Alpha2delta-mediated control of neuronal signaling

项目总结 细胞内钙离子驱动神经元信号和兴奋性，以及适当的空间和时间控制 的神经元钙信号是必需的，以防止大脑活动的失调控制，这可能导致 癫痫发作。神经元内钙的主要来源之一是通过电压门控钙通道进入。 在细胞膜上，然后通过共定位与不同的效应器机制偶联 神经元内的通道和钙反应蛋白。两种特定但不同的钙依赖 维持大脑动态平衡的关键过程包括逆行的内源性大麻素信号和 超极化后动作电位。内源性大麻素是由神经元在突触后产生的。 然后扩散到突触前终末，在那里它们与CB1受体和 有力地抑制大量突触的囊泡释放。另外，电压依赖性钙离子进入激活 邻近钙依赖性钾通道，介导动作电位后超极化 加速细胞复极化并控制神经元的放电率。对于这些现象中的每一种，都严格 钙离子进入到这些不同的效应器上的功能偶联对维持大脑功能至关重要。 而负责控制电压门控适当局部化的特定细胞机制 钙通道在很大程度上仍不为人所知，我们的初步数据表明，α2Delta在其中起着关键作用 钙离子进入效应器的功能偶联蛋白。这些辅助钙通道亚基有助于 交通电压门控钙通道至神经元表面膜，但在其他情况下仍保留 尽管与人类和小鼠的神经系统疾病有明显的联系，但仍是个谜。我们假设 Alpha2Delta蛋白是钙离子内流和钙离子之间功能偶联的关键介体。 大脑中的依赖信号。我们建议使用转基因小鼠和 电生理学方法确定α2β异构体在1)钙依赖逆行中的作用 从小脑浦肯野细胞到它们不同的突触输入的信号，2)兴奋性和 海马区的内源性大麻素信号，以及3)其背后的分子机制 使用分子置换策略的现象。总而言之，这些实验将导致一个巨大的 增强了对这类重要的钙通道亚单位功能的认识，我们认为 可以用来提高我们在以下情况下控制大脑失控兴奋性的能力 癫痫发作。

PROJECT SUMMARY Intracellular calcium drives neuronal signaling and excitability, and appropriate spatial and temporal control of neuronal calcium signals are required to prevent dysregulated control of brain activity, which can lead to epileptic seizures. One of the primary sources of calcium in neurons is entry via voltage-gated calcium channels on the cell membrane, which is then coupled to various effector mechanisms through co-localization of channels and calcium-responsive proteins within the neuron. Two specific, but distinct, calcium-dependent processes critical for maintaining brain homeostasis involve retrograde endocannabinoid signaling and the action potential afterhyperpolarization. Endocannabinoids are produced postsynaptically by neurons in a calcium-dependent manner, and then diffuse to presynaptic terminals where they bind to CB1 receptors and powerfully inhibit vesicle release at numerous synapses. Separately, voltage-dependent calcium entry activates nearby coupled calcium-dependent potassium channels, mediating the action-potential afterhyperpolarization which accelerates cell repolarization and controls neuronal firing rates. For each of these phenomena, tight functional coupling of calcium entry to these disparate effectors is critical in maintaining brain function. While the specific cellular mechanisms responsible for controlling the appropriate localization of voltage-gated calcium channels remain largely unknown, our preliminary data indicate a critical role for the alpha2delta proteins in the functional coupling of calcium entry to effectors. These auxiliary calcium channel subunits help traffic voltage-gated calcium channels to the neuronal surface membrane, but have otherwise remained enigmatic despite clear association with neurologic diseases in humans and mice. We hypothesize that the alpha2delta proteins are critical mediators of functional coupling between calcium entry and calcium- dependent signaling throughout the brain. We propose to use genetically modified mice and electrophysiological assays to define the roles of alpha2delta isoforms in 1) calcium-dependent retrograde signaling from cerebellar Purkinje cells to their various synaptic inputs, 2) the control of excitability and endocannabinoid signaling in the hippocampus, and 3) the molecular mechanisms underlying these phenomena using molecular replacement strategies. Together, these experiments will lead to a greatly enhanced appreciation of the function of this important class of calcium channel subunits, which we believe can be leveraged to improve our ability to control runaway excitability in the brain in conditions such as epileptic seizures.