title: A helminth cestode parasite express an estrogen-binding protein resembling a classic nuclear estrogen receptor.
abstract: The role of an estrogen-binding protein similar to a known mammalian estrogen receptor (ER) is described in the estradiol-dependent reproduction of the helminth parasite Taenia crassiceps. Previous results have shown that 17-β-estradiol induces a concentration-dependent increase in bud number of in vitro cultured cysticerci. This effect is inhibited when parasites are also incubated in the presence of an ER binding-inhibitor (tamoxifen). RT-PCR assays using specific oligonucleotides of the most conserved ER sequences, showed expression by the parasite of a mRNA band of molecular weight and sequence corresponding to an ER. Western blot assays revealed reactivity with a 66 kDa protein corresponding to the parasite ER protein. Tamoxifen treatment strongly reduced the production of the T. crassiceps ER-like protein. Antibody specificity was demonstrated by immunoprecipitating the total parasite protein extract with anti-ER-antibodies. Cross-contamination by host cells was discarded by flow cytometry analysis. ER was specifically detected on cells expressing paramyosin, a specific helminth cell marker. Parasite cells expressing the ER-like protein were located by confocal microscopy in the subtegumental tissue exclusively. Analysis of the ER-like protein by bidimensional electrophoresis and immunoblot identified a specific protein of molecular weight and isoelectric point similar to a vertebrates ER. Sequencing of the spot produced a small fragment of protein similar to the mammalian nuclear ER. Together these results show that T. crassiceps expresses an ER-like protein which activates the budding of T. crassiceps cysticerci in vitro. To the best of our knowledge, this is the first report of an ER-like protein in parasites. This finding may have strong implications in the fields of host-parasite co-evolution as well as in sex-associated susceptibility to this infection, and could be an important target for the design of new drugs.
authors.affiliation: Departamento de Inmunología, Instituto de Investigaciones Biomédicas, Universidad Nacional Autónoma de México, AP 70228, México DF 04510, México.
authors.forename: Elizabeth Guadalupe
authors.initials: EG
authors.lastname: Ibarra-Coronado
authors.forename: Galileo
authors.initials: G
authors.lastname: Escobedo
authors.forename: Karen
authors.initials: K
authors.lastname: Nava-Castro
authors.forename: Chávez-Rios
authors.initials: CR
authors.lastname: Jesús Ramses
authors.forename: Romel
authors.initials: R
authors.lastname: Hernández-Bello
authors.forename: Martìn
authors.initials: M
authors.lastname: García-Varela
authors.forename: Javier R
authors.initials: JR
authors.lastname: Ambrosio
authors.forename: Olivia
authors.initials: O
authors.lastname: Reynoso-Ducoing
authors.forename: Rocío
authors.initials: R
authors.lastname: Fonseca-Liñán
authors.forename: Guadalupe
authors.initials: G
authors.lastname: Ortega-Pierres
authors.forename: Lenin
authors.initials: L
authors.lastname: Pavón
authors.forename: María Eugenia
authors.initials: ME
authors.lastname: Hernández
authors.forename: Jorge
authors.initials: J
authors.lastname: Morales-Montor
mesh_terms: D000818:Animals; D015153:Blotting, Western; D002589:Cestoda / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D004958:Estradiol / Q000494:pharmacology; D004967:Estrogens / Q000378:metabolism*; D015801:Helminth Proteins / Q000235:genetics / Q000378:metabolism*; D007525:Isoelectric Focusing; D011485:Protein Binding; D011960:Receptors, Estrogen / Q000235:genetics / Q000378:metabolism*; D012098:Reproduction / Q000187:drug effects; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D004967:Estrogens; D015801:Helminth Proteins; D011960:Receptors, Estrogen; D013629:Tamoxifen; D004958:Estradiol