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

项目摘要 由于我国人口寿命的延长，与年龄有关的残疾问题日益严重。 变得更加重要。特别是，认知丧失和痴呆综合残疾目前是 在医疗条件中排名第二。老龄化也是最重要的危险因素， 阿尔茨海默病（AD）。自噬是细胞降解机制的重要组成部分。它有助于 处理细胞内形成的大的有毒蛋白质聚集体。自噬功能障碍导致 许多慢性年龄相关疾病的进展。对衰老和AD小鼠模型的研究表明， 通过刺激自噬来改善蛋白质抑制功能是有益的。因此，解决年龄-和 疾病相关的蛋白质稳态功能障碍以及改善正常的蛋白质稳态机制是一种 生物医学研究的活跃目标和老龄化研究的关键重点领域。Nε-赖氨酸乙酰化反应是一种 重要的翻译后修饰。四十多年来，人们一直认为赖氨酸乙酰化可以 只发生在细胞质和细胞核中。然而，在2007年，我们报道了 内质网（ER）货物蛋白。随后的研究表明，ER有两个 乙酰转移酶（AT酶1和AT酶2）以及转运乙酰- CoA进入ER管腔。在这里，我们报告说，在ER腔Nε-赖氨酸乙酰化调节正常 分泌途径的蛋白质稳态。一致地，通过靶向ER乙酰化机制，我们能够 挽救AD小鼠模型的表型，但不能挽救亨廷顿病或肌萎缩侧索硬化症。 这些结果是通过使用乙酰化减少的小鼠模型（在我们的实验室中产生）获得的， 以及靶向AT酶的生化抑制剂（在我们的实验室中鉴定）。的一般假设 本研究是对ATase 1和ATase 2的生化和生物学作用的功能表征， 将帮助我们剖析认知能力下降的重要分子方面，这是衰老和AD的特征; 一个必然的假设是，ATase 1和ATase 2是有效的目标，以改善蛋白质的功能， 分泌途径在衰老和AD。具体目标1将阐明负责 ATase 1和ATase 2在衰老和AD中的转录调控。具体目标2将确定结构 和可用于翻译目的的AT酶的酶特征（结构生物化学）。 具体目标3将针对ATase 1和ATase 2的下游机制，以了解它们如何调节 自噬的诱导和有毒蛋白质聚集体的处理。目标1-3将一起剖析 AT酶作为年龄和AD神经病理学的函数的生物学和生物化学作用，并将鉴定 新的结构特异性抑制剂，以改善大脑的蛋白质稳定功能。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。具体目标4 将使用新开发的小鼠模型和新的AT酶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.