BPS2026 - Plasmalogen-dependent modulation of ordered membrane domains controls neuronal excitability

Plasma membranes are heterogeneous lipid bilayers, with each leaflet exhibiting distinct lipid compositions. Ordered membrane domains (OMDs), regions of plasma membranes enriched in sphingolipids and cholesterol, are known to regulate ion channel function, thereby influencing cellular excitability. Plasmalogens represent a unique subclass of phospholipids, distinguished by a vinyl-ether bond, and are enriched in ordered membrane compartments, affecting the physical properties of plasma membranes. It is also known that the plasmalogens, plasmenylcholine (pPC), and plasmenylethanolamine (pPE) are abundant in excitable tissues. The mechanism underlying how plasmalogens regulate membrane structure and how this, in turn, affects the function of membrane proteins remains unclear. Here, we investigated the role of plasmalogens in regulating OMDs of sensory neurons, and its impact on membrane structure and excitability. Following an overnight treatment of either 5 μM lyso-pPC or lyso-pPE to naive rat dorsal root ganglion (DRG) neurons, patch-clamp recordings showed that evoked action potential firing was reduced following lyso-pPC treatment, indicating decreased excitability. Fluorescence lifetime imaging microscopy (FLIM) combined with Förster resonance energy transfer (FRET) was used to monitor changes in OMD size following the same treatment with lyso-pPC via OMD-specific FRET pairs. Cholera toxin subunit B (CTxB)-based FRET probes showed an increase in efficiencies (Control: 14%; lyso-pPC: 19%) following the lyso-pPC treatment. In contrast, the FRET efficiency between probes based on small genetically encoded palmitoylated peptides was reduced (Control: 11%; lyso-pPC: 5%). These results indicate an overall increase in OMD size following lyso-pPC treatment in both rat DRG neurons and tsA-201 cells. Treatment with lyso-pPE showed no significant difference in patch-clamp or FLIM/FRET experiments. Together, these electrophysiological and FRET-based findings suggest that plasmalogens modulate excitability and membrane compartmentalization through OMD regulation, highlighting their potential as a therapeutic strategy for restoring plasma membrane structure and function.