The Role of Gamma-Secretase in Human Neuronal Physiology

摘要 阿尔茨海默氏症(AD)是美国痴呆症的主要原因，影响着570万美国人， 然而，目前还没有治疗方法。早发性AD最常见的原因是早老素的家族性突变， 蛋白酶g-分泌酶的催化亚基。突变的𝛾-分泌酶切割淀粉样前体蛋白(APP) 并释放与突触丢失相关的有毒的b-淀粉样多肽。然而，𝛾分泌酶也可能起到一定作用 通过APP处理以外的机制导致AD中的突触功能障碍。而𝛾-分泌酶有助于 AD病理中，它在维持人类突触正常功能方面的更广泛的生理作用很差 明白了。来自非神经细胞和小鼠模型的证据表明，𝛾-分泌酶可能会 90个跨膜蛋白，包括突触信号、支架和黏附蛋白。知识鸿沟 关于𝛾-分泌酶如何维持人类神经元中健康突触的正常功能，这可以 进一步阐明AD的发病机制。 这项提议的总体目标是研究人类神经元中𝛾-分泌酶如何调节生化， 突触的形态和功能特征，包括慢性活动调节和非慢性活动调节。初步 在人类神经元中的研究证实，𝛾分泌酶是产生b-淀粉样蛋白和切割全长淀粉样蛋白所必需的 APP和Neuresin(Nrxn)蛋白。早期的研究结果表明，𝛾-分泌酶是调节密钥所必需的 突触前和突触后的蛋白质水平，以及突触的数量。 目的1描述𝛾-分泌酶在调节神经元蛋白质组成、突触形成、 以及突触传递，以更好地了解其在人类突触中的功能。我们假设𝛾- 分泌酶是维持突触完整性所必需的，通过突触前和突触后的处理 蛋白质。Aim 2将确定𝛾-分泌酶如何调节突触以应对慢性增加或 神经活动减少。由于其他蛋白水解酶具有活性依赖的调节，我们假设𝛾- 分泌酶在慢性调制后调节突触蛋白组成和突触传递。 了解𝛾-分泌酶在健康突触中的作用将有助于深入了解生理性突触 这种酶调节的过程，将促进我们对正常衰老的大脑和AD的理解 病理学。拟议的项目将在人类神经元特异性的𝛾分泌酶中建立神经元角色。 举止。进一步，它将揭示𝛾-分泌酶在调节突触活动中的作用。更深入地了解 人类神经元中的蛋白分解活性将阐明AD的候选途径和潜在的治疗靶点。

Abstract Alzheimer's Disease (AD) is the leading cause of dementia in the United States, affecting 5.7 million Americans, yet no treatments exist. Early-onset AD is most commonly caused by familial mutations of presenilins, the catalytic subunit of the protease g-secretase. Mutated 𝛾-secretase cleaves the amyloid precursor protein (APP) and releases toxic b-amyloid peptides associated with synapse loss. However, 𝛾-secretase may also contribute to synaptic dysfunction in AD through mechanisms beyond APP processing. While 𝛾-secretase contributes to AD pathology, its broader physiological roles in maintaining the proper functioning of human synapses is poorly understood. Evidence from non-neuronal cells and murine models suggest that 𝛾-secretase may process over 90 transmembrane proteins, including synaptic signaling, scaffolding, and adhesion proteins. A knowledge gap exists on how 𝛾-secretase maintains the proper functioning of healthy synapses in human neurons, which can further inform pathoetiologies of AD. The overall objective of this proposal is to examine in human neurons how 𝛾-secretase regulates biochemical, morphological, and functional features of synapses, with and without chronic activity modulation. Preliminary work in human neurons validates that 𝛾-secretase is required for b-amyloid production and cleavage of full-length APP and Neurexin (Nrxn) proteins. Early results show that 𝛾-secretase is necessary for regulating key presynaptic and postsynaptic protein levels, as well as the number of synapses. Aim 1 will characterize the role of 𝛾-secretase in regulating neuronal protein composition, synapse formation, and synaptic transmission to better understand its functions at human synapses. We hypothesize that 𝛾- secretase is needed for maintaining synaptic integrity, through the processing of presynaptic and postsynaptic proteins. Aim 2 will determine how 𝛾-secretase modulates synapses in response to chronic increases or decreases of neural activity. As other proteases have activity-dependent regulation, we hypothesize that 𝛾- secretase regulates synaptic protein composition and synaptic transmission following chronic modulation. Understanding the role of 𝛾-secretase at healthy synapses will provide insight into the physiological synaptic processes regulated by this protease, which will advance our understanding of the normal aging brain and AD pathology. The proposed project will establish the neuronal roles of 𝛾-secretase in a human neuron-specific manner. Further, it will reveal the function of 𝛾-secretase in modulating synaptic activity. Greater insight into proteolytic activity in human neurons will elucidate candidate pathways and potential therapeutic targets for AD.