Excessive activation of the 1-amino-3-hydroxy-5-methyl-4-isoxazole propionate (AMPA) subtype of ionotropic glutamate receptors has been implicated as a leading contributor to a number of neurological diseases, such as epilepsy, stroke and amyotrophic lateral sclerosis (ALS). Using inhibitors as neuroprotective drugs to dampen the excessive receptor activity has been a long pursued therapeutic strategy. 2,3-Benzodiazepine derivatives, also known as GYKI compounds, are inhibitors of AMPA receptors, and they represent a class of the most promising drug candidates developed to date. However, the quantitative, functional activities of these compounds on AMPA receptors remain poorly defined. This is because AMPA receptors open their channels in the microsecond time domain and desensitize even in the millisecond time region. Yet, current kinetic techniques do not have sufficient time resolutions required to characterize the kinetic mechanism of channel opening and the mechanism of inhibitor/drug- receptor interaction. In this proposal, we will systematically elucidate the mechanism of action for a series of 19 GYKI compounds, measure their potency on specific AMPA receptor subunits, and characterize the structure-activity relationship, including the number of inhibitory sites on a receptor and whether any two sites interact with each other (i.e., the binding of two inhibitors to their sites can be independent or negatively affected by binding of either one first). To achieve the specific aims, we will carry out a number of experiments, including a laser- pulse photolysis study with the ?s time resolution to investigate the effect of a GYKI compound on the channel-opening rate process of an AMPA receptor. The kinetic investigation of these compounds, relevant to the time scale within which all receptor forms are still functional, has not been previously possible. Our results on the receptor properties and the structure-activity relationship of these compounds will be valuable for rational design and synthesis of subunit- and conformation-selective GYKI compounds with higher potency so that AMPA receptor activities can be controlled more quantitatively.
We propose to systematically characterize a group of GYKI compounds, which are inhibitors on AMPA glutamate ion channel receptors. These compounds are candidates for developing potential drugs to treat a number of neurological diseases involving AMPA receptors.
|Jaremko, William J; Huang, Zhen; Wen, Wei et al. (2017) Identification and characterization of RNA aptamers: A long aptamer blocks the AMPA receptor and a short aptamer blocks both AMPA and kainate receptors. J Biol Chem 292:7338-7347|
|Wen, Wei; Lin, Chi-Yen; Niu, Li (2017) R/G editing in GluA2Rflop modulates the functional difference between GluA1 flip and flop variants in GluA1/2R heteromeric channels. Sci Rep 7:13654|
|Jaremko, William J; Huang, Zhen; Wen, Wei et al. (2017) One aptamer, two functions: the full-length aptamer inhibits AMPA receptors, while the short one inhibits both AMPA and kainate receptors. RNA Dis 4:|
|Wang, Congzhou; Wu, Andrew; Shen, Yu-Chuan et al. (2015) Mechanism and site of inhibition of AMPA receptors: substitution of one and two methyl groups at the 4-aminophenyl ring of 2,3-benzodiazepine and implications in the ""E"" site. ACS Chem Neurosci 6:1371-8|
|Lin, Chi-Yen; Huang, Zhen; Wen, Wei et al. (2015) Enhancing Protein Expression in HEK-293 Cells by Lowering Culture Temperature. PLoS One 10:e0123562|
|Niu, Li (2015) Mechanism-based design of 2,3-benzodiazepine inhibitors for AMPA receptors. Acta Pharm Sin B 5:500-5|
|Niu, Li (2014) AMPA receptor inhibitors for the treatment of neurological disorders. Future Med Chem 6:849-952|
|Lin, Chi-Yen; Huang, Zhen; Jaremko, William et al. (2014) High-performance liquid chromatography purification of chemically modified RNA aptamers. Anal Biochem 449:106-8|
|Wang, Congzhou; Han, Yan; Wu, Andrew et al. (2014) Mechanism and site of inhibition of AMPA receptors: pairing a thiadiazole with a 2,3-benzodiazepine scaffold. ACS Chem Neurosci 5:138-47|
|Wu, Andrew; Wang, Congzhou; Niu, Li (2014) Mechanism of inhibition of the GluA1 AMPA receptor channel opening by the 2,3-benzodiazepine compound GYKI 52466 and a N-methyl-carbamoyl derivative. Biochemistry 53:3033-41|
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