Differential entry of botulinum neurotoxin A into neuronal and intestinal cells.
Botulinum neurotoxins (BoNTs) are often acquired from the digestive tract and specifically target neuromuscular junctions where they cause an inhibition of acetylcholine release. A transcytotic mechanism has been evidenced in epithelial intestinal cells, which delivers whole BoNTs across the intestinal barrier, whereas BoNTs enter motoneurons through a pathway that permits the translocation of light chain into the cytosol. We used fluorescent BoNT/A C-terminal part of H chain (Hc) that mediates toxin binding to cell receptors to monitor toxin entry into NG108-15 neuronal cells as well as into Caco-2 and m-IC(cl2) intestinal cells. BoNT/A Hc receptors were found to be distributed in membrane structures closely associated to cholesterol-enriched microdomains, but distinct from detergent-resistant microdomains in both cell types. BoNT/A Hc was trapped into endocytic vesicles, which progressively migrated to a perinuclear area in NG108-15 cells, and in a more scattered manner in intestinal cells. In both cell types, BoNT/A Hc entered through a dynamin- and intersectin-dependent pathway, reached an early endosomal compartment labelled with early endosome antigen 1. In neuronal cells, BoNT/A Hc entered mainly via a clathrin-dependent pathway, in contrast to intestinal cells where it followed a Cdc42-dependent pathway, supporting a differential toxin routing in both cell types.
Couesnon
Aurélie
A
Unité des Bactéries anaérobies et Toxines, Institut Pasteur, 28 rue du Dr Roux, 75724 Paris cedex, France.
Shimizu
Takeshi
T
Popoff
Michel R
MR
D033942:Adaptor Proteins, Vesicular Transport / Q000378:metabolism; D019274:Botulinum Toxins, Type A / Q000378:metabolism*; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry; D002966:Clathrin / Q000378:metabolism; D003593:Cytoplasm / Q000737:chemistry; D034281:Dynamins / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D009474:Neurons / Q000378:metabolism*; D021381:Protein Transport; D022161:Transport Vesicles / Q000737:chemistry; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; D002966:Clathrin; C115919:intersectin 1; D019274:Botulinum Toxins, Type A; D020764:cdc42 GTP-Binding Protein; D034281:Dynamins