Damage signaling from irradiated to non-irradiated cells

广泛的长期目标：确定低剂量/通量电离辐射对人类二倍体细胞的影响，特别强调非靶向效应；即发生在不接受穿过细胞核的直接辐射的旁观者细胞的效应。该目标基于如下假设：“受电离辐射影响的细胞附近的非辐射细胞经历与受辐射细胞类似的生物效应，它们的反应是a)取决于细胞的氧化还原状态；b)连接蛋白43蛋白介导的缝隙连接细胞间通讯而不是通过其他机制；c)取决于照射和非照射细胞之间通讯的分子性质(S)；以及d)旁观者细胞的后代发生可测量的损伤，包括DNA损伤。为此，将在以下方面研究基因表达的变化、DNA损伤的诱导和氧化应激的持久性：1)在融合密度抑制培养中，与受电离辐射穿越的细胞相邻的旁观者细胞暴露在阿尔法粒子的通量中，通过这种通量，暴露的培养物中只有一小部分细胞经历粒子穿越细胞核。2)旁观者细胞与用短程β粒子发射体氚放射性标记的细胞混合，并种植足够数量的细胞以获得融合的单分子层。具体目的：i)表征氧化还原状态改变在旁观者未照射细胞中的生物效应表达中的作用。Ii)确定连接蛋白43通过其在间隙功能介导的细胞间通讯中的作用而不是通过其对短程扩散因子的影响来介导旁观者反应(S)。Iii)通过检测不同的连接蛋白在旁观者反应中的作用来表征受辐射和未受辐射的细胞之间沟通的分子的性质。确定应激效应在受影响的旁观者细胞及其后代中的持久性。重要性和与健康相关：低剂量/通量照射的细胞向未照射的旁观者细胞传递应激效应的中介机制的表征与辐射防护领域直接相关。这些研究的结果将有助于开发适当的模型来估计低剂量辐射暴露的风险，特别是在阿尔法粒子辐射诱发肺癌的情况下。它们还与诊断和治疗核医学有关，在核医学中，放射性核素正在被研究以检测各种疾病和治疗癌症。

Broad long-term objective: To define the effects of low-dose/fluence ionizing radiation in human diploid cells, with a particular emphasis on non-targeted effects; that is effects occurring in bystander cells which do not receive a direct radiation traversal through the nucleus. The objective is based on the hypothesis that "Non-irradiated cells in the vicinity of cells traversed by ionizing radiation experience similar biological effects as the irradiated cells, and their response is a) dependent on cellular redox-state; b) mediated by the effect of connexin43 protein on gap- junction intercellular communication and not through other mechanisms; c) dependent on the nature of the molecule(s) communicated between irradiated and non-irradiated cells; and d) measurable damage, including DNA damage, occurs in the progeny of the bystander cells. To this end, changes in gene expression, induction of DNA damage and persistence of oxidative stress will be studied in: 1) Bystander cells neighboring those cells traversed by ionizing radiation in confluent density-inhibited cultured exposed to fluences of alpha-particles by which only a small fraction of cells in the exposed culture experience a particle traversal through the nucleus. 2) Bystander cells mixed with cells radiolabeled with the short-range beta-particle emitter tritium and seeded in sufficient numbers to achieve confluent monolayers. Specific aims: I) Characterize the role of altered redox-state in mediating the expression of biological effects in bystander non-irradiated cells. II) Determine that connexin43 mediates the bystander response through its role in gap function mediated intercellular communication and not through its effect on short- range diffusible factor(s). III) Characterize the nature of the molecules communicated between irradiated and non-irradiated cells by examining the role of different connexins in the bystander response. IV) Determine the persistence of stressful effects in affected bystander cells and their progeny. Significance and health-relatedness: Characterization of the mechanism that mediate the transmission of stressful effects from low- dose/fluence irradiated cells to non-irradiated bystander cells are directly relevant to the field of radiation protection. The results of these studies will contribute to the development of adequate models to estimate risks of low dose-radiation exposure, especially in the case of alpha-particle radiation induced lung cancer. They are also relevant to diagnostic and therapeutic nuclear medicine where radionuclides are being investigated to detect various diseases and treat cancer.