 inhibited differentiation of ATDC5 cells and primary chondrocytes. Panx3-transfected ATDC5 cells reduced parathyroid hormone-induced cell proliferation and promoted the release of ATP into the extracellular space, possibly by action of Panx3 as a hemichannel. Panx3 expression in ATDC5 cells reduced intracellular cAMP levels and the activation of cAMP-response element-binding, a protein kinase A downstream effector. These Panx3 activities were blocked by anti-Panx3 antibody. Our results suggest that Panx3 functions to switch the chondrocyte cell fate from proliferation to differentiation by regulating the intracellular ATP/cAMP levels.
    Journal of Biological Chemistry 06/2010; 285(24):18948-18958. · 4.60 Impact Factor
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    ABSTRACT: The purpose of this study was to elucidate the effects of platelet-derived growth factors (PDGFs) during tooth development, as well as the mechanisms underlying the interactions of growth factors with PDGF signalling during odontogenesis. We used an ex vivo tooth germ organ culture system and two dental cell lines, SF2 cells and mDP cells, as models of odontogenesis. AG17, a tyrosine kinase inhibitor, was utilised for blocking PDGF receptor signalling. To analyse the expressions of PDGFs, reverse transcriptase (RT)-PCR and immunohistochemistry were performed. Proliferation was examined using a BrdU incorporation assay for the organ cultures and a cell counting kit for the cell lines. The expressions of Fgf2 and ameloblastin were analysed by real-time RT-PCR. The PDGF ligands PDGF-A and PDGF-B, and their receptors, PDGFRalpha and PDGFRbeta, were expressed throughout the initial stages of tooth development. In the tooth germ organ cultures, PDGF-AA, but not PDGF-BB, accelerated cusp formation. Conversely, AG17 suppressed both growth and cusp formation of tooth germs. Exogenous PDGF-BB promoted mDP cell proliferation. Furthermore, PDGF-AA decreased Fgf2 expression and increased that of ameloblastin, a marker of differentiated ameloblasts. Our results indicate that PDGFs are involved in initial tooth development and regulate tooth size and shape, as well as ameloblast differentiation.
    Archives of oral biology 04/2010; 55(6):426-34. DOI:10.1016/j.archoralbio.2010.03.011 · 1.88 Impact Factor

Publication Stats

604 Citations
92.27 Total Impact Points

Institutions

  • 2013
    • The University of Tokushima
      • Department of Pediatrics
      Tokusima, Tokushima, Japan
  • 2009–2012
    • Tohoku University
      • Department of Pediatrics
      Japan
  • 2007–2011
    • National Institutes of Health
      • Laboratory of Cell and Developmental Biology
      Bethesda, MD, United States
  • 2007–2009
    • Kyushu University
      • Faculty of Dental Science
      Fukuoka-shi, Fukuoka-ken, Japan
  • 2001
    • Hokkaido University
      • Graduate School of Pharmaceutical Sciences
      Sapporo-shi, Hokkaido, Japan