Astrocytic WNK-SPAK-NKCC1 Cascade in White Matter Astrogliosis and Injury

白质星形胶质细胞增生和损伤中的星形细胞 WNK-SPAK-NKCC1 级联

• 批准号: 10711392
• 负责人: Mohammad Iqbal Hossain Bhuiyan
• 金额: $ 43.54万
• 依托单位: UNIVERSITY OF TEXAS EL PASO
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-04-15 至 2027-03-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10711392
• 关键词: Astrocytic; WNK; SPAK; NKCC1; Cascade

PROJECT SUMMARY Vascular contributions to cognitive impairment and dementia (VCID) are currently considered as one of the leading causes of dementing illness. The key feature of VCID is diffuse white mater lesions (WML) and hippocampal damage, including myelin loss, axonal disruption, and astrogliosis. However, the underlying molecular and cellular mechanisms for WML, hippocampal damage, and cognitive impairment are not well understood. Hypertension and atherosclerosis are the most significant risk factors for dementia epidemics. Using two mouse models of VCID with chronic bilateral carotid artery stenosis (BCAS), we detected progressive activation of the WNK-SPAK-NKCC1 protein complex in white matter tracts and hippocampus, which is associated with brain lesion and cognitive deficits. Brain Na+-K+-Cl- cotransporter isoform 1 (NKCC1) contributes to intracellular Na+ and Cl- overload, cytotoxic edema, and excitotoxic ischemic neuronal damage. The serine- threonine WNK kinase family [with no lysine (K)], and its downstream kinase SPAK (the STE20/SPS1-related proline/alanine-rich kinase) activate NKCC1 activity via protein phosphorylation. In our pilot study, we detected that BCAS triggered a time-dependent activation of the SPAK-NKCC1 protein complex, specifically in corpus collosum (CC) and hippocampal GFAP+ reactive astrocytes. How the WNK-SPAK-NKCC1 protein complex is stimulated and its role in the pathogenesis of BCAS-induced WML and hippocampal lesion remains unknown. We detected BCAS-induced elevation of interleukin-18 receptor 1 (IL-18R1) expression and nuclear translocation of pNF-κB in GFAP+ reactive astrocytes, which are correlated with increased NF-kB recruitment on the Wnk/Spak/Nkcc1 gene promoters. Importantly, blocking SPAK function with a novel, selective SPAK inhibitor ZT-1a significantly reduced WML, hippocampal CA1 region neurodegeneration, and attenuated cognitive function impairment. Therefore, we propose that activation of the WNK-SPAK-NKCC1 complex plays an important role in the BCAS-induced pathogenesis. We hypothesize that (1) BCAS-induced hypoperfusion stimulates the IL-18/IL-18R-MyD88-NF-κB cascade to upregulate the WNK-SPAK-NKCC1 complex in reactive astrocytes; (2) elevated astrocytic WNK-SPAK-NKCC1 signaling and astrogliosis contribute to cell death of oligodendrocytes (OLs), demyelination, CA1 neuronal loss, and cognitive deficits; and (3) Post-BCAS administration of the novel SPAK kinase inhibitor ZT-1a reduces brain lesions and cognitive deficits by attenuating astrogliosis and degeneration of OLs and CA1 neurons. These hypotheses will be tested in the following specific aims: Aim 1. Identify molecular mechanisms that stimulate WNK-SPAK-NKCC1 cascade activation and astrogliosis in white matter tracts and hippocampus after BCAS. Aim 2. Determine causative roles of BCAS-induced astrocytic WNK-SPAK-NKCC1 cascade activation in brain lesion and cognitive function impairment. Aim 3. Investigate the efficacy of the novel SPAK inhibitor ZT-1a in reducing astrogliosis, brain lesion, and cognitive function impairment in the BCAS mice.

项目概要 血管对认知障碍和痴呆（VCID）的影响目前被认为是导致认知障碍和痴呆的原因之一。 痴呆症的主要原因。 VCID 的主要特征是弥漫性白质病变 (WML) 和 海马损伤，包括髓磷脂缺失、轴突破坏和星形胶质细胞增生。然而，底层 WML、海马损伤和认知障碍的分子和细胞机制尚不清楚 明白了。高血压和动脉粥样硬化是痴呆症流行的最重要的危险因素。使用 在两种患有慢性双侧颈动脉狭窄（BCAS）的 VCID 小鼠模型中，我们检测到进行性进展 白质束和海马中 WNK-SPAK-NKCC1 蛋白复合物的激活， 与脑损伤和认知缺陷有关。脑 Na+-K+-Cl- 协同转运蛋白异构体 1 (NKCC1) 的贡献 细胞内 Na+ 和 Cl- 超载、细胞毒性水肿和兴奋性缺血性神经元损伤。丝氨酸- 苏氨酸 WNK 激酶家族 [不含赖氨酸 (K)] 及其下游激酶 SPAK（STE20/SPS1 相关 富含脯氨酸/丙氨酸激酶）通过蛋白质磷酸化激活 NKCC1 活性。在我们的试点研究中，我们发现 BCAS 触发了 SPAK-NKCC1 蛋白复合物的时间依赖性激活，特别是在语料库中 结肠 (CC) 和海马 GFAP+ 反应性星形胶质细胞。 WNK-SPAK-NKCC1 蛋白复合物是如何形成的 刺激及其在 BCAS 诱导的 WML 和海马病变发病机制中的作用仍不清楚。 我们检测到 BCAS 诱导的白细胞介素 18 受体 1 (IL-18R1) 表达和核 GFAP+ 反应性星形胶质细胞中 pNF-κB 的易位，与 NF-κB 募集增加相关 Wnk/Spak/Nkcc1 基因启动子。重要的是，用新型选择性 SPAK 抑制剂阻断 SPAK 功能 ZT-1a 显着减少 WML、海马 CA1 区神经变性和认知能力减弱 功能障碍。因此，我们认为 WNK-SPAK-NKCC1 复合物的激活起到了 在 BCAS 诱导的发病机制中发挥重要作用。我们假设 (1) BCAS 引起的低灌注 刺激 IL-18/IL-18R-MyD88-NF-κB 级联反应上调 WNK-SPAK-NKCC1 复合物 星形胶质细胞； (2)星形胶质细胞WNK-SPAK-NKCC1信号传导升高和星形胶质细胞增生导致细胞死亡 少突胶质细胞 (OL)、脱髓鞘、CA1 神经元丢失和认知缺陷； (3) BCAS 后 服用新型 SPAK 激酶抑制剂 ZT-1a 可通过以下方式减少脑损伤和认知缺陷： 减轻 OL 和 CA1 神经元的星形胶质细胞增生和变性。这些假设将在 以下具体目标： 目标 1. 确定刺激 WNK-SPAK-NKCC1 级联激活和星形胶质细胞增生的分子机制 BCAS 后的白质束和海马体。 目标 2. 确定 BCAS 诱导的脑中星形胶质细胞 WNK-SPAK-NKCC1 级联激活的因果作用 病变和认知功能障碍。 目标 3. 研究新型 SPAK 抑制剂 ZT-1a 在减少星形胶质细胞增生、脑损伤和 BCAS 小鼠的认知功能障碍。