研究者詳細 - 岡野　栄之

論文 - 岡野　栄之

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Augmentation by calmodulin of ADP-ribosylation factor-stimulated phospholipase D activity in permeabilized rabbit peritoneal neutrophils

Takahashi K. I., Tago K., Okano H., Ohya Y., Katada T., Kanaho Y.

Journal of Immunology 156 （ 3 ） 1229 - 1234 1996年

ISSN 0022-1767

Activation of the membrane-bound phospholipase D (PLD) requires cytosolic factor(s), and ADP-ribosylation factor (ARF) has been identified as a cytosolic PLD activator. In the present study, we demonstrate that calmodulin (CaM) and ARF are both involved in PLD activation in rabbit peritoneal neutrophils. The PLD activity of streptolysin O-permeabilized, cytosol- depleted rabbit neutrophils was significantly enhanced when the permeabilized cells were reconstituted with bovine brain cytosol in the presence of guanosine 5'-O-(3-thiotriphosphate) (GTPγS), whereas there was little activation of the enzyme in the absence of cytosol. The GTPγS-stimulated PLD activity in the presence of cytosol was augmented on increasing the concentration of free Ca²⁺. The PLD activity stimulated by GTPγS and Ca²⁺ in this system was inhibited by the calmodulin inhibitor W-7. These findings suggest that CaM plays a role as a cytosolic PLD activator. Moreover, highly purified CaM alone, as well as partially purified ARF alone, promoted a slight stimulation of the PLD activity in permeabilized neutrophils. Interestingly, ARF-stimulated PLD activity was augmented by CaM in the presence of GTPγS and Ca²⁺. This augmentation was again inhibited by W-7, as well as by the structurally unrelated CaM inhibitor trifluoperazine. These data imply that CaM stimulates the PLD activity of rabbit neutrophils in concert with ARF.

hiiragi, a gene essential for wing development in Drosophila melanogaster, affects the Notch cascade

Murata Takehide, Ogura Keiji, Murakami Ryutaro, Okano Hideyuki, Yokoyama Kazunari K.

Genes and Genetic Systems 71 （ 4 ） 247 - 254 1996年

ISSN 1341-7568

A recessive mutation, hiiragi(P1), on the second chromosome of Drosophila was obtained by P element insertion mutagenesis. Flies homozygous for hiiragi(P1) have notched wing margins. Genetic interactions between hiiragi and the genes that encode components of Notch signaling, such as Notch, Hairless, Serrate and deltex, strongly support the involvement of hiiragi in the signal transduction cascade of Notch. It has been reported that Serrate and Delta, other components of Notch signaling, share EGF-like repeats and a second conserved cysteine-rich motif, and that these components interact physically with the same region of Notch. In hiiragi(P1); Serrate(D)/+ double mutants, we observed synergistic enhancement of the notched phenotype of wing margins. In contrast, Delta(FX3) had no phenotypic effect on hiiragi(P1) in hiiragi(P1); Delta(FX3)/+ double mutants. Taken together, these results indicate that hiiragi is involved in the Notch signaling cascade induced by Serrate rather than by Delta.

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argos Is required for projection of photoreceptor axons during optic lobe development in Drosophila

Sawamoto Kazunobu, Okabe Masataka, Tanimura Teiichi, Hayashi Shigeo, Mikoshiba Katsuhiko, Okano Hideyuki

Developmental Dynamics 205 （ 2 ） 162 - 171 1996年

ISSN 1058-8388

The Drosophila argos gene encodes a secreted protein with an epidermal growth factor (EGF) motif, which acts as an inhibitor of cell recruitment in the developing eye and wing. Here, we have analyzed the role of argos during optic lobe development, argos expression was observed in the optic lobes throughout the developmental stages. In argos mutants, neuropiles failed to develop normally during embryonic and larval stages, and photoreceptor axons did not project properly into the lamina. Ubiquitous expression of argos, under control of the hsp70 promoter, rescued the defects in optic lobes. We have found that glial cells failed to differentiate in the larval optic lobes of argos mutants. Correspondingly, in loss-of-function repo mutants, whose glial cells also fail to differentiate, photoreceptor axons showed the impaired projection pattern similar to the argos phenotype. These results suggest that glial cells play a role for guidance of photoreceptor axons. The loss-of-function Star mutation (Star(X155)) dominantly suppressed the defects in the argos optic lobes, suggesting that these two genes act in an antagonistic fashion during optic lobe development.

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Role of inositol 1,4,5-trisphosphate receptor in ventral signaling in xenopus embryos

Kume Shoen, Muto Akira, Inoue Takafumi, Suga Kei, Okano Hideyuki, Mikoshiba Katsuhiko

Science 278 （ 5345 ） 1940 - 1943 1997年12月

ISSN 0036-8075

The inositol 1,4,5-trisphosphate (IP₃) receptor is a calcium ion channel involved in the release of free Ca²⁺ from intracellular stores. For analysis of the role of IP₃-induced Ca²⁺ release (IICR) on patterning of the embryonic body, monoclonal antibodies that inhibit IICR were produced. Injection of these blocking antibodies into the ventral part of early Xenopus embryos induced modest dorsal differentiation. A close correlation between IICR blocking potencies and ectopic dorsal axis induction frequency suggests that an active IP₃-Ca²⁺ signal may participate in the modulation of ventral differentiation.

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Bcl-2 prevents TNF- and Fas-induced cell death but does not inhibit initial processing of caspase-3

Shiraiwa Nobuko, Okano Hideyuki, Miura Masayuki

Biomedical Research 18 （ 6 ） 405 - 411 1997年12月

ISSN 0388-6107

The members of ICE/CED3 family of cysteine proteases (caspases) play important roles in the regulation of programmed cell death. Recent studies have revealed that processing and activation of CPP32 (CASP-3) are crucial for executing cell death in TNF-α- and Fas-induced apoptosis. Overexpression of Bcl-2 in HeLa cells inhibits the cell death and CASP-3 like protease activities which are induced by TNF-α or anti-Fas antibody. Preform of CASP-3 disappered after the treatment with TNF-α or anti-Fas antibody in both HeLa cells and HeLa/bcl-2 cells. These results suggest Bcl-2 prevents cell death and activation of CASP-3 but does not inhibit initial processing of CASP-3.

Recognition of tissue- and subtype- specific modulation of angiotensin II receptors using antibodies against AT1 and AT2 receptors

Rakugi Hiromi, Okamura Atsushi, Kamide Koichi, Ohishi Hiroshi, Sasamura Hiroyuki, Morishita Ryuichi, Higaki Jitsuo, Ogihara Toshio

Hypertens Res 20 （ 5 ） 51-56 1997年12月

研究論文（学術雑誌）, 共著

Evolutionarily conserved mechanisms regulating neural development

Okano H., Okabe M., Taguchi A., Sawamoto K.

Human cell : official journal of Human Cell Research Society 10 （ 3 ） 139 - 150 1997年09月

ISSN 0914-7470

Functions of genes regulating the development of Drosophila peripheral nervous systems are summarized herein. These genes can be classified into 6 groups: <1> prepattern genes, <2> proneural genes, <3> neurogenic genes, <4> neuronal precursor genes, <5> neuronal precursor type selector genes, and <6> cell-division and lineage genes. The mechanisms described herein provide excellent paradigms in the regulation of the development of other tissues in Drosophila, as well as in other organisms, including vertebrates. The roles of two different inhibitory mechanisms, i.e. Notch-signaling and Argos, in the development of Drosophila neural precursor cells are also discussed.

Demonstration of an E-box and its CNS-related binding factors for transcriptional regulation of the mouse type inositol 1,4,5-trisphosphate receptor gene

Konishi Yoshiyuki, Kobayashi Yasushi, Kishimoto Toshihiko, Makino Yasutaka, Miyawaki Atsushi, Furuichi Teiichi, Okano Hideyuki, Mikoshiba Katsuhiko, Tamura Taka Aki

Journal of Neurochemistry 69 （ 2 ） 476 - 484 1997年08月

ISSN 0022-3042

The type 1 inositol 1,4,5-trisphosphate receptor (IP₃R1) is expressed abundantly in the CNS, such as in cerebellar Purkinje cells and the hippocampus. We established a tissue-specific cell-free transcription system and studied regulatory properties of the 5' upstream region of the IP₃R1 gene by use of this system. Deletion analyses of the promoter revealed several cis elements that function significantly in brain nuclear extracts. Among those elements, sequences from -396 to -295 showed the most predominant cerebellum-specific positive function. Footprint analyses demonstrated a factor-binding region from -334 to -318, termed box-I, that contained an E- box consensus sequence. Electrophoretic mobility shift assay revealed CNS- related basic helix-loop-helix proteins for the box-I. Mutational studies using the function assay end competitive electrophoretic mobility shift assays demonstrated a good correlation between the box-I-binding factors and the activated transcription. Box-I-binding factors were present abundantly in adult mouse CNS, whereas their existence was restricted in embryonic and nonneural tissues. Transient chloramphenicol acetyltransferase assay for the IP₃R1 promoter revealed the requirement of box-I in Neuro2a neuroblastoma cells. In the postnatal CNS, multiple basic helix-loop-helix factors are expressed abundantly, some of which are suggested to activate IP₃R1 gene expression in the mammalian CNS.

Developmental expression of the inositol 1,4,5-trisphosphate receptor and localization of inositol 1,4,5-trisphosphate during early embryogenesis in Xenopus laevis

Kume Shoen, Muto Akira, Okano Hideyuki, Mikoshiba Katsuhiko

Mechanisms of Development 66 （ 1-2 ） 157 - 168 1997年08月

ISSN 0925-4773

To study the role of inositol 1,4,5-trisphosphate (IP₃) receptors during early embryogenesis in Xenopus, we examined the temporal-spatial localization of Xenopus IP₃ receptor (XIP3R), XIP3R protein is enriched in the animal hemisphere of early cleavage stage embryos and becomes localized in the ectoderm and involuted mesoderm in gastrula stage embryos. Up to tailbud stages, expression of XIP3R is observed in the mesodermal tissues and in most subregions of the central nervous system. A quantitative analysis of endogenous IP₃ mass during normal early embryogenesis revealed an increase in IP₃ mass first observed at early gastrula stage of 10.5 with an enrichment in the ectoderm throughout the gastrula stages, implying a potential role during gastrulation.

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ICE/CED-3 family executes oligodendrocyte apoptosis by tumor necrosis factor

Hisahara Shin, Shoji ShiN'ichi, Okano Hideyuki, Miura Masayuki

Journal of Neurochemistry 69 （ 1 ） 10 - 20 1997年07月

ISSN 0022-3042

Tumor necrosis factor (TNF) is thought to be one of the mediators responsible for the damage of oligodendrocytes (OLGs) in multiple sclerosis (MS). We report here the involvement of the interleukin 1β-converting enzyme (ICE)/Caenorhabditis elegans gene ced-3 (CED-3) family in TNF-mediated cell death of OLGs. The addition of TNF-α to primary cultures of OLGs that express ice and cpp32 significantly decreased the number of live OLGs in 72 h. DNA fragmentation was detected in TNF-treated OLGs at 36 h with the terminal deoxynucleotidyl transferase dUTP nick end-labeling assay. Benzyloxycarbonyl-Asp-CH ₂OC(O)-2,6-dichlorobenzene, an inhibitor of the ICE/CED-3 family that shows p35-like inhibitory specificity, protected against the TNF-induced cell death of OLGs. Furthermore, acetyl-YVAD-CHO (a specific inhibitor of ICE-like proteases) as well as acetyl-DEVD-CHO (a specific inhibitor of CPP32-like proteases) enhanced the survival of OLGs treated with TNF-α, indicating that ICE- and the CPP32-mediated cell death pathways are activated in TNF-induced OLG cell death. Our results suggest that the inhibition of ICE/CED-3 proteases may be a novel approach to treat neurodegenerative diseases such as MS.

Two-step induction of chordotonal organ precursors in Drosophila embryogenesis

Okabe Masataka, Okano Hideyuki

Development 124 （ 5 ） 1045 - 1053 1997年03月

ISSN 0950-1991

The chordotonal (Ch) organ, an internal stretch receptor located in the subepidermal layer, is one of the major sensory organs in the peripheral nervous system of Drosophila melantogaster. Although the cell lineage of the Ch organ has been well characterized in many studies, the determination machinery of Ch organ precursor cells (COPs) remains largely unresolved. Here we report that the rhomboid (rho) gene and the activity of the Drosophila EGF receptor (DER) signaling pathway are necessary to induce specifically three of the eight COPs in an embryonic abdominal hemisegment. The cell-lineage analysis of COPs using the yeast flpase (flp/FRT) method indicated that each of the eight COPs originated from an individual undifferentiated ectodermal cell. The eight COPs in each abdominal hemisegment seemed to be determined by a two-phase induction: first, five COPs are determined by the action of the proneural gene atonal and neurogenic genes. Subsequently, these five COPs start to express the rho gene, and rho activates the DER-signaling pathway in neighboring cells and induces argos expression. Three of these argos-expressing cells differentiate into the three remaining COPs and they prevent neighboring cells from becoming extra COPs.

Structural properties and RNA-binding activities of two RNA recognition motifs of a mouse neural RNA-binding protein, mouse-Musashi-1

Kurihara Yasuyuki, Nagata Takashi, Imai Takao, Hiwatashi Ado, Horiuchi Masataka, Sakakibara Shin ichi, Katahira Masato, Okano Hideyuki, Uesugi Seiichi

Gene 186 （ 1 ） 21 - 27 1997年02月

ISSN 0378-1119

mouse-Musashi-1 (m-Msi-1) is an RNA-binding protein, abundantly expressed in the developing mammalian central nervous system (CNS). m-Msi-1 contains two RNA recognition motifs (RRMs). In this study, we found that the N-terminal RRM of m-Msi-1 (MMA) binds strongly to poly(G) and weakly to poly(U) in a way similar to that of the full-length m-Msi-1 protein characterized previously. The C-terminal RRM of m-Msi-1 (MMB), however, does not bind to RNA. In addition, the circular dichroism (CD) spectra of the two RRMs showed that the α-helical content of MMA is significantly higher than that of MMB, indicating that some differences in the secondary structure may be responsible for the distinct RNA binding properties of MMA and MMB.

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Developmental expression of the inositol 1,4,5-trisphosphate receptor and structural changes in the endoplasmic reticulum during oogenesis and meiotic maturation of Xenopus laevis

Kume Shoen, Yamamoto Akitsugu, Inoue Takafumi, Muto Akira, Okano Hideyuki, Mikoshiba Katsuhiko

Developmental Biology 182 （ 2 ） 228 - 239 1997年02月

ISSN 0012-1606

To study the development of the calcium release mechanism, we examined the temporal and spatial expression of inositol 1,4,5-trisphosphate receptor (IP3R) during the oogenesis and meiotic maturation of Xenopus laevis. Observation of a series of fixed samples by immunofluorescence microscopy revealed a relocalization of Xenopus IP3R (XIP3R)-positive structures during meiotic maturation. We visualized the endoplasmic reticulum (ER) using ER-sensitive dye, DiI, by observation under confocal laser scanning microscopy. Time-lapse visualization of the living oocytes revealed that while the ER of immature fully grown oocytes underwent relatively little movement, the ER of maturing oocytes and mature eggs moved rapidly. A possible role for the increase of ER mobility in the dynamic redistribution of XIP3R during oocyte maturation is also discussed.

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Intrinsic and extrinsic determinants regulating cell fate decision in developing nervous system

Okabe Masataka, Sawamoto Kazunobu, Imai Takao, Sakakibara Shin Ichi, Yoshikawa Shingo, Okano Hideyuki

Developmental Neuroscience 19 （ 1 ） 9 - 16 1997年01月

ISSN 0378-5866

Cell fate in the nervous system is determined by environmental signals and/or heredity. They can be referred to as extrinsic and intrinsic determinants, respectively. The molecular and cellular mechanisms underlying these processes are well conserved from invertebrates to vertebrates. We have identified both types of determinants through the intensive screening of P-element-induced Drosophila mutants affected in neural development. As a member of the first category, argos gene product which regulates cell-cell interaction in the developing nervous system gives a good example. As a member of the second category, we refer to Drosophila musashi gene encoding a neural RNA-binding protein. The functions of these gene products and application to the mammalian nervous system will be discussed.

Expression of neural RNA-binding proteins in the postnatal CNS

Sakakibara Shin Ichi, Okano Hideyuki

Journal of Neuroscience 17 （ 21 ） 8300 - 8312 1997年

ISSN 0270-6474

There is an increasing interest in the role of RNA-binding proteins during neural development. Mouse-Musashi-1 (m-Msi-1) is a mouse neural RNA- binding protein with sequence similarity to Drosophila musashi (d-msi), which is essential for neural development. m-Msi-1 is highly enriched in neural precursor cells that are capable of generating both neurons and glia during embryonic CNS development. The present study characterized m-Msi-1-expressing cells in the postnatal and adult CNS. Postnatally, m-Msi-1 was expressed in proliferative neuronal precursors in the external granule cell layer of the cerebellum and in the anterior corner of the subventricular zone of the lateral ventricles. In gliogenesis, the persistent expression of m-Msi-1 was observed in cells of the astrocyte lineage ranging from proliferative glial precursors in the subventricular zone (SVZ), to differentiated astrocytes in the parenchyma. In addition, we showed that m-Mis-1 was still expressed in proliferating cells in the adult SVZ, which may contain neural precursor or stem cells. Another neural RNA-binding protein Hu (the mammalian homolog of Drosophila neuronal RNA-binding protein Elav) was present in postmitotic neurons throughout the development of the CNS, and its pattern of expression was compared with that of m-Msi-1. These observations imply that these two RNA-binding proteins may be involved in the development of neurons and glia by regulating gene expression at the post-transcriptional level.

Execution mechanisms of programmed cell death by caspase (ICE/CED-3) family proteases

Miura Masayuki, Hisahara Shin, Araki Takashi, Okano Hideyuki

Heart and Vessels 12 （ SUPPL. 12 ） 66 - 70 1997年

ISSN 0910-8327

Molecular genetic study of Caenorhabditis elegans revealed the cell death-executing gene ced-3. Structural and functional similarities between CED-3 and mammalian ICE family (caspase) gene products provide the evidence that mammalian caspases are common mediators in executing programmed cell death. These findings suggest that the execution mechanisms of cell death by caspase family protease may be evolutionarily conserved from worms to mammals. This report summarizes the unique properties of caspases in apoptosis.

A novel Drosophila paired-like homeobox gene related to Caenorhabditis elegans unc-4 is expressed in subsets of postmitotic neurons and epidermal cells

Tabuchi Katsuhiko, Yoshikawa Shingo, Yuasa Yoshihiro, Sawamoto Kazunobu, Okano Hideyuki

Neuroscience Letters 257 （ 1 ） 49 - 52 1998年11月

ISSN 0304-3940

We have isolated a novel Drosophila paired-like homeobox gene, DPHD-1. The homeodomain of DPHD-1 showed 85% amino-acid identity with that of the C. elegans Unc-4 protein. Whole-mount in situ hybridization of embryos and third-instar larvae revealed that the DPHD-1 mRNA is specifically localized in subsets of postmitotic neurons in the central nervous system (CNS) and in the developing epidermis with a segmentally repeated pattern. Double staining with a posterior compartment marker, an anti-Engrailed antibody, showed that DPHD-1 expressing neurons in the CNS were present in the posterior compartment, whereas DPHD-1 expression in the epidermis was restricted to the anterior compartment in each segment. This temporal and spatial expression pattern suggests that DPHD-1 may play a role in determining the distinct cell types in each segment.

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The human Musashi homolog 1 (MSI1) gene encoding the homologue of Musashi/Nrp-1, a neural RNA-binding protein putatively expressed in CNS stem cells and neural progenitor cells

Good Peter, Yoda Akinori, Sakakibara Shin Ichi, Yamamoto Atsuyo, Imai Takao, Sawa Hitoshi, Ikeuchi Takeshi, Tsuji Shoji, Satoh Hitoshi, Okano Hideyuki

Genomics 52 （ 3 ） 382 - 384 1998年09月

ISSN 0888-7543

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Mammalian BarH homologue is a potential regulator of neural bHLH genes

Saito Tetsuichiro, Sawamoto Kazunobu, Okano Hideyuki, Anderson David J., Mikoshiba Katsuhiko

Developmental Biology 199 （ 2 ） 216 - 225 1998年07月

ISSN 0012-1606

Vertebrate neurogenesis involves sequential actions of transcription factors. neurogenins, encoding Atonal-related bHLH transcription factors, function as neuronal determination genes in Xenopus. neurogenins and another bHLH factor gene, Mash1, are expressed in distinct subsets or areas of cells giving rise to neurons, suggesting that these genes play important roles to generate distinct populations of neurons. A mammalian homologue of BarH (MBH1) is expressed in a complementary pattern to Mash1 expression in the developing nervous system like neurogenins. Forced expression of MBH1 down- regulates expression of Mash1 and up-regulates neurogenin2/Math4A, a member of neurogenins, in P19 cells during neuronal differentiation. This suggests that MBH1 is a potential regulator of mammalian neural bHLH genes, thereby establishing distinct pathways of neuronal differentiation.

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Fibroblast growth factor-2/brain-derived neurotrophic factor-associated maturation of new neurons generated from adult human subependymal cells

Pincus David W., Keyoung H. Michael, Harrison-Restelli Catherine, Goodman Robert R., Fraser Richard A R, Edgar Mark, Sakakibara Shin Ichi, Okano Hideyuki, Nedergaard Maiken, Goldman Steven A.

Annals of Neurology 43 （ 5 ） 576 - 585 1998年05月

ISSN 0364-5134

The adult mammalian forebrain harbors neuronal precursor cells in the subependymal zone (SZ). Neuronal progenitors also persist in the adult human SZ and have been cultured from epileptic temporal lobe. In the present study, we sought to identify these neural progenitors in situ, and to direct their expansion and neuronal differentiation in vitro. We prepared explants of adult human SZ, obtained from temporal lobe resections of refractory epileptics. The resultant cultures were treated with fibroblast growth factor-2 (FGF-2) for a week, with concurrent exposure to [³H]thymidine, then switched to media containing brain-derived neurotrophic factor (BDNF) for up to 2 months. Sporadic neuronal outgrowth, verified antigenically and physiologically, was observed from SZ cultures regardless of FGF-2/BDNF treatment; however, only FGF-2/BDNF-treated cultures exhibited profuse outgrowth, and these displayed neuronal survival as long as 9 weeks in vitro. In addition, cortical cultures derived from two brains generated microtubule- associated protein-2⁺ neurons, which incorporated [³H]thymidine and exhibited significant calcium increments to depolarization. In histological sections of the subependyma, both uncommitted and restricted progenitors, defined respectively by musashi and Hu protein expression, were identified. Thus, the adult human subependyma harbors neural progenitors, which are able to give rise to neurons whose numbers can be supported for prolonged periods in vitro.

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