MDM2 upregulation induces mitophagy deficiency via Mic60 ubiquitination in fetal microglial inflammation and consequently neuronal DNA damage caused by exposure to ZnO-NPs during pregnancy

https://doi.org/10.1016/j.jhazmat.2023.131750Get rights and content
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Highlights

  • ZnO-NPs induced developmental toxicity in fetal brain tissue during pregnancy.

  • Microglia were the target cells of ZnO-NPs, which further induced neuronal DNA damage through paracrine inflammatory factors.

  • ZnO-NPs induced microglial mitophagy defect by disrupting mitochondrial homeostasis.

  • ZnO-NPs induced excess mtROS generation by downregulation of Mic60.

  • MDM2 was a key enzyme that promoted the ubiquitination and degradation of Mic60.

Abstract

During pregnancy, the human body is quite vulnerable to external stimuli. Zinc oxide nanoparticles (ZnO-NPs) are widely used in daily life, and they enter the human body via environmental or biomedical exposure, thus having potential risks. Although accumulating studies have demonstrated the toxic effects of ZnO-NPs, few studies have addressed the effect of prenatal ZnO-NP exposure on fetal brain tissue development. Here, we systematically studied ZnO-NP-induced fetal brain damage and the underlying mechanism. Using in vivo and in vitro assays, we found that ZnO-NPs could cross the underdeveloped bloodsingle bondbrain barrier and enter fetal brain tissue, where they could be endocytosed by microglia. ZnO-NP exposure impaired mitochondrial function and induced autophagosome overaccumulation by downregulation of Mic60, thus inducing microglial inflammation. Mechanistically, ZnO-NPs increased Mic60 ubiquitination by activating MDM2, resulting in imbalanced mitochondrial homeostasis. Inhibition of Mic60 ubiquitination by MDM2 silencing significantly attenuated the mitochondrial damage induced by ZnO-NPs, thereby preventing autophagosome overaccumulation and reducing ZnO-NP-mediated inflammation and neuronal DNA damage. Our results demonstrate that ZnO-NPs are likely to disrupt mitochondrial homeostasis, inducing abnormal autophagic flux and microglial inflammation and secondary neuronal damage in the fetus. We hope the information provided in our study will improve the understanding of the effects of prenatal ZnO-NP exposure on fetal brain tissue development and draw more attention to the daily use of and therapeutic exposure to ZnO-NPs among pregnant women.

Key words

Zinc oxide nanoparticles
Neurodevelopmental toxicity
Paracrine effect
Mitochondrial homeostasis
Oxidation respiratory chain

Data availability

Data will be made available on request.

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1

These authors contributed equally to this work and should be considered co-first authors.