Mechanisms regulating hepatic specification and differentiation in zebrafish

描述(由申请人提供)： 有人认为，肝脏和腹侧胰腺起源于共同的祖细胞，并具有几个共同的发育特征。在小鼠胚胎组织外植体系统中，当肝诱导过程被成纤维细胞生长因子(FGFs)和骨形态发生蛋白(BMPS)等信号阻断时，培养的内胚层启动了一个基因Pdx1，该基因通常在前肠内胚层[SIC]中表达，包括胃、十二指肠和胰腺，但不在肝脏中表达。这些表达Pdx1的内胚层外植体进一步孵育后，出现了胰腺内分泌细胞和外分泌细胞，这表明腹侧内胚层具有形成包括肝脏和胰腺在内的多种组织的潜力。这项研究计划的总体目标是以斑马鱼为主要模式生物，阐明调节肝脏规格及其可塑性的机制，以及随后的分化。首先，我将通过对Wnt2bb和Bmp2b信号以及Hedgehog和Bmp2b信号进行更详细的谱系追踪分析和[原文如此]功能丧失和功能获得的上位性分析，来研究Bmp2b如何调节肝脏和胰腺的命运决定。其次，我将研究Forkhead box和Homeobox转录因子如何在Bmp2b信号下游发挥作用，调节肝脏和胰腺的命运决定。将进行表达分析以及特定于内胚层的功能丧失和功能获得实验。第三，我将对大规模诱变筛选中的4个突变体进行详细的表征。它们在内胚层器官的生长和分化方面表现出特定的缺陷。一旦确定优先顺序，识别潜在的分子损伤之后将进行广泛的分析，例如表达模式分析和功能丧失和功能获得的研究。我希望通过一系列的这些实验，我可以回答肝脏和胰腺是如何从共同的祖先发展到获得其独特和重叠的功能的根本问题。 公共卫生相关性：肝病是美国和世界范围内的主要死亡原因。一般来说，它反映了对损伤的慢性反应，修复和再生导致瘢痕形成和/或肿瘤形成。通常情况下，成年胚胎的修复和再生是胚胎发育的总称。因此，了解其发生机制对慢性损伤和肝癌的预防和治疗具有直接意义。

DESCRIPTION (provided by applicant): It has been suggested that the liver and the ventral pancreas originate from common progenitors and share several developmental features. When the liver induction process was prevented in a mouse embryonic tissue explant system by blockig [sic] signals such as Fibroblast growth factors (Fgfs) and Bone morphogenetic proteins (Bmps), the cultured endoderm turned on a gene, Pdx1, that normally expressed in the foregut endoderm [sic], including the stomach, duodenum and pancreas, but not in the liver. Further incubation of these Pdx1 expressing endodermal explants led to the appearance of pancreatic endocrine and exocrine cells, suggesting that the ventral endoderm has the potential to give rise to multiple tissues, including the liver and pancreas. The overall goal of this research proposal is to elucidate mechanisms regulating liver specification and its plasticity, and subsequent differentiation using zebrafish as the main model organism. First, I will investigate how Bmp2b regulates liver versus pancreatic fate decision by performing more detailed lineage tracing analysis ad [sic] loss- and gain-of-function epistatic analysis of Wnt2bb and Bmp2b signaling as well as Hedgehog and Bmp2b signaling. Second, I will investigate how Forkhead box and Homeobox transcription factors function downstream of Bmp2b signaling to regulate liver versus pancreatic fate decision. Expression analysis as well as endoderm-specific loss-and gain-of-function experiments will be performed. Third, I will perform detailed characterization of 4 mutants from large scale mutagenesis screening. They show specific defects in the growth and differentiation of endodermal organs. Once prioritized, identification of the underlying molecular lesion will be followed by extensive analysis, such as expression pattern analysis and loss-and gain-of-function studies. I expect I can answer the fundamental question how the liver and pancreas develop from common progenitors to acquire their unique and overlapping function with series of these experiments. PUBLIC HEALTH RELEVANCE: Liver disease is a major cause of death in the United States and world wide. In general it reflects a chronic response to injury, in which repair and regeneration lead to scarring and/or neoplasia. Often, repair and regeneration in the adult recapitulate embryonic development. Thus, understanding the mechanisms of development has direct implications for prevention and treatment of chronic injury and liver cancer.