miR-21 is involved in skeletal deficiencies of zebrafish embryos exposed to polychlorinated biphenyls.

Polychlorinated biphenyl (PCB) exposure increases the incidence and severity of skeletal diseases, but little is known about the mechanisms that mediate this relationship. We exposed zebrafish embryos to PCB1254 and assessed the changes in bone morphology protein receptor II (BMPRII), which is involved in bone formation and embryonic development, miRNA-21, for which BMPRII is a known target, and calcium metabolism. PCB1254 upregulated the expression of miR-21 and suppressed BMPRII expression. The inhibition of miR-21 reversed the downregulation of BMPRII and alleviated the PCB1254-induced loss of calcium. These findings suggest new biomarkers of developmental defects of the skeleton caused by PCBs.