title: Toxoplasma gondii glycosylphosphatidylinositols are not involved in T. gondii-induced host cell survival.
abstract: Toxoplasma gondii is an intracellular parasite able to both promote and inhibit apoptosis. T. gondii renders infected cells resistant to programmed cell death induced by multiple apoptotic triggers. On the other hand, increased apoptosis of immune cells after in vivo infection with T. gondii may suppress the immune response to the parasite. Glycosylphosphatidylinositol (GPI)-anchored proteins dominate the surface of T. gondii tachyzoites and GPIs are involved in the pathogenicity of protozoan parasites. In this report, we determine if GPIs are responsible for inhibition or induction of host cell apoptosis. We show here that T. gondii GPIs fail to block apoptosis that was triggered in human-derived cells via extrinsic or intrinsic apoptotic pathways. Furthermore, characteristics of apoptosis, e.g. caspase-3/7 activity, phosphatidylserine exposition at the cell surface or DNA strand breaks, were not observed in the presence of T. gondii GPIs. These results indicate that T. gondii GPIs are not involved in survival or in apoptosis of host cells. This absence of effect on apoptosis could be a feature common to GPIs of other parasites.
authors.affiliation: Institut für Virologie, AG Parasitologie, Hans-Meerwein-Str. 2, D-35043 Marburg, Germany. debierre@staff.uni-marburg.de
authors.forename: Françoise
authors.initials: F
authors.lastname: Debierre-Grockiego
authors.forename: Diana
authors.initials: D
authors.lastname: Hippe
authors.forename: Ralph T
authors.initials: RT
authors.lastname: Schwarz
authors.forename: Carsten G K
authors.initials: CG
authors.lastname: Lüder
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology; D002236:Carbohydrate Conformation; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002460:Cell Line; D002470:Cell Survival; D045304:Cytochromes c / Q000378:metabolism; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000378:metabolism; D017261:Glycosylphosphatidylinositols / Q000737:chemistry / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D015394:Molecular Structure; D019311:Staurosporine / Q000378:metabolism; D014122:Toxoplasma / Q000472:pathogenicity / Q000502:physiology*; D014123:Toxoplasmosis; D019014:fas Receptor / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D017261:Glycosylphosphatidylinositols; D019014:fas Receptor; D045304:Cytochromes c; D053148:Caspase 3; D053179:Caspase 7; D019311:Staurosporine