Tetsuya Taga

Publications (45)180.37 Total impact

• Article: CD45(low)c-Kit(high) cells have hematopoietic properties in the mouse aorta-gonad-mesonephros region.

  Ikuo Nobuhisa, Shoutarou Yamasaki, Ahmed Ramadan, Tetsuya Taga
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  ABSTRACT: Long-term reconstituting hematopoietic stem cells first arise from the aorta of the aorta-gonad-mesonephros (AGM) region in a mouse embryo. We have previously reported that in cultures of the dispersed AGM region, CD45(low)c-Kit(+) cells possess the ability to reconstitute multilineage hematopoietic cells, but investigations are needed to show that this is not a cultured artifact and to clarify when and how this population is present. Based on the expression profile of CD45 and c-Kit in freshly dissociated AGM cells from embryonic day 9.5 (E9.5) to E12.5 and aorta cells in the AGM from E13.5 to E15.5, we defined six cell populations (CD45(-)c-Kit(-), CD45(-)c-Kit(low), CD45(-)c-Kit(high), CD45(low)c-Kit(high), CD45(high)c-Kit(high), and CD45(high)c-Kit(very low)). Among these six populations, CD45(low)c-Kit(high) cells were most able to form hematopoietic cell colonies, but their ability decreased after E11.5 and was undetectable at E13.5 and later. The CD45(low)c-Kit(high) cells showed multipotency in vitro. We demonstrated further enrichment of hematopoietic activity in the Hoechst dye-effluxing side population among the CD45(low)c-Kit(high) cells. Here, we determined that CD45(low)c-Kit(high) cells arise from the lateral plate mesoderm using embryonic stem cell-derived differentiation system. In conclusion, CD45(low)c-Kit(high) cells are the major hematopoietic cells of mouse AGM.
  Experimental Cell Research 04/2012; 318(6):705-15. · 3.58 Impact Factor
• Article: Identification of a yolk sac cell population with hematopoietic activity in view of CD45/c-Kit expression.

  Shoutarou Yamasaki, Ikuo Nobuhisa, Ahmed Ramadan, Tetsuya Taga
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  ABSTRACT: During murine embryonic development, primitive hematopoiesis occurs in the yolk sac (YS). Recent studies have shown that the YS also harbors definitive hematopoietic activity. However, the population of YS cells contributing to definitive hematopoiesis has not been identified. In this study, we characterized the hematopoietic cell populations in the YS of mouse embryos from E9.5 to E14.5 in view of the expression profiles of CD45 and c-Kit. The YS cells from E9.5 to E11.5 could be divided into six populations: CD45(-) c-Kit(-) , CD45(-) c-Kit(low) , CD45(-) c-Kit(high) , CD45(low) c-Kit(high) , CD45(high) c-Kit(high) and CD45(high) c-Kit(very low) . Among these populations, CD45(low) c-Kit(high) cells showed the highest multilineage hematopoietic colony-forming activity. Later in development, the YS cells from E12.5 to E14.5 lost the second and fourth populations (i.e., they retained CD45(-) c-Kit(-) , CD45(-) c-Kit(high) , CD45(high) c-Kit(high) and CD45(high) c-Kit(very low) cells), and concurrently with the disappearance of the CD45(low) c-Kit(high) population, no significant hematopoietic activity was found in any of the populations on and after E12.5. CD45(low) c-Kit(high) YS cells, which had a round morphology with a large nucleus, possessed the ability to differentiate into myeloid and B lymphoid cells when cultured with stromal cells. These findings suggest that CD45(low) c-Kit(high) YS cells include more undifferentiated cells than the other YS cell populations and possess in vitro potency to differentiate into multilineage hematopoietic cells. Furthermore, this cell population disappears from the YS at around E12.5, when the site of hematopoiesis has already shifted to the fetal liver and the placenta.
  Embryologia 08/2011; 53(7):870-7. · 2.21 Impact Factor
• Article: Wnt3a promotes hippocampal neurogenesis by shortening cell cycle duration of neural progenitor cells.

  Yutaka Yoshinaga, Tetsushi Kagawa, Takeshi Shimizu, Toshihiro Inoue, Shinji Takada, Jun-ichi Kuratsu, Tetsuya Taga
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  ABSTRACT: The effects of Wnt signaling on neural progenitor cells have been controversial. Activation of the canonical Wnt signaling pathway either promotes neural progenitor cell proliferation or accelerates their differentiation into postmitotic neurons. This study demonstrates that activation of the Wnt signaling pathway by itself induces neural progenitor cell proliferation but does not directly affect neuronal differentiation processes. To investigate whether Wnt signaling promotes expansion and/or differentiation of neural progenitor cells in the developing hippocampus, we prepared primary mouse hippocampal progenitors and treated them with Wnt3a in a chemically defined culture medium. Wnt3a increased the total number of cells, including the numbers of Ki67(+) proliferating cells and Tuj1(+) differentiated neurons. This result verified that Wnt3a promoted neural progenitor cell proliferation. Meanwhile, Wnt3a did not appear to actively enhance the neuronal differentiation process itself, because (1) the ratio of Tuj1(+) cells to the total cells, and (2) the ratio of BrdU(+) Tuj1(+) cells to the total BrdU(+) cells, were both comparable between cultures with or without Wnt3a. Indeed, Wnt3a caused no significant change in either cell survival or the proportion of symmetric and asymmetric cell divisions that directly affected neuron production. We finally demonstrated that the Wnt3a treatment simply shortened cell cycle duration of neural progenitor cells by 2.9 h. The accelerated cell cycle progression without affecting the ratio of symmetric/asymmetric cell divisions explains how Wnt signaling per se leads to the expansion of both proliferative cell population and differentiated neuronal cell population.
  Cellular and Molecular Neurobiology 10/2010; 30(7):1049-58. · 1.97 Impact Factor
• Article: Cells with hematopoietic activity in the mouse placenta reside in side population.

  Ahmed Ramadan, Ikuo Nobuhisa, Shoutarou Yamasaki, Naomi Nakagata, Tetsuya Taga
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  ABSTRACT: The discovery of a major hematopoietic stem cell pool in midgestation mouse embryo has defined the placenta as an important hematopoietic anatomical site. In this study, we examined the flow cytometric pattern of mouse placenta cells on embryonic days (E) 10.5 to E15.5, in view of CD45 and c-Kit expression. We also determined which population of these cells shows differentiation potential toward multiple hematopoietic lineages by performing coculture with OP9 stromal cells and colony-forming assay in methylcellulose. Only CD45(+)c-Kit(+) population showed the ability to form hematopoietic colonies including multiple lineages. To distinguish which fraction of placenta cells have the hematopoietic activity, we used GFP transgenic mice in which the fetal part of the placenta is GFP positive and the maternal part is GFP negative. E11.5 and E13.5 CD45(+)c-Kit(+) placental cells that have ability to form hematopoietic colonies are the fetal GFP positive placental cells. E11.5 and E13.5 CD45(+)c-Kit(+) placental cells that have an ability to form hematopoietic colonies mainly reside in Hoechst dye-effluxing side population area (SP). Taken together, in the placenta of mouse embryo, we conclude that SP cells in the CD45(+)c-Kit(+) fetal placental cells have the ability to form hematopoietic colonies.
  Genes to Cells 09/2010; 15(9):983-94. · 2.68 Impact Factor
• Article: Involvement of the Hipk family in regulation of eyeball size, lens formation and retinal morphogenesis.

  Toshihiro Inoue, Tetsushi Kagawa, Miyuki Inoue-Mochita, Kyoichi Isono, Naoki Ohtsu, Ikuo Nobuhisa, Mikiko Fukushima, Hidenobu Tanihara, Tetsuya Taga
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  ABSTRACT: Members of the homeodomain-interacting protein kinase (HIPK) family are involved in various intracellular regulatory mechanisms. The present study focused on clarifying the functions of HIPK family members in ocular organization during late embryogenesis. HIPK1 and HIPK2 were expressed in the inner retina during late embryogenesis. Hipk1(+/-)Hipk2(-/-) mice had a greater frequency of small eyes with a lens deficiency and abnormally laminated and thickened retinas than did wild-type littermates. These data indicate that Hipk1 and Hipk2 are involved in regulation of eye size, lens formation and retinal lamination during late embryogenesis.
  FEBS letters 07/2010; 584(14):3233-8. · 3.54 Impact Factor
• Source

  Available from: sissa.it

  Article: Committed neuronal precursors confer astrocytic potential on residual neural precursor cells.

  Masakazu Namihira, Jun Kohyama, Katsunori Semi, Tsukasa Sanosaka, Benjamin Deneen, Tetsuya Taga, Kinichi Nakashima
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  ABSTRACT: During midgestation, mammalian neural precursor cells (NPCs) differentiate only into neurons. Generation of astrocytes is prevented at this stage, because astrocyte-specific gene promoters are methylated. How the subsequent switch from suppression to expression of astrocytic genes occurs is unknown. We show in this study that Notch ligands are expressed on committed neuronal precursors and young neurons in mid-gestational telencephalon, and that neighboring Notch-activated NPCs acquire the potential to become astrocytes. Activation of the Notch signaling pathway in midgestational NPCs induces expression of the transcription factor nuclear factor I, which binds to astrocytic gene promoters, resulting in demethylation of astrocyte-specific genes. These findings provide a mechanistic explanation for why neurons come first: committed neuronal precursors and young neurons potentiate remaining NPCs to differentiate into the next cell lineage, astrocytes.
  Developmental cell 03/2009; 16(2):245-55. · 13.36 Impact Factor
• Article: Stabilized beta-catenin functions through TCF/LEF proteins and the Notch/RBP-Jkappa complex to promote proliferation and suppress differentiation of neural precursor cells.

  Takeshi Shimizu, Tetsushi Kagawa, Toshihiro Inoue, Aya Nonaka, Shinji Takada, Hiroyuki Aburatani, Tetsuya Taga
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  ABSTRACT: The proliferation and differentiation of neural precursor cells are mutually exclusive during brain development. Despite its importance for precursor cell self renewal, the molecular linkage between these two events has remained unclear. Fibroblast growth factor 2 (FGF2) promotes neural precursor cell proliferation and concurrently inhibits their differentiation, suggesting a cross talk between proliferation and differentiation signaling pathways downstream of the FGF receptor. We demonstrate that FGF2 signaling through phosphatidylinositol 3 kinase activation inactivates glycogen synthase kinase 3beta (GSK3beta) and leads to the accumulation of beta-catenin in a manner different from that in the Wnt canonical pathway. The nuclear accumulated beta-catenin leads to cell proliferation by activating LEF/TCF transcription factors and concurrently inhibits neuronal differentiation by potentiating the Notch1-RBP-Jkappa signaling pathway. beta-Catenin and the Notch1 intracellular domain form a molecular complex with the promoter region of the antineurogenic hes1 gene, allowing its expression. This signaling interplay is especially essential for neural stem cell maintenance, since the misexpression of dominant-active GSK3beta completely inhibits the self renewal of neurosphere-forming stem cells and prompts their neuronal differentiation. Thus, the GSK3beta/beta-catenin signaling axis regulated by FGF and Wnt signals plays a pivotal role in the maintenance of neural stem/precursor cells by linking the cell proliferation to the inhibition of differentiation.
  Molecular and cellular biology 11/2008; 28(24):7427-41. · 6.06 Impact Factor
• Article: Media conditioned by retinal pigment epithelial cells suppress the canonical Wnt pathway.

  Toshihiro Inoue, Takahiro Kawaji, Miyuki Inoue-Mochita, Tetsuya Taga, Hidenobu Tanihara
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  ABSTRACT: Retinal pigment epithelial (RPE) cells play critical roles in the maintenance of visual function, partly by secreting various biologically active factors that modulate the intraocular environment. Recent studies suggest involvement of Wnt proteins secreted by RPE cells in the pathogenesis of photoreceptor degeneration. In the present study, we examined, via the luciferase assay, the effect of media conditioned by RPE cells (RPE-CM) on activity of the canonical Wnt pathway in vitro. We isolated primary RPE cells from Long-Evans rats at P6-P9. In culture, these cells formed a monolayer with polygonal cell morphology and demonstrated repigmentation at confluency and immunoreactivity for ZO-1, a marker for tight junctions. To evaluate the effect of RPE-CM on the canonical Wnt pathway, we replaced the culture media of COS-7 cells transfected with (Tcf)(7)LUC, a multimeric Tcf-responsive element luciferase reporter construct, with RPE-CM and measured luciferase activity with or without Wnt3a or SB216763, a specific GSK3 inhibitor. RPE-CM did not enhance basal or Wnt3a-induced (Tcf)(7)LUC activity; instead, this activity decreased by 60%. RPE-CM also reduced SB216763-induced (Tcf)(7)LUC activity by 65%, which suggests that the inhibitory effect of RPE-CM is probably due to intracellular crosstalk rather than extracellular antagonism. RPE cells may thus be able to modulate the intraocular environment by regulating the canonical Wnt pathway.
  Neuroscience Letters 10/2007; 424(3):190-3. · 2.11 Impact Factor
• Article: Potentiation of astrogliogenesis by STAT3-mediated activation of bone morphogenetic protein-Smad signaling in neural stem cells.

  Shinji Fukuda, Masahiko Abematsu, Hiroyuki Mori, Makoto Yanagisawa, Tetsushi Kagawa, Kinichi Nakashima, Akihiko Yoshimura, Tetsuya Taga
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  ABSTRACT: Astrocytes play important roles in brain development and injury response. Transcription factors STAT3 and Smad1, activated by leukemia inhibitory factor (LIF) and bone morphogenetic protein 2 (BMP2), respectively, form a complex with the coactivator p300 to synergistically induce astrocytes from neuroepithelial cells (NECs) (K. Nakashima, M. Yanagisawa, H. Arakawa, N. Kimura, T. Hisatsune, M. Kawabata, K. Miyazono, and T. Taga, Science 284:479-482, 1999). However, the mechanisms that govern astrogliogenesis during the determination of the fate of neural stem cells remain elusive. Here we found that LIF induces expression of BMP2 via STAT3 activation and leads to the consequent activation of Smad1 to efficiently promote astrogliogenic differentiation of NECs. The BMP antagonist Noggin abrogated LIF-induced Smad1 activation and astrogliogenesis by inhibiting BMPs produced by NECs. NECs deficient in suppressor of cytokine signaling 3 (SOCS3), a negative regulator of STAT3, readily differentiated into astrocytes upon activation by LIF not only due to sustained activation of STAT3 but also because of the consequent activation of Smad1. Our study suggests a novel LIF-triggered positive regulatory loop that enhances astrogliogenesis.
  Molecular and Cellular Biology 08/2007; 27(13):4931-7. · 5.53 Impact Factor
• Article: Identification of a population of cells with hematopoietic stem cell properties in mouse aorta-gonad-mesonephros cultures.

  Ikuo Nobuhisa, Naoki Ohtsu, Seiji Okada, Naomi Nakagata, Tetsuya Taga
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  ABSTRACT: The aorta-gonad-mesonephros (AGM) region is a primary source of definitive hematopoietic cells in the midgestation mouse embryo. In cultures of dispersed AGM regions, adherent cells containing endothelial cells are observed first, and then non-adherent hematopoietic cells are produced. Here we report on the characterization of hematopoietic cells that emerge in the AGM culture. Based on the expression profiles of CD45 and c-Kit, we defined three cell populations: CD45(low) c-Kit(+) cells that had the ability to form hematopoietic cell colonies in methylcellulose media and in co-cultures with stromal cells; CD45(low) c-Kit(-) cells that showed a granulocyte morphology; CD45(high) c-Kit(low/-) that exhibited a macrophage morphology. In co-cultures of OP9 stromal cells and freshly prepared AGM cultures, CD45(low) c-Kit(+) cells from the AGM culture had the abilities to reproduce CD45(low) c-Kit(+) cells and differentiate into CD45(low) c-Kit(-) and CD45(high) c-Kit(low/-) cells, whereas CD45(low) c-Kit(-) and CD45(high) c-Kit(low/-) did not produce CD45(low) c-Kit(+) cells. Furthermore, CD45(low) c-Kit(+) cells displayed a long-term repopulating activity in adult hematopoietic tissue when transplanted into the liver of irradiated newborn mice. These results indicate that CD45(low) c-Kit(+) cells from the AGM culture have the potential to reconstitute multi-lineage hematopoietic cells.
  Experimental Cell Research 04/2007; 313(5):965-74. · 3.58 Impact Factor
• Article: Inhibitory effects of homeodomain-interacting protein kinase 2 on the aorta-gonad-mesonephros hematopoiesis.

  Naoki Ohtsu, Ikuo Nobuhisa, Miyuki Mochita, Tetsuya Taga
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  ABSTRACT: Definitive hematopoiesis starts in the aorta-gonad-mesonephros (AGM) region of the mouse embryo. Our previous studies revealed that STAT3, a gp130 downstream transcription factor, is required for AGM hematopoiesis and that homeodomain-interacting protein kinase 2 (HIPK2) phosphorylates serine-727 of STAT3. HIPK2 is a serine/threonine kinase known to be involved in transcriptional repression and apoptosis. In the present study, we examined the role of HIPK2 in hematopoiesis in mouse embryo. HIPK2 transcripts were found in fetal hematopoietic tissues such as the mouse AGM region and fetal liver. In cultured AGM cells, HIPK2 protein was detected in adherent cells. Functional analyses of HIPK2 were carried out by introducing wild-type and mutant HIPK2 constructs into AGM cultures. Production of CD45(+) hematopoietic cells was suppressed by forced expression of HIPK2 in AGM cultures. This suppression required the kinase domain and nuclear localization signals of HIPK2, but the kinase activity was dispensable. HIPK2-overexpressing AGM-derived nonadherent cells did not form cobblestone-like colonies in cultures with stromal cells. Furthermore, overexpression of HIPK2 in AGM cultures impeded the expansion of CD45(low)c-Kit(+) cells, which exhibit the immature hematopoietic progenitor phenotype. These data indicate that HIPK2 plays a negative regulatory role in AGM hematopoiesis in the mouse embryo.
  Experimental Cell Research 02/2007; 313(1):88-97. · 3.58 Impact Factor
• Article: [Roles of BMP in the development of the central nervous system].

  Shinji Fukuda, Tetsuya Taga
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  ABSTRACT: Bone morphogenetic protein (BMP) signaling is involved in astrocytic differentiation of neural precursor cells. In the nuclei, BMP-downstream transcription factors, i.e. Smad proteins, induce expression of astrocyte-specific genes in cooperation with another cytokine signaling, while inhibiting neuronal and oligodendrocytic differentiation-inducing transcription factors. This cross-inhibitory mechanism contributes to exclusive astrocytic differentiation. Crosstalk among cytokine signaling pathways thus is important for the development of the central nervous system.
  Clinical calcium 06/2006; 16(5):781-85.
• Article: Basic fibroblast growth factor endows dorsal telencephalic neural progenitors with the ability to differentiate into oligodendrocytes but not gamma-aminobutyric acidergic neurons.

  Masahiko Abematsu, Tetsushi Kagawa, Shinji Fukuda, Toshihiro Inoue, Hirohide Takebayashi, Setsuro Komiya, Tetsuya Taga
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  ABSTRACT: Basic fibroblast growth factor (bFGF) is commonly used to enrich and maintain neural stem cells in vitro. Olig2 is an essential transcription factor for oligodendrocyte lineage specification and is expressed predominantly in ventral neuroepithelial cells in the medial and lateral ganglionic eminence (GE), where oligodendrocyte progenitors originate. Here we report significant induction of Olig2 expression in dorsal neuroepithelium-derived cells cultured in the presence of bFGF, in which Olig2-expressing cells were initially negligible. Among Olig2-expressing cells appearing after a 5-day treatment with bFGF, 99.8% coexpressed nestin. There was no significant difference in proliferation or apoptosis in dorsal and ventral neuroepithelial cultures in the presence of bFGF, suggesting that bFGF induces ectopic expression of Olig2 in dorsal "cortical" neuroepithelial cells. Similarly, expression of Mash1, another ventral neuroepithelial cell marker gene, was also induced in cultured dorsal neuroepithelial cells in the presence of bFGF. Conversely, in this culture, expression of dorsal neuroepithelial cell markers, such as Neurogenin1, Neurogenin2, Pax6, and Emx2, was down-regulated. These results suggested a possible ventralizing activity of bFGF. In fact, bFGF-treated dorsal neuroepithelial cells acquired the potential to generate O4-positive oligodendrocytes with efficacy comparable to that observed with GE-derived cells. In marked contrast, bFGF did not enable dorsal neuroepithelial cells to generate gamma-aminobutyric acid (GABA) neurons, which normally develop only from GE in vivo. Thus, bFGF endows dorsal telencephalic neural progenitors with the ability to differentiate into oligodendrocytes but not GABAergic neurons, suggesting the presence of different mechanisms governing specification of dorsoventral cell identities of neuronal and glial cell lineages.
  Journal of Neuroscience Research 05/2006; 83(5):731-43. · 2.74 Impact Factor
• Source

  Available from: hematologylibrary.org

  Article: Enhanced engraftment of hematopoietic stem/progenitor cells by the transient inhibition of an adaptor protein, Lnk.

  Hitoshi Takizawa, Chiyomi Kubo-Akashi, Ikuo Nobuhisa, Sang-Mo Kwon, Masanori Iseki, Tetsuya Taga, Kiyoshi Takatsu, Satoshi Takaki
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  ABSTRACT: Hematopoietic stem cells (HSCs) are the key elements responsible for maintaining blood-cell production throughout life and for lymphohematopoietic reconstitution following bone marrow (BM) transplantation. Enhancement of the engrafting potential and expansion capabilities of HSCs as well as hematopoietic progenitor cells (HPCs) has been a long-time desire as a means of reducing the risks and difficulties that accompany BM transplantation. The ability of HSCs/HPCs to reconstitute the hematopoietic system of irradiated hosts is negatively regulated by an intracellular adaptor protein, Lnk. Here we have identified the functional domains of Lnk and developed a dominant-negative (DN) Lnk mutant that inhibits the functions of Lnk endogenously expressed in the HSCs/HPCs and thereby potentiates the HSCs/HPCs for engraftment. Importantly, even transient expression of DN-Lnk in HSCs/HPCs facilitated their engraftment under nonmyeloablative conditions and fully reconstituted the lymphoid compartments of immunodeficient host animals. HPCs expressing DN-Lnk were efficiently trapped by immobilized vascular cell adhesion molecule-1 (VCAM-1) in a transwell migration assay, suggesting involvement of Lnk in the regulation of cell mobility or cellular interaction in microenvironments. Transient inhibition of Lnk or Lnk-mediated pathways could be a potent approach to augment engraftment of HSCs/HPCs without obvious side effects.
  Blood 05/2006; 107(7):2968-75. · 9.90 Impact Factor
• Article: [Identification of cancer stem cells in the "side population"].

  Tetsuya Taga
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  ABSTRACT: Both normal somatic stem cells and cancer cells are thought to be capable of unlimited proliferation. Paradoxically, however, some cancers seem to contain stem-like cells (cancer stem cells). There is increasing evidence that cancers might contain their own stem cells. Many cancers, like normal organs, seem to be maintained by a hierarchical organization that includes slowly dividing stem cells,rapidly dividing transit amplifying cells (precursor cells), and differentiated cells. Malignant gliomas, for example,often contain both undifferentiated and differentiated cells and sometimes contain cells that express neuronal markers as well as cells that express glial markers, suggesting that they may contain multipotent neural stem cell-like cells. We have shown that some cancer cell lines contain a small side population (SP), which, in many normal tissues, is thought to contain the stem cells of the tissue. We provide evidence that SP cells in the C6 glioma cell line can produce both neurons and glial cells and thus have cancer stem cell property. Taken together with studies on normal neural stem cells, studies on cancer stem cells will help us to understand a link between normal stem cells and cancer stem cells.
  Gan to kagaku ryoho. Cancer & chemotherapy 04/2006; 33(3):295-9.
• Article: Activation of canonical Wnt pathway promotes proliferation of retinal stem cells derived from adult mouse ciliary margin.

  Toshihiro Inoue, Tetsushi Kagawa, Mikiko Fukushima, Takeshi Shimizu, Yutaka Yoshinaga, Shinji Takada, Hidenobu Tanihara, Tetsuya Taga
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  ABSTRACT: Adult retinal stem cells represent a possible cell source for the treatment of retinal degeneration. However, only a small number of stem cells reside in the ciliary margin. The present study aimed to promote the proliferation of adult retinal stem cells via the Wnt signaling pathway. Ciliary margin cells from 8-week-old mice were dissociated and cultured to allow sphere colony formation. Wnt3a, a glycogen synthase kinase (GSK) 3 inhibitor, fibroblast growth factor (FGF) 2, and a FGF receptor inhibitor were then applied in the culture media. The primary spheres were dissociated to prepare either monolayer or secondary sphere cultures. Wnt3a increased the size of the primary spheres and the number of Ki-67-positive proliferating cells in monolayer culture. The Wnt3a-treated primary sphere cells were capable of self-renewal and gave rise to fourfold the number of secondary spheres compared with nontreated sphere cells. These cells also retained their multilineage potential to express several retinal markers under differentiating culture conditions. The Wnt3a-treated cells showed nuclear accumulation of beta-catenin, and a GSK3 inhibitor, SB216763, mimicked the mitogenic activity of Wnt3a. The proliferative effect of SB216763 was attenuated by an FGF receptor inhibitor but was enhanced by FGF2, with Ki-67-positive cells reaching over 70% of the total cells. Wnt3a and SB216763 promoted the proliferation of retinal stem cells, and this was partly dependent on FGF2 signaling. A combination of Wnt and FGF signaling may provide a therapeutic strategy for in vitro expansion or in vivo activation of adult retinal stem cells.
  Stem Cells 02/2006; 24(1):95-104. · 7.78 Impact Factor
• Article: [Cancer stem cells in cancer cell lines].

  Takao Setoguchi, Toru Kondo, Tetsuya Taga
  Tanpakushitsu kakusan koso. Protein, nucleic acid, enzyme 01/2006; 50(15):1995-2000.
• Article: Characterization of glycoconjugate antigens in mouse embryonic neural precursor cells.

  Makoto Yanagisawa, Tetsuya Taga, Kazuo Nakamura, Toshio Ariga, Robert K Yu
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  ABSTRACT: Neuronal and glial cells organizing the central nervous system (CNS) are generated from common neural precursor cells (NPCs) during neural development. However, the expression of cell-surface glycoconjugates that are crucial for determining the properties and biological function of these cells at different stages of development has not been clearly defined. In this study, we investigated the expression of several stage-specific glycoconjugate antigens, including several b-series gangliosides GD3, 9-O-acetyl GD3, GT1b and GQ1b, stage-specific embryonic antigen-1 (SSEA-1) and HNK-1, in mouse embryonic NPCs employing immunocytochemistry and flow cytometry. In addition, several of these antigens were positively identified by chemical means for the first time. We further showed that the SSEA-1 immunoreactivity was contributed by both glycoprotein and glycolipid antigens, and that of HNK-1 was contributed only by glycoproteins. Functionally, SSEA-1 may participate in migration of the cells from neurospheres in an NPC cell culture system, and the effect could be repressed by anti-SSEA-1 antibody. Based on this observation, we identified beta1 integrin as one of the SSEA-1 carrier glycoproteins. Our data thus provide insights into the functional role of certain glycoconjugate antigens in NPCs during neural development.
  Journal of Neurochemistry 01/2006; 95(5):1311-20. · 4.06 Impact Factor
• Article: Fate redirection of hippocampal astrocytes toward neuronal lineage by aggregate culture.

  Makoto Yanagisawa, Kinichi Nakashima, Wataru Ochiai, Takumi Takizawa, Takao Setoguchi, Atsumi Uemura, Makiko Takizawa, Ikuo Nobuhisa, Tetsuya Taga
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  ABSTRACT: Mammalian cells that have been committed to a certain cell lineage cannot be directed to other lineages. However, some astrocytes in the mammalian brains have been reported to represent plasticity to redirect to other cell lineages. We found that mouse hippocampal astrocytes cultured in aggregate forms of "astrosphere", redirected to MAP2-positive immature neurons. In astrospheres, basic HLH factors positively regulating neuronal differentiation were up-regulated and Id3 inhibiting basic HLH factors was down-regulated. Ectopic Id3 induction repressed redirection of astrocytes to a neuronal lineage, suggesting that astrosphere formation induced plasticity of astrocytes by changing the gene expression patterns.
  Neuroscience Research 11/2005; 53(2):176-82. · 2.25 Impact Factor
• Article: Preferential differentiation of neural progenitor cells into the glial lineage through gp130 signaling in N-methyl-D-aspartate-treated retinas.

  Yuki Mawatari, Mikiko Fukushima, Toshihiro Inoue, Takao Setoguchi, Tetsuya Taga, Hidenobu Tanihara
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  ABSTRACT: The purpose of this study was to investigate the differentiation of neural progenitor cells (NPCs) following retinal transplantation in N-methyl-D-aspartate (NMDA)-treated eyes. NMDA was injected into the vitreous cavity of adult rat eyes. NPCs were prepared from telencephalic neuroepithelium of enhanced green fluorescence protein (EGFP) transgenic mice on embryonic day 14.5. A cell suspension was injected into the vitreous cavity in experimental eyes. Immunohistochemistry was conducted at 1, 2 or 4 weeks after transplantation of NPCs in an effort to determine the survival and differentiation of transplanted NPCs. Similar experiments were conducted using glycoprotein (gp)130-null (-/-) mice. Examination of retinal sections revealed that transplanted NPCs could survive for at least 4 weeks in NMDA-treated retinas. Immunohistochemical studies for specific cell-type markers revealed that, among the transplanted NPCs at 2 weeks after transplantation, the mean percentage (+/-standard deviation) of glial fibrillary acidic protein (GFAP)-positive (glial) cells was 63.5 +/- 7.4%, demonstrating the differentiation of transplanted NPCs with a preference for the glial lineage. Furthermore, the mean percentage of betaIII-tubulin-positive (mature neuronal) cells was 18.8 +/- 4.5%. Following transplantation of NPCs isolated from gp130-/- mice into NMDA-treated retinas, the mean percentage of GFAP-positive cells (17.6 +/- 7.0%), was significantly lower than that in NPCs isolated from wild-type mice (59.1 +/- 6.0%, P = 0.04, Mann-Whitney U test). Preferential differentiation of NPCs into the glial lineage is induced through gp130 signaling in NMDA-treated eyes.
  Brain Research 10/2005; 1055(1-2):7-14. · 2.73 Impact Factor