Ceramide synthase 2 knockdown suppresses trophozoite growth, migration, in vitro encystment and excystment of Entamoeba invadens.

Entamoeba invadens is the protozoan which causes multiple damages in reptiles and is considered a prototype for the study of the Entamoeba encystment/excystment in vitro. Here we report that EinCerS2 knockdown promoted decrease in sphingomyelin (SM) subspecies with long-chain fatty acids (24:0) down to 50% but increase sphingolipids with short-chain fatty acids (16:0) up to three times in both trophozoites and cysts of E. invadens. EinCerS2 silencing also resulted in decreased trophozoites' movement, proliferation, cysts formation, and trophozoites hatched after excystment. By immunofluorescence assays, a polyclonal antibody against EinCerS2 detected the enzyme in the cytoplasm of E. invadens trophozoites, colocalizing with Endoplasmic Reticulum-resident cognate EiSERCA. Interestingly, EinCerS2 was redistributed close to the plasma membrane during encystation, suggesting that the generation of diacylglycerol (DAG) via synthesis of sphingolipids and the activation protein kinase C might participate in the encystment process of E. invadens.