Role of the Arabidopsis TRAPPII tethering complex in division plane establishment

在植物中，间期核的位置决定了有丝分裂进入前的分裂平面。在细胞周期的后期，新生的交叉壁在称为细胞板的短暂膜室中组装。拟南芥转运蛋白颗粒TRAPPII系链复合体是分裂面建立和细胞板形成所必需的。我们使用TRAPPII作为诱饵筛选了条件蛋白相互作用，并验证了有趣的候选物。我们的初步数据导致了TRAPPII是GSK3/shaggy-like激酶（atsk）和PP2A磷酸酶的靶标的工作模型。我们假设TRAPPII磷编码介导植物细胞分裂的时空控制。这笔拨款的重点是分部平面的建立和TRAPPII-PP2A的相互作用；PP2A是TON/TRM/PP2A复合物的一个组分，它是跨壁定向所必需的。我们的具体目的是：(1)阐明TRAPPII在分裂面建立中的作用，(2)阐明PP2A在调节TRAPPII定位和功能中的作用，(3)确定TRAPPII是否是PP2A磷酸酶的底物。我们将结合分子，遗传，细胞生物学，生化和蛋白质组学的方法来解决这些目标。AtSK和PP2A基因家族整合了大量的生物和非生物信号，从而可以通过TRAPPII磷编码指导运输、动员和分类决策。除了对分裂平面建立的新见解外，本研究还将更广泛地阐明在毛茸茸样激酶和PP2A的下游，TRAPPII如何根据环境和发育线索调节贩运。

In plants, the position of the interphase nucleus determines the division plane prior to mitotic entry. Later in the cell cycle, nascent cross walls are assembled in a transient membrane compartment referred to as the cell plate. The Arabidopsis transport protein particle TRAPPII tethering complex is required for both division plane establishment and cell plate formation. We have screened for conditional protein-protein interactions using TRAPPII as bait and have validated interesting candidates. Our preliminary data has led to the working model that TRAPPII is a target of GSK3/shaggy-like kinases (AtSKs) and PP2A phosphatases. We posit that a TRAPPII phosphocode mediates the spatiotemporal control of plant cytokinesis. This grant focuses on division plane establishment and on the TRAPPII-PP2A interaction; PP2A is a component of the TON/TRM/PP2A complex, which is required for cross wall orientation. Our specific aims are to (1) elucidate the role of TRAPPII in division plane establishment, (2) elucidate the role of PP2A in regulating TRAPPII localization and function, (3) establish whether TRAPPII is a PP2A phosphatase substrate. We will combine molecular, genetic, cell biological, biochemical and proteomic approaches to address these goals. The AtSK and PP2A gene families integrate a vast number of biotic and abiotic signals and could thereby instruct trafficking, mobilization and sorting decisions via the TRAPPII phosphocode. In addition to new insights on division plane establishment, this study will more broadly elucidate how, downstream of shaggy-like kinases and PP2A, TRAPPII regulates trafficking in response to environmental and developmental cues.