Interplay between the exocyst complex and Tor signal transduction in the fission yeast Schizosaccharomyces pombe

确保正确生长和发育的调节对于每个生物体的生存至关重要。为了维持细胞内稳态，细胞已经进化出越来越复杂的调节生长和分裂的过程。所有这些过程都涉及到对环境中营养物质或压力源的感知。应激因子影响质膜中的特定蛋白质，这些蛋白质作为分子开关打开应激信号通路以减少生物体的生长。相反，营养丰富的环境通过营养物质本身激活促进细胞生长的信号网络来促进生长。一旦被激活，这些信号网络控制涉及调节细胞生长和大小的细胞过程。其中之一包括细胞内贩运。胞吐作用和胞吞作用都在传递突出细胞外周所需的物质方面发挥关键作用，而且在去除质膜中的营养转运蛋白、受体和脂质结构域方面也发挥关键作用，使得生长发生在正确的细胞位置并以调节的速率进行。一种涉及胞吞和胞吞的运输复合物是外囊复合物，外囊是一种保守的异源八聚体复合物，被认为将货物束缚在质膜上。虽然大多数这些胞吐相关的货物仍在等待鉴定，参与营养摄取的蛋白质已被证明是依赖于胞吐介导的胞吐。外囊成员的突变也导致内吞作用的缺陷，揭示了该复合物在这些组分的逆行运输中的作用。此外，外囊的成员参与了应激信号通路的激活。这使得外囊作为压力和营养感测的潜在主调节器，通过其调节细胞表面的压力和营养感测器的水平，并可能将其桥接到信号网络。他们将结合遗传学、细胞生物学和生物化学技术，并利用裂变酵母S的实验能力来解决这个问题。这位博士生将通过利用裂变酵母S的实验能力来解决这个问题。粟酒酵母与脊椎动物神经元培养物结合。使用一系列遗传，生物化学和荧光成像技术，博士生将使用酵母来识别肌动蛋白组织中胞吐系统的合作伙伴，并将结论应用于脊椎动物神经元。由于其固有的复杂性，神经元形态的变化目前实际上是不可能评估的。将开发一个自动化图像处理框架，从细胞边界的荧光图像中客观地提取形态信息，从中可以得出定量结论。这个工具将有助于探测不同种类生物体的细胞形状特征。总而言之，这些数据将为真菌、植物和动物在整个进化过程中使用的普遍机制提供新的见解。

Regulation to ensure correct growth and development is paramount for the survival of every organism. For cellular homeostasis to be maintained, cells have evolved with ever more complex processes that regulate growth and division. All these processes involve the sensing of the environment for nutrients or stressors. Stressors affect specific proteins in the plasma membrane which act as molecular switches to turn on stress signalling pathways to reduce growth of the organism. Conversely, nutrient rich environments promote growth through the nutrients themselves activating signalling networks that promote cellular growth.Once activated, these signalling networks control cellular processes involved in modulating cell growth and size. One of these includes intracellular trafficking. Both exocytosis and endocytosis play key roles in the delivery of materials needed to protrude the cell periphery, but also the removal nutrient transporters, receptors, and lipid domains in the plasma membrane so that growth occurs in the correct cellular location and at a regulated rate. One trafficking complex that has been implicated in both exo- and endocytosis is the exocyst complex.The exocyst is a conserved hetero-octameric complex that is thought to tether cargoes to the plasma membrane. While most of these exocyst related cargoes are still awaiting identification, proteins involved in nutrient uptake have been shown to be dependent on exocyst mediated exocytosis. Mutation of exocyst members also results in defects in endocytosis, revealing a role for this complex in the retrograde transport of these components too. Furthermore members of the exocyst have been implicated in the activation of stress signalling pathways. This places the exocyst as a potential master regulator of stress and nutrient sensing via its modulation of the level of stress and nutrient sensors at the cell surface and possible bridging of this to signalling networks.A PhD student will test the hypothesis that the exocyst complex is involved in nutrient sensing through regulation of Tor signalling. They will tackle this question using a combination of genetics, cell biology and biochemical techniques, and by exploiting the experimental power of the fission yeast S. pombe.The PhD student will tackle this question by exploiting the experimental power of the fission yeast S. pombe in conjunction with vertebrate neuronal cultures. Using a range of genetic, biochemical and fluorescent imaging techniques the PhD student will use yeast to identify the partners of the exocytic system in actin organisation and apply the conclusions to vertebrate neurons. Due to their inherent complexity, variations in neuron morphology are currently practically impossible to assess. An automated image processing framework will be developed to objectively extract morphological information from fluorescent images of the cells' borders, from which quantitative conclusions may be drawn. This tool will help probe features of cell shape across classes of organism. All in all, these data will provide novel insights into a universal mechanism that is utilised throughout evolution, in fungi, plants and animals.