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.
Falzano
L
L
Department of Ultrastructures, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy.
Rivabene
R
R
Fabbri
A
A
Fiorentini
C
C
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