Rho signaling in Entamoeba histolytica modulates actomyosin-dependent activities stimulated during invasive behavior

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 fac...

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Bibliographic Details
Published in:Cell motility and the cytoskeleton 2006-03, Vol.63 (3), p.117-131
Main Authors: Franco-Barraza, Janusz, Zamudio-Meza, Horacio, Franco, Elizabeth, Domínguez-Robles, M. del Carmen, Villegas-Sepúlveda, Nicolás, Meza, Isaura
Format: Article
Language:English
Subjects:
Actomyosin - physiology
Amino Acid Sequence
Animals
Cells, Cultured
Chemotaxis - physiology
cytoskeleton
Entamoeba histolytica
Entamoeba histolytica - genetics
Entamoeba histolytica - pathogenicity
Entamoeba histolytica - physiology
Entamoebiasis - metabolism
Erythrocytes - parasitology
Extracellular Matrix Proteins - metabolism
Humans
invasion
Molecular Sequence Data
motility
parasites
Phagocytosis - physiology
rho GTP-Binding Proteins - genetics
rho GTP-Binding Proteins - physiology
Rho proteins
rhoA GTP-Binding Protein - genetics
Sequence Alignment
Signal Transduction - physiology
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Summary: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. Cell Motil. Cytoskeleton 2006. © 2006 Wiley‐Liss, Inc.
ISSN:0886-1544
1097-0169
DOI:10.1002/cm.20105