Molecular mechanisms of transcriptional repression through chromatin structure : Approaches from the actin-related protein Arp6

通过染色质结构抑制转录的分子机制：来自肌动蛋白相关蛋白 Arp6 的方法

基本信息

批准号：
13660076
负责人：
HARATA Masahiko
金额：
$ 2.3万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2001
资助国家：
日本
起止时间：
2001 至 2003
项目状态：
已结题

项目摘要

Actin plays central roles in the organization and dynamics of the cytosketeton. Within a few decades of the first isolation of actin from muscle, it was shown that actin filaments form the main architecture of the cytoskeleton, and that the dynamics of the cytoskeleton are regulated by the assembly/disassembly of the filament. Because of these characteristics of actin, previous researchers hypothesized that actin and/or its evolutionarily related molecules were involved in the organization and dynamics of the nucleus. However, actin filaments were observed only in the cytoplasm, and no molecule evolutionarily related to actin was identified at the time. The hypothesis was therefore regarded with skepticism for a long time. When the subcellular localizations of the other yeast Arps were investigated, unexpectedly more than half of them, including Arp5, Arp6, Arp7, Arp8, and Arp9, were predominantly localized in the nucleus, and Arp1, Arp2, Arp3, and Arp10 were observed in the cytoplasm. This suggests that the roles of Arps in the nucleus are not less significant than those in the cytoplasm. We have also discovered Arps localized in the nucleus in mammals. One of the nuclear Arps, Arp6 of budding yeast was shown to be a component of Swr1 complex, which exchange histone H2A for its variant H2A.Z. We showed that Arp6 was present in chromatin regions adjacent to telomere, and was required for proper organization of heterochromatin and distribution of Sir3. We also showed that human hArp6 interacted with hTPR1, which shuttles between cell nucleus and the cytoplasm. The property of hTPR1 might be involved in the regulation of Arp6 function. We have partially purified complexes containing hArp6, and analyzed it. Apart of these researches were performed in the laboratory of Prof.Ulrike Wintersberger.

肌动蛋白在细胞骨架的组织和动力学中起着核心作用。在首次从肌肉中分离肌动蛋白后的几十年内，人们发现肌动蛋白丝形成了细胞骨架的主要结构，并且细胞骨架的动力学受到丝的组装/分解的调节。由于肌动蛋白的这些特征，先前的研究人员假设肌动蛋白和/或其进化相关分子参与细胞核的组织和动力学。然而，肌动蛋白丝仅在细胞质中观察到，并且当时没有鉴定出与肌动蛋白进化相关的分子。因此，这一假说长期以来一直受到怀疑。当研究其他酵母 Arp 的亚细胞定位时，出乎意料的是，其中一半以上，包括 Arp5、Arp6、Arp7、Arp8 和 Arp9，主要定位于细胞核，而 Arp1、Arp2、Arp3 和 Arp10 在细胞质。这表明Arps在细胞核中的作用并不亚于在细胞质中的作用。我们还发现 Arps 位于哺乳动物的细胞核中。芽殖酵母的核 Arp 之一、Arp6 被证明是 Swr1 复合体的一个组成部分，该复合体将组蛋白 H2A 交换为其变体 H2A.Z。我们发现 Arp6 存在于端粒附近的染色质区域，并且是异染色质正确组织和 Sir3 分布所必需的。我们还表明，人类 hArp6 与 hTPR1 相互作用，hTPR1 在细胞核和细胞质之间穿梭。 hTPR1的特性可能参与Arp6功能的调节。我们部分纯化了含有 hArp6 的复合物，并对其进行了分析。其中部分研究是在 Ulrike Wintersberger 教授的实验室中进行的。