Two Atypical Enteropathogenic Escherichia coli Strains Induce the Production of Secreted and Membrane-Bound Mucins To Benefit Their Own Growth at the Apical Surface of Human Mucin-Secreting Intestinal HT29-MTX Cells

Abstract

In rabbit ligated ileal loops, two atypical enteropathogenic Escherichia coli (aEPEC) strains, 3991-1 and 0421-1, intimately associated with the cell membrane, forming the characteristic EPEC attachment and effacement lesion of the brush border, induced a mucous hypersecretion, whereas typical EPEC (tEPEC) strain E2348/69 did not. Using cultured human mucin-secreting intestinal HT29-MTX cells, we demonstrate that apically aEPEC infection is followed by increased production of secreted MUC2 and MUC5AC mucins and membrane-bound MUC3 and MUC4 mucins. The transcription of the MUC5AC and MUC4 genes was transiently upregulated after aEPEC infection. We provide evidence that the apically adhering aEPEC cells exploit the mucins' increased production since they grew in the presence of membrane-bound mucins, whereas tEPEC did not. The data described herein report a putative new virulence phenomenon in aEPEC.The intestinal mucus offers numerous ecological advantages to bacteria present in the lumen and intestinal epithelium, providing a source of energy by producing the saccharides used for sustained growth by both the indigenous enteric microbiota and pathogens (26). Moreover by producing mucus, goblet cells contribute to the physical and chemical barriers that protect the host against the unwanted intrusion of enterovirulent microorganisms (48). Currently, 17 human mucin-type glycoproteins have been assigned to the MUC gene family, MUC1 and -2, MUC3A, MUC3B, MUC4, MUC5B, MUC5AC,, with the approval of the Human Genome Organization Gene Nomenclature Committee (HUGO/GNC; http://www.hugo-international.org/hugo/) (8, 9, 57). A cluster of four mucin genes (MUC2, MUC5B, MUC5AC, and MUC6) code for secreted mucins. Eight genes (MUC1, MUC3A, MUC3B, MUC4, MUC12, MUC13, MUC16, and MUC17) that code for membrane-associated mucins have been characterized. In mucin-secreting intestinal cells, the secreted mucins are packaged and stored into large intracellular vesicles (17, 39).Pathogenic Escherichia coli causes intestinal and extraintestinal diseases (35). There are six well-defined categories of intestinal pathogenic E. coli, each characterized by specific virulence factors that affect a wide range of cellular processes via signaling events. Enteropathogenic E. coli (EPEC), the first pathotype of E. coli to be described, produces characteristic cellular lesions known as "attaching and effacing" (A/E) lesions in the intestinal mucosa after the bacteria have intimately attached to the enterocyte brush border membrane and caused cytoskeletal changes that lead to effacement of the microvilli. The EPEC group is subdivided into typical (tEPEC) and atypical (aEPEC) forms. The aEPEC group consists of a large number of O serogroups (29, 74). These strains have been shown to carry the locus of the enterocyte effacement (LEE) pathogenicity island (PAI), but to lack the EAF (EPEC adherence factor) plasmid that encodes the bundle-forming pilus (BFP) and the Shiga toxin genes (35). LEE encodes the components of a type 3 secretion system (T3SS), an ...

Nature of bacterial colonization influences transcription of mucin genes in mice during the first week of life

“…While both gene products play protective roles during gut inflammatory conditions, at sites of epithelial damage [18,29-34] and during postnatal development [35,36], Muc2, unlike Tff3, polymerizes into a protective gel-like structure [1]. Based on the obtained results, it is however not possible to determine whether there is a connection between this difference in functionality and the corresponding gene regulation.…”

Isolation, Biochemical Characterization and Anti-adhesion Property of Mucin from the Blue Blubber Jellyfish (<i>Catostylus mosaicus</i>)

“…Our study has demonstrated that jellyfish mucins possess potential binding sites for P. aeruginosa and prevent its binding to epithelial cells grown in cell culture. There has been increasing interest directed toward the protective properties of mucins as a barrier against bacterial attachment to epithelial cells (Alemka et al, 2010;Bergstrom et al, 2010) and the mechanisms by which bacteria can utilise these mucin glycoproteins to facilitate adhesion and colonisation (Vieira et al, 2010;Linden et al, 2009). Our results show that GalNAc and Gal inhibit adhesion of Paer6294-GFP to cultured corneal epithelial cells and suggest that the interaction between bell mucin and P. aeruginosa is glycanmediated.…”

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

“…aEPEC adhering to fully differentiated, mucin-secreting HT29-MTX cells induces mucus hypersecretion, whereas tEPEC does not (783). The mucins produced are the secreted mucins MUC2 and MUC5AC and the membranebound mucins MUC3 and MUC4.…”