Characterization of a nucleotide-oligomerization domain (NOD) like receptor C5 (NLRC5) subfamily member from black rockfish ( Sebastes schlegelii ), portraying its transcriptional responses against immune stimulants

Nucleotide-oligomerization domain like receptors (NLRs) are recently identified group of pattern recognition receptors which involve in sensing broad range of pathogen associated molecular patterns or damage associated molecular patterns to trigger corresponding immune responses in host cells. In this study, we identified and characterized a NLRC5 family member from a previously established black rockfish cDNA database, designating as ‘RfNLRC5’. The complete open reading frame of RfNLRC5 consists of 5808 bp which encodes for a protein of 1936 amino acids with the predicted molecular mass of 213 kDa. Intriguingly, RfNLRC5 harbored only two typical domain signatures of NLR superfamily, namely NACHT domain and LRRs. However, it was phylogenetically closely related to the telostan counterparts. As expected, RfNLRC5 shared significant sequence compatibility with its teleostan counterparts, eminently with that of large yellow croaker. As detected by our qPCR assay, RfNLRC5 was universally distributed in tissues examined, albeit with different levels. Therein, more pronounced expression levels were detected in blood cells and spleen tissues. After treating the naive fish with immune stimulants; lipopolysaccharides and Polyinosinic:polycytidylic acid (poly I:C), RfNLRC5 mRNA expression in blood cells and spleen tissues was found to modulate significantly with notable inductive responses. Collectively, our results in this study hint a potential role of RfNLRC5 in host innate immune responses against bacterial or viral infections.