Shiga toxin 2 causes apoptosis in human brain microvascular endothelial cells via C/EBP homologous protein.
Shiga toxin 1 (Stx1) and Stx2 produced by Escherichia coli O157 are known to be cytotoxic to Vero and HeLa cells by inhibiting protein synthesis and by inducing apoptosis. In the present study, we have demonstrated that 10 ng/ml Stx2 induced DNA fragmentation in human brain microvascular endothelial cells (HBMEC), with cleavage activation of caspase-3, -6, -8, and -9. A microarray approach used to search for apoptotic potential signals in response to Stx2 revealed that Stx2 treatment induced a marked upregulation of C/EBP homologous protein (CHOP)/growth arrest and DNA damage-inducible protein 153 (GADD153). Increased CHOP expression was dependent on enzymatically active Stx1. Knockdown of CHOP mRNA reduced the activation of caspase-3 and prevented apoptotic cell death. These results suggest that Stx2-induced apoptosis is mediated by CHOP in HBMEC and involves activation of both the intrinsic and extrinsic pathways of apoptosis.
Department of Bacteriology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, 812-8582, Japan. junfujii@bact.med.kyushu-u.ac.jp.
Jun
J
Fujii
Katie
K
Wood
Fumiko
F
Matsuda
Benedito A
BA
Carneiro-Filho
Keilo H
KH
Schlegel
Takashi
T
Yutsudo
Beth
B
Binnington-Boyd
Clifford A
CA
Lingwood
Fumiko
F
Obata
Kwang S
KS
Kim
Shin-ichi
S
Yoshida
Tom
T
Obrig
D017209:Apoptosis; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D002478:Cells, Cultured; D002843:Chromatin / Q000648:ultrastructure; D053938:DNA Fragmentation; D042783:Endothelial Cells / Q000187:drug effects* / Q000382:microbiology*; D020869:Gene Expression Profiling; D020868:Gene Silencing; D006801:Humans; D046529:Microscopy, Electron, Transmission; D020411:Oligonucleotide Array Sequence Analysis; D022641:Shiga Toxin 2 / Q000633:toxicity*; D050827:Syntaxin 1 / Q000235:genetics / Q000378:metabolism; D051742:Transcription Factor CHOP / Q000096:biosynthesis*
D002843:Chromatin; C497249:DDIT3 protein, human; C494212:STX1A protein, human; D022641:Shiga Toxin 2; D050827:Syntaxin 1; D051742:Transcription Factor CHOP; D020169:Caspases