Effect of cadmium on the gene transcription regulation function of nuclear transcription factor ShDorsal in the freshwater crab Sinopotamon henanense.

Dorsal is the nuclear transcription factor in the Toll signaling pathway of invertebrates, which can mediate the production of antimicrobial peptides (AMPs) in response to pathogen invasion and plays an important role in the innate immunity of invertebrates. This study identified and cloned the dorsal homologous gene, Shdorsal, from the freshwater crab Sinopotamon henanense. The total length of the Shdorsal (S. henanense Dorsal) was 2483 bp, of which the open reading frame was 1644 bp, encoding 547 amino acids. Structural prediction of Dorsal proteins revealed that ShDorsal contains conserved RHD and IPT domains and belongs to the classII NF-κB transcription factor. ShDorsal shared high homology with other crustaceans and clustered with Scylla paramamosain Dorsal (SpDorsal) and Portunus trituberculatus Dorsal (PtDorsal) as one clade. Firstly, we explored the expression pattern of Shdorsal and found that Shdorsal has the highest expression in hemocytes. The expression of Shdorsal in gill tissue was significantly reduced 12 h after the challenge with Aeromonas hydrophila. In contrast, the expression of Shdorsal in hemocytes initially increased and then decreased over time. We also found that Cadmium (Cd) has an inhibitory effect on the response of Shdorsal to the challenge of A. hydrophila. In addition, Immunofluorescence localization of ShDorsal revealed that ShDorsal was mainly localized in the cytoplasm. At the same time, as Cd concentration increased, it adversely affected the transfer of ShDorsal from the cytoplasm to the nucleus. Finally, RNA interference technology was used to verify that ShDorsal has a regulatory effect on downstream-related antimicrobial peptides. In summary, our findings investigated the antimicrobial characteristics and mechanism of ShDorsal in response to Cd, supplemented the Toll signaling pathway regulation mechanism in response to Cd stress, and provided the scientific basis for an in-depth understanding of the natural immune mechanism of crustaceans.