Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Währinger Str. 38-40, 1090 Vienna, Austria; Vienna Doctoral School in Chemistry, Faculty of Chemistry, University of Vienna, Währinger Str. 42, 1090 Vienna Austria.
Department of Food Chemistry and Toxicology, Faculty of Chemistry, University of Vienna, Währinger Str. 38-40, 1090 Vienna, Austria.
Aquat Toxicol. 2024 Nov;276:107080. doi: 10.1016/j.aquatox.2024.107080. Epub 2024 Sep 3.
Prymnesins, produced by the haptophyte Prymnesium parvum, are considered responsible for fish kills when this species blooms. Although their toxic mechanism is not fully understood, membrane disruptive properties have been ascribed to A-type prymnesins. Currently it is suggested that pore-formation is the underlying cause of cell disruption. Here the hypothesis that A-, B-, and C-type prymnesins interact with sterols in order to create pores was tested. Prymnesin mixtures containing various analogs of the same type were applied in hemolysis and cytotoxicity assays using Atlantic salmon Salmo salar erythrocytes or rainbow trout RTgill-W1 cells. The hemolytic potency of the prymnesin types reflected their cytotoxic potential, with approximate concentrations reaching 50 % hemolysis (HC) of 4 nM (A-type), 54 nM (C-type), and 600 nM (B-type). Variabilities in prymnesin profiles were shown to influence potency. Prymnesin-A (3 Cl) + 2 pentose + hexose was likely responsible for the strong toxicity of A-type samples. Co-incubation with cholesterol and epi-cholesterol pre-hemolysis reduced the potential by about 50 % irrespective of sterol concentration, suggesting interactions with sterols. However, this effect was not observed in RTgill-W1 toxicity. Treatment of RTgill-W1 cells with 10 µM lovastatin or 10 µM methyl-β-cyclodextrin-cholesterol modified cholesterol levels by 20-30 %. Regardless, prymnesin cytotoxicity remained unaltered in the modified cells. SPR data showed that B-type prymnesins likely bound with a single exponential decay while A-types seemed to have a more complex binding. Overall, interaction with cholesterol appeared to play only a partial role in the cytotoxic mechanism of pore-formation. It is suggested that prymnesins initially interact with cholesterol and stabilize pores through a subsequent, still unknown mechanism possibly including other membrane lipids or proteins.
甲藻素由甲藻属微小甲藻产生，当这种物种大量繁殖时，被认为是鱼类死亡的罪魁祸首。尽管其毒性机制尚未完全阐明，但已将膜破坏特性归因于 A 型甲藻素。目前，人们认为孔形成是细胞破坏的根本原因。在这里，测试了 A 型、B 型和 C 型甲藻素与固醇相互作用以形成孔的假设。使用大西洋鲑鱼（Salmo salar）红细胞或虹鳟鱼（RTgill-W1）细胞，在溶血和细胞毒性测定中应用了含有同一类型各种类似物的甲藻素混合物。甲藻素类型的溶血效力反映了它们的细胞毒性潜力，约 50％溶血（HC）的近似浓度为 4 nM（A 型），54 nM（C 型）和 600 nM（B 型）。甲藻素谱的可变性表明其对效力有影响。甲藻素-A（3 Cl）+ 2 戊糖+己糖可能是 A 型样品强毒性的原因。预溶血时与胆固醇和表-胆固醇共孵育，不论胆固醇浓度如何，都会降低约 50％的潜力，表明与固醇相互作用。但是，在 RTgill-W1 毒性中未观察到这种作用。用 10 μM 洛伐他汀或 10 μM 甲基-β-环糊精胆固醇处理 RTgill-W1 细胞，胆固醇水平降低了 20-30％。无论如何，在修饰的细胞中，甲藻素的细胞毒性仍保持不变。SPR 数据表明，B 型甲藻素可能以单指数衰减的方式结合，而 A 型甲藻素似乎具有更复杂的结合方式。总体而言，与胆固醇的相互作用似乎仅在孔形成的细胞毒性机制中起部分作用。据推测，甲藻素最初与胆固醇相互作用，并通过随后的未知机制（可能包括其他膜脂质或蛋白质）稳定孔。
