New Roles for sAPP in Neuroprotection and Neurogenesis

淀粉样前体蛋白（APR）及其可溶性分泌片段（sAPPa）的神经保护作用 正常的α-分泌酶裂解产物，已经在培养系统中证明了对广泛的 神经元损伤谱。在某些转基因（Tg）小鼠模型中观察到的几种保护作用 过表达APP也被推断为sAPPa。这些行动的机制是 然而，几乎没有研究。因此，本申请的目的是研究分子生物学。 sAPPa的功能机制并评估其对缓解神经病理学的有益作用 小鼠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CDK 5活性增加，tau蛋白磷酸化水平升高， 外源性sAPPa。sAPPa在NMDA诱导的神经元死亡中具有强的抗凋亡活性 其通过涉及Bcl-2的途径与IGF协同作用。重要的是，我们发现年轻人的神经源性缺陷 成年APP小鼠，并鉴定了sAPP蛋白各种细胞/组织培养物的神经营养功能， EGF的功效将sAPPa慢性输注到成年小鼠中揭示了在小鼠中的神经元祖细胞， 脑室下区含有sAPPa在体内的主要结合位点。sAPPa优先结合 细胞表面的脂质富集微区。综上所述，我们假设sAPPa在广泛的 神经保护作用，防止神经元变性和死亡，更重要的是，Quinalv，一个关键的作用， 产前和产后阶段的神经衰弱。以适当剂量在CNS中进行sAPPa治疗， 时机将改善小鼠AD模型中发展的神经病理学。因此，我们在目标1中建议， 评估sAPPa在Tau Tg小鼠模型中减少神经病理学中的作用。我们将测试 sAPPa治疗是否可以减少tau-磷酸化和NFT形成，提供兴奋保护， 并使用tau突变体（R406 W）转基因小鼠预防记忆丧失。目标2将评估潜力 sAPPa在APP +/+和APP/APLP 2双敲除小鼠中神经发生中的作用。我们将研究 这些小鼠的神经发生水平是否与其死亡率相关，以及慢性输注 sAPPa可以刺激这些小鼠中神经元祖细胞/干细胞的增殖并拯救神经发生 损伤目的3是了解生物学的分子和细胞机制， sAPPa的功能和鉴定sAPPa相关膜蛋白。分子和细胞 生物学方法包括膜蛋白与结合的生物素化sAPPa、脂筏 分离，结合蛋白质组学技术，将用于分离和鉴定推定的 膜受体（s）sAPPa..我们的研究将揭示APP/sAPPa的新的生理功能， 以及潜在的分子机制，并应阐明潜在的治疗窗口， sAPPa在未来

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.