EXPRESSION OF THE NA-CA EXCHANGER IN DIVERSE TISSUES - A STUDY USING THE CLONED HUMAN CARDIAC NA-CA EXCHANGER
EXPRESSION OF THE NA-CA EXCHANGER IN DIVERSE TISSUES - A STUDY USING THE CLONED HUMAN CARDIAC NA-CA EXCHANGER
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DOI：
10.1152/ajpcell.1992.263.6.c1241
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发表时间：
1992-12-01
影响因子：
--
通讯作者：
SCHULZE, DH
中科院分区：
文献类型：
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作者：
KOFUJI, P;HADLEY, RW;SCHULZE, DH
在包括心肌细胞在内的许多细胞中，细胞质Ca主要受质膜Na-Ca交换器控制（3，8）。组织的多样性和细胞环境的差异提出了一个问题，即是否在所有组织中发现了相同的交换剂。最近的实验表明，使用杆细胞至少有两种形式的钠依赖性钙运输存在。我们已经研究了这个问题，在各种大鼠和人体组织中使用克隆的人心脏钠钙交换器cDNA。北方印迹分析表明，这两个物种的钠钙交换器的主要转录本是7.2磷酸酶在心脏，脑，肾，肝，胰腺，骨骼肌，胎盘和肺。此外，大鼠中的核糖核酸酶保护分析显示，在心脏、脑、肾、骨骼肌和肝脏中测试的348个碱基对片段是保守的。此外，Southern印迹分析表明，一个单一的基因编码这种钠钙交换。最后，我们表明，用于生成我们的探针的克隆编码一个完全功能的钠钙交换。用克隆的人心脏钠钙交换体转染COS细胞和293细胞，检测钠钙交换体的钙转运特性、电压依赖性和钠离子依赖性。我们的结论是，心脏形式的钠钙交换器是完全功能的cDNA在哺乳动物细胞系中表达时，而且，这种“心脏”形式的钠钙交换器是自然表达在所有人类和大鼠组织测试（但在不同的水平）。
In many cells including cardiac myocytes, cytoplasmic Ca is importantly controlled by the plasmalemmal Na-Ca exchanger (3, 8). The tissue diversity and differences in cellular environment raise the question whether the same exchanger is found in all tissues. Recent experiments using rod cells have demonstrated that at least two forms of Na-dependent Ca transport exist. We have examined this issue in various rat and human tissues using the cloned human cardiac Na-Ca exchanger cDNA. Northern blot analysis in these two species show that the major transcript of the Na-Ca exchanger is 7.2 kilobases in heart, brain, kidney, liver, pancreas, skeletal muscle, placenta, and lung. Furthermore, ribonuclease protection analysis in rats shows conservation of the 348-base pair segment tested in heart, brain, kidney, skeletal muscle, and liver. Additionally, Southern blot analysis suggests that a single gene encodes this Na-Ca exchanger. Finally, we show that the clone used to generate our probes encodes a completely functional Na-Ca exchanger. With the use of COS cells and 293 cells transfected with the cloned human cardiac Na-Ca exchanger, we tested the Ca transport properties of the Na-Ca exchanger, the voltage dependence of the Na-Ca exchanger, as well as the Na dependence of the transport function of the Na-Ca exchanger. We conclude that the cardiac form of the Na-Ca exchanger is completely functional when the cDNA is expressed in mammalian cell lines, and, furthermore, this ''cardiac'' form of the Na-Ca exchanger is naturally expressed in all human and rat tissues tested (but at varying levels).