Damage signaling from irradiated to non-irradiated cells

广泛的长期目标：确定低剂量/注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;即发生在未接受穿过细胞核的直接辐射的旁观者细胞中的效应。目的是基于以下假设：“在电离辐射穿过的细胞附近的未辐照细胞经历与辐照细胞相似的生物学效应，并且它们的反应a）依赖于细胞氧化还原状态; B）由连接蛋白43蛋白对间隙连接细胞间通讯的作用介导，而不是通过其他机制; c）依赖于在辐照和未辐照细胞之间传递的分子的性质;和d）在旁观者细胞的后代中发生可测量的损伤，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续性：1）在接触到α粒子的通量的融合密度抑制培养物中，邻近被电离辐射穿过的那些细胞的旁观者细胞，通过所述α粒子的通量，暴露培养物中只有一小部分细胞经历粒子穿过细胞核。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，并接种足够数量以获得融合单层。具体目标：I）表征改变的氧化还原状态在介导旁观者非辐照细胞中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作用来介导旁观者应答。III）通过检查不同连接蛋白在旁观者应答中的作用来表征在辐照的和未辐照的细胞之间通信的分子的性质。IV）确定受影响的旁观者细胞及其后代中应激效应的持续性。重要性和健康相关性：介导应激效应从低剂量/注量辐照细胞传递到未辐照旁观者细胞的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，以估计低剂量辐射照射的风险，特别是在α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，在这些医学中，正在研究放射性核素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.