Galectin-related protein from Oreochromis niloticus: Molecular, and transcriptional features and biological responses against microbial pathogens

Abstract

Galectin is a kind of lectin that can promote the cell adhesion, proliferation, and phagocytosis and participates in immune regulation and destruction of microbes. In this study, a galectin-related protein (On-GRP) homolog was identified from Nile tilapia, and its expression level and antibacterial ability were studied. The Open Reading Frame, which encoded a 179 amino acid protein (GenBank accession no: XM_005733705.1), was 537 bp. The On-GRP possessed a carbohydrate recognition domain. qRT-PCR showed that the On-GRP was detected in the examined tissues in healthy Nile tilapia, and the highest expression levels was observed in the skin. After challenge with Streptococcus agalactiae, the On-GRP expression was up-regulated significantly (P < 0.05) in the whole blood, head kidney, gills and thymus. In addition, the recombinant On-GRP (rOn-GRP) could agglutinate and bind Streptococcus agalactiae and Aeromonas hydrophila. In vitro and in vivo bacteriostatic tests showed that the rOn-GRP could inhibit the growth of bacteria. Besides, the rOn-GRP could promote the phagocytic ability of macrophages to engulf bacteria. Over all, this study indicated On-GRP is involved in the immune responses of Nile tilapia against bacterial pathogens.