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很感兴趣。被吸收的物质被包装成小的球形囊泡，这些囊泡从细胞表面进入细胞。细胞内部的一层蛋白质外壳包围着进入的囊泡，帮助它发芽。网格蛋白是一种主要的包被蛋白，因此这些囊泡被称为网格蛋白包被囊泡。这些囊泡充当运输载体，将物质运送到细胞内另一个称为内核体的隔间，内核体作为主要的细胞分选站，将物质送到另一个细胞内隔间，即溶酶体中分解，或将其回收到细胞表面。网格蛋白帮助囊泡在细胞的许多位置发芽。蒙代尔和凯利实验室研究的是G蛋白偶联受体（gpcr），这是一种在质膜上发现的蛋白质，它对从环境中接收的各种信息做出反应。这些包括激素、感觉刺激（如气味剂）、神经递质和药物（如吗啡）。由于其生物学作用的范围，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。作为这个过程的一部分，它们也被网格蛋白包裹的囊泡吸收或内化到细胞中，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（再敏化）。如果在磷酸化过程中加入磷酸盐，许多蛋白质的活性就会发生变化。磷酸化是由一组称为激酶的细胞酶完成的。本提案的目的是了解网格蛋白的作用是如何通过磷酸化调节的。我们最近的研究已经证明了一个新的发现，即一种向一些gpcr添加磷酸盐的激酶似乎也会使网格蛋白磷酸化。这可以作为这些特定gpcr的地址标签，将它们发送到细胞内的特定路径上。越来越清楚的是，GPCRs遵循的细胞内路线以及它们沿着这条路线移动的速度会影响它们发出信号的方式，因为信号通常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，可能导致细胞分裂。我们感兴趣的是探索通过磷酸化修饰网格蛋白如何影响信号的传输速率。我们希望这项工作能给我们提供关于细胞如何对信号作出反应的重要信息，从长远来看，我们有可能找到新的治疗靶点。

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.