ROLE OF RAD9 IN BYSTANDER EFFECTS

对电离辐射暴露的总体细胞反应不限于直接照射的细胞， 包括邻近的“旁观者”。基本上每个终点都是常规用于检测细胞变化的 直接暴露于辐射，如突变、凋亡、微核形成或细胞周期检查点， 已经在旁观者身上研究过了这一现象引起了对生物学思维的范式转变， 辐射暴露的影响和相关健康风险;受影响的细胞群大于一次 相信。调节旁观者效应的机制还不清楚。然而，某些间隙连接 蛋白质，即，连接蛋白32和蛋白质如考克斯-2控制整个过程，而p21只是调节细胞的生长。 辐射诱导的G1到S检查点。我们已经证明，Rad 9调节旁观者的反应， 辐射，因为Rad 9 null增强旁观者凋亡和微核形成。Rad 9蛋白， 控制细胞周期检查点，DNA修复，凋亡和下游靶基因的反式激活， 直接照射的细胞，可能通过一种以上的途径影响旁观者反应。合作 与项目2和项目3的研究人员一起，我们发现Rad 9对于考克斯-2的旁观者诱导是必不可少的， p21（项目2），以及在HeLa细胞中产生连接蛋白32，其通常缺乏该蛋白， 增加旁观者辐射抗性和Rad 9以及TCTP的水平（项目3），这两者都起作用 在旁观者的过程中。我们还表明，TCTP和Rad 9物理相互作用（项目3）。我们的总体 Rad 9在辐射诱导的旁观者效应中起重要作用 涉及至少考克斯-2、p2 I、连接蛋白32和TCTP。解决这一假设的具体目标是：I。 确定Rad 9在细胞核与细胞质辐射诱导的旁观者效应中的活性; 2. 分析Rad 9功能结构域和蛋白质-蛋白质相互作用在旁观者过程中的作用; 3. 确立Rad 9依赖性旁观者诱导考克斯-2、p21等基因对旁观者的意义 监管; 4.确定Rad 9是否对旁观者诱变至关重要;以及5.定义的意义 Rad 9的调节和功能的连接通信。这些研究将揭示机制， Rad 9调节辐射诱导的旁观者效应，并将影响对生物学的理解。 放射治疗的影响，以及对改善放射治疗和更好地确定健康风险的影响。

The overall cellular response to ionizing radiation exposure is not limited to cells directly irradiated, but includes neighboring "bystanders". Essentially every endpoint used routinely to test for changes in cells direcfiy exposed to radiation, such as mutation, apoptosis, micronuclei formation or cell cycle checkpoints, has been studied in bystanders. This phenomenon has caused a paradigm shift in thinking about biological effects and associated health risks of radiafion exposure; the impacted cell population is larger than once believed. The mechanism regulating bystander effects is not well understood. However, certain gap junction proteins, i.e., Connexin 32, and proteins like Cox-2 control the overall process, whereas p21 just regulates the radiation-induced Gl to S checkpoint. We have shown that Rad9 regulates the bystander response to radiation, since Rad9 null enhances bystander apoptosis and micronuclei formation. Rad9 protein, which controls cell cycle checkpoints, DNA repair, apoptosis and transactivation of downstream target genes in directly irradiated cells, likely impacts on the bystander response via more than one pathway. In collaboration with investigators in Projects 2 and 3, we show that Rad9 is essential for bystander induction of Cox-2 and p21 (Project 2), and production of Connexin 32 in HeLa cells, which are normally devoid of the protein, increases bystander radiation resistance and levels of Rad9 as well as TCTP (Project 3), which both function in the bystander process. We also show that TCTP and Rad9 physically interact (Project 3). Our overarching hypothesis is that Rad9 plays an important role in radiation-induced bystander effects via mechanisms involving at least Cox-2, p2I, Connexin 32 and TCTP. Specific aims to address this hypothesis are: I. Determine the activity of Rad9 in nuclear versus cytoplasmic irradiation-induced bystander effects; 2. Analyze Rad9 functional domains and protein-protein interactions for roles in the bystander process; 3. Establish the significance of Rad9-dependent bystander induction of Cox-2, p21 and other genes for bystander regulation; 4. Determine if Rad9 is critical for bystander mutagenesis; and 5. Define the significance of junctional communication on the regulation and funcfion of Rad9. These studies will reveal mechanisms by which Rad9 regulates radiation-induced bystander effects, and will impact on understanding the biological response to radiation exposure, with implications for improving radiotherapy and better defining health risk.