Biology subjects

Garlick, E.

Publications and source records attributed to Garlick, E..

6 recordsLinked to original sources

bioRxiv2026

βII and βIII spectrin paralogues define robustness and specialization of the neuronal membrane periodic skeleton

Neuron connectivity and signal processing rely on a complex, dynamic morphology regulated by the cytoskeleton. The membrane-associated periodic skeleton (MPS), a 190-nm periodic actin-spectrin lattice, is a conserved feature of neurons. Here, we show that the dendritic MPS is built from a dual {beta}-spectrin system in which {beta}II- and {beta}III-spectrins are co-expressed and interleaved at the nanoscale in shafts and spine necks. 3D MINFLUX nanoscopy suggests that these paralogues form both homotypic ({beta}II- or {beta}III-only) and heterotypic ({beta}II/{beta}III) tetramers with an approximately 100-nm radial periodicity. Either paralogue alone is sufficient to maintain lattice architecture, whereas their combined loss disrupts MPS integrity. Using targeted mutagenesis, we show that actin binding is required to stabilize both paralogues within the MPS, whereas {beta}III-spectrin additionally depends on phosphoinositide interactions. Our findings reveal that, unlike the axonal MPS, the dendritic MPS is a composite scaffold in which structural redundancy coexists with paralogue-specific regulatory mechanisms, with potential consequences for synaptic function.

neuroscience↗

bioRxiv2025

3D MINFLUX combined with DNA-PAINT resolves the arrangement of Bassoon at active zones

Neurotransmitter release and membrane retrieval at active zones require precise spatial and temporal coordination relying on an intricate molecular machinery. However, the exact nano-structural organization of this machinery is not yet fully elucidated. Here, we used 3D MINFLUX combined with both spectral demixing and DNA-PAINT to analyze the positioning of the scaffolding protein Bassoon at presynaptic active zones of glutamatergic spine synapses of hippocampal neurons, achieving a localization precision of 5 nm in 3D. This approach allowed us to visualize directly the distribution of N-terminal and the C-terminal regions of Bassoon, and demonstrates that Bassoon exhibits an orientation at the active zone, where the C-terminal region is directed toward the synaptic cleft and the N-terminal region towards synaptic vesicles. Having demonstrated this spatial configuration for endogenous and recombinant Bassoon molecules, our study paves the way towards molecular-scale resolution analysis of other prominent proteins of the presynaptic release machinery.

neuroscience↗

bioRxiv2025

Charting the nanotopography of inner hair cell synapses using MINFLUX nanoscopy

For us to hear, the cochlea encodes sounds into neural signals at synapses of inner hair cells (IHCs) and the auditory nerve with remarkable fidelity. To achieve the high rates of temporally precise synaptic transmission over long periods of time, IHCs employ sophisticated ribbon-type active zones (AZ). In order for us to understand synaptic sound encoding, we need to decipher the underpinning molecular topography of these synapse which had remained challenging due to technological limitations. Here we applied 3-dimensional minimal flux optical nanoscopy to mouse IHC synapses to chart the position of key pre- and postsynaptic proteins with single digit nanometre resolution of imaging. We demonstrate that nanoclusters of channels and interacting proteins govern the topography of AZs and postsynaptic densities (PSDs). We count synaptic proteins, their nanoclusters and determine their spatial organization feeding into computational modelling of AZ function. In conclusion, this study reveals a nanocluster-based molecular AZ and PSD topography, likely serving as functional modules in synaptic sound encoding.

neuroscience↗

bioRxiv2024

Expansion microscopy allows quantitative characterisation of structural organisation of platelet aggregates

1Current microscopy approaches applied to platelet aggregates in both haemostatic and thrombotic settings indicate their structure has important implications in efficient haemostasis and in clinical treatment of thrombosis. However, current fluorescence microscopy approaches are not amenable to volumetric imaging of platelet aggregate structures. This is largely due to the small size of individual platelets and the tight packing of platelets within aggregates, resulting in optical opacity. Here we demonstrate that expansion microscopy, applied to platelet aggregates, can reveal multi-scale information about the structure of platelet aggregates. We produced volumetric images at nanoscale resolution of >700 platelet aggregates under normal and perturbed conditions, stained for cytoskeletal and membrane components. We demonstrate our custom analysis workflow provides quantitative description of platelet numbers, volumes and morphology within entire platelet aggregates. Additionally, we quantitatively describe subcellular organisation of F-actin. By comparing these measurements following treatment with the actin inhibitors, cytochalasin D and latrunculin A, we can robustly detect structural disruptions in platelet aggregates. Together these data provide a workflow to qualitatively and quantitatively describe the architecture of platelet aggregates at a range of scales (whole aggregates down to sub-cellular features within individual platelets).

cell biology↗

bioRxiv2021

Simple methods for quantifying super-resolved cortical actin

Cortical actin plays a key role in cell movement and division, but has also been implicated in the organisation of cell surface receptors such as G protein-coupled receptors. The actin mesh proximal to the inner membrane forms small fenced regions, or corrals, in which receptors can be constrained. Quantification of the actin mesh at the nanoscale has largely been attempted in single molecule datasets and electron micrographs. This work describes the development and validation of workflows for analysis of super resolved fixed cortical actin images obtained by both Super Resolved Radial Fluctuations (SRRF) and expansion microscopy (ExM). SRRF analysis was used to show a significant increase in corral area when treating cells with the actin disrupting agent cytochalasin D (increase of 0.31{micro}m2 {+/-} 0.04 SEM), and ExM analysis allowed for the quantitation of actin filament densities. Thus this work allows complex actin networks to be quantified from super-resolved images and is amenable to both fixed and live cell imaging.

cell biology↗

bioRxiv2020

CLEC-2 promotes inflammatory peritoneal macrophage emigration to draining lymph nodes during endotoxemia

Macrophage recruitment during sterile inflammation and infection is essential to clear pathogens, apoptotic cells and debris. However, persistent macrophage accumulation leads to chronic inflammation. Platelets are emerging as key modulators of the inflammatory response. Here, we identify that platelet C-type-lectin-like receptor-2 (CLEC-2) is a crucial immunomodulatory receptor through the interaction with podoplanin, upregulated on inflammatory macrophages. Mechanistically, platelet CLEC-2 upregulates the expression of podoplanin and its co-ligands CD44 and ERM proteins, leading to actin rearrangement and promotion of cell migration; this is mimicked by recombinant CLEC-2-Fc (rCLEC-2-Fc). Treatment of LPS-challenged mice with rCLEC-2-Fc induces a rapid emigration of peritoneal macrophages to mesenteric lymph nodes, through a gradient generated by the podoplanin ligand, CCL21, to prime T cells. We propose that crosslinking podoplanin using rCLEC-2-Fc is a novel, cell-specific strategy to accelerate macrophage removal from the site of inflammation, and hence promote the resolution of the inflammatory response. Visual Abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=188 SRC="FIGDIR/small/423770v1_ufig1.gif" ALT="Figure 1"> View larger version (54K): org.highwire.dtl.DTLVardef@e37acborg.highwire.dtl.DTLVardef@92a5e1org.highwire.dtl.DTLVardef@1c8832eorg.highwire.dtl.DTLVardef@11c5c97_HPS_FORMAT_FIGEXP M_FIG C_FIG SummaryPersistent macrophage accumulation in inflamed tissue leads to chronic inflammation and organ damage. Bourne et al. identify recombinant CLEC-2-Fc crosslinking podoplanin on inflammatory macrophages, as a cell-specific strategy to accelerate their emigration to draining lymph nodes, and reduce local inflammation.

immunology↗