Mechanisms of Impaired Lysosomal Biogenesis and Autophagy in Alcohol-Associated Alzheimer's Disease

摘要 酗酒会损害肝脏、胰腺、心脏、大脑和肌肉。酗酒的一个严重后果是 认知障碍和痴呆。虽然酒精在促进阿尔茨海默病（AD）中的作用是 怀疑，基本机制知之甚少。AD的一个潜在机制是 自噬受损或不足，这是一种进化上保守的溶酶体降解途径， 细胞器和蛋白质稳态。自噬通常随着年龄的增长而下降，导致细胞内 包括tau和β淀粉样蛋白在内的错误折叠蛋白以及受损的线粒体。我们最近的工作 研究表明，酒精诱导转录因子EB（TFEB）功能障碍，TFEB是一种主要的调节因子， 溶酶体生物发生TFEB受损导致溶酶体生物发生和线粒体自噬减少， 酒精性肝炎和胰腺炎。除了调节自噬，我们还证明了TFEB 通过上调过氧化物酶体增殖物激活受体γ增加线粒体生物合成 辅激活因子1-α（PGC 1-α）。更重要的是，降低的细胞核TFEB水平与人类免疫相关。 酒精性肝炎和胰腺炎，但其在酒精相关AD中的作用尚未研究。我们 初步结果表明，酒精降低总TFEB和核TFEB，但增加泛素化蛋白 在小鼠体内。此外，老年小鼠（22个月大）也具有减少的核TFEB染色，但 与年轻小鼠（3个月大）相比，增加的p62和磷酸化的Tau。这些 集体观察表明，酒精消费和衰老可能协同作用，扰乱 TFEB-溶酶体生物发生轴，从而导致受损的脑自噬。在这里，我们假设慢性 酒精消耗复合了脑中TFEB介导的溶酶体生物发生的年龄相关性降低， 这又导致受损线粒体和蛋白质聚集体的积累。这些现象 发生在AD中，我们提出的实验有望建立大脑衰老，酒精和 消耗和AD病理学。我们进一步预测TFEB的过表达和TFEB敲入转基因 小鼠将防止这些脑老化和酒精诱导的病理。我们还建议评估 从高通量筛选中鉴定的新型TFEB激动剂的潜在神经保护作用， 最近完成的。拟议工作的顺利完成将为以下方面提供一个新的范例： 揭示TFEB在酒精相关AD和脑老化中自噬和溶酶体生物学中的作用。

Abstract Alcohol abuse damages liver, pancreas, heart, brain, and muscle. One severe outcome of alcohol abuse is cognitive impairment and dementia. Although a role for alcohol in promoting Alzheimer's disease (AD) is suspected, the underlying mechanisms are poorly understood. One proposed underlying mechanism in AD is impaired or insufficient autophagy, an evolutionarily conserved lysosomal degradation pathway that regulates organelle and protein homeostasis. Autophagy generally declines with age, resulting in an accumulation of misfolded proteins including tau and β amyloid, as well as damaged mitochondria. Our recent work has demonstrated that alcohol induces dysfunction of transcription factor EB (TFEB), a master regulator of lysosomal biogenesis. Impaired TFEB leads to decreased lysosomal biogenesis and mitophagy resulting in alcoholic hepatitis and pancreatitis. In addition to regulating autophagy, we also demonstrated that TFEB increased mitochondrial biogenesis by up-regulating peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC1-α). More importantly, decreased nuclear TFEB levels is associated with human alcoholic hepatitis and pancreatitis but its role in alcohol-associated AD has not been investigated. Our preliminary results showed that alcohol decreased total and nuclear TFEB but increased ubiquitinated proteins in mouse hippocampi. In addition, aged mice (22-months old) also have decreased nuclear TFEB staining but increased p62 and phosphorylated Tau in the hippocampi compared with young mice (3-months old). These collective observations suggest that alcohol consumption and aging may synergistically interact to perturb the TFEB-lysosome biogenesis axis, thereby leading to impaired brain autophagy. Here, we hypothesize chronic alcohol consumption compounds age-related decrease of TFEB-mediated lysosomal biogenesis in the brain, which in turn leads to an accumulation of damaged mitochondria and protein aggregates. These phenomena occur in AD, and our proposed experiments promise to establish links between brain aging, alcohol consumption, and AD pathology. We further predict overexpression of TFEB and TFEB knockin transgenic mice will protect against these brain aging and alcohol-induced pathologies. We also propose to assess potential neuroprotective effects of novel TFEB agonists identified from a high-throughput screening that were recently completed. The successful completion of the proposed work will provide a new paradigm of uncovering the role of TFEB in autophagy and lysosome biology in alcohol-associated AD and brain aging.