Immunology and Reproduction Biology Laboratory & State Key Laboratory of Analytical Chemistry for Life Science, Medical School, Nanjing University, Nanjing, 210093, China; Jiangsu Key Laboratory of Molecular Medicine, Nanjing University, Nanjing, 210093, China.
Chemosphere. 2021 Feb;264(Pt 1):128440. doi: 10.1016/j.chemosphere.2020.128440. Epub 2020 Sep 25.
Microcystin-leucine-arginine (MC-LR) has been identified to be a hazardous material to cause hepatotoxicity. In this study, mice were exposed to MC-LR dissolved in drinking water at doses of 1, 10, 20 and 30 μg/L for 90 and 180 days, respectively. We validated MC-LR accelerated spermatid exfoliation and caused large vacuoles in testes, reducing sperm count and increasing percentage of morphologically abnormal sperm. Furthermore, we found MC-LR induced the apical ectoplasmic specialization (ES) disassembly by disrupting F-actin organization. Further studies identified that downregulation of Palladin, the actin crosslinking protein, might be associated with disassembly of the apical ES in mice testis following MC-LR exposure. We also confirmed that MC-LR disrupted the interaction between Palladin and other actin-related proteins and thus impeded the F-actin organization. Additionally, we found that autophagy initiated by AMPK/ULK1 signaling pathway mediated the degradation of Palladin in Sertoli cells challenged with MC-LR. Following exposure to MC-LR, reduced PP2A activity and upregulated expression of LKB1 and CAMKK2 could activate AMPK. In conclusion, these results revealed MC-LR induced the degradation of Palladin via AMPK/ULK1-mediated autophagy, which might result in the apical ES disorder and spermatid exfoliation from spermatogenic epithelium. Our work may provide a new perspective to understand MC-LR-induced male infertility.
微囊藻氨酸-亮氨酸-精氨酸（MC-LR）已被确定为一种具有肝毒性的有害物质。在这项研究中，将 MC-LR 溶解在饮用水中，分别以 1、10、20 和 30μg/L 的剂量给小鼠染毒 90 和 180 天。我们验证了 MC-LR 加速了精子细胞的脱落，并在睾丸中导致大的空泡，减少精子计数并增加形态异常精子的百分比。此外，我们发现 MC-LR 通过破坏 F-肌动蛋白组织扰乱顶外侧质特化（ES）的组装。进一步的研究表明，肌动蛋白交联蛋白 Palladin 的下调可能与 MC-LR 暴露后小鼠睾丸顶 ES 的解体有关。我们还证实，MC-LR 破坏了 Palladin 与其他肌动蛋白相关蛋白之间的相互作用，从而阻碍了 F-肌动蛋白的组织。此外，我们发现 AMPK/ULK1 信号通路介导的自噬起始介导了 Palladin 在受到 MC-LR 挑战的支持细胞中的降解。暴露于 MC-LR 后，减少的 PP2A 活性和上调的 LKB1 和 CAMKK2 的表达可以激活 AMPK。总之，这些结果表明，MC-LR 通过 AMPK/ULK1 介导的自噬诱导 Palladin 的降解，这可能导致顶外侧质特化的紊乱和精子细胞从生精上皮脱落。我们的工作可能为理解 MC-LR 诱导的男性不育提供了一个新的视角。
