Mechanisms of Angiotensin I Converting Enzyme in Alzheimer's disease

血管紧张素转换酶(ACE1)与肾素血管紧张素系统(RAS)在血管系统中的作用 调节血压(BP)，尽管它们也在大脑的神经元中表达，并可能起到一定的作用 在阿尔茨海默病(AD)中。我们在ACE1中发现了一种罕见的改变蛋白质的变体，R1279Q，它与 家族中有老年痴呆症。为了探讨ACE1R1279Q的致病机制，我们制作了敲击(KI)小鼠。 表达同源小鼠血管紧张素转换酶1突变体。ACE1Ki小鼠大脑ACE1增加，并与年龄相关 神经退行性变、神经炎症、记忆障碍和海马区(髋部)异常脑电，而 其他大脑区域，如小脑，是有抵抗力的，表现出选择性神经退化。这些影响是 由A加速？病理和发生在没有血压变化的情况下。重要的是，ACE1Ki介导的HIP 血管紧张素转换酶抑制物(ACEI)和血管紧张素II受体(AngII)可预防神经退行性变 1种(AT1R)阻滞剂(ARB)药物。ACE1中细胞凋亡和AT1R信号通过磷酸化ERK增加 我的大脑。ACE1在散发性AD脑中也增加，这表明RAS活性升高是一种常见的 AD的功能。我们假设ACE1 R1279Q通过升高的血管紧张素Ⅱ导致AT1R信号的过度激活， 这会导致髋关节等大脑敏感区域中脆弱神经元的神经退化。一个?及其他 “二次打击”可能增强年龄诱导的ACE1/RAS信号的增加以加速选择性 神经退行性变。然而，负责ACE1相关的机制和细胞类型 神经退行性变尚不清楚。在本R01中，我们将测试有关小胶质细胞、微血管 周细胞和神经元中的ACE1介导的神经变性。除了假设检验，我们还将采取 以发现为基础的创新方法。我们将证实在人类阿尔茨海默病大脑中发现的分子变化 老鼠。在目标1中，我们将测定小胶质细胞的单细胞转录本和磷酸蛋白质体。 ACE1Ki小鼠有无A？病理学。此外，我们还将分析AT1R基因在ACE1KI小鼠中的表达 在小胶质细胞中被条件性敲除(CKO)。在目标2中，我们将研究单细胞转录和 ACE1Ki小鼠微血管周细胞的磷酸化蛋白组学研究病理学。我们还将 确定血管紧张素转换酶1基因突变是否损害脑血流并导致血脑屏障渗漏 老鼠。此外，我们将分析ACE1KI小鼠与周细胞特异性AT1R CKO小鼠的杂交。在目标3中，我们 将测定有无ACE1KI小鼠神经元的单细胞转录本和磷酸蛋白质体 一个?无论是否接受ARB氯沙坦治疗，均需进行病理学检查。此外，我们还将分析ACE1 Ki小鼠 与神经元特异性AT1R CKO小鼠杂交。在目标4中，我们将验证在 人AD脑内ACE1Ki小鼠。我们预计R01将提供对ACE1/RAS的机械性见解- 介导的神经退行性变及其与A？病理学，这些知识将对 阿尔茨海默病治疗的发展。

Angiotensin converting enzyme (ACE1) and the renin-angiotensin system (RAS) function in the vascular system to regulate blood pressure (BP), although they are also expressed in neurons of the brain and may have a role in Alzheimer's disease (AD). We discovered a rare protein-altering variant in ACE1, R1279Q, that is associated with AD in families. To investigate the pathogenic mechanism of ACE1 R1279Q, we made knockin (KI) mice that express the cognate murine ACE1 variant. ACE1 KI mice have increased brain ACE1 and have age-related neurodegeneration, neuroinflammation, memory deficits, and abnormal EEG in the hippocampus (HIP), while other brain regions like cerebellum are resistant, demonstrating selective neurodegeneration. These effects are accelerated by A? pathology and occur in the absence of BP changes. Importantly, ACE1 KI-mediated HIP neurodegeneration is prevented by treatment with ACE1 inhibitor (ACEi) and angiotensin II (AngII) receptor type 1 (AT1R) blocker (ARB) drugs. Apoptosis and AT1R signaling via phosphorylated ERK are increased in ACE1 KI brains. ACE1 is also increased in sporadic AD brain, suggesting that elevated RAS activity is a common feature of AD. We hypothesize that ACE1 R1279Q causes over-activation of AT1R signaling via elevated AngII, which leads to neurodegeneration of vulnerable neurons in susceptible brain regions such as HIP. A? and other “second hits” may potentiate the age-induced increase in ACE1/RAS signaling to accelerate selective neurodegeneration. However, the mechanisms and cell types responsible for ACE1-associated neurodegeneration are unclear. In this R01, we will test hypotheses about the roles of microglia, microvessel pericytes, and neurons in ACE1-mediated neurodegeneration. In addition to hypothesis testing, we will take innovative discovery-based approaches. We will confirm in human AD brain molecular changes identified in mouse. In Aim 1, we will determine the single cell transcriptomes and phosphoproteomes of microglial cells of ACE1 KI mice with or without A? pathology. In addition, we will analyze ACE1 KI mice in which the AT1R gene is conditionally knocked out (cKO) in microglia. In Aim 2, we will investigate the single cell transcriptomes and phosphoproteomes of microvessel pericytes of ACE1 KI mice with or without A? pathology. We will also determine if the ACE1 mutation impairs cerebral blood flow and causes blood-brain barrier leakage in ACE1 KI mice. Additionally, we will analyze ACE1 KI mice crossed with pericyte-specific AT1R cKO mice. In Aim 3, we will determine the single cell transcriptomes and phosphoproteomes of neurons of ACE1 KI mice with or without A? pathology and with or without treatment with the ARB losartan. In addition, we will analyze ACE1 KI mice crossed with neuron-specific AT1R cKO mice. In Aim 4, we will validate molecules and pathways identified in ACE1 KI mice in human AD brain. We expect this R01 will provide mechanistic insights into ACE1/RAS- mediated neurodegeneration and its relationship with A? pathology, knowledge that will be highly valuable for the development of AD therapeutics.