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

• 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
• 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

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.

项目摘要 脑血管相关的星形胶质细胞末端在地层和 维持血脑屏障（BBB），并调节神经血管耦合和 脑血流（CBF）。缺血性中风会引起结构和生化变化 血管周围星形胶质细胞，但基本的分子机制以及随后对 脑容器损伤/维修尚不清楚。以前，我们证明了这一点 缺血和缺氧，反应性星形胶质细胞刺激Na+/H+交换器同工型1蛋白（NHE1） 活性以抵消酸性PHI。这会导致细胞内Na+超负荷，星形细胞shwelling， 谷氨酸摄取受损，这加剧了缺血性脑损伤。我们最近的研究 表明在星形胶质细胞（Astro-ko）中选择性删除了缺血性中风 - 介导的星形胶质细胞增多症，保留的BBB功能以及降低的大脑容器损伤 局灶性缺血性中风的小鼠模型（瞬时脑动脉闭塞）。尽管有 星形细胞NHE1缺失在缺血性大脑中赋予的神经保护作用，精度 该过程中涉及的分子机制尚不完全了解。我们的初步 研究表明，Wnt信号通路基因是最显着上调的基因 NHE1 Astro-Ko缺血大脑。最重要的是，Astro-KO小鼠中NHE1的目标删除 引起Wnt 7a/b和-catenin蛋白的升高，伴随着 紧密连接蛋白（TJ）和缺血后血管中TJ结构的保存 中风。这些新发现使我们假设删除星形胶质细胞NHE1会促进 Wnt/-catenin介导的信号传导机制通过缺血组织修复。我们将调查 这增加了NHE1 Astro-KO小鼠中的Wnt7a/B基因表达，导致1）增加 血管内皮细胞中的Wnt/-catenin信号传导，2）改善BBB结构和 功能完整性和3）通过血管生成和恢复促进血管恢复 缺血性中风后脑流量调节。完成三个特定目标的完成将产生 新知识并确定新的热热剂，以促进血管维修 缺血性中风。