Biology subjects

Spangler, C. J.

Publications and source records attributed to Spangler, C. J..

3 recordsLinked to original sources

bioRxiv2026

Mapping AMPA and NMDA receptors at mouse brain hippocampal synapses by cryo-ET

AMPA and NMDA receptors are fundamental to synaptic transmission through the detection of released neurotransmitter. These ion channels open in response to glutamate binding, resulting in depolarization of the postsynaptic membrane and influx of calcium. Receptor localization plays a key role in synaptic strength, and changes in receptor number and location underpin synaptic plasticity, learning and memory. Here we apply receptor subunit-specific antibody fragments and multiplexed gold nanoparticle conjugates, together with cryo-electron tomography (cryo-ET), to elucidate the in-situ molecular organization of AMPA and NMDA receptors at hippocampal synapses in adult mouse brain tissue. AMPA receptors are predominantly found in densely packed liquid-like clusters, with interspersed NMDA receptors and adjacent NMDA receptor clusters. By direct localization of individual receptors, we provide molecular-resolution insight into the distribution of AMPA and NMDA receptors across the synapse, at peri and extrasynaptic sites, and within endocytosed vesicles. Visualization of multiple presynaptic vesicle fusion events suggests that receptors are near, but not always directly adjacent to, transmitter release sites. By mapping AMPA and NMDA receptors, and glutamate release sites, we provide receptor-resolution insight into the structure and function of brain hippocampal synapses.

neuroscience↗

bioRxiv2026

Programmable gold nanoparticle conjugates enable precise AMPA receptor localization at brain synapses by cryo-ET

Cryo-electron tomography (cryo-ET) is a powerful approach to image cells, organelles, viruses and molecular assemblies. However, resolving smaller complexes and molecules is challenging and presents a roadblock to the broad application of cryo-ET. Gold nanoparticles (AuNPs) have been used to localize otherwise unidentifiable molecules and complexes in tomograms but are typically tethered to the target of interest via a flexible linker. As a result, the position of the AuNP does not directly define the location of the target. Here we attach AuNPs to Fab antibody fragments via cysteine residues on defined elements of secondary structure and show that the AuNPs are rigidly bound to the Fab. We use these Fab-AuNP conjugates to locate AMPA receptors and probe their conformation upon desensitization with sub nanometer resolution in tomograms derived from brain slice lamella. By harnessing small, homogeneous AuNPs with precise conjugation to a Fab, we have developed reagents that enable direct investigation of conformational states of previously unidentifiable biomolecules and complexes in tomograms.

biochemistry↗

bioRxiv2026

AMPAR immunization induces progressive autoimmune encephalitis with autoreactive B cells in the brain

AMPA and NMDA receptors are central to synaptic plasticity and cognitive function. In anti-NMDA receptor and anti-AMPA receptor (AMPAR) encephalitis, autoantibodies targeting these receptors disrupt synaptic signaling, leading to severe neuropsychiatric symptoms. However, the cellular autoimmune responses and source of pathogenic autoantibodies during onset and progression of central nervous system (CNS) pathology remain poorly understood. By immunizing mice with intact AMPARs in proteoliposomes, we developed a mouse model of anti-AMPAR encephalitis. Mice developed rapidly progressing neuropsychiatric deficits, autoantibodies targeting the AMPAR amino-terminal domain (ATD) and IgG deposition in the brain, accompanied by reduced AMPAR detection. Throughout disease onset and progression, AMPAR-ATD-specific non-proliferating plasma cells and plasmablasts accumulated in the brain and were predominantly localized in AMPAR-expressing brain parenchyma. In contrast, differentiated AMPAR-ATD specific B cells were far less enriched in peripheral lymphoid tissues. Our results suggest that humoral autoimmune responses directly in the CNS drives disease progression in anti-AMPAR encephalitis.

neuroscience↗