Regeneration and transdetermination of imaginal discs of Drosophila

描述（由申请人提供）：果蝇想象盘具有再生能力，为我们研究细胞多能性提供了一个模型系统。在某些条件下，每个想象磁盘的“弱点”中的一小部分细胞改变了它们的命运。当wg过度表达或当一个圆盘通过“弱点”被切断时，这种开关就会高频率地发生，称为转定（TD）。这些细胞的表达谱鉴定出候选基因，这些基因在功能测试中显著改变了TD。其中一些候选基因是染色质重塑基因。此外，我们鉴定了假定的再生基因，如alr-like，一个与小鼠肝再生基因增强器（alr）同源的基因，基质金属蛋白酶1 (Mmp1)，和dReg，一个包含c -凝集素结构域的新基因。尽管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，包括在新的候选果蝇基因中产生突变。文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，以测定不对称分裂，这是干细胞行为的一个里程碑。这些分析将在TD特征增强子和抑制子存在和缺失的情况下进行，以测试这些基因是否通过改变细胞谱系模式、创始细胞数量或细胞倍增次数来影响发育可塑性。这一建议将有助于理解哪些分子信号增加再生潜力，以确保正常组织的维持和修复。在果蝇的每个象盘中，有一些特定的细胞具有干细胞的特性。如果受到伤害，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，我们将确定介导发育可塑性的基因，并测试其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，我们在这里看到了深入了解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.