Astrocytes-Mediated Regulation of Wnt/b-Catenin Pathway in Ischemic Brain

星形胶质细胞介导的缺血脑中 Wnt/b-Catenin 通路的调节

基本信息

批准号：
9885234
负责人：
Gulnaz Begum
金额：
$ 34.23万
依托单位：
UNIVERSITY OF PITTSBURGH AT PITTSBURGH
依托单位国家：
美国
项目类别：
财政年份：
2019
资助国家：
美国
起止时间：
2019-12-01 至 2024-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9885234
关键词：
Area Astrocytes Biochemical Biochemical Process Blood - brain barrier anatomy Blood Preservation Blood Vessels Brain C57BL/6 Mouse Cell Proliferation Cerebrovascular Circulation Cerebrum Endothelial Cells Endothelium Gene Expression Genes Genetic Transcription Genotype Glial Fibrillary Acidic Protein Glutamates Goals Hypoxia Impairment Infarction Ischemia Ischemic Brain Injury Ischemic Stroke Knockout Mice Knowledge Laser Speckle Imaging Ligands Maintenance Mediating Messenger RNA Middle Cerebral Artery Occlusion Molecular Mus Neurologic Deficit Pathologic Pathway interactions Permeability Pharmacology Play Process Protein Isoforms Proteins Protons Recovery Regulation Reporter Research Role Signal Pathway Signal Transduction Signaling Protein Sodium Structure Swelling Testing Therapeutic Agents Tight Junctions Up-Regulation Vascular Endothelial Cell WNT Signaling Pathway Wild Type Mouse angiogenesis astrogliosis beta catenin blood-brain barrier function brain endothelial cell cerebral microvasculature design foot improved insight mRNA Expression mouse model neurological recovery neurovascular coupling neurovascular injury novel novel therapeutics post stroke preservation protein structure receptor repaired response restoration stroke therapy tissue repair transcriptome transcriptome sequencing transcytosis uptake

项目摘要

PROJECT SUMMARY Cerebral vessel-associated astrocyte end-feet play an important role in formation and maintenance of the blood-brain barrier (BBB), and regulation of neurovascular coupling and cerebral blood flow (CBF). Ischemic stroke causes structural and biochemical changes of the perivascular astrocytes, but the underlying molecular mechanisms and subsequent impact on cerebral vessel damage/repair are not well understood. Previously, we show that in response to ischemia and hypoxia, reactive astrocytes stimulate Na+/H+ exchanger isoform 1 protein (NHE1) activity to counteract the acidic pHi. This leads to intracellular Na+ overload, astrocytic swelling, and impaired glutamate uptake, which aggravates ischemic brain damage. Our recent study shows that selective deletion of Nhe1 in astrocytes (Astro-KO) abolished ischemic stroke- mediated astrogliosis, preserved BBB function, and reduced cerebral vessel damage in a mouse model of focal ischemic stroke (transient middle cerebral artery occlusion). Despite the neuroprotective effects conferred by astrocytic Nhe1 deletion in ischemic brains, the precise molecular mechanisms involved in the process are not completely understood. Our preliminary study reveals that Wnt signaling pathway genes are the most significantly upregulated genes in Nhe1 Astro-KO ischemic brains. Most importantly, targeted deletion of Nhe1 in Astro-KO mice caused elevation of Wnt 7a/b and −catenin protein, accompanied with increased expression of tight junction protein (TJ) and preservation of TJ structures in the blood vessels after ischemic stroke. These new findings led us to hypothesize that deletion of astrocytic Nhe1 promotes ischemic tissue repair by Wnt/−catenin mediated signaling mechanisms. We will investigate that increased Wnt7a/b gene expression in Nhe1 Astro-KO mice leads to 1) increased Wnt/−catenin signaling in vascular endothelial cells, 2) improves the BBB structural and functional integrity, and 3) promotes vascular recovery by angiogenesis and restore of the cerebral flow regulation after ischemic stroke. Completion of three specific aims will generate new knowledge and identify novel therapeutic agents for promoting vascular repairs after ischemic stroke.

项目概要脑血管相关星形胶质细胞端足在形成和维持血脑屏障（BBB），调节神经血管耦合和脑血流（CBF）会导致脑组织的结构和生化变化。血管周围星形胶质细胞，但潜在的分子机制及其随后的影响此前，我们对脑血管损伤/修复的了解还不够。缺血缺氧时，反应性星形胶质细胞刺激 Na+/H+ 交换异构体 1 蛋白 (NHE1) 对抗酸性 pHi 的活性，这会导致细胞内 Na+ 超载、星形胶质细胞肿胀，谷氨酸吸收受损，这会加剧缺血性脑损伤。表明选择性删除星形胶质细胞中的 Nhe1 (Astro-KO) 可消除缺血性中风介导星形胶质细胞增生，保留 BBB 功能，并减少脑血管损伤局灶性缺血性中风（短暂的大脑中动脉闭塞）小鼠模型。缺血性脑中星形胶质细胞 Nhe1 缺失所赋予的神经保护作用，精确的我们初步了解该过程涉及的分子机制。研究表明Wnt信号通路基因是上调最显着的基因 Nhe1 Astro-KO 缺血性大脑最重要的是，在 Astro-KO 小鼠中定向删除 Nhe1。引起 Wnt 7a/b 和 β−catenin 蛋白升高，并伴随紧密连接蛋白（TJ）和缺血后血管中 TJ 结构的保存这些新发现使我们发现星形胶质细胞 Nhe1 的缺失会促进中风。我们将研究 Wnt/−连环蛋白介导的信号传导机制修复缺血组织。 Nhe1 Astro-KO 小鼠中 Wnt7a/b 基因表达的增加导致 1) 增加血管内皮细胞中的 Wnt/−连环蛋白信号传导，2) 改善 BBB 结构和功能完整性，3) 通过血管生成和恢复来促进血管恢复缺血性中风后的脑血流调节将产生三个特定目标。新知识并确定促进血管修复的新治疗药物缺血性中风。