Role of the CaV2 channel in regulating transmitter release in Aplysia sensory neurons

CaV2 通道在调节海兔感觉神经元递质释放中的作用

• 批准号: RGPIN-2019-03951
• 负责人: Sossin, Wayne
• 金额: $ 4.23万
• 依托单位: McGill University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2022
• 资助国家: 加拿大
• 起止时间: 2022-01-01 至 2023-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=761359
• 关键词: Role; CaV2; channel; regulating; transmitter

Neurons communicate through synaptic connections and these synapses underlie most brain function. At synapses, the presynaptic cell releases neurotransmitter though calcium-dependent release of synaptic vesicles that contain the neurotransmitters. The post-synaptic cell then responds through neurotransmitter-gated ion channels. Importantly, many synaptic connections are specialized for specific brain functions and control transmitter release in unique ways. The synaptic connections between the sensory neuron and the motor neuron that underlie the simple defensive withdrawal reflexes of the marine mollusc Aplysia californica have long been used to study the mechanisms underlying the control of synaptic transmission. The reflexes habituate with repeated activation through reducing release of the neurotransmitter-containing synaptic vesicles at the sensory-to-motor neuron synapses, termed homosynaptic depression. The sensory neurons must have specializations that mediate this depression, since most synapses do not decrease their release of synaptic vesicles under these conditions. A noxious stimulus to the animal results in the recovery from depression and behavioral dishabituation of the reflexes. The reduction in transmitter release during homosynaptic depression is known to involve changes in the efficacy of calcium to trigger the release of neurotransmitter: a change in calcium-secretion coupling. However, the molecular mechanisms of both homosynaptic depression and how it is reversed remain unknown. Evidence from a wide variety of synapses suggests calcium-secretion coupling is regulated through interactions between the specific calcium channel, CaV2, the source of calcium that triggers neurotransmitter release, and the synaptic vesicle. In the present application we will examine whether different sensory neuron-specific modifications of CaV2 or of the proteins that link CaV2 to the synaptic vesicles underlie homosynaptic depression and its reversal. We will measure depression and its reversal at sensory-motor neuron synapses where the sensory neurons express a modified CaV2 that either lacks sensory-neuron specific splicing, or specific binding sites for proteins important for interacting with synaptic vesicles. We will also examine the effects of expressing proteins that link CaV2 to synaptic vesicles that are not normally expressed in sensory neurons. These experiments will identify why sensory neurons depress and how the reversal of depression is mediated. These results will determine how transmitter release is regulated at this specialized synapse and provide general answers to the question of how calcium-secretion coupling functions and how transmitter release can be specialized at specific synapses in order to optimize brain function.

神经元通过突触连接进行交流，这些突触是大多数大脑功能的基础。在突触处，突触前细胞通过含有神经递质的突触囊泡的钙依赖性释放来释放神经递质。然后突触后细胞通过神经递质门控离子通道做出反应。重要的是，许多突触连接专门用于特定的大脑功能，并以独特的方式控制递质释放。感觉神经元和运动神经元之间的突触连接是海洋软体动物加州龙蜥简单防御性退缩反射的基础，长期以来一直被用来研究突触传递控制的机制。通过减少感觉-运动神经元突触处含有神经递质的突触囊泡的释放，反射习惯于重复激活，称为同突触抑制。感觉神经元必须具有介导这种抑制的特化，因为大多数突触在这些条件下不会减少它们释放突触小泡。对动物的有害刺激导致从抑郁和反射的行为失调中恢复。已知同突触抑制期间递质释放的减少涉及钙触发神经递质释放的功效的变化：钙分泌偶联的变化。然而，同突触抑制的分子机制及其如何逆转仍不清楚。来自多种突触的证据表明，钙分泌偶联是通过特定的钙通道CaV 2（触发神经递质释放的钙源）和突触囊泡之间的相互作用来调节的。在本申请中，我们将研究是否不同的感觉神经元特异性修饰的CaV 2或连接CaV 2的突触囊泡的蛋白质的基础同源突触抑郁症及其逆转。我们将测量感觉运动神经元突触的抑郁症及其逆转，其中感觉神经元表达修饰的CaV 2，该修饰的CaV 2要么缺乏感觉神经元特异性剪接，要么缺乏与突触囊泡相互作用的重要蛋白质的特异性结合位点。我们还将研究表达蛋白质的影响，这些蛋白质将CaV 2与感觉神经元中通常不表达的突触囊泡联系起来。这些实验将确定为什么感觉神经元抑制以及如何介导抑郁的逆转。这些结果将确定如何在这个专门的突触调节递质释放，并提供一般性的答案，如何钙分泌耦合功能的问题，以及如何递质释放可以专门在特定的突触，以优化大脑功能。