Epigenetic Regulation of Kir4.1 and GLT1 in Pathophysiology

描述(申请人提供)：创伤性脑损伤(TBI)每年影响170多万美国人，是美国幼儿死亡和残疾的主要原因。对于患有脑外伤的儿童，目前的治疗方案很大程度上是从对成人的研究中推断出来的，尽管儿童和成人的大脑存在显著差异。因此，这项建议旨在利用儿童疾病的临床相关模型来专门研究儿童损伤。具体地说，我们将专注于星形胶质细胞在儿童脑外伤中的作用，这是一种高度 研究不足的领域。众所周知，脑和脊髓中的星形胶质细胞在损伤的急性和长期反应中发挥着重要作用。与损伤组织相关的星形胶质细胞称为反应性星形胶质细胞，其特征是蛋白质表达发生深刻变化，导致这些细胞的基本性质发生变化。然而，对星形细胞损伤反应的基因调控知之甚少。这项建议试图通过研究星形胶质细胞在损伤后两个基本功能的调节来解决这个问题：缓冲细胞外K+离子和调节细胞外谷氨酸浓度的能力。这两种星形细胞功能在很大程度上是通过内向整流钾通道Kir4.1和星形胶质细胞谷氨酸转运体GLT-1介导的。在成人脊髓和脑中，细胞外间隙K+和谷氨酸的稳态失调导致神经元过度兴奋，突触生理改变和可塑性。此外，这两个蛋白在发育过程中都受到调节，在谷氨酸能突触发生的高峰期，这两个蛋白在人和啮齿动物的出生后早期发育中的表达显著增加，从而确立了这两个蛋白在未成熟脑中的重要作用。这一发育期也与脑外伤风险最高的年龄段相关。尽管这两种蛋白质在大脑功能中很重要，但人们对它们的调控知之甚少。 在发育过程中或对伤害作出反应。使用与临床高度相关的脑损伤模型，本建议旨在特别提出以下问题：1)儿童损伤后，Kir4.1和GLT-1是否持续减少，导致神经元过度兴奋？2)这些蛋白的丢失是表观遗传调控基因转录的直接结果吗？3)在儿童损伤模型中，使用FDA批准的药物操纵DNA甲基化能否逆转Kir4.1和GLT-1的丢失？这一建议旨在加深我们对星形胶质细胞在儿童创伤性脑损伤和损伤后脑发育异常的病理生理学中的作用的理解。星形胶质细胞是中枢神经系统中含量最丰富的细胞。这些实验的结果可能导致使用FDA批准的药物治疗儿童脑损伤的新治疗策略。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) affects over 1.7 million Americans each year and is the leading cause of death and disability in young children in the United States. For children with TBI, current treatment options are largely extrapolated from studies on adults, despite significant differences between pediatric and adult brains. Therefore, this proposal aims to specifically study pediatric injury, using clinically-relevant models of childhood disease. Specifically, we will focus on the role of astrocytes in pediatric TBI, a highly understudied area of research. It is well established that astrocytes in the brain and spinal cord play a major role in both acute and long term response to injury. Astrocytes associated with injured tissue, termed reactive astrocytes, are characterized by profound changes in protein expression leading to changes in the fundamental properties of these cells. Yet, little is known about the genetic regulation of the astrocytic injury response. This proposal seeks to address this question by examining the regulation of two essential functions of astrocytes following injury: the ability to buffer extracellular K+ ions and to regulate extracellular glutamate concentrations. These two astrocytic functions are largely mediated via the inwardly-rectifying potassium channel, Kir4.1, and the astrocytic glutamate transporter, GLT-1. In the adult spinal cord and brain, dysregulated K+ and glutamate homeostasis in the extracellular space leads to neuronal hyperexcitability, changes in synaptic physiology, and plasticity. Furthermore, both proteins are developmentally regulated with the most significant increases in expression in humans and rodents during early postnatal development at the peak of glutamatergic synaptogenesis, establishing an important role for these two proteins in the immature brain. This developmental period also correlates with the age group highest at risk for TBI. Despite the importance of these two proteins in brain function, very little is known regarding their regulation during development or in response to injury. Using a highly clinical relevant model of TBI, this proposal aims to specifically ask the following questions: 1) Following pediatric injury, is there persistent decrease in Kir4.1 and GLT-1, leading to neuronal hyperexcitability? 2) Is loss of these proteins a direct result of epigenetic modulation of gene transcription? 3) Can manipulation of DNA methylation using FDA-approved drugs reverse the loss of Kir4.1 and GLT-1 in pediatric injury models? This proposal seeks to enhance our understanding of the role of astrocytes, the most abundant cells in the CNS, in the pathophysiology of pediatric traumatic brain injury and abnormal brain development following injury. Results from these experiments could lead to novel therapeutic strategies using FDA-approved drugs for the treatment of TBI in pediatric patients.