Molecular characteristics and expression pattern analysis under pathogen stress of SOCSs genes in three species of yellow catfish

Suppressor of cytokine signaling (SOCS) is a class of intracellular proteins that inhibited cytokine signaling in JAK/STAT pathway. To explore the function of SOCS in fish immune response, hybrid yellow catfish “Huangyou-1” and its female parent Pelteobagrus fulvidraco and male parent P. vachell were selected as the research object in this study. The immune related genes SOCS1, SOCS2 and SOCS3 of hybrid yellow catfish “Huangyou-1” were cloned and preliminarily analyzed by bioinformatics. The Quantitative Real-time PCR (qRT-PCR) technology was used to detect the expression patterns of these three genes after infection of Aeromonas hydrophila and Edwardsiella ictaluri into hybrid yellow catfish “Huangyou-1” and its parents. The results show that the ORF length of SOCS1, SOCS2 and SOCS3 genes of hybrid yellow catfish “Huangyou-1” was 561, 735 and 672 bp, encoding 186, 244 and 223 amino acids respectively, and prediction results revealed that SOCS1, SOCS2 and SOCS3 proteins contained SH2 conserved domains and SOCS box. The expression pattern of SOCS1, SOCS2 and SOCS3 genes showed tissue specificity in hybrid yellow catfish “Huangyou-1”, P. fulvidraco and P. vachell. After being challenged with A. hydrophila or E. ictaluri, the transcripts of SOCS1, SOCS2 and SOCS3 were all significantly increased, reached the peak at 24 h and then gradually returned to normal levels in liver, gill and head kidney in hybrid yellow catfish “Huangyou-1” and its parents (P<0.05). In addition, compared with parent P. fulvidraco and P. vachell, hybrid yellow catfish “Huangyou-1” had higher mRNA levels in SOCS1, SOCS2 and SOCS3 after the infection of E. ictalurid, showing a stronger immune regulation ability and having pathogen specificity. Our study provides a basis for the analysis of the immune defense regulation mechanism of the SOCS family of Pelteobagrus.