GABA (A) Receptor Subunit Regulation in Epileptogenesis

描述(申请人提供)：颞叶癫痫(TLE)是最常见的癫痫形式，经常是医学上难以治愈的。大量证据表明抑制性神经传递异常在TLE发病中起重要作用。GABAA受体是前脑中含量最丰富的抑制性神经递质受体，但对其在健康或疾病中的表达调控知之甚少。我们在成年大鼠癫痫持续状态(SE)后发现GABAR亚基表达的长期变化，包括A1亚基的减少，这与受体药理和功能的显著变化有关。此外，A1的变化高度依赖于SE发生的年龄，并与随后癫痫发展的可能性成反比。此外，我们发现，通过病毒介导的基因转移提高A1水平可以抑制SE后癫痫的发展。这些发现表明，DGN中A1水平的降低可能有助于癫痫的发生，而A1水平的升高可能具有保护作用。然而，要利用这种治疗潜力，需要了解GABAR A1亚单位的表达是如何调节的。因此，我们建议研究控制GABAR A1基因表达的潜在调控机制。我们将研究两个已确定的候选信号通路，cAMP反应元件结合蛋白(CREB)通路和糖皮质激素受体通路，在调节SE后GABAR A1亚单位表达中的作用。此外，使用生物信息学和蛋白质组学的组合，我们将对其他转录因子进行筛选，这些转录因子显示在SE之后与A1启动子的相互作用增强。拟议的研究有望阐明A1表达是如何调节的，以及这种调节在癫痫发生过程中是如何改变的。这些研究的结果应该有助于通过确定潜在的新的治疗靶点，特别是针对GABAR亚单位基因表达的调控，来开发预防或治愈癫痫的新疗法。

DESCRIPTION (provided by applicant): Temporal lobe epilepsy (TLE) is the most common form of epilepsy and is frequently medically intractable. There is abundant evidence that abnormalities in inhibitory neurotransmission play an important role in TLE. GABAA receptors (GABARs) are the most abundant inhibitory neurotransmitter receptors in forebrain, however, relatively little is known regarding regulation of their expression either in health or in disease. We have demonstrated long-term changes in expression of GABAR subunits, including decreases in the a1 subunit, in hippocampal dentate granule neurons (DGNs) following status epilepticus (SE) in adult rats, that are associated with marked changes in receptor pharmacology and function. Further, changes in a1 are highly dependent on the age at which SE occurs, and vary inversely with the likelihood of subsequent epilepsy development. In addition, we find that enhancing a1 levels using viral mediated gene transfer inhibits development of epilepsy after SE. These findings suggest that diminished a1 levels in DGN may contribute to epileptogenesis and that elevated a1 levels could be protective. To utilize this therapeutic potential, however, requires an understanding of how GABAR a1 subunit expression is regulated. We therefore propose to investigate potential regulatory mechanisms that control GABAR a1 gene expression. We will examine the role of two identified candidate signaling pathways, the cAMP response element binding protein (CREB) pathway and the glucocorticoid receptor pathway, in regulating GABAR a1 subunit expression following SE. Further, using a combination of bioinformatics and proteomics we will perform a screen for other transcription factors that show enhanced interaction with the a1 promoter after SE. The proposed studies are expected to elucidate how a1 expression is regulated and how this regulation is altered during epileptogenesis. Results of these studies should facilitate development of new therapies for the prevention or cure of epilepsy by identifying potential new therapeutic targets that specifically target regulation of GABAR subunit gene expression.