The Examination of the Infectious Chromatin Hypothesis and the Development of an Experimental System for the DM-transfer Mediated by the Extracellular Micronuclei

感染性染色质假说的检验和细胞外微核介导的 DM 转移实验系统的开发

基本信息

批准号：
09680696
负责人：
SHIMIZU Noriaki
金额：
$ 2.11万
依托单位：
HIROSHIMA UNIVERSITY
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1997
资助国家：
日本
起止时间：
1997 至 1998
项目状态：
已结题

项目摘要

Double minutes (DMs) harboring the amplified oncogenes are found in a broad spectrum of human tumour cells. We previously found that the elimination of DMs led to the reversion of tumour cell phenotypes and the cellular differentiation. The previous studies suggested the selective incorporation of DMs into micronuclei mediates the elimination of DMs. However it remains to be uncovered how the content of micronuclei was eliminated. This study revealed that the micronuclei were extruded to the extracellular fluids, and just the mechanism explained the elimination of DMs quantitatively. The extracellular micronuclei were enriched with DMs, had apparently normal cytoplasmic membrane and nuclear membrane, and had undegraded DNA.Furthermore, we developed a quite physiological method for the purification of extracellular micronuclei. Based on these nature of the extracellular micronuclei, it seemed conceivable that the DMs might be transferred intercellularly through the medium of extracellul … More ar micronuclei. We examined this possibility thoroughly and carefully, however, by all means, we never succeeded the intercellular DM-transfer mediated by the extracellular micronuclei. On the other hand, it was also important to clarify the reason why the transfer was not possible. Therefore, we focused our attention to the intracellular motion that relates to the extracellular elimination of DMs, and obtained much achievement. Namely we uncovered the intranuclear unique motion of DMs which was coupled to the DNA replication. Acentric DMs are segregated to the daughter cells by the attachment to the mitotic chromosomes. We found that the detachment from the chromosome by the treatment of some drugs or the malfunctioning of p53 protein let DMs remain at the cytoplasm. In most cases, the cytoplasmic DMs attached to the nuclear membrane from the outside, were surrounded by the nuclear lamin proteins which the process led to the micronucleation at the S-phase. Consequently, the DMs in the micronuclei should be damaged which explained why the micronuclei-mediated DM-transfer was not successful. Less

在众多的人类肿瘤细胞中发现了带有扩增的癌基因的双分钟（DMS）。我们先前发现，消除DMS导致肿瘤细胞表型和细胞分化的逆转。先前的研究表明，将DMS选择性掺入微核中介导了DMS的消除。然而，尚待发现如何消除微核的含量。这项研究表明，将微核被挤出到细胞外液中，并且只是定量解释了DMS的消除。细胞外的微核富含DMS，显然具有正常的细胞质膜和核膜，并且未依赖DNA。我们开发了一种相当物理的方法来纯化细胞外微核中的物理方法。基于细胞外微核的这些性质，似乎可以想象DM可以通过细胞外的介质间插入……更多的AR微核。我们对这种可能性进行了彻底和仔细的检查，但是，通过手段，我们从未成功过由细胞外微核介导的细胞间DM转移。另一方面，澄清不可能转移的原因也很重要。因此，我们将注意力集中在与DMS细胞外效率有关的细胞内运动上，并获得了很多成就。也就是说，我们发现了与DNA复制耦合的DMS的本质独特运动。通过附着在有丝分裂染色体上的分离，分离的DMS分离为子细胞。我们发现，通过治疗某些药物或p53蛋白的故障使DMS保留在细胞质处，从染色体脱离。在大多数情况下，从外部附着在核膜上的细胞质DM被核层粘蛋白蛋白包围，该过程导致了S期的微核。因此，微核中的DMS应损坏，这解释了为什么微核介导的DM转移不成功的原因。较少的