Regulatory function of β1,4-galactosyltransferase I expression on Lewis-Y glycan and embryo implantation

• β1,4-GalT-I expression in uterine endometrium and embryo implantation is unclear.
• β1,4-GalT-I might regulate adhesion of uterus–embryo and embryo implantation.
• β1,4-GalT-I might regulate adhesion by regulating LeY glycan expression.

β1,4-Galactosyltransferase I (β1,4-GalT-I), a key enzyme in glycobiology, mediates several biological mechanisms. However, the correlation between β-1,4-GalT-I expression in the uterine endometrium and embryo implantation remains unclear. This study aims to elucidate the relationship between β1,4-GalT-I and LewisY (LeY) glycan during embryo implantation. So far, using green fluorescent protein as an indicator, β1,4-GalT-I interference plasmid (pcDNA3.0-siGalT I), overexpression plasmid (pcDNA3.0-HA-GalT I), interference control plasmid (control pcDNA3.0-siGalT I), and empty vector (pcDNA3.0) were transfected into human uterine epithelial RL95-2 cells that imitate the receptive endometrium. Invasive embryos at pre-implantation and treated RL95-2 cells were co-cultured to determine embryo attachment in each of the transfection groups. The results showed that plasmid transfection was successful in all the groups. β1,4-GalT-I and Fucosyltransferase 1 (FUT1) gene expression declined in the interference group, and the synthesis of LeY decreased accordingly, but the expression of this antigen increased in the overexpression group. After co-culturing of the embryos and 36 h transfection of RL95-2, the results of these in vitro implantation models showed that the attachment rate was lower in the interference group (30.0 ± 0.2%) than in the untreated group (50.0 ± 0.6%), empty vector group (50.0 ± 0.2%), and interference control group (46.7 ± 0.6%), however, it was highest in the overexpression group (70.0 ± 0.2%). These results indicated that β1,4-galactosyltransferase I possibly regulate mutual uterus–embryo adhesion and embryo implantation by regulating cell surface LeY glycan expression.