The Role of Afadin in Coordinating Cell Adhesion Molecules during Synaptogenesis

Afadin 在突触发生过程中协调细胞粘附分子的作用

• 批准号: 7846868
• 负责人: GERARD MJ BEAUDOIN III
• 金额: $ 5.38万
• 依托单位: UNIVERSITY OF CALIFORNIA, SAN FRANCISCO
• 依托单位国家: 美国
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2011-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7846868
• 关键词: Adherens Junction; Adhesions; Affect; Axon; Binding; Brain region; Cadherins; Cell Adhesion Molecules; Cell Surface Receptors; Cells; Dendrites; Epithelial Cells; Family; In Vitro; Intercellular Adhesion Molecules; Lead; Link; Mediating; Molecular; Nervous System Physiology; Neurons; Neurotransmitters; Phenotype; Play; Protein Isoforms; Proteins; Recruitment Activity; Research; Role; Signal Transduction; Specificity; Synapses; Synaptic Membranes; afadin; alpha catenin; base; interest; mutant; nectin; neural circuit; neurotransmitter release; postsynaptic; presynaptic; synaptogenesis

DESCRIPTION (provided by applicant): Synaptic junction formation is initiated between axons and dendrites by intercellular adhesion molecules, which through bound intracellular effectors, nucleate the reciprocal recruitment of proteins required for presynaptic neurotransmitter release and postsynaptic neurotransmitter reception. Junctions analogous to adherens junctions are formed during synaptogenesis. Cadherins are intercellular adhesion molecules central to the formation of adherens junctions in epithelial cells. Studies on cadherin function in neurons have demonstrated a role for cadherins and their associated catenins in regulating synapse number and maturation of both pre- and post-synaptic membranes. Expression studies have found that cadherin isoforms are not expressed ubiquitously, but are localized to distinct neural circuits, suggesting that cadherins may play a role in synaptic specificity. Based upon studies in epithelial cells, adherens junctions are thought to be initiated by nectin interaction in trans followed by cadherin recruitment. Nectins rely upon their interaction with the PDZ domain of afadin to recruit and activate cadherins. Through this same PDZ domain, afadin can bind other cell surface receptors, which have an established role in synaptogenesis. I am proposing to examine the role of afadin-mediated cell surface receptor's association with cadherins on synaptogenesis, by examining the affect of loss of afadin expression. Loss of this molecular link will likely block cadherin association with several cell surface receptor families. As loss of afadin in cultured epithelial cells has been shown to lead to a loss of nectin and cadherin adhesion, we expect a severe reduction in synapse formation and/or stabilization. As previous analysis has not satisfactorily demonstrated how afadin associates with alpha-catenin and p120-catenin, additional analysis will be directed at examining the domains of afadin that binds these catenins. I will examine the role of afadin association with these catenins, by determining the ability of these mutants to rescue the afadin null phenotype in vitro. Finally, the effect of loss of afadin on signaling initiated by these other cell surface receptors will be determined. Proper nervous system functioning requires the ordered synaptic connection of disparate brain regions between seemingly unrelated cells. While much research has documented the molecules required for guiding axons to the right brain regions, we are interested in determining how axons then connect with the proper neuron and on the proper part of the neuron. This proposal is studying the associations between different classes of adhesion proteins and the role of this association in creating and modifying synapses, which is likely to play a role in generating synaptic specificity.

描述（由申请人提供）：突触连接的形成由细胞间粘附分子在轴突和树突之间启动，细胞间粘附分子通过结合的细胞内效应物，使突触前神经递质释放和突触后神经递质接收所需的蛋白质的相互募集成核。类似于粘附连接的连接在突触发生过程中形成。钙粘蛋白是细胞间粘附分子，对上皮细胞中粘附连接的形成至关重要。对神经元中钙粘蛋白功能的研究已经证明了钙粘蛋白及其相关的连环蛋白在调节突触数量和突触前膜和突触后膜的成熟中的作用。表达研究发现，钙粘蛋白亚型并不是普遍表达的，而是定位于不同的神经回路，这表明钙粘蛋白可能在突触特异性中发挥作用。基于在上皮细胞中的研究，粘附连接被认为是由反式连接素相互作用，然后是钙粘蛋白募集启动的。连接蛋白依赖于它们与afadin的PDZ结构域的相互作用来募集和激活钙粘蛋白。通过这个相同的PDZ结构域，afadin可以结合其他细胞表面受体，这些受体在突触发生中具有确定的作用。我建议通过研究afadin表达缺失的影响，来研究afadin介导的细胞表面受体与钙粘蛋白在突触发生中的作用。这种分子连接的丧失可能会阻断钙粘蛋白与几种细胞表面受体家族的结合。由于在培养的上皮细胞中afadin的损失已被证明会导致nectin和钙粘蛋白粘附的损失，我们预计突触形成和/或稳定性严重减少。由于以前的分析没有令人满意地证明阿法丁如何与α-连环蛋白和p120-连环蛋白结合，因此将进行进一步的分析，以检查结合这些连环蛋白的阿法丁结构域。我将通过确定这些突变体在体外拯救afadin空表型的能力，来研究afadin与这些连环蛋白的关联作用。最后，将确定afadin缺失对由这些其他细胞表面受体引发的信号传导的影响。 正常的神经系统功能需要看似无关的细胞之间的不同大脑区域的有序突触连接。虽然许多研究已经记录了引导轴突到达右脑区域所需的分子，但我们感兴趣的是确定轴突如何与适当的神经元连接，并连接到神经元的适当部分。该提案正在研究不同类别的粘附蛋白之间的关联以及这种关联在创建和修改突触中的作用，这可能在产生突触特异性方面发挥作用。

项目成果

Afadin, a Ras/Rap effector that controls cadherin function, promotes spine and excitatory synapse density in the hippocampus.

• DOI: 10.1523/jneurosci.4565-11.2012
• 发表时间: 2012-01-04
• 期刊: The Journal of neuroscience : the official journal of the Society for Neuroscience
• 作者: Beaudoin GM 3rd;Schofield CM;Nuwal T;Zang K;Ullian EM;Huang B;Reichardt LF
• 通讯作者: Reichardt LF