Blastocoel-spanning filopodia in cleavage-stage Xenopus laevis: Potential roles in morphogen distribution and detection
Blastocoel-spanning filopodia in cleavage-stage Xenopus laevis: Potential roles in morphogen distribution and detection
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DOI：
10.1016/j.ydbio.2013.07.024
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发表时间：
2013-10-01
影响因子：
2.7
通讯作者：
Brown, Elizabeth
中科院分区：
文献类型：
--
作者：
Danilchik, Michael;Williams, Melissa;Brown, Elizabeth
在青蛙非洲爪蟾，背腹轴规范涉及在第一个细胞周期中的局部转录本和蛋白质的依赖于细胞因子的运输，和经典Wnt途径的激活，以局部稳定翻译的β-连环蛋白，早在32细胞阶段，提交核在未来的背侧谱系的背侧靶基因的后续表达。母体配体激活这一背特异性信号通路的重要性被认为是相互作用的分泌磷脂酰肌醇蛋白聚糖和辅助受体的囊胚腔。虽然细胞之间的扩散通常被认为足以实现分泌的母体配体向其适当靶标的分布，但信号传导也可能涉及其他潜在机制，包括通过膜结合实体（如argosome、外泌体或甚至丝状伪足）直接转移形态发生剂。在异种脓中，信号相互作用表面上发生的面向囊胚腔的基底外侧表面以前没有被详细研究过。在这里，我们报告说，卵裂阶段的囊胚腔是由数百个非常长的细胞突起，保持长期接触不相邻的卵裂球在早期胚胎发生的间隙空间的扩张过程中穿过。这些突起参与早期胚胎的形成是由以下发现提出的：（a）它们碎裂成微泡，微泡的再吸收促进卵裂球之间的细胞质和膜的大量交换;和（B）它们在小窝内吞中是活跃的，这是配体-受体信号传导的先决条件。(C)2013 Elsevier Inc. All rights reserved.
In the frog Xenopus laevis, dorsal ventral axis specification involves cytoskeleton-dependent transport of localized transcripts and proteins during the first cell cycle, and activation of the canonical Wnt pathway to locally stabilize translated beta-catenin which, by as early as the 32-cell stage, commits nuclei in prospective dorsal lineages to the subsequent expression of dorsal target genes. Maternal ligands important for activating this dorsal-specific signaling pathway are thought to interact with secreted glypicans and coreceptors in the blastocoel. While diffusion between cells is generally thought of as sufficient to accomplish the distribution of secreted maternal ligands to their appropriate targets, signaling may also involve other potential mechanisms, including direct transfer of morphogens via membrane-bounded entities, such as argosomes, exosomes, or even filopodia. In Xeno pus, the blastocoel-facing, basolateral surfaces where signaling interactions ostensibly take place have not been previously examined in detail. Here, we report that the cleavage-stage blastocoel is traversed by hundreds of extremely long cellular protrusions that maintain long-term contacts between nonadjacent blastomeres during expansion of the interstitial space in early embryogenesis. The involvement of these protrusions in early embryonic patterning is suggested by the discoveries that (a) they fragment into microvesicles, whose resorption facilitates considerable exchange of cytoplasm and membrane between blastomeres; and (b) they are active in caveolar endocytosis, a prerequisite for ligand-receptor signaling. (C) 2013 Elsevier Inc. All rights reserved.