Regionalization of the Vertebrate Endoderm

脊椎动物内胚层的区域化

• 批准号: 6875030
• 负责人: VICTORIA E. PRINCE
• 金额: $ 28.33万
• 依托单位: UNIVERSITY OF CHICAGO
• 依托单位国家: 美国
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-07-05 至 2007-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6875030
• 关键词: Xenopus oocyte; biological signal transduction; cell differentiation; cell transplantation; chick embryo; complementary DNA; digestive system; ectoderm; endocrine gland /system; endoderm; fibroblast growth factor; fluorescence microscopy; gene expression; histogenesis; in situ hybridization; nuclear receptors; nutrition related tag; pancreas; polymerase chain reaction; retinoate; retinoid binding proteins; transcription factor; vertebrate embryology; zebrafish

DESCRIPTION (provided by applicant): Our long-term objective is to use the advantages of the zebrafish model system to investigate how the vertebrate endoderm is regionalized such that endocrine and digestive organs, including the pancreas, are specified and develop in the correct location. The results of our studies may ultimately facilitate experiments to direct human stem cells to differentiate into specific pancreatic cell types in vitro. Such approaches offer promise for transplantation therapies for diabetes and pancreatic cancers. Our general strategy is to test the hypothesis that molecular mechanisms known to be important in regionalization of the neural ectoderm are also important for endoderm regionalization. In support of this hypothesis, we have established that the secreted signaling molecule retinoic acid (RA), which plays an important role in regionalization of both neural ectoderm and mesoderm, is critical to endoderm regionalization. Thus, RA is required for specification of the pancreas, and exogenous RA has the remarkable capacity to cause anterior endoderm to form large numbers of ectopic pancreatic cells. We propose specific aims to: (1) Determine whether RA is required for pancreas specification in tetrapod vertebrates; (2) Investigate the molecular and cellular mechanism of RA signal transduction during zebrafish pancreas specification; (3) Test the hypothesis that Hox and Parahox genes regionalize the endoderm; and (4) Investigate the roles of Wnt and FGF signaling molecules in regionalization of the endoderm. RA signals may be received in the endoderm where they act cell-autonomously to specify pancreas, or alternatively may be received in adjacent tissues, which then send secondary signals to the endoderm. We will use a cell transplantation approach to distinguish between these hypotheses. Hox genes, and related Parahox genes, encode evolutionarily conserved transcription factors. The vertebrate Hox genes regionalize ectoderm and mesoderm and are frequently RA targets. We are in the unique position of having cDNAs to all the zebrafish Hox genes, this will allow us to use gain and loss-of-function approaches (Mrna mis-expression and morpholino knockdown) to determine whether Hox genes also act to regionalize the endoderm. Finally, we will use a combination of knockdown, dominant-negative, and mis-expression approaches to investigate whether other secreted signaling molecules implicated in posteriorizing the neural ectoderm, FGFs and Wnts, are also involved in endoderm regionalization.

描述(申请人提供)：我们的长期目标是利用斑马鱼模型系统的优势来研究脊椎动物内胚层是如何区域化的，以便内分泌和消化器官，包括胰腺，被指定并在正确的位置发育。我们的研究结果可能最终有助于指导人类干细胞在体外分化为特定类型的胰腺细胞的实验。这些方法为糖尿病和胰腺癌的移植治疗提供了希望。我们的总体策略是检验这一假设，即已知在神经外胚层区域化中重要的分子机制对内胚层区域化也很重要。为了支持这一假说，我们已经证实，分泌的信号分子视黄酸(RA)在神经外胚层和中胚层的区域化中起着重要的作用，是内胚层区域化的关键。因此，胰腺的规范需要RA，而外源性RA具有显著的诱导前内胚层形成大量异位胰腺细胞的能力。我们提出的具体目标是：(1)确定四足类脊椎动物胰腺规范是否需要RA；(2)研究斑马鱼胰腺规范过程中RA信号转导的分子和细胞机制；(3)检验HOX和ParaHox基因对内胚层区域化的假设；以及(4)研究Wnt和FGF信号分子在内胚层区域化中的作用。RA信号可以在内胚层中接收，在那里它们以细胞自主的方式作用于胰腺，或者也可以在邻近组织中接收，然后将次级信号发送到内胚层。我们将使用细胞移植的方法来区分这些假说。HOX基因和相关的ParaHox基因编码进化上保守的转录因子。脊椎动物HOX基因将外胚层和中胚层区域化，经常成为RA的靶标。我们处于拥有所有斑马鱼HOX基因的独特位置，这将使我们能够使用获得和功能丧失的方法(mRNA错误表达和吗啉基因敲除)来确定HOX基因是否也起到将内胚层区域化的作用。最后，我们将使用基因敲除、显性负性和错误表达相结合的方法来研究与神经外胚层的后部化有关的其他分泌信号分子，FGFs和WNTs是否也参与内胚层的区域化。