New Roles for sAPP in Neuroprotection and Neurogenesis

淀粉样前体蛋白及其可溶性分泌片段a的神经保护作用 正常的a-分泌酶裂解产物，已经在培养系统中被证明是对广泛的 一连串的神经元侮辱。在某些转基因(TG)小鼠模型中观察到的几种保护作用 过度表达的APP也被推断为Sappa。这些行动背后的机制是 然而，几乎没有人研究过。因此，这一应用的目的是研究分子 Sappa的作用机制及其对神经病理的改善作用 鼠标AD模型。在初步研究中，我们证明了缺乏APP的小鼠或细胞与 应激激酶CDK5活性增加和tau磷酸化增加，这可以通过以下方法恢复 外源Sappa。Sappa在NMDA诱导的神经元死亡中具有较强的抗凋亡活性 它通过参与Bcl2的途径与IGF协同作用。重要的是，我们在青少年中发现神经性缺陷 并在各种细胞/组织培养中鉴定了sAPP的神经营养功能，这是 由EGF协同作用。成年小鼠慢性输注Sappa后，神经前体细胞在 脑室下区含有体内Sappa的主要结合部位。Sappa优先绑定到 细胞表面富含脂质的微区。综上所述，我们假设萨帕发挥了广泛的作用 神经保护在防止神经元退化和死亡中的作用，以及更多关于Quinalv的关键作用 出生前和出生后两个阶段的神经衰弱。SAPA在中枢神经系统治疗中的适当剂量和 时机选择将改善小鼠AD模型中出现的神经病理学。因此，我们在目标1中建议 评价Sappa在减轻Tau TG小鼠模型神经病变中的作用。我们将测试 Sappa治疗是否能减少tau-磷酸化和NFT的形成，提供兴奋保护， 并使用tau突变(R406W)转基因小鼠防止记忆丧失。目标2将评估潜在的 Sappa在APP“‘*和APP/APLP2双基因敲除小鼠神经发生中的作用 这些小鼠的神经发生水平是否与它们的死亡率有关，以及慢性输注 Sappa可刺激这些小鼠神经前体/干细胞的增殖并挽救神经发生 减损。目标3是了解生物学上的分子和细胞机制。 Sappa的功能和鉴定Sappa相关膜蛋白(S)。分子和细胞 生物方法，包括膜蛋白与结合的生物素化的Sappa、脂筏 分离，结合蛋白质组学技术，将被用于分离和鉴定推定的 Sappa的膜受体S我们的研究将揭示APP/Sappa AS的新生理功能 以及潜在的分子机制，并应揭示潜在的治疗窗口 未来的萨帕。

The neuroprotective roles for amyloid precursor protein (APR) and its soluble secreted fragment (sAPPa), a normal a-secretase cleavage product, have been demonstrated in culture systems against a broad spectrum of neuronal insults. Several protective roles observed in certain transgenic (Tg) mouse models overexpressing APP have also been inferred to sAPPa. The mechanisms underlying these actions, are however, scarcely studied. The objectives of this application are thus to investigate the molecular mechanisms of sAPPa's functions and to evaluate its beneficial effects on alleviating neuropathologies in mouse AD models. In preliminary studies, we demonstrated that mice or cells lacking APP are associated with increased stress kinase CDK5 activity and elevated tau phosphorylation, which can be restored by exogenous sAPPa. sAPPa possesses strong anti-apoptotic activity in NMDA-induced neuronal death which synergizes with IGF via a pathway involving Bcl-2. Importantly, we found neurogenic defect in young adult APP"'" mice and identified a neurotrophic function of sAPPain various cell/tissue cultures, which is synergized by EGF. Chronic infusion of sAPPa into adult mice reveals that the neuronal progenitor cells in the subventricular zone contain major binding sites for sAPPa in vivo. sAPPa preferentially binds to the lipid-enriched microdomains on the cell surface. Taken together, we hypothesize that sAPPa plays broad neuroprotective roles in preventing neuronal degeneration and death, and more intriQuinalv, a crucialrole in neuropenesis at both the prenatal and postnatal stages. sAPPa treatment in CNS at a proper dosage and timing will improve neuropathologies developed in mouse AD models. We therefore propose in Aim 1 to assess the roles of sAPPa in reducing neuropathologies in Tau Tg mouse model. We will test whether sAPPa treatment can reduce tau-phosphorylation and NFT formation, provide excitoprotection, and prevent memory loss using tau mutant (R406W) transgenic mice. Aim 2 will assess the potential roles of sAPPa in neurogenesis in APP"'* and APP/APLP2 double knockout mice. We will examine whether neurogenesis levels in these mice associate with their mortality, and whether chronic infusion of sAPPa can stimulate proliferation of neuronal progenitor/stem cells in these mice and rescue neurogenesis impairment. Aim 3 is to understand the molecular and cellular mechanism underlying the biological functions of sAPPa and to identify sAPPa-associated membrane protein(s). Molecular and cell biological approaches including crosslinking of membrane proteins with bound biotinylated sAPPa, lipid raft isolation, in combination with proteomic technologies, will be used to isolate and identify putative membrane-receptor(s) for sAPPa.. Our study will reveal novel physiological functions of APP/sAPPa as well as the underlying molecular mechanisms, and should shed light on potential therapeutic windows for sAPPa in the future.