Escherichia coliDraE Adhesin-Associated Bacterial Internalization by Epithelial Cells Is Promoted Independently by Decay-Accelerating Factor and Carcinoembryonic Antigen-Related Cell Adhesion Molecule Binding and Does Not Require the DraD Invasin

Abstract

The Dr family of Escherichia coli adhesins are virulence factors associated with diarrhea and urinary tract infections. Dr fimbriae are comprised of two subunits. DraE/AfaE represents the major structural, antigenic, and adhesive subunit, which recognizes decay-accelerating factor (DAF) and carcinoembryonic antigen (CEA)-related cell adhesion molecules (CEACAMs) CEA, CEACAM1, CEACAM3, and CEACAM6 as binding receptors. The DraD/AfaD subunit caps fimbriae and has been implicated in the entry of Dr-fimbriated E. coli into host cells. In this study, we demonstrate that DAF or CEACAM receptors independently promote DraEmediated internalization of E. coli by CHO cell transfectants expressing these receptors. We also found that DraE-positive recombinant bacteria adhere to and are internalized by primary human bladder epithelial cells which express DAF and CEACAMs. DraE-mediated bacterial internalization by bladder cells was inhibited by agents which disrupt lipid rafts, microtubules, and phosphatidylinositol 3-kinase (PI3K) activity. Immunofluorescence confocal microscopic examination of epithelial cells detected considerable recruitment of caveolin, ␤ 1 integrin, phosphorylated ezrin, phosphorylated PI3K, and tubulin, but not F-actin, by cell-associated bacteria. Finally, we demonstrate that the DraD subunit, previously implicated as an "invasin," is not required for ␤ 1 integrin recruitment or bacterial internalization.Urinary tract infections (UTIs) represent the most common kidney and urologic disease, affecting more than 60% of women during their lifetime (17,18). A common feature of UTI is its recurrence. About 25% of women with a first UTI have a second episode within 6 months (16). Escherichia coli is the most common etiologic agent, causing more than 80% of all UTIs. One E. coli virulence factor associated with UTI is

Virulence Factors of Uropathogenic E. coli and Their Interaction with the Host

“…In addition, β1 integrins confer bacterial internalisation involving the microtubules system and caveolae (Guignot et al, 2001;Korotkova et al, 2008). Within the host cell, Afa/Dr appears to promote intracellular multiplication in a similar manner as has been described for type 1 fimbriae (Goluszko, Popov, et al, 1997;Jouve et al, 1997).…”

Pathogenesis of Human Enterovirulent Bacteria: Lessons from Cultured, Fully Differentiated Human Colon Cancer Cell Lines

“…Lipid rafts play a role in the cell entry of Dr-and F1845-positive Afa/Dr DAF/CEACAMs DAEC into Caco-2/TC7 cells, since the ganglioside GM1 and VIP21/caveolin are recruited around adhering bacteria, and extraction of the membrane cholesterol with methyl-beta-cyclodextrin disorganizes the membrane lipid rafts and inhibits the cell entry of Afa/Dr DAF/CEACAMs DAEC (536,537). It is important to note that it has been established that the cell entry of Afa/Dr DAF/CEACAMs DAEC into epithelial cells is triggered by their major adhesin subunits E (538,539). The role of the D subunits of Afa/Dr DAF/CEACAMs DAEC, known as invasins (540,541), in the entry into epithelial cells remains controversial (542)(543)(544)(545)(546)(547).…”

Inhibition of CEA release from epithelial cells by lipid A of Gram-negative bacteria

“…We used ATCC E. coli strain 25922, which possesses Class II P-fimbriae [27]. Previous studies indicated that various strains of E. coli with type 1 fimbriae interact with CEA and other human CEACAM family members through the Afa/Dr family of adhesins [28][29][30]. We have not examined the binding of the E. coli ATCC 25922 strain to CEA.…”