Expression of translationally controlled tumour protein is regulated by calcium at both the transcriptional and post-transcriptional level
Expression of translationally controlled tumour protein is regulated by calcium at both the transcriptional and post-transcriptional level
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DOI：
10.1042/0264-6021:3420683
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发表时间：
1999-09-15
影响因子：
4.1
通讯作者：
Taylor, JA
中科院分区：
文献类型：
--
作者：
Xu, AM;Bellamy, AR;Taylor, JA
我们已经研究了如何改变蛋白质合成的程序在响应Cos-7细胞中使用的差异蛋白质组作图方法的钙稳态的损失。暴露的细胞的钙离子载体A23187或毒胡萝卜素，或替代地，表达的病毒糖蛋白报告耗尽细胞内钙储存，导致一组特征性的蛋白质的表达上调。其中之一是免疫控制的肿瘤蛋白（TCTP），一种细胞质蛋白，其表达以前没有被链接到钙扰动。定量北方印迹分析表明，在这些条件下，TCTP的稳态mRNA丰度也增加。通过向细胞中引入双-（邻氨基苯氧基）乙烷-N，N，N '，N'-四乙酸（BAPTA）来钳制细胞溶质钙浓度并不影响响应于离子载体而观察到的TCTP mRNA的稳态水平的增加。因此，内质网（ER）钙的耗竭，而不是胞浆钙浓度的升高，是负责增加TCTP基因的转录。然而，BAPTA的存在显著减弱了离子载体介导的蛋白质水平的增加。此外，TCTP在离子载体处理的细胞中的水平在相应的mRNA丰度的可检测的增加之前增加。这些结果表明，TCTP的表达在两个不同的水平上调节，以响应不同细胞区室中的钙浓度。而ER存储的耗尽导致TCTP mRNA丰度的增加，增加的胞质钙浓度在转录后水平调节基因表达。
We have investigated how the programme of protein synthesis is altered in response to a loss of calcium homoeostasis in Cos-7 cells using a differential proteome mapping approach. Exposure of the cells to the calcium ionophore A23187 or thapsigargin, or alternatively, expression of a viral glycoprotein reported to deplete intracellular calcium stores, resulted in the up-regulated expression of a characteristic set of proteins. One of these is the translationally controlled tumour protein (TCTP), a cytoplasmic protein whose expression has not previously been linked to calcium perturbation. Quantitative Northern blot assay demonstrated that steady-state mRNA abundance of TCTP was also increased under these conditions. Clamping the cytosolic calcium concentration by the introduction of bis-(o-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid (BAPTA) into cells did not affect the increase in steady-state levels of TCTP mRNA observed in response to ionophore. Therefore depletion of endoplasmic reticulum (ER) calcium, but not elevation of the cytosolic calcium concentration, was responsible for increased transcription of the TCTP gene. However, the presence of BAPTA significantly attenuated the ionophore-mediated increase in levels of the protein. Moreover, the level of TCTP in ionophore-treated cells increased in advance of a detectable increase in the corresponding mRNA abundance. These results indicate that expression of TCTP is regulated at two distinct levels in response to the concentration of calcium in different cellular compartments. Whereas depletion of the ER store causes an increase in TCTP mRNA abundance, increased cytosolic calcium concentrations regulate gene expression at the post-transcriptional level.