Resolving heterogeneity in liver development

解决肝脏发育的异质性

• 批准号: 10005601
• 负责人: KIMBERLY D TREMBLAY
• 金额: $ 33.24万
• 依托单位: UNIVERSITY OF MASSACHUSETTS AMHERST
• 依托单位国家: 美国
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-09-20 至 2020-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10005601
• 关键词: ATAC-seq; Adult; Anterior; Bilateral; Cells; Cues; Data; Development; Developmental Process; Disease; Embryology; Endoderm; Epithelial; Fibroblast Growth Factor; Gene Expression; Genetic; Goals; Growth; Hepatic; Hepatic Tissue; Hepatocyte; Heterogeneity; Histologic; Homeostasis; In Vitro; Invaded; Knock-out; Laboratories; Lateral; Lip structure; Liver; Lobe; Mesenchyme; Mesoderm; Modeling; Molecular; Molecular Profiling; Mus; Natural regeneration; Organ; Organogenesis; Pattern; Play; Population; Process; Publishing; Reporter; Role; Route; Signal Transduction; Stem cells; Structure of septum transversum; Structure of sinus venosus of fetus; Testing; Tissues; Tube; cholangiocyte; experimental study; gastrulation; in vivo; insight; liver development; liver function; liver injury; novel; progenitor; response; transcriptome sequencing

Project Summary The definitive endoderm (DE) emerges during gastrulation as an epithelial sheet. This single cell sheet, which produces the entire gut tube and associated organs, is patterned and differentiates into organ domains in response to inductive cues provided by adjacent mesoderm-derived tissues. During induction, the hepatic progenitor, the hepatoblast, emerges from the DE as a group of thickened cells that express hepatic markers. The nascent hepatoblasts form a liver bud that will invade adjacent mesodermal tissue. Once invasion is complete, a single midline rostral lobe and two smaller bilaterally symmetric caudal lobes are evident. Although hepatoblasts and their associated mesoderm have each been regarded as uniform populations, we have discovered remarkable heterogeneity in both. Firstly, hepatoblast arise from two spatially distinct DE populations that each contributes uniquely to the liver bud. The ventral midline progenitors contribute mainly to the hepatoblasts that populate the anterior liver bud while the bilaterally symmetric lateral progenitors produce hepatoblasts that contribute to the posterior liver bud. Surprisingly, each progenitor has unique requirements for this process and is each associated with different supportive mesenchyme upon induction. For example, FGF signals are required to induce the sinus venosus bounded anterior hepatoblasts, while the septum transversum mesenchyme bounded posterior hepatoblasts require BMP signaling to be induced Furthermore, recent fate mapping from our group demonstrates that the anterior hepatoblasts mainly contribute to the caudal lobes while posterior hepatoblasts mainly contribute to the rostral lobe. Finally unpublished histological and molecular data suggests that the mesenchyme supporting the rostral and caudal lobes are distinct tissues. Together these observations suggest that normal development follows two routes for generating hepatoblasts. We hypothesize that the heterogeneity generated during early hepatic development is essential for normal liver function and that it aids in generating the heterogeneity recently identified in adult hepatocyte and cholangiocyte populations. Guided by the new developmental framework outlined above, the aims of our proposal use our expertise in embryology and the power of mouse genetics to further delineate this heterogeneity and to identify how it contributes to normal development. In Aim1 we propose to use conditional knock-out strategies to assess how FGF and BMP signals contribute to hepatoblast induction in vivo. In Aim2, we use an ex vivo approach and novel mouse reporters in vivo to uncover the developmental origin and adult contribution of the rostral and caudal lobe mesenchyme as well as determine the molecular signature of the rostral and caudal lobe hepatoblasts. The long-term goals are to understand how developmental heterogeneity contributes to key adult responses such as homeostasis and regeneration and to use these developmental insights to produce functional hepatic tissues in vitro.

项目摘要 确定的内胚层（DE）在胃层中以上皮片的形式出现。这个单细胞板，其中 产生整个肠管和相关的器官，被图案化，并区分为器官域 对相邻中胚层衍生组织提供的电感提示的反应。在归纳期间，肝 祖细胞，肝癌，作为一组表达肝脏标记的增稠细胞出现。 新生的肝细胞形成肝芽，将侵入相邻的中胚层组织。一旦入侵 完整，一个中线宽叶和两个较小的双侧对称尾瓣很明显。 尽管肝类母细胞及其相关的中胚层都被认为是统一的人群，但我们 两者都发现了显着的异质性。首先，肝激素来自两个空间上不同的de 每个人对肝芽的独特贡献。腹中线祖细胞主要贡献 双侧对称的侧祖细胞，到达前肝芽的肝细胞 产生有助于后肝芽的肝细胞。令人惊讶的是，每个祖先都有独特的 该过程的要求，诱导后各自与不同的支持性间质有关。 例如，需要FGF信号来诱导鼻窦静脉内骨的前肝细胞，而 隔膜间充质界有边界后肝类母细胞需要诱导BMP信号 此外，我们小组的近期命运映射表明，前肝细胞主要是 尾叶有助于尾叶，而后肝细胞主要促成the骨叶。最后 未发表的组织学和分子数据表明，间充质支持尾骨和尾骨 叶是不同的组织。这些观察结果共同表明，正常发展遵循两条路线 产生肝细胞。我们假设在早期肝发展过程中产生的异质性 对于正常的肝功能至关重要，它有助于产生最近确定的异质性 成人肝细胞和胆管细胞种群。在概述的新发展框架的指导下 以上，我们的提案的目的使用我们的胚胎学专业知识和老鼠遗传学的力量进一步 描述这种异质性，并确定它如何促进正常发展。在AIM1中，我们建议 使用有条件的淘汰策略来评估FGF和BMP信号如何促进肝细胞诱导 体内。在AIM2中，我们在体内使用了离体方法和新颖的鼠标记者来揭示发展 鼻瓣和尾叶间充质的起源和成人贡献，并确定分子 鼻瓣和尾叶肝细胞的签名。长期目标是了解如何 发育异质性有助于成人的关键反应，例如稳态和再生以及 使用这些发育见解在体外产生功能性的肝组织。