Inhibited expression of seven hemocyanins in hepatopancreatic necrosis syndrome (HPNS) crabs regulated by Kruppel and E75

Abstract Hepatopancreatic necrosis syndrome (HPNS) severely threatens the development of Eriocheir sinensis farming. To date, no consensus has been reached about the etiology and pathogenesis of HPNS. In this study, we investigated the effects of HPNS on the copper-containing respiratory protein (hemocyanin), the ecdysone inducible transcription factor (E75), and the zinc finger-containing transcription factor (Kruppel). We also determined the relationship between hemocyanin and the two transcription factors. Seven hemocyanin variants, four E75 isoforms, and a Kruppel-like factor were characterized in E. sinensis. The 3′ and 5′ ends of hemocyanin possessed molecular diversity, which was apparently associated with its multifunctionality. Four E75 isoforms were generated by the alternative splicing of the 5′ exons, and they originated from a single copy gene. Hemocyanins, EsE75, and EsKruppel were mainly expressed in the hepatopancreas, which is the most primary organ for the clinical characterization of HPNS. The expression of the hemocyanins and two transcriptional factors (EsE75 and EsKruppel) were significantly decreased and increased in the crabs with HPNS, respectively. Moreover, silencing of EsE75 and EsKruppel resulted in an evident increase in the synthesis of hemocyanins, indicating that EsE75 and EsKruppel acted as the transcription repressor of the hemocyanin gene. However, the detailed mechanisms by which E75 and Kruppel regulated the transcription of hemocyanin in E. sinensis need to be more thoroughly studied in the future. This study provides new information on hemocyanin, E75, and Kruppel that were influenced by HPNS in E. sinensis. The results will help to enhance the understanding of the causes and pathogenesis of HPNS.