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[Mitogen activated protein kinases (MAPK) and Toxoplasma gondii host cell invasion]
F Robert-Gangneux1, C Creuzet, J Dupouy-Camet
1Laboratoire Signalisation et Parasites, UPRES EA 2499-INSERM U529, Faculté de Médecine Cochin-Port Royal, Université Paris V, 27, rue du Faubourg St Jacques, F75014 Paris.
Abstract:
Toxoplasmosis is still a big concern in Public Health in France, regarding two particular aspects: congenital toxoplasmosis and reactivated toxoplasmosis in immunodeficient patients. Toxoplasma gondii is an obligate intracellular parasite, that can invade almost all nucleated cells. The invasion step has been widely studied, but its accurate mechanism and the cell receptor remain largely unknown. In this work, we have attempted to investigate the role of kinases and signal transduction in the host cell penetration. We characterized mitogen-activated protein kinases (MAPK). in the parasite itself by immunoblotting, immunofluorescence, and determination of enzymatic activity. In particular, we identified two proteins of 43 and 47 kDa, that could be homologues of extracellular signal-regulated kinases (ERK), i.e. ERK2 and ERK1, respectively. These parasite MAPK are activated by calcium and phorbolmyristyl acetate and inhibited by RO 31-8220, suggesting an activation through protein kinases C (PKC). Indeed the MAPK kinase (= MEK) inhibitor PD98059 inhibits the activation of parasite MAPK, suggesting that a MEK homologue could be responsible for the dual phosphorylation of MAPK on tyrosine and threonine residues, necessary for their activation. Finally, we demonstrated that activation or inhibition of parasite MAPK by preincubation of parasites with various activators or inhibitors led to an increased or reduced host cell invasion in vitro by parasites, respectively. All these results are in favour of a role of ERK-type parasite kinases in T. gondii infectivity in vitro.
Insights
Toxoplasma gondii uses parasite-specific ERK-type kinases to invade host cells. Inhibiting these kinases reduces parasite infectivity, offering new targets for treating toxoplasmosis.
Area of Science:
- Parasitology
- Molecular Biology
- Cell Biology
Context:
- Toxoplasmosis poses significant public health challenges, particularly congenital and reactivated forms in immunocompromised individuals.
- Toxoplasma gondii, an obligate intracellular parasite, invades host cells via poorly understood mechanisms.
- Understanding parasite invasion is crucial for developing effective interventions.
Purpose:
- To investigate the role of host cell signaling pathways, specifically mitogen-activated protein kinases (MAPK), in Toxoplasma gondii invasion.
- To characterize parasite MAPK homologues and their activation mechanisms.
- To determine the impact of MAPK modulation on parasite infectivity.
Summary:
- Researchers identified and characterized parasite MAPK, likely ERK1 and ERK2, in Toxoplasma gondii.
- These parasite MAPKs are activated by calcium and phorbolmyristyl acetate, suggesting Protein Kinase C (PKC) involvement, and are dependent on a MEK homologue for activation.
- Modulating parasite MAPK activity in vitro directly affected host cell invasion, with activation increasing and inhibition decreasing infectivity.
Impact:
- The findings implicate ERK-type parasite kinases in T. gondii infectivity, suggesting they are critical for the invasion process.
- This research provides a foundation for developing novel therapeutic strategies targeting parasite kinases to combat toxoplasmosis.
- Identifying key molecular players in parasite invasion opens avenues for anti-parasitic drug development.