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.

项目摘要/摘要 中肠的特征是一系列同心，中等衍生的平滑肌层 和粘膜，周围是内胚层的上皮。在成熟的肠道中，这种上皮形成 指的类手指般的投影延伸到管腔中，称为Villi。在发育中的小鸡中，产生了肠绒毛 通过一系列上皮屈曲事件以逐步的方式。屈曲力通过 在相邻区分限制扩展时，上皮的狭窄生长 平滑肌。随着时间的流逝，上皮所经历的物理约束随着不同的层次而变化 平滑肌是依次建立的。这些平滑肌层的位置已建立 通过SHH和BMP梯度的活性，分别对此对此产生正面和负面影响 平滑肌差异。当它们形成时，每个肌肉层中纤维的方向取决于 肠道当时的机械环境进行分化。尽管有这个将军 中肠结构如何建立的概述，有关组织级的信息缺乏 建造其他肠段。前肢和后肠都来自相同的线性限度 肠管作为中心，并具有相同的一般同心组织。但是，有重要的 不同肠道段中平滑肌分化的厚度和时机的差异， 上皮衬里在三个部分中截然不同。在AIM 1中，负责独特的机制 将阐明前后肌中肌肉层的特征。已知的信号系统 负责在中肠检查中肠中平滑肌的位置和厚度 定性（通过原位杂交）以及定量（通过qpcr）到定性（通过原位杂交）至 确定它们与中肠的表达方式不同。这些信号将通过选举来操纵 体内以及通过在外植体培养中与激动剂和拮抗剂进行培养，并利用组织重组 在功能上测试其角色。 AIM 2中的实验将决定平滑的这些差异的程度 肌肉结构和动力学负责前后的独特上皮形态 胆量。药物将被用来阻断平滑肌分化以测试其必要性。形态计量学和 生物物理参数将测量并输入计算模型，以测试 可以在此基础上完全解释上皮形态。最后，在AIM 3中，我们将评估转录的方式 HOX和副群集的因子，已知可以在肠道内指定区域身份，改变了分子 以及区分前，中间和后肠的物理参数，从而将区域图案连接到 肠道形态发生。为此，涉及区域身份的转录FCTER将被束缚 将检查逆转录病毒载体以及生化和机械参数的变化。