A C2 domain protein kinase initiates phagocytosis in the protozoan parasite Entamoeba histolytica

Abstract

Phagocytosis is a process whereby particles are taken in by cells through mechanisms super ficially similar to those for endocytosis. It serves a wide range of functions, from providing nutrition in unicellular organisms to initiation of both innate and adaptive immunity in vertebrates. In the protozoan parasite Entamoeba histolytica, it has an essential role in survival and pathogenesis. In this study, we show that EhC2PK, a C2 domain containing protein kinase, and the Ca 2 + and actin binding protein, EhCaBP1, are involved in the initiation of phagocytosis in E. histolytica. Conditional suppression of EhC2PK expression and overexpression of a mutant form reveals its role in the initiation of phagocytic cups. EhC2PK binds phosphatidylserine in the presence of Ca 2 + and thereby recruits EhCaBP1 and actin to the membrane. Identification of these proteins in phagocytosis is an important step in amoebic biology and these molecules could be the important targets for developing novel therapies against amoebiasis.

Autophosphorylation of Ser428 of EhC2PK Plays a Critical Role in Regulating Erythrophagocytosis in the Parasite Entamoeba histolytica

“…Our results strongly suggest a regulatory role of this region in kinase activity of EhC2PK. It is clear from our previous studies that EhC2PK is involved in the initiation of erythrophagocytosis in E. histolytica (6). The requirement of a functional kinase domain was evident when it was observed that overexpression of the kinase-dead mutant and the C2 domain alone led to impaired phagocytosis.…”

“…A few of the C2 domain containing PKCs have been shown to be involved in phagocytosis and regulation of actin polymerization (8,9). Our earlier observations have clearly indicated that the C2 domain of EhC2PK is necessary and sufficient to bind plasma membrane in the presence of Ca 2ϩ (6,10). Therefore, it is likely to provide an anchor for the formation of phagocytic machinery.…”

“…The protein kinase activity of EhC2PK is necessary for stabilization of the phagocytic cups and phagosome formation as overexpression of a kinase-dead mutant led to a reduction in these processes (6). To understand detailed mechanism of initiation of phagocytosis in E. histolytica we have characterized the kinase domain of EhC2PK.…”

“…We have recently identified and partially characterized a C2 domain-containing protein kinase (EhC2PK) 2 that is involved in the initiation of erythrophagocytosis in conjunction with EhCaBP1 and actin (6). It gets enriched at the site of RBC attachment until phagocytic cups are formed and stabilized.…”

Entamoeba histolytica: Host parasite interactions at the colonic epithelium

“…63 Trogocytosis shares similarities to Eh phagocytosis of cells including EhC2PK, a C2 domain containing protein kinase that initiates the phagocytic cup and actin recruitment. 64 Not surprisingly, interference with the cytoskeletal and microfilament network within Eh also inhibited trogocytosis. Host cells that were nibbled on also experienced irreversible intracellular calcium increases (Fig.…”