Kitada Sakae, Abe Yuichi, Shimada Hiroyasu, Kusaka Yoshitomo, Matsuo Yoko, Katayama Hideki, Okumura Shiro, Akao Tetsuyuki, Mizuki Eiichi, Kuge Osamu, Sasaguri Yasuyuki, Ohba Michio, Ito Akio
Department of Chemistry, Faculty of Science, Kyushu University, Fukuoka 812-8581, Japan.
J Biol Chem. 2006 Sep 8;281(36):26350-60. doi: 10.1074/jbc.M602589200. Epub 2006 Jun 29.
Parasporin-2, a new crystal protein derived from noninsecticidal and nonhemolytic Bacillus thuringiensis, recognizes and kills human liver and colon cancer cells as well as some classes of human cultured cells. Here we report that a potent proteinase K-resistant parasporin-2 toxin shows specific binding to and a variety of cytocidal effects against human hepatocyte cancer cells. Cleavage of the N-terminal region of parasporin-2 was essential for the toxin activity, whereas C-terminal digestion was required for rapid cell injury. Protease-activated parasporin-2 induced remarkable morphological alterations, cell blebbing, cytoskeletal alterations, and mitochondrial and endoplasmic reticulum fragmentation. The plasma membrane permeability was increased immediately after the toxin treatment and most of the cytoplasmic proteins leaked from the cells, whereas mitochondrial and endoplasmic reticulum proteins remained in the intoxicated cells. Parasporin-2 selectively bound to cancer cells in slices of liver tumor tissues and susceptible human cultured cells and became localized in the plasma membrane until the cells were damaged. Thus, parasporin-2 acts as a cytolysin that permeabilizes the plasma membrane with target cell specificity and subsequently induces cell decay.
副孢子蛋白-2是一种源自非杀虫且非溶血的苏云金芽孢杆菌的新型晶体蛋白，可识别并杀死人类肝癌和结肠癌细胞以及某些类型的人类培养细胞。在此我们报告，一种高效的抗蛋白酶K副孢子蛋白-2毒素对人类肝癌细胞表现出特异性结合及多种杀细胞作用。副孢子蛋白-2 N端区域的切割对毒素活性至关重要，而C端消化对于快速的细胞损伤是必需的。蛋白酶激活的副孢子蛋白-2诱导了显著的形态改变、细胞起泡、细胞骨架改变以及线粒体和内质网碎片化。毒素处理后，质膜通透性立即增加，大多数细胞质蛋白从细胞中泄漏，而线粒体和内质网蛋白则保留在中毒细胞中。副孢子蛋白-2选择性地结合肝肿瘤组织切片中的癌细胞和敏感的人类培养细胞，并定位于质膜，直至细胞受损。因此，副孢子蛋白-2作为一种溶细胞素，以靶细胞特异性使质膜通透化，随后诱导细胞衰变。
