Integrated high-throughput small RNA and transcriptome sequencing unveil the shape-dependent toxicity of nano-alumina in rat astrocytes

Background The large-scale applications of alumina nanoparticles (Al 2 O 3 -NPs), one of the most important NPs in the global market, are causing severe damages to the environment and human health. Our previous research has revealed a critical role of nanoparticle morphology (e.g., flake and rod) in determining the toxic potencies of Al 2 O 3 -NPs, where nanorods demonstrated a significantly stronger toxic response than that of nanoflakes. However, their underlying mechanisms have not been completely elucidated yet. In the present study, we evaluated and compared the potential toxicological mechanisms of two shapes of γ-Al 2 O 3 -NPs (flake versus rod) by measuring miRNA and mRNA profiles of astrocytes in rat cerebral cortex, ex vivo. Results A total of 269 mRNAs and 122 miRNAs, 180 mRNAs and 116 miRNAs were differentially expressed after nanoflakes or nanorods exposure, respectively. Among them, 55 miRNAs (e.g., miR-760-5p, miR-326-3p, and miR-35) and 105 mRNAs (e.g., Kdm4d , Wdr62 , and Rps6 ) showed the same trend between the two shapes. These miRNAs and mRNAs were mainly involved in apoptosis, inflammatory pathways (e.g., NF-kappa B), carcinogenic pathways (e.g., MAPK, p53, Notch, Rap1, and Ras), and cellular lipid metabolisms (e.g., glycerolipid metabolism, sphingolipid, and ether lipid metabolism). However, the remaining miRNAs and mRNAs either showed an opposite trend or only changed by a particular shape. Nanorods could specifically alter the changes of PI3K/Akt, AMPK and TNF pathways, cell cycle, and cellular senescence, while nanoflakes caused the changes of Toll and lmd signaling pathways. Conclusions Combined with previous research results, we further revealed the potential biomolecular mechanisms leading to the stronger toxicity of nanorods than that of nanoflakes, and multi-omics is a powerful approach to elucidate morphology-related mode of actions.