title: T-brain homologue (HpTb) is involved in the archenteron induction signals of micromere descendant cells in the sea urchin embryo.
abstract: Signals from micromere descendants play a crucial role in sea urchin development. In this study, we demonstrate that these micromere descendants express HpTb, a T-brain homolog of Hemicentrotus pulcherrimus. HpTb is expressed transiently from the hatched blastula stage through the mesenchyme blastula stage to the gastrula stage. By a combination of embryo microsurgery and antisense morpholino experiments, we show that HpTb is involved in the production of archenteron induction signals. However, HpTb is not involved in the production of signals responsible for the specification of secondary mesenchyme cells, the initial specification of primary mesenchyme cells, or the specification of endoderm. HpTb expression is controlled by nuclear localization of beta-catenin, suggesting that HpTb is in a downstream component of the Wnt signaling cascade. We also propose the possibility that HpTb is involved in the cascade responsible for the production of signals required for the spicule formation as well as signals from the vegetal hemisphere required for the differentiation of aboral ectoderm.
authors.affiliation: Department of Mathematical and Life Sciences, Graduate School of Science, Hiroshima University, Higashi-Hiroshima 739-8526, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Fuchikami
authors.forename: Keiko
authors.initials: K
authors.lastname: Mitsunaga-Nakatsubo
authors.forename: Shonan
authors.initials: S
authors.lastname: Amemiya
authors.forename: Toshiya
authors.initials: T
authors.lastname: Hosomi
authors.forename: Takashi
authors.initials: T
authors.lastname: Watanabe
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kurokawa
authors.forename: Miho
authors.initials: M
authors.lastname: Kataoka
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Harada
authors.forename: Nori
authors.initials: N
authors.lastname: Satoh
authors.forename: Shinichiro
authors.initials: S
authors.lastname: Kusunoki
authors.forename: Kazuko
authors.initials: K
authors.lastname: Takata
authors.forename: Taishin
authors.initials: T
authors.lastname: Shimotori
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Naoaki
authors.initials: N
authors.lastname: Sakamoto
authors.forename: Hiraku
authors.initials: H
authors.lastname: Shimada
authors.forename: Koji
authors.initials: K
authors.lastname: Akasaka
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D053501:Arsenite Transporting ATPases; D001483:Base Sequence; D036703:Blastula / Q000166:cytology / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism; D004475:Ectoderm; D004625:Embryo, Nonmammalian; D004627:Embryonic Induction; D005775:Gastrula; D018507:Gene Expression Regulation, Developmental; D016623:Ion Pumps / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D014176:Protein Biosynthesis; D012617:Sea Urchins / Q000196:embryology* / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D020825:T-Box Domain Proteins / Q000235:genetics* / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D051176:beta Catenin
chemical_list: C495267:CTNNB1 protein, mouse; D003598:Cytoskeletal Proteins; C119263:HpEts protein, Hemicentrotus pulcherrimus; D016623:Ion Pumps; D009097:Multienzyme Complexes; D020825:T-Box Domain Proteins; D015534:Trans-Activators; D014157:Transcription Factors; D051176:beta Catenin; C071119:SM30 protein, Strongylocentrotus purpuratus; D053501:Arsenite Transporting ATPases; C506972:Asna1 protein, mouse