Probing Complexity of UV Induced Apoptosis in Drosophila

描述（由申请人提供）：探索紫外线诱导果蝇细胞凋亡的复杂性：细胞凋亡是一个进化保守的过程，涉及多种疾病，包括癌症和神经退行性疾病。细胞凋亡的调控是由一个复杂的基因（蛋白质）网络控制的。我们的初步数据表明，紫外线诱导的果蝇胚胎凋亡可以通过不同的细胞死亡调控基因介导。更有趣的是，受照射细胞的细胞环境（分化状态）决定了哪个细胞死亡调控基因在紫外线照射下被激活以诱导细胞死亡，即当处于分化阶段的胚胎受到紫外线照射时，死神基因被一种DNA损伤依赖机制诱导，该机制涉及果蝇同系物共济失调毛细血管扩张突变，mei-41（很可能也包括dP53）。然而，当胚胎处于分化阶段之前时，hac-1 （Apaf-1和Ced-4的同系物）基因被诱导而不是reaper基因。在这个发育阶段，诱导hac-1表达是紫外线诱导的细胞凋亡所必需的。但与紫外线诱导死神不同，紫外线诱导hac-1似乎不受核DNA损伤的影响，也不受mei-41突变的影响（mei-41 [D5]）。长期以来人们一直注意到紫外线诱导的细胞死亡可通过DNA损伤依赖性和非依赖性机制介导。然而，目前尚不清楚紫外线诱导细胞凋亡的机制是如何发挥和协调的。上述结果表明，果蝇胚胎为系统分析紫外线诱导细胞死亡的复杂性提供了一个很好的模型。本研究的重点是研究紫外线诱导早期胚胎hac- 1表达和凋亡的分子机制。此外，我们将应用基因组学方法来全面了解紫外线诱导的基因组反应和细胞凋亡。本提案的目的是深入阐明不同的细胞死亡调控途径如何被部署来介导基因毒性刺激诱导的细胞死亡。这些调查提供的信息将有助于我们对细胞死亡调控和皮肤癌发生的全面了解。通过该项目揭示的分子机制应该为确定替代治疗靶点提供见解，特别是对于那些对dna损伤剂有抵抗力的癌症。

DESCRIPTION (provided by applicant): Probing the complexity of UV induced apoptosis in Drosophila: Apoptosis is an evolutionarily conserved process that has been implicated in a variety of diseases, including cancer and neurodegenerative diseases. Regulation of apoptosis is under the control of a complex network of genes (proteins). Our preliminary data showed that UV induced apoptosis in Drosophila embryo can be mediated by different cell death regulatory genes. More interestingly, the cellular context (differentiation status) of the irradiated cell determines which cell death regulatory gene is activated to induce cell death upon UV irradiation, i.e. When embryos in differentiating stage were irradiated with UV, the reaper gene is induced by a DNA damage -dependent mechanism that involves Drosophila homologue of Ataxia Telangiectasia Mutated, mei-41 (and very likely dP53 as well). However, when embryos prior to differentiating stage were irradiated, the hac-1 (Homologue of Apaf-1 and Ced-4) gene is induced instead of reaper. The induction of hac-1 expression is required for UV induced apoptosis at this developmental stage. But in contrast to UV induction of reaper, UV induction of hac-1 appears to be independent of nuclear DNA damage and was not affected by mei-41 mutation (mei-41 [D5]). It has long been noticed that UV induced cell death can be mediated by DNA damage -dependent and -independent mechanisms. However, it remains unclear as to how are the mechanisms deployed and coordinated to mediate UV induced apoptosis. The aforementioned findings indicate that Drosophila embryo provides an excellent model for systematic analysis of the complexity of UV -induced cell death. The focus of this proposal is to characterize the molecular mechanism underlying UV induced hac- 1 expression and apoptosis in early stage embryos. In addition, we will apply genomic approaches to gain comprehensive understanding of UV -induced genomic response and apoptosis. The goal of this proposal is to elucidate in depth how different cell death regulatory pathways may be deployed to mediate genotoxic stimuli -induced cell death. The information provided by these investigations will contribute to our comprehensive understanding of cell death regulation and skin carcinogenesis. Molecular mechanisms uncovered through this project should provide insights for identifying alternative therapeutic targets, especially for cancers that are resistant to DNA-damage agents.