Poly(ADP-ribose)Glycohydrolase activity is important for lysosome formation during Trypanosoma cruzi invasion

Abstract

Chagas´ disease stands as one of the main public health problems in Latin America. T. cruzi, protozoan parasite responsible for this disease, has a complex life cycle comprising several stages that allow it to multiply and disseminate. During the cell invasion step, the parasite modulates several metabolic pathways in the host cell; therefore, drugs that operate on these pathways could be used with therapeutic aims. Signaling though PI3k/Akt elicited in the host cell during T. cruzi infection. Activation of this pathway is important since it has anti-apoptotic effects that operate in favor of the infection and is also crucial for the regulation of the lysosome dependent and independent invasion mechanisms. Recently, it has been reported that Poly(ADP-ribose)Glycohydrolase (PARG) participates in the regulation of the PI3k/Akt route by downregulating Akt phosphorylation in cancer cells. In our infection model, PARG inhibition by DEA 1 μM or silencing by iRNA (shPARG) in Vero cells, the % of phosphorylated Akt is not altered when compared to Wild Type infected cells, but the upregulation of Akt levels on Wild Type (35% at 15 min and 80% at 6 h PI) cells could not be observed in cells where PARG activity is absent. Lysosome formation in response to parasitic infection is also altered when Vero cell PARG is inhibited or silenced: at 1 h PI, LAMP-1 (lysosome marker) signaling diminishes in DEA 1 μM-treated or shPARG cells in comparison to Wild Type cells. The reduction in lysosome density can also been observed in the absence of infection, indicating that lysosome formation regulation by PARG might be operating also in physiological conditions. Previous results obtained by our group showed that PARG inhibition led to a marked decrease in T. cruzi infection in vitro. These new findings could indicate that the downregulation of the lysosome invasion pathway could partially account for the reduction in T. cruzi infection when PARG activity is absent.