Cross-signaling in metabotropic glutamate 2 and serotonin 2A receptor heteromers in mammalian cells
Lia Baki, M. Fribourg, Jason Younkin, Jose M. Eltit, J. Moreno, Gyu Park, Zhanna V. Vysotskaya, Adishesh K. Narahari, Stuart C. Sealfon, Javier González-Maeso, D. Logothetis
Pflügers Archiv: European Journal of Physiology January 16, 2016 DOI: 10.1007/s00424-015-1780-7 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | In vitro cell study Peer reviewed |
|---|---|
| Population | HEK293 cells stably co-expressing mGlu2R, 5-HT2AR, and GIRK1/GIRK4 channels |
| Interventions | LY341495 5-HT |
| Measures | Fura-2 calcium imaging, GIRK channel reporter (whole-cell patch-clamp and potentiometric dye fluorescence assays), competition binding assays |
| Topics | Serotonin |
| Key points | The mGlu2 and 5-HT2A receptors cross-signaled in only 25–30% of stably co-expressed HEK293 cell clones. Crosstalk-positive clones showed increased receptor colocalization at the cell surface, lower mGlu2R and higher 2AR binding-site densities, and higher mGlu2R/2AR surface expression ratios, and a ligand combination could induce crosstalk in a crosstalk-negative clone. |
Abstract
We previously reported that co-expression of the Gi-coupled metabotropic glutamate receptor 2 (mGlu2R) and the Gq-coupled serotonin (5-HT) 2A receptor (2AR) in Xenopus oocytes (Fribourg et al. Cell 147:1011–1023, 2011) results in inverse cross-signaling, where for either receptor, strong agonists suppress and inverse agonists potentiate the signaling of the partner receptor. Importantly, through this cross-signaling, the mGlu2R/2AR heteromer integrates the actions of psychedelic and antipsychotic drugs. To investigate whether mGlu2R and 2AR can cross-signal in mammalian cells, we stably co-expressed them in HEK293 cells along with the GIRK1/GIRK4 channel, a reporter of Gi and Gq signaling activity. Crosstalk-positive clones were identified by Fura-2 calcium imaging, based on potentiation of 5-HT-induced Ca2+ responses by the inverse mGlu2/3R agonist LY341495. Cross-signaling from both sides of the complex was confirmed in representative clones by using the GIRK channel reporter, both in whole-cell patch-clamp and in fluorescence assays using potentiometric dyes, and further established by competition binding assays. Notably, only 25–30 % of the clones were crosstalk-positive. The crosstalk-positive phenotype correlated with (a) increased colocalization of the two receptors at the cell surface, (b) lower density of mGlu2R binding sites and higher density of 2AR binding sites in total membrane preparations, and (c) higher ratios of mGlu2R/2AR normalized surface protein expression. Consistent with our results in Xenopus oocytes, a combination of ligands targeting both receptors could elicit functional crosstalk in a crosstalk-negative clone. Crosstalk-positive clones can be used in high-throughput assays for identification of antipsychotic drugs targeting this receptor heterocomplex.
Comparable studies
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| Study | Year | Design | Participants |
|---|---|---|---|
| Psilocybin induces rapid and persistent growth of dendritic spines in frontal cortex in vivo Mice | 2021 | Observational cohort | |
| Neurotoxicity of the psychedelic amphetamine, methylenedioxymethamphetamine. Rats (implied by typical neurochemical study context) | 1987 | Experimental study | |
| Psychedelics promote neuroplasticity through the activation of intracellular 5-HT2A receptors In vitro and in vivo (rodent) models | 2023 | Experimental study | |
| 3,4-Methylenedioxymethamphetamine and 3,4-methylenedioxyamphetamine destroy serotonin terminals in rat brain: quantification of neurodegeneration by measurement of [3H]paroxetine-labeled serotonin uptake sites. Rat brain | 1987 | Animal experiment | |
| Comparison of the monoamine transporters from human and mouse in their sensitivities to psychostimulant drugs Human and mouse dopamine, norepinephrine, and serotonin transporters expressed in cells | 2006 | In vitro laboratory study |
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