Expression Characterization And Functional Analysis Of Heme Oxygenase-1in Zebrafish

Heme oxygenase-1(HO-1) is an initial and limiting enzyme in heme degradation. It can protect cell and tissues through the potential of antioxidation, anti-inflammation anti-apoptosis and improve microcirculation. When its expression is abnormal, many diseases will appear. Previous studies have found that HO-1gene was a hypoxia-responsive gene. In this study, we make a preliminary assessment of the function and expression pattern of HO-1in zebrafish.The whole length of HO-1cDNA consists of1279bp and open reading frame (ORF) of819bp encode a polytide of273amine acid. Compared with other species, the protein sequence of HO-1was conserved in vertebrates. RT-PCR detection showed that HO-1transcript existed in unfertilized eggs. Its level increased from24hpf and remain a high level expression until72hpf. The tissue expression pattern analysis of HO-1by WISH and RT-PCR showed that HO-1was expressed ubiquitously and the expression in brain, heart, gill and liver was obviously higher than others.Then we investigate the function of HO-1in the early development of zebrafish using overexpression and knock down technology. The results showed that over-expression of HO-1had no apparent effect on the early development of zebrafish. Knocked down of HO-1gene by HO-1MO made the embryo development retarded. The abnormality and lethal rates of embryos after MO treatment were significantly increased compared with control. However, co-microinjection HO-1mRNA and morpholino can restore the phenotype which proved to be caused by low HO-1mRNA level.Moreover, we detect the function of HO-1in zebrafish adaptation to hypoxia. We found that the development of zebrafish embryos retarded and abnormalities rates of embryos increased under hypoxia conditions. Real-time PCR analysis showed that the expression of HO-1mRNA also increased after hypoxia treatment. Knock-down of HO-1mRNA expression under hypoxia conditions can restore the phenotype of embryos caused by hypoxia. These results showed that HO-1plays an important role in zebrafish embryo genesis and hypoxia adaptation.