| Structural highlights
Function
GRIA2_RAT Receptor for glutamate that functions as ligand-gated ion channel in the central nervous system and plays an important role in excitatory synaptic transmission. L-glutamate acts as an excitatory neurotransmitter at many synapses in the central nervous system. Binding of the excitatory neurotransmitter L-glutamate induces a conformation change, leading to the opening of the cation channel, and thereby converts the chemical signal to an electrical impulse. The receptor then desensitizes rapidly and enters a transient inactive state, characterized by the presence of bound agonist. In the presence of CACNG4 or CACNG7 or CACNG8, shows resensitization which is characterized by a delayed accumulation of current flux upon continued application of glutamate.[1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]
Publication Abstract from PubMed
AMPA glutamate receptors (AMPARs) mediate excitatory neurotransmission throughout the brain. Their signalling is uniquely diversified by brain region-specific auxiliary subunits, providing an opportunity for the development of selective therapeutics. AMPARs associated with TARP gamma8 are enriched in the hippocampus, and are targets of emerging anti-epileptic drugs. To understand their therapeutic activity, we determined cryo-EM structures of the GluA1/2-gamma8 receptor associated with three potent, chemically diverse ligands. We find that despite sharing a lipid-exposed and water-accessible binding pocket, drug action is differentially affected by binding-site mutants. Together with patch-clamp recordings and MD simulations we also demonstrate that ligand-triggered reorganisation of the AMPAR-TARP interface contributes to modulation. Unexpectedly, one ligand (JNJ-61432059) acts bifunctionally, negatively affecting GluA1 but exerting positive modulatory action on GluA2-containing AMPARs, in a TARP stoichiometry-dependent manner. These results further illuminate the action of TARPs, demonstrate the sensitive balance between positive and negative modulatory action, and provide a mechanistic platform for development of both positive and negative selective AMPAR modulators.
Modulatory mechanisms of TARP gamma8-selective AMPA receptor therapeutics.,Zhang D, Lape R, Shaikh SA, Kohegyi BK, Watson JF, Cais O, Nakagawa T, Greger IH Nat Commun. 2023 Mar 25;14(1):1659. doi: 10.1038/s41467-023-37259-5. PMID:36966141[15]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Everts I, Villmann C, Hollmann M. N-Glycosylation is not a prerequisite for glutamate receptor function but Is essential for lectin modulation. Mol Pharmacol. 1997 Nov;52(5):861-73. PMID:9351977
- ↑ Schwenk J, Harmel N, Zolles G, Bildl W, Kulik A, Heimrich B, Chisaka O, Jonas P, Schulte U, Fakler B, Klocker N. Functional proteomics identify cornichon proteins as auxiliary subunits of AMPA receptors. Science. 2009 Mar 6;323(5919):1313-9. doi: 10.1126/science.1167852. PMID:19265014 doi:10.1126/science.1167852
- ↑ Kato AS, Gill MB, Ho MT, Yu H, Tu Y, Siuda ER, Wang H, Qian YW, Nisenbaum ES, Tomita S, Bredt DS. Hippocampal AMPA receptor gating controlled by both TARP and cornichon proteins. Neuron. 2010 Dec 22;68(6):1082-96. doi: 10.1016/j.neuron.2010.11.026. PMID:21172611 doi:10.1016/j.neuron.2010.11.026
- ↑ Jin R, Horning M, Mayer ML, Gouaux E. Mechanism of activation and selectivity in a ligand-gated ion channel: structural and functional studies of GluR2 and quisqualate. Biochemistry. 2002 Dec 31;41(52):15635-43. PMID:12501192
- ↑ Sun Y, Olson R, Horning M, Armstrong N, Mayer M, Gouaux E. Mechanism of glutamate receptor desensitization. Nature. 2002 May 16;417(6886):245-53. PMID:12015593 doi:10.1038/417245a
- ↑ Jin R, Banke TG, Mayer ML, Traynelis SF, Gouaux E. Structural basis for partial agonist action at ionotropic glutamate receptors. Nat Neurosci. 2003 Aug;6(8):803-10. PMID:12872125 doi:10.1038/nn1091
- ↑ Armstrong N, Mayer M, Gouaux E. Tuning activation of the AMPA-sensitive GluR2 ion channel by genetic adjustment of agonist-induced conformational changes. Proc Natl Acad Sci U S A. 2003 May 13;100(10):5736-41. Epub 2003 May 2. PMID:12730367 doi:http://dx.doi.org/10.1073/pnas.1037393100
- ↑ Jin R, Clark S, Weeks AM, Dudman JT, Gouaux E, Partin KM. Mechanism of positive allosteric modulators acting on AMPA receptors. J Neurosci. 2005 Sep 28;25(39):9027-36. PMID:16192394 doi:25/39/9027
- ↑ Frandsen A, Pickering DS, Vestergaard B, Kasper C, Nielsen BB, Greenwood JR, Campiani G, Fattorusso C, Gajhede M, Schousboe A, Kastrup JS. Tyr702 is an important determinant of agonist binding and domain closure of the ligand-binding core of GluR2. Mol Pharmacol. 2005 Mar;67(3):703-13. Epub 2004 Dec 9. PMID:15591246 doi:10.1124/mol.104.002931
- ↑ Armstrong N, Jasti J, Beich-Frandsen M, Gouaux E. Measurement of conformational changes accompanying desensitization in an ionotropic glutamate receptor. Cell. 2006 Oct 6;127(1):85-97. PMID:17018279 doi:10.1016/j.cell.2006.08.037
- ↑ Kasper C, Pickering DS, Mirza O, Olsen L, Kristensen AS, Greenwood JR, Liljefors T, Schousboe A, Watjen F, Gajhede M, Sigurskjold BW, Kastrup JS. The structure of a mixed GluR2 ligand-binding core dimer in complex with (S)-glutamate and the antagonist (S)-NS1209. J Mol Biol. 2006 Apr 7;357(4):1184-201. Epub 2006 Jan 31. PMID:16483599 doi:10.1016/j.jmb.2006.01.024
- ↑ Sobolevsky AI, Rosconi MP, Gouaux E. X-ray structure, symmetry and mechanism of an AMPA-subtype glutamate receptor. Nature. 2009 Dec 10;462(7274):745-56. Epub . PMID:19946266 doi:10.1038/nature08624
- ↑ Rossmann M, Sukumaran M, Penn AC, Veprintsev DB, Babu MM, Greger IH. Subunit-selective N-terminal domain associations organize the formation of AMPA receptor heteromers. EMBO J. 2011 Mar 2;30(5):959-71. Epub 2011 Feb 11. PMID:21317873 doi:10.1038/emboj.2011.16
- ↑ Ahmed AH, Wang S, Chuang HH, Oswald RE. Mechanism of AMPA receptor activation by partial agonists: disulfide trapping of closed lobe conformations. J Biol Chem. 2011 Aug 16. PMID:21846932 doi:10.1074/jbc.M111.269001
- ↑ Zhang D, Lape R, Shaikh SA, Kohegyi BK, Watson JF, Cais O, Nakagawa T, Greger IH. Modulatory mechanisms of TARP γ8-selective AMPA receptor therapeutics. Nat Commun. 2023 Mar 25;14(1):1659. PMID:36966141 doi:10.1038/s41467-023-37259-5
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