Heterologous expression of newly identified galectin-8 from sea urchin embryos produces recombinant protein with lactose binding specificity and anti-adhesive activity

Galectinfamily members specifically bind beta-galactosidederivatives and are involved in different cellular events, including cell communication, signalling, apoptosis, and immune responses. Here, we report a tandem-repeattype galectinfrom the Paracentrotus lividussea urchin embryo, referred to as Pl-GAL-8. The 933nt sequence encodes a protein of 34.73 kDa, containing the conserved HFNPRF and WGxExR motifs in the two highly similar carbohydrate-recognition domains (CRD). The three-dimensional protein structure model of the N-CRD confirms the high evolutionary conservation of carbohydrate binding sites. The temporal gene expression is regulated during development and transcripts localize at the tip of the archenteronat gastrula stage, in a subset of the secondary mesenchyme cells that differentiate into blastocoelar (immune) cells. Functional studies using a recombinant Pl-GAL-8 expressed in bacteria demonstrate its hemo-agglutinating activity on human red blood cells through the binding to lactose, as well as its ability in inhibiting the adhesion of human Hep-G2cells to the substrate. The recent implications in autoimmune diseases and inflammatory disordersmake Gal-8 an attractive candidate for therapeutic purposes. Our results offer a solid basis for addressing the use of the new Pl-GAL-8 in functional and applicative studies, respectively in the developmental and biomedical fields.