Understanding Photoreceptor Trafficking Pathways to the Outer Segment

 描述（由申请人提供）：视觉的第一步发生在视网膜中，其中光被感光细胞的外段捕获。这种感光细胞器是独特的，因为它是一种由参与视觉信号转导的一组专门蛋白质组成的修饰的初级纤毛。这些蛋白质在细胞索马中合成，并使用离散的细胞内运输机制递送至外节。这些运输机制对于光感受器的发育和一般维持至关重要，因为外节是必须不断更新的动态结构。在指导阶段，我将完成三个正在进行的，相互关联的项目，解决如何建立细胞内贩运机制，并需要外段稳定。首先，我将解释视紫红质的特征及其运输途径是如何形成外节所必需的。第二，我将确定范围的Arf4参与视紫红质贩运外节通过分析一个杆特异性Arf4基因敲除小鼠。最后，我将确定和完善积极的靶向结构域内编码的蛋白质定位在外部段。这种全面的方法将促进我的过渡到独立的阶段，在此阶段中，我建议阐明信号蛋白是如何分离之间的光盘和外段的质膜子域。我的提议对于理解遗传性视网膜变性的病理生物学过程具有广泛的意义，其中许多是由影响蛋白质运输到感光细胞外段的突变引起的。

 DESCRIPTION (provided by applicant): The first step of vision takes place in the retina where light is captured by the outer segment of photoreceptor cells. This light-sensing organelle is unique in that it is a modified primary cilium that is composed of a specialized group of proteins involved in visual signal transduction. These proteins are synthesized in the cell soma and use discrete intracellular trafficking mechanisms to be delivered to the outer segment. These trafficking mechanisms are critical for development and general maintenance of photoreceptors, as the outer segment is a dynamic structure that must be continuously renewed. During the mentored phase I will complete three ongoing, interconnected projects that address how intracellular trafficking mechanisms are established and required for outer segment stability. First, I will decipher how the features of rhodopsin and its trafficking pathway are necessary for outer segment formation. Second, I will determine the scope of Arf4 involvement in rhodopsin trafficking to outer segments by analyzing a rod-specific Arf4 knockout mouse. Finally, I will identify and refine active targeting domains encoded within proteins localized in the outer segment. This comprehensive approach will facilitate my transition to the independent phase, in which I propose to elucidate how signaling proteins are segregated between the disc and the plasma membrane subdomains of the outer segment. My proposal has broad implications for understanding the pathobiological processes underlying cases of inherited retinal degenerations, many of which are caused by mutations affecting protein trafficking to the photoreceptor outer segment.