Genome-wide characterization of Toll-like receptors in black rockfish Sebastes schlegelii: Evolution and response mechanisms following Edwardsiella tarda infection

As one of the key components of pattern recognition receptors, Toll-like receptors (TLRs) play pivotal roles in the innate immune system. However, little information is available about the TLR genes in Sebastes schlegelii. In the present study, 17 TLR genes were identified and classified based on the whole genome database. Tandem duplication events in TLR1, TLR2, TLR5 and TLR13 played major role in the expansion of S. schlegelii TLR genes; both TLR2-3 and TLR2-4 had the same largest number of introns/exons, 11 exons and 10 introns. The syntenic analysis showed neighboring genes of TLR genes were most conserved in S. schlegelii and in L. crocea. Phylogenetic and evolutionary analysis showed that these TLR genes were divided into five subfamilies and exhibited different selection pressures. Meanwhile, the expression patterns of TLR genes in the intestine after E. tarda infection were investigated by qRT-PCR. Finally, protein and protein interaction (PPI) network analysis indicated that TLR genes interacted with IFN-inducible genes, inflammatory cytokines, and participated in MyD88-dependent pathway. In summary, this study provided valuable information for further functional characterization of TLR genes in S. schlegelii.