The Role of the Actin Cytoskeleton in Regulation of Auxin Transport

9318250本实验室的最新证据表明，西葫芦生长素外流载体的调节性或抑制物结合亚基与肌动蛋白细胞骨架有关。近年来，肌动蛋白细胞骨架的作用已被证明不仅仅是结构性的。这种丝状网络在多种生物体中的细胞内运动、极性发展和细胞信号的整合中发挥作用。尽管到目前为止，肌动蛋白细胞骨架在高等植物生长发育中的作用研究有限，但肌动蛋白微丝在褐藻(Fucus)环境控制的极性发育中的作用已经得到了很好的描述。很可能，肌动蛋白细胞骨架的变化在开花植物的发育和环境反应中起着同样重要的作用。植物细胞骨架非常适合作为信号传导器，从膜和细胞外基质感知外部事件，到生长素运输流，从而对这些信号做出反应。这一方案中的实验旨在验证生长素极性运输受生长素外流载体的调节蛋白与细胞骨架相互作用调节的新假说。为了了解生长素转运调控的本质，必须进一步阐明生长素外排载体的抑制物或NPA结合蛋白与肌动蛋白之间的相互作用。使用分子探针和基本的生化方法，将研究极地发育过程中NPA结合蛋白和肌动蛋白细胞骨架之间的相互作用。这些实验将使用Fucus作为简化的模型系统来执行。尽管自达尔文提出植物中极性激素运输的重要性以来，已经有一百多年了，但生长素运输的调节机制仍然不清楚。生长素转运的极性和数量是在生长素从细胞外流的部位控制的。已经确定了一种调节蛋白，它与生长素转运的特定抑制物结合，作用于生长素外流部位。这种抑制物结合蛋白的特性及其控制生长素运输的机制，是剖析生长素运输调控途径的关键第一步。***

9318250 Muday Recent evidence from this laboratory indicates that the regulatory or inhibitor binding subunit of the auxin efflux carrier from zucchini is associated with the actin cytoskeleton. In recent years, the role of the actin cytoskeleton has been shown to be more than structural. This filamentous network functions in intracellular movement, polarity development, and integration of cellular signals in a variety of organisms. Although the role of the actin cytoskeleton in the growth and development of higher plants has so far received limited study, the role of actin microfilaments in the environmentally controlled development of polarity of the brown alga, Fucus, has been elegantly described. It is likely that changes in the actin cytoskeleton play equally important roles in the development and environmental responses of flowering plants. The plant cytoskeleton is uniquely suited to act as the signal transducer from the membrane and extracellular matrix, which sense external events, to the auxin transport stream which allows response to these signals. The experiments in this proposal are designed to test the new hypothesis that polar auxin transport is regulated by interactions of the regulatory protein of the auxin efflux carrier with the cytoskeleton. In order to understand the nature of the regulation of auxin transport, the interaction between the inhibitor or napthylphthalamic acid (NPA) binding protein of the auxin efflux carrier and actin must be further delineated. Using molecular probes and basic biochemical approaches, the interactions between the NPA binding protein and the actin cytoskeleton during polar development will be examined. These experiments will be performed using Fucus as a simplified model system. Although it has been more than one hundred years since Darwin suggested the importance of polar hormone transport in plants, the mechanisms by which auxin transport is regulated still remain unclear. The polarity a nd quantity of auxin transported are controlled at the site of auxin efflux from cells. A regulatory protein has been identified which binds specific inhibitors of auxin transport that act at the site of auxin efflux. Characterization of this inhibitor binding protein, and the mechanisms by which it controls auxin transport, is the critical first step in the dissection of the regulatory pathway of auxin transport. ***