ATase1 and ATase2, proteostasis, and neurological diseases

我们在2007年发现N-ε-赖氨酸乙酰化发生在内质网(ER)的管腔内。从最初的发现，我们继续发现了整个ER乙酰化机制(一个膜转运体，AT-1/SLC33A1，以及两个乙酰基转移酶，ATase1和ATase2)，并发现了一段新的ER生物学。具体地说，我们发现ER乙酰化机制调节分泌途径中的蛋白平衡以及不同细胞内细胞器和隔室之间的代谢串扰。基于人类的研究发现，由功能丧失的纯合子和杂合子突变或基因复制事件引起的ER乙酰化功能障碍与不同的人类疾病有关，从大脑发育迟缓和过早死亡到周围形式的神经病、自闭症谱系障碍、智能障碍和节段性衰老。模拟这些遗传事件的小鼠模型概括了相关的人类疾病。重要的是，ATase靶向化合物可以恢复内质网的蛋白抑制功能，拯救动物的疾病表型。 总之，我们已经确定了一种新的分子机制，它是维持分泌途径中蛋白平衡的关键，并且可以被用于(I)了解几种相关神经疾病的病理生理学和(Ii)开发适当的翻译方法来解决蛋白平衡缺陷。这项研究的一般假设是ATase1和ATase2作用于细胞内通讯网络的下游，该通讯网络调节内质网和分泌途径的蛋白恒定功能。我们的主要目标是剖析乙酰辅酶A：赖氨酸乙酰转移酶活性背后的分子机制(S)，并了解基于内质网的乙酰化如何调节分泌途径的效率。 目的1验证ATase具有不同功能的假说，并对蛋白平衡和代谢串扰进行差异性调节。目标2将验证这样一个假设，即独特的结构特征允许ATase对乙酰辅酶A内流、钙离子水平和内质网蛋白平衡的扰动做出反应。目的3将验证这样一个假设，即必须通过Amfion/GDAC在高尔基体的管腔中去除ATase添加到内质网管腔中的乙酰基，以确保新生糖蛋白的正确运输和分泌体的质量。 总之，这项建议是基于我们实验室的新发现，并提供了一系列高度机械化的研究，这些研究有可能定义不同神经疾病的研究(和治疗)的新途径。该提案将使用独特的老鼠模型以及高度集成的新颖实验方法。我们相信，在这些研究完成后，我们将为不同的神经疾病定义一条全新的研究途径。

We discovered that Nε-lysine acetylation occurs in the lumen of the endoplasmic reticulum (ER) in 2007. From that initial finding, we went on to discover the entire ER acetylation machinery (one membrane transporter, AT-1/SLC33A1, and two acetyltranferases, ATase1 and ATase2) and uncover a novel piece of ER biology. Specifically, we discovered that the ER acetylation machinery regulates proteostasis within the secretory pathway as well as metabolic crosstalk between different intracellular organelles and compartments. Human-based studies discovered that dysfunctional ER acetylation, as caused by loss-of-function homozygous and heterozygous mutations or gene duplication events, is associated with different human diseases, from developmental delay of the brain and premature death to peripheral forms of neuropathy, autism spectrum disorder, intellectual disability and segmental progeria. Mouse models that mimic these genetic events recapitulate associated human diseases. Importantly, ATase-targeting compounds that restore the proteostatic functions of the ER rescue the disease phenotypes of the animals. In conclusion, we have identified a novel molecular machinery that is key to the maintenance of proteostasis within the secretory pathway, and that can be targeted to (i) understand the pathophysiology of several related neurological diseases and (ii) develop appropriate translational approaches to resolve proteostatic defects. The GENERAL HYPOTHESIS of this research is that ATase1 and ATase2 act downstream of an intracellular communication network that regulates the proteostatic functions of the ER and secretory pathway. Our main goal is to dissect the molecular mechanism(s) underlying the acetyl-CoA:lysine acetyltransferase activity of the ATases and understand how ER-based acetylation regulates the efficiency of the secretory pathway. Aim 1 will test the hypothesis that the ATases have divergent functions and differentially regulate proteostasis and metabolic crosstalk. Aim 2 will test the hypothesis that unique structural features allow the ATases to respond to acetyl-CoA influx, Ca++ levels, and perturbations in ER proteostasis. Aim 3 will test the hypothesis that the acetyl group added in the ER lumen by the ATases must be removed in the lumen of the Golgi apparatus by Amfion/GDAC to ensure correct trafficking of nascent glycoproteins and the quality of the secretome. In conclusion, this proposal is based on novel findings from our laboratory and offers a series of highly mechanistic studies that have the potential to define new avenues of research (and treatment) for different neurological diseases. The proposal will use unique mouse models as well as highly integrated novel experimental approaches. We believe that upon completion of these studies, we will have defined an entirely new avenue of research for different neurological diseases.