Proteostasis in the aging and Alzheimer's disease brain: are the ATases novel targets?

项目摘要 由于我们人口的寿命延长，与年龄相关的残疾问题有 变得更加重要。特别是，认知丧失和痴呆症的残疾目前是 在医疗条件中排名第二的昂贵。老龄化也是散发性的最重要的危险因素 阿尔茨海默病(AD)。自噬是细胞降解机制的重要组成部分。这很有帮助 处理细胞内形成的大的有毒蛋白质聚集体。自噬功能的故障导致了 许多与年龄相关的慢性疾病的进展。对衰老和阿尔茨海默病小鼠模型的研究表明 通过刺激自噬来改善蛋白抑制功能可能是有益的。因此，解决年龄问题-和 疾病相关的蛋白平衡功能障碍以及改善正常的蛋白平衡机制是一种 生物医学研究的活跃目标和老龄化研究的关键重点领域。N-ε-赖氨酸乙酰化是一种 必要的翻译后修饰。四十多年来，人们一直认为赖氨酸乙酰化可以 仅见于胞浆和胞核。然而，在2007年，我们报道了短暂的赖氨酸乙酰化 内质网(ER)货物蛋白。随后的研究表明，内质网有两个 乙酰转移酶(ATase1和ATase2)以及转运乙酰基的膜转运蛋白(AT-1)。 心跳过多进入急诊室管腔。在这里，我们报告了内质网管腔中的Nε-赖氨酸乙酰化调节正常 分泌途径的蛋白稳定。始终如一地，通过瞄准ER乙酰化机制，我们能够 挽救AD小鼠模型的表型，但不是亨廷顿病或肌萎缩侧索硬化症。 这些结果是通过使用(在我们实验室产生的)还原乙酰化的小鼠模型获得的 以及以ATase为靶点的生化抑制剂(在我们的实验室中确定)。的一般假设 本研究对ATase1和ATase2的生化和生物学作用进行了功能表征 将帮助我们剖析认知衰退的重要分子方面，认知衰退是衰老和阿尔茨海默病的特征；a 推论认为ATase1和ATase2是改善蛋白平衡功能的有效靶点。 衰老和AD过程中的分泌途径。具体目标1将阐明导致 ATase1和ATase2在衰老和AD过程中的转录调控。具体目标2将确定结构 以及可用于翻译目的的ATase的酶特性(结构生物化学)。 具体目标3将针对ATase1和ATase2的机械下游，以了解它们是如何调节的 自噬的诱导和有毒蛋白质聚集体的处置。一起，目标1-3将剖析 ATase作为年龄和AD神经病理的功能的生物学和生化作用，并将确定 新的结构特异性抑制剂，可改善大脑的蛋白平衡功能。这些目标包括 结构生物化学以及分子和生物物理策略的结合。最后，具体目标4 将使用新开发的小鼠模型和新的ATase特异性抑制剂来确定治疗潜力。

Project Summary Due to the increased lifespan of our population, problems linked to age-associated disabilities are becoming more important. In particular, the disability for cognitive loss and dementia combined is currently the second most expensive among medical conditions. Aging is also the most important risk factor for sporadic Alzheimer's disease (AD). Autophagy is an essential component of the cell degrading machinery. It helps dispose of large toxic protein aggregates that form within the cell. Malfunction of autophagy contributes to the progression of many chronic age-associated diseases. Studies in mouse models of aging and AD suggest that improving proteostatic functions by stimulating autophagy can be beneficial. As such, resolving age- and disease-associated proteostasis dysfunctions as well as improving normal proteostasis mechanisms is an active target for biomedical research and a key focal area for aging research. Nε-lysine acetylation is an essential post-translational modification. For more than forty years it was assumed that lysine acetylation could only occur in the cytosol and nucleus. However, in 2007, we reported the transient lysine acetylation of endoplasmic reticulum (ER) cargo proteins. Subsequent studies revealed that the ER has two acetyltransferases (ATase1 and ATase2) as well as a membrane transporter (AT-1) that translocates acetyl- CoA into the ER lumen. Here, we report that Nε-lysine acetylation in the ER lumen regulates normal proteostasis of the secretory pathway. Consistently, by targeting the ER acetylation machinery, we were able to rescue the phenotype of a mouse model of AD, but not Huntington disease or amyotrophic lateral sclerosis. These results were obtained by using a mouse model of reduced acetylation (generated in our laboratory) as well as biochemical inhibitors that target the ATases (identified in our laboratory). The general hypothesis of this research is that functional characterization of the biochemical and biological roles of ATase1 and ATase2 will help us dissect important molecular aspects of the cognitive decline that characterizes aging and AD; a corollary hypothesis is that ATase1 and ATase2 are valid targets to improve proteostatic functions of the secretory pathway during aging and AD. Specific Aim 1 will elucidate the mechanisms responsible for the transcriptional regulation of ATase1 and ATase2 during aging and AD. Specific Aim 2 will identify structural and enzymatic features (structural biochemistry) of the ATases that can be used for translational purposes. Specific Aim 3 will target the machinery down-stream of ATase1 and ATase2 to understand how they regulate the induction of autophagy and the disposal of toxic protein aggregates. Together, Aims 1-3 will dissect the biological and biochemical roles of the ATases as a function of age and AD neuropathology, and will identify new structure-specific inhibitors to improve proteostatic functions of the brain. These Aims include a combination of structural biochemistry as well as molecular and biophysical strategies. Finally, Specific Aim 4 will use newly developed mouse models and new ATase-specific inhibitors to determine therapeutic potential.