Self-organization of the radial microtubule array

描述(申请人提供)：细胞质的组织至关重要 对活细胞中发生的所有过程都很重要，包括 细胞划分、细胞代谢和细胞分裂。据信， 微管系统在细胞质的组织中起着关键作用。 通过形成支持膜流量并确定 细胞器的位置。径向阵列的形成通常假设为 是MT在中心体成核的结果，中心体通常位于 细胞的中心。然而，最近的研究表明，细胞有一个 卓越自组织能力和通常使用MTS的MT马达 又可以将MT排列成放射状阵列。它的作用机制 自我组织在很大程度上仍不为人所知。建议的总体目标是 研究是为了阐明定义形成的自组织机制 以及体内放射状MT阵列的居中。我们最近的观察 建立了实验系统，可以解决这些问题。这个 该系统涉及色素细胞、黑素细胞的细胞质碎片。在……里面 黑素载体，数以千计的色素颗粒迅速聚集到中心或 在整个细胞质中重新分散。颗粒通过MT马达运动。 缺乏中心体的黑素细胞胞质碎片迅速形成并 将胞质MT的放射状排列置于中心位置。这种情况的形成 阵列需要存在颜料颗粒、MT动力学和 MT马达的活性，胞浆动力蛋白。一种实验性的组合 包括数字荧光显微镜、光漂白、 光激活、激光显微外科手术和显微注射运动特异性探针 将被用来阐明自组织和自中心的机制 黑素载体碎片。具体地说，我们将揭开MT的机制 控制MTS空间组织的色素聚集体上的成核作用。 我们将定位定心力的产生地点并确定 MT电机在径向MT阵列定位中的作用。最后，我们会 确定分子组分的最小补充量 自组织和自中心，通过重建这些现象在 体外培养。这些研究对于了解心力衰竭的一般机制具有重要意义。 细胞组织，也用于设计新的治疗策略 旨在预防和治疗疾病。

DESCRIPTION (provided by applicant): Organization of cytoplasm is crucially important to all the processes that occur in living cells, including compartmentalization, cell metabolism, and cell division. It is believed that the system of microtubules (MTs) plays a key role in organizing the cytoplasm by forming a radial array that supports membrane traffic and determines positions of organelles. Formation of the radial array is generally assumed to be a result of MT nucleation at the centrosome, which often locates in the center of a cell. Recent studies indicate, however, that cells have a remarkable self-organizing capacity and that MT motors, which normally use MTs as 'rails', may in turn arrange MTs into a radial array. The mechanisms of self-organization remain largely unknown. The overall goal of the proposed research is to elucidate the self-organization mechanisms that define formation and centering of the radial MT array in vivo. Our recent observations established experimental system, which allows addressing these questions. The system involves cytoplasmic fragments of pigment cells, melanophores. In melanophores, thousands of pigment granules rapidly aggregate to the center or redisperse throughout the cytoplasm. The granules move by means of MT motors. Cytoplasmic fragments of melanophores lacking the centrosome rapidly form and position to the center the radial array of cytoplasmic MTs. Formation of such an array requires the presence of pigment granules, MT dynamics and the activity of a MT motor, cytoplasmic dynein. A combination of experimental techniques that include digital fluorescence microscopy, photobleaching, photoactivation, laser microsurgery and microinjection of motor-specific probes will be used to elucidate mechanisms of self-organization and self-centering in melanophore fragments. Specifically, we will unravel the mechanism of MT nucleation on the pigment aggregates that controls spatial organization of MTs. We will locate the sites of production of the centering force and determine the role for MT motors in positioning of the radial MT array. Finally, we will determine the minimal complement of molecular components essential for the self-organization and self-centering by reconstituting these phenomena in vitro. These studies are important for understanding the general mechanisms of cellular organization but also for the design of new therapeutic strategies aimed at prevention and treatment of disease.