The role of a calcium permeable TRP channel in endocytosis

 描述(申请人提供)：突触小泡胞吐是调节大脑功能的一个基本过程；随后的突触小泡吞噬对维持突触传递很重要。由于突触囊泡内吞功能异常与帕金森氏病、癫痫和阿尔茨海默病等人类疾病有关，阐明突触囊泡内吞的分子机制不仅对了解神经元功能具有重要意义，而且将为开发治疗脑部疾病的新疗法提供潜在的靶点。虽然钙离子对胞吐作用是至关重要的，但越来越多的证据表明，钙离子对胞吞作用也可能是重要的。虽然细胞外钙离子内流对细胞内吞作用的重要性已被接受，但内吞作用的钙离子内流途径尚不清楚，因为可能涉及电压门控钙离子通道以外的钙离子通透通道。瞬时受体电位通道是一类在脑内高表达的非选择性阳离子通道。Trp Melastatin 7(TRPM7)是Trp超家族的一员，是一种钙离子通透通道。我们推测，位于胞内小泡上的钙离子通透性的TRPM7作为钙离子内流途径调节内吞作用。我们的假设得到了这项提案中描述的初步数据的很好支持。我们将使用嗜铬细胞和神经元中的生物物理和活细胞成像分析来验证这一假说，以衡量分子生物学操作的结果，例如转基因TRPM7基因敲除动物模型和shRNA介导的基因敲除。

 DESCRIPTION (provided by applicant): Synaptic vesicle exocytosis is a fundamental process mediating brain function; subsequent synaptic vesicle endocytosis is important to maintain synaptic transmission. Since malfunctions in synaptic vesicle endocytosis have been linked to human diseases, such as Parkinson's disease, epilepsy, and Alzheimer's disease, elucidating the molecular mechanisms for synaptic vesicle endocytosis will have implications not only for understanding neuronal function but also will provide potential targets for developing novel therapies to treat brain diseases. While it is well established that Ca2+ is critical for exocytosi, increasing evidence suggests that Ca2+ may also be important for endocytosis. Although the importance for endocytosis of Ca2+ influx from extracellular space is accepted, the identity of the Ca2+ influx route for endocytosis remains unclear, as Ca2+-permeable channels other than voltage-gated Ca2+ channels may be involved. Transient receptor potential (TRP) channels are a family of non-selective cation channels with high expression levels in the brain. TRP melastatin 7 (TRPM7), a member of the TRP superfamily, is a Ca2+- permeable channel. We hypothesize that the Ca2+-permeable TRPM7, located on endocytic vesicles, acts as the Ca2+ influx route to regulate endocytosis. Our hypothesis is well supported by the preliminary data described in this proposal. We will test this hypothesis using biophysical and live-cell imaging assays in chromaffin cells and neurons to measure the outcome of molecular biological manipulations such as transgenetic TRPM7 knockout animal models and shRNA-mediated gene knockdown.