Identifying novel strategies to promote tissue regeneration

描述(申请人提供)：再生是指用功能相同的组织替换丢失的组织的能力。关于再生生物学需要解决两个基本问题：(1)再生生长与正常发育过程中的生长有何不同？(2)为什么有些组织可以再生，而另一些组织不能再生？果蝇的想象盘是成体结构的幼虫原基，如翅膀和眼睛，在受损后能够再生。直到最近，大多数关于想象盘再生的研究都涉及在成年雌性果蝇的腹部培养碎片化的盘。因此，很难对再生生长的调节者进行基因筛查。我们的实验室已经开发出一种不需要费力的外科技术来研究想象中的椎间盘再生的方法。在发育中的翼囊中短期表达促凋亡基因会消融大部分的翼囊组织，并留下一圈存活的细胞。再生生长恢复了被烧毁的眼袋，成年苍蝇可以拥有相对正常大小的翅膀。再生过程中的一个早期事件是形态生成物Wingless上调，导致Myc蛋白水平增加；增加Myc水平可促进再生。此外，早期三龄幼虫的圆盘再生效率很高，但三龄后期幼虫的损伤不会导致再生。因此，就像在许多其他生物中一样，Wnt蛋白在再生过程中上调，而想象中的盘再生的能力取决于发育阶段。为了了解组织损伤如何启动再生过程，将描述在组织损伤时激活的无翼基因增强子的特性(目标1)，并定义激活增强子的信号通路。此外，还将描述防止同一增强子在组织损伤时被激活的机制。目标2试图识别和描述促进较老的成像盘再生的基因改变。目标3将解决影像盘生长中的扰动和发育计时之间的相互关系。

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.