title: Cellular response induced by a galactose-specific adhesin of enteroaggregative Escherichia coli in INT-407 cells.
abstract: In the present study, the role of a fimbrial galactose-specific adhesin of the T7 strain of enteroaggregative Escherichia coli (EAEC-T7) in the signal transduction pathways in human small intestinal epithelial cells (INT-407) was explored. The adhesin was purified by anion exchange chromatography using a Mono Q HR5/5 column in the AKTA purifier system. The characteristic stacked brick pattern of aggregative adherence of EAEC-T7 to INT-407 cells was found to be inhibited in the presence of immunoglobulin G against the purified adhesin as well as d-galactose. The adhesin induced a significant increase in the intracellular calcium concentration [Ca(2+)](i) in INT-407 cells, which was reduced in the presence of dantrolene (inhibitor of intracellular calcium stores), verapamil, calciseptin (calcium channel blockers) as well as neomycin [inhibitor of phospholipase C (PLC)]. Further, an increased level of PLCgamma1 and inositol 1,4,5-tri phosphate as well as enhanced activity of protein kinase C (PKC) in the adhesin-stimulated cells were found to be downregulated in the presence of neomycin and U73122 (inhibitors of PLC) and H-7 (inhibitor of PKC), respectively. The adhesin could also induce interleukin-8 secretion from INT-407 cells, which was inhibited in the presence of dantrolene as well as staurosporin (inhibitor of PKC). Collectively, our results have suggested that the galactose-specific adhesin-induced signal transduction pathway might play a crucial role in the EAEC-induced pathogenesis.
authors.affiliation: Departments of Pediatrics, Post Graduate Institute of Medical Education & Research, Chandigarh, India.
authors.forename: Atul
authors.initials: A
authors.lastname: Goyal
authors.forename: Shalmoli
authors.initials: S
authors.lastname: Bhattacharyya
authors.forename: Siddhartha
authors.initials: S
authors.lastname: Majumdar
authors.forename: Anil
authors.initials: A
authors.lastname: Narang
authors.forename: Sujata
authors.initials: S
authors.lastname: Ghosh
mesh_terms: D018830:Adhesins, Escherichia coli / Q000378:metabolism*; D002118:Calcium / Q000032:analysis; D002460:Cell Line; D003600:Cytosol / Q000737:chemistry; D004847:Epithelial Cells / Q000378:metabolism* / Q000382:microbiology*; D004926:Escherichia coli / Q000502:physiology*; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate / Q000032:analysis; D016209:Interleukin-8 / Q000378:metabolism; D051966:Phospholipase C gamma / Q000032:analysis; D011493:Protein Kinase C / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D018830:Adhesins, Escherichia coli; D016209:Interleukin-8; D015544:Inositol 1,4,5-Trisphosphate; D011493:Protein Kinase C; C522157:PLCG1 protein, human; D051966:Phospholipase C gamma; D002118:Calcium