Biology subjects

Wright, N. J.

Publications and source records attributed to Wright, N. J..

3 recordsLinked to original sources

bioRxiv2026

No evidence for direct physical interaction of 5-HT2A-mGluR2 receptors in vitro or in vivo

Activation of mGluR2 (metabotropic glutamate receptor 2), the primary presynaptic autoreceptor for glutamate in the brain, is well established to attenuate the psychedelics-mediated behavioral and electrophysiological effects. However, the mechanisms responsible for these actions are controversial. The two competing mechanistic hypotheses have been proposed to explain this phenomenon are: (1) direct actions mediated by mGluR2/5-HT2A heterodimers, and (2) inhibition of 5-HT2A-mediated excitation of pyramidal neurons via presynaptic inhibition of glutamate release by mGluR2 receptors. Consistent with prior reports, we show that mGluR2 agonist pretreatment attenuates the head twitch response induced by the psychedelic drug 1-(2,5-Dimethoxy-4-iodophenyl)-2-aminopropane (DOI) in mice engineered to express mGluR2-mCherry and 5-HT2A-eGFP-CT tagged receptors. We next employed multiple orthogonal in vivo and in vitro approaches to explore the potential for direct physical interactions between mGluR2 and 5-HT2A receptors. Across all approaches, we found no evidence for receptor colocalization or oligomerization under basal or 5-HT2A agonist-exposed conditions in vitro or in vivo. Radioligand binding and kinetic analyses revealed no evidence for mGluR2-mediated modulation of 5-HT2A ligand binding in vitro or in vivo. Collectively, our findings support models in which mGluR2 signaling modulates the activity of Gq-coupled 5-HT2A receptors in layer V pyramidal neurons, rather than models positing the requirement of mGluR2/5-HT2A multimers.

neuroscience↗

bioRxiv2026

Cryo-EM Structures of Brain-Derived G Protein-Coupled Receptors: The First Direct Visualization from Mammalian Brain Tissue

Glutamate is the main excitatory neurotransmitter in the brain and mediates its actions by both ionotropic (e.g. NMDA and AMPA) and metabotropic glutamate receptors (mGluRs). The Groups II and III mGluRs, which pre-synaptically inhibit glutamate release, are important for synaptic plasticity, modulating neuronal excitation, learning and memory. Our current understanding of the structural organization and dynamics of these and other mGluRs, as well as most other GPCRs, relies mainly on studies using recombinant and highly engineered systems in vitro. Here, we combine CRISPR-mediated protein tagging, proteomics and a rapid immunoaffinity purification method to isolate endogenous mGluR2-containing assemblies from mouse brain and visualize them via cryo-EM. Analysis of the particle sets reveals the molecular structures of at least 11 distinct endogenous receptor assemblies that span active and inactive states, homomeric and heteromeric dimers, and G protein-coupled and uncoupled species. We find that mGluR2 homodimers and mGluR2/3 heterodimers are the major endogenous mGluR2-containing species present in the brain, with the mGluR2/3 heterodimers detected only in active state complexes, potentially reflecting basal activation of mGluR3 containing dimers by chloride. Reconstructing a comprehensive conformational equilibrium for the brain-isolated receptors in detergent reveals endogenous ternary complexes comprising mGluR2 homodimers and mGluR2/3 heterodimers with a single GoA heterotrimer which exhibit significant differences from prior studies with recombinant systems. Our work illuminates the endogenous conformational, proteomic and compositional landscape of the heterogenous mGluR2 complexes in the brain, thereby providing a structural framework for the pathophysiology of psychiatric disorders. This information has the potential to be leveraged for therapeutic targeting of endogenous glutamatergic signaling complexes.

neuroscience↗

bioRxiv2023

Molecular basis of polyspecific drug binding and transport by OCT1 and OCT2

A wide range of endogenous and xenobiotic organic ions require facilitated transport systems to cross the plasma membrane for their disposition1, 2. In mammals, organic cation transporter subtypes 1 and 2 (OCT1 and OCT2, also known as SLC22A1 and SLC22A2, respectively) are polyspecific transporters responsible for the uptake and clearance of structurally diverse cationic compounds in the liver and kidneys, respectively3, 4. Notably, it is well established that human OCT1 and OCT2 play central roles in the pharmacokinetics, pharmacodynamics, and drug-drug interactions (DDI) of many prescription medications, including metformin5, 6. Despite their importance, the basis of polyspecific cationic drug recognition and the alternating access mechanism for OCTs have remained a mystery. Here, we present four cryo-EM structures of apo, substrate-bound, and drug-bound OCT1 and OCT2 in outward-facing and outward-occluded states. Together with functional experiments, in silico docking, and molecular dynamics simulations, these structures uncover general principles of organic cation recognition by OCTs and illuminate unexpected features of the OCT alternating access mechanism. Our findings set the stage for a comprehensive structure-based understanding of OCT-mediated DDI, which will prove critical in the preclinical evaluation of emerging therapeutics.

biophysics↗