Silver Nanoparticles Exposure Impairs Cardiac Development by Suppressing the Focal Adhesion Pathway in Zebrafish.

INTRODUCTION: The potential toxic effects of wastewater discharges containing silver nanoparticles (AgNPs) and their release into aquatic ecosystems on aquatic organisms are becoming a major concern for environmental and human health. However, the potential risks of AgNPs to aquatic organisms, especially for cardiac development by Focal adhesion pathway, are still poorly understood. METHODS: The cardiac development of various concentrations of AgNPs in zebrafish were examined using stereoscopic microscope. The expression levels of cardiac development-related genes were analyzed by qRT-PCR and Whole-mount in situ hybridization (WISH). In addition, Illumina high-throughput global transcriptome analysis was performed to explore the potential signaling pathway involved in the treatment of zebrafish embryos by AgNPs after 72 h. RESULTS: We systematically investigated the cardiac developing toxicity of AgNPs on the embryos of zebrafish. The results demonstrated that 2 or 4 mg/L AgNPs exposure induces cardiac developmental malformations, such as the appearance of pericardial edema phenotype. In addition, after 72 h of exposure, the mRNA levels of cardiac development-related genes, such as myh7, myh6, tpm1, nppa, tbx5, tbx20, myl7 and cmlc1, were significantly lower in AgNPs-treated zebrafish embryos than in control zebrafish embryos. Moreover, RNA sequencing, KEGG (Kyoto Encyclopedia of Genes) and Genomes and GSEA (gene set enrichment analysis) of the DEGs (differentially expressed genes) between the AgNPs-exposed and control groups indicated that the downregulated DEGs were mainly enriched in focal adhesion pathways. Further investigations demonstrated that the mRNA levels of focal adhesion pathway-related genes, such as igf1ra, shc3, grb2b, ptk2aa, akt1, itga4, parvaa, akt3b and vcla, were significantly decreased after AgNPs treatment in zebrafish. CONCLUSION: Thus, our findings illustrated that AgNPs could impair cardiac development by regulating the focal adhesion pathway in zebrafish.