title: Rho signaling in Entamoeba histolytica modulates actomyosin-dependent activities stimulated during invasive behavior.
abstract: Interaction of Entamoeba histolytica trophozoites with target cells and substrates activates signaling pathways in the parasite. Phosphorylation cascades triggered by phospho-inositide and adenyl-cyclase-dependent pathways modulate reorganization of the actin cytoskeleton to form structures that facilitate adhesion. In contrast, little is known about participation of Rho proteins and Rho signaling in actin rearrangements. We report here the in vivo expression of at least one Rho protein in trophozoites, whose activation induced actin reorganization and actin-myosin interaction. Antibodies to EhRhoA1 recombinant protein mainly localized Rho in the cytosol of nonactivated amoebae, but it was translocated to vesicular membranes and to some extent to the plasma membrane after treatment with lysophosphatidic acid (LPA), a specific agonist of Rho activation. Activated Rho was identified in LPA-treated trophozoites. LPA induced striking polymerization of actin into distinct dynamic structures. Disorganization of these structures by inhibition of Rho effector, Rho-kinase (ROCK), and by ML-7, an inhibitor of myosin light chain kinase dependent phosphorylation of myosin light chain, suggested that the actin structures also contained myosin. LPA stimulated concanavalin-A-mediated formation of caps, chemotaxis, invasion of extracellular matrix substrates, and erythrophagocytosis, but not binding to fibronectin. ROCK inhibition impaired LPA-stimulated functions and to some extent adhesion to fibronectin. Similar results were obtained with ML-7. These data suggest the presence and operation of Rho-signaling pathways in E. histolytica, that together with other, already described, signaling routes modulate actomyosin-dependent motile processes, particularly stimulated during invasive behavior.
authors.affiliation: Departamento de Biomedicina Molecular, CINVESTAV-IPN, México, DF, México.
authors.forename: Janusz
authors.initials: J
authors.lastname: Franco-Barraza
authors.forename: Horacio
authors.initials: H
authors.lastname: Zamudio-Meza
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Franco
authors.forename: M
authors.initials: M
authors.lastname: del Carmen Domínguez-Robles
authors.forename: Nicolás
authors.initials: N
authors.lastname: Villegas-Sepúlveda
authors.forename: Isaura
authors.initials: I
authors.lastname: Meza
mesh_terms: D000205:Actomyosin / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D002633:Chemotaxis / Q000502:physiology; D004748:Entamoeba histolytica / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D004749:Entamoebiasis / Q000378:metabolism; D004912:Erythrocytes / Q000469:parasitology; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010587:Phagocytosis / Q000502:physiology*; D016415:Sequence Alignment; D015398:Signal Transduction / Q000502:physiology*; D020741:rho GTP-Binding Proteins / Q000235:genetics / Q000502:physiology*; D020742:rhoA GTP-Binding Protein / Q000235:genetics
chemical_list: D016326:Extracellular Matrix Proteins; D000205:Actomyosin; D020741:rho GTP-Binding Proteins; D020742:rhoA GTP-Binding Protein