Recruitment and phospho-regulation of key division site proteins in plants

植物细胞在有丝分裂前选择其分裂平面，通过细胞骨架前前期带和称为分裂位点驻留蛋白的蛋白质组装来标记圆周。位于细胞皮层的这种蛋白质复合物的核心组分是驱动蛋白-12蛋白质质体定向驱动蛋白（POK），其连续占据分裂位点。POK对于部门站点的维护至关重要，但我们对他们在预定站点的招募知之甚少。植物细胞分裂平面的选择是植物细胞生物学尚未解决的问题之一。建议的研究旨在提高我们的理解，使用POK作为代理划分平面确定。我们将研究POKs是否在整个细胞分裂过程中受到磷酸化调节，以及这种调节如何影响它们的定位和动态。此外，我们将研究这种调节是否涉及蛋白磷酸酶2A复合物的活性，这是必不可少的preprophase带的形成。它的几种组分是POK的直接结合伴侣。此外，我们将描述新的，意想不到的POKs和成员的贝尔样转录因子家族，可能有助于分裂平面的确定之间的相互作用。为了实现这些目标，我们将采用生命细胞显微镜，并结合遗传和生物化学方法使用先进的成像技术。我们希望阐明相关的磷酸调节的分裂网站的建立，并确定一种新的机制，可能包括一个途径的分裂平面的决定，并可能独立于preprophase带。

Plant cells select their division planes before mitosis, marking the circumferences by the cytoskeletal preprophase band and by an assembly of proteins termed division site resident proteins. Core components of this protein complex located at the cell cortex are the kinesin-12 proteins PHRAGMOPLAST ORIENTING KINESINs (POKs), which continuously occupy the division site. POKs are essential for the maintenance of the division site, but we know little about their recruitment to the predetermined site. How the division plane is selected in plants is still one of the unsolved questions in plant cell biology. The proposed research aims to improve our understanding of division plane determination using POKs as a proxy. We will investigate whether POKs are phospho-regulated throughout the course of cell division and how this regulation affects their localization and dynamicity. Moreover, we will examine whether this regulation involves the activity of protein phosphatase 2A complex, that is essential for preprophase band formation. Several of its components are direct binding partners of POKs. Furthermore, we will characterize novel, unexpected interactions between POKs and members of the BELL-like transcription factor family that might contribute to division plane determination. To accomplish these goals, we will employ life-cell microscopy and use advanced imaging techniques in combination with genetic and biochemical approaches. We expect to elucidate the relevance phospho-regulation for the establishment of the division site and to identify a novel mechanism that might encompass a pathway of division plane determination, and that might act independent of the preprophase band.