Regeneration and transdetermination of imaginal discs of Drosophila

描述(申请人提供)：果蝇的成像盘能够再生，因此为我们提供了一个研究细胞多能性的模型系统。在特定条件下，每个想象盘“弱点”中的一小部分细胞会改变它们的命运。这种转换被称为转录决定(TD)，当WG过度表达或当光盘被切开时，这种转换发生的频率很高。对这些细胞的表达谱分析确定了在功能测试中显着修改TD的候选基因。其中一些候选基因是染色质重塑基因。此外，我们还鉴定了与小鼠肝再生增强因子(ALR)基因同源的类ALR基因、基质金属蛋白酶1(MMP1)，以及含有C-凝集素结构域的新基因DREG。虽然这三个基因的哺乳动物同源基因与特定组织的再生有关，但它们的作用机制尚不清楚。我们建议继续并完成功能测试，包括产生新的候选果蝇基因的突变。文在寅博士将测试斑马鱼的同源基因。在研究再生时，必须解决干细胞的问题。TD细胞会像干细胞一样分裂吗？将在TD细胞中诱导细胞克隆，以检测不对称分裂，这是干细胞行为的里程碑。这些分析将在有无TD特征化的增强子和抑制子的情况下进行，以测试这些基因是否通过改变细胞谱系模式、创始细胞的数量或细胞加倍时间来影响发育可塑性。这一建议将有助于理解哪些分子信号增加了再生潜力，以确保正常的组织维护和修复。简要概述果蝇每个成像盘中的少数特定细胞具有干细胞特性。如果受到伤害的挑战，它们会再生。我们将测试这些细胞是否不对称分裂，这是干细胞行为的一个里程碑。此外，我们将识别调节发育可塑性的基因，并测试它们的基因产物如何影响多能细胞及其周围环境。果蝇已经被用作研究人类疾病的模型系统，我们在这里看到了一个洞察干细胞生物学和再生的机会。

DESCRIPTION (provided by applicant): Drosophila imaginal discs are able to regenerate and thus provide us with a model system to study multipotency of cells. Under certain conditions a small set of cells in the "weak point" of each imaginal disc change their fate. This switch, known as transdetermination (TD), occurs with high frequency when wg is overexpressed or when a disc is cut through the "weak point". Expression profiling of these cells identified candidate genes which in functional tests significantly modified TD. Some of these candidates are chromatin-remodeling genes. Furthermore, we identified putative regeneration genes such as alr-like, a gene orthologous to the mouse gene augmenter of liver regeneration (alr), Matrix metalloproteinase 1 (Mmp1), and dReg, a novel gene that contains a C-lectin domain. Although the mammalian orthologs of these three genes have been linked to regeneration of specific tissues, the mechanism by which they act is not well understood. We propose to continue and complete the functional tests, including the generation of mutations in novel candidate Drosophila genes. Dr. Moon will test homologous zebrafish genes. In examining regeneration, the issue of stem cells must be addressed. Do TD cells divide like stem cells? Cell clones will be induced in TD cells to assay for asymmetrical divisions, a landmark of stem cell behavior. These analyses will then be performed in the presence and absence of characterized enhancers and suppressors of TD to test whether these genes affect developmental plasticity by modifying the cell lineage pattern, the number of founder cells or the cell-doubling times. This proposal will contribute to the understanding of which molecular signals increase regeneration potential to ensure normal tissue maintenance and repair. Short summary A few specific cells in each imaginal disc of Drosophila have stem cell properties. If challenged by injury they regenerate. We will test whether these cells divide asymmetrically, a landmark of stem-cell behavior. In addition, we will identify the genes that mediate developmental plasticity and test how their gene products affect multipotent cells and their surroundings. Drosophila has been used as a model system to study human disease and we see here an opportunity to gain insight into stem-cell biology and regeneration.