Local Role for Steroids in Regenerative Growth in Drosophila

项目总结 果蝇，果蝇，黑腹果蝇，是一个定义保守机制的成熟的模型系统 它控制着发育中的上皮细胞的增殖、存活、侵袭性和干细胞性。一批 临床上有意义的癌基因和肿瘤抑制基因已经在果蝇中被发现和定义(例如： Yki/YAP1、Notch和Aripelago/Fbw7)，以及多个果蝇肿瘤模型目前被用作 发现平台，以确定潜在的治疗化合物和鸡尾酒。泰曼果蝇(Tai) 和约克(Yki)转录共激活蛋白是唯一的果蝇同源基因 癌蛋白SRC-3和YAP1。TAI是蜕皮激素受体(ECR)的主要辅助激活剂，ECR是一种功能性的 核激素受体的同源物，控制上皮细胞和干细胞发育的许多方面。 Yki是河马途径的主要转录效应子。我们实验室发现了yki和tai 物理地结合在靶基因启动子上，并且这种太极拳复合体能够在 河马和类固醇激素途径在果蝇发育和病理性生长中的作用。 目前的项目集中在大yki轴在翅膀上皮细胞的动态平衡再生中的作用。 在受伤之后，因此处于哈罗德·德沃夏克所指出的伤口愈合和癌症的交叉点 他有先见之明地将癌症描述为“无法愈合的伤口”。我已经找到了初步证据表明 上皮创面周围细胞合成20-羟基蜕皮酮的能力局部降低 ECR的类固醇配体(20HE)可抑制伤口修复和再生。与此同时，我发现ECR 在伤口周围的细胞中，转录活性也被显著诱导。这些数据，鉴于 TAI-YKI复合体，可以将20HE/ECR类固醇信号与YKI/YAP1驱动的伤口部位的生长联系起来。 事实上，TAI支持在未受伤的椎间盘中表达某些YKI促生长靶点，这些靶点在 重新生成(例如dIlp8)。因此，我将测试类固醇激素20HE是 通过促进TAI依赖的yki靶标的转录活性来实现想象翼盘的再生。这个 本项目的具体目标是：1)测试翼盘再生对20HE生物合成的要求；2) 定义再生翼盘的ECR活动模式；3)测试本地对大yki轴的要求 再生性增长。在目标1中，我将比较耗尽20HE的翼盘的再生程度 生物合成基因控制盘，并确定20HE生物合成基因在 再生想象中的翼盘。在目标2中，我将把ECR激活与其他途径放在一起 在再生期间被激活。在目标3中，我将确定破坏太极拳协会对 翼盘再生程度和TAI依赖的yki靶标表达。这些研究的成功将 洞察局部激素合成如何调节动态平衡的伤口修复，并潜在地， 病理性癌症生长。

PROJECT SUMMARY The fruit fly, Drosophila melanogaster, is a well-established model system to define conserved mechanisms that control proliferation, survival, invasiveness, and stem-like qualities of developing epithelia. A number of clinically significant oncogenes and tumor suppressors have been discovered and defined in flies (e.g. Yki/Yap1, Notch and archipelago/Fbw7), and multiple Drosophila tumor models are currently being used as discovery platforms to identify potential therapeutic compounds and cocktails. The Drosophila Taiman (Tai) and Yorkie (Yki) transcriptional co-activator proteins are the sole fly orthologs of the well-established human oncoproteins SRC-3 and Yap1. Tai is the prime coactivator for the ecdysone receptor (EcR), a functional homolog of nuclear hormone receptors, that controls many aspects of epithelial and stem cell development. Yki is the main transcriptional effector of the Hippo pathway. Our laboratory discovered that Yki and Tai physically associate on target gene promoters and that this Tai-Yki complex enables crosstalk between the Hippo and steroid hormone pathways during developmental and pathologic growth in Drosophila. The current project is focused on a role for the Tai-Yki axis in homeostatic regrowth of wing epithelium following wounding, and thus lies at the intersection of wound healing and cancer noted by Harold Dvorak’s prescient description of cancer as “wounds that do not heal”. I have found preliminary evidence that transient and local reduction in the ability of cells surrounding epithelial wounds to synthesize 20-hydroxyecdysone (20HE), the steroid ligand of EcR, inhibits wound repair and regeneration. In parallel, I have found that EcR transcriptional activity is also significantly induced within cells surrounding the wound. These data, in light of the Tai-Yki complex, could link 20HE/EcR steroid signaling to Yki/Yap1-driven growth at the site of the wound. Indeed, Tai supports expression of certain Yki pro-growth targets in uninjured discs that are upregulated during regeneration (e.g. dIlp8). Thus, I will test the hypothesis that the steroid hormone 20HE is required for imaginal wing disc regeneration through promoting transcriptional activity of Tai-dependent Yki targets. The Specific Aims of this project are: 1) test the requirement for 20HE biosynthesis in wing disc regeneration; 2) define the pattern of EcR activity in regenerating wing discs; 3) test the local requirement for the Tai-Yki axis in regenerative growth. In Aim 1, I will compare the extent of regeneration of wing discs depleted of 20HE biosynthesis genes to control discs, and determine the pattern of 20HE biosynthesis gene expression in regenerating imaginal wing discs. In Aim 2, I will place EcR activation into the context with other pathways activated during regeneration. In Aim 3, I will determine the effect of disrupting Tai-Yki association on the extent of regeneration and Tai-dependent Yki target expression in wing discs. Success in these studies will provide insight into how local hormone synthesis regulates homeostatic wound repair and, potentially, pathologic cancer growth.