Specification and Patterning of the Animal-Vegetal Axis

动物-植物轴的规范和模式

• 批准号: 0110532
• 负责人: Athula Wikramanayake
• 金额: $ 36万
• 依托单位: University of Hawaii
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2005-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0110532&HistoricalAwards=false
• 关键词: Specification; Patterning; Animal; Vegetal; Axis

0110532WikramanayakeDepletion of nuclear beta-catenin in early sea urchin embryos affects thefates of multiple cell lineages along the animal-vegetal (A/V) axis. It isknown that the micromeres, which form the early signaling center thatspecifies mesendoderm, require nuclear beta-catenin to become competent tocarry out their inductive functions. Beta-catenin signaling is alsorequired in the veg2 lineage for these cells to respond to micromeresignals and to become specified as mesendoderm. Identifyingtranscriptional targets of beta-catenin and elucidating their functionswould be a critical step in defining the molecular basis of mesendodermspecification. This proposal will focus on SUWnt8, a nuclearbeta-catenin-sensitive Wnt gene that is activated in the micromerescoincident with the entry of beta-catenin into the nuclei of these cellsand in the veg2 tier shortly after transit of beta-catenin into the nucleiof this cell tier. Four proposed specific aims will define the function ofSUWnt8 in these cell lineages and will further the understanding ofmesendoderm specification in the sea urchin embryo. These aims are: (1) Todetermine the role of cell interactions in regulating early SUWnt8expression in the mesendoderm domain. This will provide insight into therelative roles of cell autonomous and non cell-autonomous mechanisms inearly mesendoderm specification. (2) To determine how SUWnt8 participatesin early mesendoderm specification by elucidating its role in themicromeres and the veg2 tier by blocking its activity using morpholinoantisense oligonucleotide-mediated translational inhibition. Additionally,a possible role for SUWnt8 in maintaining nuclear beta-catenin levels invegetal cells and in suppressing the activity of animalizing transcriptionfactors in vegetal cells will be determined. (3) While nuclearbeta-catenin is required for normal mesendoderm specification, there isevidence that micromeres can induce mesendoderm in animal half blastomeresin the absence of detectable nuclear beta-catenin. It will be determinedif SUWnt8 can signal through the planar cell polarity pathway via theDisheveled protein to participate in mesendoderm specification in parallelwith the beta-catenin pathway. (4) The unique expression pattern of SUWnt8makes it a powerful reagent for studying the transcriptional basis ofmesendoderm specification. The trans-acting factors that mediate SUWnt8expression in the micromeres and the veg2 tier will be identified.Together, these studies will further our understanding of how the seaurchin A/V axis is specified and patterned and may provide insight intothe evolution of the A/V axis in bilaterians.

在早期海胆胚胎中细胞核β-连环蛋白的缺失会影响沿着动物-植物（A/V）轴的多个细胞谱系的命运。众所周知，微粒形成了指定中内胚层的早期信号中心，需要核β-连环蛋白才能胜任其诱导功能。在veg 2谱系中，β-连环蛋白信号也是这些细胞对微粒体信号做出反应并成为中内胚层所必需的。确定β-连环蛋白的转录靶点并阐明其功能将是确定中内胚层特化的分子基础的关键一步。本研究的重点是SUWnt 8，一种对β-连环蛋白敏感的核Wnt基因，它在β-连环蛋白进入这些细胞的细胞核时在微粒中被激活，并在β-连环蛋白进入细胞核后不久在veg 2层被激活。提出的四个具体目标将定义SUWnt 8在这些细胞谱系中的功能，并将进一步理解海胆胚胎中的中内胚层特化。这些目的是：（1）确定细胞相互作用在调节中内胚层区域SUWnt 8早期表达中的作用。这将有助于深入了解细胞自主和非细胞自主机制在早期中内胚层特化中的相对作用。(2)通过使用吗啉代反义寡核苷酸介导的翻译抑制来阻断SUWnt 8的活性，阐明其在微粒体和veg 2层中的作用，以确定SUWnt 8如何参与早期中内胚层特化。此外，SUWnt 8在维持细胞核β-连环蛋白水平和抑制植物细胞中动物化转录因子活性方面的可能作用也将被确定。(3)虽然核β-连环蛋白是正常的中内胚层特化所必需的，但有证据表明，在缺乏可检测到的核β-连环蛋白的情况下，微粒可以诱导动物半卵裂球中的中内胚层。将确定SUWnt 8是否可以通过Disheveled蛋白通过平面细胞极性途径传递信号，从而与β-连环蛋白途径平行地参与中内胚层特化。(4)SUWnt 8独特的表达模式使其成为研究中内胚层特化转录基础的有力试剂。介导SUWnt 8在微粒体和veg 2层表达的反式作用因子将被鉴定，这些研究将进一步加深我们对海胆A/V轴是如何被指定和模式化的理解，并可能提供对双侧性动物A/V轴进化的深入了解。