Biology subjects

Lanoue, V.

Publications and source records attributed to Lanoue, V..

3 recordsLinked to original sources

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↗

bioRxiv2022

Synaptotagmin 1 mediates toxicity of botulinum neurotoxin type A

The extreme neurotoxicity of botulinum neurotoxins (BoNTs), broadly used as a therapeutics, is mediated by their direct binding to two plasma membrane receptors: polysialogangliosides (PSGs) and serotype-dependently either synaptotagmin 1/2 (Syt1/2) or synaptic vesicle glycoprotein 2 (SV2). Here, we demonstrate that although BoNT/A serotype binds directly to PSG and SV2, its neurotoxicity depends on Syt1. Using single-molecule superresolution microscopy of pathological concentrations of BoNT/A holotoxins, we demonstrate that the toxin binds to a preassembled PSG-Syt1 complex that forms nanoclusters with SV2 on the plasma membrane of hippocampal neurons. This coincidental interaction controls the selective endocytic targeting of BoNT/A into synaptic vesicles, leading to incapacitation of neuronal communication. Our results suggest that Syt1-SV2 plasma membrane nanoclusters may acts as a common target for various BoNT serotypes. One-Sentence SummaryBoNT/A hijacks an intrinsic tripartite PSG-Syt1-SV2 endocytic sorting mechanism to incapacitate neuronal communication

neuroscience↗

bioRxiv2018

Actomyosin-II facilitates long-range retrograde transport of large cargoes by controlling axonal radial contractility

Most mammalian neurons have a narrow axon, which constrains the passage of large cargoes such as autophagosomes that can be larger than the axon diameter. Radial axonal expansion must therefore occur to ensure efficient axonal trafficking. In this study we consistently find that the trafficking speed of various large axonal cargoes is significantly slower than that of small ones, and reveal that the transit of diverse-sized cargoes causes an acute, albeit transient axonal radial expansion, which is immediately restored by constitutive contractility. Using live super-resolution microscopy, we demonstrate that actomyosin-II controls axonal radial contractility and local expansion, and that NM-II filaments associate with periodic F-actin rings via their head domains. Pharmacological inhibition of NM-II activity, significantly increases axon diameter by detaching the NM-II from F-actin, and impacts the trafficking speed, directionality, and overall efficiency of long-range retrograde trafficking. Consequently, prolonged disruption of NM-II activity leads to disruption of periodic actin rings and formation of focal axonal swellings, a hallmark of axonal degeneration.\n\nSummaryAxonal radial contractility and local expansion control the retrograde trafficking of large cargoes. The periodic actomyosin-II network comprises of NM-II filaments and F-actin rings. Loss of actomyosin-II-mediated radial contractility causes defects in axonal trafficking and stability, leading to degeneration.

neuroscience↗