ARX related Interneuron dysfunction and intractable pediatric epilepsy

描述（由申请人提供）：早期癫痫性脑病是一组以难治性癫痫发作、发育不良和6岁以下发病为特征的综合征。作为一名专门研究小儿癫痫的儿童神经学家，我花了很多临床时间为有这些症状的孩子的家庭提供咨询。我发现谈话是令人沮丧的，因为我告诉家属，我们的治疗方法不是为这些疾病设计的，几乎没有基础研究可以指导诊断和治疗。对早期难治性癫痫的进一步研究是迫切需要的。如果要在诊断和治疗方面取得进展，开发研究这些综合征的模型是必不可少的。近年来，发育转录因子aristaless-related homeobox基因（ARX）的突变已被证明可导致X连锁婴儿痉挛综合征和其他早期癫痫性脑病。我们的实验表明，选择性基因缺失的Arx在中间神经元（Arx CKO）的结果异常迁移的GABA能中间神经元，改变脑电图活动，和自发性癫痫发作。这些数据使我们假设，在条件性Arx小鼠中，中间神经元的早期损失改变了正常网络功能的发展，导致顽固性癫痫发作和认知功能障碍，从而模拟早期癫痫性脑病。这个建议既制定实验，以检查如何interneuron功能障碍导致癫痫发作和脑病的潜在病理生理过程，以及开发培训机会，以促进我过渡到职业生涯作为一个独立的研究者。为了研究Arx缺失如何导致癫痫发作和智力低下，我首先提出使用电压敏感染料成像技术来确定回路水平功能障碍的程度。接下来，我们将记录和比较对照和Arx CKO突变小鼠EEG的发展和皮层和海马节律期间的单个单位活动，以确定节律如何被中断以及涉及哪些中间神经元。这些研究将确定中断中间神经元的发育是否会改变绑定认知过程的正常节奏。最后，我们将使用一系列行为技术测试小鼠的认知功能，以提供将电路和网络水平功能障碍与小鼠的认知缺陷联系起来的证据。除了拟议中的实验，我还制定了一个计划，帮助我在费城儿童医院和宾夕法尼亚大学工作期间发展向独立过渡所需的技能。从这些研究中，我将学习两种技术，以实现在我未来的工作。这些研究还将为一个模型奠定基础，该模型将用于了解神经元间发育的改变如何导致早期癫痫性脑病。 公共卫生相关性：许多儿童在生命早期患有严重形式的癫痫，并继续发展医学难治性癫痫发作和严重的认知缺陷。最近，ARX（一种被认为控制中间神经元发育的蛋白质）的突变与X连锁癫痫发作和智力迟钝的家族有关。使用行为，脑电图和生理技术，我们将确定如何失去的ARX破坏正常的大脑功能，并导致癫痫发作和智力迟钝。

DESCRIPTION (provided by applicant): The early epileptic encephalopathies are a group of syndromes characterized by intractable seizures, poor developmental outcome, and onset before six years of age. As a child neurologist specializing in pediatric epilepsy, I spend much of my clinical time counseling families whose children have these conditions. I find the conversations to be frustrating as I inform the families that our treatments are not designed for these diseases and little basic research exists to guide diagnosis and treatment. There is a pressing need for further research into the early intractable epilepsies. Developing models to study these syndromes is essential if advances in diagnosis and treatment are to be made. Recently, mutations in the aristaless-related homeobox gene (ARX), a developmental transcription factor, have been shown to cause X-linked infantile spasms syndrome and other early epileptic encephalopathies. Our experiments have shown that selective genetic deletion of Arx in interneurons (Arx CKO) results in abnormal migration of GABAergic interneurons, altered EEG activity, and spontaneous seizures. These data lead us to hypothesize that early loss of interneurons, in conditional Arx mice, alters the development of normal network function leading to intractable seizures and cognitive dysfunction modeling the early epileptic encephalopathies. This proposal both formulates experiments to examine the underlying pathophysiological processes of how interneuron dysfunction leads to seizures and encephalopathy as well as develops training opportunities to facilitate my transition to a career as an independent investigator. To study how Arx loss leads to seizures and mental retardation I first propose to determine the extent of circuit level dysfunction using a voltage sensitive dye imaging technique. Next, we will record and compare the development of control and Arx CKO mutant mice EEG and single unit activity during cortical and hippocampal rhythms to determine how rhythms are interrupted and which interneurons are involved. These studies will ascertain if interrupting interneuronal development alters the normal rhythms that bind cognitive processes. Finally, we will test the cognitive function of the mice, using a battery of behavioral techniques, to provide evidence linking circuit and network level dysfunction to the cognitive deficits of the mice. In addition to the proposed experiments, I have created a plan to help develop the skills needed for my transition to independence while working at the Children's Hospital of Philadelphia and the University of Pennsylvania. From these studies I will learn two techniques to implement in my future work. These studies will also set the foundation of a model to be used to understand how alterations in interneuronal development lead to an early epileptic encephalopathy. PUBLIC HEALTH RELEVANCE: Many children are stricken with a severe form of epilepsy early in life and go on to develop medically refractory seizures and severe cognitive deficits. Recently, mutations in ARX, a protein believed to control how interneurons develop, have been linked to families with an X-linked pattern of seizures and mental retardation. Using behavioral, EEG, and physiological techniques we will determine how loss of ARX disrupts normal brain function and leads to seizures and mental retardation.