Parasporin-2 requires GPI-anchored proteins for the efficient cytocidal action to human hepatoma cells.
Parasporin-2 (PS2) is a Bacillus thuringiensis inclusion protein that reacts intensively with human hepatoma cells. This antitumour toxin oligomerizes at the cell surface via binding to lipid rafts, leading to the cell lysis with typical blebs around peripheral cells. We find here that glycosylphosphatidylinositol (GPI)-anchored proteins are involved in the cytocidal actions. Depletion of the cellular cholesterol and loss of sphingolipid in lipid rafts slightly decreased cytolysis by PS2. Beyond those, the cells temporally resisted PS2 with reduction of the toxin binding after GPI-anchored proteins were cleaved off by phosphatidylinositol-specific phospholipase C. PS2 and aerolysin showed individual cytocidal specificity while aerolysin's receptor is GPI-anchored proteins. When we confirmed expression of GPI-anchored proteins on four cell lines, showing different cytotoxicity by PS2, GPI-anchored proteins were evenly expressed on the cells. Therefore, PS2 requires a kind of GPI-anchored proteins for the effective cytolysis.
Kitada
Sakae
S
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka 812-8581, Japan. sakae@chem.kyushu-univ.jp
Abe
Yuichi
Y
Maeda
Toshitaka
T
Shimada
Hiroyasu
H
D000903:Antibiotics, Antineoplastic; D001427:Bacterial Toxins / Q000737:chemistry / Q000494:pharmacology; D015153:Blotting, Western; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D003593:Cytoplasm / Q000187:drug effects / Q000648:ultrastructure; D004731:Endotoxins / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D017261:Glycosylphosphatidylinositols / Q000737:chemistry*; D006801:Humans; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D052899:Pore Forming Cytotoxic Proteins / Q000737:chemistry / Q000494:pharmacology; D011506:Proteins / Q000737:chemistry*
D000903:Antibiotics, Antineoplastic; D001427:Bacterial Toxins; D004731:Endotoxins; D017261:Glycosylphosphatidylinositols; D052899:Pore Forming Cytotoxic Proteins; D011506:Proteins; C515506:parasporin-2, Bacillus thuringiensis; C032676:aerolysin