title: Binding and Endocytosis of Bovine Hololactoferrin by the Parasite Entamoeba histolytica.
abstract: Entamoeba histolytica is a human parasite that requires iron (Fe) for its metabolic function and virulence. Bovine lactoferrin (B-Lf) and its peptides can be found in the digestive tract after dairy products are ingested. The aim of this study was to compare virulent trophozoites recently isolated from hamster liver abscesses with nonvirulent trophozoites maintained for more than 30 years in cultures in vitro regarding their interaction with iron-charged B-Lf (B-holo-Lf). We performed growth kinetics analyses of trophozoites in B-holo-Lf and throughout several consecutive transfers. The virulent parasites showed higher growth and tolerance to iron than nonvirulent parasites. Both amoeba variants specifically bound B-holo-Lf with a similar K d . However, averages of 9.45 × 10(5) and 6.65 × 10(6) binding sites/cell were found for B-holo-Lf in nonvirulent and virulent amoebae, respectively. Virulent amoebae bound more efficiently to human and bovine holo-Lf, human holo-transferrin, and human and bovine hemoglobin than nonvirulent amoebae. Virulent amoebae showed two types of B-holo-Lf binding proteins. Although both amoebae endocytosed this glycoprotein through clathrin-coated vesicles, the virulent amoebae also endocytosed B-holo-Lf through a cholesterol-dependent mechanism. Both amoeba variants secreted cysteine proteases cleaving B-holo-Lf. These data demonstrate that the B-Lf endocytosis is more efficient in virulent amoebae.
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida IPN 2508, 07360 México, DF, Mexico.
authors.forename: Guillermo
authors.initials: G
authors.lastname: Ortíz-Estrada
authors.affiliation: Departamento de Bioquímica, CINVESTAV-IPN, Avenida IPN 2508, 07360 México, DF, Mexico.
authors.forename: Víctor
authors.initials: V
authors.lastname: Calderón-Salinas
authors.affiliation: Departamento de Infectómica y Patogénesis Molecular, CINVESTAV-IPN, Avenida IPN 2508, 07360 México, DF, Mexico.
authors.forename: Mineko
authors.initials: M
authors.lastname: Shibayama-Salas
authors.affiliation: Unidad de Investigación, Facultad de Medicina, Universidad Autónoma de Sinaloa, Cedros y Sauces, Fraccionamiento los Fresnos, 80246 Culiacán, SIN, Mexico.
authors.forename: Nidia
authors.initials: N
authors.lastname: León-Sicairos
authors.affiliation: Departamento de Biología Celular, Centro de Investigación y de Estudios Avanzados del IPN (CINVESTAV-IPN), Avenida IPN 2508, 07360 México, DF, Mexico.
authors.forename: Mireya
authors.initials: M
authors.lastname: de la Garza
mesh_terms: D000818:Animals; D001665:Binding Sites; D002417:Cattle; D006224:Cricetinae; D004705:Endocytosis / Q000235:genetics; D004748:Entamoeba histolytica / Q000378:metabolism* / Q000472:pathogenicity; D006454:Hemoglobins / Q000378:metabolism; D006801:Humans; D007781:Lactoferrin / Q000378:metabolism*; D010271:Parasites / Q000378:metabolism / Q000472:pathogenicity*; D053058:Trophozoites / Q000378:metabolism* / Q000469:parasitology
chemical_list: D006454:Hemoglobins; C492629:hololactoferrin, human; D007781:Lactoferrin