scholarly journals Activation of Rho GTPases by Cytotoxic Necrotizing Factor 1 Induces Macropinocytosis and Scavenging Activity in Epithelial Cells

2001 ◽  
Vol 12 (7) ◽  
pp. 2061-2073 ◽  
Author(s):  
Carla Fiorentini ◽  
Loredana Falzano ◽  
Alessia Fabbri ◽  
Annarita Stringaro ◽  
Mariaantonia Logozzi ◽  
...  

Macropinocytosis, a ruffling-driven process that allows the capture of large material, is an essential aspect of normal cell function. It can be either constitutive, as in professional phagocytes where it ends with the digestion of captured material, or induced, as in epithelial cells stimulated by growth factors. In this case, the internalized material recycles back to the cell surface. We herein show that activation of Rho GTPases by a bacterial protein toxin, theEscherichia coli cytotoxic necrotizing factor 1 (CNF1), allowed epithelial cells to engulf and digest apoptotic cells in a manner similar to that of professional phagocytes. In particular, we have demonstrated that 1) the activation of all Rho, Rac, and Cdc42 by CNF1 was essential for the capture and internalization of apoptotic cells; and 2) such activation allowed the discharge of macropinosomal content into Rab7 and lysosomal associated membrane protein-1 acidic lysosomal vesicles where the ingested particles underwent degradation. Taken together, these findings indicate that CNF1-induced “switching on” of Rho GTPases may induce in epithelial cells a scavenging activity, comparable to that exerted by professional phagocytes. The activation of such activity in epithelial cells may be relevant, in mucosal tissues, in supporting or integrating the scavenging activity of resident macrophages.

2006 ◽  
Vol 74 (7) ◽  
pp. 3765-3772 ◽  
Author(s):  
Loredana Falzano ◽  
Perla Filippini ◽  
Sara Travaglione ◽  
Alessandro Giamboi Miraglia ◽  
Alessia Fabbri ◽  
...  

ABSTRACT Evidence is accumulating that a growing number of bacterial toxins act by modulating the eukaryotic cell cycle machinery. In this context, we provide evidence that a protein toxin named cytotoxic necrotizing factor 1 (CNF1) from uropathogenic Escherichia coli is able to block cell cycle G2/M transition in the uroepithelial cell line T24. CNF1 permanently activates the small GTP-binding proteins of the Rho family that, beside controlling the actin cytoskeleton organization, also play a pivotal role in a large number of other cellular processes, including cell cycle regulation. The results reported here show that CNF1 is able to induce the accumulation of cells in the G2/M phase by sequestering cyclin B1 in the cytoplasm and down-regulating its expression. The possible role played by the Rho GTPases in the toxin-induced cell cycle deregulation has been investigated and discussed. The activity of CNF1 on cell cycle progression can offer a novel view of E. coli pathogenicity.


2019 ◽  
Vol 22 (2) ◽  
Author(s):  
Alessia Fabbri ◽  
Sara Travaglione ◽  
Francesca Rosadi ◽  
Giulia Ballan ◽  
Zaira Maroccia ◽  
...  

2001 ◽  
Vol 291 (6-7) ◽  
pp. 551-554 ◽  
Author(s):  
Alessia Fabbri ◽  
Loredana Falzano ◽  
Sara Travaglione ◽  
Annarita Stringaro ◽  
Walter Malorni ◽  
...  

2007 ◽  
Vol 18 (7) ◽  
pp. 2735-2744 ◽  
Author(s):  
Alessandro Giamboi Miraglia ◽  
Sara Travaglione ◽  
Stefania Meschini ◽  
Loredana Falzano ◽  
Paola Matarrese ◽  
...  

Cytotoxic necrotizing factor 1 (CNF1) is a protein toxin produced by some pathogenic strains of Escherichia coli that specifically activates Rho, Rac, and Cdc42 GTPases. We previously reported that this toxin prevents the ultraviolet-B–induced apoptosis in epithelial cells, with a mechanism that remained to be defined. In this work, we show that the proteasomal degradation of the Rho GTPase is necessary to achieve cell death protection, because inhibition of Rho degradation abolishes the prosurvival activity of CNF1. We hypothesize that Rho inactivation allows the activity of Rac to become dominant. This in turn leads to stimulation of the phosphoinositide 3-kinase/Akt/IκB kinase/nuclear factor-κB prosurvival pathway and to a remarkable modification in the architecture of the mitochondrial network, mainly consisting in the appearance of elongated and interconnected mitochondria. Importantly, we found that Bcl-2 silencing reduces the ability of CNF1 to protect cells against apoptosis and that it also prevents the CNF1-induced mitochondrial changes. It is worth noting that the ability of a bacterial toxin to induce such a remodeling of the mitochondrial network is herein reported for the first time. The possible pathophysiological relevance of this finding is discussed.


2004 ◽  
Vol 279 (34) ◽  
pp. 35849-35857 ◽  
Author(s):  
Patrick Munro ◽  
Gilles Flatau ◽  
Anne Doye ◽  
Laurent Boyer ◽  
Olivier Oregioni ◽  
...  

2007 ◽  
Vol 204 (10) ◽  
pp. 2253-2257 ◽  
Author(s):  
Iliyan D. Iliev ◽  
Gianluca Matteoli ◽  
Maria Rescigno

Recent work suggests that dendritic cells (DCs) in mucosal tissues are “educated” by intestinal epithelial cells (IECs) to suppress inflammation and promote immunological tolerance. After attack by pathogenic microorganisms, however, “non-educated” DCs are recruited from nearby areas, such as the dome of Peyer's patches (PPs) and the blood, to initiate inflammation and the ensuing immune response to the invader. Differential epithelial cell (EC) responses to commensals and pathogens may control these two tolorogenic and immunogenic functions of DCs.


BMC Cancer ◽  
2014 ◽  
Vol 14 (1) ◽  
Author(s):  
Eleonora Vannini ◽  
Anna Panighini ◽  
Chiara Cerri ◽  
Alessia Fabbri ◽  
Simonetta Lisi ◽  
...  

1998 ◽  
Vol 5 (11) ◽  
pp. 921-929 ◽  
Author(s):  
Carla Fiorentini ◽  
Paola Matarrese ◽  
Elisabetta Straface ◽  
Loredana Falzano ◽  
Gianfranco Donelli ◽  
...  

2003 ◽  
Vol 71 (3) ◽  
pp. 1161-1169 ◽  
Author(s):  
Patrick Brest ◽  
Baharia Mograbi ◽  
Véronique Hofman ◽  
Agnès Loubat ◽  
Bernard Rossi ◽  
...  

ABSTRACT Some strains of Escherichia coli related to acute cystitis or colitis produce a toxin named cytotoxic necrotizing factor 1 (CNF-1). CNF-1 mediates its effects on epithelial cells or phagocytes via the permanent activation of small GTP-binding proteins, caused by the toxin-induced deamidation of Glu63 of p21 Rho. The behavior of peripheral blood T lymphocytes during the acute phase of bacterial colitis has been poorly investigated. Our study was conducted to test whether (i) peripheral blood T lymphocytes can be activated by CNF-1 and (ii) CNF-1-activated T lymphocytes are cytotoxic against intestinal epithelial cells. Activation of T lymphocytes by CNF-1 was assessed by electrophoresis, flow cytometry, confocal microscopy, and electron microscopy studies. Assays for migration and adherence of CNF-1-treated T lymphocytes were performed in Transwell chambers with T84 intestinal epithelial cells grown on polycarbonate semipermeable filters. CNF-1 induced a decrease in the electrophoretic mobility of the GTP-binding protein Rho in treated T lymphocytes. CNF-1 provoked an increase in the content of actin stress fibers and pseudopodia in T lymphocytes. Several adherence molecules were clustered into cytoplasmic projections in CNF-1-treated T lymphocytes and adherence of such lymphocytes on the basolateral pole of T84 was increased, resulting in cytotoxicity toward epithelial cells. Such enhanced adherence in response to CNF-1 was dependent on p42-44MAP kinase activation of T lymphocytes. Taken together, these results suggest that CNF-1, by acting on T lymphocytes, may increase in an important fashion the virulence of certain strains of E. coli against the intestinal epithelia.


2012 ◽  
Vol 81 (1) ◽  
pp. 99-109 ◽  
Author(s):  
Tamako A. Garcia ◽  
Christy L. Ventura ◽  
Mark A. Smith ◽  
D. Scott Merrell ◽  
Alison D. O'Brien

Cytotoxic necrotizing factor 1 (CNF1) and hemolysin (HlyA1) are toxins produced by uropathogenicEscherichia coli(UPEC). We previously showed that these toxins contribute to the inflammation and tissue damage seen in a mouse model of ascending urinary tract infection. CNF1 constitutively activates small Rho GTPases by deamidation of a conserved glutamine residue, and HlyA1 forms pores in eukaryotic cell membranes. In this study, we used cDNA microarrays of bladder tissue isolated from mice infected intraurethrally with wild-type CP9, CP9cnf1, or CP9ΔhlyAto further evaluate the role that each toxin plays in the host response to UPEC. Regardless of the strain used, we found that UPEC itself elicited a significant change in host gene expression 24 h after inoculation. The largest numbers of upregulated genes were in the cytokine and chemokine signaling and Toll-like receptor signaling pathways. CNF1 exerted a strong positive influence on expression of genes involved in innate immunity and signal transduction and a negative impact on metabolism- and transport-associated genes. HlyA1 evoked an increase in expression of genes that encode innate immunity factors and a decrease in expression of genes involved in cytoskeletal and metabolic processes. Multiplex cytokine and myeloperoxidase assays corroborated our finding that a strong proinflammatory response was elicited by all strains tested. Bladders challenged intraurethrally with purified CNF1 displayed pathology similar to but significantly less intense than the pathology that we observed in CP9-challenged mice. Our data demonstrate substantial roles for CNF1 and HlyA1 in initiation of a strong proinflammatory response to UPEC in the bladder.


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