Ogawa Kazuya, Kobayashi Chiyoko, Hayashi Tetsutaro, Orii Hidefumi, Watanabe Kenji, Agata Kiyokazu
Laboratory of Regeneration Biology, Department of Life Science, Faculty of Science, Himeji Institute of Technology, Harima Science Garden City, Akou, Hyogo 678-1297, Japan.
Dev Growth Differ. 2002 Jun;44(3):191-204. doi: 10.1046/j.1440-169x.2002.00634.x.
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.
涡虫强大的再生能力被认为存在于一种名为“新胚层”的全能性体细胞干细胞中。然而，调节干细胞分化/生长/迁移的信号系统仍不清楚。成纤维细胞生长因子（FGF）/成纤维细胞生长因子受体（FGFR）系统被认为在脊椎动物和无脊椎动物中都介导各种发育事件。我们研究了DjFGFR1和DjFGFR2这两个与其他动物FGFR基因密切相关的涡虫基因的分子结构和表达。DjFGFR1和DjFGFR2蛋白在细胞外区域分别含有三个和两个免疫球蛋白样结构域，在细胞内区域含有一个分裂的酪氨酸激酶结构域。在完整涡虫的脑神经节和间质空间中观察到DjFGFR1和DjFGFR2的表达。在再生涡虫中，在芽基以及再生咽或脑的片段中观察到表达DjFGFR1的细胞积累。在失去再生能力的X射线照射涡虫中，间质空间中表达DjFGFR1的细胞数量明显减少。这些结果表明，DjFGFR1蛋白可能参与控制涡虫再生的信号系统，如干细胞的分化/生长/迁移等方面。
