CYTOGENETICS--ALPHA PARTICLE INDUCED CHROMOSOMAL CHANGES

描述：（申请人描述）本项目的总体研究目标是了解辐射诱发病变的识别、处理和后果的机制基础，特别强调氡子代α粒子及其对人类健康的影响。核DNA变化显著影响人类健康，与细胞死亡、突变和致癌变化有明确的关系。然而，在非核目标中引起的应力对长期有害影响的潜在贡献尚不确定。很明显，细胞膜、细胞质和细胞核之间的分子相互作用有助于损伤识别、信号传导和反应途径。通过使用微束，可以有效地了解细胞成分在辐射响应中的作用。在这个项目中，我们将使用定义的影响（低至1）或100 keV/um α粒子照射细胞核、细胞质或群体中的已知细胞。未被击中的细胞（旁观者）可能受到活性氧的胁迫和/或受到诱导的移动细胞因子的影响。来自基因敲除小鼠、野生型、p53-和atm-的小鼠胚胎成纤维细胞将作为单种群和成对种群辐照。反应将分别在命中和未命中细胞中进行评估。我们会问：粒子间距会影响基于原子核的反应吗？细胞质辐照是否会引发生物反应？细胞特异性辐照是否在基因型依赖的基础上启动非击中细胞的反应？我们将研究微核的发病率；细胞凋亡，细胞生长发育；细胞周期延迟；通过蛋白表达和定位来表达基因，通过RT-PCR来表达mRNA。与该项目的其他项目一致，结合端点和精确的特定地点微束照射来解决明确的问题，将建立机制参数，并将定义低剂量下的α粒子响应性，重点是旁观者效应的贡献。

DESCRIPTION: (Applicant's Description) The overall research objectives of this program project are directed toward understanding the mechanistic bases for the recognition, processing and consequences of radiation induced lesions, with a particular emphasis on radon progeny alpha particles and their impact on human health. Nuclear DNA changes significantly impact human health with clear relationships to cell death, mutation and oncogenic changes. There is uncertainty however as to the potential contributions of stresses induced in non-nuclear targets to long term deleterious effects. It is clear that molecular interplay between membrane, cytoplasm and nucleus contributes to damage recognition, signaling and response pathways. An understanding of the role of cellular components in radiation responses can efficiently be obtained by use of a microbeam. In this project we will used defined influences (down to 1) or 100 keV/um alpha-particles to irradiate cell nucleus, cytoplasm or known cells in a population. Non-hit cells (bystanders) may be stressed by reactive oxygen species and/or affected by induced mobile cytokines. Mouse embryo fibroblasts derived from knockout mice, wild-type, p53-, and atm- will be irradiated both as single and as pair wise populations. Responses will be separately assessed in hit versus non-hit cells. We will ask the questions: Does particle spacing influence nucleus based responses? Does cytoplasmic irradiation initiate a biological response? Does cell specific irradiation initiate responses in non-hit cells on a genotype dependent basis? We will examine incidence of micronuclei; apoptosis, cell growth and development; cell cycle delay; and gene expression both by protein expression and localization, and mRNA by RT-PCR. In concert with the other projects of this program project, the combination of endpoints and precise site specific microbeam irradiation to address definitive question will establish mechanistic parameters and will define alpha-particle responsiveness at low doses with emphasis on the contribution of the bystander effect.