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类型 基础研究 预答辩日期 2018-03-09
开始(开题)日期 2016-05-25 论文结束日期 2017-12-18
地点 李文正楼北225 论文选题来源 国家社科规划、基金项目     论文字数 5.1 (万字)
题目 神经突促生长因子NGPF2在稳态突触缩放过程中的作用及机制研究
主题词 稳态突触缩放,神经突促生长因子,间变性淋巴瘤激酶,LIM激酶,丝切蛋白
摘要 稳态突触可塑性是中枢神经系统中一类以负反馈调控的方式维持神经系统功能稳定的突触可塑性。稳态突触缩放是稳态突触可塑性中研究最为广泛的形式之一,即当神经网络活动受到抑制或得到增强时,神经网络以补偿的方式改变突触能效相应地增强或抑制网络活动,以维持整个神经网络的兴奋性在一定的生理水平。例如在视觉皮层发育的关键时期,稳态突触缩放可调控视皮层神经元之间的联系,进而逐渐形成稳定的视觉神经网络。虽然前人对稳态突触可塑性的研究已经开展了二十几年,但对其内在的分子机制仍知之甚少。众所周知,细胞外信号分子,如生长因子、细胞因子和基质蛋白等作为细胞信号转导中的重要组成部分,参与调控神经网络的各项功能。然而,目前已知的参与稳态突触缩放的细胞外信号分子只有BDNF和TNFα,是否存在其他细胞外信号分子参与了稳态突触缩放还需要深入研究。 在本课题中,我们利用钠离子通道阻断剂河豚毒素TTX剥夺原代培养的皮层神经元活动作为研究稳态突触缩放的模型。我们发现短时程抑制神经元活动后,会有大量的神经突促生长因子NGPF2分泌到培养基中,暗示NGPF2可能参与了稳态突触缩放的调控。通过生物化学、分子生物学、免疫荧光和电生理记录等一系列方法对NGPF2的生理功能以及参与稳态突触缩放的内在分子机制展开研究,我们获得了以下发现:首先,NGPF2能够促进神经元树突棘的成熟、AMPA受体在突触膜表面的累积,增强突触传递;其次,TTX诱导NGPF2的大量表达受到脆性X智力低下蛋白FMRP的调控;此外,我们还发现NGPF2上调表达是突触缩放过程的启动阶段的必要条件,细胞外NGPF2通过其受体间变性淋巴瘤激酶ALK激活细胞内下游的LIMK/Cofilin信号通路,使得丝切蛋白Cofilin磷酸化水平显著升高,抑制Cofilin活性,进而促进谷氨酸受体在突触后聚集,增强突触传递,实现突触放大(up-scaling)。 本研究不仅发现了一种除BDNF和TNFα之外的另一种细胞因子——NGPF2参与了稳态突触缩放,而且揭示了NGPF2的生理功能以及参与调控突触放大的分子机制,为后续深入研究稳态突触可塑性以及NGPF2在神经系统中的功能提供了理论基础。
英文题目 The Function and Mechanism of Neurite Growth-promoting Factor 2 in Homeostatic Synaptic Scaling
英文主题词 Homeostatic Synaptic Scaling, Neurite Growth-promoting Factor 2, Anaplasticlymphoma Kinase, LIM Kinase, Cofilin
英文摘要 Homeostatic synaptic plasticity is a form of negative regulation to maintain the network stability in the central nervous system. Synaptic scaling is the most extensively studied form of homeostatic synaptic plasticity. In this system, manipulations that reduce or elevate the activity of the neuronal firing induce robust compensatory changes in the strength of synapses to elevate or weaken the neuronal activity that restore the neuronal network firing rate within a physiological range. During the critical period of visual cortex development, synpatic scaling regulates the visual neuronal connections to promote proper visual network fomation. Although homeostatic synaptic plasticity has been studied for more than two decades, the molecular mechanism underlying this process is little known. Extracellular signaling molecules, such as growth factors, cytokines and matrix proteins have important roles in signal transduction and finally to modify the functions of networks. However, up to present, only two extracellular molecules, BDNF and TNFα, have been reported as regulators of homeostatic synaptic scaling. Whether there are other extracellular signaling molecules that may participate in the regulation of homeostatic synaptic plasticity requires further investigation. In this study, we utilized a sodium channel blocker, tetrodotoxin (TTX) to deprive the cultured primary cortical neuronal activity to explore the homeostatic synaptic scaling. We found that large amount of neurite growth-promoting factor 2 (NGPF2) was secreted into the medium after exposure to TTX for short time. So, we hypothesized that NGPF2 may play an important role in homeostatic synaptic scaling. We further explored the physiological function and underlying mechanism reglating homeostatic synaptic scaling through a serious of assays, including biochemistry,molecular biology, imaging and electrophysiology, first, we found that NGPF2 can promote the dendritic spine maturation and the strength of synapstic transmission. Second, the TTX-induced NGPF2 expression is regulated by fragile X mental retardation protein (FMRP). Third, we show that NGPF2 is critical for the initiation of homeostatic synaptic scaling, by interacting with anaplasticlymphoma kinase (ALK) thus subsequently activate downstream signaling to regulate synaptic up-scaling. Last, we reveal that NGPF2/ALK interaction can activate the LIMK/Cofilin pathway, resulted in an increase of Cofilin phosphorylation and ultimately regulate synaptic up-scaling. Our findings not only identified a new growth factor, other than BDNF and TNFα, that plays an important role in the regulation of homeostatic synaptic scaling, but also reveal the physiological role of NGPF2 and the underlying molecular mechanism that regulates homeostatic synaptic scaling. This study elucidates the importance of NGPF2 in the regulation of homeostatic synaptic scaling, which provides a theoretical basis for further study of homeostatic synaptic plasticity and functions of NGPF2 in the nervous system.
学术讨论
主办单位时间地点报告人报告主题
东大生科院 2014.03 李文正楼213 蒲慕明 大脑的可塑性:从突触到认知
东大生科院 2015.10 李文正楼213 胡海岚 情绪和社会行为的神经基础
东大生科院 2016.04 李文正楼213 许执恒 神经干细胞发育与小颅畸形
东大生科院 2016.12 李文正楼213 寿天德 Stream-preferred modulation of feedback projections from the higher areas to lower areas in the visual cortex
东大生科院 2014.10 李文正楼225 贺桂琴 The role of HDAC4 in homeostatic synaptic plasticity
东大生科院 2015.12 李文正楼225 贺桂琴 Neurite growth-promoting factor 2 promotes synaptic strength and mediates homeostatic synaptic scaling
东大生科院 2016.11 李文正楼225 贺桂琴 Anti-Aβ42 camel heavy-chain variable domain counteracts Aβ42-induced pathological effects
东大生科院 2017.5 李文正楼225 贺桂琴 Cdk7 Is Required for Activity-Dependent Neuronal Gene Expression, Long-Lasting Synaptic Plasticity and Long-Term Memory
     
学术会议
会议名称时间地点本人报告本人报告题目
中国神经科学学会第十一届全国会议 2015.09 浙江乌镇
Neuroscience 2016,the 46th annual meeting of Society for Neuroscience(SfN) 2016.11 San Diego,CA
东大生科院 2016.05 李文正楼213 The function and mechanism of NGPF2 in homeostatic synaptic scaling
东大生科院 2017.08 李文正楼213 Cdk7 Is Required for Activity-Dependent Neuronal Gene Expression, Long-Lasting Synaptic Plasticity and Long-Term Memory
     
代表作
论文名称
Cdk7 Is Required for Activity-Dependent Neuronal Gene Expression, Long-Lasting Synaptic Plasticity a
 
答辩委员会组成信息
姓名职称导师类别工作单位是否主席备注
谢维 正高 教授 博导 东南大学
陆巍 正高 教授 博导 东南大学
朱景宁 正高 教授 博导 南京大学
刘妍 正高 教授 博导 南京医科大学
潘玉峰 正高 教授 博导 东南大学
      
答辩秘书信息
姓名职称工作单位备注
吕卉卉 其他 工程师 东南大学