Molecular bases of BK channel function and localization

描述(申请人提供)：BK通道几乎无处不在地表达，并执行许多重要的生理功能。通道功能障碍会导致多种疾病，包括癫痫、进行性听力损失、小脑性共济失调和高血压。BK通道的功能依赖于适当的亚细胞定位以及与辅助或调节蛋白的相互作用。然而，BK通道亚细胞定位的分子基础尚不清楚，对BK通道辅助/调节蛋白的了解也很有限。线虫强大的分子遗传学被用来识别对BK通道功能或亚细胞定位重要的蛋白质。在初步研究中，分离了三个基因的突变体(命名为bkip-1、bkip-2和bkip-3)，作为抑制由表达SLO-1的功能增益(Gf)亚型-线虫BK通道引起的昏睡表型。这些突变体的表型包括神经递质释放增加(bkip-1)和SLO-1错误定位(bkip-2和bkip-3)。BKIP-1和BKIP-2编码新的BK通道相互作用蛋白，而BKIP-3仍有待鉴定。当在异源表达系统中分析时，BKIP-1对SLO-1的功能特性有几个影响。这项提议是为了验证这三个BKIP对SLO-1功能和/或体内亚细胞定位重要的假设，以及线虫中存在其他功能相关的蛋白的假设。这项建议的具体目的是：(1)确定BKIP-1如何调控SLO-1功能；(2)确定BKIP-2和BKIP-3如何控制SLO-1亚细胞定位和/或功能；以及(3)分离和鉴定更多抑制SLO-1(Gf)引起的昏睡表型的突变体，这将在未来的研究中进行分析。长期目标是阐明BK通道功能和亚细胞定位的分子基础。公共卫生相关性：BK通道的突变会导致多种疾病，包括癫痫、高血压、进行性听力丧失、小脑性共济失调、膀胱过度活动、阴茎勃起功能障碍、肾小球滤过和K+排泄障碍以及阵发性运动障碍。建议的研究计划可能识别对BK通道功能和/或体内亚细胞定位重要的新蛋白质。这些信息对于了解BK通道相关疾病的分子基础，以及确定治疗和管理这些疾病的候选药理靶点具有潜在的重要价值。

DESCRIPTION (provided by applicant): BK channels are almost ubiquitously expressed and perform many important physiological functions. Dysfunction of the channel causes a variety of diseases, including epilepsy, progressive hearing loss, cerebellar ataxia, and hypertension. The function of BK channels depends on proper subcellular localization and interactions with auxiliary or regulatory proteins. However, the molecular basis of BK channel subcellular localization is unknown and only limited knowledge exists about BK channel auxiliary/regulatory proteins. The powerful molecular genetics of C. elegans is explored to identify proteins important to BK channel function or subcellular localization. In preliminary studies, mutants of three genes (named as bkip-1, bkip-2 and bkip-3) were isolated as suppressors of a lethargic phenotype caused by expressing a gain-of-function (gf) isoform of SLO-1, the C. elegans BK channel. Phenotypes of these mutants included increased neurotransmitter release (bkip-1) and SLO-1 mislocalization (bkip-2 and bkip-3). bkip-1 and bkip-2 were found to encode novel BK channel- interacting proteins whereas bkip-3 remains to be identified. BKIP-1 showed several effects on SLO-1 functional properties when analyzed in a heterologous expression system. This proposal is to test the hypotheses that the three BKIPs are important to SLO-1 function and/or subcellular localization in vivo and that there are other functionally related proteins in C. elegans. The specific aims of this proposal are: (1) determine how BKIP-1 regulates SLO-1 function; (2) determine how BKIP-2 and BKIP-3 control SLO-1 subcellular localization and/or function, and (3) isolate and identify additional mutants that suppress the lethargic phenotype caused by SLO-1(gf), which will be analyzed in future studies. The long-term goal is to elucidate the molecular basis of BK channel function and subcellular localization. PUBLIC HEALTH RELEVANCE: Mutations of the BK channel cause a variety of diseases, including epilepsy, hypertension, progressive hearing loss, cerebellar ataxia, overactive bladder, penile erectile dysfunction, impaired renal glomerular filtration and K+ excretion, and paroxysmal dyskinesia. The proposed research program may identify novel proteins that are important to BK channel function and/or subcellular localization in vivo. Such information is potentially of great value to understanding the molecular bases of BK channel-related diseases, and to identifying candidate pharmacological targets for the treatment and management of these diseases.