Roles of PS1 in y-secretase integrity and trafficking

描述（由申请人提供）：早老素（PS，PS1/PS2）中的基因突变是早发性家族性阿尔茨海默病（FAD）的主要原因。 PS是γ-分泌酶复合物的推定催化组分。 γ-分泌酶介导淀粉样前体蛋白（APP）的膜内切割，其产生阿尔茨海默病（AD）中的致病性小肽Abeta。 到目前为止，PS、Nicastrin（Net）、Aph-1和PEN-2已被确定为其基本组分。 它们是在ER中合成并通过分泌途径行进的整合膜蛋白。 PS1已被证明在γ-分泌酶组分Net的细胞内运输中发挥作用。 在我的初步研究中，我发现在没有PS的情况下，PEN-2以较短的半衰期保留在ER中，这表明PS是PEN-2的运输和稳定所必需的，可能是通过物理相互作用。 此外，某些γ-分泌酶抑制剂处理导致细胞表面结合的PS1和PEN-2显著增加，但Net不增加。 这是第一次，高选择性的有效γ-分泌酶抑制剂已被证明差异影响γ-分泌酶组分的运输。 由于这些γ-分泌酶抑制剂已被证明是物理结合PS1，我假设他们对γ-分泌酶成分的影响是由PS1介导的。 事实上，我的初步数据进一步证明，内源性PEN-2诱导的细胞表面积累依赖于PS1。 基于这些结果，我提出PS及其相关的γ-分泌酶活性对于维持γ-分泌酶复合物的完整性和适当的细胞内运输至关重要。 因此，本提案的目的是检验这一假设。 将系统地研究PS1突变（特异性Aim 1）改变PS1功能对γ-分泌酶复合物的完整性和运输特性的影响。 这些研究将揭示PS1突变的细胞扰动机制，包括导致AD发病的机制。 此外，详细分析γ-分泌酶抑制剂如何影响γ-分泌酶组分的运输（具体目标2），特别是它们是否对PS1突变体具有相同的作用（具体目标3），应为药物设计提供有价值的信息，以减缓并最终预防AD。

DESCRIPTION (provided by applicant): Genetic mutations in presenilins (PSs, PS1/PS2) account for the majority of early-onset familial Alzheimer's disease (FAD). PS is the putative catalytic component of gamma-secretase complex. Gamma-secretase mediates the intramembrane cleavage of amyloid precursor protein (APP) that generates pathogenic small peptide Abeta in Alzheimer's disease (AD). So far, PSs, Nicastrin (Net), Aph-1, and PEN-2 have been identified as its essential components. They are integral membrane proteins that are synthesized in ER and travel through the secretory pathway. PS1 has been shown to play roles in intracellular trafficking of gamma-secretase component Net. In my preliminary studies, I found that in the absence of PS, PEN-2 is retained in the ER with a shorter half-life, suggesting PS is required for the trafficking and stability of PEN-2, probably via physical interaction. Furthermore, certain gamma-secretase inhibitor treatment results in markedly increased cell surface bound PS1 and PEN-2, but not Net. This is the first time that highly selective potent gamma-secretase inhibitors has been shown to differentially affect the trafficking of gamma-secretase components. Since these gamma-secretase inhibitors have been shown to physically bind PS1,I hypothesized that their effect on the gamma-secretase components is mediated by PS1. Indeed, my preliminary data further demonstrated that the inhibitor-induced cell surface accumulation of PEN-2 depends on PS1. Based on these results, I propose that PS and its associated gamma-secretase activity are critical for maintaining the integrity and proper intracellular trafficking of the gamma-secretase complex. The objective of this proposal is therefore to test this hypothesis. The impact of altered PS1 function by PS1 mutation (Specific Aim1) on the integrity and trafficking property of gamma-secretase complex will be systemically examined. These studies will reveal the mechanism of the cellular perturbation underlying PS1 mutations, including which results in pathogenesis of AD. Furthermore, detailed analysis of how gamma-secretase inhibitors affect the trafficking of gamma-secretase components (Specific Aim 2), especially whether they have the same effect toward PS1 mutants (Specific Aim 3) should provide valuable information for drug design to slow and ultimately prevent AD.