Regulation of Appendage Regeneration in Zebrafish

描述（由主要研究者提供）：成年硬骨鱼和有尾目两栖动物具有再生整个截肢附肢的能力。与此形成鲜明对比的是，哺乳动物四肢的再生愈合仅限于脚趾尖。在有尾目动物的肢体再生和硬骨鱼类动物的鳍再生过程中，再生受到精确的调节，只有适当的结构被替换。附件再生的一个经典和无法解释的问题是，受伤区域的成年细胞如何保留或识别完成这一过程所需的位置信息。维持这种“位置记忆”的核心问题是这些。首先，在再生过程中，细胞在多大程度上保持其谱系限制和分化状态？也就是说，一个谱系的分化的成体细胞是否能够贡献给一个或多个其他谱系，或者呈现出分化程度较低的形式？第二，哪些特定的分子程序对于保留和调节这些细胞内的位置信息是必不可少的？在这里，我们建议定义新的细胞和分子调控机制，保持位置信息，并指示再生更新的斑马鱼鳍，复杂的器官，含有骨，结缔组织间充质，表皮，血管，神经和色素细胞。在这个建议中，我们描述了一个程序化的方法来定位记忆，使用1）新技术的谱系追踪成年鳍细胞; 2）候选基因测试的基础上的新结果;和3）诱变筛选和位置克隆的正向遗传方法。用这种方法，我们将测试的假设，分化的成人附件组织表达区域特异性的调控因子，保持位置信息的再生保真度的重要配置文件。我们的分子遗传学方法将增加对再生器官发生过程中活跃的调控机制的理解，并为理解，甚至改变大多数人体器官再生能力的现有限制提供重要的视角。

DESCRIPTION (provided by Principal Investigator): Adult teleost fish and urodele amphibians have the capacity to regenerate entire amputated appendages. In striking contrast, regenerative healing of mammalian limbs is limited to the very tips of digits. During limb regeneration in urodeles and fin regeneration in teleosts, regeneration is precisely regulated such that only the appropriate structures are replaced. One of the classic and unexplained questions of appendage regeneration is how adult cells in the injured area retain or recognize the positional information necessary to accomplish this. The central questions by which this "positional memory" is maintained are these. First, to what extent do cells retain their lineage restriction and state of differentiation during regeneration? That is, are differentiated adult cells of one lineage able to contribute to one or more other lineages, or to assume a less differentiated form? Second, which specific molecular programs are essential for retaining and regulating positional information within these cells? Here, we propose to define new cellular and molecular regulatory mechanisms that maintain positional information and instruct regenerative renewal of zebrafish fins, complex organs containing bone, connective tissue mesenchyme, epidermis, blood vessels, nerves, and pigment cells. In this proposal, we describe a programmatic approach to positional memory, using 1) new technology for the lineage tracing of adult fin cells; 2) candidate gene testing based on new results; and 3) a forward genetic approach of mutagenesis screening and positional cloning. With this approach, we will test the hypothesis that differentiated adult appendage tissues express region-specific profiles of regulatory factors that maintain positional information important for regenerative fidelity. Our molecular genetic approach will increase understanding of regulatory mechanisms active during regenerative organogenesis, and provide important perspective for comprehending, and perhaps changing, the existing limitations in regenerative capacity of most human organs.