Molecular characterization, expression and response to immune challenges of 3 members of the toll-like receptor superfamily 11 in the golden pompano (Trachinotus ovatus)

Abstract

Toll-like receptors (TLRs) are one of most important innate immune receptors, and play critical roles in pathogen recognition and activation of both innate and adaptive immune responses. In this study, we identified 2 tlr13 and 1 tlr23 genes in golden pompano (Trachinotus ovatus) by whole-genome screening, and their transcription patterns in response to various immune challenges were investigated. The open reading frames (ORFs) of, Totlr13–1, Totlr13–2 and Totlr23 are 2868, 2844 and 2802 bp in length, encoding 955, 947 and 933 amino acids, respectively. Multiple sequences alignment and protein structure analysis showed that these TLR receptors share high sequence homology. Phylogenetic analysis showed that Tlr13 comprises 2 subclades including Tlr13–1 and Tlr13–2, implying two Tlr13 paralogs may be widely existed in teleost. These three tlrs are extensively distributed and show a consistent pattern, with high expression levels in brain, kidney and spleen. In brain, intraperitoneal (IP) injection of both LPS and poly I:C induced Totlr23 expression at 24 h, while promoted Totlr13–1 and Totlr13–2 expressions at 12 h. In kidney and spleen, Totlr23 expression was dramatically increased at 3 h after LPS and poly I:C administration whereas Totlr13–1 and Totlr13–2 expressions slightly increased at 6 h and 24 h after LPS stimulation. Results revealed that both Tlr13s and Tlr23 may be involved in immune response in various tissues. These findings will expand our understanding about the evolutionary history and functional characteristics of the TLR11 superfamily in vertebrate.