Regulation of UV-induced apoptosis

描述（由申请人提供）：为了确保多细胞生物体中的组织稳态，必须修复或消除因环境损伤（如紫外线照射）而受损的细胞。细胞修复和细胞死亡之间的决定的失调在视网膜的退行性疾病中起重要作用，例如年龄相关性黄斑变性，以及更普遍地在癌症中。了解细胞损伤防御和细胞死亡的调节将提高我们预防和/或治疗此类疾病的能力。 目前的模型表明，细胞存活信号和促凋亡刺激之间的平衡控制着细胞修复和死亡之间的决定。这些竞争信号如何整合和解释，以实现对细胞命运的准确控制，在体内是不完全理解的。需要使用遗传可访问模型系统的研究，以进一步了解这一调控系统。 申请人已经进行了初步研究，以分析视网膜中细胞生死决定的调节。这些研究表明，叉头盒O转录因子Foxo以及AP-1转录因子DFos是必需的Jun-N-末端激酶信号通路下游的细胞凋亡反应的UV诱导的DNA损伤在发展中的果蝇视网膜。重要的是，这些研究表明，紫外线诱导的细胞凋亡是由受体酪氨酸激酶途径发出的生存信号，这是已知的抑制Foxo。这些数据表明，通过Foxo整合压力和生存信号驱动体内细胞死亡和受损细胞修复之间的决定。该模型将通过实验解决以下具体目标来测试：（i）分析视网膜中UV诱导的转录反应的调节。使用表达谱分析方法，将在视网膜中分析促凋亡和促存活基因表达程序的调节。(ii)测试JNK信号的双相激活是否控制细胞对UV的反应。申请人提出，响应于UV应激的JNK激活发生在两个阶段：促进细胞恢复的初始阶段，以及当DNA损伤持续时，诱导促凋亡基因表达的第二阶段。基因实验将被用来测试这个模型。(iii)使用遗传方法识别视网膜紫外线反应的调节因子。果蝇系统的一个优点是能够使用遗传筛选来快速识别信号通路的新组件。在这里，这种方法将被用来确定新的基因，将允许解决有关控制细胞命运和信号特异性的具体问题。 这里提出的实验，预计将显着推进我们的理解，在完整的组织中的细胞的生命/死亡的决定的调节，因此，将与未来的合理的治疗方法退行性疾病。

DESCRIPTION (provided by applicant): To ensure tissue homeostasis in multicellular organisms, cells damaged by environmental insults (such as UV irradiation) have to be either repaired or eliminated. Misregulation of the decision between cell repair and cell death plays an important role in degenerative diseases of the retina, such as age-related macular degeneration, as well as more generally in cancer. Insight into the regulation of cellular damage defense and cell death will increase our ability to prevent and/or treat such diseases. Current models suggest that the balance between cell survival signals and pro-apoptotic stimuli controls the decision between repair and death of a cell. How these competing signals are integrated and interpreted to achieve accurate control over cell fate in vivo is incompletely understood. Studies using genetically accessible model systems are required to gain further insight into this regulatory system. The applicant has performed preliminary studies to analyze the regulation of cellular life-death decisions in the retina. These studies show that the Forkhead Box O transcription factor Foxo as well as the AP-1 transcription factor DFos are required downstream of the Jun-N-terminal Kinase signaling pathway for the apoptotic response to UV-induced DNA damage in the developing Drosophila retina. Importantly, these studies show that UV-induced apoptosis is repressed by survival signals emanating from Receptor Tyrosine Kinase pathways, which are known to inactivate Foxo. These data suggest that integrating stress and survival signals through Foxo drives the decision between cell death and repair of damaged cells in vivo. This model will be tested by addressing the following specific aims experimentally: (i) Analyze the regulation of UV-induced transcriptional responses in the retina. Using expression profiling approaches, the regulation of pro-apoptotic and pro-survival gene expression programs will be analyzed in the retina. (ii) Test whether biphasic activation of JNK signaling governs the cellular response to UV. The applicant proposes that JNK activation in response to UV stress occurs in two phases: an initial phase that promotes cell recovery and, when DNA damage persists, a second phase that induces pro-apoptotic gene expression. Genetic experimentation will be used to test this model. (iii) Identify regulators of the retinal UV response using genetic approaches. One advantage of the Drosophila system is the ability to use genetic screens to rapidly identify new components of signaling pathways. Here, such approaches will be used to identify new genes that will allow addressing specific questions regarding the control of cell fate and signaling specificity. The experiments proposed here are expected to significantly advance our understanding of the regulation of cellular life/death decisions in intact tissues and will therefore be of relevance to future rational therapeutic approaches for degenerative diseases.