BDNF and JAK/STAT: partners in seizure-induced GABA-A receptor downregulation

描述(由申请人提供)： 癫痫是一种以反复发作为特征的神经疾病，全世界有超过5000万人受到影响。颞叶癫痫(TLE)是一种常见的癫痫形式，癫痫发作发生在颞叶。TLE可能会使人虚弱，因为许多患者经历了记忆功能受损和抑郁，或者由于意识丧失而遭受与癫痫相关的伤害。此外，每年有多达50,000人死于癫痫发作和相关原因。由于存在如此严重的健康风险，了解TLE背后的分子机制对于更好地治疗这种疾病非常重要。癫痫神经元在癫痫发作过程中表现出不同的活动，受神经递质控制，包括3-氨基丁酸(GABA)。A型GABA受体组成改变可能与癫痫易感性有关。特别是，在人类和TLE动物模型中，在长期癫痫发作后观察到14个亚基的上调和11个亚基的下调。我们的实验室已经发现脑源性神经营养因子(BDNF)是一种关键的调节因子，它通过激活Janus激酶(JAK)/信号转导和转录激活因子(STAT)途径来调节11的下调，该通路控制可诱导的cAMP早期抑制物(ICER)的表达。我们的一般假设是，BDNF信号通过JAK/STAT通路下调癫痫持续状态(SE)后11的表达，导致抑制功能受损，这在癫痫发生过程中起着关键作用。利用各种技术，包括在培养和体内的基因沉默，染色质免疫沉淀(ChIP)，以及蛋白质/蛋白质相互作用的免疫共沉淀，将识别由BDNF的前体或成熟形式激活的JAK/STAT信号通路的特定成分。我们还将确定神经营养素受体TrkB和p75NTR是否与JAK/STAT复合体直接相关，以及JAK/STAT激活在匹罗卡品TLE模型中对癫痫发生的潜在作用。所提出的研究为直接识别BDNF诱导的由SE激活的JAK/STAT通路的不同成员奠定了基础，并有望为未来治疗难治性癫痫以及其他表现为11个亚单位表达减少的疾病提供新的治疗靶点。 公共卫生相关性： 癫痫是一种神经系统疾病，全世界有5000多万人受到影响(癫痫基金会，2008年)。神经递质受体亚单位的改变可能有助于癫痫的一种形式--颞叶癫痫的发作易感性。拟议的研究将检查导致这些变化的信号通路，希望为更有效的癫痫治疗确定新的靶点。

DESCRIPTION (provided by applicant): Epilepsy is a neurological disorder characterized by recurrent seizures, affecting more than 50 million people worldwide. Temporal lobe epilepsy (TLE) is a common form of epilepsy, where seizures arise from the temporal lobe. TLE can be debilitating, as many patients experience impaired memory function and depression, or suffer seizure-related injuries due to loss of consciousness. Furthermore, up to 50,000 people die each year from seizures and related causes. With the potential for such serious health risks it is important to understand the molecular mechanisms behind TLE to better treat the disorder. Epileptic neurons exhibit distinct activity during seizures, controlled by neurotransmitters including 3-aminobutyric acid (GABA). Altered type A GABA receptor composition may contribute to seizure susceptibility. In particular, an upregulation of 14 and a downregulation of 11 subunits are observed after prolonged seizures in humans and in TLE animal models. Our laboratory has identified brain derived neurotrophic factor (BDNF) as a key regulator that mediates 11 downregulation through its activation of the Janus kinase (JAK)/ signal transducer and activator of transcription (STAT) pathway, that controls expression of inducible cAMP early repressor (ICER). Our general hypothesis is that BDNF signals through the JAK/STAT pathway to downregulate 11 expression after status epilepticus (SE), resulting in impaired inhibition that plays a critical role in the process of epileptogenesis. Using a variety of techniques including gene silencing in culture and in vivo, chromatin immunoprecipitation (ChIP), and co-immunoprecipitation of protein/protein interactions, specific components of the JAK/STAT signaling pathway activated by either the pro- or mature forms of BDNF will be identified. We will also determine whether there is a direct association of neurotrophin receptors TrkB and p75NTR with the JAK/STAT complex, as well as the potential role of JAK/STAT activation to epileptogenesis in the pilocarpine TLE model. The proposed studies lay the foundation for directly identifying distinct members of the BDNF- induced JAK/STAT pathway activated by SE, with the promise of providing novel therapeutic targets for future treatment of intractable epilepsy as well as other disorders that display reduced 11 subunit expression. PUBLIC HEALTH RELEVANCE: Epilepsy is a neurological disorder affecting more than 50 million people worldwide (Epilepsy Foundation, 2008). Alterations in neurotransmitter receptor subunits may contribute to seizure susceptibility in one form of epilepsy, temporal lobe epilepsy. The proposed studies will examine the signaling pathway contributing to these changes with the hope of identifying novel targets for more effective treatment of epilepsy.