Cell Type-Specific Synaptic Defects in Angelman Syndrome Model Mice

Angelman综合征（AS）是一种自闭症谱系障碍，其特征是发育迟缓，缺乏语言和癫痫。 超过90%的AS患者存在癫痫发作，深刻影响了他们及其护理人员的生活质量。 AS是由UBE 3A基因缺失或突变引起的，AS模型小鼠携带UBE 3A无效突变。 尽管AS的癫痫发作易感性很高，但抑制性神经传递的异常在很大程度上尚未研究。 AS患者和模型小鼠也表现出异常的EEG节律和癫痫发作的新皮质起源，我建议，一个明确的抑制性突触缺陷在新皮质中发生在Ube 3a的情况下。 识别这种缺陷将为AS患者的癫痫治疗提供见解。 我将使用一个AS模型小鼠，并利用视觉皮层的良好表征的电路，以确定AS患者癫痫发作的突触基础。 AS模型小鼠（UBE 3A母体无效突变）表现出自发性和诱发性癫痫发作，尽管兴奋性突触减少。 这表明Ube 3a的缺失可能会导致抑制性神经传递的更深刻的损失。 为了测试这种可能性，我将首先采用体外电生理学测试参与Ube 3a在建立兴奋/抑制平衡的新皮层电路。 其次，我将使用电生理和病毒介导的基因表达的组合，以确定细胞类型特异性的贡献电路异常的AS大脑。 最后，我将确定抑制的丧失是否会导致体外和体内网络和癫痫发作活动的变化。 这些研究将证明皮质回路异常可能使AS个体易患癫痫。 在初步的实验中，我发现了靶细胞特异性抑制缺陷，这是AS新皮层抑制/兴奋失衡的基础。 我的数据第一次提出了为什么AS患者容易患癫痫的突触基础。

Angelman Syndrome (AS) is an autism spectrum disorder characterized by developmental delay, lack of speech, and epilepsy. Seizures are present in over 90% of AS patients, profoundly impacting their quality of life and that of their caregivers. AS is caused by deletion or mutation of the gene UBE3A, and AS model mice harbor a null mutation in UBE3A. Despite the high seizure susceptibility in AS, abnormalities in inhibitory neurotransmission have been largely unstudied. AS patients and model mice also exhibit abnormal EEG rhythms and seizures of neocortical origin, I propose that a well-defined inhibitory synaptic deficit in the neocortex occurs in the absence of Ube3a. Identifying such a deficit will provide insight into the treatment of epilepsy in AS individuals. I will use an AS model mouse and take advantage of the well-characterized circuitry of the visual cortex to determine the synaptic basis for the seizures in AS patients. AS model mice (UBE3A maternal null mutation) exhibit spontaneous and evoked seizures despite having a reduction in excitatory synapses. This suggests that the loss of Ube3a may cause an even more profound loss of inhibitory neurotransmission. To test this possibility, I will first employ in vitro electrophysiology to test the involvement of Ube3a in the establishment of excitatory/inhibitory balance in neocortical circuits. Second, I will use a combination of electrophysiological and viral-mediated gene expression to determine cell type-specific contributions to circuit abnormalities in the AS brain. Finally, I will determine if the loss of inhibition leads to changes in network and seizure activity in vitro and in vivo. These studies will demonstrate the cortical circuit abnormalities that may predispose AS individuals to epilepsy. In preliminary experiments, I have found target cell-specific deficits in inhibition that underlie an inhibitory/excitatory imbalance in the AS neocortex. My data suggest, for the first time, a synaptic basis for why individuals with AS are prone to epilepsy.