Cytoplasmic Damage and Genotoxicity

描述（由申请人提供）：自伦琴发现X射线以来的世纪以来，放射学专业的学生一直被教导辐射诱导遗传损伤的典型靶点位于细胞核的DNA中。细胞质损伤的生物学后果在很大程度上是未知的。使用精确的带电粒子微束，申请人和他的合作研究者先前已经表明，靶向细胞质照射在涉及活性氧和氮物质的过程中诱导相同命中细胞的细胞核中的突变。最近的初步数据表明，这些损伤的后果可能导致非靶向/旁观者反应，并且命中细胞的后代显示基因组不稳定性增加。本次竞赛的总体目标是 更新的应用是i）表征由细胞质照射诱导的人小气道上皮模型中基因组不稳定性的诱导; 2）定义线粒体改变（融合/分裂）的作用和由细胞质照射诱导的随后的功能改变;和3）确定由细胞质照射诱导的导致生物反应的信号传导途径。提出了一系列三个相互关联的具体目标，以阐明三个可检验的假设;连接应用程序的三个主题：基因组不稳定性，线粒体损伤和炎症信号通路。最先进的带电粒子微束可以提供精确数量的α粒子，其束尺寸为~ 1微米，精度大于98%，这为解决放射生物学家几十年来一直感兴趣的问题提供了前所未有的机会：细胞核与细胞质损伤的差异生物效应。在过去的十年中，辐射生物学的一个主要范式转变是由于靶向细胞质照射的生物学后果的阐明和旁观者效应的发现。与基因组不稳定性和旁观者效应一起，该研究将解决一些关于细胞核靶点以及哺乳动物细胞中细胞质损伤如何处理的基本问题。这些研究对于了解细胞对DNA损伤的反应和低剂量辐射风险评估至关重要。

DESCRIPTION (provided by applicant): For over a century since the discovery of X-rays by Roentgen, students in radiological sciences have been taught that the quintessential target for radiation induced genetic damages resides in the DNA of the nucleus. The biological consequences of cytoplasmic damage are largely unknown. Using a precision charged particle microbeam, the applicant and his co-investigators have previously shown that targeted cytoplasmic irradiation induces mutations in the nucleus of the same hit cell in a process involving reactive oxygen and nitrogen species. Recent preliminary data suggest that the consequence of these damages can result in a non-targeted/ bystander response and that progeny of hit cells show an increase in genomic instability. The overall goals of this competitive renewal application are i) to characterize the induction of genomic instability in a human small airway epithelial model induced by cytoplasmic irradiation; 2) to define the role of mitochondrial alterations (fusion/ fission) and the subsequent functional alterations induced by cytoplasmic irradiation; and 3) to determine signaling pathways induced by cytoplasmic irradiation that result in the biological response. A series of three interrelated specific aims are proposed to elucidate three testable hypotheses; linking the three themes of the application: genomic instability, mitochondrial damage and inflammatory signaling pathways. A state of the art charge particle microbeam that can deliver a precise number of alpha particles with a beam size of ~ 1 micrometer and a precision greater than 98% provides an unprecedented opportunity to address an issue that has been of interest to radiobiologists for decades: the differential biological effects of nuclear versus cytoplasmic damage. A major paradigm shift in radiation biology in the last decade has resulted from the elucidation of the biological consequence of targeted cytoplasmic irradiation and discovery of the bystander effect. Together with the genomic instability and bystander effects, the study will address some of the fundamental issues regarding extranuclear target and how cytoplasmic damages are being processed in mammalian cells. Such studies are critically important understanding the cellular response to DNA damages and in low dose radiation risk assessment.