APOBEC3-mediated damage of host genomic DNA in vivo

描述(申请人提供)：所有哺乳动物基因组编码一个或多个APOBEC3(A3)基因、胞苷脱氨酶(CDA)，它们是固有的抗病毒限制因子，可抑制多种病毒的感染，包括逆转录病毒、细小病毒、肝炎病毒、乳头瘤病毒，甚至疱疹病毒。虽然这些CDA对抗病毒免疫至关重要，但它们也有可能作用于基因组DNA，因此它们的表达可能会以基因组完整性为代价。事实上，有越来越多的证据表明，A3蛋白作用于细胞DNA，导致突变。我们的实验室率先使用A3基因敲除小鼠来研究它们在地方性逆转录病毒感染中的作用，最近创造了在体内表达功能蛋白的人A3A和3G转基因小鼠。我们建议使用野生型、基因敲除和转基因小鼠来直接测试体内是否发生基因组DNA损伤或突变，以及这些突变是否会导致长寿和与年龄相关的疾病，如癌症。我们将在野生型、基因敲除和转基因小鼠以及LacZ突变小鼠中研究这些过程，从而可以方便地评估不同组织中的非致命性突变率。此外，我们将通过将KO和转基因小鼠与APCmin小鼠杂交，确定小鼠和人类A3蛋白是否导致在人类结直肠癌中频繁突变的APC抑癌基因的突变。我们预计，在APOBEC+小鼠中，突变将以比A3基因敲除小鼠更快的速度积累，特别是那些表达人A3蛋白的小鼠，并且它们将表现出CDA介导的突变的特征特征。这些小鼠为我们提供了独特的能力来监测在不同组织中出现的突变的频谱，并将为我们提供一个直接测试 A3蛋白在体内引起DNA突变和损害的潜在能力对长期健康有影响。鉴于A3基因在特定人类癌症中的表达与将A3活性作为潜在的抗病毒疗法的重点之间的联系，了解A3是否介导基因组损伤尤其重要。这项研究可能 建立一个新的衰老研究领域，由于A3基因被认为在抗病毒免疫中发挥主要作用(如果不是唯一的话)，因此考虑采用靶向治疗来限制它们引起基因组DNA突变的能力是可行的。

DESCRIPTION (provided by applicant): All mammalian genomes encode one or more APOBEC3 (A3) genes, cytidine deaminases (CDAs) that are intrinsic anti-viral restriction factors, inhibiting infection by a diverse array of viruses including retroviruses, parvoviruses, hepadnaviruses, and papillomaviruses and perhaps even herpes viruses. While these CDAs are critical to anti-viral immunity, they also have the potential to act on genomic DNA and thus their expression may come at a cost to genomic integrity. Indeed, there is accumulating evidence that A3 proteins act on cellular DNA, resulting in mutations. Our lab pioneered the use of A3 knockout mice to study their role in endemic retrovirus infection and have recently created human A3A and 3G transgenic mice that express functional protein in vivo. We propose to use wild type, knockout, and transgenic mice to directly test if genomic DNA damage or mutation occurs in vivo and whether such mutations have consequences for longevity and age-related diseases such as cancer. We will study these processes in wild type, knockout and transgenic mice, as well as lacZ mutator mice, which allow facile evaluation of non-lethal mutation rates in different tissues. Additionally, we will determine whether the mouse and human A3 proteins cause mutations in the APC tumor suppressor gene frequently mutated in human colorectal cancer, by crossing the KO and transgenic mice with APCmin mice. We expect that mutations will accumulate with age at a more rapid rate in APOBEC+ mice, particularly those expressing human A3 proteins, than in A3 knockout mice and that they will show characteristic signatures of CDA-mediated mutations. These mice afford us the unique ability to monitor the spectrum of mutations that arise in different tissues and will provide us with a model to directly test whether A3 proteins' potential ability to cause DNA mutations and damage in vivo has consequences for long-term health. It is particularly important to know whether A3 mediates genomic damage, given the association between the expression of A3 genes in particular human cancers, as well as the focus on targeting A3 activity as potential anti-viral therapies in humans. This study could establish a new area of aging research and since A3 genes are believed to function predominantly if not solely in antiviral immunity, it would be feasible to consider targeted therapies that limit their ability to cause genomic DNA mutation.