Nuclear-cytoplasmic trafficking of
proteins is a highly regulated process that modulates multiple biological processes in eukaryotic cells. In Giardia lamblia, shuttling has been described from the cytoplasm to nuclei of
proteins during the
biological cell cycle of the parasite. This suggests that a mechanism of nucleocytoplasmic transport is present and functional in G. lamblia. By means of computational biology analyses, we found that there are only two genes for nuclear transport in this parasite, named
Importin α and
Importin β. When these transporters were overexpressed, both localized close to the nuclear envelope, and no change was observed in trophozoite growth rate. However, during the encystation process, both transporters induced an increase in the number of
cysts produced.
Importazole and
Ivermectin, two known specific inhibitors of
importins, separately influenced the encysting process by inducing an arrest in the trophozoite stage that prevents the production of
cysts. This effect was more noticeable when
Ivermectin, an anti-parasitic
drug, was used. Finally, we tested whether the
enzyme arginine deiminase, which shuttles from the cytoplasm to the nuclei during encystation, was influenced by these transporters. We found that treatment with each of the inhibitors abrogates
arginine deiminase nuclear translocation and favors perinuclear localization. This suggests that
Importin α and
Importin β are key transporters during the encystation process and are involved, at least, in the transport of
arginine deiminase into the nuclei. Considering the effect produced by
Ivermectin during growth and encystation, we postulate that this
drug could be used to treat
giardiasis.