Biophysical Society Thematic Meeting | Bucharest 2026

Biophysics of Membrane Reactions in Brian

Tuesday Speaker Abstracts

ILLUMINATING NEUROSECRETION: OPTOGENETIC AND CLICK CHEMISTRY NOVEL TOOLS TO HIGHLIGHT THE MULTIPLE ROLES OF PHOSPHATIDIC ACID IN NEUROTRANSMITTER RELEASE Nicolas Vitale Institut for Cellular and Molecular Integrated Neurosciences, CNRS UPR3212, Strasbourg, France The orchestrated release of neurotransmitters or hormones by secretory cells involves many vesicular trafficking steps for efficient and rapid release. In addition to key proteins, the contribution of lipids in these various steps along the secretory pathway has been recently postulated. Among them, phosphatidic acid (PA), the simplest glycerophospholipid, has been proposed to play pivotal roles in key trafficking steps, especially in membrane fusion and fission events, where lipid remodeling is deemed crucial. For instance, using genetic knockdown, pharmacological inhibition of PA-producing enzymes, and PA sensors, we have highlighted the diverse contribution of this phospholipid across multiple stages of neurosecretion. Furthermore, lipidomic analysis of fractionated membranes has revealed the widespread presence of PA in numerous subcellular compartments and its active modulation during cellular stimulation. This sheds light on the complexity of PA signaling, with the existence of different PA pools defined not only in space, but also in time. However, establishing a functional link between these pools and the multiple functions attributed to PA has remained impossible using currently available tools. Hence, to overcome both spatial and temporal limitations, we developed a novel optogenetic strategy targeting lipid metabolism to specific organelles and new PA clickable PA analogues. Hence, using light sensible PA metabolism enzymes to induce recruitment at specific subcellular membranes, we achieved by the minute modulation of PA levels within specific compartments. This precise control of PA levels coupled with confocal imaging to monitor exocytic sites enabled us, for the first time, to establish insights into the distinct pools of PA involved in specific steps of the secretory pathway. Furthermore, to preserve the biological properties of PA synthetic analogues, we developed a novel strategy for the synthesis of azide based analogues allowing specific fatty acyl chain positioning. After functional validation of mono and poly-unsaturated forms of PA analogues in bovine chromaffin cells, we characterized their functional interactome during neurosecretion leading to the identification of known PA interactors involved in exocytosis and many additional potential novel interactors. Altogether, these results validate the versality of these tools to study the biological activities of PA and could be extended to other glycerophopsholipids.

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