RESEARCH ARTICLE Small GTPase Rab21 Mediates Fibronectin Induced Actin Reorganization in Entamoeba histolytica: Implications in Pathogen Invasion

The protozoan parasite Entamoeba histolytica causes a wide spectrum of intestinal infec-tions. In severe cases, the trophozoites can breach the mucosal barrier, invade the intesti-nal epithelium and travel via the portal circulation to the liver, where they cause hepatic abscesses, which can prove fatal if left untreated. The host Extra Cellular Matrix (ECM) plays a crucial role in amoebic invasion by triggering an array of cellular responses in the parasite, including induction of actin rich adhesion structures. Similar actin rich protrusive structures, known as ‘invadosomes’, promote chemotactic migration of the metastatic can-cer cells and non-transformed cells by remodeling the ECM. Recent studies showed a cen-tral role for Rab GTPases, the master regulators of vesicular trafficking, in biogenesis of invadosomes. Here, we showed that fibronectin, a major host ECM component induced actin remodeling in the parasite in a Rab21 dependent manner. The focalized actin struc-tures formed were reminiscent of the mammalian invadosomes. By using various ap-proaches, such as immunofluorescence confocal microscopy and scanning electron microscopy, along with in vitro invasion assay and matrix degradation assay, we show tha