Regulation of membrane trafficking and signalling by clathrin light chain phosphorylation

Smythe实验室对细胞在内吞过程中从外部环境中吸收物质的方式感兴趣。被吸收的物质被包装成小的球形小泡，这些小泡从细胞表面发芽进入细胞。细胞内层的一层蛋白质包裹着进入细胞的小泡，帮助它发芽。笼状蛋白是一种主要的外壳蛋白，因此这种囊泡被称为笼状蛋白包衣的囊泡。这些小泡充当运输载体，将物质输送到细胞内另一个称为内小体的隔室，内小体充当主要的细胞分选站，要么将材料送到另一个细胞内隔室--溶酶体中分解，要么将其回收到细胞表面。笼蛋白帮助囊泡在细胞的许多位置萌发。蒙代尔和凯利实验室研究G蛋白偶联受体(GPCRs)，这是在质膜上发现的蛋白质，对从环境接收的一系列信息做出反应。这些物质包括荷尔蒙、气味等感官刺激、神经递质和吗啡等药物。由于它们的生物学作用范围广泛，这些受体是主要的药物靶点。当这些受体遇到信号时，它们会通过激活细胞内的各种事件来做出反应。作为这一过程的一部分，它们也被笼罩在细胞内的网状蛋白囊泡吸收或内化，在那里它们可能成为溶酶体破坏的目标(脱敏)，或者被送回细胞表面，在那里它们可以对进一步的刺激做出反应(重新增敏)。如果在磷酸化过程中加入磷酸盐，许多蛋白质的活性可能会改变，这是由一组称为激酶的细胞酶来实现的。这项建议的目的是了解如何通过磷酸化来调节网状蛋白的作用。我们最近的研究证明了这一新的发现，即将磷酸添加到某些GPCRs的一种激酶似乎也可以磷酸化网状蛋白。这可以充当这些特定GPCR的地址标签，在小区内的特定路由上发送它们。越来越清楚的是，GPCR遵循的细胞内路线及其沿这条路线移动的速率影响它们发出信号的方式，因为信号往往会产生不止一种输出。例如，在一种情况下，信号可能导致细胞移动，而在另一种情况下，信号可能导致细胞分裂。我们感兴趣的是探索通过磷酸化修饰的笼蛋白如何影响信号的传输速度。我们希望这项工作将为我们提供细胞如何对信号做出反应的重要信息，从长远来看，我们有可能确定新的治疗靶点。

The Smythe lab is interested in the way in the way in which cells take up material from the external environment in the process of endocytosis. Material to be taken up is packaged into small spherical vesicles that bud into the cell from the cell surface. A protein coat on the inside of the cell surrounds the incoming vesicle and helps it to bud off. Clathrin is one of the major coat proteins and so the vesicles are named clathrin coated vesicles. These vesicles act as transport carriers and deliver material to another compartment within the cell called an endosome, which acts as a major cellular sorting station and either sends the material to be broken down in yet another intracellular compartment, the lysosome, or recycles it back to the cell surface. Clathrin helps vesicles to bud at a number of locations in the cell.The Mundell and Kelly labs study G protein-coupled receptors (GPCRs), which are proteins found on the plasma membrane that respond to a whole range of messages received from the environment. These include hormones, sensory stimuli such as odorants, neurotransmitters and drugs such as morphine. Because of the range of their biological roles, these receptors are major drug targets. When these receptors encounter a signal they respond to it by activating a variety of events within the cell. As part of this process they are also taken up or internalised into the cell by clathrin coated vesicles and there they may either be targeted for destruction in the lysosome (desensitization) or sent back to the cell surface where they can respond to further stimuli (resensitization). The activity of many proteins may be changed if phosphate is added to them in the process of phosphorylation and this is carried out by a group of cellular enzymes called kinases. The aim of this proposal is to understand how the role of clathrin is regulated by phosphorylation. Our recent studies have demonstrated the novel finding that a kinase that adds phosphate to some GPCRs also appears to phosphorylate clathrin. This may act as an address label for these particular GPCRs, sending them on a specific route within the cell. It is becoming increasingly clear that the intracellular routes followed by GPCRs and the rate at which they move along this route affects how they signal because often signals give rise to more than one output. For example in one situation a signal may cause a cell to move and, in another, to divide. We are interested in exploring how modifications of clathrin by phosphorylation may affect the rate of transport of signals. We expect this work to give us important information into how cells respond to signals and in the longer term it is possible that we will identify novel therapeutic targets.