Dynamic Regulation of Neurotransmitter Release

描述(申请人提供)：阐明突触可塑性的分子基础将导致对神经回路修饰的更复杂的理解，神经回路修饰是健康和疾病中经验依赖性可塑性的基础。关于突触后形式的长时间可塑性的机制，人们知道得很多。然而，相比之下，人们对突触前可塑性的机制知之甚少。这一建议侧重于了解一类突触前活动区蛋白RIMS的突触功能，因为它们需要一种突出的突触前LTP形式，以及它们在基础神经递质释放和短期可塑性中的额外作用。RIMS有几个蛋白质结合域，它们与突触小泡和活动区的关键成分相互作用。正因为如此，RIMS被描述为突触前“支架”蛋白。作为一个支架，RIM是一个强大的工具，可以深入了解几个重要的突触前蛋白的协调活动。一个关键的悬而未决的问题是了解RIM如何整合其结合伙伴的活动来实现突触可塑性。在这个提案中，我们将在RIM1a基因敲除背景下进行救援实验，以描绘RIM1a与其他突触前蛋白相互作用的功能意义。我们还将研究一个关键的PKA磷酸化位点的功能意义，该位点与介导LTP有关。最后，我们将评估RIM2基因产物的功能意义。它们在功能上是多余的，还是特定RIM亚型的表达表达了不同的突触属性？为了进行这些实验，我们将在培养和急性切片准备上使用电生理记录技术，并结合分子技术允许基因转移到基因敲除背景中。准确了解突触前可塑性背后的分子相互作用对于研究突触前可塑性的行为学意义以及针对这些蛋白开发治疗可能涉及突触可塑性的广泛神经精神疾病，如痴呆、肌张力障碍和成瘾都是至关重要的。

DESCRIPTION (provided by applicant): Elucidating the molecular basis of synaptic plasticity will lead to a more sophisticated understanding of the neural circuit modifications which underlie experience-dependent plasticity in both health and disease. Much is known about the mechanisms of postsynaptic forms of long lasting plasticity. By comparison, however, relatively little is known about the mechanisms of presynaptic plasticity. This proposal focuses on understanding the synaptic functions of a class of presynaptic, active zone proteins, RIMs, because of their requirement in a prominent form of presynaptic LTP and their additional roles in basal neurotransmitter release and short-term plasticity. RIMs have several protein binding domains that interact with key components of synaptic vesicles and active zones. Because of this, RIMs have been described as presynaptic "scaffold" proteins. As a scaffold, RIM is a powerful tool to gain insight to the coordinate activities of several important presynaptic proteins. A key outstanding question is to understand how RIM integrates the activities of its binding partners to achieve synaptic plasticity. In this proposal, we will perform rescue experiments in the RIM1a knockout background to delineate the functional significance of RIM1a's interactions with other presynaptic proteins. We will also study the functional significance of a key PKA phosphorylation site that is implicated in mediating LTP. Lastly, we will evaluate the functional significance of the RIM2 gene products. Are they functionally redundant or does expression of a particular RIM isoform convey distinct synaptic properties? To perform these experiments we will use electrophysiological recording techniques on both culture and acute slice preparations in combination with molecular techniques to allow gene transfer into the knockout background. A precise understanding of the molecular interactions that underlie presynaptic plasticity as described in this proposal is critical both to enable studies of the behavioral significance of presynaptic plasticity and to enable targeting these proteins for the development of therapies for a wide range of neuropsychiatric diseases that may involve synaptic plasticity such as dementia, dystonia and addiction.