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

描述（由申请人提供）：在美国，吸烟每年导致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。最近，一系列9篇论文均报道了尼古丁受体基因簇CHRNA5-CHRNA3-CHRNB4内的单核苷酸多态性（snp）与尼古丁依赖、吸烟水平、开始吸烟年龄和吸烟的主观影响等多种吸烟相关行为有关。此外，四项研究还报告了同一基因簇的变异与肺癌风险相关。肺癌和这一基因簇之间的联系是间接的，还是代表着一个独立的发现，还有待确定。无论如何，由于相关发现的多次重复，确定该区域的多态性或多态性的研究是非常有必要的，这些多态性会影响最可预防的单一过早死亡原因和最常见的癌症死亡原因的风险。因此，RFA-DA-09-003基于执行摘要“仅关注通过候选基因、GWAS和其他方法鉴定出与常见、复杂的人类疾病相关的基因变异的功能表征”，我们提出了一系列实验来评估该区域一个异常强的候选SNP rs16969968的功能。该SNP是烟碱受体15亚基的非同义SNP，导致398个氨基酸位置的天冬氨酸取代天冬氨酸。我们之前已经在体外证明了该SNP影响142215烟碱受体的功能。在本应用程序中概述的研究中，我们将利用敲入小鼠模型，其中“危险”天冬酰胺密码子取代了Chrna5中的保护性天冬氨酸密码子，以解决这种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CHRNA5 D398N多态性是否影响烟碱受体（132415）亚型的功能，该亚型在周围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。

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.