Single-cell RNA sequencing reveals adverse effects of paraquat on the fate commitment of murine neural stem cells

Paraquat (PQ), widely used as an agricultural herbicide, is a known neurotoxicant and linked to neurodegenerative diseases including Parkinson's disease. However, the mechanisms of PQ neurotoxicity remain to be determined. Herein, we explored the PQ neurotoxicity by focusing on its effect during murine neural stem cell (mNSC) differentiation. Based on our extensive single-cell RNA sequencing (scRNA-seq) analyses, we classified the differentiated mNSCs into eight cell subtypes, namely immature neuron, NSC, astrocyte, Purkinje cell, neuroblast, ependymal cell, OPC, and oligodendrocyte, and obtained unique transcriptome in each cell type. Significantly, PQ exposure changed the proportions of these subtypes, with decreased neurons and increased astrocytes. Such changes suggested PQ impacting neurogenesis for neurotoxicity. Besides, we analyzed the unique transcript signature (differentially expressed genes) in each cell subtype and unveiled PQ-altered cell-specific-responses in immature neurons. PQ increased intracellular and mitochondrial reactive oxygen species (ROS) in a dose-dependent manner. Intriguingly, pretreatment with mitochondria-targeted antioxidant MitoTEMPO ameliorated PQ-altered neuronal reduction. In addition, PQ dysregulated cell-to-cell communications. Taken together, our results showed that PQ altered differentiation of mNSCs and ROS played a key role in PQ-altered neuronal reduction. This study provided new insights into better understanding the neurotoxicity of PQ.