Department of Pharmacy Practice, Tri-Service General Hospital, Taipei 114, Taiwan.
School of Pharmacy, National Defense Medical Center, Taipei 114, Taiwan.
Chem Res Toxicol. 2020 Apr 20;33(4):903-914. doi: 10.1021/acs.chemrestox.9b00437. Epub 2020 Mar 27.
Methylenedioxymethamphetamine (MDMA) is a psychostimulant with high abuse potential and severe neurotoxicity. According to our previous study, MDMA promotes autophagosome accumulation and contributes to cell death in cultured cortical and serotonergic neurons. However, the detailed mechanism underlying autophagy dysfunction remains unclear. Lysosomes play an important role in autophagic degradation. The present study aimed to examine the role of lysosomal function in autophagic flux in neuronal cultures exposed to MDMA. We showed that MDMA induced enlarged vesicles that accumulate in SH-SY5Y neuroblastoma cells. In addition, we demonstrated that MDMA stimulated dynamin-dependent but clathrin-independent endocytosis, which might contribute to vacuole expansion. Morphological and Western blot analyses revealed that MDMA induced lysosomal swelling, whereas the activity of the lysosomal hydrolytic enzymes cathepsin B and cathepsin D was decreased in SH-SY5Y and cultured cortical neurons, which might lead to autophagosome accumulation and autophagic degradation blockage. Intriguingly, inactivation of cathepsins B and D led to cell death and autophagy-lysosomal dysregulation, which mimicked MDMA-induced neurotoxicity. Consequently, impairment of lysosomal proteolysis and blockage of autophagy degradation contributed to MDMA-induced neurotoxicity in neuronal cultures.
亚甲二氧基甲基苯丙胺（MDMA）是一种具有高滥用潜力和严重神经毒性的精神兴奋剂。根据我们之前的研究，MDMA 促进自噬体的积累，并导致培养的皮质和血清素能神经元死亡。然而，自噬功能障碍的详细机制尚不清楚。溶酶体在自噬降解中起重要作用。本研究旨在探讨溶酶体功能在暴露于 MDMA 的神经元培养物中自噬流中的作用。我们表明，MDMA 诱导了在 SH-SY5Y 神经母细胞瘤细胞中积累的扩大囊泡。此外，我们证明 MDMA 刺激了依赖于动力蛋白但不依赖于网格蛋白的内吞作用，这可能有助于囊泡的扩张。形态学和 Western blot 分析表明，MDMA 诱导溶酶体肿胀，而溶酶体水解酶组织蛋白酶 B 和组织蛋白酶 D 的活性在 SH-SY5Y 和培养的皮质神经元中降低，这可能导致自噬体的积累和自噬降解的阻断。有趣的是，组织蛋白酶 B 和 D 的失活导致细胞死亡和自噬溶酶体失调，模拟了 MDMA 诱导的神经毒性。因此，溶酶体蛋白水解的损伤和自噬降解的阻断导致神经元培养物中 MDMA 诱导的神经毒性。
