3-aminobutyric acid (GABA)-gated chloride channels (GABAA and GABAC receptors) play important roles in fast synaptic inhibition in the mammalian brain. They are also the major targets of many clinically useful neuroactive compounds. Dysfunction of these GABA-gated ion channels can result in epilepsy and other neural disorders. Binding of GABA to its receptor is thought to initiate a conformational wave starting from the binding site(s) and propagating to the gating machinery to open the pore. Gaining insights into the dynamic structural basis of these conformational rearrangements therefore is the key step to understanding the mechanism of GABA receptor activation and antagonism. However, despite intensive structure-function relationship studies in the past, structural dynamics underlying GABA receptor activation is still not fully understood. This project seeks to provide new insights into structural bases for GABAC receptor function by employing techniques successfully adapted in this laboratory.
The first aim i s to use site-specific fluorescence combined with substituted cysteine accessibility analysis and electrophysiological recording to define agonist-induced structural rearrangements in the subunit interface underlying channel activation.
The second aim i s to use fluorescence resonance energy transfer (FRET) to detect conformational changes not located in subunit interface and to deduce their moving direction during receptor activation.
The third aim i s to use site-specific fluorescence and FRET to define agonist-induced movements antagonizable by noncompetitive antagonists.
The fourth aim i s to validate the functional significance of the moving residues identified by previous aims by single channel analysis and explore coupling mechanism by mutant cycle analysis. Collectively, this work will allow us to detect conformational changes in and out of subunit interface underlying GABA receptor activation and antagonism. These studies will test the project's central hypothesis that GABA receptor activation involves an agonist-induced rotation of the N-terminal domain, which then propagates to the gating machinery to open the pore. Insights gained from this work will illuminate mechanisms of receptor activation and antagonism that have potential applicability more generally to the entire class of ligand-gated ion channels. The findings also will provide a structural basis for development of new therapeutics or research tools targeting GABA receptors.
This project seeks to provide new insights into structural basis for the mechanism of GABA receptor function by employing techniques successfully adapted in this laboratory. The findings will be fundamental to understanding the pathological processes of GABA receptor dysfunction and the mechanism of action for those drugs targeting GABA receptors. The findings will also provide a structural basis for development of new therapeutics or research tools targeting GABA receptors.
|Xu, Xiaojun; Sepich, Caraline; Lukas, Ronald J et al. (2016) Emamectin is a non-selective allosteric activator of nicotinic acetylcholine receptors and GABAA/C receptors. Biochem Biophys Res Commun 473:795-800|
|Xu, Xiao-Jun; Roberts, Diane; Zhu, Guo-Nian et al. (2016) Competitive antagonists facilitate the recovery from desensitization of Î±1Î²2Î³2 GABAA receptors expressed in Xenopus oocytes. Acta Pharmacol Sin 37:1020-30|
|Zhang, Qinhui; Du, Yingjie; Zhang, Jianliang et al. (2015) Functional Impact of 14 Single Nucleotide Polymorphisms Causing Missense Mutations of Human Î±7 Nicotinic Receptor. PLoS One 10:e0137588|
|Semaan, Suzan; Wu, Jie; Gan, Yan et al. (2015) Hyperactivation of BDNF-TrkB signaling cascades in human hypothalamic hamartoma (HH): a potential mechanism contributing to epileptogenesis. CNS Neurosci Ther 21:164-72|
|Yan, Hongxia; Pan, Na; Xue, Fenqin et al. (2015) The coupling interface and pore domain codetermine the single-channel activity of the Î±7 nicotinic receptor. Neuropharmacology 95:448-58|
|Huang, Yao; Chang, Yongchang (2014) Regulation of pancreatic islet beta-cell mass by growth factor and hormone signaling. Prog Mol Biol Transl Sci 121:321-49|
|Eaton, J Brek; Lucero, Linda M; Stratton, Harrison et al. (2014) The unique *4+/-*4 agonist binding site in (*4)3(*2)2 subtype nicotinic acetylcholine receptors permits differential agonist desensitization pharmacology versus the (*4)2(*2)3 subtype. J Pharmacol Exp Ther 348:46-58|
|Zhao, Run-Zhen; Nie, Hong-Guang; Su, Xue-Feng et al. (2012) Characterization of a novel splice variant of Î´ ENaC subunit in human lungs. Am J Physiol Lung Cell Mol Physiol 302:L1262-72|
|Lu, Jia; Li, Chaokun; Shi, Chunwei et al. (2012) Identification of novel splice variants and exons of human endothelial cell-specific chemotaxic regulator (ECSCR) by bioinformatics analysis. Comput Biol Chem 41:41-50|
|Wu, Wen; Shi, Chunwei; Ma, Fanxin et al. (2012) Structural and Functional Characterization of Two Alternative Splicing Variants of Mouse Endothelial Cell-Specific Chemotaxis Regulator (ECSCR). Int J Mol Sci 13:4920-36|
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