TARGET IDENTIFICATION AND MECHANISMS OF ACTIONS OF y-SECRETASE MODULATORS

选择性靶向Abeta42可能是治疗阿尔茨海默病(AD)的理想策略。我们 此前有报道称，某些非甾体抗炎药可调节Abeta42的产生。我们还鉴定出了化合物 ；增加Abeta2.我们现在将这些化合物称为伽马分泌酶调节剂(GSM)。这个 GSM的标志性活性是，它们最小限度地改变总Abeta的产生，但改变了γ-分泌酶 卵裂部位。Abeta42降低GSM增加较短的Abeta多肽和Abeta42升高GSM 减少较短的Abeta多肽。GSM通过一种相对史无前例的机制移动y-裂解。 它们不是以伽马分泌酶为靶标，而是以底物为靶标，从而靶向底物GSM(StGSM)。这些 底物靶向GSM结合底物(APP/APP CTF)和产物(Abeta)在对应的区域 到Abeta的29-36位残基。Abeta的这个区域对于聚集是至关重要的。我们发现，stGSM实际上是这样做的 抑制Abeta聚集，许多被鉴定为聚集抑制剂的化合物是GSM。这些 研究结果表明，stGSM有两个潜在的治疗作用，改变Abeta42的产生和 抑制Abeta聚集，可能协同减少AD中Abeta的沉积。作为更短的Abeta 多肽也可能具有保护作用，可能是GSM增加了这些短肽的水平 也可能有第三种有益的治疗作用。在这项提案中，我们将扩展机械论研究 关于GSM的底物靶向和评估关于GSM体内机制的相关假说 全球海洋管理措施的行动。我们将进行急性和慢性剂量研究，使用Abeta42降低和提高GSM 在APP和BRI-Abeta42小鼠模型中评估改变Abeta42产量的相对贡献 相对于改变聚集对Abeta负荷和其他类似AD的病理的影响。活体内的这些 研究将使我们能够模拟在项目3的人体试验中看到的可能的变化。密切合作 在项目1中，我们还将确定较短的Abeta多肽的海拔是否具有保护作用。对于以后的这些 研究我们将使用重组腺相关病毒(RAAV)来传递BRI-Abeta融合构建物 将短的Abeta多肽编码到新生APP小鼠的大脑。这种方法论创造了“躯体大脑” 转基因“，这将使我们能够快速评估较短的Abeta多肽对Abeta沉积的影响。 总的来说，这些研究应该为GSM转移Abeta的机制提供更多的洞察力 卵裂及其在体内的保护作用。

Selective targeting of Abeta42 may be an ideal therapeutic strategy for Alzheimer's disease (AD). We Deviously reported that certain NSAIDs modulate Abeta42 production. We have also identified compounds ;hat increase Abeta2. We now refer to these compounds as gamma-secretase modulators (GSMs). The signature activity of GSMs is that they minimally alter total Abeta production but shift the y-secretase cleavage site. Abeta42 lowering GSMs increase shorter Abeta peptides and Abeta42 raising GSMs decrease shorter Abeta peptides. GSMs shift y-cleavagethrough a relatively unprecedented mechanism. Instead of targeting gamma-secretase, they target substrate hence substrate-targeting GSM (stGSM). These substrate-targeting GSMs bind substrate (APP/APP CTF) and product (Abeta) in a region that corresponds to residues 29-36 of Abeta. This region of Abeta is critical for aggregation. We find that stGSMs do in fact nhibit Abeta aggregation, and that many compounds identified as aggregation inhibitors are GSMs. These findings suggest that stGSMs have two potential therapeutic actions, alteration in Abeta42 production and nhibition of Abeta aggregation, that may synergistically reduce Abeta deposition in AD. As shorter Abeta peptides may also be protective, it is possible that GSMs which increase the levels of these shorter peptides may also have a third beneficial therapeutic action. In this proposal we will extend mechanistic studies regarding substrate targeting by GSMs and evaluate linked hypotheses regarding the in vivo mechanism of action of GSMs. We will perform acute and chronic dosing studies with Abeta42 lowering and raising GSMs in APP and BRI-Abeta42 mouse models to evaluate the relative contribution of altering Abeta42 production vs. altering aggregation with respect to effect on Abeta loads and other AD-like pathologies. These in vivo studies will enable us to model possible changes seen in human trials in Project 3. In close collaboration with Project 1, we will also determine if elevations in shorter Abeta peptides are protective. For these later studies we will use recombinant adenoassociated virus (rAAV) to deliver BRI-Abeta fusion constructs encoding short Abeta peptides to the brain of neonatal APP mice. This methodology creates "somatic brain transgenics" and will allow us to rapidly evaluate the effects of shorter Abeta peptides on Abeta deposition. Collectively, these studies should provide additional insight into the mechanism whereby GSMs shift Abeta cleavage and their protective effects in vivo.