Manganese induces autophagy dysregulation: The role of S-nitrosylation in regulating autophagy related proteins in vivo and in vitro

• Published in: The Science of the total environment 2020-01, Vol.698, p.134294, Article 134294
• Main Authors: Ma, Zhuo, Wang, Can, Liu, Chang, Yan, Dong-Ying, Tan, Xuan, Liu, Kuan, Jing, Meng-Jiao, Deng, Yu, Liu, Wei, Xu, Bin
• Format: Article
• Language: English
• Subjects: Animals; Autophagy; Autophagy dysregulation; Autophagy-Related Proteins; Humans; Manganese - toxicity; Mice; Neurotoxicity; Nitric Oxide Synthase Type II; Nitrosative stress; Proto-Oncogene Proteins c-bcl-2; Signal Transduction - drug effects; TOR Serine-Threonine Kinases; Toxicity Tests
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2019.134294

Exposure to excess levels of manganese (Mn) may lead to nitrosative stress and neurotoxic effects on the central nervous system (CNS). The dysfunction of autophagy correlates with Mn-induced nitrosative stress; however, the exact mechanism of Mn-mediated autophagy dysfunction is still unclear. Three S-nitrosylated target proteins, namely, JNK, Bcl-2, and IKKβ, were classified as the pivotal signaling pathway mediators that could play a role in the regulation of autophagy. To reveal whether these three proteins were involved in Mn-mediated autophagy dysregulation, we studied the effects of Mn on C57/BL6 mice and human neuroblastoma cells. Exposing the mice or cells, to 300 μmol/kg or 200 μM Mn, inhibited the degradation system of the autophagy-lysosome pathway. Additionally, in Mn-treated mice or cells, S-nitrosylated JNK, Bcl-2, and IKKβ increased while the level of their phosphorylation reduced. The interaction of Beclin1 and Bcl-2 significantly increased in response to 200 μM Mn, whereas the decrease in phosphorylation of AMPK activated the mTOR pathway. We then used 20 μM 1400 W, an iNOS-specific inhibitor, to neutralize the nitrosative stress induced by Mn. Our results show that 1400 W reduced the S-nitrosylated JNK, Bcl-2, and Ikkβ and relieved their downstream signaling molecular functions. Moreover, pretreatment with 20 μM 1400 W alleviated Mn-induced autophagic dysregulation and nerve cell injury. These findings revealed that S-nitrosylated JNK, Bcl-2, and IKKβ are crucial signaling molecules in the Mn-mediated autophagic dysfunction. [Display omitted] •Mn-induced nitrosative stress resulted in autophagic dysregulation.•S-nitrosylated Bcl-2 increased the interaction of Beclin1 with Bcl-2.•S-nitrosylated Ikkβ disturbed autophagy by Ikkβ/AMPK/mTOR pathway.•1400 W could relieve Mn-induced autophagic dysregulation and cell injury.