Molecular basis for up-regulation by inflammatory cytokines of Shiga toxin 1 cytotoxicity and globotriaosylceramide expression.
Mortality in postdiarrheal hemolytic-uremic syndrome (HUS) is associated with brain injury. Normally, brain cells are resistant to Shiga toxin (Stx), the putative pathogenic toxin in HUS. However, exposure of human brain endothelial cells (HBECs) to tumor necrosis factor (TNF) and/or interleukin (IL)-1 markedly up-regulates Stx receptor (globotriaosylceramide; Gb3) expression and cytotoxicity. To investigate how Gb3 is augmented, ceramide glucosyltransferase (CGT), lactosylceramide synthase (GalT2), Gb3 synthase (GalT6), and alpha-galactosidase were studied in HBECs exposed to TNF and IL-1. TNF, both alone and in combination with IL-1, increased Stx-1 toxicity, Gb3 content, and Stx-1 binding. TNF in combination with IL-1 increased CGT, GalT2, and GalT6 but did not change alpha-galactosidase activities or mRNA levels. Cytokine treatment did not change CGT, GalT2, or GalT6 mRNA half-lives. Thus, inflammatory cytokine up-regulation of the sensitivity of HBECs to Stx-1 is the result of up-regulation, most likely via transcription, of the activities of 3 enzymes involved in Gb3 synthesis.
Stricklett
Peter K
PK
Division of Nephrology, University of Utah School of Medicine, and Salt Lake Veterans Affairs Medical Center, Salt Lake City, Utah 84132, USA.
Hughes
Alisa K
AK
Ergonul
Zuhal
Z
Kohan
Donald E
DE
D001921:Brain / Q000098:blood supply; D002478:Cells, Cultured; D016207:Cytokines / Q000494:pharmacology* / Q000502:physiology; D004730:Endothelium, Vascular; D005700:Galactosyltransferases / Q000096:biosynthesis / Q000235:genetics; D005964:Glucosyltransferases / Q000096:biosynthesis / Q000235:genetics; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D012333:RNA, Messenger / Q000032:analysis; D022622:Shiga Toxin 1 / Q000378:metabolism / Q000633:toxicity*; D014281:Trihexosylceramides / Q000032:analysis / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D015854:Up-Regulation / Q000187:drug effects; D000519:alpha-Galactosidase / Q000235:genetics / Q000378:metabolism
D016207:Cytokines; D007375:Interleukin-1; D012333:RNA, Messenger; D022622:Shiga Toxin 1; D014281:Trihexosylceramides; D014409:Tumor Necrosis Factor-alpha; C018549:globotriaosylceramide; D005700:Galactosyltransferases; D005964:Glucosyltransferases; C045097:UDP-galactose-lactosylceramide alpha 1-4-galactosyltransferase; C039090:UDPgalactose-glucosylceramide galactosyltransferase; C023246:ceramide glucosyltransferase; D000519:alpha-Galactosidase