The role of a calcium permeable TRP channel in endocytosis

 描述（由申请人提供）：突触囊泡胞吐作用是介导脑功能的基本过程;随后的突触囊泡胞吞作用对于维持突触传递是重要的。由于突触囊泡内吞功能障碍与帕金森病、癫痫和阿尔茨海默病等人类疾病有关，因此阐明突触囊泡内吞的分子机制不仅对理解神经元功能具有重要意义，而且还将为开发治疗脑疾病的新疗法提供潜在靶点。虽然已经确定Ca 2+对于胞吐是关键的，但是越来越多的证据表明Ca 2+对于胞吞也可能是重要的。虽然从细胞外空间的Ca 2+内流的内吞作用的重要性被接受，但内吞作用的Ca 2+内流途径的身份仍不清楚，因为可能涉及电压门控Ca 2+通道以外的Ca 2+渗透通道。瞬时受体电位（TRP）通道是一个在脑中高表达水平的非选择性阳离子通道家族。TRP melastatin 7（TRPM 7）是TRP超家族的成员，是一种Ca 2+渗透通道。我们推测，Ca 2+渗透TRPM 7，位于内吞囊泡，作为Ca 2+内流途径调节内吞作用。我们的假设得到了本提案中描述的初步数据的充分支持。我们将在嗜铬细胞和神经元中使用生物物理和活细胞成像分析来测试这一假设，以测量分子生物学操作的结果，例如转基因TRPM 7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.