Spatial Regulation of Cytoskeletal Asymmetry

描述（由申请人提供）：高等生物中的细胞迁移对于多种生理和病理生理过程至关重要，包括胚胎发育和免疫反应。癌细胞中细胞运动的改变是恶性肿瘤最危险的特征之一，因为它建立了它们的侵袭和转移潜力。微管阵列的极化组织是极化细胞运动的必要条件。然而，这一规定的原则尚不清楚。一般认为脊椎动物细胞中的微管是由中心体形成的。我们最近证明了大量的微管起源于高尔基体（Efimov et al, 2007）。我们已经确定了两个对这种新现象至关重要的分子：微管调节蛋白CLASPs是形成高尔基衍生微管所必需的，而golgin GCC185在高尔基外围的反式高尔基网络（TGN）中作为CLASPs的锚点。与中心体组织的对称微管阵列形成鲜明对比的是，在运动细胞中，外围高尔基室有核的微管优先朝向前沿。初步数据表明，缺乏高尔基起源微管的细胞的迁移潜力受到损害。在这个提议中，我们将测试假设不对称微管成核在高尔基体是运动细胞极化的关键。我们将测试源于高尔基的微管是否通过调节肌动蛋白细胞骨架或定向后高尔基转运到细胞前部来发挥其对细胞极性的影响，或两者兼有。我们还将讨论调节TGN微管形成的分子机制。我们的具体目标是：1。确定高尔基衍生微管在运动细胞的细胞骨架极性中的作用。2. 确定高尔基衍生微管在运动细胞极化高尔基转运中的作用。3. 确定动态CLASP锚定是否会影响高尔基体的微管组织潜能。

DESCRIPTION (provided by applicant): Cell migration in higher organisms is essential for multiple physiological and pathophysiological processes, including embryonic development and immune responses. Alteration of cell motility in cancer cells is one of the most dangerous features of malignant tumors, as it builds up their invasive and metastatic potential. Polarized organization of microtubule arrays is essential for polarized cell motility. However, the principles of this regulation are not yet understood. It is generally assumed that microtubules in vertebrate cells are formed by the centrosome. We have recently demonstrated that a large number of microtubules originate from the Golgi apparatus (Efimov et al, 2007). We have identified two molecular players critical for this novel phenomenon: microtubule regulatory proteins CLASPs are required for the formation of Golgi-derived microtubules, and golgin GCC185 serves as an anchor for CLASPs at the trans-Golgi network (TGN) at the Golgi periphery. In sharp contrast to symmetric microtubule arrays organized by the centrosome, microtubules nucleated at the peripheral Golgi compartment are preferentially oriented toward the leading edge in motile cells. Preliminary data suggest that the migratory potential of cells lacking Golgi-originated microtubules is compromised. Within this proposal, we will test the hypothesis that asymmetric microtubule nucleation at the Golgi is critical for motile cell polarization. We will test whether Golgi-originated microtubules exert their effect on cell polarity via regulation of the actin cytoskeleton or directional post-Golgi transport to the cell front, or both. We will also address molecular mechanisms that regulate microtubule formation at the TGN. Our specific aims are: 1. Determine the role of Golgi-derived microtubules in the cytoskeletal polarity of motile cells. 2. Determine the role of Golgi-derived microtubules in polarized Golgi trafficking in motile cells. 3. Determine if dynamic CLASP anchoring underlies the microtubule-organizing potential of the Golgi. PUBLIC HEALTH REVELANCE: Knowledge of the molecular events that underlie cell motility is critical for understanding major health-related processes, including embryonic morphogenesis, wound healing, the immune response and cancer invasiveness. As major anticancer therapies include microtubule-specific drugs, knowledge their potential targets is especially valuable. In this proposal, we will carry out research that will determine the role of a novel Golgi-derived asymmetric microtubule array in cell motility.