Mutants Showing SLO-1 Synaptic Mislocalization

描述(申请人提供)：大电导钙激活钾通道(BK通道，SLOL)是神经末梢的重要离子通道。BK通道与钙通道共同定位于突触前活动区，是神经递质释放的有力调节器。BK通道的功能受多种因素的调节，提示该通道在突触可塑性中可能起着重要作用。由于正确的亚细胞定位可能是BK通道功能的关键，因此确定BK通道突触定位是很重要的。明确BK通道突触靶向和定位的机制将是我们理解突触结构和功能的重要进展。 在线虫中，BK通道(SLO-1)功能缺失突变导致神经递质释放增加(Wang等人，2001年)，表明SLO-1的正常功能是下调释放。与其他物种的BK通道类似，SLO-1定位于神经系统的突触区域(Wang等人，2001年)。在修饰SLO-1羧基末端后，这种受限的分布模式在神经元中被改变为弥漫性表达。这一建议试图验证BK通道的突触前定位是由特定的运输和支架分子介导的假设。具体地说，将进行遗传筛选，以分离在线虫中显示GFP标记的SLO-1转基因错误定位的突变体。在随后的研究中，对这些突变体的分析可能有助于识别介导SLO-1突触靶向和定位的分子。

DESCRIPTION (provided by applicant): The large-conductance calcium-activated potassium channel (BK channel, Slol) is a prominent ion channel at nerve terminals. BK channels co-localize with calcium channels at the presynaptic active zone, and serve as a potent regulator of neurotransmitter release. The function of BK channels is regulated by many factors, suggesting that the channel is potentially an important player in synaptic plasticity. Since proper subcellular localization is likely critical for BK channel function, it is important to determine how BK channel synaptic localization is achieved. Defining the mechanism of BK channel synaptic targeting and localization would be a significant advance in our understanding of synaptic structure and function. In C. elegans, loss-of-function mutations of the BK channel (SLO-1) results in increased neurotransmitter release (Wang et al., 2001), suggesting that the normal function of SLO-1 is to downregulate the release. Similar to BK channels of other species, SLO-1 is localized to synaptic regions in the nervous system (Wang et al., 2001). This restricted distribution pattern was changed to diffuse expression in neurons following a modification of the SLO-1 carboxyl terminus. This proposal seeks to test the hypothesis that presynaptic localization of BK channels is mediated by specific transport and scaffold molecules. Specifically, a genetic screen will be performed to isolate mutants showing mislocalization of a GFP-tagged SLO-1 transgene in C. elegans. Analysis of these mutants in subsequent studies may allow the identification of molecules mediating SLO-1 synaptic targeting and localization.