{"created":"2023-06-20T13:20:53.766924+00:00","id":962,"links":{},"metadata":{"_buckets":{"deposit":"2a1f8392-90fc-40dd-b1e8-e6115d020024"},"_deposit":{"created_by":1,"id":"962","owners":[1],"pid":{"revision_id":0,"type":"depid","value":"962"},"status":"published"},"_oai":{"id":"oai:ir.soken.ac.jp:00000962","sets":["2:430:20"]},"author_link":["10031","10029","10030"],"item_1_creator_2":{"attribute_name":"著者名","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"千原, 崇裕"}],"nameIdentifiers":[{}]}]},"item_1_creator_3":{"attribute_name":"フリガナ","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"チハラ, タカヒロ"}],"nameIdentifiers":[{}]}]},"item_1_date_granted_11":{"attribute_name":"学位授与年月日","attribute_value_mlt":[{"subitem_dategranted":"2001-03-23"}]},"item_1_degree_grantor_5":{"attribute_name":"学位授与機関","attribute_value_mlt":[{"subitem_degreegrantor":[{"subitem_degreegrantor_name":"総合研究大学院大学"}]}]},"item_1_degree_name_6":{"attribute_name":"学位名","attribute_value_mlt":[{"subitem_degreename":"博士（理学）"}]},"item_1_description_12":{"attribute_name":"要旨","attribute_value_mlt":[{"subitem_description":"Cell differentiation and cell migration are key processes in the development of multicellular organisms. In the nervous system, for instance, the pattern of cell differentiation and cell migration is tightly regulated in order to form an elaborate neural network. For studies of regulatory mechanisms of cell differentiation and cell migration, the Drosophila tracheal system has become an appropriate model system. The tubular epithelium of the Drosophila tracheal system forms a network with a stereotyped pattern consisting of cells and branches with distinct identity. The tracheal primordium undergoes primary branching due to an induction by the FGF homolog Branchless (Bnl), differentiates into cells with specialized function such as fusion cells that perform target recognition and adhesion during branch fusion, and extends branches toward specific targets. Specification of an unique identity for each primary branch is essential for directed migration, as a defect in either the EGF receptor (EGFR) or Decapentaplegic (Dpp) signalings leads to a loss of branch identity and the misguidance of tracheal cell migration.<br />To elaborate the stereotyped pattern of tracheal network, cell differentiation and cell migration must be tightly regulated during embryogenesis. Following cell differentiation of primary branches, direction of tracheal cell migration must be also regulated so that tracheal branches reach specific targets precisely. However, little is known about what kind of signal in addition to EGFR and Dpp induces differentiation of primary branches and how migration of tracheal cells is guided.<br />Wingless (Wg) is known as a secreted signaling protein essential for segmentation events. The Drosophila β-catenin homolog, Armadillo (Arm), is a downstream component of Wg signaling. Previously it was reported that wg and arm mutant embryos exhibit the severe tracheal defects with loss of specific branch (dorsal trunk) and all tracheal fusion events. Although these phenotypes indicate that Wg signaling is essential for specification of cell and branch identity in the tracheal system, little is known about how Wg signaling acts in the tracheal cells.<br />To investigate the role of Wg signaling in the specification of cell and branch identity in the tracheal system, I first observed expression pattern of Wg during tracheal development, and found that Wg is expressed in stripes of ectodermal cells located on the anterior and posterior side of each tracheal primordium. The tracheal phenotypes in wg temperature-sensitive mutants and zygotic arm mutants were categorized into the following three phenotypes. First one is the invagination defect. In wild-type embryos, tracheal placodes invaginate into the inside of the embryo. But in wg temperature-sensitive mutants invagination failed, and descendants of tracheal placode were retained in the ectodermal layer. Second, dorsal trunk (DT) was lost. DT normally expresses Spalt (Sal) which is essential for the DT identity, but in arm zygotic mutants Sal expression was lost. Finally, tracheal fusion was defective and Escargot (Esg) expression was lost at all fusion points. Esg is a zinc-finger type DNA binding protein, and its expression is required for fusion cell identity. The latter two phenotypes were further investigated, and I demonstrate that Wg signaling is required within tracheal cells for expression of Sal and Esg in tracheal cells. From these results, I show that Wg and its intracellular signal transducer, Arm, have multiple functions, one specifying dorsal trunk through activation of Sal expression and the other inducing differentiation of fusion cells in all fusion branches.<br />Moreover, I demonstrate that Wg signaling regulates not only Esg expression itself, but also singling-out of Esg expressing cell at the tip of migrating branches by regulating Notch activity. Notch is a transmembrane receptor stimulated by a ligand Delta. A single fusion cell expressing Esg always locates at the tip of each migrating branch. High level of Delta expression by Bnl signaling is limited to fusion cell at the tip of tracheal branches. The Delta expression in fusion cell activates Notch signaling in nearby cells and that activated Notch signaling represses the fate of fusion cell. As a result, fusion cell is singled out at the tip of tracheal branches by Notch-dependent lateral inhibition. I here show that expression of Delta is also up-regulated by Wg signaling at the transcriptional level, and the high accumulation of Delta permits Esg expression only in fusion cell. Because Notch activity does not affect Sal expression, expression of Sal is permitted in all DT cells. <br />From these results, I propose that Wg signaling controls the formation of DT by regulating three genes sal, esg, and Delta in distinct ways. Wg signaling activates Sal expression in tracheal cells, and the expression of Sal is required to render DT an identity to become thick tubule and to migrate in anteroposterior direction. Wg signaling also activates Esg in all DT cells. <br />In addition, Wg and Bnl signals are combined to activate Delta expression at the tip of DT. Elevated Delta activates Notch in nearby cells, leading to repression of Esg in the stalk of tracheal branches. Stimulation of both positive and negative regulation of Esg by Wg signaling comprises a self-limiting assignment of single fusion cells that mark the end of tracheal tubule. In combination with the specification of thick tubules through regulation of Sal, Wg signaling determines the shape of the tracheal tubule.<br /><br />In addition to the studies described above, I investigated the guidance mechanism of tracheal cell migration. I focused on well-studied dorsal branch (DB), which migrates dorsally and fuses at the dorsal midline with DB from the other side of the same segment during embryogenesis. Previous studies reported that several signaling molecules (Bnl, Dpp and Notch) affect DB  formation by inducing cell differentiation, but little is known about the guidance mechanism of DB migration. I found that DB fusion points are precisely located posterior to Wg stripes, suggesting that the direction of DB migration must be also tightly regulated.<br />To obtain insight into the guidance mechanism of DB migration, I first observed migration pattern of fusion and terminal cells, a pair of cells that occupy the tip of DB. Fusion cells were identified by expression of Esg and were initially located anterior to terminal cells labeled with SRF expression. After the initial expression of these genes, their relative positions switched. In this process, Esg expressing cells continue to contact Engrailed expressing ectodermal cells. I also analyzed the distribution of actin cytoskeleton in migrating DB, and found that fusion and terminal cells have filopodia and lamellipodia similar to those found in neuronal growth cone.<br />Based on these observations, I next investigated which signaling guides DB migration. I show that planar cell polarity (PCP) signaling has a role in the guidance of DB migration. It is known that PCP signaling regulates small GTPases Rho/Racl activity, and controls cytoskeletal rearrangements within the plane orthogonal to their apical-basal axis. I also show that a component of PCP signaling, Dracl has an essential role on the guidance of DB migration, but not motility of tracheal cells. As it has been reported that axon guidance is regulated by Dracl activity, these results imply that there is a common guidance mechanism in tracheal cell migration and axonal outgrowth.<br /><br />In summary, I demonstrate that Wg signaling controls the shape of tracheal tubule in concert with Notch signaling. In addition, I show the guidance mechanism of tracheal cell migration is similar to that of axon guidance, and demonstrate that PCP signaling has effects on guidance of tracheal cell migration. From these results, I propose that Wg acts on both cell differentiation and the guidance of cell migration via distinct signaling pathway to elaborate Drosophila tracheal network.","subitem_description_type":"Other"}]},"item_1_description_18":{"attribute_name":"フォーマット","attribute_value_mlt":[{"subitem_description":"application/pdf","subitem_description_type":"Other"}]},"item_1_description_7":{"attribute_name":"学位記番号","attribute_value_mlt":[{"subitem_description":"総研大甲第533号","subitem_description_type":"Other"}]},"item_1_select_14":{"attribute_name":"所蔵","attribute_value_mlt":[{"subitem_select_item":"有"}]},"item_1_select_8":{"attribute_name":"研究科","attribute_value_mlt":[{"subitem_select_item":"生命科学研究科"}]},"item_1_select_9":{"attribute_name":"専攻","attribute_value_mlt":[{"subitem_select_item":"18 遺伝学専攻"}]},"item_1_text_10":{"attribute_name":"学位授与年度","attribute_value_mlt":[{"subitem_text_value":"2000"}]},"item_creator":{"attribute_name":"著者","attribute_type":"creator","attribute_value_mlt":[{"creatorNames":[{"creatorName":"CHIHARA, Takahiro","creatorNameLang":"en"}],"nameIdentifiers":[{}]}]},"item_files":{"attribute_name":"ファイル情報","attribute_type":"file","attribute_value_mlt":[{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲533_要旨.pdf","filesize":[{"value":"429.7 kB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"要旨・審査要旨 / Abstract, Screening Result","url":"https://ir.soken.ac.jp/record/962/files/甲533_要旨.pdf"},"version_id":"3da6565f-7de1-49f4-857f-3417ba41ee62"},{"accessrole":"open_date","date":[{"dateType":"Available","dateValue":"2016-02-17"}],"displaytype":"simple","filename":"甲533_本文.pdf","filesize":[{"value":"4.9 MB"}],"format":"application/pdf","licensetype":"license_11","mimetype":"application/pdf","url":{"label":"本文","url":"https://ir.soken.ac.jp/record/962/files/甲533_本文.pdf"},"version_id":"6269be26-abc2-422d-af85-71d5be41fdca"}]},"item_language":{"attribute_name":"言語","attribute_value_mlt":[{"subitem_language":"eng"}]},"item_resource_type":{"attribute_name":"資源タイプ","attribute_value_mlt":[{"resourcetype":"thesis","resourceuri":"http://purl.org/coar/resource_type/c_46ec"}]},"item_title":"Role of Wingless signaling during Drosophila tracheal development","item_titles":{"attribute_name":"タイトル","attribute_value_mlt":[{"subitem_title":"Role of Wingless signaling during Drosophila tracheal development"},{"subitem_title":"Role of Wingless signaling during Drosophila tracheal development","subitem_title_language":"en"}]},"item_type_id":"1","owner":"1","path":["20"],"pubdate":{"attribute_name":"公開日","attribute_value":"2010-02-22"},"publish_date":"2010-02-22","publish_status":"0","recid":"962","relation_version_is_last":true,"title":["Role of Wingless signaling during Drosophila tracheal development"],"weko_creator_id":"1","weko_shared_id":1},"updated":"2023-06-20T14:41:22.391333+00:00"}