Epithelial cells challenged with a Rac-activating E. coli cytotoxin acquire features of professional phagocytes.
Activation of Rho, Rac and Cdc42 GTPases by an Escherichia coli cytotoxin (CNF1) has been reported to induce a phagocytic-like activity by epithelial cells in terms of a ruffle-driven capture and ingestion of large material. More recently, it has been reported that treatment with CNF1 induces superoxide anion release by these cells following a phagocytic stimulus. We herein show that in epithelial cells both transfection with the dominant form of Rac (RacV12) and treatment with the Rac-activating epidermal growth factor (EGF) may increase the secretion of superoxide anions on challenge with latex beads. Moreover, exposure to CNF1 induces a significant augmentation of acidic vesicles where the internalized particles were detectable. Our results indicate that (i) Rac is a pivotal GTPase for inducing in epithelial cells superoxide anion generation and (ii) the internalized material travels trough acidic compartments in CNF1-treated epithelial cells. Altogether this suggests a novel role for epithelial cells that, following Rac activation, might share with professional phagocytes the task of eliminating unwanted pathogens.
Department of Ultrastructures, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
L
L
Falzano
R
R
Rivabene
A
A
Fabbri
C
C
Fiorentini
D001427:Bacterial Toxins / Q000494:pharmacology*; D003603:Cytotoxins / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects / Q000502:physiology*; D004926:Escherichia coli; D029968:Escherichia coli Proteins; D006801:Humans; D010586:Phagocytes / Q000502:physiology*; D012234:Rho Factor / Q000494:pharmacology*; D014162:Transfection; D020764:cdc42 GTP-Binding Protein / Q000494:pharmacology; D020744:rac GTP-Binding Proteins / Q000096:biosynthesis / Q000494:pharmacology*
D001427:Bacterial Toxins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; D012234:Rho Factor; C060296:cytotoxic necrotizing factor type 1; D020764:cdc42 GTP-Binding Protein; D020744:rac GTP-Binding Proteins