Identifying novel strategies to promote tissue regeneration

描述（由申请人提供）：再生是指用功能等效的组织替换已经丢失的组织的能力。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有些组织不能？果蝇的想象盘是幼虫的原始结构，如翅膀和眼睛，在损伤后能够再生。直到最近，大多数关于想象椎间盘再生的研究都涉及在成年雌性果蝇腹部培养碎片状椎间盘。因此，很难对再生生长的调节因子进行遗传筛选。我们的实验室已经开发出一种不需要费力的手术技术来研究影像学椎间盘再生的方法。促凋亡基因在发育中的翼袋中的短时间表达会使大部分囊组织消融，只留下一小部分存活细胞。再生生长恢复了消融的眼袋，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，导致Myc蛋白水平升高；增加Myc水平可以增强再生能力。此外，三龄幼虫早期的椎间盘再生效率很高，但三龄后期的损伤不会导致再生。因此，正如在许多其他生物中一样，Wnt蛋白在再生过程中被上调，镜像盘的再生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，将对组织损伤时激活的无翼基因的增强子的特性进行表征（目的1），并定义激活增强子的信号通路。该机制，防止激活相同的增强剂，以应对组织损伤的老年幼虫也将被表征。目的2旨在识别和表征促进旧影像学椎间盘再生的遗传改变。目的3将解决在想象磁盘生长和发育时间的扰动之间的相互关系。

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.