Botulinum Neurotoxins A and E Undergo Retrograde Axonal Transport in Primary Motor Neurons

PLoS Pathogens

Francesco Giribaldi¹  Giampietro Schiavo²  Guillermo Menendez³  Laura Restani⁴  Kinga Bercsenyi⁴  Matteo Caleo⁴  Maria Manich⁴  Ornella Rossetto⁴ 

[1] CNR, Neuroscience Institute, Pisa, Italy;Department ofBiomedical Sciences, University of Padova, Padova, Italy;Institut Pasteur, Unité des Bactéries anaérobies et Toxines, Paris, France;Molecular NeuroPathobiology Laboratory, Cancer Research UK London Research Institute, London, United Kingdom

关键词: Motor neurons;    Axonal transport;    Cellular structures;    organelles;    Neurotoxins;    Spinal cord;    Toxins;    Synaptic vesicles;    Botulinum toxin;   

DOI  :  10.1371/journal.ppat.1003087

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

The striking differences between the clinical symptoms of tetanus and botulism have been ascribed to the different fate of the parental neurotoxins once internalised in motor neurons. Tetanus toxin (TeNT) is known to undergo transcytosis into inhibitory interneurons and block the release of inhibitory neurotransmitters in the spinal cord, causing a spastic paralysis. In contrast, botulinum neurotoxins (BoNTs) block acetylcholine release at the neuromuscular junction, therefore inducing a flaccid paralysis. Whilst overt experimental evidence supports the sorting of TeNT to the axonal retrograde transport pathway, recent findings challenge the established view that BoNT trafficking is restricted to the neuromuscular junction by highlighting central effects caused by these neurotoxins. These results suggest a more complex scenario whereby BoNTs also engage long-range trafficking mechanisms. However, the intracellular pathways underlying this process remain unclear. We sought to fill this gap by using primary motor neurons either in mass culture or differentiated in microfluidic devices to directly monitor the endocytosis and axonal transport of full length BoNT/A and BoNT/E and their recombinant binding fragments. We show that BoNT/A and BoNT/E are internalised by spinal cord motor neurons and undergo fast axonal retrograde transport. BoNT/A and BoNT/E are internalised in non-acidic axonal carriers that partially overlap with those containing TeNT, following a process that is largely independent of stimulated synaptic vesicle endo-exocytosis. Following intramuscular injection in vivo, BoNT/A and TeNT displayed central effects with a similar time course. Central actions paralleled the peripheral spastic paralysis for TeNT, but lagged behind the onset of flaccid paralysis for BoNT/A. These results suggest that the fast axonal retrograde transport compartment is composed of multifunctional trafficking organelles orchestrating the simultaneous transfer of diverse cargoes from nerve terminals to the soma, and represents a general gateway for the delivery of virulence factors and pathogens to the central nervous system.

【 授权许可】

CC BY