Identifying novel strategies to promote tissue regeneration

描述（由申请人提供）：再生是指用功能等同的组织替代丢失组织的能力。关于再生的生物学需要解决两个基本问题：（1）再生性生长与正常发育期间发生的生长有何不同？(2)为什么有些组织可以再生，而另一些不能？果蝇的成虫盘是成虫结构（如翅膀和眼睛）的幼虫原基，在受损后能够再生。直到最近，大多数关于椎间盘再生的研究都涉及在成年雌性果蝇的果蝇中培养破碎的椎间盘。因此，很难对再生生长的调节因子进行基因筛选。我们的实验室已经开发出一种研究成虫盘再生的方法，这种方法不需要费力的外科技术。促凋亡基因在发育中的翅袋中短时间的表达消融了大部分的翅袋组织，并留下了存活细胞的边缘。再生生长恢复消融袋和成年苍蝇可以有相对正常大小的翅膀。再生过程中的早期事件是形态原Wingless的上调，其导致Myc蛋白水平的增加;增加Myc水平增强再生。此外，再生发生有效地在光盘从早期的第三龄幼虫，但在后期的第三龄阶段的损害不会导致再生。因此，在许多其他生物体中，Wnt蛋白在再生过程中上调，并且成虫盘再生的能力取决于发育阶段。为了理解组织损伤如何启动再生过程，将表征在组织损伤时被激活的无翅基因的增强子的特性（目的1），并定义激活增强子的信号通路。防止激活相同的增强子在老年幼虫的组织损伤响应的机制也将被表征。目的2旨在确定和表征遗传改变，促进再生在老年人的成虫盘。目标3将解决椎间盘生长扰动与发育时机之间的相互关系。

DESCRIPTION (provided by applicant): Regeneration refers to the ability to replace tissue that has been lost with tissue that is functionally equivalent. Two fundamental questions need to be addressed with respect to the biology of regeneration: (1) how does regenerative growth differ from the growth that occurs during normal development? (2) Why can some tissues regenerate while others cannot? Drosophila imaginal discs, the larval primordial of adult structures such as the wing and the eye, are capable of regenerating after damage. Until recently, most studies of imaginal-disc regeneration involved culturing fragmented discs in the abdomens of adult female Drosophila. It was therefore difficult to conduct genetic screens for regulators of regenerative growth. Our laboratory has developed a way of studying regeneration in imaginal discs that does not require laborious surgical techniques. Expression of a pro-apoptotic gene for a short period in the developing wing pouch ablates most of the pouch tissue and leaves a rim of surviving cells. Regenerative growth restores the ablated pouch and adult flies can have wings of relatively normal size. An early event during regeneration is upregulation of the morphogen Wingless which results in increased levels of Myc protein; increasing Myc levels enhances regeneration. Additionally, regeneration occurs efficiently in discs from early third instar larvae but damage at the later third instar stage does not result in regeneration. Thus, as in many other organisms, a Wnt protein is upregulated during regeneration and the ability of imaginal discs to regenerate depends on the developmental stage. To understand how tissue damage initiates the process of regeneration, the properties of an enhancer of the wingless gene that is activated upon tissue damage will be characterized (Aim 1) and the signaling pathways that activate the enhancer will be defined. The mechanisms that prevent activation of the same enhancer in response to tissue damage in older larvae will also be characterized. Aim 2 seeks to identify and characterize genetic alterations that promote regeneration in older imaginal discs. Aim 3 will address the interrelationship between perturbations in imaginal disc growth and developmental timing.