Mucolipin-1-Mediated Mechanisms of Neuronal Clearance in Alzheimer’s Disease

最近，内溶酶体系统的抑制被描述为最早的变化之一 阿尔茨海默病(AD)的大脑，并可能导致众所周知的特征：形成和积聚 淀粉样蛋白和Tau缠结。我们最近发表的研究表明，在早发性家族性阿尔茨海默病和晚发性AD中 散发性AD核转录因子EB(TFEB)的活性，从而导致许多细胞 清除机制大大减弱。我们在这项建议中提出的初步研究确定了 TFEB-靶基因Mucolipin(MCOLN1)作为内溶酶体转运和清除的中央调节因子 AD人类大脑，培养的人类神经元，以及疾病的小鼠模型。MCOLN1是内溶酶体 钙释放通道在调节TFEB信号、细胞器融合、 胞吐和贩卖。我们发现携带APP、BACE1和Aβ的内溶酶体含有低水平的 MCOLN1，不能与Dynein结合，并在死后的人脑和 培养AD患者的神经细胞。我们观察到MCOLN1的重新激活或过表达 人AD神经元和5xFAD小鼠促进Aβ阳性细胞的逆行转运和清除 因此，来自突触前终末的内溶酶体和来自细胞外间隙的纤维状Aβ 从而改善记忆功能。我们将测试MCOLN1驱动的总体假设 内溶酶体转运以维持神经清除及其对已知阿尔茨海默氏症的放松调节结果 疾病特征包括β沉积和记忆力丧失。我们的分子传感器、工具、人类神经元 这些品系和转基因小鼠将被用来检验MCOLN1驱动内溶酶体的总体假设 维持神经清除的贩运及其放松管制导致已知的阿尔茨海默病的特征 包括失忆。 这项建议的总体目标是1)了解导致抑制AD的特定机制 内体运输和自噬，以及2)确定神经元功能衰竭的后果 阿尔茨海默病的清除，可以促进未来的干预措施的发展，以保持神经元的动态平衡 衰老。

Recently, inhibition of the endolysosomal system has been described among the earliest changes in Alzheimer’s disease (AD) brains and may contribute to the well-known hallmarks: formation and buildup of amyloid and Tau tangles. Our recently published studies show that in early onset familial AD and late onset sporadic AD nuclear activity of the transcription factor EB (TFEB) and consequently many of the cellular clearance mechanisms are greatly attenuated. Our preliminary studies presented in this proposal identify the TFEB-target gene, Mucolipin (MCOLN1), as the central regulator of endolysosomal trafficking and clearance in AD human brains, cultured human neurons, and a mouse model of the disease. MCOLN1 are endolysosomal calcium release channels playing central roles in the regulation of the TFEB signaling, organelle fusion, exocytosis, and trafficking. We find that endolysosomes carrying APP, BACE1 and Aβ contain low levels of MCOLN1, fail to tether to Dynein, and accumulate in neuronal projections in postmortem human brains and cultured neurons from AD patients. We observe that reactivation or overexpression of MCOLN1 in cultured human AD neurons and 5xFAD mice promotes retrograde trafficking and clearance of Aβ-positive endolysosomes from the presynaptic terminals and fibrillary Aβ from the extracellular space, consequently leading to an improvement of memory function. We will test the overall hypothesis that MCOLN1 drives endolysosomal trafficking to maintain neural clearance and its deregulation results in the known Alzheimer’s disease hallmarks including Aβ deposition and memory loss. Our molecular sensors, tools, human neuronal lines and transgenic mice will be used to test the overall hypothesis that MCOLN1 drives endolysosomal trafficking to maintain neural clearance and its deregulation results in the known Alzheimer’s disease hallmarks including memory loss. The overall goal of this proposal is 1) to understand the AD-specific mechanism leading to inhibition of endosomal trafficking and autophagy, and 2) to identify consequences of functional failure of neuronal clearance in AD that could facilitate future development of interventions to preserve neuronal homeostasis in aging.