Molecular characterization of a transport vesicle protein Neurensin-2, a homologue of Neurensin-1, expressed in neural cells
Molecular characterization of a transport vesicle protein Neurensin-2, a homologue of Neurensin-1, expressed in neural cells
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DOI：
10.1016/j.brainres.2006.01.085
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发表时间：
2006-04-07
期刊：
影响因子：
2.9
通讯作者：
Taketani, S
中科院分区：
文献类型：
--
作者：
Nakanishi, K;Ida, M;Taketani, S
我们分离并鉴定了一种新的cDNA，该cDNA编码一种小的神经元膜蛋白，其序列与neural -p24/Neurensin-1具有高度同源性，后者是一种在神经元小囊泡端含有微管相关结构域的蛋白质。新发现的Neurensin-2具有双膜跨越结构域，但不具有微管结合结构域，分子量为28 kDa。神经素-2 mRNA仅在大脑中表达，而该蛋白在出生后发育的小鼠的各种神经元中表达，包括丘脑/下丘脑和海马神经元。视黄酸暴露的小鼠神经母细胞瘤Neuro2a细胞中神经球蛋白-1 mRNA和蛋白水平升高，而神经球蛋白-2 mRNA和蛋白水平保持不变。将Neurensin-2 cDNA转染到Neuro2a细胞后，在核周溶酶体等小泡中表达Neurensin-2。在Neuro2a细胞中共转染Neurensin-1和-2 cDNA时，Neurensin-2主要存在于细胞体的小泡中，而Neurensin-1主要存在于生长锥的小泡中。在神经生长因子刺激的PC12细胞中，这些蛋白的细胞内定位也不同。此外，小鼠脑免疫化学染色显示，Neurensin-1和-2在对角带、海马、杏仁核、habenula核等许多区域分布相似，但在细胞内定位不同：Neurensin-1主要存在于神经突，而Neurensin-2存在于细胞体。因此，神经素-1和-2都定位于神经细胞的小泡中，但它们在小泡中的定位并不总是相同的，这表明它们受到不同的调控。
We have isolated and characterized a novel cDNA encoding a small neuronal membrane protein showing high sequence homology to Neuro-p24/Neurensin-1, a protein containing a microtubule-associated domain at the carboxyl-terminus and exclusively localized to small vesicles of neurons. The newly identified Neurensin-2 constitutes two-membrane spanning domains but not the microtubule-binding domain, with a molecular mass of 28 kDa. Neurensin-2 mRNA is expressed only in brain, whereas the protein expressed in various neurons including those of the thalamus/hypothalamus and hippocampus, of postnatally developing mice. While the levels of Neurensin-1 mRNA and protein in retinoic acid-exposed mouse neuroblastoma Neuro2a cells increased, those of Neurensin-2 mRNA and protein remained unchanged. When the Neurensin-2 cDNA was transfected into Neuro2a cells, Neurensin-2 was expressed in small vesicles including lysosomes in the perinuclear region. On the cotransfection of Neurensin-1 and -2 cDNA into Neuro2a cells, Neurensin-2 was mainly found in small vesicles of the cell body and Neurensin-1 in those of growth cones. In nerve growth factor-stimulated PC12 cells, the intracellular localization of these proteins also differed. Furthermore, immunochemical staining of mouse brain revealed that Neurensin-1 and -2 had a similar distribution in many regions such as the Diagonal band, hippocampus, amygdaloid nucleus, and habenula nucleus, but differed in the intracellular localization as follows: Neurensin-1 was found mainly in neuritic processes, while Neurensin-2 was found in cell bodies. Thus, both Neurensin-1, and -2 are localized in small vesicles in neural cells, but their localizations of the vesicles are not always the same by each other, suggesting that they are under separate regulation.