Hojo Motoki, Takashima Shigeo, Kobayashi Daisuke, Sumeragi Akira, Shimada Atsuko, Tsukahara Tatsuya, Yokoi Hayato, Narita Takanori, Jindo Tomoko, Kage Takahiro, Kitagawa Tadao, Kimura Tetsuaki, Sekimizu Koshin, Miyake Akimitsu, Setiamarga Davin, Murakami Ryohei, Tsuda Sachiko, Ooki Shinya, Kakihara Ken, Naruse Kiyoshi, Takeda Hiroyuki
Department of Biological Sciences, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
Dev Growth Differ. 2007 Jun;49(5):395-405. doi: 10.1111/j.1440-169X.2007.00937.x.
Recent studies have revealed that a cilium-generated liquid flow in the node has a crucial role in the establishment of the left-right (LR) axis in the mouse. In fish, Kupffer's vesicle (KV), a teleost-specific spherical organ attached to the tail region, is known to have an equivalent role to the mouse node during LR axis formation. However, at present, there has been no report of an asymmetric gene expressed in KV under the control of fluid flow. Here we report the earliest asymmetric gene in teleost KV, medaka charon, and its regulation. Charon is a member of the Cerberus/DAN family of proteins, first identified in zebrafish. Although zebrafish charon was reported to be symmetrically expressed in KV, medaka charon displays asymmetric expression with more intense expression on the right side. This asymmetric expression was found to be regulated by KV flow because symmetric and up-regulated charon expression was observed in flow-defective embryos with immotile cilia or disrupted KV. Taken together, medaka charon is a reliable gene marker for LR asymmetry in KV and thus, will be useful for the analysis of the early steps downstream of the fluid flow.
最近的研究表明，在小鼠中，节点处由纤毛产生的液体流动在左右（LR）轴的建立中起着关键作用。在鱼类中，库普弗小泡（KV）是一种附着在尾部区域的硬骨鱼特有的球形器官，已知在LR轴形成过程中与小鼠的节点具有同等作用。然而，目前尚无关于在液体流动控制下KV中表达的不对称基因的报道。在此，我们报告了硬骨鱼KV中最早的不对称基因——青鳉Charon及其调控机制。Charon是Cerberus/DAN蛋白家族的成员，最初在斑马鱼中被鉴定出来。尽管据报道斑马鱼Charon在KV中对称表达，但青鳉Charon表现出不对称表达，右侧表达更强烈。发现这种不对称表达受KV流动调控，因为在具有不动纤毛或KV破坏的流动缺陷胚胎中观察到对称且上调的Charon表达。综上所述，青鳉Charon是KV中LR不对称的可靠基因标记，因此将有助于分析液体流动下游的早期步骤。
