Original Article Abnormalities of Endocytosis, Phagocytosis, and Development Process in Dictyostelium Cells That Over-Express

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 bodie