Altered Nuclear Protein Interactions and Radiosensitizat

热疗是已知的最有效的放射增敏剂之一。因此，项目1的目标是阐明短期中温热辐射增敏的机制以及通过增加热剂量增加放射增敏的机制(S)，从而确定热诱导放射增敏增强剂的细胞靶点。众所周知，高温增强了蛋白质与核成分的结合，导致整个细胞核内蛋白质-蛋白质相互作用的改变。越来越多的证据表明，其中一些变化会导致放射增敏。然而，导致放射增敏的核蛋白相互作用的确切变化仍不清楚。因此，这项拟议工作的目标是描绘短期、中度高温引起的导致辐射敏感性增加的核蛋白关联的变化。第一步是确定热诱导的DNA修复蛋白MREL 1从细胞核到细胞质的移位和/或其功能伙伴的解离是否通过短时间、中等温度(特定目标1)导致放射增敏。其次，我们将确定核蛋白结合的哪些变化有助于通过增加热剂量来增加放射增敏。假设的第二部分是，当热剂量超过放射增敏所需的最低剂量(例如，急性热疗)时，蛋白质与DNA-核基质附着区结合的热诱导增加有助于提高放射敏感性。如果蛋白质构象的改变导致蛋白质结合的改变，从而导致热诱导的放射增敏，那么从这些效应中恢复可能需要蛋白质与分子伴侣(S)之间的联系，例如热休克蛋白70，这将在特定的目标3中进行测试。在特定的目标4中，将通过确定适度的热疗和HIR的增强剂是否至少产生一些急性热敏的放射增敏效应来检验辐射增敏效应的增加的假设。

Hyperthermia is one of the most effective radiosensitizers known. Therefore, the goal of Project 1 is to delineate the mechanisms of radiosensitization by short-duration moderate hyperthermia and the mechanism(s) by which radiosensitization is increased via increasing thermal dose, so that the cellular targets for enhancers of heat-induced radiosensitization will be defined. It is known that hyperthermia enhances protein binding to nuclear components, leading to altered protein-protein interactions throughout the nucleus. Accumulating evidence suggests that some of these changes cause radiosensitization. However, the exact changes in nuclear protein interactions that contribute to radiosensitization remain unknown. Thus, the objectives of the proposed work are to delineate the changes in nuclear protein associations induced by short duration, moderate hyperthermia that lead to increased radiosensitivity. The first step will be to determine if the heat-induced translocation of the DNA-repair protein, Mrel 1, from the nucleus to the cytoplasm and/or its dissociation from its functional partners causes radiosensitization by short-duration, moderate hyperthermia (Specific Aim 1). Second, we will determine which changes in nuclear protein association contribute to increasing radiosensitization by increasing thermal dose. The second part of the hypothesis is that the heat-induced increase in the binding of proteins to DNA-nuclear matrix attachment regions contribute to increased radiosensitivity at thermal doses above the minimum required for radiosensitization (e.g., acute hyperthermia). If altered protein conformations are responsible for changes in protein associations that lead to heat-induced radiosensitization, it is likely that recovery from these effects would require an association between the protein and a molecular chaperone(s) e.g., hsp70, which will be tested in Specific Aim 3. The hypothesis that an increasing spectrum of radiosensitizing effects contribute to enhanced radiosensitization will be tested in Specific Aim 4, by determining if moderate hyperthermia, plus an enhancer of HIR produces at least some of the radiosensitizing effects of acute hyperthermia.