14-3-3 IMPLICATIONS IN TOPOISOMERASE II PHARMACOLOGY

描述：DNA拓扑异构酶II(Topo II)是一种普遍存在的核酶 它催化不同三级结构的相互转化 DNA这种酶对细胞增殖是绝对必要的，因为它 在有丝分裂前破坏物理上互锁的DNA。Topo II也是一种 一类广泛使用的化疗药物的临床相关靶点 毒品。TOPO II生物化学的研究揭示了以下几个机制 哪些肿瘤细胞对细胞毒作用有反应或逃避 TOPO-II导向的抗癌药物。在过去三年，校长 研究人员一直在发展一种假说，即Topo II活性可能是 由蛋白质-蛋白质相互作用和这些蛋白质的调节所介导 也可能影响肿瘤细胞对Topo II毒物的反应。其他人则有 描述了酵母和果蝇中的Topo II相互作用蛋白(TIPS) 是忠实的染色体分离所必需的。一个人类的同源物 酵母尖端，SGS1，很可能是引起基因改变的 布鲁姆综合征。因此，Topo II蛋白相互作用的研究具有 揭示了这种酶在人类肿瘤中的未被认可的作用。 首席调查员的研究建议将重点放在 Topo-II介导的细胞毒作用中Topo-II蛋白的相互作用 毒品。为此，建立了人HeLa细胞基因表达文库。 筛选与主要α蛋白的C末端相互作用的蛋白质 人类Topo II的形式。其中一个尖端已被确定为epsilon 人类14-3-3蛋白的亚型。14-3-3蛋白质，一种异常高的 在植物、真菌和哺乳动物中发现的保守蛋白质家族 反复与许多原癌和致癌细胞有牵连 信号通路。14-3-3蛋白似乎也隔离了细胞的凋亡 死亡激动剂Bad，在IL-3对T细胞的保护中。《校长》 因此，调查人员提出1)测试14-3-3/TOPO II 相互作用是真实的，发生在完整的细胞中，2)研究 这一相互作用的生化和药理学后果 肿瘤细胞过度表达14-3-3蛋白。高水平的保护 14-3-3蛋白，它们在细胞生长信号中的意义 细胞凋亡，提示14-3-3/Topo II相互作用可能是 具有重要的生物学意义。最重要的是，这些互动还可能 调节肿瘤细胞对Topo-II导向的抗肿瘤药物的敏感性。

DESCRIPTION: DNA topoisomerase II (topo II) is a ubiquitous nuclear enzyme which catalyzes the interconversion of the various tertiary structures of DNA. This enzyme is absolutely essential to cellular proliferation since it decatenates physically interlocked DNA prior to mitosis. Topo II is also a clinically relevant target for a widely useful class of chemotherapeutic drugs. The study of topo II biochemistry has revealed several mechanisms by which tumor cells respond to, or evade, the cytotoxic effects of the topo-II-directed anticancer drugs. In the past three years, the Principal Investigator has been developing the hypothesis that topo II activity can be mediated by protein-protein interactions and modulation of these proteins may also affect tumor cell response to topo II poisons. Others have described topo II interactive proteins (TIPs) from yeast and Drosophila that are necessary for faithful chromosomal segregation. A human homolog of the yeast TIP, Sgs1, is likely to be the causative gene that is altered in Bloom's syndrome. Therefore, study of topo II protein interactions has revealed unappreciated roles for the enzyme in human neoplasia. The Principal Investigator's studies propose to focus instead on the role of topo II protein interactions in the cytotoxic action of topo-II-directed drugs. Toward this aim, a human HeLa cell cDNA expression library has been screened for proteins that interact with the C-terminus of the major alpha form of human topo II. One of the TIPs has been identified as the epsilon isoform of human 14-3-3 protein. 14-3-3 proteins, an unusually highly conserved protein family found in plants, fungi, and mammals, have been implicated repeatedly in numerous protooncogenic and oncogenic cellular signaling pathways. 14-3-3 proteins also appear to sequester the apoptotic death agonist, Bad, in IL-3 protection of T cells. The Principal Investigator therefore proposes 1) to test whether the 14-3-3/topo II interaction is authentic and occurs in intact cells and 2) to investigate the biochemical and pharmacological consequences of this interaction in tumor cells overexpressing 14-3-3 protein. The high level of conservation of 14-3-3 proteins, their implication in cellular growth signaling and now apoptosis, suggest that 14-3-3/topo II interactions are likely to be biologically significant. Most importantly, these interactions may also modulate tumor cell susceptibility to topo-II-directed antitumor drugs.