Maternal Control of Pattern Formation at the Ends of the Drosophila Embryo

果蝇胚胎末端图案形成的母体控制

• 批准号: 0344888
• 负责人: David Stein
• 金额: $ 39万
• 依托单位: University of Texas at Austin
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-04-01 至 2008-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0344888&HistoricalAwards=false
• 关键词: Maternal; Control; Pattern; Formation; Ends

Project SummaryThe mechanisms through which the seemingly simple fertilized egg generates a complex multicellular organism is a topic of fundamental interest that has been pondered since the time of Aristotle. A major insight that has emerged from studies of early development in the fruitfly Drosophila melanogaster is that the generation of pattern in the embryo is dependent upon the prior establishment of pattern in the ovarian follicle in which the egg is formed. The mother fly provisions the developing egg with a set of localized determinants that will later direct the spatially- specific expression of the embryo's own genes. Among the structures that are specified by localized maternal determinants are the most terminally-positioned structures of the Drosophila embryo, the acron at the anterior and the telson at the posterior. Formation of the termini requires activation of the transmembrane receptor tyrosine kinase Torso, which is distributed throughout the membrane of the early embryo. This activation must occur specifically at the ends of the embryo. The ligand for Torso is thought to be the Trunk protein, which is secreted into the fluid-filled perivitelline space that lies between the embryonic membrane and the inner surface of the eggshell, the vitelline membrane. Spatially-restricted activation of Torso by Trunk is believed to be controlled by the product of the gene torsolike. During oogenesis, torsolike is expressed in two specialized groups of polar follicle cells at the anterior and posterior ends of the developing oocyte. Our laboratory has found that Torsolike is localized to the anterior and posterior ends of the eggshell. These observations suggest a mechanism whereby an inactive precursor form of Trunk is secreted uniformly into the perivitelline space and processed into an active ligand specifically at the ends of the egg where it then binds and activates the Torso receptor. Trunk activation requires the function of Torsolike in a process that has not been elucidated. The objectives of this work are to determine the molecular mechanism by which Trunk becomes activated, and to elucidate the role Torsolike protein plays in this process. The specific aims are: (1) To determine whether Trunk is processed from an inactive precursor into an active ligand. (2) To identify other effector molecules involved in the formation of the Trunk ligand by their abilities to interact with Torsolike, and through the characterization of new mutations that affect the specification of the termini. (3 ) To identify the determinants of Torsolike that mediate its localization in the vitelline membrane of the eggshell. Intellectual merit: In addition to their contribution to the understanding of pattern formation in early development these experiments have significance outside of the context of Drosophila early development. Signal transduction through receptor tyrosine kinases is required for a wide variety of cell/cell communication pathways that operate in numerous physiological and developmental contexts, including axonal pathfinding, cell migration, cell differentiation and proliferation. The role of the Drosophila Torso receptor in embryonic patterning is a particularly compelling paradigm because of the exquisite regulation of its activation, both spatially and temporally. The control of Torso activation by its ligand is likely to provide important insights applicable to a variety of other ligand/receptor interactions that are of intellectual, as well as medical interest. Broader impacts resulting from the proposed activity: (1) Discovery, understanding, teaching, training and learning. The maternal control of Drosophila embryonic anterior-posterior polarity is a textbook paradigm that is used in undergraduate teaching of developmental biology. The experiments described herein seek a deeper understanding of this process. Furthermore, the investigations proposed provide numerous opportunities for experimental contributions by undergraduate students at the University of Texas, which will contribute to "hands on" training of those students in a research setting. Interested undergraduate students will be encouraged to participate in this project. These students will have the opportunity to present their work at local and national scientific meetings. Both the graduate student researcher and faculty associates comprising the research team on this proposal will also engage in undergraduate teaching. (2) Participation of underrepresented groups. The University of Texas matriculates a large population of students from historically underrepresented groups. Opportunities for hands on training in laboratory research related to the proposed studies will be available to interested students from these groups. (3) Dissemination of Results. Results obtained will be published in the scientific literature and reported at scientific conferences. Moreover, segments of the proposed investigations involve the generation of reagents likely to be of use to other investigors. These will be disseminated freely to any who request them.

从亚里士多德时代开始，看似简单的受精卵产生复杂的多细胞生物体的机制就一直是人们思考的一个基本问题。对果蝇（Drosophila melanogaster）早期发育的研究得出的一个重要结论是，胚胎中模式的产生取决于卵子形成的卵泡中模式的预先建立。母蝇为发育中的卵提供一组局部化的决定因子，这些决定因子随后将指导胚胎自身基因的空间特异性表达。在由局部母体决定因素指定的结构中，有果蝇胚胎最末端的结构，前部的acron和后部的telson。末端的形成需要跨膜受体酪氨酸激酶Torso的激活，其分布在早期胚胎的整个膜中。这种激活必须特别发生在胚胎的末端。躯干的配体被认为是Trunk蛋白，它分泌到位于胚胎膜和蛋壳内表面（卵黄膜）之间的充满液体的卵黄周间隙中。躯干对躯干的空间限制性激活被认为是由torsolike基因的产物控制的。在卵子发生过程中，torsolike在发育中的卵母细胞的前端和后端的两组专门的极卵泡细胞中表达。我们的实验室发现，Torsolike定位于蛋壳的前端和后端。这些观察结果表明，Trunk的非活性前体形式均匀地分泌到卵周间隙中，并在卵的末端特异性地加工成活性配体，然后结合并激活躯干受体。躯干激活需要Torsolike在一个尚未阐明的过程中发挥作用。这项工作的目的是确定的分子机制，躯干成为激活，并阐明Torsolike蛋白在这一过程中发挥的作用。具体目的是：（1）确定Trunk是否由无活性前体加工成活性配体。(2)通过与Torsolike相互作用的能力以及通过表征影响末端特异性的新突变，鉴定参与Trunk配体形成的其他效应分子。（3）确定介导Torsolike在蛋壳卵黄膜中定位的决定因素。智力优点：除了对理解早期发育模式形成的贡献外，这些实验在果蝇早期发育的背景之外也具有重要意义。通过受体酪氨酸激酶的信号转导是在许多生理和发育环境中操作的多种细胞/细胞通信途径所需的，包括轴突寻路、细胞迁移、细胞分化和增殖。果蝇躯干受体在胚胎模式中的作用是一个特别引人注目的范例，因为它的激活在空间和时间上都有精确的调节。通过其配体控制躯干激活可能提供适用于各种其他配体/受体相互作用的重要见解，这些相互作用具有智力和医学意义。拟议活动产生的更广泛影响：（1）发现、理解、教学、培训和学习。果蝇胚胎前-后极性的母体控制是发育生物学本科教学中使用的教科书范例。本文所述的实验旨在更深入地理解这一过程。此外，建议的调查提供了许多机会，由本科生在得克萨斯大学，这将有助于“动手”的研究设置这些学生的培训实验的贡献。有兴趣的本科生将被鼓励参加这个项目。这些学生将有机会在地方和国家科学会议上展示他们的工作。研究生研究员和教职员工组成的研究小组对这一建议也将从事本科教学。(2)代表性不足群体的参与。德克萨斯大学录取了大量来自历史上代表性不足的群体的学生。来自这些群体的感兴趣的学生将有机会获得与拟议研究有关的实验室研究的实践培训。(3)传播成果。获得的结果将发表在科学文献中，并在科学会议上报告。此外，拟议调查的部分涉及可能对其他生物有用的试剂的产生。这些资料将免费分发给任何提出要求的人。