EhRab21 mobilization during erythrophagocytosis in Entamoeba histolytica.

Rab proteins are present in all eukaryotic lineages and regulate vesicular trafficking. Entamoeba histolytica has approximately 100 genes encoding Rab proteins, among which 16 have homology with human Rab proteins. Human Rab21 participates in integrin recycling, and thus amoebic Rab21 was believed to regulate the mobilization of Ehβ1FNR (integrin-like fibronectin receptor related with human integrin β1). We analyzed the distribution of EhRab21 using a polyclonal antibody produced with a specific peptide against the amoebic Rab protein, using confocal microscopy and specific probes for different organelles. EhRab21 was not associated with Ehβ1FNR in fibronectin-stimulated trophozoites. However, EhRab21 was relocalized to lysosomes in erythrophagocytosis assays and was also found in Golgi-positive structures and the nuclear periphery. These results suggest that EhRab21, unlike its human homologue, is not present in the recycling pathway. However, according to the results, EhRab21 may regulate the trafficking between lysosomes and the Golgi apparatus.