Article

Enterohemorrhagic Escherichia coli infection stimulates Shiga toxin 1 macropinocytosis and transcytosis across intestinal epithelial cells

Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
AJP Cell Physiology (Impact Factor: 3.78). 08/2011; 301(5):C1140-9. DOI: 10.1152/ajpcell.00036.2011
Source: PubMed

ABSTRACT

Gastrointestinal infection with Shiga toxins producing enterohemorrhagic Escherichia coli causes the spectrum of gastrointestinal and systemic complications, including hemorrhagic colitis and hemolytic uremic syndrome, which is fatal in ∼10% of patients. However, the molecular mechanisms of Stx endocytosis by enterocytes and the toxins cross the intestinal epithelium are largely uncharacterized. We have studied Shiga toxin 1 entry into enterohemorrhagic E. coli-infected intestinal epithelial cells and found that bacteria stimulate Shiga toxin 1 macropinocytosis through actin remodeling. This enterohemorrhagic E. coli-caused macropinocytosis occurs through a nonmuscle myosin II and cell division control 42 (Cdc42)-dependent mechanism. Macropinocytosis of Shiga toxin 1 is followed by its transcytosis to the basolateral environment, a step that is necessary for its systemic spread. Inhibition of Shiga toxin 1 macropinocytosis significantly decreases toxin uptake by intestinal epithelial cells and in this way provides an attractive, antibiotic-independent strategy for prevention of the harmful consequences of enterohemorrhagic E. coli infection.

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    • "On the other hand, if transepithelial or transendothelial CPP-mediated transport of a cargo drug is intended, the prominent criterion for efficient drug delivery relates to whether transcytosis follows the endocytic uptake. Transcytosis is exploited by various toxins subsequent to oral ingestion in order to transverse the epithelium for gaining access to the systemic circulation [87,88], but may also be the mechanism by which peptide and protein drugs are translocated across epithelia and endothelia when CPPs are employed as delivery vectors. As opposed to mediating endocytic cellular uptake, some CPPs are able to directly translocate across the plasma membrane in an energy-independent manner as demonstrated by the fact that CPP-uptake takes place when the temperature is lowered to 4 ˝ C [89]. "
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    • "Recent studies have demonstrated STEC-induced Stx uptake by macropinocytosis (Lukyanenko et al., 2011; In et al., 2013). To determine whether this pathway was also involved in Stx translocation in our experimental system, we investigated several indicators of macropinocytosis. "
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    • "The generation and accumulation of these vesicles have introduced a watery content into the cytoplasm, which contributed, at least partially, to the steep drop in the refractive index of EPEC-wt-infected cells (Figures 1D&2A). It is worth noting in this context that epithelial cell infection by the related pathogen enterohemorrhagic E. coli has also been reported to induce macropinocytosis [40], which is important for inserting a shiga-like toxin secreted by the microbe into its host. However, the role of EPEC-elicited basolateral (macro)pinocytosis remains to be elucidated. "
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