ACTIVIN RECEPTORS AND SMAD2 IN MAMMALIAN GASTRULATION

哺乳动物原肠胚形成中的激活素受体和 SMAD2

• 批准号: 6521019
• 负责人: EN LI
• 金额: $ 26.56万
• 依托单位: MASSACHUSETTS GENERAL HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-06-01 至 2004-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6521019
• 关键词: apoptosis; biological signal transduction; bone morphogenetic proteins; cell differentiation; cell growth regulation; cell proliferation; early embryonic stage; gene targeting; genetically modified animals; growth factor receptors; histogenesis; hormone regulation /control mechanism; in situ hybridization; laboratory mouse; mammalian embryology; mesoderm; microinjections; protein structure function; tissue /cell culture; transforming growth factors

The transforming growth factor-beta (TGF-beta) superfamily molecules play critical roles in a diverse range of developmental processes. Our long term goal is to understand the signaling mechanism by which TGF-beta family factors regulate morphogenesis. Mesoderm induction and gastrulation are key events that lead to the establishment of body axes. Members of the TGF-beta family such as activins, Vg-1, nodal, and BMPs are potent mesoderm inducing factors and function during early development in vertebrate animals. The signaling cascade and the developmental program activated by activin or BMP has been extensively studied in Xenopus and chick early embryos. However, it remains unclear whether these signaling pathways are conserved in mammals. Genetic studies have demonstrated that nodal and BMP4, but not zygotic activins, are essential for early mouse development. To investigate the function of activin type I and type II receptors and a downstream signal mediator Smad2 in mammalian development, mutant mice have been generated by targeted disruption of the corresponding genes in mice. Genetic and embryological studies of the mutant mice have provided direct evidence that activin receptors and Smad2 are essential for mesoderm formation and gastrulation. To further analyze the function of activin receptor- and Smad2- mediated signaling pathways in the regulation of cell growth and differentiation, primitive streak formation and gastrulation, the following specific aims are proposed: (1) To understand how activin receptors and Smad2 regulate embryo growth, germ layer organization, and cell fate determination during egg cylinder formation and gastrulation. (2) To investigate how activin receptors and Smad2 regulate primitive streak formation and mesoderm patterning. 3) To investigate the function of nodal, BMP4, and chordin and their signaling pathways in primitive streak formation. Methods such as chimera (or mosaic) analysis through microinjection of blastocysts or aggregation of tetraploid embryos with ES cells, in situ hybridization, lineage analysis with lacZ-marked mutant ES cells, and ES cell-mediated gene delivery will be applied in this project. These aims, once accomplished, will lead to a better understanding of the signaling mechanism that controls early mammalian development. The knowledge acquired regarding early embryonic development will be useful for understanding later developmental processes such as organogenesis and will have important implications towards understanding the genetic basis of various forms of birth defects in human.

转化生长因子-β（TGF-β）超家族分子在多种发育过程中发挥关键作用。 我们的长期目标是了解TGF-β家族因子调节形态发生的信号机制。 中胚层诱导和原肠胚形成是导致体轴建立的关键事件。 TGF-β家族的成员如激活素、Vg-1、nodal和BMP是有效的中胚层诱导因子，并在脊椎动物的早期发育过程中发挥作用。 激活素或BMP激活的信号级联和发育程序已在非洲爪蟾和鸡早期胚胎中被广泛研究。 然而，目前还不清楚这些信号通路是否在哺乳动物中是保守的。 遗传研究表明，nodal和BMP 4，而不是合子激活素，是小鼠早期发育所必需的。 为了研究激活素I型和II型受体以及下游信号介体Smad 2在哺乳动物发育中的功能，通过靶向破坏小鼠中相应的基因来产生突变小鼠。 对突变小鼠的遗传学和胚胎学研究提供了直接证据，表明激活素受体和Smad 2对中胚层形成和原肠胚形成至关重要。 为了进一步分析激活素受体和Smad 2介导的信号通路在调控细胞生长和分化、原条形成和原肠胚形成中的作用，本文提出了以下具体目标：（1）了解激活素受体和Smad 2如何调控胚胎生长、胚层组织和细胞命运决定。 (2)研究激活素受体和Smad 2如何调节原条形成和中胚层模式化。 3)探讨nodal、BMP 4和chordin在原条形成中的作用及其信号通路。 本项目将采用显微注射囊胚或四倍体胚胎与ES细胞聚集的嵌合体（或嵌合体）分析、原位杂交、lacZ标记的突变ES细胞谱系分析以及ES细胞介导的基因递送等方法。 这些目标一旦实现，将导致更好地了解控制早期哺乳动物发育的信号机制。获得有关早期胚胎发育的知识将有助于了解后来的发育过程，如器官发生，并将对了解人类各种形式的出生缺陷的遗传基础具有重要意义。