title: A LIM-homeobox gene is required for differentiation of Wnt-expressing cells at the posterior end of the planarian body.
abstract: Planarians have high regenerative ability, which is dependent on pluripotent adult somatic stem cells called neoblasts. Recently, canonical Wnt/β-catenin signaling was shown to be required for posterior specification, and Hedgehog signaling was shown to control anterior-posterior polarity via activation of the Djwnt1/P-1 gene at the posterior end of planarians. Thus, various signaling molecules play an important role in planarian stem cell regulation. However, the molecular mechanisms directly involved in stem cell differentiation have remained unclear. Here, we demonstrate that one of the planarian LIM-homeobox genes, Djislet, is required for the differentiation of Djwnt1/P-1-expressing cells from stem cells at the posterior end. RNA interference (RNAi)-treated planarians of Djislet [Djislet(RNAi)] show a tail-less phenotype. Thus, we speculated that Djislet might be involved in activation of the Wnt signaling pathway in the posterior blastema. When we carefully examined the expression pattern of Djwnt1/P-1 by quantitative real-time PCR during posterior regeneration, we found two phases of Djwnt1/P-1 expression: the first phase was detected in the differentiated cells in the old tissue in the early stage of regeneration and then a second phase was observed in the cells derived from stem cells in the posterior blastema. Interestingly, Djislet is expressed in stem cell-derived DjPiwiA- and Djwnt1/P-1-expressing cells, and Djislet(RNAi) only perturbed the second phase. Thus, we propose that Djislet might act to trigger the differentiation of cells expressing Djwnt1/P-1 from stem cells.
authors.affiliation: Genome Resource and Analysis Unit, RIKEN Center for Developmental Biology, 2-2-3 Minatojima-minamimachi, Chuo-ku, Kobe, Hyogo 650-0047, Japan. t-hayashi88@cdb.riken.jp
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Hayashi
authors.forename: Minako
authors.initials: M
authors.lastname: Motoishi
authors.forename: Shigenobu
authors.initials: S
authors.lastname: Yazawa
authors.forename: Kazu
authors.initials: K
authors.lastname: Itomi
authors.forename: Chiharu
authors.initials: C
authors.lastname: Tanegashima
authors.forename: Osamu
authors.initials: O
authors.lastname: Nishimura
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tarui
mesh_terms: D000818:Animals; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental / Q000235:genetics / Q000502:physiology; D018398:Homeodomain Proteins / Q000235:genetics / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D010932:Planarians / Q000166:cytology / Q000235:genetics / Q000378:metabolism* / Q000502:physiology*; D034622:RNA Interference; D012038:Regeneration / Q000235:genetics / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D051153:Wnt Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D018398:Homeodomain Proteins; D014157:Transcription Factors; D051153:Wnt Proteins