Mechanisms of photoreceptor disc maturation

这个提议中描述的实验解决了视觉中最迷人的未解之谜 研究感光细胞外节形态发生的分子机制。的 外节是响应于捕获光而产生电信号的纤毛细胞器。一个独特 外段的形态特征是它填充有一堆扁平的膜盘， 用于光子捕获和信号放大的表面。这种解剖结构的功能意义 已经认识了很长一段时间，但我们的理解光盘是如何建立在分子水平仍然存在 令人沮丧的原始本申请解决了感光盘的几个知之甚少的方面 形态发生，与椎间盘扩张、排列和封闭过程有关。我们的初步数据显示 新形成的椎间盘的边缘包含两种不同类型的细胞外连接：一种连接椎间盘与 内节质膜和另一个连接盘边缘之间。述实验 在目的1和2中，将致力于确定每种连接类型的蛋白质组成，并阐明其 在支持磁盘拉伸和堆叠的高保真度方面发挥特定作用。目标3将集中在光盘的最后一步 由其从外节质膜上断裂而成的成熟过程。我们将讨论是否光盘 断裂只发生在杆和探索分子球员参与这一过程。实验 本申请中描述的方法将采用与现有技术的三种分子工具相结合的通用分子工具 外部节结构的三维电子显微镜断层扫描分析。解决这些 机械问题对于推进我们对感光细胞生物学的基本理解至关重要， 阐明了遗传性失明的病理生理机制， 外节形态发生

The experiments described in this proposal address one of the most fascinating unanswered questions in vision research regarding the molecular mechanisms responsible for photoreceptor outer segment morphogenesis. The outer segment is a ciliary organelle that produces electrical signals in response to capturing light. A unique morphological feature of the outer segment is that it is filled with a stack of flattened membrane discs providing vast surfaces for photon capture and signal amplification. The functional significance of this anatomical arrangement has been recognized for a very long time, yet our understanding of how discs are built at the molecular level remains frustratingly rudimentary. This application addresses several poorly understood aspects of photoreceptor disc morphogenesis, related to the processes of disc expansion, alignment and enclosure. Our preliminary data show that the edges of newly formed discs contain two distinct types of extracellular links: one connecting discs with the inner segment plasma membrane and another connecting disc edges between themselves. Experiments described in Aims 1 and 2 will be devoted to determining the protein composition of each link type and elucidating their specific roles in supporting the high fidelity of disc elongation and stacking. Aim 3 will focus on the final step in disc maturation consisting of its scission from the outer segment plasma membrane. We will address whether disc scission takes place exclusively in rods and explore molecular players involved in this process. Experiments described in this application will employ versatile molecular tools combined with the state-of-the-art three dimensional electron microscopy tomographic analysis of the outer segment structure. Addressing these mechanistic questions is essential for advancing our basic understanding of photoreceptor cell biology, as well as elucidating the pathophysiological mechanisms underlying inherited blindness frequently associated with defects in outer segment morphogenesis.