Proteomic analysis of maturing adult-born hippocampal mossy fiber boutons

成年海马体中新神经元的诞生（称为神经发生）对学习和记忆至关重要， 这一过程的中断与人类神经系统疾病如阿尔茨海默病有关。率 成年海马神经发生（AHN）的变化与生理活动的变化密切相关。等活动 如增强运动或学习以及病理生理变化如癫痫，深刻地改变AHN。 因此，了解ANH神经发生如何调节神经元回路对于了解其整体 对大脑生理的影响这个问题的核心是了解成年大脑中的新生神经元如何实现 长期融合。了解AHN中调节突触整合的分子和细胞机制 可以导致在病理条件下或在治疗中用于功能改善的选择性药理学靶点。 衰老，其中成年神经发生的水平显著降低。成人的神经元祖细胞 海马齿状回产生新生颗粒（GC）细胞，当完全分化时， 内嗅皮层的突触输入，并沿沿着苔藓纤维通路发送轴突，形成突触输出 CA3锥体神经元。我们和其他人已经证明新生儿GC需要大约八周的时间 完全分化并形成成熟的突触输入和输出。该提案的主要重点是确定 GC新生苔藓纤维终扣形成突触时突触输出的分子变化 有成熟的CA3锥体细胞。我们建议使用超分辨率免疫荧光阵列断层扫描， 共轭阵列断层扫描结合电子显微镜，以描绘前和后的蛋白质组学变化， 在成熟突触建立过程中的突触后元件。我们发现，要建立一个成熟的 突触接触苔藓纤维可以1）形成新生突触或2）取代现有的苔藓纤维 纤维终扣控制现有的突触后CA3树突。的分子调控机制 这些不同的细胞过程是未知的。在这里，我们将使用阵列层析成像分析来描绘 这些突触中的蛋白质组学变化，以测试突触分子组成的假设， 在整个成熟过程中，新生神经元在成年海马中的整合是高度动态的。我们 主要有两个方面：（1）建立发育和成熟的突触前苔藓纤维的蛋白质组学图谱 在成年海马神经发生和（2）终端建立一个蛋白质组学的发展和 成熟的突触后苔藓纤维终端在成年海马神经发生。这些实验将 第一个解决复杂的蛋白质组学变化至关重要的建立新的突触输出在成年 神经发生，并将潜在地确定治疗策略的药理学靶点，以改善神经发生。 成人大脑的功能

The birth of new neurons (called neurogenesis) in the adult hippocampus is critical for learning and memory and disruption of this process is associated with human neurological disorders such as Alzheimer’s disease. Rates of adult hippocampal neurogenesis (AHN) are tightly linked with changes in physiological activity. Activities such as enhanced exercise or learning as well as pathophysiological changes such as epilepsy, profoundly alter AHN. Knowing how ANH neurogenesis regulates neuronal circuitry is therefore important for understanding its overall impact on brain physiology. Central to this issue is understanding how newborn neurons in adult brain achieve long-term integration. Understand the molecular and cellular mechanisms regulating synaptic integration in AHN could lead to selective pharmacological targets for functional improvement during pathological conditions or in aging where levels of adult neurogenesis are dramatically decreased. Neuronal progenitors in the adult hippocampal dentate gyrus give rise to newborn granule (GCs) cells that, when fully differentiated, receive synaptic inputs from entorhinal cortex and send axons along the mossy fiber pathway to form synaptic outputs with CA3 pyramidal neurons. We and others have shown that it takes about eight weeks for the newborn GCs to fully differentiate and form mature synaptic inputs and outputs. The major focus of this proposal is to determine the molecular changes in the synaptic outputs when newborn mossy fiber boutons from GC are forming synapses with mature CA3 pyramidal cells. We propose to use superresolution immunofluorescent array tomography and conjugate array tomography coupled with electron microscopy to profile the proteomic changes of the pre- and post-synaptic elements during the establishment of mature synapses. We have found that to establish a mature synaptic contact the mossy fiber can either 1) form a de novo nascent synapse or 2) replace an existing mossy fiber bouton assuming control of the existing postsynaptic CA3 dendrite. The molecular mechanisms regulating these disparate cellular processes are unknown. Here we will use array tomography analysis to profile the proteomic changes in these synapses to test the hypothesis that the synaptic molecular composition of integrating newborn neurons in adult hippocampus is highly dynamic during the entire maturation process. We have two main focuses: (1) to establish a proteomic profile of the developing and mature presynaptic mossy fiber terminal during adult hippocampal neurogenesis and (2) to establish a proteomic profile of the developing and mature postsynaptic mossy fiber terminal during adult hippocampal neurogenesis. These experiments will be the first to address the intricate proteomic changes essential for establishing new synaptic outputs during adult neurogenesis and will potentially identify a pharmacological target for therapeutic strategies to improve the function of adult brain.