The role of Fat3 in amacrine cell dendrite development.

Fat3 在无长突细胞树突发育中的作用。

基本信息

批准号：
8353135
负责人：
Lisa Goodrich
金额：
$ 21.13万
依托单位：
HARVARD MEDICAL SCHOOL
依托单位国家：
美国
项目类别：
财政年份：
2012
资助国家：
美国
起止时间：
2012-08-01 至 2014-07-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8353135
关键词：
Address Adopted Amacrine Cells American Apical Automobile Driving Axon Back Behavior Binding Proteins Biochemistry Biological Assay Blindness Brain Cadherins Cataloging Catalogs Cell Surface Receptors Cells DNA Sequence Rearrangement Dendrites Development Electroporation Ensure Environment Event Eye Family Fatty acid glycerol esters Foundations Future Glean Golgi Apparatus Human Image Imaging Techniques In Vitro Individual Inner Plexiform Layer Interneurons Knowledge Label Left Life Ligands Link Location Mediating Molecular Morphogenesis Morphology Movement Mus Neurites Neurons Neuropil Play Population Positioning Attribute Process Proteins Reading Recruitment Activity Resolution Rest Retina Retinal Role Sensory Series Signal Pathway Signal Transduction Staging Stereotyping Synapses System Testing Tissues To specify Vision Visual Work Yeasts axon guidance blind design extracellular improved in vivo member mutant neural prosthesis neuronal cell body novel research study response restoration vasodilator-stimulated phosphoprotein yeast two hybrid system

项目摘要

DESCRIPTION (provided by applicant): Brain function depends on the flow of information through precisely wired connections between axons and dendrites. Neurons within a circuit can vary widely in the number and arrangement of their dendrites, with some neurons extending only one primary dendrite into a well-defined neuropil and others developing multiple dendrites that extend symmetrically about the cell body. However, in contrast to excellent progress in uncovering mechanisms of axon specification and guidance, relatively little is known about the initial specification and outgrowth of dendrites. In vitro studies suggest that neurons initially extend multipotent neurites, one of which becomes an axon, leaving the remainder to differentiate as dendrites. These results suggest that many aspects of dendrite differentiation are intrinsically regulated. However, in vivo, dendrite development must also be coordinated with the surrounding tissue, such that dendrites are properly positioned to form the appropriate synaptic connections. How extracellular signals induce the intracellular rearrangements that drive the initial specification and subsequent morphogenesis of dendrites is unknown. In the past, this issue has been hard to tackle due to the lack of a suitable assay and the absence of any obvious molecular players. We have been addressing these problems by establishing a system for studying dendrite development in the amacrine cells of the retina. Amacrine cells are typically unipolar, extending a single apical dendrite into a discrete synaptic layer called the inner plexiform layer (IPL). However, in mice lacking the atypical cadherin Fat3, amacrine cells develop a second dendritic arbor that points away from the IPL. Since Fat3 is a cell surface receptor, these results suggest that Fat3 acts by inducing migrating precursors to retract their trailing processes in response to a signal encountered in the IPL. How Fat3 signaling ultimately promotes development of the apical dendrite is a mystery, with no known effectors or ligands. To establish a baseline of knowledge for more detailed analysis of dendrite development, two exploratory studies will be performed. First, we will develop a live imaging assay that can be used to describe the dynamic changes in neurite behavior and Golgi localization that occur as the leading process becomes a dendrite and the trailing process is retracted. Second, to work our way inside the dendrite, we will search for downstream effectors for Fat3, both by testing likely candidate proteins and by performing an unbiased screen for proteins that interact with the Fat3 intracellular domain. Together, these studies will define the salient events of dendrite specification and elucidate the signaling events that occur downstream of Fat3. PUBLIC HEALTH RELEVANCE: Our sense of vision is mediated by precisely organized circuits in the retina, a sensory tissue located at the back of the eye. Millions of Americans are blind and unable to participate in daily activities such as reading and driving. Understanding how visual circuits are wired during development will improve efforts to identify the causes of blindness and eventually design neural prostheses for the restoration of sight.

描述（由申请人提供）：大脑功能取决于轴突和树突之间通过精确有线连接的信息流。回路内的神经元在树突的数量和排列上差异很大，一些神经元仅将一个初级树突延伸到明确的神经毡中，而另一些神经元则发育出多个关于细胞体对称延伸的树突。然而，与揭示轴突规范和引导机制方面的巨大进展相比，人们对树突的初始规范和生长知之甚少。体外研究表明，神经元最初延伸多能神经突，其中一个成为轴突，其余部分分化为树突。这些结果表明树突分化的许多方面都受到内在调节。然而，在体内，树突发育还必须与周围组织协调，以便树突正确定位以形成适当的突触连接。细胞外信号如何诱导细胞内重排，从而驱动树突的初始规格和随后的形态发生，目前尚不清楚。过去，由于缺乏合适的检测方法和任何明显的分子参与者，这个问题很难解决。我们一直在通过建立研究视网膜无长突细胞树突发育的系统来解决这些问题。无长突细胞通常是单极的，将单个顶端树突延伸到称为内丛状层（IPL）的离散突触层。然而，在缺乏非典型钙粘蛋白 Fat3 的小鼠中，无长突细胞会发育出第二个远离 IPL 的树突状乔木。由于 Fat3 是一种细胞表面受体，这些结果表明 Fat3 通过诱导迁移前体收缩其尾随过程来响应 IPL 中遇到的信号而发挥作用。 Fat3 信号如何最终促进顶端树突的发育是一个谜，目前还没有已知的效应子或配体。为了建立更详细的树突发育分析的知识基线，将进行两项探索性研究。首先，我们将开发一种实时成像测定，可用于描述当前导过程变成树突并且尾随过程缩回时发生的神经突行为和高尔基体定位的动态变化。其次，为了在树突内部进行研究，我们将通过测试可能的候选蛋白质以及对与 Fat3 胞内结构域相互作用的蛋白质进行公正的筛选来寻找 Fat3 的下游效应子。这些研究将共同定义树突规范的显着事件，并阐明 Fat3 下游发生的信号事件。公共健康相关性：我们的视觉是由视网膜（位于眼睛后部的感觉组织）中精确组织的电路调节的。数百万美国人失明，无法参与阅读和驾驶等日常活动。了解视觉回路在发育过程中如何连接将有助于识别失明原因，并最终设计用于恢复视力的神经假体。