Role of Lamellipodin in fast, clathrin-independent endocytosis.

人体由数十亿个细胞组成。为了让身体正常运作，这些细胞必须相互交流。它们通过发出信号进行交流，这些信号可以被其他细胞表面的“天线”--称为“受体”--识别。当信号到达受体时，受体被激活，从而刺激细胞做出反应并改变它们的行为。信号是通过摄取囊泡从细胞表面移除激活的受体而停止的，囊泡是被膜包围的小隔室。这个过程被称为“内吞作用”。内吞作用对我们身体的正常运作很重要，但如果它“出了问题”，它可能会导致疾病。例如，在伤口愈合的情况下，一旦受伤，伤口中的细胞就会发出信号，吸引其他细胞修复伤口。当这些“修复”细胞接收到信号时，它们会主动迁移到伤口处以关闭伤口。当修复细胞中的内吞过程不能正常工作时，伤口愈合可能会延迟，这可能会导致许多疾病，如糖尿病足溃疡、静脉性腿部溃疡和无法动弹的患者的压疮(压疮)。特别是，在老龄化的人口中，病理性伤口愈合成为一项重大挑战。细胞通过将充当信号的化合物填满细胞“X”内的小泡来发出信号。然后，囊泡被输送到细胞与外界的边界--细胞X的细胞膜，当囊泡的膜与细胞X的膜融合时，内容物被释放到外部。神经细胞之间有许多接触，称为突触，相互传递信号。这是大脑工作的基本基础。在这些突触处，带有存储信号的囊泡被释放，通过囊泡与神经细胞X的膜融合来激活邻近的神经细胞Y。然后信号扩散到神经细胞“Y”，在那里激活感受器。在信号释放时，必须回收囊泡膜以便再次制造囊泡。膜的回收再次由内吞作用调节，称为突触小泡再循环。突触小泡的异常循环损害了神经细胞的交流，这被认为是许多神经精神疾病的原因，这些疾病是对终身健康和福祉的重大挑战，如癫痫、抑郁症和精神分裂症。我们建议利用实验室培养的单个细胞来研究受体内吞作用和突触小泡循环的基本机制。我们将使用生化方法分析细胞如何正常控制受体的摄取。我们还将通过用荧光染料标记囊泡来可视化招募到囊泡中的单个蛋白质。这将使我们能够使用显微镜实时分析活细胞的招募情况。我们的研究可能会让我们揭示不同蛋白质对受体摄取的作用，从而解释这一基本生物过程的机制。我们还将使用显微镜拍摄细胞在培养皿中迁移的电影，同时暴露在来自其他细胞的信号中。我们将使用这项测试来揭示内吞作用如何有助于细胞对信号的定向移动，这在伤口愈合过程中通常会发生。该项目的成果将为我们体内单个细胞的正常功能提供新的见解，并从长远来看，可能为开发针对内吞改变的疾病的靶向治疗提供知识，如病理性伤口愈合以及神经精神疾病。

The human body is composed of billions of cells. In order for the body to function properly these cells have to communicate with each other. They communicate by sending out signals that can be recognized by "antenna", which are called "receptors", on the surface of other cells. When a signal reaches a receptor, the receptor becomes activated, which stimulates cells to react and change their behaviour. The signal is stopped by removal of the activated receptors from the cell surface by uptake into vesicles, small compartments that are surrounded by a membrane. This process is called "endocytosis". Endocytosis is important for the normal functioning of our body but if it "goes wrong" it can lead to disease. For example, in the case of wound healing, upon injury, cells in the wound send out signals to attract other cells to repair the wound. When these "repair" cells receive the signal, they actively migrate to the wound to close it. When the process of endocytosis is not working properly in the repair cells, wound healing may be delayed and this may contribute to many diseases such as diabetic foot ulcers, venous leg ulcers, and pressure ulceration (decubitus) of immobilised patients. Especially, in an ageing population pathological wound healing becomes a major challenge. Cells send out signals by filling small vesicles inside the cell "X" with the compound that acts as a signal. The vesicle is then transported to the cell membrane of cell "X", the boundary of the cell with the outside world, and the content is released to the outside when the membrane of the vesicle fuses with the membrane of the cell "X". Nerve cells have many contacts with each other, called synapses, to relay signals to each other. This is the fundamental basis of how the brain works. At these synapses the vesicles with the stored signal is released to activate a neighbouring nerve cell "Y" by fusion of the vesicle with the membrane of the nerve cell "X". The signal is then diffusing to nerve cell "Y" where it activates receptors. Upon release of the signal the vesicle membrane has to be retrieved in order for the vesicle to be made again. The retrieval of the membrane is mediated again by endocytosis and is called synaptic vesicle recycling. Aberrant synaptic vesicle recycling impairs the communication of the nerve cells and this is thought to contribute to many neuropsychiatric diseases, which are major challenges to life long health and wellbeing such as epilepsy, depression, and schizophrenia. We propose to study the basic mechanisms of endocytosis of receptors and synaptic vesicle recycling using single cells cultured in the laboratory. We will analyze how cells normally control the uptake of receptors using biochemical approaches. We will also visualize individual proteins recruited to the vesicles by labeling them with a fluorescent dye. This will allow us to analyze the recruitment in living cells in real time using a microscope. Our study might permit us to uncover the role of the different proteins for the uptake of the receptors thereby explaining the mechanism of this fundamental biological process. We will also be using a microscope to make movies of cells migrating in a dish while exposed to signals from other cells. We will use this assay to uncover how endocytosis may contribute to the directed movement of cells to the signal as it would normally happen during wound healing. The outcome of the project will give novel insights into the normal function of individual cells within our body and in the long run may provide the knowledge for the development of targeted therapies for diseases with altered endocytosis such as pathological wound healing as well as neuropsychiatric diseases.