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

描述(由申请者提供)：在美国，吸烟是每年约五分之一的过早死亡的原因，毫无疑问，吸烟是导致过早死亡的最可预防的单一原因。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，已有9篇文献报道了烟碱受体基因簇CHRNA5-CHRNA3-CHRNB4中的单核苷酸多态(SNPs)与吸烟相关的多种行为，包括尼古丁依赖、吸烟程度、开始吸烟年龄和吸烟的主观影响。此外，四项研究还报告了同一基因簇中的变异与肺癌风险相关。肺癌和这个基因簇之间的联系是间接的，尽管与吸烟有关，还是代表着一个独立的发现，仍有待确定。无论如何，由于关联结果的多次重复，确定该区域的一个或多个多态影响早逝的单一最可预防的原因和最常见的癌症死亡原因的风险的研究是非常必要的。因此，为了回应RFA-DA-09-003，它基于执行摘要“只关注基因变体的功能特征，这些基因变体被强烈建议与通过候选基因、GWAS和其他方法确定的常见、复杂的人类疾病有关”，我们提出了一系列实验来评估该地区异常强大的候选SNP rs16969968的功能。这个SNP是烟碱受体15亚基中的一个非同义SNP，它导致天冬氨酸在氨基酸位置398位被天冬氨酸取代。我们之前已经证明，这种单核苷酸多态在体外影响142215个尼古丁受体的功能。在本申请中概述的研究中，我们将利用敲门小鼠模型，在该模型中，“处于风险”的天冬酰胺密码子取代了CHRNA5中保护性的天冬氨酸密码子，以解决这种多态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CHRNA5D398N多态是否影响外周神经系统以及非神经细胞(包括支气管上皮细胞和肺癌细胞)中表达的烟碱受体亚型(132415)的功能。 公共卫生相关性：该项目将在小鼠模型中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，并有望提供洞察力，从而可能导致对这些疾病进行更有效的治疗。

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.