INTERCELLULAR COMMUNICATION AND THE RADIATION-INDUCED BYSTANDER EFFECT

辐射引起的旁观者/非目标反应被认为会影响对暴露于电离辐射的健康风险的估计。已经提出了几种机制来调节诱导的旁观者效应。其中，缝隙连接通信被证明是一个关键的中介。 然而，影响辐射效应传播的交界点通信方面仍然存在 未定义。利用体内分析方法，本研究的目的是利用缝隙连接蛋白(连接蛋白)通透性的基本知识来研究不同的连接蛋白在辐射和邻近的旁观者肿瘤或正常细胞之间传播死亡诱导(生长延迟、凋亡)或促生存效应(增殖能力)中的作用。中心假设是体内的细胞微环境调节缝隙连接门控，从而在照射细胞和旁观者细胞之间传播生物学效应。这些事件受氧化代谢和DNA修复的调节，并导致受影响的旁观者细胞及其后代的短暂和持久的变化。在四个相互关联的特定目标中，我们建议在体内研究连接蛋白26、连接蛋白32和连接蛋白43通道的选择性特性对照射和旁观者细胞增殖能力的影响。 我们将确定环氧合酶-2(COX-2)信号对介导旁观者效应表达的缝隙连接通透性的影响。我们还将研究细胞间通讯，这可能导致旁观者细胞中DNA修复和检查点蛋白Rad9和翻译控制的肿瘤蛋白(TCTP)的调节。我们将采用新技术来识别辐射和旁观者细胞之间传递的信号代谢物，这些代谢物导致旁观者细胞中TCTP和Rad9的调节。与长期的健康风险相关，我们将在正常细胞中检查存活的旁观者细胞后代中信号通路的变化和基因组的不稳定性。拟议的实验建立在体外初步数据的基础上，这些数据将该计划的三个项目整合在一起。这些数据揭示了体内连接蛋白、TCTP、Rad9和COX-2之间的新的相互作用，并表明信号事件介导 通过细胞间通讯促进这些相互作用。

Radiation-induced bystander/non-targeted responses have been postulated to impact the estimation of health risks of exposure to ionizing radiation. Several mechanisms have been suggested to mediate the induced bystander effect. Among them, gap-junction communication has been shown to be a critical mediator. However, the aspects of junctional communication that affect propagation of radiation effects remain undefined. Using in vivo analytic approaches, the goal of this proposal is to exploit fundamental knowledge on permeability properties of gap junction proteins (connexins) to investigate the role of different connexins in propagating death-inducing (growth delay, apoptosis) or pro-survival effects (proliferative capacity) between irradiated and neighboring bystander tumor or normal cells. The central hypothesis is that the in vivo cellular microenvironment modulates gap-junction gating, and thereby propagation of biological effects between irradiated and bystander cells. These events are modulated by oxidative metabolism and DNA repair, and result in transient and persistent changes in affected bystander cells and their progeny. In four interrelated specific aims, we propose to investigate, in vivo, the effects of selective properties of connexin 26, connexin 32 and connexin 43 channels on the proliferative capacity of irradiated and bystander human cells. We will determine the effects of cyclooxygenase-2 (COX-2) signaling on the gap junction permeabilities that mediate the expression of bystander effects. We will also examine intercellular communication that may result in regulation of the DNA repair and checkpoint proteins, Rad9 and Translationally Controlled Tumor Protein (TCTP), in bystander cells. We will adapt novel technology to identify signaling metabolites transmitted between irradiated and bystander cells that lead to regulation of TCTP and Rad9 in bystander cells. With relevance to long term health risks, we will examine, in normal cells, altered signaling pathways and genomic instability in the progeny of surviving bystander cells. The proposed experiments build on in vitro preliminary data that integrate the 3 projects of this program together. These data unraveled novel in vivo interactions between connexins, TCTP, Rad9 and COX-2, and showed that signaling events mediated through intercellular communication promote these interactions.