title: Expression and function of myc during asexual reproduction of the budding ascidian Polyandrocarpa misakiensis.
abstract: The budding ascidian Polyandrocarpa misakiensis proliferates asexually by budding. The atrial epithelium is a multipotent but differentiated tissue, which transdifferentiates into various tissues and organs after the bud separates from the parental body. We isolated cDNA clones homologous to the myc proto-oncogene from P. misakiensis. The cDNA, named Pm-myc, encoded a polypeptide of 639 amino acid residues, containing Myc-specific functional motifs, Myc box I and Myc box II, and the basic helix-loop-helix domain. Expression of Pm-myc was observed in the atrial epithelium in the organ-forming region of the developing bud, where the epithelial cells dedifferentiate and re-enter the cell cycle. The expression was also observed in fibroblast-like cells, which are known to participate in the organogenesis together with the epithelial cells. Unexpectedly, the atrial epithelium expressed Pm-myc more than one day before the dedifferentiation. The organogenesis was disturbed by Pm-myc-specific double-stranded RNA. In situ hybridization revealed that Pm-myc-positive fibroblast-like cells disappeared around the organ primordium of the dsRNA-treated bud. The results suggest that the mesenchymal-epithelial transition of fibroblast-like cells is important for the organogenesis in this budding ascidian species.
authors.affiliation: Department of Applied Science, Kochi University, 2-5-1 Akebono-cho, Kochi-shi, Kochi 780-8520, Japan. tatataa@kochi-u.ac.jp
authors.forename: Shigeki
authors.initials: S
authors.lastname: Fujiwara
authors.forename: Takaomi
authors.initials: T
authors.lastname: Isozaki
authors.forename: Kyoko
authors.initials: K
authors.lastname: Mori
authors.forename: Kazuo
authors.initials: K
authors.lastname: Kawamura
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000235:genetics; D018076:DNA, Complementary; D059630:Mesenchymal Stem Cells / Q000378:metabolism; D038081:Organogenesis; D010802:Phylogeny; D016271:Proto-Oncogene Proteins c-myc / Q000096:biosynthesis / Q000235:genetics*; D034622:RNA Interference; D034741:RNA, Small Interfering; D012100:Reproduction, Asexual / Q000235:genetics; D014561:Urochordata / Q000166:cytology / Q000235:genetics* / Q000378:metabolism / Q000502:physiology*
chemical_list: D018076:DNA, Complementary; D016271:Proto-Oncogene Proteins c-myc; D034741:RNA, Small Interfering