Nuclear localization of diacylglycerol kinase ζ in neurons
Nuclear localization of diacylglycerol kinase ζ in neurons
复制标题
DOI：
10.1046/j.1460-9568.2003.02871.x
复制
发表时间：
2003-09-01
影响因子：
3.4
通讯作者：
Goto, K
中科院分区：
文献类型：
--
作者：
Hozumi, Y;Ito, T;Goto, K
二酰基甘油激酶（DGK）作为二酰基甘油水平的调节剂参与细胞内信号转导，从而导致蛋白激酶C的激活。先前的研究表明，DGK在哺乳动物物种中由一个同工酶家族组成，并且大多数（如果不是全部）在中枢神经系统中大量表达，这表明该酶在神经元功能中的重要性。在同工酶中，DGKzeta（以前在大鼠克隆中也被称为DGK-IV）具有独特的结构特征，如四个锚蛋白样重复序列和一个核定位信号（NLS），并且在嗅球、海马和大脑和小脑皮层的神经元中显示出强烈的mRNA表达(Goto， K. & Kondo， H. (1996), Proc. Natl Acad. Sci。美国，93,11196-11201)。然而，关于DGKzeta是否定位于这些细胞的细胞核，先前的研究给出了相互矛盾的结果。在这项研究中，我们使用了免疫组织化学与脑组织特异性抗体和cDNA转染到原代培养的神经元来解决这个问题。我们已经证明，虽然DGKzeta主要是神经元中的核蛋白，但在某些情况下它也可以是细胞质，并且亚细胞位置不仅取决于细胞类型，还取决于细胞的发育状态或生长条件。此外，我们利用缺失突变体表明DGKzeta的核转运依赖于NLS和c -末端区域（包括锚蛋白重复）之间的合作相互作用，这表明NLS是一个隐秘的位点，其暴露受c -末端区域的调节。综上所述，这些结果支持DGKzeta的定位可能受到这些与其c端区相互作用的不同蛋白质的差异表达的调节。
Diacylglycerol kinase (DGK) is involved in intracellular signal transduction as a regulator of levels of diacylglycerol which leads to protein kinase C activation. Previous studies have revealed that DGK consists of a family of isozymes in mammalian species and that most if not all of them show abundant expression in the central nervous system, suggesting the importance of this enzyme in neuronal function. Among the isozymes, DGKzeta (previously also known as DGK-IV for the rat clone) has unique structural features, such as four ankyrin-like repeats and a nuclear localization signal (NLS), and shows intense mRNA expression in neurons of the olfactory bulb, hippocampus and cerebral and cerebellar cortices (Goto, K. & Kondo, H. (1996), Proc. Natl Acad. Sci. USA, 93, 11196-11201). However, previous studies have given conflicting results about whether or not DGKzeta localizes to the nucleus in these cells. In this study, we have used immunohistochemistry with specific antibodies in brain tissues and cDNA transfection into primary cultured neurons to address this question. We have shown that, while DGKzeta is primarily a nuclear protein in neurons, it can also be cytoplasmic in some conditions, and the subcellular location depends not only on the cell type but also on the developmental state or growth conditions of the cell. In addition, we have used deletion mutants to show that nuclear transport of DGKzeta depends on a cooperative interaction between the NLS and the C-terminal region including ankyrin repeats in a manner which suggests that the NLS is a cryptic site whose exposure is regulated by the C-terminal region. Together, these results support the hypothesis that the localization of DGKzeta may be regulated by differential expression of these various proteins which interact with its C-terminal region.