MODULATION OF APP METABOLISM BY X11ALPHA/MINT-1

神经元接头蛋白X11alpha/mint-1与淀粉样蛋白前体蛋白（APP）相互作用，调节其在体外的运输和加工。在转染的非神经元细胞中，X11alpha抑制APP的α -和γ -切割，但不抑制β -切割。由于X11alpha的磷酸酪氨酸结合（PTB）结构域与APP家族特异性相互作用，X11alpha似乎特异性抑制APP的γ -切割，同时保留Notch和其他膜内蛋白水解调节底物的γ -切割。为了确定这些体外数据在体内的意义，我们将产生并表征新型hX11alpha转基因小鼠和X11alpha敲除小鼠，并检测小鼠APP代谢。将这些小鼠与Tg2576小鼠（瑞典基因突变hAPP或hAPPswe的转基因小鼠）杂交，将探讨XI la对衰老大脑中hAPPswe代谢和部分ad样表型发展的影响。最近的一项人类全基因组分析显示，散发性阿尔茨海默病与9号染色体上的单核苷酸多态性（snp）有显著联系，可能包括x11 α区域。我们将利用从AD受试者和精心匹配的对照受试者的样本中提取的基因组DNA，探索X11alpha区域的snp与散发性AD的遗传联系。具体目标是：1)生成X11alpha敲除和hX11alpha转基因小鼠，并确定对小鼠脑和原代神经元培养物中APP代谢的影响；2)将X11alpha敲除和hX11alpha转基因小鼠与Tg2576小鼠杂交，以确定a)对脑和神经元培养物中hAPPswe代谢的调节作用；b) AD样表型随着年龄的增长而发展；3)阐明AD病例中X11alpha基因内或邻近基因的snp和单倍型，以及年龄、性别。和apoe匹配的对照，以确定是否与散发性阿尔茨海默病有统计学意义的联系。具体目标3将研究从病理学核心和其他adrc获得的DNA样本。这些结果将1)通知正常功能

The neuronal adaptor protein X11alpha/mint-1 interacts with amyloid precursor protein (APP) to regulate its trafficking and processing in vitro. In transfected non-neuronal cells, X11alpha inhibits alpha- and gamma- but not beta- cleavage of APP. Because the phosphotyrosine binding (PTB) domain of X11alpha interacts specifically with the APP family, X11alpha appears to inhibit gamma-cleavage of APP specifically while sparing gamma-cleavage of Notch and other substrates of regulated intramembranous proteolysis. To determine the in vivo significance of these in vitro data, we will generate and characterize novel hX11alpha transgenic mice and X11alpha knockout mice and examine murine APP metabolism. Crosses of these mice to Tg2576 mice (transgenic for the Swedish mutation of hAPP, or hAPPswe) will probe the effects of XI la on hAPPswe metabolism and on the development of partial AD-like phenotypes in aging brain. A recent human genome-wide analysis revealed significant linkage of sporadic AD to single nucleotide polymorphisms (SNPs) on chromosome 9, perhaps including the X11alpha region. We will probe genetic linkage of SNPs in the X11alpha region to sporadic AD by using genomic DNA extracted from samples from AD subjects versus carefully-matched control subjects. The specific aims are to: 1) generate X11alpha knockout and hX11alpha transgenic mice and determine effects on murine APP metabolism in brain and in primary neuronal cultures, 2) cross X11alpha knockout and hX11alpha transgenic mice with Tg2576 mice to determine a) modulatory effects on hAPPswe metabolism in brain and in neuronal cultures, and b) development of AD-like phenotypes with aging, and 3) elucidate the SNPs and haplotypes within or adjacent to the X11alpha gene of AD cases and age-, gender-, and ApoE-matched controls to determine if there is a statistically significant link to sporadic AD. Specific aim 3 will study DNA samples obtained from the Pathology Core and from other ADRCs. These results will 1) inform the normal functions of X11alpha as well as APP and its derivatives in CNS neurons, 2) lay the groundwork for viral-vector based gene therapy of AD using either X11alpha or its PTB domain in hAPP transgenic mouse models, and 3) probe a potential genetic risk factor of sporadic AD.