Cellular regulation of Sodium-activated Ion Channels

描述(申请人提供)：Slack和Slick基因编码Na+激活的K+通道，该通道调节神经元适应维持的突触刺激的速率和神经元动作电位的准确性。这些通道也被认为在保护神经元和心肌细胞免受缺氧性损伤中发挥关键作用。在它们的总体结构上，它们类似于其他电压门控K通道，但具有非常大的(&gt；600个氨基酸)细胞内C-末端。Slack的C末端结构域与脆性X智力低下蛋白(FMRP)相互作用，FMRP是一种RNA结合蛋白，调节神经元mRNA子集的运输和翻译。本应用程序中的工作将使用生化和电生理分析来确定Slack和FMRP在体外和体内相互作用中涉及的特定区域，并将确定FMRP需要哪些特定区域来控制Slack通道的门控。我们还将确定在脆性X综合征(Fmr1-/-)小鼠模型中Na+激活的K+通道的表达是如何改变的。特别是，我们将确定在Fmr1-/-动物中导致Slack远端C-末端完全丧失表达的机制，该区域似乎是FMRP与通道结合所必需的。平行的电生理学和药理学实验将评估这种改变的Slack表达模式对天然神经元中Na+激活的K+通道功能特性的影响。了解松弛和光滑通道的生物学特性和调节将有助于更清楚地理解脆性X综合征和相关疾病的缺陷，并有望导致新的治疗策略的开发。 与公共卫生相关：最近的证据表明，一类相对较新发现的蛋白质，称为钠激活钾通道，其激活受其与脆性X智力低下蛋白(FMRP)结合的调节。遗传性FMRP缺失或缺陷是遗传性智力障碍的主要原因。本应用中的实验将确定这种通道-FMRP相互作用的机制和生物学后果。这些信息将被用来评估这些通道是否有可能成为治疗有用的药物靶点，特别是，钠激活钾通道的药理操作是否可以克服一些伴随FMRP丢失的神经元活动障碍。

DESCRIPTION (provided by applicant): The Slack and Slick genes encode Na+-activated K+ channels, which regulate the rate at which neurons adapt to maintained synaptic stimulation and the accuracy of timing of neuronal action potentials. These channels have also been proposed to play a key role in the protection of neurons and cardiomyocytes from hypoxic injury. In their general structure, they resemble other voltage-gated K channels, but have very large (>600 amino acid) intracellular C-termini. The C-terminal domain of Slack interacts with Fragile- X Mental Retardation protein (FMRP), an RNA-binding protein that regulates trafficking and translation of a subset of subset of neuronal mRNAs. The work in this application will use biochemical and electrophysiological assays to determine the specific regions of Slack and FMRP involved in their interactions both in vitro and in vivo, and will determine which specific regions are required for FMRP to control the gating of Slack channels. We shall also determine how the expression of Na+-activated K+ channels is altered in a mouse model of Fragile X syndrome (Fmr1-/-). In particular we shall determine the mechanism that in Fmr1-/- animals causes the total loss of expression of the distal C- terminus of Slack, a region that appears to be required for FMRP binding to the channels. Parallel electrophysiological and pharmacological experiments will evaluate the effects of this altered pattern of Slack expression on the functional properties of Na+- activated K+ channels in native neurons. An understanding of the biological properties and regulation of Slack and Slick channels will lead to a clearer understanding of the deficits in Fragile X syndrome and related disorders and is expected to lead to the development of novel therapeutic strategies. PUBLIC HEALTH RELEVANCE: Recent evidence suggests that activation of a relatively newly discovered class of proteins, termed sodium- activated potassium channels is regulated by their binding to Fragile X Mental Retardation Protein (FMRP). Inherited loss or deficits in FMRP are the leading cause of inherited intellectual disorders. The experiments in this application will determine the mechanisms and biological consequences of this channel-FMRP interaction. This information will be used to evaluate whether these channels are likely to be therapeutically useful drug targets, and in particular, whether pharmacological manipulations of sodium-activated potassium channels can overcome some of the impairments in neuronal activity that accompany loss of FMRP.