Mechanisms that maintain and remodel the sensory cilium

项目总结 感觉神经元集中并组织用于检测环境刺激的分子进入纤毛，纤毛是 细胞表面的特殊微管结构，起到细胞天线的作用。这些蛋白质 构成感觉转导机制的物质是在其他地方合成的，必须从 其他细胞蛋白并运输到纤毛。调解贩运人口的机制的重要性 破坏这一过程的致病突变说明了感觉纤毛的蛋白质。突变 损害了感光色素视紫红质或鸟苷酸环化酶导致视网膜的纤毛运输 以光感受器退化为特征的营养不良，最终导致失明。尽管重要的是 蛋白质转运到纤毛，其潜在的分子机制仍然知之甚少。我们建议 利用线虫的化学感觉袋神经元作为发现机制的模型 挑选和运输运往感觉器官纤毛的货物。像脊椎动物的光感受器神经元一样 神经元使用环状GMP作为感觉转导的第二信使，而酶和效应器 控制循环GMP信号并将其转换为电信号与 光感受器神经元。可以使用高分辨率原位测量蛋白质向袋状纤毛的运输 荧光显微镜分析和强大的遗传工具可用于急性或慢性操作 BAG神经元中的特定分子通路，并确定它们在纤毛运输中的功能。 重要的是，线虫允许发现通过基因调节纤毛运输的新因素 筛查和生化方法。我们建议使用这个强大的实验系统来(1)描绘一个 将运往感觉纤毛的货物与携带它的特定马达相匹配的分子途径 通过树枝晶到达其目的地，以及(2)确定贩运机制如何由 触发袋纤毛重塑的生理或发育线索。这些研究将取得进展 对感觉神经元功能和活性至关重要的细胞过程的理解，并将整合 影响感觉纤毛的生理和发育程序的细胞运输机制 活着。

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.