Function of the CHRNA5 D398N SNP: implications for addiction and lung cancer ris

描述（由申请人提供）：在美国，吸烟每年造成大约五分之一的过早死亡，毫无疑问，吸烟是导致过早死亡的最可预防的原因。此外，主要由吸烟引起的肺癌是美国癌症死亡的主要原因。近年来，有9篇文献报道了烟碱受体基因簇CHRNA 5-CHRNA 3-CHRNB 4的单核苷酸多态性（single nucleotide polymorphism，SNPs）与尼古丁依赖、吸烟水平、开始吸烟年龄和吸烟主观效应等多种吸烟相关行为相关。此外，四项研究还报告说，同一基因簇中的变异与肺癌风险有关。肺癌与该基因簇之间的关联是否是间接的（尽管与吸烟有关）或代表一个独立的发现仍有待确定。无论如何，由于相关研究结果的多次重复，确定该区域中影响过早死亡的单一最可预防原因和癌症死亡的最常见原因的多态性的研究是非常必要的。因此，为了响应RFA-DA-09-003，其基于执行摘要“仅关注基因变体的功能表征，这些基因变体强烈建议与通过候选基因GWAS和其他方法鉴定的常见复杂人类疾病相关”，我们提出了一系列实验来评估该区域rs 16969968中异常强的候选SNP的功能。该SNP是烟碱受体15亚基中的非同义SNP，其导致在氨基酸位置398处天冬酰胺取代天冬氨酸。我们以前已经表明，这种SNP影响142215烟碱受体在体外的功能。在本申请中概述的研究中，我们将利用敲入小鼠模型，其中“有风险”的天冬酰胺密码子已经取代了Chrna 5中的保护性天冬氨酸密码子，以解决该多态性与脑功能和肺癌易感性的功能相关性。我们还将利用体外实验来确定CHRNA 5 D398 N多态性是否影响烟碱受体（132415）亚型的功能，所述烟碱受体亚型在外周神经系统以及非神经元细胞（包括支气管上皮细胞和肺癌细胞系）中表达。 公共卫生相关性： 该项目将测试与人类尼古丁依赖和肺癌风险相关的特定突变是否会影响小鼠模型的脑功能和肺癌易感性。结果将导致更好地了解这些疾病的遗传学，并希望提供可能导致更有效治疗这些疾病的见解。

DESCRIPTION (provided by applicant): Smoking is responsible for approximately one in five premature deaths each year in the USA making it, without question, the single most preventable cause of premature death. In addition, lung cancer, which is predominantly caused by smoking, is the leading cause of cancer deaths in the USA. Recently, a series of 9 papers all reported that single nucleotide polymorphisms (SNPs) within the nicotinic receptor gene cluster CHRNA5-CHRNA3-CHRNB4 are associated with various smoking-related behaviors including nicotine dependence, level of smoking, age of initiation and subjective effects of smoking. Moreover, four studies also reported that variants in this same gene cluster are associated with risk for lung cancer. Whether the association between lung cancer and this gene cluster is indirect though the association with smoking or represents an independent finding remains to be determined. Regardless, due to the multiple replications of the association findings, studies to identify the polymorphism or polymorphisms in this region that influences risk for the single most preventable cause of premature death and the most common cause of cancer death are highly warranted. Therefore, in response to RFA-DA-09-003, which based upon the executive summary "focuses solely on functional characterization of gene variants which are strongly suggested to be associated with common, complex human diseases identified through candidate gene, GWAS, and other approaches", we propose a series of experiments to evaluate the function of an exceptionally strong candidate SNP in this region, rs16969968. This SNP is a non-synonymous SNP in the nicotinic receptor 15 subunit that leads to an asparagine for aspartic acid substitution at amino acid position 398. We previously have shown that this SNP affect the function of 142215 nicotinic receptors in vitro. In the studies outlined in this application, we will utilize a knockin mouse model in which the "at risk" asparagine codon has replaced the protective aspartic acid codon in Chrna5 to address the functional relevance of this polymorphism with regards to brain function and lung cancer susceptibility. We also will utilize in vitro experiments to determine whether the CHRNA5 D398N polymorphism affects the function of a subtype of nicotinic receptor (132415) that are expressed in the peripheral nervous system as well as in non-neuronal cells, including bronchial epithelial cells and lung cancer cell lines. PUBLIC HEALTH RELEVANCE: This project will test whether a specific mutation that is associated with risk for nicotine dependence and lung cancer in humans affects brain function and lung cancer susceptibility in a mouse model. Results will lead to a better appreciation of the genetics of these diseases and hopefully provide insight that may lead to more effective treatments for these conditions.