PICALM: Role in the pathogenesis and treatment of Alzheimer vascular blood-brain barrier clearance dysfunction, neuronal dysfunction, and amyloid-beta, tau and neurodegenerative disorders

PICALM是晚发性阿尔茨海默病(LOAD)最重要的易感因素之一。它在这方面的作用 然而，疾病的发病机制仍然难以捉摸。我们也没有有效的基于PICALM的治疗方法 广告。PICALM控制细胞受体的内化，以及不同蛋白质在细胞内的运输。PICALM 在脑内皮细胞和神经元中大量表达，但在负荷和一些PICALM SNPs中表达减少。 为了了解PICALM如何调节血管和神经元功能以及AD病理，我们开发了新的 具有PICALM特异性内皮和神经元缺失的小鼠模型。建议进行的研究包括 我们的试点数据表明：i)PICALM控制血液中淀粉样蛋白β(Aβ)和tau的清除- 脑屏障(BBB)和引导其跨内皮BBB跨细胞转运，以及PICALM内皮缺陷 导致Aβ和tau脑积聚；ii)神经元PICALM丢失导致神经元丢失，并呈现 由于N-甲基-D-天冬氨酸受体(NMDAR)的过度表达，它们容易受到兴奋性毒性损伤，以及 Picalm与调节的葡萄糖结合和隔离减少导致的Aβ和tau毒性增加 胞浆中的蛋白78(GRP78)。这反过来又将游离的GRP78穿梭到内质网(ER)受阻 未折叠蛋白反应(UPR)加剧内质网对Aβ和tau的应激反应。自PICALM缺乏以来 导致功能丧失，我们建议测试青蒿琥酯的治疗方法，以增加PICALM，青蒿琥酯是我们的一种先导药物 试点FDA批准的文库筛选，并与基因治疗。我们还生成了一个新的Picalm465R行，其中包含一个 罕见的465R PICALM错义突变，不改变PICALM的表达，但增加其与 GRP78表达于神经元，LRP1表达于内皮细胞。根据我们的试验数据，我们假设PICALM内皮细胞 缺乏会导致Aβ和tau脑积聚，因为它们在血脑屏障的清除功能受损而导致丢失 Picalm引导的A-β和LRP1结合及其与Rab5和Rab11相互作用的研究 Tau BBB转胞作用；而PICALM神经元缺陷将使神经元对兴奋性毒性损伤敏感 由于NMDAR的过度表达，并将通过增加GRP78易位而增加Aβ和tau神经元的毒性 从胞浆到内质网，这将阻碍UPR并增强内质网对Aβ和tau的应激反应。治疗方法 与LRP1和GRP78结合增强的465R突变体将增加Aβ和tau Bbb 清除和保护神经元。我们将研究内皮特异性(AIM1)和神经元特异性 (目的2)PICALM缺乏对血管和神经功能及AD病理的影响；青蒿琥酯的影响 和AAV-PHP.B-PICALM基因治疗(AIM 3)和H465R PICALM突变(AIM 4)。 神经功能与AD病理。我们接下来将确定Aβ和tau BBB跨细胞和 用血脑屏障模型和人rs3851179 PICALM变异体的神经元研究PICALM调节的神经元毒性 和Picalm465R小鼠(AIM 5)。如果成功，这项提议将对PICALM生物学产生独特的新见解 这对于更好地理解PICALM在AD的发病机制和治疗中的作用具有重要意义。

PICALM is one of the most significant susceptibility factors for late onset Alzheimer’s disease (LOAD). Its role in disease pathogenesis, however, remains elusive. We also do not have an effective PICALM-based therapy for AD. PICALM controls internalization of cell receptors, and intracellular trafficking of different proteins. PICALM is abundantly expressed in brain endothelium and neurons, but is reduced in LOAD and by some PICALM SNPs. To understand how PICALM regulates vascular and neuronal function and AD pathology, we developed new mouse models with PICALM-specific deletion from endothelium and neurons. The proposed studies are supported by our pilot data showing: i) that PICALM controls amyloid-β (Aβ) and tau clearance across the blood- brain barrier (BBB) and guides their trans-endothelial BBB transcytosis, and that PICALM endothelial deficiency leads to Aβ and tau brain accumulation; and ii) that PICALM loss from neurons leads to neuron loss, and renders them susceptible to both excitotoxic injury due to N-methyl-D-aspartate receptors (NMDAR) overexpression, and elevated Aβ and tau toxicity resulting from diminished PICALM binding to, and sequestration of glucose regulated protein 78 (GRP78) in the cytosol. This in turn shuttles free GRP78 to endoplasmic reticulum (ER) hampering unfolded protein response (UPR) which aggravates ER stress response to Aβ and tau. Since PICALM deficiency leads to loss-of-function, we propose to test therapies to increase PICALM with artesunate, a lead drug from our pilot FDA-approved library screen, and with gene therapy. We also generated a new Picalm465R line carrying a rare 465R PICALM missense mutation that does not alter PICALM expression, but increases its binding to GRP78 in neurons and LRP1 in endothelium. Based on our pilot data, we hypothesize that PICALM endothelial deficiency will lead to Aβ and tau brain accumulation due to their impaired clearance at the BBB caused by loss of PICALM binding to LRP1 and its deficient interactions with Rab5 and Rab11 during PICALM-guided Aβ and tau BBB transcytosis; whereas PICALM neuronal deficiency will render neurons susceptible to excitotoxic injury due to NMDAR overexpression, and will increase Aβ and tau neuronal toxicity by increasing GRP78 translocation from the cytosol to ER that will hamper UPR and augment ER stress response to Aβ and tau. Therapies to increase PICALM, and 465R mutant with enhanced binding to LRP1 and GRP78, will increase Aβ and tau BBB clearance and protect neurons. We will study the effects of endothelium-specific (AIM 1) and neuron-specific (AIM 2) PICALM deficiency on vascular and neuronal function and AD pathology; and the effects of artesunate and AAV-PHP.B-Picalm gene therapy (AIM 3), and the H465R PICALM mutation (AIM 4) on vascular and neuronal function and AD pathology. We will next identify molecular steps in Aβ and tau BBB transcytosis and neuronal toxicity regulated by PICALM using BBB models and neurons from human rs3851179 PICALM variants and Picalm465R mice (AIM 5). If successful, this proposal will generate unique new insights into PICALM biology with implications for better understanding of the role of PICALM in the pathogenesis and treatment of AD.