Elucidating conserved mechanisms of noncentrosomal microtubule array formation

描述(申请人提供)：微管形成专门的阵列，在细胞分裂、细胞迁移、运输和细胞形态形成中具有重要功能。放射状中心体锚定的微管阵列对于动物细胞的增殖和迁移是典型的。然而，分化的动物细胞和所有植物细胞都可以在没有中心体的情况下组织它们的微管。虽然非中心体微管阵列与重要的细胞功能有关，包括细胞内转运和细胞极性，但在没有中心体的情况下，微管的组织机制知之甚少。在我们的初步研究过程中，我们发现模式植物拟南芥中的微管阵列受进化保守的蛋白磷酸酶PP2A复合体的调控，该复合体包括B“调节亚单位ton2。这一建议将阐明PP2A依赖的非中心体微管阵列形成的分子机制。第一个目的是建立PP2A依赖的信号通路和微管相关蛋白TON1A之间的功能关系，该蛋白在我们的初步研究中被确定为可能的ton2/PP2A效应因子。将确定TON1a在微管成核和稳定性中的功能，并讨论ton2/PP2A信号在调节TON1a磷酸化中的作用。所提出的实验将为微管阵列形成过程中调节微管成核和稳定性的机制提供重要的见解。该项目的第二个目标是使用敏化遗传筛选来确定和表征TON1A/TON2/PP2A途径的组成部分。这将为全面理解PP2A依赖的调控非中心体微管阵列形成的机制奠定基础。

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.