MOLECULAR BIOLOGY OF NICOTINIC RECEPTORS

该中心提出了四个假设来研究阿尔法7神经元烟碱型乙酰胆碱受体基因(CHRNA7)的遗传多态在精神分裂症中的作用：(1)CHRNA7的多态与精神分裂症的关系，(2)在细胞水平上证明多态表达的功能效应，(3)多态与与疾病相关的大脑功能障碍的关系，以及(4)针对CHRNA7引起的细胞功能障碍的治疗来逆转大脑功能缺陷。该项目将通过为中心研究人员提供来自活体受试者和死后脑的DNA基因分型，以及对与诊断和功能的关联的体外评估来解决假设1和2。通过多种生物学和遗传学研究，CHRNA7已被认为是染色体15q14连锁区最有可能的候选基因。在CHRNA7基因的近端启动子区域发现了与该基因表达降低一致的功能突变。这些都与精神分裂症和疾病中的P50缺陷有关。在该基因的5‘上游区域还发现了含有多态位点的其他调控区域。本项目AIM 1将完成5‘上游调控区的基因分型，对来自连锁家系的10个先证者的基因剩余部分进行测序，并研究可能影响RNA剪接的相关内含子变体。该区域其他四个基因中的SNPs将被检测为 井。根据审查者的建议，我们还将为另一种具有功能突变的基因COMT提供SNP基因分型，用于与精神分裂症和本项目和其他项目中正在研究的表型有关。对于假设2，目标2将调查CHRNA7突变与对照组和精神分裂症受试者死后脑中CHRNA7 mRNA和蛋白表达的关系。在目标3中，我们将利用微阵列技术，进一步研究CHRNA7相关和功能突变对其他基因表达的影响。CHRNA7突变对CHRNA7本身和其他基因表达的影响可能对该中心的项目具有病理生理学意义。

The Center proposes four postulates for investigating the role of genetic polymorphism in the alpha7 neuronal nicotinic acetylcholine receptor gene (CHRNA7) in schizophrenia: (1) identification and association of polymorphisms in CHRNA7 with schizophrenia, (2) demonstration of a functional effect of the polymorphism expression at the cellular level, (3) relation of the polymorphisms to deficits in brain function associated with the illness, and (4) reversal of the deficits in brain function by treatment directed at the cellular dysfunction caused by CHRNA7. This Project will address Postulates 1 and 2 by providing for the Center Investigators, genotyping of DNA from both live subjects and from postmortem brain, and in vitro evaluation of association with diagnosis and with function. CHRNA7 has been selected as the most likely candidate gene in the chromosome 15q14 linkage region by multiple biological and genetic studies. Functional mutations, consistent with reduced expression of the gene, were found in the proximal promoter region of the CHRNA7 gene. These are associated with both schizophrenia and the P50 deficit in the disease. Additional regulatory regions have been found in the 5' upstream region of the gene that contain polymorphic sites. This Project, Aim 1 will complete genotyping in 5' upstream regulatory regions, sequence the remaining sections of the gene in 10 probands from linked pedigrees, and investigate an associated intronic variant that may affect RNA splicing. SNPs in the four other genes in this region will be examined as well. As suggested by the Reviewers, we will also provide SNP genotyping for another gene with functional mutations, COMT, for association with schizophrenia and the phenotypes being investigated in this and other projects. For Postulate 2, Aim 2 will investigate the association of CHRNA7 mutations with CHRNA7 mRNA and protein expression in human postmortem brain of control and schizophrenic subjects. In Aim 3, we will further investigate the effects of CHRNA7 associated and functional mutations on the expression of other genes, utilizing microarray technology. The consequences of mutations in CHRNA7 on expression of CHRNA7, itself, and of other genes may have pathophysiological importance for the projects in the Center.