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: 10529322
• 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/10529322
• 关键词: Acceleration; Area; Astrocytes; Biochemical; Biochemical Process; Blood - brain barrier anatomy; Blood Preservation; Blood Vessels; Brain; Brain Hypoxia-Ischemia; Brain Ischemia; C57BL/6 Mouse; Cell Proliferation; Cerebrovascular Circulation; Cerebrum; Endothelial Cells; Endothelium; Gene Expression; Genes; Genetic Transcription; Genotype; Glial Fibrillary Acidic Protein; Glutamates; Goals; 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; 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; improved; insight; mRNA Expression; mouse model; neurological recovery; neuroprotection; neurovascular coupling; neurovascular injury; novel; novel therapeutics; pharmacologic; 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 脑血流量（CBF）。缺血性中风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 脑血管损伤/修复尚不清楚。之前，我们表明，为了响应 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，从而加剧缺血性脑损伤。我们最近的研究 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（短暂性大脑中动脉闭塞）小鼠模型。尽管 缺血性大脑中星形胶质细胞 Nhe1 缺失所赋予的神经保护作用，精确的 该过程涉及的分子机制尚不完全清楚。我们的初步 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，Astro-KO 小鼠中 Nhe1 的靶向缺失 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 中风。这些新发现使我们推测星形胶质细胞 Nhe1 的缺失会促进 通过 Wnt/−连环蛋白介导的信号机制修复缺血组织。我们将调查 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。完成三个具体目标将产生 新知识并确定促进血管修复的新治疗药物 缺血性中风。