abnormalities of endocytosis, phagocytosis, and development process in dictyostelium cells that over-express acanthamoeba castellanii metacaspase protein.

background : acanthamoeba castellanii forms a resistant cyst that protects the para-site against the host’s immune response. acanthamoeba type-i metacaspase (acmcp) is a caspase-like protein that has been found to be expressed during the encysta-tions. dictyostelium discoideum is an organism closely related to acanthamoeba useful for studying the molecular function of this protozoan caspase-like protein. methods: the full length of acmcp and a mutated version of the same gene, which lacks the proline rich n-terminal region (acmcp-dpr), were cloned into the pdneo2a-gfp vector separately. the pdneo2a-gfp-acmcp and pdneo2a-gfp-acmcp-dpr were electro-transfected into wild type d . discoideum cells to create cell lines that over-expressed acmcp or acmcp-dpr. results : both cell lines that over-expressed acmcp and acmcp-dpr showed a sig-nificant increase in the fluid phase internalization and phagocytosis rate compared to the control cells. additionally, the cells expressing the acmcp-dpr mutant were unable to initiate early development and failed to aggregate or form fruiting bodies under starvation conditions, whereas acmcp over-expressing cells showed the op-posite phenomena. quantitative cell death analysis provided additional support for these findings.   conclusion : acmcp is involved in the processes of endocytosis and phagocytosis. in addition, the proline rich region in acmcp is important for cellular development in dictyostelium . given its important role in the development process, metacaspase protein is proposed as a candidate drug target against infections caused by a. castel-lanii .