Entamoeba invadens: Identification of ADF/cofilin and their expression analysis in relation to encystation and excystation

• Published in: Experimental parasitology Vol. 127; no. 1; pp. 195 - 201
• Main Authors: Makioka, Asao, Kumagai, Masahiro, Hiranuka, Kazushi, Kobayashi, Seiki, Takeuchi, Tsutomu
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 2011; Elsevier
• Subjects: actin; Actin cytoskeleton; Actin Depolymerizing Factors - chemistry; Actin Depolymerizing Factors - genetics; Actin Depolymerizing Factors - immunology; Actin Depolymerizing Factors - metabolism; ADF/cofilin; Amino Acid Sequence; Animals; antiserum; axenic culture; Biological and medical sciences; blood serum; cell membranes; cell movement; Cloning, Molecular; Cytochalasin D; Cytochalasin D - pharmacology; cytoskeleton; DNA, Protozoan - chemistry; Encystation; encystment; Entamoeba - chemistry; Entamoeba - classification; Entamoeba - genetics; Entamoeba - physiology; Entamoeba dispar; Entamoeba histolytica; Entamoeba invadens; Excystation; fluorescent antibody technique; Fundamental and applied biological sciences. Psychology; Gene Expression; genome; Immune Sera - immunology; Life cycle. Host-agent relationship. Pathogenesis; messenger RNA; Metazoa; methionine; molecular cloning; Nucleic Acid Synthesis Inhibitors - pharmacology; parasites; parasitology; phosphorylation; Phylogeny; Polymerase Chain Reaction; Protozoa; pseudopodia; Rabbits; Real-time RT-PCR; reverse transcriptase polymerase chain reaction; RNA, Messenger - metabolism; RNA, Protozoan - genetics; RNA, Protozoan - isolation & purification; Saccharomyces cerevisiae; Schizosaccharomyces pombe; Sequence Alignment; serine; trees; trophozoites; Real-time RT-PCR; Protozoa; Entamoeba invadens; ADF/cofilin; Encystation; Excystation; Cytochalasin D; Actin cytoskeleton; Lobosea; Parasite; Excystment; Polymerase chain reaction; Encystment; Cytochalasin; Actin; Cytoskeleton
• ISSN: 0014-4894; 1090-2449
• DOI: 10.1016/j.exppara.2010.07.018

The differentiation processes of excystation and encystation of Entamoeba are essential for infection and completion of their life-cycle, and the processes need cell motility and its control by actin cytoskeletal reorganization. This study investigated actin depolymerizing factor (ADF)/cofilin (Cfl) family proteins, which are important molecules in actin cytoskeletal reorganization, in Entamoeba invadens in relation to the encystation and excystation. Axenic culture systems were used to induce encystation and excystation. A homology search of the E. invadens genome database and molecular cloning identified three ADF/Cfl family proteins of the parasite (named for short as EiCfl-1, EiCfl-2, and EiCfl-3). This is different from other Entamoeba species, i.e. Entamoeba histolytica and Entamoeba dispar, each of which has only one ADF/Cfl family protein. These ADF/Cfl of E. invadens do not have Ser3 (serine locates third from first methionine), similar to E. histolytica, E. dispar, Saccharomyces cerevisiae and Schizosaccharomyces pombe, although the activity of ADF/Cfl is negatively regulated by phosphorylation of the Ser3 in metazoans. Phylogenetic analysis revealed that Entamoeba Cfl formed a distinctive clade that is separate from other organisms, and the branches of the tree were separated in two consistent with the presence and absence of Ser3. Rabbit anti-EiCfl-2 serum reacted with all recombinant EiCfls and EiCfl in lysates of cysts, trophozoites and metacystic amoebae. Immunofluorescence staining with this antiserum showed co-localization of EiCfl with actin beneath the cell membrane through the life stages. Both proteins proved to be rich in pseudopodia of trophozoites and metacystic amoebae. Real-time RT-PCR showed that mRNAs of EiCfl-2 and actins were highly expressed, but there were few mRNA of EiCfl-1 and EiCfl-3. Remarkably decreased mRNA levels were observed in EiCfl-2 and actins during encystation. All three EiCfls and actins became transcribed after the induction of excystation. The mRNAs of only EiCfl-1 and EiCfl-3 increased remarkably when the excystation was induced in the presence of cytochalasin D. These findings demonstrate that EiCfl-2 and actins co-localize beneath the cell membrane in trophozoites and cysts as well as metacystic amoebae being rich in pseudopodia, that EiCfl-1 and EiCfl-3 are expressed only after the induction of excystation, and that enhanced excystation by cytochalasin D is associated with high expression of EiCfl-1 and EiCfl-3.