Amino-terminal acetylation of proteins in mammalian biology and disease

项目总结 尽管科学界在阐明许多基因的功能方面取得了实质性进展， 仍有许多未知之处，特别是关于引入到蛋白质中的辅酶和后蛋白的多样性 翻译修饰语。一种这样的修饰是氨基末端乙酰化(NTA)，它相当于 关于哺乳动物N-末端组的研究还很少。蛋白质乙酰化发生在赖氨酸和 蛋白质内的残基(赖氨酸乙酰化或N-ε-乙酰化)和蛋白质N末端的残基(NT-乙酰化 或N--乙酰化)。蛋白质NT-乙酰化是真核蛋白质最常见的修饰之一， 是由N末端乙酰转移酶(NAT)执行的。人NAT在细胞培养中的敲除表型 提示NTA蛋白是人类细胞维持增殖所必需的修饰，但具有功能 缺乏洞察力和哺乳动物体内模型。对NTA的一般作用的理解仍然难以捉摸， 目前已知的NTA影响蛋白质功能、复合体形成、活性或稳定性的例子很少。 我的实验室发现并表征了第一种与N端乙酰化(NTA)相关的遗传病 蛋白质，涉及X连锁基因NAA10的错义突变；我们将这种罕见的疾病命名为奥格登 综合症(OS)，以纪念我们确认为OS的第一个家庭居住的家乡(犹他州奥格登)。这个 受影响的男孩有明显的头面部异常，低眼压，全球发育迟缓， 隐睾症、心脏畸形和心脏增大。然后我们和其他人找到了十几个家庭 在这个途径中有重叠的表型和NAA10的额外突变；我们最近也报道了 编码NAA10结合伙伴的NAA15基因的从头突变与先天性心脏病有关 和/或神经发育。这一发现与心脏异常的范围和 OS(现在更广泛地被称为NAA10相关疾病)中出现的神经发育迟缓。作为我们的一部分 长期着眼于对NTA的机械解剖，未来五年，我们将重点细化 对具有该途径突变的人类进行表型鉴定，同时对独特的小鼠模型进行系统水平的研究， 包括条件等位基因，使用组织学和功能方法提供第一个机械性见解 NTA在心脏发育和哺乳动物生理学中的作用。我们还将继续分析 新发现的途径中的酶，我们认为它可以补偿和防止胚胎死亡 NAA10基因突变的人类和小鼠模型。这笔R35拨款将使分子研究成为可能。 与NAA10和NAA15相关疾病以及NTA途径相关的生物学和病理生理学 这是理解NTA在哺乳动物生物学中的作用的持续努力的一部分。这些研究将是一个关键的 向揭示NTA在人类健康和疾病中的作用迈出一步，因为NTA与癌症有关 进展和神经退行性疾病，包括帕金森氏症、阿尔茨海默氏症和亨廷顿病。

PROJECT SUMMARY Although the scientific community has made substantial progress in elucidating the function of many genes, much remains unknown, particularly concerning the diversity introduced into proteins with co- and post- translational modifications. One such modification is amino-terminal acetylation (NTA), which is considerably understudied, with very few reports on the mammalian N-terminome. Protein acetylation occurs both at lysine residues within proteins (lysine acetylation or N-ε-acetylation) and at the N-terminus of proteins (Nt-acetylation or N--acetylation). Protein Nt-acetylation is among the most common modifications of eukaryotic proteins and is carried out by N-terminal acetyltransferases (NATs). The knockdown phenotypes of human NATs in cell culture suggest that protein NTA is an essential modification in human cells to maintain proliferation, but functional insights and mammalian in vivo models are lacking. Understanding of a general role for NTA remains elusive, and only a few examples in which NTA affects protein function, complex formation, activity, or stability are known. My laboratory discovered and characterized the first genetic disease coupled to N-terminal acetylation (NTA) of proteins, involving a missense mutation in the X-linked gene NAA10; we named this rare disease Ogden syndrome (OS) in honor of the hometown (Ogden, Utah), where the first family we identified with OS lived. The affected boys have a distinct combination of craniofacial anomalies, hypotonia, global developmental delays, cryptorchidism, cardiac anomalies, and cardiomegaly. We and others then found more than a dozen families with overlapping phenotypes with additional mutations in NAA10 in this pathway; we also reported recently that de novo mutations in NAA15, encoding a binding partner for NAA10, are involved in congenital heart defects and/or neurodevelopment. This finding is consistent with the range of cardiac anomalies and neurodevelopmental delays seen in OS (now more broadly known as NAA10-related disorders). As part of our long-term focus on the mechanistic dissection of NTA, over the next five years, we will focus on detailed phenotyping of humans with mutations in the pathway, alongside a systems-level study of unique mouse models, including conditional alleles, using histologic and functional approaches to provide the first mechanistic insights into the role of NTA in cardiac development and mammalian physiology. We will also continue our analysis of a newly identified enzyme in the pathway, which we propose compensates for and prevents embryonic lethality in humans and mouse models with mutations in NAA10. This R35 grant will enable the study of the molecular biology and pathophysiology associated with NAA10- and NAA15-related disorders and the NTA pathway, as part of a sustained effort to understand the role of NTA in mammalian biology. These studies will be a critical step toward revealing the role of NTA in human health and disease, as NTA has been linked to cancer progression and neurodegenerative diseases, including Parkinson’s, Alzheimer’s, and Huntington’s diseases.