Morphogenesis of mammalian gut endoderm

哺乳动物肠道内胚层的形态发生

• 批准号: 7903433
• 负责人: ANNA-KATERINA HADJANTONAKIS
• 金额: $ 44.41万
• 依托单位: SLOAN-KETTERING INST CAN RESEARCH
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7903433
• 关键词: Adult; Bladder; Cell Differentiation process; Cells; Complex; Conceptus; Defect; Development; Disease Progression; Ectoderm; Embryo; Endoderm; Endoderm Cell; Epiblast; Event; Exhibits; Extraembryonic Structure; Fetal Tissues; Gastrointestinal tract structure; Gastrula; Genetic; Germ Layers; Green Fluorescent Proteins; Image; Image Analysis; Imaging Techniques; Intestines; Knowledge; Label; Life; Liver; Lung; Mammals; Maps; Mediating; Mesoderm; Modeling; Molecular; Morphogenesis; Mus; Organ; Pancreas; Placenta; Play; Population; Proteins; Reporter; Role; Signal Transduction; Staging; Stomach; Structure; Testing; Thymus Gland; Thyroid Gland; Tissues; Tube; Visceral; Yolk Sac; body system; cell behavior; cell motility; cell type; design; embryo tissue; gastrulation; mutant; novel; novel therapeutics; public health relevance; respiratory; segregation

DESCRIPTION (provided by applicant): The gut endoderm gives rise to the major cell types of many internal organs, including the thyroid, thymus, lung, stomach, liver, pancreas, intestine and bladder. A rigorous understanding of normal gut endoderm morphogenesis, including knowledge of the origin, commitment, specification and differentiation of cells generating gut endoderm and its derivative tissues, should underpin logical efforts to understand disease progression and design new therapeutic strategies for these vital organ systems. The prevailing view of germ layer formation in mammalian embryos is that ectoderm, mesoderm and gut endoderm derive solely from the epiblast during gastrulation and while extraembryonic tissues interact with the epiblast to establish the body axes, they contribute solely to extraembryonic structures, such as the yolk sac and placenta. The cell movements underlying the morphogenesis of the gut endoderm, the tissue that gives rise to the respiratory and digestive tracts and associated organs such as the lungs, liver and pancreas, are complex and not well understood. Using live imaging combined with genetic labeling, we have begun to investigate the role of the visceral endoderm, a presumed extraembryonic tissue, in gut endoderm formation in the mouse (Figure 1). Three key findings arise from our preliminary studies. (1) A new model for gut endoderm morphogenesis in the mouse, incorporating a novel morphogenetic mechanism resulting in extensive mixing of embryonic and extraembryonic cells. (2) The stereotypical congregation of extraembryonic (visceral) endoderm cells around signaling centers of the gastrula stage embryo. (3) The segregation of extraembryonic and embryonic tissues, a fundamental feature of mammalian development, may not be as strict as believed, and the visceral endoderm, a lineage defined as exclusively extraembryonic, may contribute cells to the embryo-proper. These questions will be explored in the following three Specific Aims. Figure 1: Combining live imaging and genetics in mice to investigate gut endoderm formation in mammals. Live imaging and genetic labeling of the visceral endoderm, and its derivatives in mouse embryos. At embryonic day (E) 6.5 the entire visceral endoderm is labeled with a green fluorescent protein (GFP) reporter. GFP protein reveals a dispersed population of visceral endoderm-derived cells present in the embryonic region of the conceptus at E7.5, which by E8.75 become incorporated into the gut tube of the embryo (A,B). Specific Aim 1: To elucidate the cell behaviors that mediate gut endoderm morphogenesis. We will use both existing and new reporter strains to visualize cell dynamics in wild type embryos and mutants that exhibit endoderm defects. Specific Aim 2: To determine the sequence of events leading to the organization of extraembryonic (visceral) endoderm cells around signaling centers of the mouse gastrula, and test the hypothesis that this arrangement is central to the function of these signaling centers. This will be achieved using live imaging and the analysis of mutants that fail to generate midline structures. Specific Aim 3: To determine if a lineage relationship exists between the visceral endoderm and the gut endoderm tissues of the fetus and adult mouse. We will establish if the visceral endoderm is a transient or stable component of embryonic and adult gut endoderm derived tissues. We will test the hypothesis that extraembryonic (visceral) endoderm is not an exclusively extraembryonic tissue using a genetic induced fate mapping approach. PUBLIC HEALTH RELEVANCE: The gut endoderm gives rise to the major cell types of many internal organs, including the thyroid, thymus, lung, stomach, liver, pancreas, intestine and bladder. A rigorous understanding of normal gut endoderm morphogenesis, including knowledge of the origin, commitment, specification and differentiation of cells generating gut endoderm and its derivative tissues, should underpin logical efforts to design new therapeutic strategies for this vital organ system. The prevailing view of germ layer formation in mammalian embryos is that ectoderm, mesoderm and gut endoderm derive solely from the pluripotent epiblast during gastrulation, and while extraembryonic tissues interact with the epiblast to establish the body axes, they contribute solely to extraembryonic structures, such as the yolk sac and placenta. Our preliminary studies challenge this view, and inform the hypotheses to be tested through the Specific Aims of this proposal. Three key findings arise from our preliminary studies in mice. (1) A new model for gut endoderm formation in the mouse, incorporating a novel morphogenetic mechanism resulting in extensive mixing of embryonic and extraembryonic cells. (2) The stereotypical congregation of extraembryonic (visceral) endoderm cells around signaling centers of the gastrula stage embryo. (3) The segregation of extraembryonic and embryonic tissues, a fundamental feature of mammalian development, may not be as strict as believed, and the visceral endoderm, a lineage defined as exclusively extraembryonic, may contribute cells to the embryo-proper. The broad aim of this project is to use a combination of molecular, embryological and live imaging techniques to investigate the role played by the visceral endoderm, a presumed extraembryonic lineage, in the morphogenesis of the mammalian gut endoderm, the tissue that will give rise to the respiratory and digestive tracts, and associated organs such as lungs, liver and pancreas. In Aim 1, we will define the cell behaviors that mediate gut endoderm morphogenesis in the embryo. We will use both existing and new reporter strains to visualize cell dynamics in wild type embryos and mutants that exhibit endoderm defects. In Aim 2, we will determine the sequence of events leading to the organization of extraembryonic (visceral) endoderm cells around signaling centers of the mouse gastrula, and test the hypothesis that this arrangement is central to the function of these signaling centers. This will be achieved using live imaging and the analysis of mutants that fail to generate midline structures. In Aim 3, we will determine if a lineage relationship exists between the visceral endoderm and the gut endoderm tissues of the fetus and adult mouse. We will establish if the visceral endoderm is a transient or stable component of embryonic and adult gut endoderm derived tissues, and will test the hypothesis that extraembryonic (visceral) endoderm is not an exclusively extraembryonic tissue using a genetic induced fate mapping approach.

描述（由申请人提供）：肠道内胚层产生许多内脏器官的主要细胞类型，包括甲状腺、胸腺、肺、胃、肝脏、胰腺、肠和膀胱。对正常肠道内胚层形态发生的严格理解，包括对产生肠道内胚层及其衍生组织的细胞的起源、承诺、规范和分化的了解，应该支持理解疾病进展和为这些重要器官系统设计新的治疗策略的逻辑努力。关于哺乳动物胚胎中胚层形成的普遍观点是，外胚层、中胚层和肠内胚层仅源自原肠胚形成期间的外胚层，而胚外组织与外胚层相互作用以建立体轴，但它们仅对胚外结构（例如卵黄）做出贡献。囊和胎盘。肠道内胚层（产生呼吸道和消化道以及相关器官（如肺、肝脏和胰腺）的组织）形态发生背后的细胞运动非常复杂，目前尚不清楚。利用实时成像与基因标记相结合，我们开始研究内脏内胚层（一种推测的胚外组织）在小鼠肠道内胚层形成中的作用（图 1）。我们的初步研究得出了三个关键发现。 (1) 小鼠肠道内胚层形态发生的新模型，结合了一种新的形态发生机制，导致胚胎和胚胎外细胞的广泛混合。 (2)原肠胚阶段胚胎信号中心周围的胚外（内脏）内胚层细胞的典型聚集。 (3) 胚胎外组织和胚胎组织的分离是哺乳动物发育的基本特征，但可能并不像人们认为的那么严格，而内脏内胚层（一种被定义为完全胚胎外的谱系）可能为胚胎本身提供细胞。这些问题将在以下三个具体目标中进行探讨。图 1：结合小鼠的实时成像和遗传学来研究哺乳动物肠道内胚层的形成。小鼠胚胎内脏内胚层及其衍生物的实时成像和基因标记。在胚胎第 (E) 6.5 天，整个内脏内胚层用绿色荧光蛋白 (GFP) 报告基因标记。 GFP 蛋白揭示了在 E7.5 时孕体胚胎区域中存在内脏内胚层衍生细胞的分散群体，这些细胞在 E8.75 时融入胚胎的肠管中 (A,B)。具体目标 1：阐明介导肠道内胚层形态发生的细胞行为。我们将使用现有的和新的报告菌株来可视化野生型胚胎和表现出内胚层缺陷的突变体中的细胞动态。具体目标 2：确定导致小鼠原肠胚信号中心周围胚胎外（内脏）内胚层细胞组织的事件顺序，并检验这种排列对于这些信号中心功能至关重要的假设。这将通过实时成像和对无法生成中线结构的突变体的分析来实现。具体目标 3：确定胎儿和成年小鼠的内脏内胚层和肠道内胚层组织之间是否存在谱系关系。我们将确定内脏内胚层是否是胚胎和成人肠道内胚层衍生组织的短暂或稳定成分。我们将使用遗传诱导的命运图谱方法来检验胚胎外（内脏）内胚层并非完全是胚胎外组织的假设。 公共卫生相关性：肠道内胚层产生许多内脏器官的主要细胞类型，包括甲状腺、胸腺、肺、胃、肝脏、胰腺、肠和膀胱。对正常肠道内胚层形态发生的严格理解，包括对产生肠道内胚层及其衍生组织的细胞的起源、承诺、规范和分化的了解，应该支持为这一重要器官系统设计新的治疗策略的逻辑努力。关于哺乳动物胚胎中胚层形成的普遍观点是，外胚层、中胚层和肠内胚层仅源自原肠胚形成期间的多能外胚层，虽然胚外组织与外胚层相互作用以建立身体轴，但它们仅对胚外结构做出贡献，例如卵黄囊和胎盘。我们的初步研究挑战了这一观点，并通过本提案的具体目标来检验假设。我们对小鼠的初步研究得出了三个关键发现。 (1) 小鼠肠道内胚层形成的新模型，结合了一种新的形态发生机制，导致胚胎和胚胎外细胞的广泛混合。 (2)原肠胚阶段胚胎信号中心周围的胚外（内脏）内胚层细胞的典型聚集。 (3) 胚胎外组织和胚胎组织的分离是哺乳动物发育的基本特征，但可能并不像人们认为的那么严格，而内脏内胚层（一种被定义为完全胚胎外的谱系）可能为胚胎本身提供细胞。该项目的主要目标是结合分子、胚胎学和实时成像技术来研究内脏内胚层（一种推测的胚胎外谱系）在哺乳动物肠道内胚层形态发生中所发挥的作用，该组织将产生呼吸道和消化道，以及相关器官，如肺、肝和胰腺。在目标 1 中，我们将定义介导胚胎中肠道内胚层形态发生的细胞行为。我们将使用现有的和新的报告菌株来可视化野生型胚胎和表现出内胚层缺陷的突变体中的细胞动态。在目标 2 中，我们将确定导致小鼠原肠胚信号中心周围胚胎外（内脏）内胚层细胞组织的事件顺序，并检验这种排列对于这些信号中心功能至关重要的假设。这将通过实时成像和对无法生成中线结构的突变体的分析来实现。在目标 3 中，我们将确定胎儿和成年小鼠的内脏内胚层和肠道内胚层组织之间是否存在谱系关系。我们将确定内脏内胚层是否是胚胎和成人肠道内胚层衍生组织的短暂或稳定组成部分，并将使用遗传诱导的命运图谱方法检验胚胎外（内脏）内胚层并非完全是胚胎外组织的假设。