APP-BP1, The Cell Cycle, and Alzheimer Disease

描述(申请人提供)：我们已经确定了一种与淀粉样前体蛋白(APP)的细胞内结构域相互作用的细胞周期蛋白。这种名为APP-BP1的蛋白质驱动细胞周期通过S-M检查点进行细胞分裂。APP-BP1在神经元中的过度表达会导致神经元死亡。值得注意的是，APP的家族性阿尔茨海默病(FAD)突变体在神经元中的表达导致(1)APP-BP1表达增加，(2)神经元进入细胞周期的S期，(3)神经元凋亡。此外，与对照组相比，APP-BP1在AD大脑的高危区域过表达。APP-BP1代表了第一批真正的“句柄”之一，用于确定AD患者细胞周期调节和DNA复制丢失背后的机制。我们认为APP和APP-BP1的相互作用对于正常的脑功能是重要的，但在AD中，这两个蛋白之间的相互作用的调节出现了偏差，导致神经元的细胞周期调节失败。以下具体目标验证了这一假设： 1.我们将开始定义APP-BP1与APP相互作用激活的信号转导通路，其异常激活可能导致神经元进入细胞周期，导致细胞凋亡。 2.APP-BP1参与一种新的泛素化相关途径，涉及泛素样分子NEDD8。我们将使用免疫荧光和共聚焦显微镜来确定APP-BP1、NEDD8、ASPP2和泛素化相关途径中的其他分子所在的亚细胞结构，在培养的原代神经元和对照组以及AD死后脑中。 3.从完成特定目标1和2获得的数据将提示APP-BP1介导的信号干扰的特定后果，我们可能会在死后AD脑中观察到这些结果。我们将检验这些预测是否正确。

DESCRIPTION (provided by applicant): We have identified a cell cycle protein that interacts with the intracellular domain of the amyloid precursor protein (APP). This protein, APP-BP1, drives the cell cycle through the S-M checkpoint in dividing cells. Overexpression of APP-BP1 in neurons causes them to die. Notably, expression of familial Alzheimer disease (FAD) mutants of APP in neurons results in (1) an increase in expression of APP-BP1, (2) entry of the neurons into the S phase of the cell cycle, and (3) neuronal apoptosis. Furthermore, APP-BP1 is overexpressed in at-risk regions of AD brain relative to controls. APP-BP1 represents one of the first real "handles" for determining the mechanism behind the loss of cell cycle regulation and DNA replication that appears to occur in AD. We propose that the interaction of APP with APP-BP1 is important for normal brain function, but that the regulation of the interaction between the two proteins goes awry in AD, resulting in cell cycle regulatory failure in neurons. The following specific aims test this hypothesis: 1. We will begin to define the signal transduction pathway that is activated by interaction of APP-BP1 with APP, and whose abnormal activation may cause entry of neurons into the cell cycle, resulting in apoptosis. 2. APP-BP1 participates in a novel ubiquitination-related pathway involving the ubiquitin-like molecule NEDD8. We will use immunofluorescence and confocal microscopy to identify the subcellular structures in which APP-BP1, NEDD8, ASPP2, and other molecules in the ubiquitinylation-related pathway reside, in primary neurons in culture and in control and AD postmortem brains. 3. The data obtained from accomplishment of specific aims 1 and 2 will suggest specific consequences of perturbations of APP-BP1-mediated signaling that we might expect to observe in postmortem AD brain. We will test whether these predictions are correct.