Infect. Immun., Apr 1997, 1299-1306, Vol 65, No. 4
Copyright © 1997, American Society for Microbiology

Glucose up-regulates expression of the differentiation-associated brush border binding site for enterotoxigenic Escherichia coli colonization factor antigen I in cultured human enterocyte-like cells

MF Bernet-Camard, F Duigou, S Kerneis, MH Coconnier and AL Servin
CJF 94.07 INSERM, UFR de Pharmacie Paris XI, Chatenay-Malabry, France.

The association of enterotoxigenic Escherichia coli expressing colonization factor antigen I (CFA/I) with the cultured human colon adenocarcinoma cell, a model of the mature enterocyte of the small intestine, is dependent on the binding of CFA/I to a brush border- associated component. Binding of the purified radiolabeled [125I]CFA/I- and 14C-labeled CFA/I-positive bacteria could be displaced by an increasing concentration of unlabeled CFA/I. Moreover, we showed that expression of the specific CFA/I binding developed as a function of cell differentiation in Caco-2 cells, whereas expression of the nonspecific binding did not. Expression of the brush border differentiation-associated component acting as a binding site for CFA/I was up-regulated by glucose. Indeed, the enterocyte-like HT-29 glc- cell subpopulation not expressing the CFA/I binding site when cultured in dialyzed serum and hexose-free medium regained the ability to bind CFA/I when the cells were returned to culture medium containing glucose. Furthermore, expression of the brush border-associated CFA/I binding site in the enterocyte-like Caco-2 cells was repressed when the cells were cultured in hexose-free conditions.