APOPTOSIS

电离辐射(IR)可直接或间接地通过产生反应性氧化物种(ROS)来诱导多种细胞类型的细胞凋亡。许多证据表明，IR诱导的细胞凋亡是DNA损伤的结果，但也有证据表明，非核能量沉积(例如，在质膜中)可以启动细胞凋亡。目前尚不清楚非核启动的细胞凋亡是否涉及脱氧核糖核酸依赖的过程，特定的凋亡触发物种的性质，以及非核IR触发的凋亡途径(S)是什么。因此，这个项目的总体目标是增加对IR在非核和核部位启动细胞凋亡机制的理解。将使用在选定的亚细胞区域中产生RO的两种独特方法的组合。电离辐射微束将用于选择性地照射核和非核细胞区域。此外，还将使用光敏剂，选择性地产生OH、OR和OOR，作为“模拟”IR的一种手段。该项目有三个具体目标：(1)测量细胞凋亡的诱导：在非核和核IR后使用微束，并将其效果与产生OH、OR和OOR的光活性物质诱导的细胞凋亡进行比较。我们将验证这样的假设，即IR在非核区产生的ROS可以触发细胞凋亡，但效率低于IR/ROS在细胞核中的效率。(2)确定由空间受限的IR/ROS在核与非核细胞区触发的不同凋亡通路在IR中对整体细胞凋亡的相对贡献。(3)验证靶细胞中的非核IR/ROS可以导致邻近未处理(旁观者)细胞的凋亡的假设。在这些研究中获得的机制洞察力应该会增加对复杂但临床上重要的问题的理解，即细胞凋亡对放射治疗的肿瘤治愈或癌症发展的贡献，并有助于提出操纵细胞凋亡途径以获得治疗收益的方法。

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.