title: Entamoeba histolytica cysteine proteinase 5 binds integrin on colonic cells and stimulates NFkappaB-mediated pro-inflammatory responses.
abstract: Integrins are important mammalian receptors involved in normal cellular functions and the pathogenesis of inflammation and disease. Entamoeba histolytica is a protozoan parasite that colonizes the gut, and in 10% of infected individuals, causes amebic colitis and liver abscess resulting in 10(5) deaths/year. E. histolytica-induced host inflammatory responses are critical in the pathogenesis of the disease, yet the host and parasite factors involved in disease are poorly defined. Here we show that pro-mature cysteine proteinase 5 (PCP5), a major virulent factor that is abundantly secreted and/or present on the surface of ameba, binds via its RGD motif to α(V)β(3) integrin on Caco-2 colonic cells and stimulates NFκB-mediated pro-inflammatory responses. PCP5 RGD binding to α(V)β(3) integrin triggered integrin-linked kinase(ILK)-mediated phosphorylation of Akt-473 that bound and induced the ubiquitination of NF-κB essential modulator (NEMO). As NEMO is required for activation of the IKKα-IKKβ complex and NFκB signaling, these events markedly up-regulated pro-inflammatory mediator expressions in vitro in Caco-2 cells and in vivo in colonic loop studies in wild-type and Muc2(-/-) mice lacking an intact protective mucus barrier. These results have revealed that EhPCP5 RGD motif is a ligand for α(V)β(3) integrin-mediated adhesion on colonic cells and represents a novel mechanism that E. histolytica trophozoites use to trigger an inflammatory response in the pathogenesis of intestinal amebiasis.
authors.affiliation: Department of Microbiology and Infectious Diseases, University of Calgary Health Sciences Centre, Calgary, Alberta T2N 4N1, Canada.
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Hou
authors.forename: Leanne
authors.initials: L
authors.lastname: Mortimer
authors.forename: Kris
authors.initials: K
authors.lastname: Chadee
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D015153:Blotting, Western; D018938:Caco-2 Cells; D057056:Cysteine Proteases / Q000235:genetics / Q000378:metabolism*; D016207:Cytokines / Q000378:metabolism; D004404:Dysentery, Amebic / Q000378:metabolism / Q000469:parasitology; D004748:Entamoeba histolytica / Q000201:enzymology / Q000502:physiology; D054884:Host-Pathogen Interactions; D006801:Humans; D051550:I-kappa B Kinase / Q000378:metabolism; D047468:Immunoprecipitation; D007249:Inflammation / Q000378:metabolism* / Q000469:parasitology; D039302:Integrin alphaVbeta3 / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D055262:Mucin-2 / Q000235:genetics / Q000378:metabolism; D016328:NF-kappa B / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011485:Protein Binding; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D016207:Cytokines; D039302:Integrin alphaVbeta3; C524626:Muc2 protein, mouse; D055262:Mucin-2; D016328:NF-kappa B; D015800:Protozoan Proteins; D051057:Proto-Oncogene Proteins c-akt; D051550:I-kappa B Kinase; D057056:Cysteine Proteases