Mechanisms that maintain and remodel the sensory cilium

项目摘要 感觉神经元将用于检测环境刺激的分子集中并组织到纤毛中， 细胞表面上的专门的基于微管的结构，其用作细胞天线。的蛋白质 构成感觉传导机制的神经元在别处合成，必须与 其他细胞蛋白质和运输到纤毛。调解贩运人口的机制的重要性 引起疾病的突变破坏了这一过程。突变 损害了色素视紫红质或鸟苷酸环化酶的纤毛运输， 以光感受器退化为标志的营养不良，最终导致失明。尽管重要的是 蛋白质运输到纤毛，其潜在的分子机制仍然知之甚少。我们建议 利用线虫C.作为发现机制的模型， 选择和运输预定用于感觉纤毛的货物。与脊椎动物感光神经元一样，BAG 神经元使用环GMP作为感觉传导的第二信使， 控制环GMP信号并将其转化为电信号的方法与 感光神经元蛋白质向BAG纤毛的运输可以使用高分辨率的 荧光显微镜分析和强大的遗传工具可用于急性或慢性操纵 BAG神经元中的特异性分子通路，并决定其在运输到纤毛中的功能。 重要的是，C。elegans允许发现新的因子，其通过遗传途径介导纤毛运输， 屏幕和生化方法。我们建议使用这个强大的实验系统来（1）描绘一个 一种分子途径，它将运往感觉纤毛的货物与携带它的特定马达相匹配 通过树突到达其目的地，以及（2）确定贩运机制如何通过 触发BAG纤毛重塑的生理或发育线索。这些研究将进一步 理解对感觉神经元功能和活力至关重要的细胞过程，并将整合 细胞运输机制与影响感觉纤毛的生理和发育程序， vivo.

PROJECT SUMMARY Sensory neurons concentrate and organize molecules used to detect environmental stimuli into cilia, which are specialized microtubule-based structures on the cell surface that function as cellular antennas. The proteins that constitute the machinery of sensory transduction are synthesized elsewhere and must be separated from other cellular proteins and transported to the cilium. The importance of mechanisms that mediate trafficking of proteins to the sensory cilium is illustrated by disease-causing mutations that disrupt this process. Mutations that compromise ciliary trafficking of the photopigment rhodopsin or the enzyme guanylyl cyclase cause retinal dystrophies marked by photoreceptor degeneration and, ultimately, blindness. Despite the importance of protein trafficking to the cilium, its underlying molecular mechanisms remain poorly understood. We propose to use chemosensory BAG neurons of the nematode C. elegans as a model for discovery of mechanisms that select and transport cargo destined for the sensory cilium. Like vertebrate photoreceptor neurons, BAG neurons use cyclic GMP as a second messenger for sensory transduction, and the enzymes and effectors that control cyclic GMP signals and turn them into electrical signals are highly similar to those found in photoreceptor neurons. Trafficking of proteins to BAG cilia can be measured in situ using high-resolution fluorescence microscopy assays, and powerful genetic tools are available to acutely or chronically manipulate specific molecular pathways in BAG neurons and determine their function in trafficking to the cilium. Importantly, C. elegans permits discovery of novel factors that mediate ciliary trafficking through genetic screens and biochemical approaches. We propose to use this powerful experimental system to (1) delineate a molecular pathway that matches cargo destined for the sensory cilium with specific motors that will carry it through the dendrite to its destination, and (2) determine how trafficking mechanisms are regulated by physiological or developmental cues that trigger remodeling of the BAG cilium. These studies will advance understanding of a cellular process that is essential for sensory neuron function and viability and will integrate cellular trafficking mechanisms with physiological and developmental programs that impact sensory cilia in vivo.