Uncommon membrane distribution of Shiga toxin glycosphingolipid receptors in toxin-sensitive human glomerular microvascular endothelial cells.
Membrane microdomain association of the glycosphingolipids (GSLs) globotriaosylceramide (Gb3Cer) and globotetraosylceramide (Gb4Cer), the highly and less effective receptors, respectively, for Shiga toxins (Stxs), is assumed as a functional requirement for Stx-mediated cytotoxicity. In a previous study, we demonstrated predominant localization of Stx receptors in cholesterol-enriched membrane microdomains of moderately Stx-sensitive human brain microvascular endothelial cells (HBMECs) by means of detergent-resistant membranes (DRMs). Here we report a different preferential distribution of Stx receptors in non-DRM fractions of human glomerular microvascular endothelial cells (GMVECs), the major targets of Stxs in the human kidney. Full structural characterization of Stx receptors using electrospray ionization (ESI) mass spectrometry revealed Gb3Cer and Gb4Cer lipoforms with ceramide moieties mainly composed of C24:0/C24:1 or C16:0 fatty acid and sphingosine (d18:1) in GMVECs comparable to those previously found in HBMECs. Thin-layer chromatography immunostaining demonstrated an approximately 2-fold higher content of Gb3Cer and a 1.4-fold higher content of Gb4Cer in GMVECs than in HBMECs. However, this does not explain the remarkable higher cytotoxic action of Stx1 and Stx2 toward GMVECs as compared with HBMECs. Our finding opens new questions on the microdomain association of Stx receptors and the functional role of GSLs in the membrane assembly of GMVECs.
Institute for Hygiene, University of Münster, D-48149 Münster, Germany.
Josefine
J
Betz
Andreas
A
Bauwens
Lisa
L
Kunsmann
Martina
M
Bielaszewska
Michael
M
Mormann
Hans-Ulrich
HU
Humpf
Helge
H
Karch
Alexander W
AW
Friedrich
Johannes
J
Müthing
D001921:Brain / Q000098:blood supply / Q000166:cytology; D002460:Cell Line; D002784:Cholesterol / Q000032:analysis / Q000378:metabolism; D002855:Chromatography, Thin Layer; D042783:Endothelial Cells / Q000166:cytology / Q000378:metabolism*; D005915:Globosides / Q000032:analysis* / Q000378:metabolism; D006028:Glycosphingolipids / Q000032:analysis* / Q000378:metabolism; D006801:Humans; D007678:Kidney Glomerulus / Q000098:blood supply / Q000166:cytology; D021962:Membrane Microdomains / Q000737:chemistry / Q000378:metabolism; D055806:Microvessels / Q000166:cytology; D022621:Shiga Toxin / Q000378:metabolism*; D021241:Spectrometry, Mass, Electrospray Ionization; D014281:Trihexosylceramides / Q000032:analysis* / Q000378:metabolism
D005915:Globosides; D006028:Glycosphingolipids; D014281:Trihexosylceramides; C024032:globotetraosylceramide; C018549:globotriaosylceramide; D022621:Shiga Toxin; D002784:Cholesterol