Calcium channels in retinal photoreceptors

我们研究的长期目标是了解CAV通道的特性如何形成它们的 神经功能。此竞争续订申请的目标是定义依赖于CAV1的 影响光感受器突触发育和可塑性的信号通路。其中 Cav1是视网膜表达的主要亚型，Cav1.4对PR突触发生具有独特的关键作用。多么 Cav1.4对这一过程的贡献仍然是一个谜--一个主要的挑战是可用的动物 模型没有区分Cav1.4作为钙离子来源和作为 突触生成蛋白。为了克服这一障碍，我们产生了一个表达Cav1.4的非传导突变形式的敲入小鼠品系。虽然PR突触的分子组织在很大程度上幸免于难 这些小鼠的突触带的成熟和突触后突触向PR终末的内陷 被打乱了。我们的发现提出了一种有趣的可能性，即与CSNB2相关的临床变异性 可能源于突变对组织、开发和成熟的不同影响 PR突触的功能。我们的中心假设是Cav1.4介导的钙信号通路 通过促进突触带的成熟和PR突触后的构筑 CSNB2中中断的机制。我们将以以下目的检验这一假说：(1)阐明 Cav1.4钙信号调节突触带成熟和可塑性的机制(2)定义 Cav1钙信号在PR突触突触后连接中的作用(3)决定 人类Cav1.4通道对PR突触结构和功能的病理变异。我们的整体影响 研究将了解：(A)CAV通道在突触中的多方面作用，这对视力至关重要， 以及(B)Cav1.4的调节失调如何导致不同形式的视力损害。更多 总的来说，我们的研究有望为正确的突触机制提供洞察力 视网膜的连通性--通过细胞移植成功恢复视力的必要条件 治疗。

The long-term goal of our research is to understand how the properties of Cav channels shape their neural functions. The objective of this competing renewal application is to define the Cav1-dependent signaling pathways that shape the development and plasticity of the photoreceptor (PR) synapse. Among the major Cav1 subtypes expressed in the retina, Cav1.4 is uniquely critical for PR synaptogenesis. How Cav1.4 contributes to this process remains a mystery—a major challenge being that available animal models do not distinguish between the roles of Cav1.4 as a source of Ca2+ ions and as a scaffold for synaptogenic proteins. To overcome this hurdle, we generated a knock-in mouse strain expressing a non-conducting mutant form of Cav1.4. While the molecular organization of PR synapses is largely spared in these mice, the maturation of synaptic ribbons and invagination of postsynaptic neurites into PR terminals is disrupted. Our findings raise the intriguing possibility that the clinical variability associated with CSNB2 could arise from heterogeneous impacts of the mutations on the organization, development, and mature function of the PR synapse. Our central hypothesis is that Cav1.4 mediates Ca2+ signaling pathways that promote the maturation of synaptic ribbons and the postsynaptic architecture of PR synapses via mechanisms that are disrupted in CSNB2. We will test this hypothesis with the following Aims: (1) Elucidate the mechanism whereby Cav1.4 Ca2+ signals regulate the maturation and plasticity of synaptic ribbons (2) Define the role of Cav1 Ca2+ signals in enabling the postsynaptic wiring of PR synapses (3) Determine the impact of pathological variants of human Cav1.4 channels on PR synapse structure and function. The overall impact of our research will be knowledge of: (a) the multi-faceted roles of Cav channels at a synapse that is crucial for vision, and (b) how dysregulation specifically of Cav1.4 could lead to heterogeneous forms of vision impairment. More broadly, our research is expected to provide insights into mechanisms that enable the proper synaptic connectivity in the retina—a requirement for the successful restoration of vision through cell transplantation therapies.