Yoshida-Kashikawa Maki, Shibata Norito, Takechi Katsuaki, Agata Kiyokazu
RIKEN Center for Developmental Biology, Hyogo, Japan.
Dev Dyn. 2007 Dec;236(12):3436-50. doi: 10.1002/dvdy.21375.
The stem cells of planarians, known as neoblasts, can give rise to all cell types in planarians. Neoblasts can be identified by electron microscopy as cells with electron-dense chromatoid bodies, which are large RNP (ribonucleoprotein) complexes, in their cytoplasm. However, the components and function of chromatoid bodies are still relatively unknown. Here we identified a DEAD box RNA helicase gene of the RCK/p54/Me31B family from a planarian EST database and showed the localization of its product in chromatoid bodies by immunoelectron microscopy. We named this gene Djcbc-1 (Dugesia japonica chromatoid body component 1). Djcbc-1 was also strongly expressed in the brain and in the germline stem cells of sexualized planarians. We observed chromatoid body-like electron-dense bodies in brain neurons, where DjCBC-1 was also expressed. These observations suggest that common molecular components of RNP complexes may be involved in the regulation of somatic and germline stem cells, and neurons in planarians.
涡虫的干细胞，即所谓的新细胞，可以分化成涡虫体内的所有细胞类型。通过电子显微镜观察，新细胞可被鉴定为细胞质中含有电子致密类染色质体的细胞，类染色质体是大型核糖核蛋白（RNP）复合体。然而，类染色质体的组成成分和功能仍相对未知。在此，我们从涡虫EST数据库中鉴定出一个RCK/p54/Me31B家族的DEAD盒RNA解旋酶基因，并通过免疫电子显微镜显示了其产物在类染色质体中的定位。我们将该基因命名为Djcbc-1（日本三角涡虫类染色质体成分1）。Djcbc-1在涡虫的脑和有性生殖涡虫的生殖系干细胞中也有强烈表达。我们在脑神经元中观察到了类似类染色质体的电子致密体，Djcbc-1在这些神经元中也有表达。这些观察结果表明，RNP复合体的共同分子成分可能参与了涡虫体内体细胞、生殖系干细胞和神经元的调控。
