Structural landscape of photoreceptor synapses

项目总结 视杆和视锥感光器对于我们的视力来说是不可或缺的。他们的死亡或功能障碍是一个潜在的 导致绝大多数视网膜失明的原因。光感受器功能的关键是传输 它们对光产生的信号传给视网膜中的其他神经元，用于处理视觉信号和 它们与大脑的通讯。为了实现这一点，光感受器形成复杂的突触 下游神经元，双极细胞(BC)。光感受器和视神经之间的突触通讯缺陷 已知双极细胞导致人类先天性静止性失明，各种形式的视杆/视锥 营养不良，并经常与许多其他眼部疾病并存。我们合作的长期目标是 该计划是获得启用突触的机制的分子组织的原子水平的视图 光感受器的交流，希望能更好地了解致盲条件和设计 他们的治疗策略。 我们实验室和其他实验室最近的研究已经确定了几个对 光感受器的突触通讯。我们进一步发现，这些组件中的许多都是 支架形成跨越突触间隙的大分子组件，并物理上整合突触前 BC区具有突触后受体的光感受器元件。具体来说，我们发现突触后 BC上的受体：mGluR6与光感受器中的两个细胞黏附分子ELFN1和ELFN2相互作用。 此外，驱动BC兴奋以响应突触光感受器输入的机制是 与孤儿受体GPR179相关，而GPR179又与突触前细胞黏附样整合 光感受器中的皮卡丘林分子(Pika)。我们还记录了失去这个组织将废除 突触传递导致夜盲。然而，目前我们对此一无所知 这些跨突触复合体的结构基础。 拟议的研究旨在通过确定关键的跨突触的原子结构来填补这一空白 支架：ELFN1-mGluR6和Pika-GPR179复合体，并探讨其生化机制。这将是 通过高度协同的国际合作，利用生物化学和细胞生物学的专业知识来实现 光感受器突触蛋白及其高分辨低温电子显微镜的最新进展 (CryoEM)获得络合物的高分辨分子结构，探讨其机理。 非常精确的水准仪。这一建议的前提是理解大脑皮质的突触组织 光感受器将为改善失明带来新的治疗策略。

PROJECT SUMMARY Rod and cone photoreceptors are indispensable for our vision. Their death or dysfunction is an underlying cause for a vast majority of blinding retina conditions. Key to photoreceptor function is the ability to transmit the signal that they generate in response to light to other neurons in the retina for processing of visual signals and their communication to the brain. For this to occur, photoreceptors form elaborate synapses with the downstream neurons, the bipolar cells (BC). Deficits in synaptic communication between photoreceptors and bipolar cells are known to cause congenital stationary blindness in humans, various forms of rod/cone dystrophies and frequent co-morbidity with many other ocular conditions. The long term goal of our collaborative program is to obtain atomic level view of molecular organization of machinery that enable synaptic communication of the photoreceptors with the hope to better understand blinding conditions and devising strategies for their treatment. Recent research from our laboratories and others have identified several molecules critical for the synaptic communication of photoreceptors. We have further discovered that many of these components are scaffolded into macromolecular assemblies that span the synaptic cleft and physically integrate pre-synaptic elements of photoreceptors with post-synaptic receptors in BC. Specifically, we found that the postsynaptic receptor on BC: mGluR6 interacts with two cell-adhesion molecules in photoreceptors: ELFN1 and ELFN2. Furthermore, the machinery that drives excitation of BC in response to synaptic photoreceptor inputs is associated with an orphan receptor GPR179 which in turn is integrated with pre-synaptic cell adhesion-like molecule pikachurin (Pika) in photoreceptors. We also documented that loss of this organization abolishes synaptic transmission leading to night blindness. However, at the moment we know absolutely nothing about structural basis of these trans-synaptic complexes. Proposed studies aim to fill this gap by determining the atomic structures of the key trans-synaptic scaffolds: ELFN1-mGluR6 and Pika-GPR179 complexes and probing their biochemical mechanisms. This will be achieved by highly synergistic international collaboration leveraging expertise in biochemistry and cell biology of photoreceptor synaptic proteins and recent advances in high resolution cryogenic electron microscopy (CryoEM) to obtain high resolution molecular structures of the complexes probing their mechanisms at exceedingly precise level. The premise of this proposal is that understanding synaptic organization of photoreceptors would lead to novel therapeutic strategies for ameliorating blindness.