Signals and mechanical forces controlling radial gut morphogenesis

控制径向肠道形态发生的信号和机械力

• 批准号: 10442794
• 负责人: CLIFFORD J. TABIN
• 金额: $ 35.02万
• 依托单位: HARVARD MEDICAL SCHOOL
• 依托单位国家: 美国
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2026-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10442794
• 关键词: Address; Agonist; Anatomy; Architecture; Biochemical; Biophysics; Characteristics; Chick; Chick Embryo; Computer Models; Congenital Abnormality; Defect; Development; Dimensions; Embryonic Development; Environment; Epithelial; Equilibrium; Erinaceidae; Esophagus; Event; Family; Fiber; Fingers; Gastrocoele; Gastrointestinal tract structure; Gene Expression Profiling; Generations; Genes; Genetic Transcription; Growth; Hindgut; In Situ Hybridization; Large Intestine; Lead; Light; Link; Location; Measures; Mechanics; Mesenchyme; Mesoderm; Microdissection; Midgut; Molecular; Molecular Genetics; Morphogenesis; Morphology; Mucous Membrane; Muscle; Muscle Fibers; Nutrient; Organ; Pathway interactions; Pattern; Pharmaceutical Preparations; Play; Primates; Primitive foregut structure; Property; Radial; Retroviral Vector; Role; Series; Shapes; Signal Induction; Signal Transduction; Small Intestines; Smooth Muscle; Specific qualifier value; Stress; Structure; Surface; System; Testing; Thick; Time; Tissue Recombination; Tissues; To specify; Tube; Undifferentiated; Variant; Villus; Work; antagonist; biophysical properties; experience; experimental study; gastrointestinal epithelium; in vivo; insight; intestinal villi; mathematical model; mechanical force; morphogens; programs; transcription factor; transcription factor USF

PROJECT SUMMARY/ABSTRACT The midgut is characterized by a series of concentric, mesodermally-derived layers of smooth muscle and mucosa, surrounding an inner, endodermally-derived epithelium. In the mature gut, this epithelium forms finger-like projections extending into the lumen, called villi. In the developing chick, intestinal villi are generated in a step-wise manner, through a series of epithelial buckling events. Buckling forces are generated through the confined growth of the epithelium at a time when expansion is restricted by the adjacent differentiating smooth muscle. The physical constraint experienced by the epithelium changes over time as different layers of smooth muscle are established sequentially. The location of these smooth muscle layers is established through the activity of gradients of Shh and Bmp, which, respectively, have positive and negative effects on smooth muscle differentiation. As they form, the orientation of the fibers in each muscle layer depends upon the mechanical environment of the gut at the time the layer undergoes differentiation. In spite of this general outline of how the midgut architecture is established, there is a dearth of information regarding the tissue-level construction of the other gut segments. Both the foregut and the hindgut arise from the same linear primative gut tube as the midgut, and have the same general concentric organization. However, there are significant differences in the thickness and timing of smooth muscle differentiation in the different gut segments, and the epithelial lining differs dramatically in the three segments. In Aim 1, the mechanisms responsible for the distinct characteristics of the muscle layers in the fore- and hindgut will be elucidated. The signaling systems known to be responsible for defining the location and thickness of the smooth muscle in the midgut will be examined in the fore- and hindgut segments qualitatively (by in situ hybridization) as well as quantitatively (by qPCR) to determine how they differ in expression from the midgut. These signals will be manipulated by electoration in vivo and through culturing with agonists and antagonists in explant culture and utilizing tissue recombination to test their roles functionally. Experiments in Aim 2 will determine the extent to which these differences in smooth muscle architecture and dynamics are responsible for the distinct epithelial morphology of the fore-and hind guts. Drugs will be employed to block smooth muscle differentiation to test their necessity. Morphometric and biophysical parameters will be measured and entered into computational models to test the degree to which epithelial morphology can be entirely explained on this basis. Finally, in Aim 3 we will assess how transcription factors of the Hox and paraHox clusters, known to specify regional identity within the gut, alter the molecular and physical parameters that differentiate the fore-, mid- and hindgut, thereby connecting regional patterning to morphogenesis of the gut. To that end, transcription fctors involved in regional identity will be misexpressed ustilizing retroviral vectors, and changes in biochemical and mechanical parameters will be examined.

项目概要/摘要 中肠的特征是一系列同心、中胚层衍生的平滑肌层 和粘膜，围绕内胚层衍生的上皮。在成熟的肠道中，这种上皮形成 伸入管腔的手指状突起，称为绒毛。在发育中的雏鸡中，产生肠绒毛 以逐步的方式，通过一系列上皮屈曲事件。屈曲力是通过产生的 当扩张受到邻近分化的限制时，上皮的有限生长 平滑肌。上皮所经历的物理约束随着时间的推移而变化，因为不同的层 平滑肌依次建立。这些平滑肌层的位置已确定 通过Shh和Bmp梯度的活动，它们分别对 平滑肌分化。当它们形成时，每个肌肉层中纤维的方向取决于 该层进行分化时肠道的机械环境。尽管有这样的一般 关于中肠结构如何建立的概述，缺乏有关组织水平的信息 其他肠道片段的构建。前肠和后肠都源自同一个线性原语 肠管如同中肠，一般具有相同的同心组织。然而，有显着 不同肠段平滑肌分化的厚度和时间存在差异， 这三个部分的上皮衬里差异很大。在目标 1 中，负责不同的机制 将阐明前肠和后肠肌肉层的特征。已知的信号系统 负责定义中肠平滑肌的位置和厚度将在以下中进行检查 定性（通过原位杂交）和定量（通过 qPCR）对前肠和后肠片段进行分析 确定它们与中肠的表达有何不同。这些信号将受到选举的操纵 体内并通过在外植体培养物中与激动剂和拮抗剂一起培养并利用组织重组来 测试他们的角色功能。目标 2 中的实验将确定这些平滑差异的程度 肌肉结构和动力学决定了前后肢不同的上皮形态 胆量。将使用药物来阻止平滑肌分化以测试其必要性。形态测量和 将测量生物物理参数并将其输入计算模型以测试其程度 在此基础上可以完全解释上皮形态。最后，在目标 3 中，我们将评估转录如何 Hox 和 paraHox 簇的因子已知可指定肠道内的区域特征，从而改变分子 以及区分前肠、中肠和后肠的物理参数，从而将区域模式与 肠道的形态发生。为此，涉及区域身份的转录因子将被错误表达 利用逆转录病毒载体，并检查生化和机械参数的变化。