Biology subjects

Bademosi, A. T.

Publications and source records attributed to Bademosi, A. T..

5 recordsLinked to original sources

bioRxiv2026

Single-molecule bouncing at a liquid interface governs presynaptic enrichment

Many cellular processes rely on accumulating highly diffusive cytoplasmic proteins to a specific location within the cell. This spatial enrichment is generally thought to rely on locally immobilizing proteins or slowing diffusion through binding and molecular crowding. Paradoxically, cytoplasmic proteins that are enriched within nerve terminals remain highly diffusive, raising questions about the mechanisms that govern presynaptic enrichment. Here, using in vivo single-molecule microscopy, we tracked the diffusion of a model cytoplasmic protein, -Synuclein (-Syn), and synaptic vesicles (SVs), in motor neuron presynapses of live Drosophila larvae. We demonstrate that -Syn undergoes rapid and frequent "bouncing" events at a presynaptic interface, locally impeding escape from the presynapse. We measured escape probabilities at the interface, and show that impeding escape, without dramatically slowing diffusion, is sufficient to govern presynaptic enrichment. The interface is liquid-like and coincides with the boundary of the SV cluster, which is a necessary scaffold for the presynaptic enrichment of -Syn. Our results provide direct evidence of interfacial reflectivity at the interface of liquid-like compartments, and that this phenomenon can govern the subcellular enrichment of proteins and small organelles at the level of individual particles.

neuroscience↗

bioRxiv2025

Transmitted alpha-synuclein extracellular vesicles downregulate axonal flux of retrograde carriers in recipient neurons

-Synuclein (-syn) is a cytosolic protein located in nerve terminals and is involved in several neurodegenerative diseases such as Parkinsons disease. Recent studies have demonstrated that -syn can be transmitted from neuron to neuron via exosomal release, thereby contributing to the propagation of -syn pathology. However, the mechanism by which -syn-containing exosomes perturb the function of recipient neurons is currently unknown. Retrograde axonal transport of carriers emanating from the presynapse is essential for neuronal survival. To determine the effect of transmitted -syn on neuronal retrograde trafficking, we used conditioned medium from -syn transfected "donor" hippocampal neurons, applied to naive (non-transfected) "recipient" neurons cultured in microfluidic chambers. Time-lapse imaging of retrograde carriers containing cholera toxin-B subunit (CTB) was then performed in these recipient neurons. Here, we show that conditioned medium from -synWT-GFP transfected donor neurons significantly downregulated the frequency of retrograde CTB carriers when applied to recipient neurons. This effect was abolished by (i) inhibiting endocytosis in recipient neurons, (ii) by blocking exosomal release from donor cells via an Hsp90-dependent mechanism, or (iii) by using conditioned medium from neurons transfected with a Parkinsons mutant (-synA30P-GFP). Whilst transmitted -syn-mEos2, -synA30P-mEos2 and mEos2 alone were detected in recipient neurons using single molecule imaging, interestingly, -synWT-mEos2 exhibited lower mobility, and periodic (190 nm) immobilisations along the axon. Our data suggest that the downregulation of vesicular trafficking by transmitted -syn does not rely on the specific release nor uptake of exosomal -syn but probably depends on its interaction with endogenous -syn following endocytosis in recipient neurons. The transmitted -syn containing extracellular vesicles therefore controls essential axonal trafficking in recipient neurons, an effect lost with the Parkinsons disease mutant -synA30P.

neuroscience↗

bioRxiv2023

Defective Schwann cell lipid metabolism alters plasma membrane dynamics in Charcot-Marie-Tooth disease 1A

Duplication of PMP22 causes Charcot-Marie-Tooth disease type 1A (CMT1A) and is known to disrupt the lipid metabolism in myelinating Schwann cells by unknown mechanisms. By using two CMT1A mouse models overexpressing human PMP22, we discovered that PMP22 dose-dependently downregulates genes that are involved in lipid and cholesterol metabolism. Lipidomic analysis on CMT1A mouse sciatic nerves confirmed lipid metabolic abnormalities primarily associated with cholesterol and sphingolipids. We observed similar lipidomic profiles and downregulation of genes associated with lipid metabolism in human CMT1A patient induced pluripotent stem cell-derived Schwann cell precursors (iPSC-SCPs). We confirmed these findings by demonstrating altered lipid raft dynamics and plasma membrane fluidity in CMT1A iPSC-SCPs. Additionally, we identified impaired cholesterol incorporation in the plasma membrane due to altered lipid storage homeostasis in CMT1A iPSC-SCPs, which could be modulated by changing the lipid composition of the cell culture medium. These findings suggest that PMP22 plays a role in regulating the lipid composition of the plasma membrane and lipid storage homeostasis. Targeting lipid metabolism may hold promise as a potential treatment for CMT1A patients. Graphical abstract O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=162 SRC="FIGDIR/small/535224v1_ufig1.gif" ALT="Figure 1"> View larger version (50K): org.highwire.dtl.DTLVardef@17d4e84org.highwire.dtl.DTLVardef@1adce4forg.highwire.dtl.DTLVardef@1c3e1eborg.highwire.dtl.DTLVardef@12525da_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIPMP22 copy number causes a dose-dependent suppression of cholesterol and lipid biosynthesis in peripheral nerves of CMT1A mice C_LIO_LILipid composition is altered in the sciatic nerves of CMT1A mice and in the membranes of patient derived iPSC-SCPs, with a significant reduction in sphingolipids C_LIO_LICMT1A iPSC-SCPs show decreased plasma membrane lipids required for regulating lipid raft dynamics, membrane fluidity, and membrane order C_LIO_LILipid storage misregulation is key in the pathogenesis of CMT1A C_LI

neuroscience↗

bioRxiv2022

EndophilinA-dependent coupling between activity-dependent calcium influx and synaptic autophagy is disrupted by a Parkinson-risk mutation

Neuronal activity and neurotransmitter release cause use-dependent decline in protein function. However, it is unclear how this is coupled to local protein turnover and quality control mechanisms. Here we show that the endocytic protein Endophilin-A (EndoA/ENDOA1) couples activity-induced calcium influx to synaptic autophagy and neuronal survival. We identify single mutations in the EndoA flexible region that either increases EndoA diffusion and promotes autophagosome formation in the absence of calcium, or immobilizes EndoA and blocks autophagy, even in the presence of calcium. Hence, the EndoA flexible region is a switch that responds to calcium, regulating EndoA nanoscale synaptic organization and association with autophagosomes driving their formation. Interestingly, a pathogenic variant in the human ENDOA1 variable region that confers risk to Parkinsons disease (PD), also confines ENDOA1 to the synaptic plasma membrane and equally blocks autophagy in flies in vivo and in induced human neurons. Thus, our work reveals a mechanism neurons use to connect neuronal activity to local protein turnover by autophagy, which is critical for neuronal survival.

neuroscience↗

bioRxiv2020

Dissecting the nanoscale lipid profile of caveolae

Caveolae are specialized domains of the vertebrate cell surface with a well-defined morphology and crucial roles in cell migration and mechanoprotection. Unique compositions of proteins and lipids determine membrane architectures. The precise caveolar lipid profile and the roles of the major caveolar structural proteins, caveolins and cavins, in selectively sorting lipids have not been defined. Here we used quantitative nanoscale lipid mapping together with molecular dynamic simulations to define the caveolar lipid profile. We show that caveolin1 (CAV1) and cavin1 individually sort distinct plasma membrane lipids. Intact caveolar structures composed of both CAV1 and cavin1 further generate a unique lipid nano-environment. The caveolar lipid sorting capability includes selectivities for lipid headgroups and acyl chains. Because lipid headgroup metabolism and acyl chain remodelling are tightly regulated, this selective lipid sorting may allow caveolae to act as transit hubs to direct communications among lipid metabolism, vesicular trafficking and signalling.

biochemistry↗