BIOTEC der TU Dresden, 01307 Dresden, Germany.
J Biol Chem. 2011 Oct 28;286(43):37768-77. doi: 10.1074/jbc.M111.281592. Epub 2011 Sep 1.
Pore-forming toxins have evolved to induce membrane injury by formation of pores in the target cell that alter ion homeostasis and lead to cell death. Many pore-forming toxins use cholesterol, sphingolipids, or other raft components as receptors. However, the role of plasma membrane organization for toxin action is not well understood. In this study, we have investigated cellular dynamics during the attack of equinatoxin II, a pore-forming toxin from the sea anemone Actinia equina, by combining time lapse three-dimensional live cell imaging, fluorescence recovery after photobleaching, FRET, and fluorescence cross-correlation spectroscopy. Our results show that membrane binding by equinatoxin II is accompanied by extensive plasma membrane reorganization into microscopic domains that resemble coalesced lipid rafts. Pore formation by the toxin induces Ca(2+) entry into the cytosol, which is accompanied by hydrolysis of phosphatidylinositol 4,5-bisphosphate, plasma membrane blebbing, actin cytoskeleton reorganization, and inhibition of endocytosis. We propose that plasma membrane reorganization into stabilized raft domains is part of the killing strategy of equinatoxin II.
孔形成毒素通过在靶细胞中形成孔来诱导膜损伤，从而改变离子稳态并导致细胞死亡。许多孔形成毒素将胆固醇、神经鞘脂或其他筏成分用作受体。然而，对于毒素作用的质膜组织的作用尚不清楚。在这项研究中，我们通过结合延时三维活细胞成像、光漂白后荧光恢复、FRET 和荧光相关光谱技术，研究了海葵 Actinia equina 来源的孔形成毒素 equinatoxin II 攻击期间的细胞动力学。我们的结果表明，equinatoxin II 的膜结合伴随着广泛的质膜重组成类似于融合脂质筏的微观域。毒素形成孔会诱导 Ca(2+)进入细胞质，同时伴随着磷脂酰肌醇 4,5-二磷酸的水解、质膜起泡、肌动蛋白细胞骨架重组和内吞作用抑制。我们提出，质膜重组为稳定的筏域是 equinatoxin II 杀伤策略的一部分。
