Response of intestinal signaling communication between nucleus and peroxisome to nanopolystyrene at predicted environmental concentration
The molecular responses of organisms to environmental toxicants at environmentally relevant concentrations are still largely unknown. Nematode Caenorhabditis elegans is a sensitive animal model to assess the environmental exposure. We here determined the role of canonical Wnt/β-catenin signaling, a conserved molecular signaling among different organisms, in regulating the response of nematodes to nanopolystyrene (100 nm) at predicted environmental concentration (1 μg/L) and the underlying mechanism. Among the components of canonical Wnt/β-catenin signaling pathway, nanopolystyrene (1 μg/L) only decreased GSK-3 expression and increased β-catenin BAR-1 expression. GSK-3 acted upstream of BAR-1 to regulate the response to nanopolystyrene, and the intestine-specific activity of GSK-3-BAR-1 signaling cascade in regulating the response to nanopolystyrene was observed. Transcriptional factor DAF-16 and peroxisomal protein PRX-5 were identified as downstream targets of both BAR-1 and Wnt effector POP-1 in regulating the response to nanopolystyrene. During the control of response to nanopolystyrene, DAF-16 and PRX-5 functioned synergistically, suggesting that the intestinal canonical Wnt/β-catenin signaling mediates two different molecular signals to regulate the response to nanopolystyrene. In the peroxisome, KAT-1 and ACOX-1.6 were further identified as downstream targets of PRX-5 to regulate the response to nanopolystyrene. Therefore, exposure to nanopolystyrene could activate the canonical Wnt/β-catenin-mediated signaling communication between nucleus and peroxisome. Our results suggest the crucial function of canonical intestinal canonical Wnt/β-catenin-mediated nucleus-peroxisome signaling communication in response to the nanopolystyrene exposure at predicted environmental concentration.