Identification of novel GLP-1 receptor interacting proteins

G蛋白偶联受体(GPCRs)是人体最大的一类蛋白质，几乎在所有哺乳动物细胞中都有表达。在细胞中，它们是来自其他细胞的化学信号的接收者，并充当细胞之间沟通和细胞反应的管道。目前GPCRs有5个亚类，包括B类受体，其中包括GLP1R。GLP-1受体最为人所知的是在制造和分泌胰岛素的胰腺β细胞以及调节食欲的大脑细胞中表达。在β细胞和大脑中，受体的化学信号是激素GLP-1。GLP-1主要在喂养过程中释放，并从肠道进入β细胞，刺激胰岛素分泌，从而降低血糖。在大脑中，GLP-1会引起饱腹感，减缓或抑制进一步的进食。目前对GLP1R和大多数GPCR还不太清楚的是，化学信号及其受体是如何促使细胞采取行动的，比如分泌胰岛素。这正是这笔赠款的目的。本提案的总体目标是在活细胞中使用一种新的蛋白质结合分析，以GLP1R作为我们的模型系统，用于识别和功能表征直接与GPCRs相互作用并调节GPCR活性的蛋白质。重要的是，我们提供了大量的初步数据，表明大脑中的GLP1R直接与一组新的蛋白质相互作用，这种相互作用取决于蛋白质，放大或抑制细胞反应。我们现在希望使用同样的策略来寻找能够将GLP1信号转导到胰岛素分泌的蛋白质(特别是在胰岛β细胞中)。一旦确定了这些蛋白质，我们将系统地确定它们如何与GLP1R相互作用，以及这种相互作用如何改变胰岛素分泌。我们特别寻找当它们与GLP1R相互作用时刺激胰岛素释放的蛋白质，因为它们可能是刺激胰岛素分泌的一种令人兴奋的新方式。

G protein-coupled receptors (GPCRs) are one of the body's largest class of proteins, being expressed in virtually every mammalian cell. In cells they are the receivers of chemical signals from other cells, and act as conduits for cell to cell communication and cellular responses. There are currently 5 subclasses of GPCRs, including the B-class receptors, which include the Glucagon-like peptide 1 receptor (GLP1R). GLP-1 receptors are are best known for being expressed in pancreatic beta-cells that make and secrete insulin and in cells in the brain that regulate appetite. In the beta-cell and in the brain, the chemical signal for the receptor is the hormone GLP-1. GLP-1 is primarily released during feeding and travels to the beta-cell from the intestine to stimulate insulin secretion, which lowers blood sugar. In the brain, GLP-1 causes a feeling of fullness, to slow or inhibit further feeding. What is currently not well understood for the GLP1R and for that matter most GPCRs, is how a chemical signal and its receptor cause the cell to take action, like to secrete insulin. That is precisely the purpose of this grant. The overall goal of the present proposal is to employ in living cells a novel protein binding assay developed to identify and functionally characterize proteins that directly interact with and modulate GPCR activity, using the GLP1R as our model system. Importantly, we provide substantial preliminary data that the GLP1R in the brain interacts with a new group of proteins directly and that this interaction, depending on the protein, amplifies or dampens the cellular response. We now wish to use this same strategy to find proteins (specifically in the pancreatic beta cell) that function to transduce the GLP1 signal to insulin secretion. Once these proteins are identified, we will systematically determine how they interact with the GLP1R and how this interaction changes insulin secretion. We are specifically looking for proteins that when they interact with GLP1R, stimulate insulin release because they may serve as an exciting new way to stimulate insulin secretion.