Distinct role of Neurabin and Spinophilin in Synaptic Transmission and Plasticity

摘要： 大量证据表明，突触功能严重受损。 阿尔茨海默病和其他神经退行性疾病，导致认知缺陷 即使在这些疾病的早期阶段也是如此。众所周知，蛋白质 磷酸酶-1(PP1)在突触功能中起着关键作用。然而，我们的初步调查 数据表明，至少有两个突触PP1群体可以施加 突触传递的差异功能。我们的近期目标是阐明 这两种突触PP1的不同靶向和信号机制 人口。我们的长期目标是将这些知识应用于理解如何 突触功能中PP1信号的损伤在疾病中是可以预防的。 我们最新获得的初步数据表明，可能有两个不同的PP1池 分别以神经肽和刺激素为靶标，在突触中具有相反的功能 在长期抑郁(LTD)中起着不同的作用。在这份提案中， 我们假设神经节苷脂和刺激素可以对基底细胞起相反的作用。 突触传递(目标1)通过微靶向其货物(PP1)至不同的 突触内的微室，作用于不同的底物，即Ser657 PKC？(间接位于GluR2上的Ser880)和Ser831上的Ser831。在……里面 对LTD刺激的反应(AIM2)，我们建议测试我们的假设，即Neurabin将 流量到PSD部分使GSK3？去磷酸化，导致突触抑制 亲刺素在这一过程中不起作用。神经氨酸结合蛋白和神经肽的关键结构域 在这两个目的中，亲刺蛋白调节它们不同的作用将通过一种 电生理记录与最新分子生物学的结合 替换法。在Aim3中，我们将假设神经肽，但不是刺激性蛋白， 在LTP的表达中起到负面作用。我们建议确定磷酸化 长时程增强刺激克服抑制效应的神经肽机制 正常LTP发生的NRB/PP1复合体。最后，我们还将检验假设 NRB/PP1修饰CaMKII和/或GSK3β，使其在LTP中发挥抑制作用。 从这些研究获得的结果将提供更好的理解 (1)调节PP1与不同结合蛋白相互作用的生物学机制 不同底物特异性，(2)神经肽关键功能的结构基础 和亲刺素在突触功能中的作用；以及(3)提供对治疗 神经退行性疾病患者的认知缺陷。

Abstract: Considerable evidence suggests that synaptic function is severely compromised in Alzheimer's disease and other neurodegenerative diseases, leading to cognitive defects even during the early stages of these diseases. It is well known that protein phosphatase-1 (PP1) plays a critical role in synaptic function. However, our preliminary data indicates that there are at least two synaptic PP1 populations which can exert differential functions on synaptic transmission. Our immediate goal is to elucidate the differential targeting and signaling mechanisms underlying these two synaptic PP1 populations. Our longer-term goal is to apply this knowledge in understanding how impairment of PP1 signaling in synaptic function can be prevented in diseases. Our newly acquired preliminary data suggest that two distinct pools of PP1, probably targeted respectively by neurabin and spinophilin, have opposite functions in synaptic transmission and play differential roles in long term depression (LTD). In this proposal, we hypothesize that neurabin and spinophilin can exert their opposite effects on basal synaptic transmission (Aim 1) through micro-targeting their cargoes (PP1) to distinct micro-compartments within synapses, acting on different substrates, i.e, Ser657 on PKC¿ (and indirectly on Ser880 on GluR2) and Ser831 on GluR1, respectively. In response to LTD stimulus (Aim2), we propose to test our hypothesis that neurabin will traffic to PSD fraction to dephosphorylate GSK3¿, leading to synaptic depression while spinophilin does not play a role in this process. Critical domains on neurabin and spinophilin mediating their distinct effects will be elucidated in these two aims by a combination of electrophysiological recording and the state-of-the-art molecular replacement approach. In Aim3, we will hypothesize that neurabin, but not spinophilin, plays a negative role in LTP expression. We propose to determine the phosphorylation mechanism on neurabin by which LTP stimulus uses to overcome the inhibitory effects of Nrb/PP1 complex for normal LTP to occur. Finally we will also test the hypotheses that Nrb/PP1 modifies CaMKII and/or GSK3¿ for its inhibitory function in LTP. The results obtained from these studies will provide a better understanding of biological mechanisms that (1) regulate PP1 interaction with different binding proteins for differential substrate specificity, (2) structural basis for the critical functions of neurabin and spinophilin in synaptic functions; and (3) provide insights into therapeutic cures for the cognitive defects in patients with neuro-degenerative diseases.