Hormonal modulation of a communication signal

说明(申请人提供)：神经、肌肉、心脏和其他细胞的电兴奋性取决于离子通道。离子通道的突变会导致许多遗传性疾病。了解离子通道是如何调节的是一个重要的基础和临床科学目标。我们建议使用弱电鱼的通信信号作为模型系统来阐明离子电流是如何被调节的。电子器官放电(EOD)是一种性二态、激素敏感、个体不同的通讯信号。EOD的波形与电子器官中细胞膜的特性密切相关，也反映了这些特性，因为这些信号是神经系统的通货--电。我们已经证明，EOD脉冲的波形由Na+和K+电流决定，并且这些电流的生物物理性质是性别二态的、独立的和激素调制的。在最后一个授权期，我们克隆了三个K+通道基因，其中两个在雌性中高水平表达，在雄性中低水平表达，并且它们的水平被雄激素抑制。第三种基因在两性中表达相似，不受荷尔蒙的影响。我们还发现了一个独特的Na+通道基因。在这项提议中，我们继续关注K+和Na+电流的分子调控。具体目的1是利用亚基特异性通道阻滞肽、Western blotting和免疫沉淀以及辅助剂注射，研究这三种K+通道基因如何在K+电流动力学中产生观察到的变化。具体目标2是克隆和研究另外一个或多个候选K+通道基因的表达和可能的激素调节。具体目的3是：分离和测试K+通道β亚基在调节K+电流特性中的可能作用。具体目的4是研究Na+通道β亚基的两种剪接形式的差异表达和激素调节，以及不同的剪接形式如何影响Na+电流的失活率。

DESCRIPTION (provided by applicant): The electrical excitability of nerve, muscle, heart, and other cells depends on ion channels. Mutations of ion channels cause a number of inherited diseases. Understanding how ion channels are regulated is an important basic and clinical science goal. We propose to use the communication signals of a weakly electric fish as a model system to elucidate how ion currents are regulated. The electric organ discharge (EOD) is a sexually dimorphic, hormone-sensitive, and individually distinct communication signal. The wave shape of the EOD is intimately dependent on and reflective of the membrane properties of the cells in the electric organ because these signals are in the currency of the nervous system--electricity. We have shown that the wave shape of the EOD pulse is determined by Na+ and K+ currents and that the biophysical properties of these currents are sexually dimorphic, individually distinct, and hormonally modulated. In the last granting period we cloned three K+ channel genes from the electric organ and observed that two of them are expressed in high levels in females and low levels in males, and that their levels are suppressed by androgens. The third is expressed similarly in both sexes and is unaffected by hormones. We also discovered a unique Na+ channel gene. In this proposal we continue to focus on the molecular regulation of the K+ and Na+ currents. Specific aim 1 is to study how the three K+ channel genes generate the observed variation in K+ current kinetics using subunit-specific channel blocking peptides, Western blotting and immunoprecipitaiton, and acolyte injection. Specific aim 2 is to clone and the study the expression and 3ossible hormone regulation of one or more additional candidate K+ channel genes. Specific aim 3 is to: lone and test the possible role of K+ channel beta subunits in regulation of K+ current properties. Specific aim 4 is to study differential expression and hormonal regulation of two splice forms of a Na+ channel beta subunit, and how the different splice forms might influence the inactivation rate of the Na+ current.