Morphodynamics of the Actin-Rich Cytoskeleton in Entamoeba histolytica

Abstract

Entamoeba histolytica is the anaerobic protozoan parasite responsible for human amoebiasis, the third most deadly parasitic disease worldwide. This highly motile eukaryotic cell invades human tissues and constitutes an excellent experimental model of cell motility and cell shape deformation. The absence of extranuclear microtubules in Entamoeba histolytica means that the actin-rich cytoskeleton takes on a crucial role in not only amoebic motility but also other processes sustaining pathogenesis, such as the phagocytosis of human cells and the parasite's resistance of host immune responses. Actin is highly conserved among eukaryotes, although diverse isoforms exist in almost all organisms studied to date. However, E. histolytica has a single actin protein, the structure of which differs significantly from those of its human homologs. Here, we studied the expression, structure and dynamics of actin in E. histolytica. We used molecular and cellular approaches to evaluate actin gene expression during intestinal invasion by E. histolytica trophozoites. Based on a three-dimensional structural bioinformatics analysis, we characterized protein domains differences between amoebic actin and human actin. Fine-tuned molecular dynamics simulations enabled us to examine protein motion and refine the three-dimensional structures of both actins, including elements potentially accounting for differences changes in the affinity properties of amoebic actin and deoxyribonuclease I. The dynamic, multifunctional nature of the amoebic cytoskeleton prompted us to examine the pleiotropic forms of actin structures within live E. histolytica cells; we observed the cortical cytoskeleton, stress fibers, “dot-like” structures, adhesion plates, and macropinosomes. In line with these data, a proteomics study of actin-binding proteins highlighted the Arp2/3 protein complex as a crucial element for the development of macropinosomes and adhesion plaques.

Acetylation is the most abundant actin modification inEntamoeba histolyticaand modifications of actin's amino‐terminal domain change cytoskeleton activities

“…However, this is not the case because real differences exist between the Mt1 and Mt2 phenotypes, albeit both cell types overexpress a mutant allele. Furthermore, the controls with cells transfected with the wild‐type gene in this work (CTL transfectant) in addition to data from our previous work (Manich et al, ) indicates that overexpression of the wild type actin gene does not induce the phenotypes found in Mt1 and Mt2 cells. However, the Mt1 and Mt2 cells contained a mixture of wild type and mutant actins in their cytoplasm, which probably explains the intermediate phenotypes.…”

“…Confocal images were acquired with a Zeiss LSM 700 laser scanning microscope (focal plane size: 0.5 μm). Actin‐rich structures such as dot‐like contact points, endocytic cups, and large adhesion plates were counted according to previous published methods (Manich et al, ).…”

“…The preparations were mounted on slides using PROLONG antifading reagent containing 4′,6diamidino-2-phenylindole (DAPI) (Molecular Probes, United States).Confocal images were acquired with a Zeiss LSM 700 laser scanning microscope (focal plane size: 0.5 μm). Actin-rich structures such as dotlike contact points, endocytic cups, and large adhesion plates were counted according to previous published methods(Manich et al, 2018). 6.10 | Growth kinetics, quantification of the number of nuclei, and determination of cell size…”

The interaction betweenEntamoeba histolyticaand enterobacteria shed light on an ancient antibacterial response

“…Further works in the Cell Biology of Parasitism unit and in collaborative groups put all of these findings into perspective. More insights on amoebic motility and the signalling pathways supporting displacements during infection have been published recently (Aguilar‐Rojas et al, ; Boquet‐Pujadas et al, ; Dufour, Olivo‐Marin, & Guillen, ; Manich et al, ; Hernandez‐Cuevas, Jhingan, Petropolis, Vargas, & Guillen, ). In agreement with the subject of this review, I will focus on the relationship between Enterobacteriaceae and E. histolytica .…”

“…supporting displacements during infection have been published recently (Aguilar-Rojas et al, 2005; Boquet-Pujadas et al, 2017;Dufour, Olivo-Marin,Manich et al, 2018; …”