Identifying molecules that modulate auxiliary factors of AMPA receptors

产品说明：认知、行为、神经回路的活动、突触可塑性和神经元存活与离子型谷氨酸受体（iGluR）的配体门控离子通道的正常功能有关。AMPA-type iGluRs（AMPA-Rs）参与哺乳动物脑内大多数兴奋性突触传递，其功能障碍涉及多种神经和精神疾病。例如，AMPA-R的正调节剂减轻重度抑郁症（MDD）症状，突触AMPA-R在阿尔茨海默病的小鼠模型中减少，并且结合AMPA-R的自身抗体引起拉斯穆森脑炎和边缘系统脑炎的子集。特别是，靶向AMPA-R的MDD的现有药物具有局限性，并且需要机械上新颖的AMPA-R调节剂用于治疗开发和理解疾病机制。AMPA-R是由什么组成的蛋白质复合物？然后呢？亚单位。什么？亚基被称为GluA 1 -4，并构建配体门控离子通道孔的四聚体核心，而？亚基有助于受体的功能调节，而不是孔结构的一部分。什么？亚基也被称为辅助因子，并且可以被认为是自然界在进化过程中产生的一组AMPA-R的内源性调节剂。辅助因子调节AMPA-Rs介导的突触后反应的大小和形状。从机制上讲，调节运输涉及改变突触处AMPA-R的数量和迁移率，而改变离子通道的门控动力学将直接改变膜去极化的时间过程。通过改变影响突触后电流的交通和门控参数，辅助亚基影响同时检测和树突整合。最终，这种突触调制被认为会影响神经回路和行为的活动。因此，可以想象，用AMPA-R的内源性调节剂进行干预将具有强烈的生理效应。然而，目前尚不清楚是否？iGluR的亚基将是操纵配体门控离子通道功能的有效药物靶标。为了验证这个假设， 我们计划将联合收割机HTS与我们开发的新的基于细胞的测定相结合，以筛选特异性作用于AMPA-R的辅助因子依赖性调节的化合物。针对AMPA-Rs开发的传统药物主要针对孔隙形成？亚单位。如果从我们提出的筛选中鉴定出新的探针，iGluR的辅助因子将成为药物开发的新靶点。值得注意的是，？钾通道中的亚基已经是确定的药物靶点。新的内源性AMPA-R辅助因子不断被发现，提供了更广泛的分子靶点。每个辅助因子都有不同的表达模式，表明靶向药物将具有细胞类型特异性作用。使用所提出的HTS筛选方法，通过与辅助亚基的相互作用来调节AMPA-R活性的化合物的鉴定将为开发针对AMPA-R的新药，特别是针对MDD的新药提供范式转变。

DESCRIPTION: Cognition, behavior, activity of neural circuits, synaptic plasticity, and neuronal survival relate to proper functioning of ligand gated ion channels of the ionotropic glutamate receptors (iGluRs). AMPA-type iGluRs (AMPA-Rs) contribute to the majority of excitatory synaptic transmission in mammalian brain and their dysfunction involves a variety of neurological and psychiatric disorders. For example, positive modulators of AMPA-Rs alleviate major depression disorder (MDD) symptoms, synaptic AMPA-Rs are reduced in mouse models of Alzheimer's disease, and auto-antibodies that bind to AMPA-Rs cause Rasmussen's encephalitis and a subset of limbic encephalitis. In particular, existing drugs for MDD targeting AMPA-Rs have limitations and mechanistically novel AMPA-R modulators are needed for therapeutic development and understanding disease mechanism. AMPA-Rs are protein complexes made of ? and ? subunits. The ? subunits are known as GluA1-4 and construct the tetrameric core of the ligand gated ion channel pore, whereas ? subunits contribute to functional modulation of the receptors without being part of the pore structure. The ? subunits are also known as the auxiliary factors and may be regarded as a set of endogenous modulators of AMPA-Rs developed by nature during evolution. Auxiliary factors modulate the magnitude and shape of postsynaptic responses mediated by AMPA-Rs. Mechanistically, modulating trafficking relates to changing the number and mobility of AMPA-Rs at synapses, whereas altering the gating kinetics of the ion channel will directly modify the time course of membrane depolarization. By changing trafficking and gating parameters influencing postsynaptic currents, auxiliary subunits impact coincident detection and dendritic integration. Ultimately such synaptic modulation is believed to affect the activity of neural circuits and behavior. It is thus conceivable that intervening with endogenous modulators of AMPA-Rs would have strong physiological effects. It is unclear, however, whether ? subunits of iGluR would be effective drug targets for manipulating ligand gated ion channel function. To test this hypothesis, we plan to combine HTS with new cell based assays we developed in order to screen for chemical compounds that specifically act on auxiliary factor dependent modulation of AMPA-Rs. Conventional drugs developed against AMPA-Rs focus on pore forming ? subunits. If new probes are identified from our proposed screening, auxiliary factors of iGluR will become a mechanistically new target for drug development. It is important to note that ? subunits in potassium channels are already established drug targets. New endogenous auxiliary factors of AMPA-Rs are continuously being identified, providing broader spectrum of molecular targets. Each auxiliary factor has distinct expression patters, indicating that targeted drugs will have cel-type specific effects. Using the proposed HTS screening approach, the identification of compounds that modulate AMPA-R activity through interaction with the auxiliary subunits will provide a paradigm shift in developing new drugs against AMPA-Rs, in particular for MDD.