Biology subjects

Rivas-Serna, I. M.

Publications and source records attributed to Rivas-Serna, I. M..

3 recordsLinked to original sources

bioRxiv2026

The functional neuronal lipotype is specified by activity and PS synthesis using dietary and lysosomal inputs

Neurons maintain specialized membranes necessary for lifelong circuit function. While neuronal membranes thus contain unique lipidomes, how and why specific lipids become synaptically enriched remains mysterious. Here, we identify a conserved hallmark of mature neurons, phosphatidylserines containing omega-3 fatty acids (n-3 PS), which dynamically accumulate during synaptogenesis from Drosophila to humans. This neuronal lipotype depends on dietary n-3 and lysosomal catabolism mediated by Saposin, the phospholipase PLA2G15, and the lysophospholipid transporter spin/SPNS1. Reducing neuronal PS biosynthesis by targeting the PS synthase (Pss) caused lipidomic, synaptic, and behavioral deficits exacerbated by impaired glycerophospholipid catabolism. While dietary, lysosomal, and lipoprotein manipulations broadly altered n-3 levels, silencing developmental activity-templating neurons selectively reduced n-3 PS. Remarkably, pathogenic Pss variants lacking feedback inhibition similarly reduced n-3 PS and impaired circuit function. As n-3 PS is reduced during neurodegeneration but absent from iPSC-derived neurons, important relationships between lipotype and physiology may not be recapitulated in vitro.

neuroscience↗

bioRxiv2025

Glia phagocytose neuronal sphingolipids to infiltrate developing synapses

The complex morphologies of mature neurons and glia emerge through profound rearrangements of cell membranes during development. Despite being integral components of these membranes, it is unclear whether lipids might actively sculpt these morphogenic processes. By analyzing lipid levels in the developing fruit fly brain, we discover dramatic increases in specific sphingolipids coinciding with neural circuit establishment. Disrupting this sphingolipid bolus via genetic perturbations of sphingolipid biosynthesis and catabolism leads to impaired glial autophagy. Remarkably, glia can obtain sphingolipid precursors needed for autophagy by phagocytosing neurons. These precursors are then converted into specific long-chain ceramide phosphoethanolamines (CPEs), invertebrate analogs of sphingomyelin. These lipids are essential for glia to arborize and infiltrate the brain, a critical step in circuit maturation that when disrupted leads to reduced synapse numbers. Taken together, our results demonstrate how spatiotemporal tuning of sphingolipid metabolism during development plays an instructive role in programming brain architecture. HighlightsO_LIBrain sphingolipids (SLs) remodel to very long-chain species during circuit maturation C_LIO_LIGlial autophagy requires de novo SL biosynthesis coordinated across neurons and glia C_LIO_LIGlia evade a biosynthetic blockade by phagolysosomal salvage of neuronal SLs C_LIO_LICeramide Phosphoethanolamine is critical for glial infiltration and synapse density C_LI

neuroscience↗

bioRxiv2022

Glial control of sphingolipid levels sculpts diurnal remodeling of sleep circuitry

Structural plasticity in the brain often necessitates dramatic remodeling of neuronal processes and attendant reorganization of the cytoskeleton and membranes. While cytoskeletal restructuring has been studied extensively, how lipids might orchestrate structural plasticity remains unclear. We show that specific glial cells in Drosophila produce Glucocerebrosidase (GBA) to locally catabolize sphingolipids. Sphingolipid accumulation drives lysosomal dysfunction, causing gba1b mutants to harbor protein aggregates that cycle across circadian time and are regulated by neural activity, the circadian clock, and sleep. While the vast majority of membrane lipids are stable across the day, a specific subset, highly enriched in sphingolipids, cycles daily in a gba1b-dependant fashion. In parallel, circadian clock neurons remodel their neurites, growing and shrinking across the day to shape circadian behavior. Remarkably, this neuronal remodeling relies on a cycle of temporally offset sphingolipid biosynthesis and catabolism. Thus, dynamic sphingolipid regulation by glia enables diurnal circuit remodeling and proper circadian behavior.

neuroscience↗