Biology subjects

Dumaire, N. L.

Publications and source records attributed to Dumaire, N. L..

3 recordsLinked to original sources

bioRxiv2025

RhoA activation promotes ordered membrane domain coalescence and suppresses neuronal excitability

The formation of ordered proteolipid membrane domains (OMDs) within the plasma membrane has emerged as a fundamental process that modifies membrane function, particularly in response to cell stresses that promote pathological states. Here, we identify a previously unrecognized role for the small GTPase RhoA to promote the coalescence of OMDs, thereby linking cytoskeletal remodeling and membrane mechanics to OMD formation. Pharmacological and optogenetic manipulation of RhoA rapidly altered OMD dimensions in both human cell lines and dorsal root ganglion (DRG) nociceptors. The RhoA-dependent OMD expansion required actin remodeling, changes in membrane mechanical state, and protein palmitoylation. Functionally, RhoA inhibition increased action potential firing and potentiated HCN channel activity in DRG neurons. Conversely, in a spared nerve injury model characterized by altered membrane mechanics, reduced OMD size, and hyperexcitability, RhoA activation enlarged OMDs, suppressed HCN channel activity, and reduced firing. These findings highlight alterations in plasma membrane physical properties, including changes in OMD organization and membrane tension, as key features of neuropathic stress. RhoA/ROCK-driven OMD remodeling may serve as a compensatory membrane adaptation that counteracts neuropathic hyperexcitability.

biophysics↗

bioRxiv2025

Cholesterol Inhibits HCN Channels through Dual Mechanisms in Neuropathic Pain

Cholesterol, abundantly present in distinct plasma membrane pools, is a critical modulator of ion channel function, including hyperpolarization-activated cyclic nucleotide-gated (HCN) channels that regulate the excitability of dorsal root ganglion (DRG) nociceptor neurons. Depletion of membrane cholesterol potentiated HCN channel opening and accelerated activation kinetics, whereas cholesterol supplementation reduced channel opening and slowed activation kinetics. However, the relative contributions of cholesterol that organizes ordered membrane domains (OMDs) versus freely accessible cholesterol pools to HCN channel modulation remain unknown. Using fluorescence lifetime imaging microscopy and Forster resonance energy transfer (FRET), and fluorescence anisotropy techniques, we examined how supplementing cholesterol alters plasma membrane properties and HCN gating in nociceptor DRG neurons. We uncovered a process of sequential, stepwise membrane remodeling: an initial phase with OMD expansion and a rapid rise in free cholesterol, followed by continued accumulation of free cholesterol without further OMD expansion. Notably, the slope factor of the HCN conductance- voltage relationship is sensitive to OMD expansion but remains unaffected by changes in free cholesterol. Other gating parameters, including open probability and activation kinetics, were affected by elevating free cholesterol. In a rat model of nerve injury, where DRG neurons exhibit reduced free cholesterol levels and smaller OMDs, HCN channel modulation by cholesterol involves contributions from both OMD expansion and free cholesterol accumulation. In contrast, in naive DRG neurons--characterized by high cholesterol and large OMDs--modulation occurs mostly via increased free cholesterol. These findings deepen our understanding of cholesterols role in modulating ion channels and contributing to neuropathic pain.

neuroscience↗

bioRxiv2025

Direct Binding of FGFR3 Autoantibodies to Sensory Neurons Drives Hyperexcitability and Mechanical Hypersensitivity

Sensory neuronopathies (SNN) and small fiber neuropathies (SFN) are debilitating disorders associated with neuropathic pain, yet their underlying mechanisms remain poorly understood. Autoantibodies against fibroblast growth factor receptor 3 (FGFR3-Abs) define a subset of patients with consistent reports of neuropathic pain harboring a distinct clinical phenotype characterized by small-fiber and non-length-dependent neuropathy, suggesting dorsal root ganglia (DRG) dysfunction. FGFR3-Abs bind to sensory neurons within dorsal root ganglia (DRG). The target of autoantibodies FGFR3 is expressed at the transcript and protein level in human sensory neurons, suggesting that FGFR3-Abs could find their target in primary afferents. DRG neurons exposed to FGFR3-Abs rapidly acquired a hyperexcitability phenotype which was linked to mechanical hypersensitivity, mirroring patient-reported pain symptoms. CRISPR mediated gene editing of FGFR3 in sensory neuron prevented FGFR3-Abs induced sensitization of sensory neurons and mechanical hypersensitivity. In parallel, Epitope mapping reveals extracellular FGFR3 epitopes essential for antibody-induced sensitization and pain hypersensitivity. Together this work suggests that beyond their role as biomarkers, FGFR3-Abs are pathogenic in small fiber neuropathy by acting directly on DRG neurons. This positions both FGFR3-Abs and FGFR3 signaling as actionable therapeutic targets for modulating sensory neuron excitability and treating autoimmune painful neuropathies.

neuroscience↗