Billing-Marczak Katarzyna, Ziemińska Elzbieta, Leśniak Wiesława, Łazarewicz Jerzy W, Kuźnicki Jacek
Department of Molecular and Cellular Neurobiology, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093 Warsaw, Poland.
Biochim Biophys Acta. 2004 Apr 16;1678(1):14-21. doi: 10.1016/j.bbaexp.2004.01.004.
Calretinin (CR) is an EF-hand calcium binding protein expressed in a tissue-specific manner. CR gene is active in some neurons, such as cerebellar granule neurons and in some tumor cells such as colon adenocarcinoma or epithelial mesothelioma. Our aim was to understand the mechanism(s) involved in tissue-specific regulation of CR gene transcription. Our recent paper showed that an "AP2-like" sequence located between -90/-80 bp of the CR gene promoter is important for specific expression of this gene in neurons differentiating from DEV multipotent cells [Biochim. Biophys. Acta (1577) 2000 412]. We now show by electrophoretic mobility shift assay (EMSA) that in cerebellar granule neurons, there is a nuclear protein that interacts with the "AP2-like" sequence. This interaction results in an increased CR gene promoter activity. In contrast, the "AP2-like" sequence does not play such a role in regulation of the CR gene transcription in adenocarcinoma and mesothelioma cancer cells. In these cells mutation in the "AP2-like" element did not affect transcriptional activity of the CR gene promoter and no protein binding to this element was observed by EMSA. These data clearly show that expression of CR gene in neurons and cancer cells is regulated by different mechanisms. On the other hand, in both cell types, the activity of CR gene promoter can be stimulated by zinc ions.
钙视网膜蛋白（CR）是一种以组织特异性方式表达的EF手型钙结合蛋白。CR基因在一些神经元中活跃，如小脑颗粒神经元，以及在一些肿瘤细胞中活跃，如结肠腺癌或上皮性间皮瘤。我们的目的是了解参与CR基因转录组织特异性调控的机制。我们最近的论文表明，位于CR基因启动子-90/-80 bp之间的一个“类AP2”序列对于该基因在从DEV多能细胞分化而来的神经元中的特异性表达很重要[《生物化学与生物物理学报》（1577）2000 412]。我们现在通过电泳迁移率变动分析（EMSA）表明，在小脑颗粒神经元中，有一种核蛋白与“类AP2”序列相互作用。这种相互作用导致CR基因启动子活性增加。相反，“类AP2”序列在腺癌和间皮瘤癌细胞中对CR基因转录的调控中不发挥这样的作用。在这些细胞中，“类AP2”元件的突变不影响CR基因启动子的转录活性，并且通过EMSA未观察到有蛋白与该元件结合。这些数据清楚地表明，CR基因在神经元和癌细胞中的表达受不同机制调控。另一方面，在这两种细胞类型中，CR基因启动子的活性都可以被锌离子刺激。
