title: Planarian fibroblast growth factor receptor homologs expressed in stem cells and cephalic ganglions.
abstract: The strong regenerative capacity of planarians is considered to reside in the totipotent somatic stem cell called the 'neoblast'. However, the signal systems regulating the differentiation/growth/migration of stem cells remain unclear. The fibroblast growth factor (FGF)/FGF receptor (FGFR) system is thought to mediate various developmental events in both vertebrates and invertebrates. We examined the molecular structures and expression of DjFGFR1 and DjFGFR2, two planarian genes closely related to other animal FGFR genes. DjFGFR1 and DjFGFR2 proteins contain three and two immunoglobulin-like domains, respectively, in the extracellular region and a split tyrosine kinase domain in the intracellular region. Expression of DjFGFR1 and DjFGFR2 was observed in the cephalic ganglion and mesenchymal space in intact planarians. In regenerating planarians, accumulation of DjFGFR1-expressing cells was observed in the blastema and in fragments regenerating either a pharynx or a brain. In X-ray-irradiated planarians, which had lost regenerative capacity, the number of DjFGFR1-expressing cells in the mesenchymal space decreased markedly. These results suggest that the DjFGFR1 protein may be involved in the signal systems controlling such aspects of planarian regeneration as differentiation/growth/migration of stem cells.
authors.affiliation: Laboratory of Regeneration Biology, Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Akou, Hyogo 678-1297, Japan.
authors.forename: Kazuya
authors.initials: K
authors.lastname: Ogawa
authors.forename: Chiyoko
authors.initials: C
authors.lastname: Kobayashi
authors.forename: Tetsutaro
authors.initials: T
authors.lastname: Hayashi
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Orii
authors.forename: Kenji
authors.initials: K
authors.lastname: Watanabe
authors.forename: Kiyokazu
authors.initials: K
authors.lastname: Agata
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D018509:DNA, Helminth; D017952:Ganglia, Invertebrate / Q000378:metabolism*; D020869:Gene Expression Profiling; D008969:Molecular Sequence Data; D010932:Planarians / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D017434:Protein Structure, Tertiary; D034622:RNA Interference; D020794:Receptor Protein-Tyrosine Kinases / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2; D017468:Receptors, Fibroblast Growth Factor / Q000235:genetics* / Q000378:metabolism / Q000528:radiation effects; D012038:Regeneration / Q000235:genetics; D013234:Stem Cells / Q000378:metabolism*; D014965:X-Rays
chemical_list: D018509:DNA, Helminth; D017468:Receptors, Fibroblast Growth Factor; D020794:Receptor Protein-Tyrosine Kinases; D051496:Receptor, Fibroblast Growth Factor, Type 1; D051497:Receptor, Fibroblast Growth Factor, Type 2