Mechanochemical mechanisms of intestinal villus development and regeneration

项目总结 肠绒毛由被上皮层包裹的间充质核心组成，这两层共同增加了 肠道吸收表面积近100倍。放射、化疗药物引起的绒毛损伤 许多胃肠道疾病会导致绒毛萎缩，导致营养吸收不良和消化不良。 并发症。值得注意的是，在许多情况下，萎缩的绒毛完全再生以恢复其手指状的形态， 然而，在其他情况下，再生过程受到损害，导致持续性绒毛萎缩。如何绒毛 再生它们的形态以及为什么这个过程会失败是未知的。此外，我们对此缺乏了解 哺乳动物绒毛最初是如何在发育过程中建造的。该项目的长期目标是了解如何 在发育和再生过程中，整合信号和力量来塑造哺乳动物绒毛，从而改善 人类肠道组织的生长和再生策略。 绒毛的形成始于胚胎，周围的间充质细胞聚集在一起。 形成凝结的上皮，称为绒毛团。而绒毛似乎是绒毛所必需的 形态发生，其形成的机制尚未确定。在这里，我探索了一个链接 在这些在哺乳动物胚胎发育过程中首先形成绒毛的事件和那些重建的事件之间 在成年后的再生过程中。首先，我量化绒毛团的物理属性，并测试 间充质凝聚成簇，并随后将上皮弯曲成绒毛。 通过间充质细胞的收缩，并通过不同的界面张力增强。接下来，我将检查 这些间充质凝聚事件和绒毛形成的机制背后的遗传机制。 具体地说，我提出并测试了一个由单细胞RNA测序数据生成的模型，其中收缩 内皮下间充质细胞的活性是由内皮素依赖的钙信号触发的，而 收缩通过缝隙连接在相邻细胞之间局部耦合，以驱动簇的形成 和上皮细胞的弯曲。最后，我测试上皮下间充质细胞是否利用类似的机械力化学。 再生绒毛结构的机制，以响应成人肠道的损伤，此外， 用单细胞分辨率表征绒毛再生以确定新的成年绒毛遗传介体 建筑。总之，这些研究将定义信号和力量如何相互作用来形成和改造哺乳动物 肠道绒毛，确定新的治疗靶点以刺激绒毛再生，更广泛地说，将解决 组织形状和大小如何再生的问题。

PROJECT SUMMARY Intestinal villi comprise a mesenchymal core ensheathed by an epithelial layer that together increase the intestinal absorptive surface area nearly 100 fold. Damage to villi incurred by irradiation, chemotherapeutics, and many gastrointestinal maladies cause villus atrophy, resulting in nutrient malabsorption and digestive complications. Remarkably, in many cases atrophied villi fully regenerate to restore their finger-like morphology, yet in other situations the regenerative process is impaired, resulting in persistent villus atrophy. How villi regenerate their morphology and why this process can fail are unknown. Moreover, we lack an understanding of how mammalian villi are initially built during development. The long-term goal of this project is to understand how signals and forces are integrated to sculpt mammalian villi during development and regeneration so as to improve strategies for growing and regenerating human intestinal tissue. Villus formation initiates in the embryo with the aggregation of mesenchymal cells adjacent to the overlying epithelium that form condensations, termed villus clusters. While villus clusters seem to be required for villus morphogenesis, the mechanisms underlying their formation have not been identified. Here, I explore a link between these events that first build villi in the mammalian embryo during development and those that rebuild them in the adult during regeneration. First, I quantify the physical properties of villus clusters and test whether mesenchymal condensation into clusters, and the subsequent buckling of the epithelium into villi, is initiated through mesenchymal cellular contractility and reinforced by differential interfacial tension. Next, I examine the genetic mechanisms underlying the mechanics of these mesenchymal condensation events and villus formation. Specifically, I put forth and test a model generated from single-cell RNA sequencing data wherein the contractile activities of the subepithelial mesenchyme are triggered by Endothelin-dependent Ca2+ signaling, and the contractions become coupled locally between neighboring cells through gap junctions to drive cluster formation and epithelial buckling. Finally, I test whether subepithelial mesenchymal cells utilize similar mechanochemical mechanisms to regenerate villus architecture in response to damage in the adult intestine, and additionally, characterize villus regeneration at single cell resolution to identify new genetic mediators of adult villus architecture. Together, these studies will define how signals and forces interact to form and reform mammalian intestinal villi, identify new therapeutic targets to stimulate villus regeneration, and, more broadly, will address the question of how tissue shape and size are regenerated.