Host Cell Vimentin Restrains Toxoplasma gondii Invasion and Phosphorylation of Vimentin is Partially Regulated by Interaction with TgROP18

He, Cheng; Kong, Ling; Zhou, Lijuan; Xia, Jing; Wei, Haixia; Liu, Min; Peng, Hongjuan

Host cell invasion by T. gondii is an active process that relies on regulated secretion of adhesive proteins and gliding motility powered by the Ivyspring International Publisher actin-myosin motor complex [10] . This process also relies on host cell cytoskeleton reorganization, which is regulated by T. gondii during infection [11] . Disruption of host cell actin cytoskeleton integrity decreases T. gondii cell invasion [12] . Vimentin, a type III intermediate filament cytoskeletal protein, is highly conserved in all vertebrates and is dynamically expressed and undergoes a complex phosphorylation pattern during development and differentiation [13, 14] . Vimentin has critical implications for pathophysiology; for example, it is not only an organizer of a number of critical proteins involved in cell adhesion, migration, and signaling [15, 16] , it also has key roles in bacterial [17] and viral [18, 19] infections, including pathogen entry and multiplication. A significant rearrangement of host cell vimentin around the Toxoplasma parasitophorous vacuoles (PVs) occurs throughout the course of infection, and this association between host cell vimentin and PVs can be observed within an hour after T. gondii invasion [20] . Moreover, the expression of vimentin in different cells or tissues is regulated by T. gondii infection. For example, vimentin expression is up-regulated in Müller cells in a mouse model of congenital ocular toxoplasmosis [21] , while it is down-regulated in Toxoplasma-infected macrophages [22] .