Generation of Retinoid Signals During Development

发育过程中类维生素A信号的产生

• 批准号: 7926206
• 负责人: GREGG L DUESTER
• 金额: $ 25.21万
• 依托单位: SANFORD BURNHAM PREBYS MEDICAL DISCOVERY INSTITUTE
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-30 至 2011-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7926206
• 关键词: Address; All-Trans-Retinol; Alleles; Back; Binding; Biological Models; Cells; DNA; Defect; Development; Disease; Dose; Ectoderm; Embryo; Embryonic Development; Endoderm; Enzymes; Exhibits; Experimental Designs; FGF8 gene; Fibroblast Growth Factor; Fibroblast Growth Factor Receptors; Fishes; Forelimb; Gene Expression; Gene Targeting; Generations; Genes; Genetic Transcription; Goals; Growth; Heart; Hindlimb; Human; Knowledge; Laboratories; LacZ Genes; Lateral; Left; Length; Ligands; Limb Bud; Mediating; Mesoderm; Mus; Mutant Strains Mice; Neuroectoderm; Nuclear; Nuclear Orphan Receptor; Organ; Paraxial Mesoderm; Pathway interactions; Pattern; Phosphotransferases; Play; Primitive Streaks; Proteins; Rana; Reporter; Research Design; Response Elements; Retinaldehyde; Retinoic Acid Receptor; Retinoids; Role; Signal Pathway; Signal Transduction; Signaling Molecule; Site; Somites; Source; Spinal Cord; Staging; Stem Cell Development; Stem cells; Supplementation; Testing; Time; Tissues; Transgenes; Tretinoin; apoAI regulatory protein-1; base; cellular retinoic acid binding protein; embryonic stem cell; hindbrain; improved; intercellular communication; mutant; neural plate; prevent; receptor binding; receptor expression; retinaldehyde dehydrogenase; somitogenesis; spatiotemporal; tool

DESCRIPTION (provided by applicant): Retinoic acid (RA) is a cell-cell signaling molecule derived from retinol that controls several aspects of development. As RA is useful for differentiation of embryonic stem cells, studies designed to understand how RA performs its functions will be essential for development of stem cell-based treatments for disease. In order to generate replacement organs from stem cells we need to understand how embryos initially generate organs, including knowledge of the regulatory molecules that send signals between cells. RA signaling occurs when retinol is sequentially metabolized to retinaldehyde and then to RA which functions as a ligand for nuclear RA receptors that bind DNA and directly regulate gene expression. The regulatory enzyme controlling synthesis of RA during early embryogenesis has been discovered to be retinaldehyde dehydrogenase-2 (RALDH2) which oxidizes retinaldehyde to RA, initially only in posterior mesoderm. RALDH2 is conserved in human, mouse, chick, frog, and fish, and is the only enzyme synthesizing RA in early mouse embryos. Raldh2 null mutant mouse embryos lose all RA signaling activity normally present in the posterior portion of the embryo from the late primitive streak stage to the tailbud stage and do not develop beyond the early tailbud stage. These mutants exhibit disrupted somite segmentation and fail to generate forelimb buds, indicating that RA is required for proper development of these mesodermal tissues. Low-dose maternal dietary RA supplementation can rescue these defects. Our laboratory has discovered that a quite useful tool for unraveling RA function is to provide RA supplementation to Raldh2 mutants for various lengths of time and then follow where the exogenous RA stimulates transcription using an RA- reporter transgene also present in these embryos. Those studies have allowed us to hypothesize that Raldh2 functions only in a cell-nonautonomous fashion, meaning that RA synthesized in the mesoderm is secreted and acts on neighboring cells, but does not function within the cells producing RA. This important piece of information must now be integrated into our view of how RA controls mesodermal development during early development. In this proposal, Raldh2-/- mice carrying an RA-reporter transgene will be used as a model system for revealing the spatiotemporal mechanism of RA action during mesoderm development and the genes regulated. Raldh2-/- mice will be crossed with various other null mutant mice to address the mechanism of RA action. The specific aims are as follows: (1) we will determine the mechanism that directs RA action to the neuroectoderm and prevents RA activity in the presomitic mesoderm of RA-rescued Raldh2-l- embryos. (2) We will examine the mechanism of RA action required for proper somite formation and patterning including an analysis of the genes regulated by RA in the adjacent neuroectoderm and the signals sent from neuroectoderm to presomitic mesoderm. (3) The role RA signaling plays in forelimb budding will be investigated including the timing, target tissue, RA source tissue, and target genes.

描述（由申请人提供）：视黄酸是一种源自视黄醇的细胞 - 细胞信号分子，它控制着发育的几个方面。由于RA对于区分胚胎干细胞有用，因此旨在了解RA执行其功能的研究对于开发基于干细胞的疾病治疗至关重要。为了从干细胞产生替代器官，我们需要了解胚胎最初如何产生器官，包括了解细胞之间发送信号的调节分子的知识。当视黄醇顺序代谢为视网膜氢，然后将RA作为结合DNA并直接调节基因表达的核RA受体的配体起作用时，就会发生RA信号传导。已经发现，在早期胚胎发生过程中控制RA的合成的调节酶是视网膜脱氢酶-2（RALDH2），该脱氢酶-2（RALDH2）最初仅在中胚层后将视网膜醛氧化为RA。 RALDH2在人，小鼠，鸡，青蛙和鱼类中保守，并且是早期小鼠胚胎中唯一的酶合成RA。 RALDH2 NULL突变小鼠胚胎从晚期原始条纹阶段到尾梁阶段的胚胎后部中通常存在的所有RA信号传导活性通常存在，并且不会在早期的尾巴阶段发展。这些突变体表现出破坏的节点分割，无法产生前肢芽，表明RA是正确发展这些中胚层组织所必需的。低剂量的母体饮食补充可以挽救这些缺陷。我们的实验室发现，阐明RA功能的一种非常有用的工具是为RALDH2突变体提供RA补充，以进行各个时间长度，然后遵循这些胚胎中也存在的Ra-Reporter Transgene刺激转录的情况。这些研究使我们能够假设RALDH2仅以细胞nona术的方式起作用，这意味着中胚层中合成的RA被分泌并作用于邻近细胞，但在产生RA的细胞中不起作用。现在，必须将此重要的信息整合到我们对RA在早期发展过程中如何控制中胚层发展的看法。在此提案中，携带RA-Reporter转基因的RALDH2 - / - 小鼠将用作模型系统，用于揭示中胚层发育过程中RA作用的时空机制和受调节的基因。 RALDH2 - / - 小鼠将与其他各种无效突变小鼠交叉，以解决RA作用的机制。具体目的如下：（1）我们将确定将RA作用引导到神经外胚层的机制，并防止RA反应RaldH2-L-胚胎的前胚层中RA活性。 （2）我们将检查适当的体积形成和模式所需的RA作用机制，包括对相邻神经外胚层中RA调节的基因的分析以及从Neuroectoderm发送到前中胚层的信号。 （3）将研究RA信号在前肢发芽中的作用，包括时间，靶组织，RA源组织和靶基因。