APOPTOSIS

电离辐射（IR）可通过直接或间接机制产生活性氧化物质（ROS）介导导致许多细胞类型的凋亡。许多证据表明IR诱导的细胞凋亡是由DNA损伤引起的，但也有证据表明非核能沉积（例如，在质膜中）可以启动细胞凋亡。目前还不清楚非核启动的细胞凋亡是否涉及DNA依赖的过程，具体的细胞凋亡触发物种的性质是什么，以及什么样的凋亡途径（S）是由非核IR触发的。因此，本项目的总体目标是增加对非核和核部位的IR启动细胞凋亡的机制的理解。将使用两种独特方法的组合，用于在选定的亚细胞区域中产生ROS。电离辐射微束将被用于选择性地照射细胞核和非核区域。该项目有三个具体目标：（1）测量细胞凋亡的诱导：使用微束进行非核和核IR后，并将其功效与产生OH，OR和OOR的光活性剂诱导的细胞凋亡进行比较。我们将检验IR在非核区域产生的ROS可以触发细胞凋亡的假设，但效率低于IR/ROS在核中。(2)（3）验证靶细胞中的非核IR/ROS可引起邻近未处理细胞（旁观者）凋亡的假设。在这些研究中获得的机制的见解应该增加理解复杂的，但临床上重要的问题，细胞凋亡的贡献肿瘤治愈放射治疗或癌症的发展，并帮助建议手段操纵细胞凋亡途径的治疗收益。

Ionizing radiation (IR) can cause apoptosis in many cell types, mediated by generation of reactive oxidizing species (ROS) either directly by the IR or via indirect mechanisms. Much evidence indicates that IR-induced apoptosis results from damage to DNA, but there is also evidence suggesting that non-nuclear energy deposition (e.g., in plasma membrane) can initiate apoptosis. It is unclear whether non-nuclear initiated apoptosis involves DNA-dependent processes, what the nature of the specific apoptosis triggering species is, and what apoptotic pathway(s) are triggered by non-nuclear IR. Hence, the overall goal of this project is to increase understanding of mechanisms of apoptosis initiation by IR in non-nuclear and nuclear sites. A combination of two unique approaches for generating ROS in selected subcellular regions will be used. Ionizing radiation microbeams will be used to irradiate selectively nuclear and non-nuclear cell regions. This will be complemented by use of photoactive agents that selectively produce OH, OR and OOR as a means to "mimic" IR. The project has three specific aims: (1) Measure the induction of apoptosi: after non-nuclear and nuclear IR using microbeams and compare that efficacy with apoptosis induced by photoactive agents that produce OH, OR and OOR. We will test the hypothesis that ROS produced by IR in non-nuclear regions can trigger apoptosis, but with lower efficiency than IR/ROS in the nucleus. (2) Determine the relative contributions of different apoptotic pathways triggered by spatially restricted IR/ROS in nuclear versus non-nuclear cell regions to overall apoptosis from IR. (3) Test the hypothesis that nonnuclear IR/ROS in target cells can cause apoptosis in neighboring, untreated (bystander) cells. The mechanistic insight gained in these studies should increase understanding of complex, but clinically important, questions about the contribution of apoptosis to tumor cure from radiation therapy or to cancer development, and help suggest means to manipulate apoptotic pathways for therapeutic gain.