Identification of potential circRNA-miRNA-mRNA regulatory networks in response to graphene quantum dots in microglia by microarray analysis

Along with the increasing application of graphene quantum dots (GQDs) in the fields of biomedicine and neuroscience, it is important to assess the probably adverse effects of GQDs in the central nervous system (CNS) but their underlying toxic mechanisms is still unclear. In this study, we evaluate the molecular mechanisms associated with circular RNAs (circRNAs) of nitrogen-doped GQDs (N-GQDs) and amino-functionalized GQDs (A-GQDs) damaging the cell viability and cellular structure in microglia by an integrative analysis of RNA microarray. The differentially expressed circRNA (DEcircRNAs)-miRNAdifferentially expressed mRNA (DEmRNAs) regulatory networks were conducted in BV2 microglial cells treated with 25 mu g/mL N-GQDs, 100 mu g/mL N-GQDs and 100 mu g/mL A-GQDs. Based on that, the protein-coding genes in each ceRNA network were collected to do bio-functional analysis to evaluate signaling pathways that were indirectly mediated by circRNAs. Some pathways that could play indispensable roles in the neurotoxicity of N-GQDs or both two kinds of GQDs were found. Low-dosed N-GQDs exposure mainly induced inflammatory action in microglia, while high-dosed N-GQDs and A-GQDs exposure both affect olfactory transduction and GABAergic synapse. Meanwhile, several classical signaling pathways, including mTOR, ErbB and MAPK, could make diverse contributions to the neurotoxicity of both two kinds of GQDs. These circRNAs could be toxic biomarkers or protective targets in neurotoxicity of GQDs. More importantly, they emphasized the necessity of comprehensive analysis of latent molecular mechanisms through epigenetics approaches in biosafety assessment of graphene-based nanomaterials.

Automated summary

The study identified the importance of circRNAs in the neurotoxicity of nitrogen-doped and amino-functionalized graphene quantum dots, revealing different effects at low and high doses. Additionally, classical signaling pathways like mTOR, ErbB, and MAPK were found to contribute to the neurotoxicity of both types of graphene quantum dots. These findings emphasize the necessity of a comprehensive analysis of molecular mechanisms through epigenetics approaches in biosafety assessment of graphene-based nanomaterials.