NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin
ABSTRACT Transient receptor potential melastatin‐4 (TRPM4) forms a complex with N‐methyl‐D‐aspartate receptors (NMDARs) that facilitates NMDAR‐mediated neurotoxicity. Here we used pharmacological tools to determine how TRPM4 regulates NMDAR signaling. Brophenexin, a compound that binds to TRPM4 at t...
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2024-12-01
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| Online Access: | https://doi.org/10.1002/prp2.70038 |
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| author | Jordan Casby Benjamin M. Gansemer Stanley A. Thayer |
| author_facet | Jordan Casby Benjamin M. Gansemer Stanley A. Thayer |
| author_sort | Jordan Casby |
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| description | ABSTRACT Transient receptor potential melastatin‐4 (TRPM4) forms a complex with N‐methyl‐D‐aspartate receptors (NMDARs) that facilitates NMDAR‐mediated neurotoxicity. Here we used pharmacological tools to determine how TRPM4 regulates NMDAR signaling. Brophenexin, a compound that binds to TRPM4 at the NMDAR binding interface, protected hippocampal neurons in culture from NMDA‐induced death, consistent with published work. Brophenexin (10 μM) reduced NMDA‐evoked whole‐cell currents recorded at 22°C by 87% ± 14% with intracellular Ca2+ chelated to prevent TRPM4 activation. Brophenexin inhibited NMDA‐evoked currents recorded in Na+‐free solution by 87% ± 13%, suggesting that brophenexin and TRPM4 modulate NMDAR function. Incubating cultures in Mg2+‐free buffer containing tetrodotoxin, 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione, and bicuculline for 30 min inhibited NMDA‐evoked increases in intracellular Ca2+ concentration ([Ca2+]i) recorded at 22°C by 50% ± 18% and prevented inhibition by brophenexin. In the absence of these inhibitors, brophenexin inhibited the NMDA‐evoked response by 51% ± 16%. Treatment with the TRPM4 inhibitor 4‐chloro‐2‐(1‐naphthyloxyacetamido)benzoic acid (NBA; 10 μM) increased NMDA‐evoked Ca2+ influx by 90% ± 15%. Increasing extracellular NaCl to 237 mM, a treatment that activates TRPM4, inhibited the NMDA‐evoked increase in [Ca2+]i by a process that occluded the inhibition produced by brophenexin and was prevented by NBA. In recordings performed at 32°C–34°C, brophenexin inhibited the NMDA‐evoked [Ca2+]i response by 42% ± 10% but NBA was without effect. These results are consistent with a model in which TRPM4 interacts with NMDARs to potentiate Ca2+ flux through the NMDAR ion channel and thus provides a potential mechanism for the neuroprotection afforded by NMDAR/TRPM4 interface inhibitors such as brophenexin. |
| format | Article |
| id | doaj-art-ed544a7d321d49609d3b805ccee06cef |
| institution | DOAJ |
| issn | 2052-1707 |
| language | English |
| publishDate | 2024-12-01 |
| publisher | Wiley |
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| spelling | doaj-art-ed544a7d321d49609d3b805ccee06cef2025-08-20T02:50:30ZengWileyPharmacology Research & Perspectives2052-17072024-12-01126n/an/a10.1002/prp2.70038NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor BrophenexinJordan Casby0Benjamin M. Gansemer1Stanley A. Thayer2Department of Pharmacology University of Minnesota Medical School Minneapolis Minnesota USADepartment of Pharmacology University of Minnesota Medical School Minneapolis Minnesota USADepartment of Pharmacology University of Minnesota Medical School Minneapolis Minnesota USAABSTRACT Transient receptor potential melastatin‐4 (TRPM4) forms a complex with N‐methyl‐D‐aspartate receptors (NMDARs) that facilitates NMDAR‐mediated neurotoxicity. Here we used pharmacological tools to determine how TRPM4 regulates NMDAR signaling. Brophenexin, a compound that binds to TRPM4 at the NMDAR binding interface, protected hippocampal neurons in culture from NMDA‐induced death, consistent with published work. Brophenexin (10 μM) reduced NMDA‐evoked whole‐cell currents recorded at 22°C by 87% ± 14% with intracellular Ca2+ chelated to prevent TRPM4 activation. Brophenexin inhibited NMDA‐evoked currents recorded in Na+‐free solution by 87% ± 13%, suggesting that brophenexin and TRPM4 modulate NMDAR function. Incubating cultures in Mg2+‐free buffer containing tetrodotoxin, 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione, and bicuculline for 30 min inhibited NMDA‐evoked increases in intracellular Ca2+ concentration ([Ca2+]i) recorded at 22°C by 50% ± 18% and prevented inhibition by brophenexin. In the absence of these inhibitors, brophenexin inhibited the NMDA‐evoked response by 51% ± 16%. Treatment with the TRPM4 inhibitor 4‐chloro‐2‐(1‐naphthyloxyacetamido)benzoic acid (NBA; 10 μM) increased NMDA‐evoked Ca2+ influx by 90% ± 15%. Increasing extracellular NaCl to 237 mM, a treatment that activates TRPM4, inhibited the NMDA‐evoked increase in [Ca2+]i by a process that occluded the inhibition produced by brophenexin and was prevented by NBA. In recordings performed at 32°C–34°C, brophenexin inhibited the NMDA‐evoked [Ca2+]i response by 42% ± 10% but NBA was without effect. These results are consistent with a model in which TRPM4 interacts with NMDARs to potentiate Ca2+ flux through the NMDAR ion channel and thus provides a potential mechanism for the neuroprotection afforded by NMDAR/TRPM4 interface inhibitors such as brophenexin.https://doi.org/10.1002/prp2.70038brophenexinCa2+ signalingexcitotoxicityNMDARTRPM4 |
| spellingShingle | Jordan Casby Benjamin M. Gansemer Stanley A. Thayer NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin Pharmacology Research & Perspectives brophenexin Ca2+ signaling excitotoxicity NMDAR TRPM4 |
| title | NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin |
| title_full | NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin |
| title_fullStr | NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin |
| title_full_unstemmed | NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin |
| title_short | NMDA Receptor–Mediated Ca2+ Flux Attenuated by the NMDA Receptor/TRPM4 Interface Inhibitor Brophenexin |
| title_sort | nmda receptor mediated ca2 flux attenuated by the nmda receptor trpm4 interface inhibitor brophenexin |
| topic | brophenexin Ca2+ signaling excitotoxicity NMDAR TRPM4 |
| url | https://doi.org/10.1002/prp2.70038 |
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