| 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] CCG2_RAT Regulates the trafficking and gating properties of AMPA-selective glutamate receptors (AMPARs). Promotes their targeting to the cell membrane and synapses and modulates their gating properties by slowing their rates of activation, deactivation and desensitization. Does not show subunit-specific AMPA receptor regulation and regulates all AMPAR subunits. Thought to stabilize the calcium channel in an inactivated (closed) state.[15] [16] [17] [18] [19]
Publication Abstract from PubMed
Designing safe and effective oligonucleotide (ON) therapeutics requires thorough understanding of structural-activity relationship (SAR) with the intended on-target(s) as well as the unintended off-target(s). Despite encouraging pharmacodynamic activity in a Phase 1b study, development of the first-generation anti-miR-17 ON RGLS4326 for the treatment of autosomal dominant polycystic kidney disease was discontinued due to dose-limiting central nervous system (CNS)-related toxicity observed in nonclinical chronic toxicity studies. Here, we provide SAR evidence that the nucleobase guanine at the 3'-terminus of RGLS4326 drives an unexpected off-target aptamer-like direct interaction with alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR), thereby causing CNS toxicity. By replacing the 3'-terminal guanine with adenine, we discover the next-generation anti-miR-17 RGLS8429 that is devoid of off-target AMPAR interaction and CNS toxicity while preserving the potency against the on-target miR-17. Here, we show a way to avoid off-target CNS effects and, more importantly, data that support the clinical development of RGLS8429.
The nucleobase guanine at the 3'-terminus of oligonucleotide RGLS4326 drives off-target AMPAR inhibition and CNS toxicity.,Valencia T, Yen LY, Berman C, Vincent T, Davis S, Varrone F, Huang J, Mastroianni J, Carlson M, Owen T, Kamel A, Drygin D, Kinberger GA, Gangwar SP, Yelshanskaya MV, Ridley J, Kirby R, Alvarez J, Lakhia R, Patel V, Sobolevsky AI, Lee EC Nat Commun. 2025 Nov 28;16(1):10762. doi: 10.1038/s41467-025-65799-5. PMID:41315228[20]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
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- ↑ 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
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- ↑ 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
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- ↑ 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:https://dx.doi.org/10.1073/pnas.1037393100
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- ↑ 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
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- ↑ Milstein AD, Zhou W, Karimzadegan S, Bredt DS, Nicoll RA. TARP subtypes differentially and dose-dependently control synaptic AMPA receptor gating. Neuron. 2007 Sep 20;55(6):905-18. PMID:17880894 doi:https://dx.doi.org/10.1016/j.neuron.2007.08.022
- ↑ Kato AS, Siuda ER, Nisenbaum ES, Bredt DS. AMPA receptor subunit-specific regulation by a distinct family of type II TARPs. Neuron. 2008 Sep 25;59(6):986-96. doi: 10.1016/j.neuron.2008.07.034. PMID:18817736 doi:https://dx.doi.org/10.1016/j.neuron.2008.07.034
- ↑ Soto D, Coombs ID, Renzi M, Zonouzi M, Farrant M, Cull-Candy SG. Selective regulation of long-form calcium-permeable AMPA receptors by an atypical TARP, gamma-5. Nat Neurosci. 2009 Mar;12(3):277-85. doi: 10.1038/nn.2266. Epub 2009 Feb 22. PMID:19234459 doi:https://dx.doi.org/10.1038/nn.2266
- ↑ 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
- ↑ Shi Y, Suh YH, Milstein AD, Isozaki K, Schmid SM, Roche KW, Nicoll RA. Functional comparison of the effects of TARPs and cornichons on AMPA receptor trafficking and gating. Proc Natl Acad Sci U S A. 2010 Sep 14;107(37):16315-9. doi:, 10.1073/pnas.1011706107. Epub 2010 Aug 30. PMID:20805473 doi:https://dx.doi.org/10.1073/pnas.1011706107
- ↑ Valencia T, Yen LY, Berman C, Vincent T, Davis S, Varrone F, Huang J, Mastroianni J, Carlson M, Owen T, Kamel A, Drygin D, Kinberger GA, Gangwar SP, Yelshanskaya MV, Ridley J, Kirby R, Alvarez J, Lakhia R, Patel V, Sobolevsky AI, Lee EC. The nucleobase guanine at the 3'-terminus of oligonucleotide RGLS4326 drives off-target AMPAR inhibition and CNS toxicity. Nat Commun. 2025 Nov 28;16(1):10762. PMID:41315228 doi:10.1038/s41467-025-65799-5
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