SYNAPTIC ORIGINS OF CEREBELLAR DISEASE

描述(由申请者提供)：小脑是运动行为的基本部分。运动行为在共济失调、肌张力障碍和震颤中严重中断。这些疾病的定义是非常明显的运动障碍，这提出了一个有趣的问题，因为受影响的小脑电路在每种情况下都是相同的。例如，所有浦肯野细胞都接受相同的输入，但它们的输出却煽动了所有这三种疾病。这项研究的主要重点是了解相同的电路如何能够导致几种不同的疾病。为了解决这个问题，我们假设，在每种疾病中，神经回路的行为可能由神经元通讯如何改变来决定。为了测试这一点，我们设计了一个实验模型，使我们能够系统地阻止主要小脑突触中的化学交流。我们的模型利用Cre/loxP的遗传方法，有条件地阻断小鼠小脑每个主要突触上的囊泡状GABA转运体VGAT或囊泡状谷氨酸转运体VGLUT2的表达。我们已经产生了令人信服的初步数据，表明小脑疾病的开始可能取决于受损的突触，而不是电路。现在，我们想通过测试假设来扩展这项工作，该假设认为不同小脑突触信号的丢失将导致类似于一系列小脑疾病的表型。在我们的第一个目标中，我们将追踪典型信号通过小脑的路径，并系统地使每种类型的突触从感觉输入阶段到运动输出阶段保持沉默。我们将通过确定每个连接如何影响电路形态发生和神经元功能，以及每个连接如何影响运动行为，来描绘突触通信丢失如何导致运动疾病。在我们的第二个目标中，我们将测试在小脑发育期间阻止突触功能是否与阻止成年小脑中的相同突触具有不同的致病结果。对于这个问题，我们将在空间和时间上精确地操纵突触，然后分析行为小鼠的电路连接和神经元功能。这一信息对治疗具有重要的影响，因为不同的小脑突触可以针对不同疾病的运动进行抢救。

DESCRIPTION (provided by applicant): The cerebellum is essential for motor behavior. Motor behavior is severely disrupted in ataxia, dystonia, and tremor. These diseases are defined by very distinct motor impairments, which raises an intriguing problem because the cerebellar circuitry that's affected is the same in each case. For instance, all Purkinje cells receive the same inputs, yet their outputs instigate all three diseases. The main focus of this research is to understanding how the same circuitry is capable of causing several different diseases. To address this problem we postulated that in each disease circuit behavior might be determined by how neuronal communication is altered. To test this we devised an experimental model that enables us to systematically block chemical communication in the main cerebellar synapses. Our model utilizes the Cre/loxP genetic approach to conditionally block the expression of the vesicular GABA transporter VGAT or the vesicular glutamate transporter VGLUT2 at every major synapse in the mouse cerebellum. We have generated compelling preliminary data showing that the inception of cerebellar disease may depend on damaged synapses rather than circuits. Now we would like to expand on this work by testing the hypothesis that loss of signaling at different cerebellar synapses will result in phenotypes that resemble a range of cerebellar diseases. In our first aim we will trace the path of a typical signal through the cerebellum and systematically silence each type of synapse starting from the sensory input stage through to the motor output. We will delineate how loss of synapse communication leads to motor disease by determining how each connection influences circuit morphogenesis and neuronal function, and how each one impacts motor behavior. In our second aim we will test whether obstructing synapse function during cerebellar development has a different pathogenic outcome to blocking the same synapse in the adult cerebellum. For this question we will manipulate synapses with spatial and temporal precision and then analyze circuit connectivity and neuronal function in behaving mice. This information has important consequences for therapy because different cerebellar synapses could be targeted to rescue movement in different diseases.