Mutant Analysis of a Novel High Conductance K+ Channel

描述(申请人提供)：一种比较基因组方法，开始于对线虫中不寻常的slo-2基因的分析，导致了对长期追求的哺乳动物Na+激活的钾通道(KNA)的分子鉴定。KNA通道已经在心肌细胞和神经元中被发现，它们可能是抵抗缺血的重要保护机制(Dryer，1994)。我们的研究表明，线虫基因slo-2也具有耐缺氧能力(袁等人提交)。我们的研究进一步表明哺乳动物的KNA通道是由rSlack基因(Joiner，et al，1998)(Rslo2)编码的，rslo2是线虫slo-2基因的哺乳动物同源基因。我们证明了rSLO-2通道具有天然KNA通道的所有属性。我们现在计划通过研究SLO-2通道在不同类别的已鉴定神经元中的作用(在线虫中)，克隆存在于人类(和小鼠)基因组中的两个不同的哺乳动物SLO-2基因并从功能上鉴定这些发现，并确定哺乳动物SLO-2通道中负责感知Na+和CI-的显著特性的结构区域。除了扩展我们对离子通道激活相关因素的理论理解外，这些信息可能对临床应用也很重要。 调节KNA通道的药物，特别是通道开放剂，可能在预防心肌缺血和中风时的细胞损伤方面发挥有用的作用，并可能在移植过程中用作器官预处理的保护剂。

DESCRIPTION (provided by applicant): A comparative genomic approach, which began with the analysis of the unusual slo-2 gene in C. elegans has led to the molecular identification of the long sought-after mammalian Na+-activated potassium channel (KNa). KNa channels have been identified in cardiomyocytes and neurons where they may serve as an important protective mechanism against ischemia (Dryer, 1994). Our studies showed that the C. elegans gene, slo-2, also confers resistance to hypoxia (Yuan et al, submitted). Our studies further showed that mammalian KNa channels are encoded by the rSlack gene (Joiner, et al, 1998) (rslo2), a mammalian orthologue of the C. elegans slo-2 gene. We showed that rSLO-2 channels have all the properties of native KNa channels. We now plan to follow up on these findings by investigating the role of SLO-2 channels in different classes of identified neurons (in C. elegans), cloning and functionally characterizing two distinct mammalian slo-2 genes present in human (and mouse) genomes, and defining the structural regions in mammalian SLO-2 channels which are responsible for the salient property of sensing Na + and CI-. In addition to extending our theoretical understanding of the factors involved in ion channel activation, this information may be important for clinical applications. Pharmacological agents which modulate the KNa channel, especially channel openers, might serve a useful role in preventing cell damage during cardiac ischemia and stroke, and may serve as a protective agent in the pretreatment of organs used in transplant procedures.