Toxoplasma gondii Mechanisms of Entry Into Host Cells. 2020

Juliana Portes, and Emile Barrias, and Renata Travassos, and Márcia Attias, and Wanderley de Souza
Laboratório de Ultraestrutura Celular Hertha Meyer, Instituto de Biofísica Carlos Chagas Filho, Universidade Federal Do Rio de Janeiro, Rio de Janeiro, Brazil.

Toxoplasma gondii, the causative agent of toxoplasmosis, is an obligate intracellular protozoan parasite. Toxoplasma can invade and multiply inside any nucleated cell of a wide range of homeothermic hosts. The canonical process of internalization involves several steps: an initial recognition of the host cell surface and a sequential secretion of proteins from micronemes followed by rhoptries that assemble a macromolecular complex constituting a specialized and transient moving junction. The parasite is then internalized via an endocytic process with the establishment of a parasitophorous vacuole (PV), that does not fuse with lysosomes, where the parasites survive and multiply. This process of host cell invasion is usually referred to active penetration. Using different cell types and inhibitors of distinct endocytic pathways, we show that treatment of host cells with compounds that interfere with clathrin-mediated endocytosis (hypertonic sucrose medium, chlorpromazine hydrochloride, and pitstop 2 inhibited the internalization of tachyzoites). In addition, treatments that interfere with macropinocytosis, such as incubation with amiloride or IPA-3, increased parasite attachment to the host cell surface but significantly blocked parasite internalization. Immunofluorescence microscopy showed that markers of macropinocytosis, such as the Rab5 effector rabankyrin 5 and Pak1, are associated with parasite-containing cytoplasmic vacuoles. These results indicate that entrance of T. gondii into mammalian cells can take place both by the well-characterized interaction of parasite and host cell endocytic machinery and other processes, such as the clathrin-mediated endocytosis, and macropinocytosis.

UI MeSH Term Description Entries
D010873 Pinocytosis The engulfing of liquids by cells by a process of invagination and closure of the cell membrane to form fluid-filled vacuoles. Pinocytoses
D004705 Endocytosis Cellular uptake of extracellular materials within membrane-limited vacuoles or microvesicles. ENDOSOMES play a central role in endocytosis. Endocytoses
D006790 Host-Parasite Interactions The relationship between an invertebrate and another organism (the host), one of which lives at the expense of the other. Traditionally excluded from definition of parasites are pathogenic BACTERIA; FUNGI; VIRUSES; and PLANTS; though they may live parasitically. Host-Parasite Relations,Parasite-Host Relations,Host-Parasite Relationship,Parasite-Host Interactions,Host Parasite Interactions,Host Parasite Relations,Host Parasite Relationship,Host-Parasite Interaction,Host-Parasite Relation,Host-Parasite Relationships,Interaction, Host-Parasite,Interaction, Parasite-Host,Interactions, Host-Parasite,Interactions, Parasite-Host,Parasite Host Interactions,Parasite Host Relations,Parasite-Host Interaction,Parasite-Host Relation,Relation, Host-Parasite,Relation, Parasite-Host,Relations, Host-Parasite,Relations, Parasite-Host,Relationship, Host-Parasite,Relationships, Host-Parasite
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D014122 Toxoplasma A genus of protozoa parasitic to birds and mammals. T. gondii is one of the most common infectious pathogenic animal parasites of man. Toxoplasma gondii,Toxoplasma gondius,Toxoplasmas,gondius, Toxoplasma
D014123 Toxoplasmosis The acquired form of infection by Toxoplasma gondii in animals and man. Toxoplasma gondii Infection,Infection, Toxoplasma gondii
D014617 Vacuoles Any spaces or cavities within a cell. They may function in digestion, storage, secretion, or excretion. Vacuole

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