Synaptic function of BK channel-interacting proteins

 描述(申请人提供)：突触前神经末梢是一个复杂的结构，包含许多控制神经递质释放的蛋白质。识别各种调节蛋白并阐明它们的作用机制对于了解突触前终末如何快速、动态地调节神经递质的释放至关重要。BK通道是一种高电导和电压/钙门控性钾通道，与电压门控性钙通道共同位于突触前终末，是神经递质释放的强大负调节因子。为了确定神经递质释放的新调节因子，采用遗传筛选的方法分离出了抑制线虫中由过度活跃的BK通道引起的昏睡表型的突变体。分离到BK通道相互作用蛋白的突变体bkip-2和bkip-4。BKIP-2和BKIP-4都有哺乳动物的同源物，但在大脑中的功能未知。初步研究表明，BKIP-2是神经元BK通道功能所必需的，而BKIP-4通过一种似乎独立于BK通道的机制来调节神经递质的释放。该建议的具体目的是：(1)验证BKIP-4通过控制突触前钙浓度来调节神经递质释放的假设；(2)确定BKIP-4突变是否改变神经解剖，以及BKIP-4功能在哺乳动物中是否保守；以及(3)确定BKIP-2如何调节突触前BK通道的功能。长期目标是回答各种突触前蛋白如何相互作用动态塑造神经回路，以及为什么这些蛋白的突变可能导致多种人类疾病的重要问题。

 DESCRIPTION (provided by applicant): The presynaptic nerve terminal is a complex structure containing many proteins that control neurotransmitter release. Identifying the various regulatory proteins and elucidating their mechanisms of action are critical to understanding how the presynaptic terminal regulates neurotransmitter release rapidly and dynamically. The BK channel, a high-conductance and voltage/calcium-gated potassium channel, colocalizes with voltage-gated calcium channels at the presynaptic terminal and serves as a powerful negative regulator of neurotransmitter release. To identify novel regulators of neurotransmitter release, a genetic screen was performed to isolate mutants suppressing a lethargic phenotype caused by a hyperactive BK channel in C. elegans. Mutants of bkip-2 and bkip-4 (bkip for BK channel Interacting Protein) were isolated. BKIP-2 and BKIP-4 both have mammalian homologues with unknown functions in the brain. Preliminary studies suggest that BKIP-2 is required for BK channel function in neurons whereas BKIP-4 regulates neurotransmitter release through a mechanism that appears to be independent of the BK channel. The specific aims of this proposal are: (1) test the hypothesis that BKIP-4 regulates neurotransmitter release through controlling presynaptic Ca2+ concentration; (2) determine whether BKIP- 4 mutation alters neural anatomy, and whether BKIP-4 function is conserved in mammals; and (3) determine how BKIP-2 regulates the function of presynaptic BK channels. The long-term goals are to answer the important questions how various presynaptic proteins interact to shape neural circuits dynamically and why mutations of these proteins may cause diverse human diseases.