Cloning, expression and function of Galectin-6 from Paralichthys olivaceus

Abstract:

Galectin-6 is a member of the β-galactoside-binding lectin family, which has been widely studied in mammals (e.g., Lgals6). Galectin-6 has been cloned from several teleost fishes, such as Maylandia zebra, Esox lucius, and Poecilia formosa, but there are few studies on its function. In this study, we analyzed the molecular characteristics of Galectin-6 extracted from Paralichthys olivaceus (PoGalectin-6) and studied its immune-related functions. The full length of the open reading frame (ORF) of PoGalectin-6 cDNA is 1089 bp, encoding 362 amino acids containing two carbohydrate recognition domains (CRDs). Multiple sequence alignment and phylogenetic tree analysis showed that PoGalectin-6 is highly similar to Scophthalmus maximus Galectin-4 (approximately 80.9%). Tissue distribution experiments demonstrated that PoGalectin-6 is specifically expressed in intestinal tissues. The expression level of PoGalectin-6 in the intestine significantly increased after Edwardsiella tarda stimulation, and the highest expression level was observed at 12 h after infection. Recombinant PoGalectin-6 (rPoGalectin-6) exhibited binding ability to gram-positive (Bacillus subtilis, and B. cereus) and gram-negative (Aeromonas salmonicida, E. tarda, and Vibrio vulnificus) bacteria. rPoGalectin-6 showed Ca2+-dependent agglutination activity against B. pumilus, B. subtilis, A. salmonicida, and E. tarda. This study suggests that PoGalectin-6 may play an important role in the immune response against E. tarda infection, laying the foundation for exploring the immune functions of Galectin-6 in teleosts.