Endothelial Cell Epigenetics and Blood-Brain Barrier.

项目摘要/摘要： 一些针对神经元损伤的临床试验未能证明对中风患者有显著好处。 最近的研究表明，中风后功能不良的一个重要因素是血管，尤其是 中风后血脑屏障(BBB)破坏。目前还没有治疗血脑屏障渗漏和恢复活力的治疗方法 中风后的中枢神经系统(CNS)血管。在这里，我们提出两种不同的方法来实现这一目标。 目标1：基因表达模式部分是由表观遗传过程设定的，表观遗传过程将基因组分类为活跃的 并默默支持发展和差异化。几乎对表观遗传机制一无所知 治理BBB发展。这种方法是基于这样一个中心前提，即理解表观遗传学 调节完整血脑屏障形成的机制可以识别调节血脑屏障的新靶点。有趣的是，在 我们的初步实验发现，在发育过程中，一些重要的bbb基因在转录上受到抑制。 在成人中枢神经系统内皮细胞(ECs--血脑屏障的中心)。此外，我们发现两种主要的表观遗传酶 组蛋白去乙酰化2(HDAC2)和多梳抑制复合体2(PRC2)介导了这种转录抑制。基座 根据这些新发现，我们提出，在胚胎大脑发育过程中，表观遗传调节因子HDAC2和HDAC2 PRC2通过转录抑制特定的BBB基因建立完整的BBB。此外，我们假设，虽然这一点 表达谱是维持成人血脑屏障功能所必需的，它也有助于中枢神经系统受损的血脑屏障修复 卒中后的ECS。这项研究将确定表观遗传调节因子HDAC2和PRC2作为新的治疗靶点 在疾病和治疗期间操纵血脑屏障，将促进关于血脑屏障发展的现有知识。 目的2：我们的第二种方法是针对脑血管中的核心信号通路。在早期大脑中 在发育过程中，Wnt/β-Catenin途径协调血脑屏障的发育和中枢神经系统的血管生成。然而，WNT/β- 连环蛋白途径在血管发育后期减少，在成年中枢神经系统内皮细胞中几乎不活跃，使其难以 针对中枢神经系统疾病的血管修复的这一途径。我们新的初步数据证明了表观遗传机制 成人中枢神经系统内皮细胞Wnt通路失活的原因及Wnt通路可在成年中枢神经系统内皮细胞中重新激活 通过表观遗传操作和Wnt配体刺激。因此，我们假设重新激活WNT/β- 成人中枢神经系统内皮细胞的连环蛋白途径将恢复包括血脑屏障形成和血管生成在内的发育表型 在成人中枢神经系统内皮细胞，从而促进中风后血脑屏障修复和血管再生。WNT小路，很长一段时间 由于在成人血管中不存在，所以被认为是不可用药的，我们对靶向血脑屏障的Wnt途径的评估 修复将改变人们的思维方式，导致将这一途径定位于中枢神经系统和其他疾病。 如果成功，这项建议将为开发新的表观遗传学和Wnt靶向铺平道路 修复血脑屏障并改善中风患者预后的治疗。该项目的总体影响很大，因为它 提出了一种广泛适用的策略来修复血脑屏障，血脑屏障是几种中枢神经系统疾病的核心。

PROJECT SUMMARY/ABSTRACT: Several clinical trials targeting neuronal injury have failed to demonstrate significant benefit in stroke patients. Recent studies suggest that there is a significant vascular component to poor functional outcomes after stroke, particularly post-stroke blood-brain barrier (BBB) disruption. Currently no treatments available to treat leaky BBB and rejuvenate central nervous system (CNS) vessels after stroke. Here we propose two different approaches to reach this goal. Aim 1: Gene expression patterns are set, in part, by epigenetic processes that classify the genome into active and silent to support the development and differentiation. Nearly nothing is known about the epigenetic mechanisms that govern the development of BBB. This approach is based on the central premise that understanding the epigenetic mechanisms that regulate the formation of an intact BBB could identify novel targets to modulate BBB. Interestingly, in our preliminary experiment, we found that during development some important BBB genes are transcriptionally repressed in adult CNS endothelial cells (ECs-epicenter of BBB). Further, we discovered that the two major epigenetic enzymes histone deacetylate 2 (HDAC2) and polycomb repressive complex 2 (PRC2) mediate this transcriptional repression. Based on these novel findings, we propose that, during embryonic brain development, the epigenetic regulators HDAC2 and PRC2 establish an intact BBB via transcriptional repression of specific BBB genes. Further, we hypothesize that, while this expression profile is essential for maintaining a functional BBB in adults, it also contributes to impaired BBB repair by CNS ECs following stroke. This study will identify the epigenetic regulators HDAC2 and PRC2 as new therapeutic targets to manipulate BBB during disease and therapy and will advance current knowledge regarding BBB development. Aim 2: Our second approach is to target a core signaling pathway in cerebral vessels. During early brain development, the Wnt/β-catenin pathway orchestrates BBB development and CNS angiogenesis. However, the Wnt/β- catenin pathway diminishes during later vessel development and is almost inactive in adult CNS ECs, making it difficult to target this pathway for vascular repair in CNS diseases. Our new preliminary data demonstrate the epigenetic mechanism behind Wnt pathway inactivation in adult CNS ECs and show that the Wnt pathway can be re-activated in adult CNS ECs by epigenetic manipulation and Wnt ligand stimulation. Consequently, we hypothesize that reactivating the Wnt/β- catenin pathway in adult CNS ECs will restore the developmental phenotypes including BBB formation and angiogenesis in adult CNS ECs, thereby promoting BBB repair and vascular regeneration after stroke. The Wnt pathway, for a long time been said to be undruggable owing to its absence in adult vessels, our evaluations on targeting the Wnt pathway for BBB repair will shift the mindset, leading to targeting this pathway for CNS and other diseases. If successful this proposal will pave the way for the development of novel epigenetic and Wnt-targeting therapies to repair the BBB and improve outcomes in stroke patients. The overall impact of the project is high as it proposes a broadly applicable strategy to repair BBB which is central to several CNS disorders.