Functional and Pharmacological Implications of mGluR Heteromerization

描述（由申请人提供）：G蛋白偶联受体（gpcr）是临床治疗中最常见的靶向蛋白家族。GPCRs之间的分子相互作用对它们的功能和靶向药物的作用有深远的影响。我们研究了两种谷氨酸激活的GPCRs mGluR1和mGluR5之间相互作用的功能和药理作用，已知它们形成同型二聚体复合物（mGluR1-mGluR1和mGluR5-mGluR5二聚体），参与许多病理生理过程，并在中枢神经系统中广泛分布。我们的数据表明，这些受体可以在功能上相互作用，这种相互作用改变了它们的

DESCRIPTION (provided by applicant): G protein coupled receptors (GPCRs) are the most frequently targeted protein family in clinical therapeutics. The molecular interactions between GPCRs can have a profound impact on their function and on the effects of drugs that target them. We examined the functional and pharmacological effects of interactions between two glutamate-activated GPCRs called mGluR1 and mGluR5, which are known to form homodimeric complexes (mGluR1-mGluR1 and mGluR5-mGluR5 dimers), are involved in many patho-physiological processes, and have widespread distribution in the central nervous system. Our data suggest that these receptors can interact functionally, and that this interaction alters their sensitivity to selective pharmacological agents that target them. We suggest a novel hypothesis to explain this interaction in which mGluR1 and mGluR5 dimers combine to form tetrameric (or possibly larger) complexes with the ability to trans-activate, such that ligand binding to one receptor may activate G protein through the other. Further, these putative tetrameric receptors seem to respond to some pharmacological agents differently than their homodimeric constituents. To address this hypothesis, we will pursue the following Specific Aims: 1) To characterize the unique pharmacological properties of mGluR1/5 heteromers using the rat superior cervical ganglion (SCG) neuronal expression system, 2) To confirm the pharmacological and signaling properties of mGluR1/5 heteromers by expression in HeLa cells and using a different effectors to assay receptor signaling, 3) To directly assess the ability of fluorescently-tagged mGluR1, mGluR5 and both receptors together to form dimeric, tetrameric, or higher order multimeric receptors using multi-photon Fluorescence Recovery After Photobleaching (FRAP) and Fluorescence Correlation Spectroscopy (FCS), and 4) To verify the physiological relevance of functional mGluR interactions in neurons that natively express both mGluR1 and mGluR5.