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

摘要摘要 血管认知障碍(VCI)是仅次于阿尔茨海默病的第二大痴呆症原因。 VCI最常见的原因是脑部小血管疾病(SVD)。奇异值分解背后的机制是 知之甚少，目前还没有专门的治疗方法来预防或治疗SVD和相关的VCI。 我们先前已经发现，酶溶解的环氧化物水解酶(SEH)在 死亡性痴呆患者脑组织微血管内皮细胞的研究 SVD的尸检组织病理学证据。表达人sEH基因的转基因小鼠 内皮Tie2启动子(Tie2-hsEH)表现出年龄依赖性的认知缺陷，支持 内皮细胞sEH上调与认知损害。Seh对14，15起事故负责- 环氧二十碳三烯酸酯(14，15-EET)，一种具有血管扩张剂和血管保护作用的内源性脂质信号分子 优先作用于小血管的特性。我们最近鉴定出G蛋白偶联受体39 (GPR39)作为14，15-EET的分子靶点，定位于人和小鼠脑内毛细血管周细胞。 目前的建议将检验内皮细胞-周细胞EET/GPR39信号起保护作用的假设 通过保护毛细血管血流发挥抗衰老和SVD相关认知损害的作用。为了支持这一点 假设，我们的初步数据显示GPR39基因敲除小鼠(GPR39KO)表现出空间记忆缺陷， 人类的GPR39 SNPs与脑白质高强度体积相关，白质高强度体积是VCI的MRI标志物。在AIM 1，我们将使用3、12和18个月大的雄性和雌性WT和GPR39 KO小鼠来验证这一假设 GPR39在周细胞中上调，以补偿内皮EET的损失，以维持足够的 毛细血管流动和缓解与年龄相关的认知功能衰退。我们将使用无偏见、高通量的脂质组学来 表征脑氧磷脂的年龄相关性变化，并用磷蛋白质组学研究 孤立的周细胞中的下游信号。目标2将确定GPR39在认知障碍中的作用 与慢性脑低灌注(CCH)有关。我们将确定GPR39缺失是否会加剧CCH相关 毛细血管功能障碍和认知障碍，可以通过增加WT的内皮EETs来逆转， 但不是GPR39 KO小鼠。目标3将确定GPR39激动剂是否可以预防认知障碍和 老年小鼠和CCH小鼠的毛细血管功能障碍。拟议的研究具有非常重要的意义和技术意义。 和概念上的创新，因为它们将促进对VCI基础机制的理解，并提出 治疗衰老相关VCI的潜在新疗法。

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.