Profiling of lincRNAs and differential regulatory mechanisms in response to nanoplastic toxicity at environmentally relevant concentrations in Caenorhabditis elegans

Polystyrene nanoplastics (PS-NPs) at environmentally relevant concentrations have been shown to be toxic to living organisms, but the role of long noncoding RNAs (lncRNAs) in their toxicity regulation is not yet clear. Using Caenorhabditis elegans (C. elegans) as a model organism, we investigate the mechanisms and roles of lncRNAs in PS-NPs toxicity at environmentally relevant concentrations. In this study, L1 larvae were exposed to 1-100 µg/L of 50 nm PS-NPs for 72 h, and high-throughput transcriptome sequencing was performed. Exposure to PS-NPs at concentrations of 10 µg/L, which is in the range of environmentally relevant concentrations of nanoplastics, or higher can lead to increased reactive oxygen species (ROS) production and decreased locomotion behavior in C. elegans, yet no significant toxic effects were observed for the leachate. The sequencing results revealed significant changes in G protein-coupled receptors and long intergenic noncoding RNAs (lincRNAs), which warranted further investigation. Additionally, a CRISPR-based knockout (KO) mutant library of C. elegans lincRNAs was employed for in-depth mechanistic studies. The findings indicate that multiple lincRNAs are involved in the regulatory response to the toxic effects of PS-NPs. Compared to wild-type nematodes, linc-7, linc-9, linc-13, linc-21, linc-24, linc-49, linc-61, and linc-169 KO nematodes exhibited increased sensitivity to the toxicity of PS-NPs, while linc-11 and linc-50 nematodes showed resistance. Notably, our results indicate that the transcription process of linc-11, rather than its mature transcripts, played a crucial role in the response to PS-NPs. This is evidenced by the differing phenotypes observed in RNA interference (RNAi) knockdown (KD) and CRISPR KO nematodes following exposure to PS-NPs. Our results suggest that transcriptional regulation involving lncRNAs is integral to the organism's response to PS-NPs.