Department of Physiology, University of Tübingen, Gmelinstr. 5, 72076 Tübingen, Germany.
Toxicology. 2011 Apr 28;283(1):24-31. doi: 10.1016/j.tox.2011.01.023. Epub 2011 Feb 3.
Beauvericin is a mycotoxin with antiviral, antibacterial, nematicidal, insecticidal, cytotoxic, and apoptotic activity. Similar to nucleated cells erythrocytes may undergo suicidal death or eryptosis, which is characterized by cell shrinkage and phosphatidylserine exposure at the erythrocyte surface. Eryptosis may be triggered by energy depletion leading to increase of cytosolic Ca²+ activity. The present study thus explored whether beauvericin is able to trigger eryptosis and influence eryptosis following energy depletion. Cell membrane scrambling was estimated from binding of annexin V to phosphatidylserine at the erythrocyte surface, cell volume from forward scatter in FACS analysis, cytosolic Ca²+ concentration from Fluo3 fluorescence, cytosolic ATP concentration from a luciferase-assay and ion channel activity with whole cell patch clamp. Exposure to beauvericin (≥ 5 μM) significantly decreased erythrocyte ATP concentration and increased cytosolic Ca²+ concentration as well as annexin V-binding. The effect of beauvericin on annexin V binding was significantly blunted by removal of extracellular Ca²+. Glucose depletion (48 h) was followed by, increase of Fluo3 fluorescence, decrease of forward scatter and increase of annexin V-binding. Beauvericin (≥ 1 μM) augmented the effect of glucose withdrawal on Fluo3 fluorescence and annexin V-binding, but significantly blunted the effect of glucose withdrawal on forward scatter, an effect paralleled by inhibition of Ca²+ activated K+ channels. The present observations disclose novel effects of beauvericin, i.e. stimulation of Ca²+ entry with subsequent cell membrane scrambling and inhibition of Ca²+ activated K+ channels with blunting of cell shrinkage.
伏马菌素是一种具有抗病毒、抗菌、杀线虫、杀虫、细胞毒性和细胞凋亡活性的真菌毒素。类似于有核细胞，红细胞可能会经历自杀性死亡或红细胞凋亡，其特征是细胞收缩和磷脂酰丝氨酸在红细胞表面暴露。细胞凋亡可能是由能量耗竭引起的，导致细胞内 Ca²+ 活性增加。因此，本研究探讨了伏马菌素是否能够引发红细胞凋亡，并在能量耗竭后影响红细胞凋亡。细胞膜的混乱程度可以通过在红细胞表面结合 Annexin V 来评估，细胞体积可以通过流式细胞术分析中的前向散射来评估，细胞内 Ca²+ 浓度可以通过 Fluo3 荧光来评估，细胞内 ATP 浓度可以通过荧光素酶测定来评估，离子通道活性可以通过全细胞膜片钳来评估。暴露于伏马菌素（≥5 μM）显著降低了红细胞 ATP 浓度，增加了细胞内 Ca²+ 浓度和 Annexin V 结合。去除细胞外 Ca²+ 显著减弱了伏马菌素对 Annexin V 结合的影响。葡萄糖耗竭（48 h）后，Fluo3 荧光增加，前向散射减少，Annexin V 结合增加。伏马菌素（≥1 μM）增强了葡萄糖耗竭对 Fluo3 荧光和 Annexin V 结合的影响，但显著减弱了葡萄糖耗竭对前向散射的影响，这种作用与钙激活钾通道的抑制相平行。本研究揭示了伏马菌素的新作用，即刺激 Ca²+ 内流，随后导致细胞膜混乱，并抑制钙激活钾通道，从而阻止细胞收缩。
