Elucidating conserved mechanisms of noncentrosomal microtubule array formation

描述（由申请人提供）：微管形成特化阵列，在细胞分裂、细胞迁移、运输和细胞形态发生中具有重要功能。中心体锚定的微管的放射状阵列对于增殖和迁移的动物细胞是典型的。然而，分化的动物细胞，以及所有的植物细胞，可以组织他们的微管没有中心体。尽管非中心体微管阵列与重要的细胞功能有关，包括细胞内运输和细胞极性，但对中心体缺失时微管的组织机制知之甚少。 在我们的初步研究过程中，我们发现在模式植物拟南芥中的微管阵列是由进化上保守的蛋白磷酸酶PP 2A复合物，包括B”调节亚基TON 2调节。这一建议将阐明PP 2A依赖的非中心体微管阵列形成的分子机制。 第一个目标是建立PP 2A依赖性信号通路和微管相关蛋白TON 1A之间的功能关系，TON 1A在我们的初步研究中被鉴定为推定的TON 2/PP 2A效应子。TON 1A在微管成核和稳定性中的功能将被确定，TON 2/PP 2A信号转导在TON 1A磷酸化调节中的作用将被解决。拟议的实验将提供重要的见解微管阵列形成过程中的微管成核和稳定性的调节机制。 该项目的第二个目的是使用敏化遗传筛选来识别和表征TON 1A/TON 2/PP 2A通路的组分。这将为全面了解PP 2A依赖机制调节非中心体微管阵列的形成奠定基础。

DESCRIPTION (provided by applicant): Microtubules form specialized arrays with important functions in cell division, cell migration, trafficking and cell morphogenesis. Radial arrays of centrosome-anchored microtubules are typical for proliferating and migrating animal cells. However, differentiated animal cells, as well as all plant cells, can organize their microtubules without centrosomes. Although noncentrosomal microtubule arrays have been implicated in vital cellular functions, including intracellular transport and cell polarity, very little is known aboutthe mechanisms organizing microtubules in the absence of centrosomes. In the course of our preliminary studies we found that microtubule arrays in the model plant Arabidopsis thaliana are regulated by the evolutionally conserved protein phosphatase PP2A complex that includes B" regulatory subunit TON2. This proposal will elucidate the PP2A dependent molecular mechanisms of noncentrosomal microtubule array formation. The first aim will establish the functional relationship between the PP2A dependent signaling pathway and the microtubule associate protein TON1A, which was identified in our preliminary studies as a putative TON2/PP2A effector. Functions of TON1A in microtubule nucleation and stability will be determined, and the role of TON2/PP2A signaling in regulation of the TON1A phosphorylation will be addressed. Proposed experiments will provide important insights into mechanisms regulating microtubule nucleation and stability during microtubule array formation. The second aim of the project is to identify and characterize components of the TON1A/TON2/PP2A pathway using a sensitized genetic screen. This will set the stage for a comprehensive understanding of PP2A dependent mechanisms regulating formation of noncentrosomal microtubule arrays.