神经树突线粒体炫在突触可塑性中的作用

发布时间：2018-08-27 14:07

【摘要】：树突棘是突触可塑性发生的重要场所,它的结构长时程变化被认为是记忆长期存储的结构基础。在树突棘长时程结构可塑性的细胞分子机制中,细胞器的调节处于核心地位。已有研究显示细胞核、核糖体、内质网以及内含体分别介导树突棘长时程变化所必需的基因转录、蛋白合成和受体上下膜等过程。然而,线粒体-—作为分布广泛的重要细胞器,关于它是否参与调控树突棘结构可塑性以及如何发挥信号调节作用,鲜有报道。借助于新改造的cpYFP荧光蛋白,程和平研究组在心肌细胞中发现了一种全新的单个线粒体水平的细胞生物学现象---线粒体炫。后续研究发现线粒体炫是一个多信号的复合现象,它广泛存在并可能作为信号调控多种生理病理过程。然而在神经细胞中线粒体炫的基本性质和生理功能并不清楚。我与合作者首先在培养的海马神经元中研究了线粒体炫的发放模式和基本性质;接着,我们利用化学诱导突触长时程增强的方法,发现了线粒体炫与树突棘结构可塑性的相关性。本文在此基础上,利用精确的谷氨酸解笼锁技术,详细研究了线粒体炫与树突棘结构可塑性的相关性以及线粒体炫如何在精确的时空尺度内调节突触可塑性,并探索研究了相关的信号分子通路。利用多种不同的谷氨酸解笼锁刺激模式,我们发现树突棘长时程增大均伴有邻近树突线粒体炫频率的时相性增加,而树突棘短时程增大则不会伴随邻近树突线粒体炫频率改变。不仅如此,我们还发现树突棘长时程增大幅度与刺激后邻近树突线粒体炫的发生频率正相关。机理性研究揭示,树突棘长时程增大伴随的线粒体炫频率增加依赖于CaMKII蛋白的激活,而不依赖于蛋白合成。进一步研究发现,用低浓度的尼日利亚菌素增加线粒体炫的频率,可以将谷氨酸解笼锁刺激诱发的树突棘短时程增大转变为长时程增大。后续用更精确的激光诱发线粒体炫技术,我们发现只需要诱发邻近树突单个线粒体产生线粒体炫就能促进树突棘由短时程增大转变为长时程增大。进一步,通过改变激光诱发线粒体炫发生的时间与位置,我们发现线粒体炫对于突触的长时程增大的促进作用有着精确的时间空间范围-—作用时间大约在诱发后30分钟内、作用的空间衰减常数约为2微米。此外,当用活性氧清除剂抑制突触可塑性相关的线粒体炫频率增加,可以抑制树突棘的长时程增大。综上,我们发现了一种新的调控树突棘结构可塑性的细胞生物学现象---线粒体炫。线粒体炫是树突棘结构长时程增大所必需的,并且足以将树突棘由短时程增大转变为长时程增大。我们不仅实时观测了树突棘结构可塑性过程中邻近树突线粒体炫的活动变化,还精确测量了线粒体炫调节树突棘长时程可塑性的时间、空间范围。此外,我们发现线粒体炫以调频而非调幅的方式调节树突棘增大的幅度而且这一影响可能通过局部产生活性氧来实现。
[Abstract]:Dendritic spines are important sites for synaptic plasticity, and their long-term structural changes are considered to be the structural basis for long-term memory storage. The regulation of organelles is central to the cellular and molecular mechanisms of long-term structural plasticity of dendritic spines. However, as a widely distributed and important organelle, there are few reports on whether mitochondria - - which are involved in regulating the structural plasticity of dendritic spines and how to play a signal regulatory role. With the help of the newly modified cpYFP fluorescent protein, Cheng Ping studies Mitochondrial blinding, a novel cytobiological phenomenon at the level of single mitochondria, has been found in cardiomyocytes. Subsequent studies have found that mitochondrial blinding is a multi-signal complex phenomenon, which is widespread and may serve as a signal to regulate a variety of physiological and pathological processes. However, the basic properties and physiology of mitochondrial blinding in nerve cells. The function of mitochondrial blinding is not clear. First, we studied the release patterns and basic properties of mitochondrial blinding in cultured hippocampal neurons. Then, we found the correlation between mitochondrial blinding and structural plasticity of dendritic spines by chemically induced long-term potentiation of synapses. The correlation between mitochondrial dazzling and structural plasticity of dendritic spines and how mitochondrial dazzling regulates synaptic plasticity at precise spatial and temporal scales are studied in detail, and related signaling pathways are explored. In addition, we also found that the amplitude of long-term increase of dendritic spines was positively correlated with the frequency of mitochondrial blinding in adjacent dendrites after stimulation. The increase in mitochondrial blinding frequency depends on the activation of CaMKII protein rather than on protein synthesis. Further studies have shown that increasing the frequency of mitochondrial blinding with low concentrations of Nigeria bacteriocin can transform the short-term increase of dendritic spines induced by glutamate unlocking stimulation into the long-term increase. In addition, by changing the time and location of laser-induced mitochondrial blinding, we found that mitochondrial blinding had a precise effect on long-term synaptic growth. The time-space range - - action time is about 30 minutes after induction, and the spatial attenuation constant of action is about 2 microns. In addition, when reactive oxygen species scavengers inhibit synaptic plasticity-related mitochondrial blinding frequencies increase, the long-term increase of dendritic spines can be inhibited. Mitochondrial blinding is necessary for long-term enlargement of dendritic spines and is sufficient to transform dendritic spines from short-term to long-term enlargement. In addition, we found that mitochondrial flare modulates the amplitude of dendritic spine enlargement in a frequency-modulated rather than amplitude-modulated manner, and this effect may be achieved by local production of reactive oxygen species.
【学位授予单位】：中国科学技术大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：Q42

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