Connexin26-mediated transfer of laterality cues in Xenopus
Connexin26-mediated transfer of laterality cues in Xenopus
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DOI：
10.1242/bio.2012760
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发表时间：
2012-05-15
期刊：
影响因子：
2.4
通讯作者：
Blum, Martin
中科院分区：
文献类型：
--
作者：
Beyer, Tina;Thumberger, Thomas;Blum, Martin
纤毛驱动的细胞外液向左流动打破了神经胚阶段脊椎动物胚胎背侧中线的双边对称性。侧板中胚层 (LPM) 中的左侧特异性 Nodal 信号级联是后续发育过程中不对称形态发生和器官放置的关键。最初的不对称线索的性质以及从中线到左侧的信息传递仍然难以捉摸。间隙连接通讯先前已参与爪蟾左右（LR）发育，但从抑制剂实验推断出分裂阶段的功能。在这里，我们通过庚醇介导的连接蛋白功能阻断表明，神经形成期间的流动阶段代表了关键时间窗口。非洲爪蟾的流动发生在胃腔顶板（GRP）处，胃腔顶板是中胚层细胞的纤毛鞘，短暂地位于形成的弓肠的背侧上皮衬里内。我们推断紧邻 GRP 的内胚层细胞对于不对称性的转移很重要。系统筛选鉴定出两个连接蛋白基因，Cx26 和 Cx32，它们在这些外侧内胚层细胞中共表达。功能获得和丧失实验确定 Cx26 是 LR 发育的关键连接蛋白，而 Cx32 对侧向性没有影响。重要的是，Cx26 变形体中的 GRP 形态、纤毛和流动不受影响。我们的结果证明了 Cx26 在将侧向线索从 GRP 转移到左 LPM 中的决定性作用，为识别血流产生的初始不对称信号提供了一种新的途径。 (C) 2012。由生物学家有限公司出版。
A cilia-driven leftward flow of extracellular fluid breaks bilateral symmetry in the dorsal midline of the neurula stage vertebrate embryo. The left-specific Nodal signaling cascade in the lateral plate mesoderm (LPM) is key to asymmetric morphogenesis and placement of organs during subsequent development. The nature of the initial asymmetric cue(s) as well as the transfer of information from the midline to the left side has remained elusive. Gap junctional communication has been previously involved in Xenopus left-right (LR) development, however a function at cleavage stages was inferred from inhibitor experiments. Here we show by heptanol-mediated block of connexin function that flow stages during neurulation represent the critical time window. Flow in Xenopus occurs at the gastrocoel roof plate (GRP), a ciliated sheath of cells of mesodermal fate transiently positioned within the dorsal epithelial lining of the forming archenteron. We reasoned that endodermal cells immediately adjacent to the GRP are important for transfer of asymmetry. A systematic screen identified two connexin genes, Cx26 and Cx32, which were co-expressed in these lateral endodermal cells. Gain- and loss-of-function experiments pinpointed Cx26 as the critical connexin for LR development, while Cx32 had no effect on laterality. Importantly, GRP morphology, ciliation and flow were not affected in Cx26 morphants. Our results demonstrate a decisive role of Cx26 in the transfer of laterality cues from the GRP to the left LPM, providing a novel access to the identification of the initial asymmetric signal generated by flow. (C) 2012. Published by The Company of Biologists Ltd.