A gene expression study of regional vulnerability in Alzheimer's disease

描述（由申请人提供）：神经退行性疾病的一个重要问题是区域脆弱性问题。当大多数潜在的致病基因无处不在地表达时，为什么首先针对特定大脑区域的特定细胞类型？在阿尔茨海默病（AD）中，PSEN1、PSEN2和APP突变在大多数情况下导致典型的神经退行性变，首先是CA1海马锥体细胞的退行性变，随后是结构相似的CAS锥体神经元、后顶叶、上顶叶的退行性变，最终是大部分大脑皮层的退行性变，保留小脑和初级感觉皮层。散发性阿尔茨海默病，其中特异性孟德尔突变尚未确定，导致本质上相同的疾病进展。我们假设相对不易受AD病理影响的区域表达提供相对保护的基因模式，并且更脆弱区域的基因表达变化反映了它们的脆弱性。同样，对神经变性的易感性并不发生在整个组织水平上，而是发生在特定的细胞类型上。因此，通过比较结构相似的神经元或海马区（CA1和CAS）中对AD病理有不同易感性的基因表达，将揭示AD神经保护和易感性的靶点。我们将利用激光捕获显微解剖技术，从对照组和晚期阿尔茨海默病患者易受阿尔茨海默病病理影响的CA1和相对不易受阿尔茨海默病病理影响的CAS中提取健康的锥体细胞。从这些区域的细胞池中扩增的cRNA将被杂交到定制的微阵列中，并使用标准方法分析差异表达基因。此外，每个区域特有的转录网络将使用加权基因共表达网络分析（WGCNA）来识别，这是一种发现转录组组织的强大新方法。总的来说，将在六种情况下收集表达数据：1)控制CA1, 2) CAS, 3)视极，以及4)病变CA1, 5) CAS, 6)视极，其中视极被包括作为基本不受AD影响的控制脑区。这些数据将用于通过区域比较和对照/疾病比较来确定与AD的相对保护和易感性相关的转录网络。通过围绕寻找神经保护基因设计实验，本实验计划将发现新的阿尔茨海默病靶基因，这可能对阿尔茨海默病的早期诊断和治疗具有潜力。

DESCRIPTION (provided by applicant): An important issue in neurodegenerative disorders is the issue of regional vulnerability. Why are specific cell types in specific brain regions targeted first, when most of the underlying disease-causing genes are expressed ubiquitously? In the case of Alzheimer's disease (AD), PSEN1, PSEN2, and APP mutations lead to a typical pattern of neurodegeneration in most cases, starting with degeneration of CA1 hippocampal pyramidal cells, followed later by degeneration of the structurally similar CAS pyramidal neurons, posterior, superior parietal lobe, and eventually by degeneration of most of the cerebral cortices, sparing cerebellum and primary sensory cortices. Sporadic AD, where specific Mendelian mutations have not been identified, leads to essentially the same disease progression. We hypothesize that regions relatively invulnerable to AD pathology express patterns of genes that provide relative protection, and that gene expression changes in more vulnerable regions reflect their vulnerability. Similarly, susceptibility to neurodegeneration does not occur on a whole tissue level, but rather in specific cell types. Therefore, by comparing gene expression in structurally similar neurons or regions of the hippocampus (CA1 and CAS) that are differentially vulnerable to AD pathology, targets for AD neuroprotection and susceptibility will be uncovered. Healthy pyramidal cells will be extracted from both CA1, which is vulnerable to AD pathology, and CAS, which is relatively less vulnerable, in both controls and individuals with advanced AD using laser capture microdissection. Amplified cRNA from pools of cells in these regions will then be hybridized to custom microarrays, and analyzed for differentially expressed genes using standard methods. Additionally, the transcriptional networks specific to each region will be identified using weighted gene co-expression network analysis (WGCNA), a powerful new method for uncovering transcriptomic organization. In all, expression data will be collected under six conditions: 1) Control CA1, 2) CAS, and 3) visual pole, as well as 4) diseased CA1, 5) CAS, and 6) visual pole, where visual pole is included as a control brain region that remains essentially unaffected by AD. These data will be used to determine the transcriptional network related to relative protection and susceptibility in AD through regional comparisons and control/disease comparisons. By designing our experiment around finding neuroprotective genes, this experimental plan will uncover novel target genes for AD, which may have the potential for early diagnoses and treatment of AD.