Agata Kiyokazu, Umesono Yoshihiko
Department of Biophysics, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwake, Sakyo-ku, Kyoto 606-8502, Japan.
Philos Trans R Soc Lond B Biol Sci. 2008 Jun 27;363(1500):2071-8. doi: 10.1098/rstb.2008.2260.
How can planarians regenerate their brain? Recently we have identified many genes critical for this process. Brain regeneration can be divided into five steps: (1) anterior blastema formation, (2) brain rudiment formation, (3) pattern formation, (4) neural network formation, and (5) functional recovery. Here we will describe the structure and process of regeneration of the planarian brain in the first part, and then introduce genes involved in brain regeneration in the second part. Especially, we will speculate about molecular events during the early steps of brain regeneration in this review. The finding providing the greatest insight thus far is the discovery of the nou-darake (ndk; 'brains everywhere' in Japanese) gene, since brain neurons are formed throughout the entire body as a result of loss of function of the ndk gene. This finding provides a clue for elucidating the molecular and cellular mechanisms underlying brain regeneration. Here we describe the molecular action of the nou-darake gene and propose a new model to explain brain regeneration and restriction in the head region of the planarians.
涡虫是如何再生其大脑的？最近我们已经鉴定出许多对这一过程至关重要的基因。大脑再生可分为五个步骤：（1）前部芽基形成，（2）脑原基形成，（3）模式形成，（4）神经网络形成，以及（5）功能恢复。在此，我们将在第一部分描述涡虫大脑再生的结构和过程，然后在第二部分介绍参与大脑再生的基因。特别是，在本综述中我们将推测大脑再生早期阶段的分子事件。迄今为止最具启发性的发现是nou-darake（ndk；日语意为“到处都是大脑”）基因的发现，因为由于ndk基因功能丧失，脑神经元在全身各处形成。这一发现为阐明大脑再生的分子和细胞机制提供了线索。在此我们描述nou-darake基因的分子作用，并提出一个新模型来解释涡虫大脑再生及头部区域的限制。
