Molecular Mechanisms of Dendrite Formation During Embryonic Neuronal Development

胚胎神经元发育过程中树突形成的分子机制

• 批准号: 9191378
• 负责人: Maya Shelly
• 金额: $ 34.35万
• 依托单位: STATE UNIVERSITY NEW YORK STONY BROOK
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-01-15 至 2018-12-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9191378
• 关键词: Affect; Architecture; Axon; Biochemistry; Brain; Cell Polarity; Cells; Cyclic AMP; Cyclic GMP; Cyclic GMP-Dependent Protein Kinases; Dendrites; Development; Developmental Process; Disease; Down-Regulation; Electroporation; Embryo; Embryonic Development; Engineering; Enzymes; Event; Fluorescence Resonance Energy Transfer; Genetic; Growth; Hippocampus (Brain); Image; In Vitro; Instruction; Intracellular Second Messenger; Lead; Life; Location; Measures; Mediating; Mental Retardation; Microscopy; Modeling; Molecular; Morphology; Mus; Neurites; Neuroglia; Neurons; Newborn Infant; Nitric Oxide Synthase; Output; Pathway interactions; Pattern; Play; Preparation; Process; Regulation; Rodent; Role; Second Messenger Systems; Serum; Signal Pathway; Signal Transduction; Soluble Guanylate Cyclase; Specificity; Structure of superior cervical ganglion; Subfamily lentivirinae; Synapses; Testing; Therapeutic; Time; Translating; Undifferentiated; autism spectrum disorder; axon growth; base; bone; clinical application; experience; extracellular; genetic manipulation; in utero; in vivo; migration; neuron development; neuropathology; phosphoric diester hydrolase; plexin; progenitor; protein complex; public health relevance; receptor; scaffold; small hairpin RNA

DESCRIPTION (provided by applicant): The formation and directed growth of axon and dendrite, migration to a desired location in the developing brain, maturation of axonal and dendritic arbors, and establishment of proper synaptic connections are essential processes during embryonic neuronal development. With these overlapping and well coordinated developmental processes, the development of a neuronal cell begins with a process in which the neuron establishes axon and dendrite identities, an architecture that is critical for the input/output functions of the neuron. In the last decade, much effort has been made towards the elucidation of the molecular and cellular mechanisms that control axon initiation and outgrowth1-23. The morphological and functional differentiation of dendrites persists throughout life and underlies experience-dependent plasticity. Moreover, aberrations affecting dendrite development and maturation play key role in severe disorders such as mental retardation and autism spectrum disorders. The identification of the signaling pathways that determine the early events in dendrite development is of great importance for efforts to translate these mechanisms into clinical application. Despite this, the molecular mechanisms that establish the dendritic identity during embryonic development remain largely unexplored. The current mechanistic paradigm for neuronal development is that axon differentiation of one neurite is accompanied by dendrite formation in other neurites, suggesting that dendrite development may represent a default pathway. This proposal offers an alternative hypothesis to "dendrites by default" and proposes a 'three-step' model of axon/dendrite establishment that is driven by opposite changes in the activity of the second messengers cAMP and cGMP. First, local elevation of cAMP-activity in a single undifferentiated neurite determines its axon fate17,19. Second, a negative signal propagating from the forming axon results in inhibition of axon formation in all other neurites of the same cell3,18-20. Last, localized cGMP-specific signaling events19,25,26 determine the dendrite fate of these neurites. In this proposal we identify cGMP-specific dendrite promoting events. We propose three specific aims to test our hypothesis both in vitro and in vivo. First, we directly determine cGMP-induced dendrite formation in cultured rodent sympathetic neurons44,45 in which dendrite differentiation is an inducible process. Next, we examine possible dendrite-specific determinants downstream and upstream of cGMP signaling. Last, we examine cGMP-dependent promotion of dendrite development in cortical progenitors in the developing embryonic brain in vivo. In these studies we employ a wide range of approaches that combine embryonic genetic manipulation using in utero electroporation, mouse genetics, biochemistry, material engineering, time-lapse microscopy and fluorescence resonance energy transfer (FRET) imaging. The cGMP- specific events that determine the dendritic fate, as identified in this study, are directly implicated in the neuropathology of autism spectrum disorders.

描述（由申请人提供）：轴突和树突的形成和定向生长、迁移到发育中的脑中的期望位置、轴突和树突的成熟以及正确的突触连接的建立是胚胎神经元发育期间的基本过程。通过这些重叠且协调良好的发育过程，神经元细胞的发育始于神经元建立轴突和树突身份的过程，这一体系结构对于神经元的输入/输出功能至关重要。在过去的十年中，已经作出了很大的努力，对控制轴突的起始和outgrowth 1 -23的分子和细胞机制的阐明。树突的形态和功能分化在整个生命过程中持续存在，并成为经验依赖性可塑性的基础。此外，影响树突发育和成熟的畸变在严重疾病如精神发育迟滞和自闭症谱系障碍中起关键作用。确定决定树突发育早期事件的信号通路对于将这些机制转化为临床应用具有重要意义。尽管如此，在胚胎发育过程中建立树突身份的分子机制仍然在很大程度上未被探索。目前神经元发育的机制范式是一个神经突的轴突分化伴随着其他神经突中的树突形成，这表明树突发育可能代表默认途径。这一提议提供了一个替代假设，以“树突默认”，并提出了一个“三步”模型的轴突/树突的建立，是由第二信使cAMP和cGMP的活性相反的变化。首先，在单个未分化的神经突中cAMP活性的局部升高决定其轴突命运17，19。第二，从形成轴突传播的负信号导致同一细胞的所有其他神经突中轴突形成的抑制3，18-20。最后，局部cGMP特异性信号事件19，25，26决定了这些神经突的树突命运。在这个建议中，我们确定cGMP特异性树突促进事件。我们提出了三个具体的目标来测试我们的假设在体外和体内。首先，我们直接确定cGMP诱导的树突形成在培养的啮齿动物交感神经元44，45，其中树突分化是一个诱导过程。接下来，我们研究了cGMP信号传导的下游和上游可能的树突特异性决定因素。最后，我们研究了cGMP依赖的促进树突发育的皮质祖细胞在体内发育的胚胎脑。在这些研究中，我们采用了广泛的方法，结合联合收割机胚胎遗传操作使用子宫内电穿孔，小鼠遗传学，生物化学，材料工程，延时显微镜和荧光共振能量转移（FRET）成像。如本研究中所鉴定的，决定树突命运的cGMP特异性事件直接涉及自闭症谱系障碍的神经病理学。