Astrocyte dysfunction in epileptogenesis: the role of adenosine

描述（由申请人提供）：星形胶质细胞功能障碍在癫痫发生中的作用：腺苷项目摘要/摘要该资助提案研究了星形胶质细胞增生和由此产生的基于腺苷的神经调节功能障碍是癫痫发生（即癫痫发生）的机制原因的假设。这一点很重要，因为迄今为止还没有有效的癫痫预防措施。本研究将探讨癫痫持续状态（SE）引发的癫痫发生和小鼠内源性腺苷癫痫控制系统的功能障碍，以寻找星形胶质细胞为基础的癫痫发生机制，从而为开发新型抗癫痫治疗提供基础。该提议基于以下发现：（i）腺苷激酶（ADK）是调节腺苷的关键酶;（ii）在成人脑中，ADK在星形胶质细胞中表达;（iii）星形胶质细胞增生是癫痫发生的标志;（iv）ADK在癫痫星形胶质细胞海马内过度表达;（v）通过植入腺苷释放细胞增加腺苷可预防点燃癫痫发作。(vi)ADK的转基因过表达增加癫痫发作的易感性;（vii）ADK在转基因小鼠中的局部减少可预防癫痫发生。我们的中心假设是癫痫发生触发事件（例如SE）诱导星形胶质细胞增生，导致ADK区域上调，作为癫痫发生的必要组成部分，并且干细胞衍生的脑植入物重建脑腺苷可以预防这种癫痫发生。解决这一假设的模型系统包括杏仁核内应用红藻氨酸（KA），以启动癫痫选择性在小鼠海马结构的CA 3区和移植ADK缺陷的腺苷释放胚胎干细胞（ES）到癫痫区域。具体目标：在目的1中，我们将研究因果关系，时间和空间的关系星形胶质细胞增生，ADK的上调和癫痫发作的小鼠模型CA 3选择性癫痫。在目标2中，我们将使用一组不同的Adk转基因小鼠，其中我们可以从分子上分离ADK表达的细胞类型特异性功能与星形胶质细胞增生，以独立地研究这两种机制。在目标3中，我们将使用ADK缺陷的ES细胞衍生的海马内植入物用于预防癫痫发生的治疗方法。这些研究的预期结果是将星形胶质细胞ADK定义为预防癫痫发作的靶点，并将这些发现转化为一种新的基于干细胞的治疗方法。公共卫生相关性：目前，没有可用的治疗方法来预防癫痫的发展。该提案研究了大脑自身基于腺苷的癫痫控制系统的缺陷功能作为癫痫的机械原因，并将这些发现转化为通过植入腺苷释放干细胞来预防癫痫的新方法。

DESCRIPTION (provided by applicant): Astrocyte dysfunction in epileptogenesis: the role of adenosine Project Summary/Abstract This grant proposal studies the hypothesis that astrogliosis and resulting dysfunction of adenosine-based neuromodulation is a mechanistic cause for the development of epilepsy (i.e. epileptogenesis). This is of importance, since to date no effective prophylaxis for epilepsy is available. This proposal will explore status epilepticus (SE)- triggered epileptogenesis and dysfunction of the endogenous adenosine-based seizure control system in mice in search for an astrocyte-based mechanism of epileptogenesis and thus may provide a foundation for the development of novel antiepileptogenic therapies. The proposal is based on the following findings: (i) Adenosine kinase (ADK) is the key enzyme for the regulation of adenosine; (ii) In adult brain, ADK is expressed in astrocytes; (iii) Astrogliosis is a hallmark of epileptogenesis; (iv) ADK is over-expressed within epileptic astrogliotic hippocampus; (v) Augmentation of adenosine by implants of adenosine releasing cells prevents kindled seizures. (vi) Transgenic overexpression of ADK increases seizure susceptibility; (vii) Local reduction of ADK in transgenic mice prevents epileptogenesis. Our CENTRAL HYPOTHESIS is that an epileptogenesis triggering event (e.g. SE) induces astrogliosis with resultant regional upregulation of ADK as a necessary component of epileptogenesis and that reconstitution of brain adenosine by stem cell derived brain implants can prevent such epileptogenesis. The model system to address this hypothesis consists of intraamygdaloid application of kainic acid (KA) to initiate epileptogenesis selectively in the CA3 area of the hippocampal formation of mice and to transplant ADK-deficient adenosine releasing embryonic stem (ES) cells into the epileptogenic region. SPECIFIC AIMS: In Aim 1 we will study the causal, temporal, and spatial relations of astrogliosis, upregulation of ADK and seizures in a mouse model of CA3-selective epileptogenesis. In Aim 2 we will use a panel of different Adk-transgenic mice, in which we can molecularly separate cell-type specific functions of ADK expression from astrogliosis, to study both mechanisms independently. In Aim 3 we will use ADK-deficient ES cell-derived intrahippocampal implants in a therapeutic approach to prevent epileptogenesis. The expected outcome of these studies is to define astrocytic ADK as a target for the prevention of epileptic seizures and to translate these findings into a novel stem cell based treatment approach. PUBLIC HEALTH RELEVANCE: Currently, no therapy is available to prevent the development of epilepsy. This proposal studies a defective function of the brain's own adenosine-based seizure control system as a mechanistic cause for epilepsy and translates these findings into a novel approach to prevent epilepsy by implanting adenosine releasing stem cells.