Membrane-Transport Signaling Involving the GTPase Cycle of G proteins

涉及 G 蛋白 GTP 酶循环的膜运输信号转导

基本信息

批准号：
18207008
负责人：
KATADA Toshiaki
金额：
$ 31.87万
依托单位：
The University of Tokyo
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (A)
财政年份：
2006
资助国家：
日本
起止时间：
2006 至 2007
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-18207008/
关键词：
Signal transduction Protein Gene Genome project G protein GTPase cycle

项目摘要

G proteins, which cycle between the two different conformations of GTP- and GDP-bound states, play important roles as a "molecular switch" in many intracellular signaling pathways. The G protein families include 1) translation factors involved in protein synthesis and mRNA degradation, 2) trimeric G proteins, and 3) small GTPases. The small GTPases, such as Ras, Rab, Arf, and Rho/Rac family, are involved in the regulation of cell growth and differentiation, intracellular vesicle trafficking, and cell shape and adhesion. However, there are still many other small GTPases, of which functions are unknown. In this study, we have identified and characterized novel small GTPases exhibiting unique biochemical properties or tissue expression.1. The Arl8 GTPase was essential for lysosome biogenesis in the macrophage-like coelomocytes of C. elegans: ARL-8 localized primarily to lysosomes, and a deletion mutant of arl-8 displayed an increase in number of lysosomes that were small in size and non-a … More cidic. Extracellular macromolecules were endocytosed and transported through endosomes in arl-8 mutant coelomocytes, but its degradation was markedly reduced. Thus, Arl8 appeared to function as an important regulator of lysosome biogenesis/function.2. Rab45 is an atypical GTPase that contains a coiled-coil motif at the mid region and a distinct N-terminal EF-hand domain with C-terminal Rab-homology domain. Rab45 was capable of self-interacting, and the self-interaction required the mid region containing the coiled-coil motif. Rab45 expressed in HeLa cells was localized in a small patch in the perinuclear area of the cell, and the localization was regulated by the guanine nucleotide-bound states of Rab45. The mid region, together with Rab domain, appeared to be essential for the characteristic perinuclear localization of Rab45.3. Di-Ras, which belongs to a distinct branch of the Ras family, existed predominantly as a GTP-bound form in living cells. The expression of Di-Ras was rather specific in neuronal cells, and its over-expression induced apoptotic cell death with DNA fragmentation in neuronal cells. A deletion mutant of arl-8 in C. elegans displayed a phenotype that acetylcholine release from nerve cells might be impaired. Less

G 蛋白在 GTP 和 GDP 结合状态的两种不同构象之间循环，在许多细胞内信号传导途径中作为“分子开关”发挥着重要作用。 G 蛋白家族包括 1) 参与蛋白质合成和 mRNA 降解的翻译因子。，2) 三聚体 G 蛋白，和 3) 小 GTP 酶小 GTP 酶，如 Ras、Rab、Arf 和 Rho/Rac 家族，参与细胞内生长和分化的调节。然而，还有许多其他小 GTP 酶，其功能尚不清楚。在本研究中，我们鉴定并表征了具有独特生化特性或组织表达的新型小 GTP 酶。对于秀丽隐杆线虫巨噬细胞样体腔细胞中溶酶体的生物合成至关重要：ARL-8 主要定位于溶酶体，而 ARL-8 的缺失突变体arl-8 表现出尺寸较小且非酸性的溶酶体数量增加，细胞外大分子被内吞并通过 arl-8 突变体腔细胞的内体转运，但其降解明显减少。 Rab45 是溶酶体生物发生/功能的重要调节因子，是一种非典型 GTP 酶，其中部包含卷曲螺旋基序和不同的 N 端 EF-hand 结构域与 C 端 Rab-同源结构域能够自我相互作用，并且自我相互作用需要包含在 HeLa 细胞中表达的卷曲螺旋基序的中间区域。细胞核周区域的小斑块，其定位受 Rab45 的鸟嘌呤核苷酸结合状态调节，中间区域与 Rab 结构域一起似乎是对于 Rab45.3 的特征性核周定位至关重要，Di-Ras 属于 Ras 家族的一个独特分支，主要以 GTP 结合形式存在于活细胞中。Di-Ras 的表达在神经元细胞中具有相当的特异性。，其过度表达会导致神经元细胞中的 DNA 断裂，导致细胞凋亡。秀丽隐杆线虫中 arl-8 的缺失突变体表现出神经细胞释放乙酰胆碱可能受到损害的表型。较少的