Receptors for Phagocytosis and Trogocytosis in Entamoeba histolytica

In the protozoan parasite Entamoeba histolytica, phagocytosis is considered to be indispensable for its parasitic lifestyle, and centrally involved in the pathogenesis. Currently, two modes of target internalization that can be differentiated at phenomenal and molecular levels have been demonstrated in E. histolytica: phagocytosis and trogocytosis. In phagocytosis, E. histolytica ingests a dead mammalian cell or an undeformable microorganism such as bacteria and fungi, as a whole. In contrast, in trogocytosis, live cells are nibbled (chewed) and ingested as fragments. It has been reported in E. histolytica that trogocytosis, not phagocytosis, is involved in immune evasion from complement attack via presenting cell surface membrane proteins acquired from host cells onto the amebic surface. Mechanistic differences at molecular levels between phagocytosis and trogocytosis have been only partially demonstrated. Only proteins known to differentiate these processes are a set of kinases, AGCK1 and AGCK2. However, what triggers phagocytosis versus trogocytosis remains largely unknown. In model organisms, it is well established that receptor for the prey is the key that regulates phagocytic internalization and the following signaling events defined by the prey. To get insights into receptor candidates for phagocytosis and trogocytosis, here we summarize previously identified potential receptors and surface molecules involved in adhesion and phagocytosis/trogocytosis in E. histolytica.