The potential role of galectin-4 in protecting the intestinal barrier in the lined seahorse Hippocampus erectus

Abstract

Galectin-4 is a prominent antimicrobial peptide primarily expressed in the gastrointestinal tract of animals. It plays crucial roles in antimicrobial defense and in regulating the repair of intestinal epithelial cells. Given the unique immune system in seahorses, which are known for male pregnancy, the function of galectin-4 in their intestinal tract, which lack gut-associated lymphoid tissues, remains unknown. In this study, we identified a galectin-4 gene (HeGal-4) in the lined seahorse (Hippocampus erectus). The sequence length of the open reading frame (ORF) was 1041 bp, encoding 346 amino acids. The mRNA expression of HeGal-4 in the intestine was significantly higher than that in other internal organs. However, the synthesized peptide fragment (HeGal-4(302–315)) from the functional domain of HeGal-4 only showed moderate inhibitory effects against Escherichia coli, Klebsiella pneumoniae, and Micrococcus luteus. Interestingly, in situ hybridization showed that HeGal-4 was predominantly expressed in seahorse intestinal epithelial cells, while genes associated with galectin-4 in the repair of intestinal epithelium, such as β-catenins, were highly expressed in their intestines. Therefore, our results suggest that HeGal-4 may be crucial for regulating the repair of intestinal epithelial cells in seahorse intestinal epithelial cells, and that it possesses significant potential for the prevention and control of intestinal diseases in seahorse aquaculture.