The association of Shiga-like toxin with detergent-resistant membranes is modulated by glucosylceramide and is an essential requirement in the endoplasmic reticulum for a cytotoxic effect.
Receptor-mediated internalization to the endoplasmic reticulum (ER) and subsequent retro-translocation to the cytosol are essential sequential processes required for the productive intoxication of susceptible mammalian cells by Shiga-like toxin-1 (SLTx). Recently, it has been proposed that the observed association of certain ER-directed toxins and viruses with detergent-resistant membranes (DRM) may provide a general mechanism for their retrograde transport to endoplasmic reticulum (ER). Here, we show that DRM recruitment of SLTx bound to its globotriosylceramide (Gb(3)) receptor is mediated by the availability of other glycosphingolipids. Reduction in glucosylceramide (GlcCer) levels led to complete protection against SLTx and a reduced cell surface association of bound toxin with DRM. This reduction still allowed efficient binding and transport of the toxin to the ER. However, toxin sequestration within DRM of the ER was abolished under reduced GlcCer conditions, suggesting that an association of toxin with lipid microdomains or rafts in the ER (where these are defined by detergent insolubility) is essential for a later step leading to or involving retro-translocation of SLTx across the ER membrane. In support of this, we show that a number of ER residents, proteins intimately involved in the process of ER dislocation of misfolded proteins, are present in DRM.
Smith
Daniel C
DC
Department of Biological Sciences, University of Warwick, Coventry CV4 7AL, UK.
Sillence
Daniel J
DJ
Falguières
Thomas
T
Jarvis
Rosemary M
RM
Johannes
Ludger
L
Lord
J Michael
JM
Platt
Frances M
FM
Roberts
Lynne M
LM
D017485:1-Deoxynojirimycin / Q000031:analogs & derivatives; D000818:Animals; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D002522:Chlorocebus aethiops; D003902:Detergents / Q000494:pharmacology*; D004721:Endoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism*; D005963:Glucosylceramides / Q000378:metabolism*; D006028:Glycosphingolipids / Q000037:antagonists & inhibitors / Q000096:biosynthesis; D006367:HeLa Cells; D006801:Humans; D007425:Intracellular Membranes / Q000378:metabolism; D061988:Proteasome Inhibitors; D021381:Protein Transport / Q000187:drug effects; D022622:Shiga Toxin 1 / Q000378:metabolism* / Q000633:toxicity*; D014281:Trihexosylceramides / Q000494:pharmacology; D014709:Vero Cells
D003902:Detergents; D005963:Glucosylceramides; D006028:Glycosphingolipids; D061988:Proteasome Inhibitors; D022622:Shiga Toxin 1; D014281:Trihexosylceramides; D017485:1-Deoxynojirimycin; C018549:globotriaosylceramide; C090092:migalastat