Wnt5 is required for notochord cell intercalation in the ascidian Halocynthia roretzi.
Wnt5 is required for notochord cell intercalation in the ascidian Halocynthia roretzi.
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DOI：
10.1042/bc20090042
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发表时间：
2009-08-25
影响因子：
2.7
通讯作者：
Nishida H
中科院分区：
文献类型：
--
作者：
Niwano T;Takatori N;Kumano G;Nishida H
背景资料。在各种动物的胚胎中，原肠胚形成后，身体通过包括会聚延伸的形态发生运动而伸长。Wnt/PCP（planar cell polarity）途径在这一过程中发挥作用，特别是胚胎细胞的中外侧极化和嵌入。在海鞘中，已经鉴定了该途径中的几个因子，包括Wnt 5，并发现其参与脊索细胞的嵌入过程。结果本研究以海鞘H. roretzi（Halocynthia roretzi）为材料，研究了Wnt 5基因Hr-Wnt 5 α和Hr-Wnt 5 β在海鞘H. roretzi通过注射反义寡核苷酸和mRNA到单个前体卵裂球的各种组织，包括脊索，在64细胞阶段。Hr-Wnt 5 α在发育中的脊索中表达，并且是脊索形态发生所必需的。其表达水平的精确定量控制对于适当的细胞嵌入至关重要。Wnt 5蛋白在脊索和脊索周围的其他组织中的过表达表明Wnt 5 α在脊索内起作用，并且不太可能是脊索外产生的极化线索的来源。对过表达Wnt 5 α的单个脊索细胞行为的详细镶嵌分析表明，Wnt 5 α操纵的细胞不会影响相邻脊索细胞的行为，这表明Wnt 5 α以细胞自主的方式工作。Wnt 5 α和Dsh（Dishevelled）敲低实验结果的比较进一步支持了这一点。此外，我们的研究结果表明，Wnt/PCP通路也参与了神经索（底板）和内胚层链的腹侧行细胞的中外侧嵌入。结论本研究强调了Wnt 5 α信号在海鞘胚胎脊索会聚延伸运动中的作用。我们的研究结果提出了一种新的可能性，即Wnt 5 α以细胞自主的方式激活Wnt/PCP通路，以抑制驱动会聚延伸的伸展活性。
Background information. In the embryos of various animals, the body elongates after gastrulation by morphogenetic movements involving convergent extension. The Wnt/PCP (planar cell polarity) pathway plays roles in this process, particularly mediolateral polarization and intercalation of the embryonic cells. In ascidians, several factors in this pathway, including Wnt5, have been identified and found to be involved in the intercalation process of notochord cells. Results. In the present study, the role of the Wnt5 genes, Hr-Wnt5α (Halocynthia roretzi Wnt5α) and Hr-Wnt5β, in convergent extension was investigated in the ascidian H. roretzi by injecting antisense oligonucleotides and mRNAs into single precursor blastomeres of various tissues, including notochord, at the 64-cell stage. Hr-Wnt5α is expressed in developing notochord and was essential for notochord morphogenesis. Precise quantitative control of its expression level was crucial for proper cell intercalation. Overexpression of Wnt5 proteins in notochord and other tissues that surround the notochord indicated that Wnt5α plays a role within the notochord, and is unlikely to be the source of polarizing cues arising outside the notochord. Detailed mosaic analysis of the behaviour of individual notochord cells overexpressing Wnt5α indicated that a Wnt5α-manipulated cell does not affect the behaviour of neighbouring notochord cells, suggesting that Wnt5α works in a cell-autonomous manner. This is further supported by comparison of the results of Wnt5α and Dsh (Dishevelled) knockdown experiments. In addition, our results suggest that the Wnt/PCP pathway is also involved in mediolateral intercalation of cells of the ventral row of the nerve cord (floor plate) and the endodermal strand. Conclusion. The present study highlights the role of the Wnt5α signal in notochord convergent extension movements in ascidian embryos. Our results raise the novel possibility that Wnt5α functions in a cell-autonomous manner in activation of the Wnt/PCP pathway to polarize the protrusive activity that drives convergent extension.