Role of GPR39 in Aging-Related Vascular Cognitive Impairment (VCI)

摘要 血管性认知障碍（VCI）是继阿尔茨海默病之后的第二大常见痴呆原因。 VCI最常见的原因是脑小血管病（SVD）。SVD的潜在机制是 目前尚不清楚，没有特定的治疗方法可用于预防或治疗SVD和相关的VCI。 我们先前已经发现，可溶性环氧化物水解酶（sEH）在大肠杆菌中的表达和活性增加。 来自死亡前痴呆患者的人脑组织的微血管内皮， SVD的死后组织病理学证据。人sEH基因转基因小鼠的研究 内皮Tie 2启动子（Tie 2-hsEH）表现出年龄依赖性认知缺陷，支持了 内皮sEH上调和认知障碍。sEH负责14，15- 环氧二十碳三烯酸（14，15-EET），一种内源性脂质信号分子，具有血管扩张和血管保护作用 这些特性优先作用于小血管。我们最近发现G蛋白偶联受体39 GPR 39作为14，15-EET的分子靶标定位在人和小鼠脑中的毛细血管周细胞中。 目前的建议将测试内皮-周细胞EET/GPR 39信号传导在内皮细胞中起保护作用的假设。 通过保护毛细血管血流，对衰老和SVD相关的认知障碍发挥作用。为支持这一 假设，我们的初步数据显示GPR 39敲除小鼠（GPR 39 KO）表现出空间记忆缺陷， 人类的GPR 39单核苷酸多态性与白色高信号体积相关，这是VCI的MRI标志物。在Aim中 1，我们将使用3、12和18月龄的雄性和雌性WT和GPR 39 KO小鼠来检验假设 GPR 39在周细胞中上调，以补偿内皮细胞的损失，从而维持足够的 毛细血管流动和减轻与年龄相关的认知能力下降。我们将使用无偏的高通量脂质组学， 表征脑氧化脂质的年龄依赖性变化，以及磷酸蛋白质组学研究脑氧化脂质的变化。 在孤立的周细胞下游信号。目的2将确定GPR 39在认知障碍中的作用 慢性脑灌注不足（CCH）。我们将确定GPR 39缺失是否会加重CCH相关性 毛细血管功能障碍和认知功能障碍，可通过增加WT中的内皮细胞凋亡逆转， 而不是GPR 39 KO小鼠。目标3将确定GPR 39激动剂是否可以保护认知障碍， 老年小鼠和CCH小鼠的毛细血管功能障碍。拟议的研究在技术上和意义上都非常重要。 和概念上的创新，因为他们将推进对VCI机制的理解，并提出一个 潜在的治疗衰老相关VCI的新方法。

Summary Abstract Vascular cognitive impairment (VCI) is the second most common cause of dementia after Alzheimer's disease. The most common cause of VCI is cerebral small vessel disease (SVD). The mechanisms underlying SVD are poorly understood, with no specific treatments currently available to prevent or treat SVD and associated VCI. We have previously found increased expression and activity of the enzyme soluble epoxide hydrolase (sEH) in microvascular endothelium of human brain tissue from deceased patients with pre-mortem dementia and postmortem histopathological evidence of SVD. Transgenic mice expressing the human sEH gene under the endothelial Tie2 promoter (Tie2-hsEH) exhibit age-dependent cognitive deficit, supporting a causal link between endothelial sEH upregulation and cognitive impairment. sEH is responsible for the breakdown of 14,15- epoxyeicosatrienoate (14,15-EET), an endogenous lipid signaling molecule with vasodilator and vasoprotective properties that preferentially acts on small blood vessels. We recently identified G protein-coupled receptor 39 (GPR39) as a molecular target for 14,15-EET localized in human and mouse brains in peri-capillary pericytes. The current proposal will test the hypothesis that endothelial-pericyte EET/GPR39 signaling plays a protective role against aging- and SVD-related cognitive impairment by preserving capillary blood flow. In support of this hypothesis, our preliminary data shows that GPR39 knockout mice (GPR39KO) exhibit spatial memory deficit, and GPR39 SNPs in humans correlate with white matter hyperintensity volume, an MRI marker of VCI. In Aim 1, we will use male and female WT and GPR39 KO mice at 3, 12 and 18 months of age to test the hypothesis that GPR39 is upregulated in pericytes to compensate for loss of endothelial EETs in order to maintain adequate capillary flow and mitigate age-related cognitive decline. We will use unbiased, high-throughput lipidomics to characterize age-dependent changes in brain oxylipins, and phosphoproteomics to investigate changes in downstream signaling in isolated pericytes. Aim 2 will determine the role of GPR39 in cognitive impairment related to chronic cerebral hypoperfusion (CCH). We will determine if GPR39 deletion exacerbates CCH-related capillary dysfunction and cognitive impairment, which can be reversed by increasing endothelial EETs in WT, but not GPR39 KO mice. Aim 3 will determine if a GPR39 agonist can protect against cognitive impairment and capillary dysfunction in aged mice and mice with CCH. The proposed studies are highly significant and technically and conceptually innovative, as they will advance understanding of mechanisms underlying VCI, and propose a potential novel therapy for aging-related VCI.