MODELING ORGANELLE TRAFFICKING

这个子项目是利用由NIH/NCRR资助的中心拨款提供的资源的许多研究子项目之一。子项目和调查员(PI)可能从另一个NIH来源获得了主要资金，因此可能会出现在其他CRISE条目中。列出的机构是针对中心的，而不一定是针对调查员的机构。该项目的目的是了解微管(MT)依赖和肌动蛋白细丝(AF)转运之间的协调机制，使用鱼类黑素载体作为实验系统。这些大细胞的唯一功能是快速和同步地重新分布数以千计的膜结合的细胞器，即色素颗粒，它们聚集在细胞中心或均匀地重新分散在细胞质中。聚集过程中的色素重新分配涉及到MTS的负端的运输。色素弥散结合了最初向MT+末端的快速移动和沿AFS的缓慢扩散样移动，导致色素在细胞质中均匀分布。因此，色素的运输需要不同细胞骨架特异性和极性的多个马达活动的协调。我们最近的工作使用了对颜料颗粒的高分辨率跟踪来确定颜料颗粒在聚集和分散过程中沿MTS和AFS的运动参数的变化。这些运动参数反映了颗粒结合分子马达的活性。这一分析结果表明，两个转运系统之间的转换是由第二信使cAMP的细胞质水平控制的，第二信使cAMP通过选择性地调节依赖于MT和AF的单个运动的活动来决定每个转运系统的贡献。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The goal of this project is to understand the mechanisms for the coordination between microtubule (MT)-dependent and actin filament (AF) transport using fish melanophores as an experimental system. The only function of these large cells is fast and synchronous redistribution of thousands of membrane-bounded organelles, pigment granules, which aggregate at the cell center or redisperse uniformly throughout the cytoplasm. Pigment redistribution during aggregation involves transport to the minus ends of MTs. Pigment dispersion combines initial rapid movement to the MT plus ends and slow diffision-like movement along the AFs, which results in the homogeneous distribution of pigment in the cytoplasm. Therefore pigment transport requires coordination of the activities of multiple motors of different cytoskeletal specificity and polarity. Our recent work employed high resolution tracking of pigment granules to determine changes in the movement parameters of pigment granules along MTs and AFs during aggregation and dispersion. These movement parameters reflect the activities of the granule-bound molecular motors. The results of this analysis demonstrated that the switching between the two transport systems is controlled by the cytoplasmic levels of the second messenger cAMP, which determines the contribution of each transport system by selectively regulating the activities of individual MT- and AF-dependent motors.