Transcriptional Regulation of Potassium Current

Spitzer博士将分析胚胎脊髓神经细胞钾电流表达的分子机制。神经细胞通过电信号传递信息，并在分化的早期阶段获得产生动作电位的能力。最初，这些动作电位允许大量钙离子进入。斯皮策博士已经证明，这种钙流入会产生重要的信号，调节神经细胞发育的几个方面。然而，由于这种钙的进入对成熟的神经细胞是有毒的，神经元在成熟的过程中必须显著减少钙的进入量。在早期的工作中，斯皮策博士表明，钙流入的减少是钾电流增加的结果，钾电流通过称为钾通道的蛋白质孔流出神经细胞，反对钙流入。在这项资助的工作中，他将确定钾电流发育增加的基础。初步结果表明，一种被称为Kv2.2的特定基因的表达可能是钾电流增加的原因。Kv2.2编码构成钾通道的蛋白质。斯皮策博士将使用反义DNA序列来抑制分离和培养的神经细胞中蛋白质的合成。他将利用一种毒素，一种特殊的通道阻断剂，来检查这些实验的成功与否。如果反义处理抑制Kv2.2蛋白的表达，毒素将不再影响钾电流。该项目的结果将提供有关脊髓兴奋性调节的新知识。幼龄脊椎动物的中枢神经系统特别容易受到癫痫发作活动的影响，这一事实可能部分是由于钙的流入，这是早期信号机制的一部分。在未来，可能有可能通过调节特定钾通道基因的表达来选择性地抑制这种钙流入。

PI: Spitzer IBN: 9603978 Dr. Spitzer will analyze the molecular mechanisms that underlie expression of potassium current in embryonic spinal nerve cell. Nerve cells transmit information with electrical signals, and acquire the ability to generate these signals called action potentials at very early stages of differentiation. Initially, these action potentials allow the entry of substantial amounts of calcium ions. Dr. Spitzer has shown that this calcium influx generates important signals that regulate several aspects of the development of nerve cells. However, since this amount of calcium entry is toxic to mature nerve cells, the neurons must dramatically reduce the amount of calcium entry as they mature. In earlier work Dr. Spitzer showed that the reduction of calcium influx is the result of an increase in potassium current that flows out of the nerve cells through protein pores, called potassium channels, opposing the calcium influx. In the work supported by this grant he will determine the basis of the developmental increase in this potassium current. Preliminary results suggest that expression of a particular gene, known as Kv2.2, which encodes the protein of which potassium channels are composed, may be responsible for the increase in this potassium current. Dr. Spitzer will use antisense DNA sequences to suppress the synthesis of the protein in nerve cells isolated and growing in culture. He will take advantage of the availability of a toxin, hanatoxin, that is a specific blocker of these channels, to check the success of these experiments. If the antisense treatment suppresses expression of the Kv2.2 protein, the toxin will no longer affect the potassium current. The results from the project will provide new knowledge about the regulation of excitability in the spinal cord. The fact that the central nervous system of young vertebrates is especially vulnerable to epileptic seizure activity may be partly due to the calcium influx that is part of the early signaling mac hinery. In the future it may be possible to suppress this calcium influx selectively by regulating the expression of particular potassium channel genes.