Copper elevated embryonic hemoglobin through reactive oxygen species during zebrafish erythrogenesis

• The unbalance of copper in the body, excess or deficiency, will lead to pathological conditions in humans.
• In this study, we found that copper generated ROS mediated its induced hemoglobin expression, which partly revealing the underlying molecular mechanisms of copper therapy for anemia.
• Moreover, we revealed that copper homeostasis was broken by its induced ROS and ROS helped with copper overloading in the body, which could be applied as a novel therapy target for copper-caused diseases.

Copper, as an essential trace mineral, can cause diseases such as childhood leukemia at excess levels, but has been applied in anemia therapy for a long time. However, few reports have studied its role during hematopoiesis at the molecular level in an animal model. In this study, by microarray, qRT-PCR, whole-mount in situ hybridization and O-dianisidine staining detections, we revealed the increased expression of hemoglobin in copper-exposed embryos. Secondly, we found that copper-exposed embryos exhibited high levels of reactive oxygen species (ROS), and genes in oxygen binding and oxygen transporting were up-regulated in the embryos. Finally, we found that ROS scavengers NAC, GSH, and DMTU not only inhibited in vivo ROS levels induced by copper, but also significantly decreased high expression of hemoglobin back to almost normal levels in copper exposed embryos, and also helped with copper elimination from the embryos. Our data first demonstrated that ROS mediated copper induced hemoglobin expression in vertebrates, partly revealing the underlying molecular mechanism of copper therapy for anemia. Moreover, we revealed that copper homeostasis was broken by its induced ROS and ROS helped with copper overloading in the body, which could be applied as a novel therapy target for copper-caused diseases.